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Apr - American Radio History

1. K2615 Motherboard for ZX81 25 69 K2616 Motherboard for Spectrum 25 69 K2609 DC Output board 19 01 K2610 A D Converter 28 26 K2611 Opto coupler input board 20 66 K2614 Centronics interface 30 83 K2618 NEW KITS NOW AVAILABLE D A converter 24 66 K2594 Zero Cross Programmable timer 11 41 K2598 Car Amplifier 15 41 K2600 2Ampdimmer 5 32 K2601 Stroboscope 10 79 K2602 4channelrunning light with music modulator 20 55 K2606 LED audio power meter 12 48 SENDFOR FREE ILLUSTRATED POSTER OF COMPLETE RANGE ANDLIST OF STOCKISTS from address below CIRCLE 064 FOR FURTHER DETAILS VELLEMAN UK LTD WIRELESS WORLD MAY 1984 P O Box 30 St Leonards on Sea East Sussex TN35 7NH Tel 0424 753246 WWW americanracdiohistorv com A2326 AH205 AH21 A AH221 AH238 AH2511 AH2532 AJ2256 B0512A BK56 BK448 BK482 BK4B4 BK486 BK48BA BK7703 BLTII9 BTS BT5B B117 BT 7A BT19 BY69 Br95 BT125 Bri27 CIK E39 C3JA CIIL C16J CK 1907 CK5687WA o1si6 baa 0A2010 0R2100 OR2110 ovs E55L EB0CC EGOF EBOL E8 CC EBBCC E89F E90CC 92cC E1300 180F 1e8cc E5070 t89 EBC91 ES8F89 EC90 FCC32 ECC3O0 ECC O ECCB ECCB2 ECC83 ECCB5 ECC88 ECCS ECC189 ECF80 ECF86 ECFBO ECH81 ECL82 CL83 ECLB6 EF40 EFBO EF85 EFB5 EF89 EF9 EF92 EF93 EF94 EF95 EF183 EF 84 EFL200 M01901 ML7815 MLB536 ML8741 Mu7
2. SERVICES DESIGN AND DEVELOPMENT ANAL SMALL BATCH PCBs produced from your art OGUE DIGITAL RF AND MICROWAVE work also DIALS PANELS LABELS Camera CIRCUIT AND SYSTEM DESIGN Also PCB work undertaken FAST TURNAROUND De design mechanical design and prototype sinall tails Winston Promotions 9 Hatton Place London ANALOG COMPUTERS LIMITED CAPACITY NOW AVAILABLE FOR chartpak stockist batch production Adenmore Limited 27 ECIN 8RU Tel 01 405 4127 0960 9797 Longshot Estate Bracknell Berks Tel f Bracknell 0344 52023 656 DESIGN AND CONSULTANCY of micropro Design amp Development Complete Artwork Service Camera cessor digital and analogue equipment Complete E P C B s amp PANEL LABELS to vour require service from feasibility and design to prototype Work Prototype thru to Production PCB Manufacture Assy ments Design Prototypes Production and commissioning Advice on test and design of G N SLEE CUSTOM PRODUCTS 78 Derry Grove Thurnscoe Rotherham Yorks 63 OTP Electronics 24 Timbermans View Basildon Telephone 0709 895265 2401 Essex Tel 0268 558831 2295 Wa C a VERBGATE LTD WANTED dedicated test equipment or ATE DPM 5 Cork Street Eccles Maidstone Kent ME20 7HG TELEPHONE 10622 79987 TELEX 965633 CIRCOLEC THE COMPLETE ELECTRONIC SERVICE Artwork Circuit Design PCB Assembly Test amp Repair Service Q A Consultancy Prototypes Final Assembly Full
3. Fig 45 Trace shows the group delay response of the modulator and demodulator 50ns cm Fig 41 Part of the TX10 receiver showing components associated with the decoder chip Y BK GY G CY W to tube base board Green O crt cathodes Up to SV pk pk available as video drive GL4850 1 if in use x Field blanking pulse t V typical blanking level of 2V ond maximum 1k 33uH and Sip wh te level cf 9V added to improve tuLe drive frequency WWW americanradiohistorv com we or TELEVISION Fig 46 A BBC 1 transmitter in the south of England Figures show the amplitude response right group delay characteristic Fig 47 middle and i t s test signal performance Fig 51 below To reduce the need for iow impedance drive stages and to avoid awkward inductor or capacitor values itis often advantageous to scale the network impedance To use standard 75ohm test equipment these networks are suggested impedance matching for measurement R1 gt R R is 510 the characteristic impedance of gaussian band pass filter used for chroma filtering Fig 34 March R is 752 Calculated values R 471 012 R 81 21 Power loss 14 01dB Forward voltage loss 22 33dB Reverse voltage loss 5 68dB Insertion loss 10 51dB Filter To 7SN spectrum or analyser or group delay line delay measuring set A Tocro 106 07 15011 150 or 106 07 7511 Gen R is 1509
4. AD161 BDI BY 187 TDA 5600 700 BRIDGE 25620281 200 AD162 80179 BY196 0 TDA25930 800 N 4004 0 040 A RECTIFIERS API24 BD 181 BY206 ie ERI EA S TASOV 0160 P ZENER ARI25 D 80201 8Y20 10426900 700 25629520270 ZENER 14 100v 0 180 B2 Y8B Range AFI26 80202 8Y223 TiP29 0150 IN 4007 8060 14200V 0 190 APIS D 8203 amp vxio TiP29A 0220 IN 3148 0 020 2SD2330 30 14 400V0 210 AF139 BD204 np2gc 9259 IN 5400 0 090 4000 gt 36 ra amp 00v0 230 AF238 80222 CA270 MP3 oi IN 5401 0100 MB3712 1500 13W Zener 1A 800V0 280 ALT 80225 Ca3ogs 0250 mpana oze M5402 0100 UPC 1800 82x61 Barge 2Ar100v 350 ALIS D232 CA3089 1500 11p32 gag IN S403 0110 1 awanane 2a 200v0 360 ASZIS 8D237 CA3240 0 900 ib32A n240 IN S404 0110 2A 40000 420 ASQ 80238 C1060 0230 rp33 osoo IN 3405 0120 2A 600V0 540 R5626 Mask programmable to your specification 0 Pipes Mergeroroo Hoata 2508 mias ani S MEMORIES E posed D x Aun HD437 D 27 0 Ti S ADR SOCKET Reticon also provides a wide variety of other stan n FE wieso vem nest oeeo OM S408 0990 gos aii 2000 Meigovo 680 NT a 5 AY 106 80536 MJ2501 1100 rnipa24 0220 Mpn ho 3A 600V0 780 dard and specialised custom filters and signal ae ansar gamo Muzussessa muc oas gt iar a EU 1 1 1 z BAM BDX32 MJ300 4150 rip o REGULATORS 20 2764 254 1004 l processing devices using Reticon s proven NMOS BAISS BDx65 wuezaaaan mpag aoo 7803 0380 or ae 1600 Switched C itor
5. 195 13 20 5672 4 50 DC90 120 EN92 450 14500 TTM 1 50 ZM1005 800 ST4 5 95 1307 3 20 i DCX4 1000 ECCES Philips Esus 2 25 00 M8137 550 orao o0 Tris 3495 ZM1020 8 95 U4G_ Y95 SGHGA 0 80 pn 235 Se aio 1200 ECCBA 0 50 EYS1 0 80 M8162 5 60 QP25 1 00 TY2 125A 60 00 2M1021 8 00 5U4GB 2 50 Bake y so 13E 115 00 5692 3 50 DCX4 5000 Eccas oso EYS 152 Maiss 5so QQE03 126 50 T4400 7000 fMi 788 svaG 125 caus 200 1457 a 90 5696 350 25 00 j EO3 20 0951 i 17EW8 0 95 5704 3 50 DET 6 2850 cess 278 Eves 5 95 M m 27 00 365 00 ZM1050 1400 SZ4GT 085 6GW6 250 jog 275 Eig 6 50 DETI8 2850 EC 91 2 00 EY86 87 0 50 M8196 5 50 QQE06 40 TY8 600W 2M1082 9 00 6 30L2 0 70 E 135 1803 1 60 5725 2 50 DET24 3900 Eccigo 072 EY88 955 mara 50 39 50 36509 SMr soo GatQ ioo Guest v20 1963 1700 3725 250 DET25 2200 ECCia9 078 EY9 5 550 Mg223 aso QQVO2 636 50 TYS2 250 p ENAIT 2300 GABGI i1180 one 110 1944 2335 5727 2 50 Brat an Reim RED 053 mea 19 BOvoagS e umop Cim BS ue GAS imt gis Ime RG mg ie 91 0 7 S J0 QQV03 20 35 d 1906 9 00 5750 00 Ux ip non age UR 1m Mus sm ge ue US UR qm Me iB ne Ine wms Sei i DF96 0 65 d EZ ji 2QvO3 208 E d B 20D1 0 70 5763 4 95 Dfa meoj CRX eo Egat i veu maso oo uas ggo NOST 13 acs gso S 55 Zopa my MA 1m DH63 120 ecfao oss EZ80 060 Mhs 35o Q
6. 350 PEN45 3 00 RS685 5495 XFWa47 1 50 4C27 25 00 6CaG i150 11E3 55 00 425A5 800 A2599 3750 EB4i 3 95 EL33 400 i35 2000 PEN45DD 3 00 RS688 5215 XPWO 1 50 aC28 25 00 6C 250 2AG8 150 a3lU 2 00 A2900 1150 EB9 0 60 EL34 226 Krag 4 00 PEN46 2 00 S6F17 5 95 XG2 6400 4CX2508BITT 22d 250 12AL5 1 00 572B 35 00 A3042 24 00 EBC33 250 Et34Philips KTS 400 PFL200 125 S6F33 28 95 3500 3550 Pi Scia 250 12AT6 0 65 705A 8 00 A3283 2400 EBCA 195 30 Kte 4 00 PL21 2 50 S11E32 38 00 XG5 500 22 50 4CX2508 CAL T0 12AT7 1 15 708A 8 00 AC HL DD 4 00 EBC81 150 E136 150 amp r 3 200 PL36 0 95 S30 2K 1200 XL SV 150 EIMAC 58 00 ECAT 450 12AT7WA 2 50 715A 6 00 AC THI 4 00 EBC90 0390 EL37 9 00 C166 OSRAM PL38 150 104 1K 10 00 XL628FT 7 50 a4CX2508 ECBS 195 12AU6 1 50 715C 4500 ACT22 59 75 EBcai 0 90 EL38 6 00 1050 PL8 0 72 S109 1K 15 00 XNP 2 2 50 surplus ex 6CDSGA 4 50 12AU7 0 55 725A 275 00 AC VP2 4 00 EBF33 250 EL4 350 kresusa 715 PL8IA 0272 S130 5 95 XP1002 29 00 government ere iso 2AV6 0 80 803 14 95 AC S2PEN 8 50 Egr8 amp 0 66 EL42 2 00 KT66 GEC PL82 060 130P 5 95 XR1 1600A 1250 oie 10 35 12AX4GT 1 00 805 39 00 AH221 39 00 Egra3 065 EL81 6 95 taas Plas 052 C1 800 5 00 4950 4CX2508 eens 988 12AX7 065 807 1 60 AH238 39 00 EBF85 0 95 EL82 0 58 KT77 Gold Lion PL84 0 78 SC1 1200 5 00 XR1 3200A tested ex 6CL8BA 200 2AX7WA 2
7. ADVANCE YOUR CAREER IN FUTURE PRODUCT DEVELOPMENT Project Managers C 18K Technical Managers C 16K HIGH TECHNOLOGY EQUIPMENT Several unique opportunities affording excellent career prospects with a large expanding performance orientated company exist for engineers with a degree or HNC in Physics or Engineering preferably Electronics or Systems Engineering but possibly Mechanical Engineering Candidates shoud have acquired good systems experience whilst working in the Electronics or Defence Industries as a team leader or group leader and ideally will have acquired practical knowledge of prototype production or trials Your task will be to assist our client who has developed an enviably secure base in the development and manufacture of complex weapons systems to develop new business areas for high technology systems in both the defence and commercial sectors The number of persons ultimately involved in a project will vary from 20 to 750 and the development costs will range from 20M to 200M and consequently there will be tremendous opportunities for you to progress to the control of the running of very large projects as well as to higher levels of management By proposing developing and evaluating systems and design options producing prototypes and arranging for all necessary trials and tests your team s objective will be to produce complete technical and cost proposals for complex state of the art systems
8. MIDWICH CHED COMPUTER COMPANY LIMITED RICKINGHALL HOUSE HINDERCLAY ROAD RICKINGHALL SUFFOLK IP22 1HH TEL DISS 0379 898781 BBC Microcomputers 8500 Family SN75454BP 024 Model B 34826 6502 D3 440 SN75468N 108 Model B Disc Int 43321 6502A D3 467 SN75491AN 046 NB Credit cards ate not accepted in payment for 6520 Dl 267 SN75492AN 061 BBC Microcomputers 6520A DI 280 TLOIOCP 038 6522 DS 347 TLOBICLP 028 BBC Micro Econet pH pS 120 T g 2 N Eulliange of procue s available Installation 6532A D2 587 TLOSRCP 0 z z Linear amp Interface 7 7 BBC Compatible Disc Drives A T o n 4 Devices TLI N Cased dnves hmshed to match the BBC Microwe 6402 600 TLOBICP 024 supplied complete with connecting cables manual amp y3 1015 D2 292 ILO82CP 041 and utilities disc AY3 1270 650 TLOB4CN 085 All single cased dnves may be expanded to dual AY3 8910 pe 448 TLOSICP 041 conhguration by the addition of the appropnate AY5 3600 D2 737 TLog2cP 060 uncased mechanism DP8304 DI 192 TLOS4CN 137 Disc capacity Single Dual Uncased L203 080 IEE 3 100K 40T 16083 29195 13000 LF398 317 TLA94CN 186 400K 40 80TD S 26495 47918 21500 LM301AN 024 LM308AN 073 TLA96CP 030 Trade quantity discounts are available LM308N 047 TLSO7CP 102 BBC3 Disc Interface 8495 Eva TIN aes UE ae Please send for our BBC Micro pnce list Full range of accessones avatlable LM324N 032 ZN4SIKIT 2585 LM339N 0 37 i LM348N 053 DIL Sockets rnories Me E Re
9. e 100n 715k Chroma unkill lt ehk Preset brightness 22 10 19Vde 05V 3 sync hp to wh 2 2 4Vdc burst 10n Ovde ok pk 0 38V pk pk chroma for 100 tars test signal ele Sandcastle puise WIRELESS WORLD MAY 1984 TELEVISION ness and the effect of channel fil ters Insertion gain and group delay responses are shown in Fig 44 and 45 The extra marker indi cates f the left end of the trace is zero in terms of the baseband fre quency 0 5 5MHz video Figs 46 and 47 are the gain and group delay responses with the trans mitter included in the chain Amplitude errors are within 1dB over the range 0 5 5MHz but the phase errors increase greatly above f Subtracting the test equipment errors back to back test Fig 45 from the Fig 47 full line trace gives the bro ken line response curve MUN indicates approximatel resulting group delay und mud that at 5MHz the erroris 100ns or nearly half the period of f With such an error it is difficult to obtain zero 7 8kHz twitter at the chroma transitions chroma input Delay line balance jm Delay line phase 43h Black tevel check Beum limiter WAKO ik 3g cig 24 25 26 418 119 3x 100n 2 22p 3 2 220 100p 3 GY B GY R rn 2 fsc fo From teletext or home computer PAL modifier sec Fig 34 Fig 44 Figure shows amplitude response of the test modulator and demodulator connec ed back to back 1dB cm
10. 100 kHz frequency range and switchable output impedances A high 30 Vpp amplitude in the asymmetrical mode with stepped and continuous attenuation a t0 Vpp floating output in the symmetrical mode and useful TTL or DIN loudspeaker outputs are pHiuips Test amp Measuring S Instruments further benefits In addition there is a choice of low distortion or fast settling modes PM 6309 is a simple to operate distortion meter that can handle all types of audio equipment It has been specially designed to provide appropriate signal generation plus an accurate distortion measuring capability within a single instrument It offers a built in RC oscillator total harmonic distortion THD 3rd harmonic distortion and rms measuring facilities It not only measures distortion according to DIN 45500 but also determines the distcrtion figure accurately when unstable audio signals are being applied Fully automatic operation means that all you do is connect the input select the test frequency and then read out the distortion Separate two channel testing is also possible for stereo equipment Use the inquiry service to obtain further information Inquiry No PM 5109 LF generator 061 PM 6309 distortion meter 062 Philips Test and Measuring Pye Unicam Ltd York Street Cambridge CB1 2PX Tel 0223 358866 Telex 817331 EX REQUIREMENT AMPLIFICATION SOLUTION CRIMSON More than ever Engineers Ent
11. 15 1 3um MHzkm GHzkm 6A2nm 2 100 2 100 GHzkm GHzkm 1dB km 1dB km types MONOMODE CHARACTERISTIC i Length bandwidth Step index product MHzkm 100 gt GHzkm Spacing between 900 repeaters km MHzkm 2 5dB km System cost 2100 GHzkm_ 28 y GHzkm Lifetime years 0 7dB km 100 Crosstalk GHzkm 25 Noise immunity GHzkm 3 Input output 2 SdB km isolation 100 gt GHzkm Weight size Cable connections i l ds respectively at 0 85um Fortunately a material disper sion minimum has been dis covered at 1 3um which allows for wide bandwidth transmission over distances 100GHz km even with an l e d Combined with the generally lower losses at 1 3um this has provided the impetus for much recent research at longer wavelength operations for future optical sources and detectors For any given fibre type and optical source there are therefore two main limitations on the maxi mum achievable bandwidth dis tance product that can be achieved Either modal delay spreading or material dispersion will dominate depending on the fibre type source type and operating wavelength Table 1 summarises the points discussed so far in a convenient form including figures for the highest modulating speeds so far achieved with I e ds and i l ds Clearly there is much develop ment to be done on source modu lation before the bandwidth pot ential of the best fibre system is reached Step index multimode fibres are
12. Finally anew transmitter was brought in but the station was off air for four days Satellites Although the European Ariane launch vehicle scored a major success with the Intelsat V communications satellite launched on March 5 the problems for Immarsat have not been entirely overcome The marine communications organization refused to accept the Intelsat V F7 spacecraft as unworkable and the March WIRELESS WORLD MAY 1984 COMMUNICATIONS COMMENTARY satellite is to an earlier design still not entirely debugged The F9 launch scheduled for summer 1984 has been put back to 1985 The problems with the booster engines on the Space Shuttle satellites has increased the demand for the Ariane and production of the European vehicle may have to be stepped up from six per year The sensitivity of the insurance market after the double failure with the Space Shuttle may bea deciding factor in the bright commercial future for the largely French Ariane despite the earlier set backs It remains to be seen however whether the market for high power DBS satellites will prove as large as forecast until recently DBS like multi channel cable systems are being subjected to a more realistic scrutiny Many of the would be cable programme providers in the UK have already merged or quietly vanished One of the fastest production jobs on a new scientific educational amateur radio satellite the second UOSAT design was successfull
13. If 21 6 8 we can choose f and R as preferred numbers Then log C is an integer and so Cis a preferred number We have defined the design limitations at the beginning not fudged them at the end For equations containing a square root log X will be n 2 and thus will bein the E12 range Mr Scott should ask himself what sort of people he thinks we are not to have noticed that 10 is not 1 5 And then what sort of a person do we think he is Thomas Roddam Arundel W Sussex WWW americanracdiohistorv com es i A DBX AND DOLBY Iam writing with regard to an article entitled BSR clambers out of depression in theJanuary 1984 issue of Wireless World which states that They dbx Inc have produced a neat little playback decoder battery operated for use with headphone cassette players for both dbx and Dolby B decoding If this statement is referring to the dbx PPA 1 decoder it is incorrect since this unit does not have a Dolby B type decoding facility In its dbx B mode the PPA 1 does have static decode characteristics that approximate to those of Dolby B type but it does not have the dual path circuitry the overshoot suppression the dual rate control circuit and other characteristics that it would need before it could be said to have Dolby B decoding I would appreciate it if you would advise your readers of this Ian Hardcastle Vice president Dolby La
14. LABORATORIES foniups Redhill Surrey RH1 SHA Tel Horley 5544 Together we can shape the future 2559 WIRELESS WORLD MAY 1984 WWW americanradiohistorv com Electronics Engineers 9561 Communications Design in High Tech Country REN Se At H M Government Communications Centre we re using the very latest ideas in electronics technology to design and develop sophisticated communications systems and installations for special Government needs at home and overseas With full technical support facilities on hand it s an environment where you can see your ideas progress from initial concepts through prototype construction tests and evaluation to the pre production phase with a chance to influence every stage Working conditions are pleasant the surroundings are attractive and the career prospects are excellent Ideally we re looking for men and women who have studied electronics to degree level or equivalent and have had some experience of design whether obtained at work or through hobby activities Appointments will be made as Higher Scientific Officer 7149 956D or Scientific Officer 5682 7765 according to qualifications and experience For further details please write to the address given below As our careful selection process takes some time it would be particularly helpful if you could detail your qualifications your personal fields of interest and practical experience and describe th
15. Oirect reading PNP NPN and diodes Hle leakage etc General purpose TCT 19 96 UK C P 655 PROBE KITS In wallets with adaptors etc BNC fittings for scopss counters generators atc xi 5 90 X1 X10 Switchable 10 00 X10 826 Demodulator 16 00 X100 16 00 UK C P free with other Item or 65p per 1 to 3 kits CATALOGUES CIRCLE 042 FOR FURTHER DETAILS WWW americanradiohistorv com Order by Post with CHEQUES ACCESS VISA or you can telephone your orders Up 10 1000 instant credit Available through Lombard Tricity Finance Send large SAE 20p UK Specification sheets Any model State which Send SAE Schools colleges companies Export free on written request 23 B BAMBER ELECTRONICS Marconi Modulation Meter Type 1F2301A 330 Pye Base Station Type F30 AM High Band amp Low Band rom 220 Servomex AC Voltage Slabiliser Type AC2 240 vac 9amp 45 Marconi RMS AC DC Voltmeter Type TF 2607 185 Pye Base Station Type F401 AM High Band 250 Servomex AC Voltage Stabitiser Type AC 240 vac 40amp 95 Marconi RF Power Meter Type 0A 7024 4 195 Pye Base Station Type F17 FM High Band 250 Hewleti Packard Sweep Generator Type 692D 1 8 4 2Ghz 300 Marconi UHF Attenuator Type TF 2168 100 Pye Reporter Type MF6 AM High Band amp Low Band 90 Tektronix Plug inPower Unit Type 133 with Type O Plugin 85 Wavetek LF Generator Type 380 Pye Europa Type M
16. The sequence of pulses for the dynamic memory is generated by a series of Schmitt buffers IC RAS is generated by the leading edge of memory request signal which triggers mono stable IC A potentiometer sets the pulse length For the devices specified in the diagram RAS should last for at least 200ns and should have a minimum off period of 120ns In practice this adjustment is not too critical with a system running at 4MHz as a complete RAS cycle lasts at least two clock cycles which corre sponds to 500ns Set the poten tiometer to give the off period required for the dynamic memo ries used or if measurement is not possible to its mid position for a 4MHz microprocessor or at or near its minimum for a 6MHz version Continued on page 51 WIRELESS WORLD MAY 1984 OPTICAL FIBRES Fibre optic communications First of a three part series reviews the fundamentals of fibre optic transmission and outlines the main advantages and limitations in using optical fibres as a communications medium Part 1 Optical fibres and waveguide transmission An optical fibre is a dielectric waveguide made of glass or occasionally of a transparent polymer and essentially consists of two regions a core region anda cladding region Fig 1 Protec tion and a degree of mechanical strength is provided by the outer jacket The fibre is characterized y a refractive index profile as a function of radial distance from the
17. Welcoae to DISTEL iC Display Electronics 1981 Control amp Q can be used to slow down output for reading W For HELP FILE Recomaended for first tiae users D For DISTEL including sailing list and topical info J For DISTEL sain senu Enter Cossand H Use Control S and Q to stop and start data output The DISTEL data base contains a lot of inforaation READ this help file to enable you to sake the best use of it Good Luck All data roa the DISTEL coaputer is selected by an 8 choice MENU Menu explanations 1 SEARCH Data base by GENERIC part nusbers A lot of aanufacturers aake similar itess and identify thea by alpha prefixes For exasple an SN7400 would be found by 7400 Reaeaber the FEWER digits you enter the MORE items you list 2N entered on its own will list a lot of transistors 2 SEARCH Data base by TYPE of Product for exaaple PRINTERS DISKS POWER SUPPLIES TRANSISTORS etc The GENERIC search still applies so the less you enter the aore types of product headings you will see Enter the 3 digit category nuaber to see all SUB categories under the chosen heading Full naaes of PRODUCTS are NOT required DISTEL will search tros just single characters SEARCH by RS Components catalog number We stock a LOT of itens that atch or exceed the spec of RS items The only difference is the PRICE Itess say be found by entering the RS part nuaber ie 208 5657 reaeaber to
18. 1299A oleo C1134 3200 EC93 150 EL519 6 95 sop 695 PY32 0 60 TB2 5 3000 2359 9 00 5A 206K 10 00 EFEG 2 00 12HG7A 4 50 1619 2 50 C1148A 115 00 EC95 7 00 EL802 3 65 MS02A 6000 PY33 0 50 60 00 Z505S 15 00 SAMB 2415 arte 150 12J7GT 0 70 1625 3 00 G1149 1 130 00 EC97 110 ELB2 850 Meo8 85 00 hYB 070 TB2 300 4500 29204 00 Sane 120 SFI2 159 12ks 00 1828 300 amp 1120 113600 ECHOT0 1200 ELO22 1295 Mes a 60 00 PYS2 070 TDI T00A DR OR cans 20 eto 12K7GT 0 60 2050W 950 C1534 32 00 li j Y83 0 70 z 5 1 1 10 205 Hi Sca 2f ecca gso Ems aoo Maora em Pyae 965 Toma 2748 960 Bno wooo f P5 Mer ose Me am ECI 0 90 ECC35 3 50 M8082 7 50 PY500A 195 800U 3 00 i 5 6F22 0 70 12SA7GT 1 00 4313C 4 00 CL33 2 00 1 a5 EMB 0 70 PY800 0 79 TD03 10E 58 255M 19 50 12887 475 4328D 900 COCHE 03S ENSE JS Mei ase CaO oon Eoo em eaey aoe gn te m MUERE onrequest ECC82 Philips M8096 3 00 13 11 ZA1 i i 6F25 1 25 29K7 100 5651 2 50 D63 1 20 EM87 250 47 50 28 00 A1001 1 50 5B 258M 14 50 1287 0 60 5654 1 95 DAF9 070 eccsa oes ENIO 8 00 M8098 550 Qe 299 goso TO3 2 400 2A100 150 5C22 4000 aes 128 12SN7GT 1 85 5663 19 Barge 086 ECCH3Brmar ENS 1380 maioo sso OtO310 350 Ir2s 150 ZO eos oos zao G3 re 2SQ7GT VS0 5670 3 DC70 125 Mullard 1 35 M8136 700 EO8 oo 6FGS
19. 2N2906A 30p 3N140 200p TRIACS 74132 60p 74L8153 70p 745140 60p 4521 125p v 7806 40p 7906 45p 7N1034E 200p BFR96 180p TIP32A 45p 2N2907A 30p 3N141 200p PLASTIC 74136 amp 0p 74LS154 250p 748151 180p 4522 30p gy 7808 50p 7908 50P ZN1020E 200p BFX29 45p TIP32C 40p 2N2926 12p 3N20 200p 74141 90p 745155 70p 745153 180p 4526 930p 15y 7812 40p 7912 45P 7NA134 23 BFX30 45p TIP33A 70p 2N3053 36p 3N204 200p 3A400V 60p 74142 225p 74L5156 70p 745157 250p 4527 930p 15y 7815 40p 7915 45P ZNA234 950p BFX84 5 30p TIP33C 80p 2N3054 60p 40290 250p 5A400V 70p 7443 250p 74LS157 70p 748158 195p 4528 75b 18V 7818 50p 7978 50p BFX86 7 30p TIP34A 90p 2N3055 55p 6A500V 88p 74144 250p 74LS158 70p 745163 300p 4529 30p 24V 7824 40p 7924 45P eymar BEX88 30p TIP34C 120p 2N3442 140p 8A400V 75p 74145 90p 74LS160A 90p 749174 250p 4531 75p sy 100mA 78 05 30p 79L05 45p Malsidbdlu BFX89 180p TIP35A 120p 2N3553 240p DIODES 8A500V 95p 74147 120p 74LS161A Sop 749175 320p 4532 80P GV 100mA 78106 30p BFY50 30p TIP35C 140p 2N3584 250p py 27 132p 12A400V 85p 74148 120p 74LS162A 90p 749188 180p 4534 400p gv 100A 78108 30p AD161 2 45p BFYS1 2 30p TIP36A 140p 2N3643 4 48p BYx36300 20p 12A500V 105p 74150 150p 74LS163A 90p 748189 225p 4536 220p 12V 100A 78L12 30p 79L12 50p BC107 8 18p BFY56 33p TIP36C 150p 2N3702 3 16p gaa 1
20. 74176 90p 74L 240 120p 749373 400p 12416 309P ORP61 120p TLIO 75p BCS57B 14p MJ4502 400p ZTX300 18p 2N5191 890p 74177 75p 74 5241 120p 745374 400p 14419 300p 8C559C 24p MJE340 60p ZTX452 45p 2N5245 40p 1A 50V 19p 74178 120p 74 9242 075p 749387 225p 14490 550p OPTO ISOLATORS BCY70 30p MJE2955 150p ZTX500 20p 2N540 60p 1A 100V 20p 74179 120p 74LS243 75p 742472 475p 14495 450p P5 130p TILTI 70p BCY71 36p MJES055 120p ZTX502 20p 2N5459 30p 1A 400v 25p Lus ALIO 74180 70p 74LS244 300p 74557 300p 14500 700p crag 100p TILII2 70p BO 3 75p MPF102 40p ZTX504 22p 2N5460 80p 1A 600V 30p RELAYS 74181 180p 74 S245 350p 745573 500p 14599 350p Pc Ar 190p TIL113 70p BDI32 80p MPF103 4 40p ZTX552 55p 2N5485 36p 2A SOV 30p 74182 75p 7aLS247 70p EONI 22 0 2005 MOC3020 150p TiL116 70p 8D735 6 40p MPF OS 40p ZTX652 60p 2N58 5 250p 2A 100V 35p 74184 180p 74LS24B 70p 4000 30p 2202 Joop LO7 1o 6N137 4000 BD139 40p MPSAOG 30p ZTX 52 7p 2N5883 375p 2A 400v 45p SO OTSA 5 P 74 8249 70 f P P 2N697 35p 2N6027 30 V 60p 24190 sop 7418251 70b aoo 305 400 48p MANI Jaep BD189 60p MPSAI3 Sop 2N698 45p 2NB052 300p 3A 600v 72p 24V0C 360p 74191 90p 74LS253 70p 4006 gop 40085 90p MAN 4 140p B0232 60p MPSA20 50p 2N706A 36p 2N6059 325p 4A 100V 95p Sor VOC 74182 90p
21. C200 Bench model 47 digit 0 2 I pf to 2500mtd 6 ranges UK C P 85p 89 00 DIGITAL THERMOMETERS Pocket size LCO thermometers complete with battery Accept any type K probe UK C P 65p TH301 LCO 50 Cto 750 C 1 Cresolution with thermocouple 59 50 TH302 LCD 40 C to 11007 C Cent Fahrenheil 0 1 and 1 resolution with thermocouple 79 50 Range of various probes in stock 17 50 to 25 00 COMPONENTS ACCESSORIES tric TOOLS Large range in stock semiconductors relays tools Plus millions of capacitors resistors presets controls plugs sockets etc etc For bulk export users Fel 01 723 1008 with enquiries OTHER EQUIPMENT IN STOCK Send SAE for full specifications UK C P 1 50 UK C P 1 00 LHC 909B VHS BETA video head tester 45 00 OM358 Scope multiplexer 35MHZ expands any scope to eight channels 169 00 LTC905 Scope add on semicon curve tracer 99 00 LCT908A Transistor tester all types 109 00 LTC907 Transistor tester signal injector tracer 178 00 LVT72 FET VOM transistor tester 143 00 LCR740 LCR bridge cap inductance and resistance 195 00 LDM170 Distortion meter 20HZ to 20KHZ 310 00 LFG1300 Sweep 0 3 function generator 0 002HZ to 2MHZ 395 00 TC40 VHF UHF FM and TV lield strength meter Battery operated with carry case 177 00 MC321 UK PAL TV colour pattern generator 222 60 MC32B As above but Secam B 6 H 222 60
22. GCIU 4B 17 50 OB 250 QS108 45 400 UBF amp 0 060 INSGT 250 6AQ5 150 6L7G 075 3ocig 148 6o59 375 DL93 110 gECugi oes GC10 4E 1750 O55 150 QS150 5 695 UBC4 175 182 955 6AQ8 0 85 6LD20 0 60 3of5 0 95 6060 225 DL94 250 ECH83 0 78 GC12 4B 17 50 O03 170 QS150 30 115 UBC81 150 174 0 70 6ARB 3 95 6LF6 PE 30FL1 1 00 6062 4 50 DL96 250 ECHes o69 GD86W 6 00 OW 109 Q 150 45 7 00 UBF89 0 60 105 100 Gass 4 50 6LO6 a 30FL2 1 35 6063 2 00 OLS10 13 50 ECH2000 150 GDT 20M 5 00 OMse 300 QS1200 3 95 UBL21 175 1X2B 140 6AS6 1 50 6N7 250 3orL12 095 6064 3 25 DLS 16 10 00 Ecigo oso GE10 9 00 Ome 175 QS1202 335 UCS2 120 287 150 GAS7G 750 SNUGT 150 3 FL13 110 6067 1 95 DM70 195 EC 82 0 65 GN4 6 00 ORpa3 259 QS1203 4 15 UCCBA 070 2C21 1 00 6AT6 0 75 6P15 150 30FL14 125 6072 4 20 OM160 275 1 GNIO 1500 j QS1205 395 UCC85 0 60 2C39A 23 50 eAT8 1 75 6P25 4 00 30L1 0 45 6080 475 ECL83 2 50 ORPSO 3 95 2C39BA 39 50 6P28 2 00 DY51 150 e taa 074 GRIOG 400 bei 250 QS1206 105 UCF80 1 00 6AU4 2 00 30L15 0 60 6080WA 8 50 DY86 87 0 65 ctes oeg GRIOL 400 pa 250 QS1207 090 UCH 2 120 2C40 3700 6 amp AUG 095 607 120 30L17 0 60 6096 2 85 DY802 02 tCig6 0 80 OGS 0C 1650 PABC80 0 50 QS1208 0 90 UCH41 120 2C40A 55 00 6Av6 0 75 6Q7GT 1 20 30P4MR 1 00 6132 10 00 EBOCC 850 E Leos 0 69 GS 0H 12 00 pege 0 75 QS1209
23. New features are the 64K byte of user memory a high reso lution c r t controller and a flexi ble i o section including interfac ing for 3 5 5 25 or 8in single or double sided single or double density disc drives Up to 32 lines of 96 characters or 192 by 192 pic ture elements may be displayed and graphics and characters may be mixed My disc operating system SciDOS see note at end of arti cle is compatible with most sof tware written for the standard 8 bit operating system CP M I have also designed software to make use of special features of the computer in particular the v d u These programs include utilities disc editors and an extended Basic interpreter Much of this software was developed in con junction with the Scientific Com WIRELESS WORLD MAY 1984 puter whose disc interface came later so users of the original com puter will find that their software runs on the SC84 with little or no modification SC84 reflects the shift towards microcomputers with most of their programming on disc rather than in read only memory The only rom in this design is an 8K byte eprom which on switch on or reset copies the resident operat ing system into random access memory ram and is then switched out leaving the system entirely dependent on ram There are two advantages in this approach Firstly having every thing in ram means that every aspect of the computer is open to experimentation Secondly while a
24. Thanet Electronics ag Thomson CSF 45 Thurlby Electronics cd Timebase Q Teq 88 TK Electronics 89 Triangle Digital Services eese 4 Valradio Power 17 Vellerman UK 4 18 Vigilant Communications a 92 XTR Electronics meote siae Pe AERE 73 OVERSEAS ADVERTISEMENT AGENTS France amp Belgium Norbert Hellin 50 Rue de Chemin Veat F 9100 Boulogne Paris Hungary Ms Edit Bajusz Hungexpo Advertising Agency Budapest XIV Varosliget Telephone 225 008 Telex Budapest 22 4525 INTFOIRE Italy Sig C Epis Etas Kompass S p a Servizio Estero Via Mantegna 6 20154 Milan Telephone 347051 Telex 37342 Kompass Japan Mr Inatsuki Trade Media IBPA Japan B 212 Azabu Heights 1 5 10 Roppongi Minato ku Tokyo 106 Telephone 03 585 0581 United States of America Jay Feinnan Business Press Inter national Ltd 205 East 42nd Street New York NY 10017 Telephone 212 867 2080 Telex 238327 Jack Farley Jnr The Farley Co Suite 1584 35 East Walker Drive Chicago lllionois 60601 Telephone 312 63074 Victor A Jauch Elmatex International P O Box 34607 Los Angeles Calif 90034 USA Telephone 213 821 8581 Telex 18 1059 Jack Mantel The Farley Co Suite 650 Ranna Building Cleveland Ohio 4415 Telephone 216 621 1919 Ray Rickles Ray Rickles amp Co P O Box 2028
25. bone of the Information Society cient monomode cables acceler it is instructive to consider the ated their use Such cables development rate of other tech started to be installed in 1980 nologies contending mainly with an interval of 14 years after the technical problems The telecom early work munication service infrastruc Many years passed before ture will be contending mainly Clarke s 1945 forecast that global with political and social problems communications using three which will greatly slow down the geostationary satellites would be growth rate ossible By 1980 satellites were In the July 1966 issue of Da being routinely used as relay Heading picture is an artist s tamationit was stated that econ stations in the United States In mpn Dn of an office in 2000 omies of scale are swinging this case it took 18 years for the A D of which the essence is increasingly in the direction of idea falteringly to be realised a comfortable simplicity There large computers and in a 1970 further 10 years before satellites isa large colour screen with issue of Computer Decisions became used as telephone relay voice control of the isplay Small businesses are not going stations in the Intelsat network The keyboard will probably to have small computers it snota and several more years for tv still be needed because practical way to go In 1972 it relay satellites to become com continuous speech recognition was
26. cuc 01 637 5551 or 01 636 9659 i 1 Test and measurement instruments design if fleuis l Digital signal processing Digital storage oscilloscopes CAPITAL APPOINTMENTS LTD i 2 Materials supply and control 29 30 WINDMILL STREET LONDON W1P 1HG Applications are invited from Honours graduates in an appropriate discipline and ideally with some industrial experience Associates have the opportunity to register for a higher degree Three posts are based at Wetherby and are initially for a two year period Salary range 6516 7692 CHELSEA COLLEGE UNIVERSITY OF LONDON Electronics workshop technician required for interesting work for electronics and physics research and teaching Includes prototype instrument design development and construction and the servicing and repair of commercial elec tronic equipment Find out more by ringing Andy Lamming on Wetherby 61961 or Harrogate 870643 after 7 00pm Further details also available from Personnel Farneil Instruments Ltd Wetherby L 22 4DH Experience and qualifications in electronics particularly digital at an appropn ate level are essential Inclusive salary Grade 5 7529 to 8582 p a Further details and application forms from Mr M E Cane Chelsea College Department of Electronics Pulton Place London SW6 5PR 2563 Careers in Electronics Research The Laboratories at Redhill Surrey are the UK research centre of the international Philips Group of Comp
27. fF Aca Sob aso Zane 100b 24 Female Female EE WAT HM LEE Audio output skt Supplied with Demo De IDC 15 way plug 340p Socket 400p 24 Male Female 9 50 2x32 way St Pin 230p 275p 2 7 way Vic 20 350p velopment programs and simple software IDC 25 way plug 385p Socket 450p 2 32 way Ang Pin 275p 320p 2 140p s 3 3x32 waySt Pin 260p 300p 2 175p 220p instructions 37 2 p amp p TEXTOOL ZIF DIL HEADERS 3x32 way Ang Pin 375p 400p 2 25 way 225p 220p SOCKETS 24 pin 5 75 1 DC Skt A B275p A C 350p 2428 way Specirum 200p s 28 pin 8 00 40 pin 9 75 Solder Type IDC Type fer 2x a2 way pease speciy spec BONN ps zt VIE Mpin 40p 100p ngt 33 peng 2x22 way 130p NEW COMPREHENSIVE COE AVAIL DIL SWITCHES eph ne wee 1 TEST CLIPS 25843 Ay 3956 4 70 8 130p 200 225 14 pin 37 pin 400 1 77 way 400p 500p ABLE PLEASE SEND FOR PRICE L TA way 1300 opim p AXI agin 4008 E WIRELESS WORLD MAY 1984 WWW americanracdiohistorv com EEE 74278 150 74LS293 75 80p ME 75 7115 100p E LINEAR ICs COMPUTER COMPONENTS MODA TORS P 74283 70p 74 50 w
28. fibres exhibit losses of around 2 5 to 3dB km at 0 85um and 0 7 to 1 5dB km at a wave length of 1 3um 1 Apart from the Rayleigh scat tering limit the main loss mechanism in optical is that due to OH water molecular excit ation as illustrated in Fig 4 For tunately advanced processing and drying techniques have brought these loss regions down to manageable proportions within th last five years or so although it is obviously wise to avoid the 1 4um wavelength of OH excit ation Optical sources such as l e ds and injection laser diodes i l ds covering these near infra red wavelengths will be described in the second part of the series It is instructive to compare WWW americanradiohistorv com typical attenuations for different technologies to illustrate the pot ential advantages of optical fibres for communication A twisted pair of 0 65mm wires has a typi cal attenuation of 15 to 20dB km at 1MHz increasing as f but crosstalk problems restrict their use at higher frequencies Coaxial cables require optimization for best attenuation figures with a value of around 75dB km bein common at 100MHz Optica fibres are clearly superior in terms of attenuation and in addi tion exhibit far higher band widths The maximum usable band width or bit rate for a communica tion link occurs when two adja cent but separate input pulses emerge from the far end of thelink smeared out in time to an extent that
29. full CP M disk system and much more Send SAE lor full leaflets NASCOM 2 kit NASCOM 2built ITT 2020 CABINET Prolessional computer case 18 x 153 x 41 Front slopes As previously advertised 23 91 UK C P 2 10 TOROIDAL TRANSFORMER 225 00 265 87 ntm 230 240V AC plus 8 0 BV 4A 15 0 15V 0 645 30V 0 16A THERMAL PRINTER COMPLETE WITH FULL HANDBOOK 3 ROLLS PAPER 43 43 IUA U f Li SUITABLE FOR TANDY BBC DRIC NASCOM GEMINI ACORN NEW BRAIN DRAGON ETC ETC interlace unit with leads 13 state model your enquiries invited size approx 4 dia x 1X 6 91 UK C P 75p LA gt 100 watts isolations PRESTEL KIT Complete set of PRESTEL adaptor cards Con ststing of main processor card with battery backed RAM modem card direct line coupler and keypad Outputs are composile monochrome and separate RGB Suitable for use with colour monitors or suitable TVs PS 12V and 5V ASCII KEYBOARDS Computer keyboards All models brand new QWERTY UK C P 1 00 All models 5V and 12V Amp P S 7 78 UK C P 6Dp 69SD5 Exclusive Special Purchase Compact 64 key hall effect 5 function keys ve ve strobe Normal ASCII but all definable Steel frame All facilities complete with plugs 30 43 SMK 69 Key general purpose steel plate Redefinable output Neg strobe pulse 4 user definable keys shift and control keys etc With connector Discounts for quant
30. further details send s a e to ABBEY AUDIO PO BOX 2 STAINES MIDDX TW18 2NH Tel Staines 0784 63319 2547 101 WWW americanradiohistorv com Classified ARTICLES FOR SALE SERVICES FOR SALE Marconi OE1761 Autotest compu FERROGRAPH RECORDER test set RTS2 and auxiliary test units ATUI for sale As new Tel 0385 882678 2565 FOR SALE IBM Selectric Golfball Printer Letter quality with centronics parallel interface In very good condition 160 Tel East Grinstead 25759 2551 FOR SALE MARCONI spacial purpose HF radio station type HS27 HR28 Military type D11 Complete with all manuals Tel Royston 71825 2554 RACAL COMMUNICATION RECEIVERS 500Kc s to 30Mc s iN 30 BANDS Mc s WIDE RAI MK 100 RAIL 150 RATE 225 NEW METAL LOU VERED CASES FOR ABOVE 25 EACH ALL RECEIVERS ARE AIR TESTEO ANO CALIBRATED IN OUR WORKSHOP SUPPLIED WITH MANUAL AND DUST COVER IN FAIR USED CONDITION RACAL SYNTHESISERS DECADE FREQUENCY GENERATOR MA3SOB SOLID STATE FOR USE WITH MAJS RAT RA21 RAI2U ETC 10010 150 MA2S0 16Mc s TO 316Mc s 100 to 150 MA2S5G PRECISION FRE QUENCY STANDARD SMe s 100kn 100 to 150 EDDYSTONE RECEIVER TYPE EC9b4 7K SOLID STATE SINGLE CHANNEL SSB MAINS OR BATTERY POWERED 1610 27 5Mc s AND 4QQ 535Kh E100 WITH MANUAL REDIFON SSB RECEIVER TYPE R499 SOLID STATE 10 FIXED CHANNELS RANGE 15 TO 30Mc s AND 255Khz TO 525Kh POWER MAINS DR BATTERY COMPLETE
31. leads etc D YF501 58 13 UK C P 855p ke j p i Test Equipment Audio Communications 01 724 3564 All mail to Cubegate Ltd Ist Floor 406 Edgware Road London W2 1ED WIRELESS WORLD MAY 1984 VARIABLE POWER SUPPLIES 220 240V AC UK C P amp ins 1 00 Bench portable all sine square triangle TTL etc External sweep mode FUNCTION Thandar TG101 0 02HZ to 200KHZ various facilities 105 00 Thandar TG102 0 2HZ to 2MHZ various lacilities 155 00 Sabtronics 5200A 0 1HZto 2MHZ 239 00 Thandar Pulse Bench portable TG105 5HZ to 5MHZ Various iacilites 105 00 Optional carry case 5 95 AUDIO Leader LAG27 5 band sins square 0 P 0 5V RMS Dist 0 05 10HZ to MHZ 93 00 Leader LAG120A 5 band 10HZ to MHZ to 0 3V AMS into 600 ohm 0 05 dist sine square 145 00 Leader LAG125 5 band 10HZ to 1MH7 to 0 3V AMS into 600 ohm sine square burst signals 0 03 dist 330 00 TRIO AG202A 4 band 20H7 to 200KHZ 10V AMS 0 P 0 5 dist CR OSC 0 10 pp 0 P 89 00 TRIO AG203 5 band 10HZ to 1 MHZ 0 t dist oI AMS 0 P 139 00 TRIO 6402 6 range 100KHZ to 30MHZ AF 0 1v RMS Int ext mod 72 00 Leader LS617 6 band 100KHZ to 150M HZ 96 to 450MHZ on Harmonics RF 0 1 V AMS Int ext Mod AF 1KHZ 1 volt 1MHZ Xcal optional 3 00 95 00 DIGITAL CAPACITANCE METERS Direct reading LED meters D0M6013 Pocket bench 8 range O 1pl to 2000mtd 3 digit 0 5 with battery UK C P 65p 52 13
32. oi resin and traces of metal abrasion Protects against erosion En sures perfect contacts Kontakt 61 Special cleaning lubricating and anti corrosion fluid for NEW non oxidised and specially sensitive contacts An ex KONTAKT cellent lubricant for all electrica and electro mechanical systems Spray Wash WL A rapid cleaner for reliable washing and degreasing of electrical equipment and components For removal of dirt grease oit soldering residues and other impur ties ALSO AVAILABLE A COMPLETE RANGE OF INDUSTRIAL AEROSOL SPRAYS SK10 Soldering Lacquer K75 Cold Spray K70 Plastic Spray K88 Oil Spray K701 Vaseline Spray K90 Video Spray K33 Graphite Spray K100 Antistatic Spray X101 Fluid Spray and of course Positiv 20 positive photo resist for printed circuits Details from Special Products Distributors Ltd 81 Piccadilly London W1V OHL Tel 01 629 9556 Telex 26500 answerback RACEN Cables Speciprod London W1 CIRCLE 033 FOR FURTHER DETAILS DC AC Inverters 30W up to 1kW sine wave or square POWER UNITS Eme WP ip Ee oe wi NOW AVAILABLE AC svi WITH 3 VARIABLE changers OUTPUTS Emergency standby systems No break systems Crystal controlled units Battery Chargers Input 200 250V 50Hz or 100 120V 60Hz to order Output 1 0 30V 25A D C Output 2 0 70V 10A A C Output 3 0 250V4A A C ALL CONTINUOUSLY VARIABLE Other units are also availabl
33. supplied for 240v operation complete with full circuit and tech man massive 5v DC at 17 amps 15v DC at 1 amp and 15v D8085AH 2 D8086 D8257 5 Cure those unnerving hang ups and data glitches caused D8202 D8271 AM2764 3DC by mains interference Give your system that professional finish for only 74LS86 74LS112 74LS373 SD5A As recommended by ZXB1 news letter matches 49 95 Carr Dim 19 wide 16 deep 10 5 high ze up to 1000 watt load Useable area 16 w 10 5 h 11 5 d 7497 2102 6 4116 3 2127 ompact completely cased unit with 3 pin fitted Also available LESS PSU with FANS etc Internal dim CALL SALES OFFICE FOR PRICES socket Up to 750 watts 9 99 Keep your hot parts COOL and RELIABLE SUPER PRIN TER SCOOP with rate range of BRAND NEW professional E 50 5 CASED Superb little unit made by cooling fans E HITACHI in ergonimcally designed free ETRI 9XUOI Dim 92 x 92 x 25 mm N BRAN standing case Very high delinilion will displa Miniature 240 v equipment fan complete with small but readable 132 columns wide 12v D M opp 800 ma so ideal for mobile use finger quard 9 95 x x2 The Do Everything Printer at a price that will i h GOULD JB 3AR Dim 3 x 3 x 2 5 compact Supphed in AS NEW condition complete wit very quiet running 240 v operation NEW 6 95 NEVER be repeated Standard CENTRONICS Sate Composite 75 ohm vid inp Black amp White BUHLER 69 11 22 8 16 v DC micro aae in
34. ters i e receive re broadcast links then almost certainly the alternative passive filter circuits are to be preferred To be continued Part 4 March issue In the inductor details for the Fig 34 circuit L should read 10uH not 5 Inductors 13 amp 14 not included on that list are 22uH Painton or Sigma chokes Also in that diagram please ignore the 60ns delay figure at DL and disregard the last five words in note 3 which refer to the phase equal izer C Ly Cj and Ly Capacitors 20 and 25 should be polystyrene types Apologies for the slip in the cap tion on page 32 where Tr should have read Tr y 10 WWW americanracdiohistorv com Fig 48 Television screen photograph showing similar effects of residual 7 8kHz at colour transitions caused by lack of amplitude and or phase symmetry in chroma path Such symmetry should be maintained because the V spectrum shifts on alternate lines see Fig 4 Dec 1983 issue also Fig 72 Fig 49 With an input of 10096 colour bars photograph shows screen with a minimum of cross luminance at colour transitions Colour bar generator was fed directly to the comb filter Fig 34 circuit Fig 50 Conditions as for Fig 49 but with inclusion of the transmitter and receiver tuner plus i f section in the signal path Results are still better than a luminance notch decoder only but the possible improvement compared with Fie 49 conditions is about alf Mullard M991BD
35. the level exceeds 43dBm A matching transformer pro vides coupling to the telephone line and the necessary degree of electrical isolation On e line side of the transformer the modem must also include a d c path to hold the telephone line once it has been acquired To allow automatic answeri of calls the Am7910 has a RING input This may be forced low by a signal derived from a ringing tone on the line whereupon it will switch the modem into an answer sequence If the modem is on line it responds with a period of sil ence at the TC output 1 9s under pur pan regulations followed by a few seconds of answer tone e call is then established and data can be exchanged between the computers at each end Regulations Potential constructors should be aware that the telecommunic ations authorities in Britain still place heavy restrictions on what may be connected to a public tele phone line Direct coupled modems have to be approved by the British Approvals Board for Telecommunications which unfortunately can only examine finished equipment Even so man commercially manufac tured modems available to the home user are not approved even though they may include compo nents designed to meet the offi cial specifications What seems to worry British Telecom is the possibility that someone will accidentally con nect a telephone line to mains electricity This could happen in a modem through faulty construc tion and m
36. tollowing produc ts is ST26A 6880AP 078 9845 DS 588 RO3 2513U Dl 782 arnedin stock and is BT28A 6889 078 6850 D2 131 SN75107BN 058 listedin eur FREE 8T95 6885 078 6862 000 SN75IIDAN 088 catalogue 8T97 6887 078 6871 Al 1417 SN75150P 072 8T98 6888 078 68488 D2 78 SN7SISAN 087 6875 713 SN75159N Lig MLS Senes TTC 68B00 D7 430 SN7SI60AN 215 enes Data Corivertors I tanga D6 936 SN7SISIAN 235 TI Bipolar Memones UpD7002 Di 465 68B21 D3 188 SN75162AN 331 9900 Senes Micros ZNA2SE 8 D 313 amp 8BIO DI 180 SN 75172NG 164 Crystals ZN426E 8 Dl 167 98840 D4 550 SN75173N 121 IDC Card Edge amp ZNAZ7E 8 DI 575 88B50 D2 183 SN75174 164 D Type Connectors ZNAO0F 8 DI 438 MC68BS4P 775 SN75U7S 121 Dip Jumpers ZN429F 8 DI 153 SN75182 062 Monochtome amp ZN432C 10 D12538 Z80 Family SN75183 062 Colour Monitors ZN432E 10 11088 ZIOA CPU D2 242 N75188 044 INECAKAGA ZNA3iC l0 D1209 ZBOBCPU pI 778 SN75189 044 Eprom Programmers 2N440 Di4943 BOACTC DI 220 SN7S4S1BP 024 amp Erasers ZNAC D670 zaoBCTC Di 778 SN79452BP 024 Custom Cable ZNAB Di 75 Z0A DART Dl 5so SN79453BP 024 Assemblies ZN449 Di 235 Z0ADMA D2 695 ZN441 D14032 Z80A PIO DI 220 Z80BPlO Dl 778 Crystals Z80SIO 0 D4 850 cariage Ord E 1 AUBIN 422 BOR SIO0 D4 900 uiage Orden up 1 E199 are sent by Lat class Al2A1008MHz 342 Z80BSIO 0 D42978 Pes sna EAN t AMZAIQONM A 280 ZOSIO 4
37. vacuo For a typical fibre with an index step 0 01 and a core refractive index n 1 5 then T nax 50ns km The pulse smearing caused by this delay spread is equivalent to a modula tion bandwidth length product of around 5 to 10MHz km In other WIRELESS WORLD MAY 1984 words due to modal delay spreading a lkm fibre of this type would exhibit a usable modula tion bandwidth of 5 to 10MHz One method of reducing the modal delay spread in a multi mode fibre is to make the refrac tive index of the core graded rather than stepped refer back to Fig 2 b Rays propagating in such a graded index fibre have nearly equal delays as the higher mode zig zag rays now take a hel ical path keeping to the outer regions of the core where the refractive index is lower and hence the speed of propagation faster By choosing a suitable index profile usually parabolic the modal delay spreading can be reduced by two orders of magni tude or more relative to multi mode step index fibres Figure 6 shows how the modal delay spreading varies with refractive index difference A for both step index and graded index multimode fibres at a wavelength of 0 85um To achieve the best compromise between bandwidth and source coupling efficiency it is usual for most multimode fibres to have a A value of around 0 01 producing typical modal delays of 50ns km and 0 3ns km for step and graded index fibres respect ively This corresponds
38. what he means by simultaniety and it is clear that it depends on what an observer perceives But he is still being haunted by the aether ghost of his own and his contemporaries early training and worried that the velocity of light might not be the same over the two equal but opposite dis tance A M and M B After what for him is a longish discus n he concludes his own ital ics That light requires the same time to traverse the path M as for the path B M is in reality neither a supposition nor a hypothesis about the physical nature of light but a stipulation which I can make of my own free will in order to arrive at a definition of simulta niety WIRELESS WORLD MAY 1984 a Yee 73 MODERN PHYSICS T m Now a stipulation arbit rary and subject to one s own free will in order to arrive at a defini tion does not seem quite the same thing as a universal natural law Is he not still talking about the velocity of light in vacuo And incidentally why should the definition or fact of simultaniet be associated so particularly ath light signals Could one not equally well send timing informa tion through a vacuum by means of calibrated bullets fired from calibrated guns at velocity u Of course one could not use cali brated carrier pigeons because they fly relative to a medium air But since he needs to differ entiate between the behaviour of ph
39. 010 FOR FURTHER DETAILS TRANSFORMERS ex stock MAINS ISOLATORS 50 25V or 25 0 25V 30 15V or 15 0 15V Pri Sec 120V x2 2x25V Tap Secs 5 7 8 2X15V Tap Sec Volts Price 10 13 15 17 20 25 30 3 4 5 6 8 9 10 12 15 5 82 33 40 20 0 20 or 25 0 25V 18 20 24 30 or 15 0 15V 50V 25V Price P amp P 30V 15V Price P amp P 1 443 140 05A 349 4 869 184 432 6 1036 190 6 99 242 8 10 2 20 9 67 20 11 95 3 00 13 52 3 20 18 10 20 88 23 20 26 60 35 64 AUTOS INVERTERS 159 27 154 93 239 50 1000W 350 00 2000W 709 00 CONSTANT VOLTAGE TRANSFORMERS Spike free stable mains 120VA 250VA 500VA 1kVA 100W 250W 500W Happy Memories 1 off 1 25 4 95 4 20 Call Call 3 85 4 20 3 85 Call Call P amp P 1 60 1 80 2 00 2 25 2 64 2 70 2 95 3 70 4 00 470 5 10 OA 0A o NOSTAN 25 99 1 15 4 40 3 75 Call Call 3 45 3 75 3 45 Call Call Part type 4116 200ns 4164 200ns 2016 150ns 6116 150ns Low power 6264 150ns xx 2 TAG edo et 2732 450ns Intel type 2532 450ns Texas type 2764 250ns Mes 271128 SD TISi auctis ntm PR ato j Z80A P10 2 99 7805 reg 0 50 100 up 1 10 4 20 3 60 Call Call 3 30 3 60 3 30 Call Call 2 99 0 50 22 172 193 69 336 40 2kVA 594 50 5kVA 1587 AVOs amp MEGGERs 8 Mk5 latest 140 70 73 78 90 MM5 Minor 52 00 DA212LCD 98 60 DAT16LCD 154 50 DA117 Autora
40. 1437 and TP 1438 operational amplifiers offer a 40MHz bandwidth with a slew rate of up to 400V us Both need only 200pA offset bias currents offer 95dB open loop gain and 0 5mV offset voltages A true differential input is designed to ensure a reliable performance whether used in inverting non inverting or differential configurations 1437 has a guaranteed 20mA output and is packaged in a T099 can while 1438 in a T08 package has a guaranteed 50mA output Typical applications include current to voltage digital to analogue converters pulse amplifiers radar and sonar signal processing and video systems Available from MCP Electronics Ltd 38 Rosemont Road Alperton Wembley Middlesex HAO 4PE WW 217 WIRELESS WORLD MAY 1984 NEW PRODUCTS PROGRAMMABLE MAINS SWITCH CAN SAVE ENERGY A control system which uses mainsborne signalling the Datapath can switch up to 256 remote mains powered appliances The manufacturers see the main purpose of the system as switching heating and are therefore promoting it as an energy saver though there are a nuber of other applications including the switching of security appliances and lighting It can be used for controlling contactor or switchgear The signals only provide for on off controls but local e g thermostat control is possible foreach remote site The control unit includes a microprocessor a real time calendar clock and a transmitter for sending the f
41. 2 50 XG2 6400 SR4GY 3 50 6F28 1 60 19H5 47 50 5751 4 00 BK448 114 90 2 50 EH90 1 75 KT77 Gold Lion PCC806 1 60 RG3 250 32 68 141 90 SU4G 300 6F33 33 50 24B9 67 25 5763 4 50 BK484 155 35 2 00 EK90 1 50 9 00 PCE82 2 00 RG3 250A 32 68 XG5 500 26 60 SU4GB 2 50 6HI 14 00 30C15 2 00 5814A 4 00 BS90 58 00 4 00 EL32 2 50 KT88 15 00 PCF80 2 00 RG3 1250 59 50 XG2 6400 5v4G 2 50 6H2N 2 75 30C17 2 00 5840 4 00 BS8 0 60 00 1 50 EL33 4 00 KTW6 2 50 PCF82 1 50 RG4 1250 61 60 162 00 SY3GT 2 50 6H3N 2 75 30C18 2 00 5842 12 00 BTS 58 95 2 50 EL34MUI 3 00 KTW62 2 50 PCF86 2 50 RG4 3000 99 45 XR1 1600A 523 4 00 6H6 3 00 30F5 1 60 5876A 31 50 BTI7 151 00 250 EL36 250 KTW63 2 50 PCF87 2 00 RR3 250 40 00 53 75 5Z4G 2 50 6j4 5 50 30FL1 2 1 38 5879 5 00 BTI9 44 05 1 50 EL4l 2 80 M8079 12 34 PCF200 3 25 RR3 1250 45 75 XR1 3200 81 97 5ZAGT 2 50 6J6 8 93 3OFLI2 1 80 5886 15 00 BT29 349 15 1 25 EL42 2 50 M8080 8 25 PCF201 3 5 SIIEI 65 00 XRI 3200A 630L2 175 6 7 4 75 30FLI4 2 00 5963 2 50 BT69 354 80 1 50 EL81 5 25 M8081 9 82 PCF801 2 50 130 6 00 XR1 6400 6AB4 1 5 6K4N 2 50 30L1 1 50 5965 3 50 BT95 129 90 1 75 EL83 6 00 M8082 9 69 PCF802 2 50 S130P 6 00 102 00 6AB7 3 00 6K6GT 2 75 30L15 2 00 6005 2 25 CBL31 4 00 1 50 EL84 2 25 M8083 8 58 PCF805 1 70 STV 280 40 YD1120 395 00 6AC7 3 00 6K7 3 00 30LI7 2 00 6021 4 50 CL33 4 00 4 00 EL86 2 75 M8091 10 43 PCF806 1 70 14 00 YD1240 450 00 6AF4A 4 25 6K8 3 00 30P4 2 50 6087 10 23 C
42. 20 50 o0 48 30 708 00 15 50 24 00 19 00 65 17 61 10 17 14 18 25 18 35 110 144 80 70 50 00 ao 80 o0 00 250 215 215 14 72 95 00 50 50 oc o0 50 144 24 16 24 22 6085 50944 6101 6130 24 50 6146A 7 50 61468 7 50 6155 49 00 6156 59 00 61598 12 50 6201 650 6227 12 95 6267 175 6293 14 00 6360A 5 50 6426 1690 00 6442 18 00 6484 32 00 6528 48 00 8550A 725 6688 8 50 6689 925 6693 90 00 6179 19 50 6856 52 50 6857 66 80 6858 99 20 6859 103 50 68838 14 20 6922 3 90 6939 19 50 6973 370 6975 66 00 7014 44 50 7015 50 00 7017 66 50 7018 18 50 7022 66 80 7023 103 50 7025 2 50 702 1 60 703a 42 50 7056 250 7136 17500 7189A 2 40 7199 420 7203 NAT 3950 7203 EIM 49 00 7233 575 7234 72 50 7247 3 2Q 7289 39 00 7308 7 50 7322 604 00 7360 9 00 74B6AL 80 00 7527 73 30 2527A 140 00 7534 23 50 7543 200 7551 550 1558 9 50 75B A 18 25 7586 11 50 7587 19 00 7591A 5 00 7723NE 28 65 78 5AL GE ag 00 7815A AL 48 00 7868 4 20 7903 15 00 7905 13 50 7984 13 50 8008 18 80 8020 35 00 6032 a 20 8056 15 00 8068 13 00 8072 69 20 8117 165 00 8121 90 00 8122 90 00 8163 82 00 8164 298 00 8233 44 00 827 39 00 82954 50 8321 EIM 10 00 8321 AMP 68 00 8416 157 8417 555 8422 20 00 8438 80 00 t4 20 280 00 2 50 66 70 1735 2330 06 65 Oc 55 00 9 50 6 00 120 00 9950 a 64 18 00 DEVICES 20PE11 25 00 20PE13A 2 00
43. 20PE14 25 00 20PE15 220 00 20PE19 25 00 20PE20 27 50 xQ1275 237 00 xa1276 262 00 3848 25 00 7262A 26 00 77358 26 00 8541 33 00 Baas 23 00 9677M 31 00 Ultracons price on sppilcation Otner types of Vidicon available Newviconsand Telephone 0376 27117 24 hour Ansaphone Service Telex Hay Lane Braintree 42494 987911 Essex CM7 6ST DISTRIBUTOR FOR RICHARDSONS ELECTRONIC EUROPE LTD R F POWER TRANSISTORS Many other types available 2N3375 2SC1120 25C2290 MRF428 SD1019 24 170 2N3553 2 25 112 2802347 MRF428A S010195 2a 70 2N3632 10 2501122 18 00 25c2369 2 00 MRF433 16 21 501020 150 2N3733 13 28011628 090 2 C2370A 18 00 MRFA49A 14 95 SO01074 16 10 2N3866 o 28C1165 6 95 282379 15 00 MRF450 11 90 SD1076 18 50 2N3926 11 2SC1169 4 85 25C2395 15 00 MRF453 11 90 501077 60 283927 T 2801176 14 00 25c2407 00 MRF453A 16 90 S0 1074 26 50 2N4416 075 2scv7 17 25 25C2420 18 00 MRF454 2 00 01080 155 2N4427 o 75 25c1178 18 00 25C2494 16 00 MRFA54A 23 0C 501080 6 7 50 2N5090 43 90 25C 12090 0 64 2SC2509 6 00 MAFa55 16 00 501080 7 7 50 2N5109 2 00 25C1213A 0 40 2sc253 1 30 MRF455A 21 00 S501088 26 00 2N5160 4 80 2SC1213C 040 25c2538 10 MRF458 19 95 501089 28 50 2N5190 1 50 28C1239 2 50 28C2539 15 00 MRF466 24 50 501089 a0 10 2N5589 6 00 25C1241 15 00 2Sc2540 24 95 MRF472 1
44. 3 50 cans all sizes 0 40 VCRI39A 8 00 7420 018 7453 018 7493 0 60 74128 0 68 7473 1 42 TAA700 3 90 7422 0 20 7454 018 7494 082 74132 022 74174 1 60 TBA480Q 1 84 Terms of business CWO Postage and packing valves and semiconductors 50p per order CRTs 1 50 Prices excluding VAT add 15 Telephone 01 677 2424 7 Price ruling at time of despatch j i g x Telex 946708 in some cases prices of Mullard and USA valves will be higher than those advertised Prices correct when going to press E amp O E Account faci s available to approved companies with minimum order charge 10 Carriage and packing 1 50 on credit orders Open to callers Monday Friday 9 a m 5 p m Over 10 000 types of valves tubes and semiconductors in stock Quotations for any types not listed S A E ANS CIRCLE 047 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com Ga nn Sees Ai SE E SUME cmn M B aca dE 0 9 toms ms WHAT RESOLUTION FOR ONLY 230 Our RGB high resolution colour monitors 580 x 470 pixels sell for 229 95 excluding VAT a saving of over 100 compared to other leading monitors of similar specifications Thatsa bargain we guarantee you won t see from any other micro retailer We ve managed to acquire the sole distribution rights enabling us to offer these superb monitors at this unbeatable price And just because vou re saving on price doesnt mean youre sacr
45. 406 TEK 465 Dual Trace 100MHz Delay Sweep 950 407 GOULD ADVANCE 053300B Qua Trace 5 0MHz Qual Time Base 450 408 TELEQUIPMENT D83 Qual Trac 50MHz delay Sweep Large Scrver 450 409 TELEQUIPMtN 075 Dua Delay Sweep 400 376 TEK READOUT SCOPC 567 with 6R1A Digital Unit 3S1 Dual Trace Samplirg unit DC 15H2 and 3177A Sampi ing Sweep Unit Complete with 2 probes 500 3 HP 180A Dual Trace SOMI z Delay Sweep 400 11 5 E LABSSM 111 Dual ace 20MHe 200 SOLARTRON SCHLUMBERGER CO 40 dual trace SOMHz dual TB delay sweep 325 COSSOR CDU 20 dual trace 50MH delav sweep 250 SOLAKTRON CD1400 dual beam 15MHz 90 TELEQUIPMENT D43 dual beam 1SMHz 30 SOLAR RON CD 014 dual beam SMHz 60 STORAGE OSCILLOSCOPES PHILIPS PM3234 dual beam 10MHz 1 200 TELEQUIPMENT DME4 dual trace 0MHz 450 TEK 549 with 1A1 plug in dual trace 30MHz dual TB delay sweep 400 2 HP SIGNAL ANALYSER 54808 memory display with 5ABBB and 5485A Plug ins 425 MARCONI SIG GEN TF2002A S 10kHz 72MHz AM FM 475 MARCONI SIG GEN TF995A 5 15 220M Hz AM FM Nar tow deviation 250 MARCONI UNIVERSAL BRIDGE TF1313 0 25 250 MARCONI UHF SIG GEN TF1060 2 450 1200MH late style 150 MARCONI UNIVERSAL BRIDGE TF868 range 60 MARCONI WIDE RANGE OSC TF1370A 10Hz 10M Hz Sine 10Hz 100kHz square 95 MARCONI DEVIATION METER TF7SID M 4 1024M Hz late style 150 MARCONI SIG GEN TF995 3S 15 220MH AM FM 150 MARCONI AF POWER METER TF893A 20H 35kHz 75 MARCON
46. 50 810 55 00 AL60 6 00 EBF89 070 ELB 0 75 oso PL88 1 00 C1 2000 9 00 xhi 7950 equipment ems 160 12AY7 3 95 Bria 1295 ANI 1400 EBF93 095 ELB5 4 50 Tai 300 PL95 1 75 SD6000M 6400A 500 ee 075 12AZ7A 195 813 18 50 ARP 2 070 EBL 2 50 EL86 0 85 ga USA 9 00 P1302 1 00 45 00 8950 4CX350A 71 50 6CWA 725 12B4A 3 50 813USA 5950 AREA 128 XEBEZU 2000 YEF90 150 Kre amp GoldLion PL345 12 50 eee aso yes s ace 7228 eCvs 100 13BA6 190 833A 11500 ARP35 2 00 35 PL500 110 3 00 d 12BE6 1 05 866A 3 50 gies zoo cern 278 ras 070 vg PS PL504 115 SPa2 3 00 Y602 o 1200 4Gv7 225 6Dce 295 i9BH7A 2 50 872A 1300 BS450 67 00 EC80 950 EMS 1215 KTWe zs0 i500 195 550 3500 ray E Desa 7590 goas 33e 12816 175 873 60 00 BS810 55 00 EC81 7 95 KTW62 250 PL509 4 85 E i j 12BY7A 275 884 5 50 Yi1020 29 00 4X150A 25 00 6DQ68 250 BS814 55 00 EC86 100 EL183P 350 krwes 299 PL519 495 STV280 40 EES 250 12CX6 120 930 9 95 CIK 16 00 g EL360 7 95 PL802 595 11 95 YL1070 115 00 A152M 9 00 12E1 17 95 4 100 CA i600 ccs 190 ESO 140 ore 250 PLBO2T 350 sTv2s0 80 yt1071 108 00 sareax 1000 amp ESB 125 12614 2890 oes 100 C1108 54 95 i 5 P 820 2 95 D i 12GN7 3 95 958A 1 00 C126 7000 ego 59 ELSO9 525 L199 2K 95 PLs557 2950 SU42 495 2302C 1200 5a 180M 9 00 GEWG 180 12HG7 450
47. 5A Unit 211 Strattord Workshops ndon E15 2SP T l 01 555 0228 3 lines WW 6 CIRCLE 058 FOR FURTHER DETAILS STEREO AMIPILIFIEFR 4 MODULES 200 2 x 100 WATTS CH MAINFEATURES INCLUDE 1 COMPLETE 2CH CHASSIS 9 4 deas ut NEW Designs gt MAIN FEATURES Concepts INCLUDE SUPER SOUND Coming Soon FREE STANDING 2 OPENFRAME DESIGN Open Frame Power Supplies OPEN FRAME 3 VARIABLE POWER60 100w Also Available NOW Amplifier Drive Board 100 350w p 100 23 50 inc pp 1 WISH TO ORDER QTV sca 8 200 STEREO MODULES 48 50 EA M 300 MONOMODULES 43 50EA D 100 MONO DRIVER PCBE23 50 EA VISA ACCESS NO c een n ORCASH WITH ORDER TOTAL FORINFORMATION A4 S A E ONLY VARIABLE GAIN 4 TERMINAL BLOCKS 5 PRECISIONPARTS 5r LABSTYLE FRAME 43 50 inc pp 48 50 ic pp M 300 EX 200 OPTION TERMINALS EXTERNAL FITTED TO FHAME ADD 3 00 X T R ELECTRONICS TECHNICAL SERVICE EXPORTDISTRIBUTORS WANTED CUSTOMDESIGNS AND PACKAGING 335 HOLDENHURST ROAD 7 10pm WEEKDAYS PROFORMA OR C W 0 AVAILABLE TO SPECIAL ORDER BOURNEMOUTH DORSET 1i 6pm WEEKENDS OEM QUANTITY DISCOUNTS STATE REQUIREMENTSIN DETAIL BHB8 8BT PH 0202 309872 01 573 1566 ALL ENQUIRIES SEND A4 SAE WW MAY 84 CIRCLE 068 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 73 WWW
48. 72 95 69 19 29 13 18 18 15 MOX UU 100 38 62 58 104 225 75 50 50 oo 50 50 00 00 88 50 00 00 oo 00 50 BO 00 so 00 8388 50 a5 95 30 50 00 50 50 50 00 40 50 50 50 15 15 65 10 50 45 95 95 50 50 95 oo 00 00 50 o0 10 o0 40 ad 50 50 o0 o0 50 00 00 75 so 66 34 so 00 00 EIM AMP NAT EIM A ag 39 o 68 72 440 o 785 7 64 o0 50 00 0 oo o X 50 75 00 5 00 24 128 535 17 6 ao NN kN UNH 50 o0 o0 o0 o0 oo 5 90 00 50 o0 75 90 50 90 30 95 95 80 10 95 70 95 90 20 85 50 20 so 6AVE 1 30 6AWBA 265 saza 380 58A8 1 60 6BABA 275 6BE6 1 90 5BH5 200 68J6 1 85 68K4C 445 6816 68 50 6BL7GTA 3 80 6818 145 68M6 93 95 68M8 1 50 6BNB 2 45 6BQ05 1 60 6BRBA 295 6BX6 1 35 6826 2 50 5C4 1 85 6caa 165 SCA 350 6C86A 1 90 6CF6 190 6CG7 225 6CHE 995 6CJ3 2 30 6CJ6 10 95 6cK6 6 00 6CLE 3 30 6CMS 230 6CN6 a 95 5coe 2 20 6cwa 6 50 6Cws 195 6CY5 3 80 6cy7 3 00 6czs 315 60A6 230 60C6 245 60C8 50 6038 170 60K6 395 6DT5 230 6DWAB 230 6E5 4 20 GEAB 245 6EHS 165 6EH7 2 00 6EJ7 200 6EL4A 315 6ES8 210 6EV7 2 85 6Ew6 50 6FG6 2 00 5FMB 16 50 6FO7 225 5FS5 225 6G85 2 80 6GE5 2 90 5GF5 210 6GH8A 80 6GJ5A 3 00 6GJ7 1 85 6Gk6 95 6Gwa8 rc 6Gx6 300 6GY6 3 00 5H5 3 ox 8HA6 3 05 6H86 3 05 6HES 4 00 6HF5 3 85 GHGS 9
49. 74 8256 200p 4007 3op 40097 amp 0p 0 125 MAN4640 200p 80233 75p MPSA42 50p 2N708 36p 2N6107 5p 4A a00v top CO DPDTS 74193 75p JALS257A 70p 40d 306 0 Sop TiL209 Red T0P MANB910 250p 80235 85p MPSA43 50p 2N918 45p 2N6247 190p GA 50V Bop 24 Rc 200 74194 60p 74LS258A 70p 4009 Bop 40100 120p TIL2i1 Gr 12p vo g 1409 BD241 60p MPSASG 30p 2N930 30p 22N6254 130p 6A 100V 100p Ms D 74185 65p 74LS259 120p 4010 6op 20101 120p TIL232 Yel 15P 716539 jan BD242 60p MPSA7O 50p 2N1131 2 50p 2N6290 5p 6A 400V 120p 6or 12V DC a 74196 60p 74LS260 70p aon sop 20107 aOR oo NS8588 s70 BD379 60p MPSA93 40p 2N1613 36p 2SC1306 100p 10A 400v200p Sol SFO 74197 90p 74LS26 90p 4012 30p ania Mg TIL220 Red 10p 110313 600b BD380 60p MPSUOG 63p 2N171 36p 2SC1307 150p 25A 400v 400p 540V AC 225p 74198 sop 74 8266 70p 4013 60p P t1222G 2p 113213 130p ERES Rd MPSUO7 60p 2N2102 70p 2SC1957 90p 7 p 74 9273 140p 4034 Bop MEMS 111228 Ye tsp ri330 140p Braden S05 MPSU45 930p 2N2160 350p 2SC1969 150p ELM 74221 74LS275 175p 4015 80p Rectangular 7750 60 200p i HA MPSU65 78p 2N2219A 30p 25C2028 80p 74251 74LS279 75p 4016 50p 74C925 4 LEDs IF G Y 30p Bargraph 225p 8E257 8 40P TIP29A 35p 2N2222A 30p 25C2029 200p 2 7V 33V 74259 74LS280 180p 4017 75p 74C926 5 g P BF337 30p TIP29C 40p 2N2369A 30p 2SC20
50. 74163 90p 74LS183 180p 748257 250p 4566 200p w723N 30p7SHGKC 700p 8C237 6P BU208 200p TIP126 80p 2N4036 65p IN4006 7 J 2A400V 160p 74164 90p 74LS190 75p 745258 250p 4568 300p ri 494 300piCL7660 250p BC327 16p BU406 145p TIP142 120p 2N4037 65p 1N5401 2 12p 6 100V 180p 74365 100p 7415191 75p 749260 70p 4569 200p 497 300p LM305AH 250p BC337 16p BUX80 600p TIP147 120p 2N4123 4 27p 1N5403 4 14p 6A 400V 220p 74166 120p 7ALS192 75p 74926 300p 4572 50p 75540 225p SG3524 300p 8C338 16p BUYGSC 350p TIP2955 30p 2N4125 6 27p 1N5404 5 14p C1060 45p 74167 250p 74LS193 75p 749262 850p 4583 75p BC461 40p E310 50p TIP3055 70p 2N4401 3 25p N5404 7 19p MCR 0 36p 74170 150p 74LS194A 70p 749283 300p 4584 48p Douala BC477 8 36p MJ413 250p TIS33 30p 2N4427 390p i5920 gp 2N3525 130p 74172 250p 7ALS195A 70p 749287 225p 4585 65P 2N5777 agp TIL32 55p BC516 7 50p Mj802 400p VNIOKM 50p 2N487 50p 2Na444 180p 74173 90p 74LS196 Bop 745288 180p 4724 150p OCP71 180p TIL78 55p 8C547B 20p MJ2501 225p VN66AF 90p 2N5087 27p 2N5060 30p 74174 90p 74 8197 7op 749289 229p 14411 750p Qgpi 50b TIL31A 120p BCS48C 12p MJ2955 930p VNBBAF 100p 2N5089 27p BILALL 2NS061 32p 74175 75p 74LS22 120p 45299 650p 14412 850p RPE 120p TL81 120p BCS49C 16p MJ3001 225p ZTX 08 186p 2N5172 27b Qaa 25064 35b
51. 850 0 100050 100 1991 25 200 5 00 hy Secencor All6A 24576MHz 100 Z80A SIO 1 D4 900 Pucesquoted 4 camage charges are exclusive of VAT and are subject to change without noti e A169A 36864MHz 155 Z80B SIO 1 A120B4MHz 085 Z80 SIO 2 A132A 6MHz 072 Z80A SIO 2 A140A BMHz 100 Z80B SIO 2 Quantity Discounts are available on many products please nng for details goug BESS Bow B83 A173A 9 8304MHz 140 MK3886 700 Official Orders ate welcome trom Education A182A 19 6608MHz MK3886 4 300 Establishments Government Bodies and Public 207 Companies 8080 Family Credit Accounts are available to others subject UHF Modulators 8085A D4 307 tostatus Paymentis due stictly nett by the 15th of ue evi alt 8212 150 the month 1 pale 137 Credit Cards are accepted Access and Visa lor Floppy Disc 8228 325 telephone and postal orders and NO SURCHARGE Controllers 8251A ps 260 maede 8271P 53 33 8253 333 Outol stock items will follow automatically at our FDI771P DS 2125 8255A DS 250 discretion or a refund will be given d requested FD1791 D6 1700 FDI793 D6 17 00 SPECIAL TELEPHONE NUMBER FOR FAST aial po235 Pa IMMEDIATE SERVICE TELEPHONE YOUR FDI797 D62435 Qa o TO DISS 0379 898751 WD 1691 D2 1200 WDp21430 D2 790 For FREE CATALOGUE posi to Midwich Computer Company Limited Prices all prices exclude V A T and Rickinghall House Hinderclay Road Rickinghall Suolk 1P22 IHH carriage Please add Nam these
52. BY223 0 90 INA148 02 A selection available wortage capability In consequence a large variety of amplifier load strategies can be BA145 0 16 BY298 400 0 22 IN 448 0 10 Prices on request implemente BA148 0 17 BY299 800 0 22 IN5401 0 12 As ever Pantechnic offer a full range of customising options including DC coupling BA154 0 06 BYXIO 020 IN5402 014 3BP 13 50 D10 210GH 45 ultra high slew etc Contact Phil Rimmer on 01 361 8715 with your particular BASS 013 ESE EULA INS403 012 DG7 32 42 DH7 9 59 application problem BAI 1015 9 INb404 0 2 DP7 6 35 DP7 11 35 P f BAIS 030 BYXS8 600H N5405 013 SEADP7 45 95447 135 P S Specs as ever are exemplary BAXI3 0 04 0 60 INS406 O3 M17 151GVR 220 ABS E 7 M T BAX16 0 06 BYX55 500 030 INS407 0 16 wide range of other amplifiers and other modules available 881958 030 BYXP 600 10 INS408 016 i ITT4A 0 04 Price and Delivery BY126 010 OA47 0 09 ITT923 0 15 TV SPARES PAN ECHNIC D Ww Technical Enquiries EH ae oat oe ITT2002 0 10 We now have available from ept w5 contact BY164 045 OA95 0 06 stock a range of popular TV Phil Rimmer 8Y176 1 20 OA202 0 10 spares including line output 132 HIGH ROAD A BY179 063 N9 4 0 04 TALSISERIES transformers tuners triplers NEW SOUTHG AT n BY182 055 IN4001 0 04 Sete etc LONDON NIT 1PC 01 361 8715 prist 1035 WES foes onrequest PRICE LIST AVAILABLE CIRCLE 066 FOR FURTHER DETAILS 90 WIRELESS WOR
53. Buffer Timer Card 24 inputs 16 outputs 4 timers Memory Card 24K battery backed RAM 24K ROM Real Time Clock Alex Assembler disassembler text editor amp monitor in a ROM Tiny Turbo compiles programmes to run at twenty times normal speed VDUs Memory Modules Cases Please send for full information WIRELESS WORLD MAY 1984 MODERN PHYSICS mn aoe The roots of relativity Dr Murray avoided criticising relativity theory in his recent Heretic s Guide series but here he makes good that omission by drawing attention to one of Einstein s very rare but crucial mistakes It is not unusual to encounter ref erences to the Special Theory of Relativity between the covers of Wireless World either in readers letters or in formal articles One interesting feature of these con tributions is that they are almost invariably critical of the theory although it is so thoroughly esta lished Why so It is true that the criticism comes from all sides so that cri tics will refute each others argu ments as hotly as they refute Einstein s for there exists as yet no singly accepted or re ceived argument in denial of Special Relativity Einstein s the ory is in every day practical use in modern physics and one is never apparently driven into error by employing it Pragmatically it works Nevertheless the fact that now some 80 years after its formulation a large number per haps even a ma
54. C P 659 ALL MODELS WITH CARRY CASE KD25C 12 range 0 2A 0C 2 Meg ohm S KD305 14 range 10A 0C 2 Mag ohm S 24 30 KD30C 26 range 1A AC 0C 20 n ohm A 29 13 ETE 3000 30 range 10A AC DC 20 Mag Inm 6010 2B range 10A AC OC 20 Meg ohm m Es KD55C 28 range 10A AC OC 20 Meg ohm A 34 c KD615 1B range 10A OC 2 Meg ohm plus Hfe tester A 34 74 7030 As 8010 but 0 1 basic PB 41 30 0M3350 Autorange plus cont tester 1B range 10A AC OC 2 Meg ohm A 43 02350 Min autorange plus cont tester 19 range 10A AC OC 20A Max 2 Meg ohm PB 54 73 K6330 De luxe autorange plus cont tester 23 range 24 43 All models BNC sockets Bench portables UK C P 1 00 PFM200A pocket counter C P 65p METEGR SERIES UK made 0 1HZ resolution 8 digit LEO display mains operated 220 240V AC switchable gate times MET1000 2 range 5HZ to 100M HZ 1 20MHZ typical 89 00 MET600 3 range SHZ TO GOOMHZ 700MHZ typical MET1 000 3 range 5HZ to 1GHZ 1 26GHZ typical Optional 6 x nicads 9 95 SABTRONICS New models LEO display switchable gate times 8110A 8 digit 20HZ to 100MHZ 79 00 8610B 9 digit 10HZ to 600M HZ 109 00 8000B 9 digil 10HZ lo 1GHZ 149 00 85008 9 digil up to 1 GHZ 239 00 THANDAR UK made LCO displays with batteries TFO40 8 digit 10HZ to 40MHZ LCO 1 HZ resolution 40mV sensitivity 2 gate times with batteries 120 00 TF200 8 digit 200MHZ LCO 2 ranges resolution Ippm 10mV AHS sensitivity 5 gate t
55. CB10 1EE Tel 0799 24922 Telex 818750 CIRCLE 054 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com GANG OF EIGHT The FAST eprom programmer NOT 4 S imove mhen red hg t is on When manufacturers recommended Fast Programming Algorithms can be used GANG OF EIGHT IS FIVE TIMES AS FAST AS A STANDARD PROGRAMMER This means you can program a set of 27128 s in 2 minutes not 14 minutes Or 2764 s in 1 25 minutes instead of 7 minutes GANG OF EIGHT will program all single rail devices from 2716 to 27256 with FAST or NORMAL algorithms All possible levels of programming voltage are covered even the latest 10 5 and 12 5 volt levels GANG OF EIGHT has SINGLE KEY OPERATION which makes life very easy for the operator It always performs VERIFY and BLANK CHECK operations automatically it won t let you program the same EPROMS twice or program EPROMS which are not blank In the FAST programming mode GANG OF EIGHT can produce several times the out put of a standard programmer FAST DELIVERY At the time of writing DATAMAN has more than enough stock to meet the expected demand for GANG OF EIGHT If you want confirmation before sending your cheque please telephone us with an order number and a GANG OF EIGHT will be packed and set aside for you Part of our value
56. DEC LA34 Uncoded keyboard with 67 quality GOLD normally open switches on shops etc Supplied in a used but working GREEN TEXT switch for high def text standard X Y matnx Complete with 3 LED indicators amp i o cable ideal micro applications and matching BBC colour Scheme make this monitor ideal for the most 19 w 16 d 10 5 h 19 95 Carriage amp insurance 9 50 ONLY 55 00 PLUS E9 50 CARR 6 INS ony Efe 00 810168 can SUPER DEAL NO SUPER STEAL SEMICONDUCTOR The FABULOUS 25CPS TEC Starwriter DATA M M Mixed Semis amazing value contents include transistors digital linear IC s triacs range of EX TELECOM data modems Made to f Made to the very highest fag uaranteed brand new full spec with manu most stringent spec and designed to operate f spec the TEC Starwriter acturer s markings fully guaranteed CCITT tone spec With RS232 1 0 levels via f heavy duty die cast TTL 74 Series A gigantic purchase of an a 25 way D skt Units are sold in a tested chassis and DIABLO type across the board range 0f 74 TTL series may be required for connection to PO lines Superb registration ard mostly TTL grab bags at a price which two MODEM 28 Hackers Special fully fledged print quality Micro or three chips i
57. Enabling Infrastructure are apt in the context of the information infrastructure generally For a new undertaking to be feasible the state of the ingredients needed for success must be con sidered A readiness potential exists when the development of those ingredients considered collectively seems to indicate that the time is ripe for launching the undertaking They include e processing technology hardware and software appropriate telecommunica tion facilities encouraging experimental work credible advocates and publicity optimistic forecasts apparent economic viability e apparent need markets Figure 1 shows the factors which then control success the factors with which the driving force a group of manufacturers or services or perhaps one only must successfully contend They seem to be e human factors associated with the use of machine e reliabilit standardisation compatibility success momentum e political reality e service infrastructure Success momentum conti nues if the earlier hot air can be backed up by success in practice with circulation of the good word favourable technical articles and reviews further purchases with wider usage etc Success breeds success Political reality means both concentration on the art of the possible and conducting oper ations which will take advantage WIRELESS WORLD MAY 1984 Privacy data protection transborder flow internati
58. London 14 Harrison Bros 24 Hart Electronics Kits 85 Henson R Ltd 20 Hibmast emg Houseof Instruments ccceeeeeeeeeneeeeenenes 2 IEP ElectroniGs 22 ove oon too e Sere iae rne sas 25 Integrex Ltd ei eee eir ere ee esee sita reis 18 A F Graphics eoe tee rro eot ren nac 92 JPR Electronics 5 casi diswasisocasteancdsvadvederas vice 85 Langrex Supplies Ltd esee 74 Levell Electronics er Light Soldering Development 16 92 Midwich Computer Co Ltd ssessss 9 Minim EIGCIFORTS Lose ubre died nb dind isina sisian 22 OlsonElectronics Opus Supplies Orion Scientific Pr DIntechrnie iiu sicecsancanasaad anaes sdvasccsudeseseanvaues PM Components Pye Unicam Radford Laboratory Radio Component Spec Radiocode Clocks Ralfe PF 3 Research Communication vs Reticon EG amp G 16 RST Valves eoe rere Pese er rende o rere 74 Solent Electronic Services esses 88 Service Trading Co Ltd 76 South Midland Communication 90 Sowter Ltd EA 18 Special Product Distribution 17 Stewart of Reading 76 Strumech Engineering 89 Surrey Electronics 14 Taylof Bro8 4 ne Osee eoo eR Tiv EROR PvE va Ed 88 Technomatic 86 87 Tektronix mm yi Thacker AH 20
59. MASTS Pneumatically operated telescopic masts 25 Standard models ranging from 5 metres to 30 metres E M S POWER SYSTEMS m Solve all your Power Problems by contacting E M S E M S specialise in systems to eliminate your power problems Products range from 35VA switched square wave Power Packs to 1KVA fully uninterruptible sine wave systems E M S also manufacture chargers which range up to 60 amps For further details please contact E M S Manufacturing Limited Chairborough Road High Wycombe Bucks Tel 0494 448484 CIRCLE 007 FOR FURTHER DETAILS the TDS900 into products Programme it with a VDU wa and your forecasts become fact im Software costs are signifitant in all industrial applications of microprocessors They cannot be amortised over the large quantities associated with personal computers and electronic games This C MOS embedded computer card aims at resolving this problem by including FORTH high level language programming and developmental facilities The software can be written quickly and made to work correctly at lowest possible expense Using a high level programming language rather than assembler gives a fast reaction time to market opportunities Production products use the same board as employed in the prototypes No microprocessor development system is needed since the card contains a screen editor working with simple visual display units VDUs It a
60. MHz UHF 701 30b 7a28s 225p 7aLS298 0p Sop AD75e7 i Lm36 90p SfFo636a oon MINE oo cn IG EIE GE UME f 1 1 Li Ei Bl E FI T 34 El Nc NE 7404 25p 74298 120p 74 8323 250p Sop AY 5050 99p LM39 180p SN76495 400p 2650A 12 9902 3 CRT6545 900p 81 598 120p FTA 7505 30p 74351 150p 74 5324 624200p 60p AY3 1270 750p LM392N amp 0p SP0256AL2 6502 400p TM 9901 350p CRT5027 18 88LS120 400p 7406 POA 743654 48p 74L5348 200p 90p AY3 1350 350p 3 100p me avon CEA 950p TMS9902 350p CHT5037 18 ae s et a2 TOBK oF POA 743664 60p 74LS352 100p 45p AY3 8910 400p 350p TA7120 150p 6800 P zB0P10 300p EF9365 36 9637 p 100p 7408 36P 74367A 60p 74LS353 100p 160p AY3 8912 500p 50p TA7130 160p 6807 300P 80AP10 350p EF9366 E36 ZN425E 8 350P iooKHZ 400p 7409 30P 74368A 60p 7418356 220p 40 80p LM710 50p TA7204 150p 6809 650P Z amp 0CTC 300p MC 845 650p ZN426E 8 350P 200KHZ 400p 7410 30p 74376 120p 745363 180 160p CA3019A 100p M711 70p 1A7205 930p 68809 12 Ze0Actc 350p MC68455P ZN427E 600P Freq in MHz ZAT 36P 74390 100p 7415364 180p 200p CA3028A 150p LM725C 300p TA7222 150p 6809E 12 Fenanany 750p ZN428E 8 450p 1 90 0 325p 7412 30b 74490 150p 7418365 55p 80p CA3046 70p LM733 75p TA73 0 150p 68B09E 16 850p MC6847 650p 18432 300p 313 40p JALS366 55b 270b LM74 20p TBA23 120p 6800 8 48 amp oA pA erp P8275
61. Miami Beach Florida 33140 Telephone 305 532 7301 Tim Parks Ray Rickles amp Co 3116 Maple Drive N E Atlanta Georgia 30305 Telephone 404 237 7432 Mike Loughlin Business Press International 15055 Memorial Ste 119 Houston Texas 77079 Telephone 713 783 8673 Canada Colin H MacCulloch International Advertising Consultants Ltd 915 Carlton Tower 2 Carlton Street Toronto 2 Telephone 416 364 2269 Also subscription agents Printed in Great Britain by Index Printers Ltd Oldhill Dunstable and typeset by Legendary Characters South Street Lancing for the proprietors Business Fress International Quadrant House The Quadrant Sutton Surrey SM25AS Business Press International 1984 Wireless World can be obtained abroad from the following AUSTRALIA and NEW ZEALAND Gordon amp Gotch Ltd INDIA A H Wheeler amp Co CANADA The Wm Dawson Subscnption Service Ltd Gordon amp Gotch Ltd SOUTH AFRICA Central News Agency Ltd Wiliam Dawson amp Sons S A Ltd UNITED STATES Eastem News D stnbution Inc l4th Floor 111 Eighth Avenue New York N Y 10011 104 WwwW americanradiohistorv com WIRELESS WORLD MAY 1984 EPROM EMULATOR PROGRAMMER EP8 amp 000 The new microprocessor controlled EP8000 Emulator Programmer will program and emulate all EPROMs up to 8k x 8 sizes and can be extended to program other devices such as 16k x 8 EPROMs Bipolar PROMs single chip microproces sors with
62. Multimeters Tektronix 3S3 Sampling plug in Telequipment D1010 Dual Trace Oscilloscope Many other items in stock please phone with your requirements All prices exclude VAT and carriage TIMEBASE F EC 94 ALFRISTON GARDENS SHOLING SOUTHAMPTON S02 8FU TELEPHONE 431323 0703 Callers welcome Access Barclaycard Telephone your order CIRCLE 025 FOR FURTHER DETAILS at MITSUBISHI MGF 1400 GaAs FETs MGF 1402 MGF 1412 FROM STOCK Aspen Electronics Limited UK representative for Mitsubishi Electric 2 3 Kildare Close Eastcote Ruislip Middlesex HA4 9UR Tel 01 868 1188 TIx 8812727 CIRCLE 015 FOR FURTHER DETAILS FILTERS Custom built to YOUR requirements Solent Electronic Services Ltd specialize in the custom design and manufacture of L C and crystal filters in the 0 40 MHz range 0 1000 MHz under development Filters are designed built and tested to meet the highest specifica tions including those for telecommunications and defence Production is specifically geared to small quantities from single units to small batches at relatively low cost Phone or write for further information Solent Electronic Services Ltd 15 Abshot Close Titchfield Common Fareham Hants PO14 4L7Z Tel 04895 82094 CIRCLE 013 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com eV FUNCTION GENERATORS The LEVELL TG302 is the lowest priced 2MHz function generator on sale
63. PCB Flow Soldering We buy large and small par cels of surplus I C transistors capacitors and related electronic stock Immediate settlement Tel 01 208 0766 Telex 8814998 2478 WANTED SJRPLUS ELECTRONIC COMPONENTS AND EQUIPMENT We also welcome the opportunity to quote for complete factory clearance B BAMBER ELECTRONICS 5 STATION ROAD LITTLEPORT CAMBS Phone Ely 0353 860185 2483 SURPLUS We offer good prices for test equipment components redundant computers PCB s connectors ment TIMEBASE 94 Alfriston Gardens Sholling Southampton SO2 8FU Telephone 0703 431 323 Immediate settle 1832 used in advertisement Test equipment receivers valves transmitters com ponents cable and electronic scrap and quan tity Prompt service and cash Member of A R R A M amp B RADIO 86 Bishopsgate Street Leeds LS1 4BB 0532 435649 9956 WANTED Test equipment measuring instruments redundant stock manufacturers surplus etc Any quantity large cr one off Please write or phone with details RALFE ELECTRONICS 10 CHAPEL STREET LONDON NW SDN Tel 01 723 8753 2522 Box No Allow two words plus 5 6 Cheques etc payable to IPC Business Press Ltd and cross amp Co Service Quality workmanship by professionals at economic prices Please telephone 01 646 5686 for advice or further details TAMWORTH MANOR 302 310
64. Pins Pence Low profile IC sockets 115 37 4 16 18 20 22 24 28 40 3 14 16 18 22 24 27 38 228 15 Soft sectored floppy discs per 10 in plastic library case 5inch SSSD 17 00 5inch SSDD 19 25 5inch DSDD 21 00 5 inch SSQD 23 95 5 inch DSQD 26 35 1 50 1 60 1 90 2 00 2 20 2 80 74LS series TTL large stocks at low prices with DIY discounts 280 starting at a mix of just 25 pieces Write or phone for list WINDING SERVICE Please add 50p post amp packing to orders under 15 and VAT to total Access amp Visa welcome 24 hr phone service on 054 4221 618 Government amp Educational orders welcome 15 minimum Trade accounts operated phone or write for details HAPPY MEMORIES WW Gladestry Kington Herefordshire HR5 3NY Tel 054 422 618 or 628 2 12 2 44 2 64 0A 450 96 48V Pri 2x 120V Secs 2x 36 48V 36 51 20 P amp P 1 20 2 20 2 40 3 20 3 50 375 Price 537 14 69 17 79 12 0 12 05 3 11 20x2 3x2 338 20 12 0 12 20 9 443 13 1520 2 1Ax2 5 60 1527x2 5x2 483 1527x21A 2 7 30 SPLIT BOBBIN 3VA 15KVA Single amp 3 hase Fast deliveries OROIDALS Wound to order 30VA to 5KVA PLEASE ADD 15 VAT TO ALL ITEMS AFTER P amp P PC or CLAMP 15 amp 3VA Sec V 2x3V 2x4 5V 2x6V 2x7 5V 2x9V 2x12V 2x15V 2x20V 6 9 12 20VA EXPORT ENQUIRIES WELCOMEO Burtord Road Lo 130k 150k 200k 220k 270k 300k P amp P 20p BRIDGE RECT 400V1A 200V 2A 100V 35A 500V 12
65. R G Type 16 ES with a standard tolerance 5 of nominal resistance value All values in Stock 3 watt Series 3 50 per 100 any one value 1 P amp P 4 83 inc V A T 6 watt Series 6 50 per 100 any one value 1 P amp P 8 63inc V A T 10 watt Series 10 50 per any one value 1 P amp P 13 23 inc VAT BRITISH MADE TRANSFORMERS input 240v at 50Hz output 12v 0 12v 1 2 amp with built in ther malovertoad cutout P C mounting 25tor 10 VAT 115for50 VA T 210for 100 V A T 950 for 500 V A T 1 700 for 1 000 V A T Sample sent for 3 75p P amp P 431 inc VAT LESLIE TREMOLO SPEAKER SYSTEM A two speed rotating batfle system which when used as part of an organ hi fi or disco system produces the famous Leslie effect The unit comes complete with a 50 watt 8 ohms speaker at peak output two 220 240v 50Hz motors with centra drive to rotating horn baf fle This gives a three way sound effect i e normal tremolo sound when stationary wraparound sound when revolving at 1rev per sec and supersound at 7 rev per sec Baffle size 485mm x 395mm Overail depth from speaker magnet to central boss of rotating horn batfle 300mm approx 200 for 5 360 for 10 825 for 25 1 500 for50 2 700 for 100 Sample sent for 45 5 P amp P 57 SO inc VAT TWIN KEYBOARD AND FRAME Two 44 note F to C keyboards mounted on a metal frame hinged for easy adjustment Keyboards offset by one octave with keyboard s
66. TO ELECTRONIC SPEECH SYNTHE SIS by N Sclater Price 8 ELECTRONICS FOR HIGHER TECH by S A Knight Price 10 DOMESTIC VIDEO CASSETTE RECORDERS A SERVICING GUIDE by S Beeching Price 15 50 SEMICONDUCTOR DATA BOOK by A M Ball Price 7 50 ALL PRICES INCLUDE POSTAGE THE MODERN BOOK CO BRITAIN S LARGEST STOCKIST of British and American Technical Books 19 21 PRAED STREET LONDON W2 1NP Telephone 01 402 9176 Closed Saturday 1 p m Please allow 14 days for reply or delivery 2245 SATELLITE TELEVISION DISHES 1 2m diameter petal type for home construction from sheet aluminium Suitabie for 4GHz band detailed constructional diagrams and drawings 1 50 including postage to all countries W N Jones 2 Ty n Rhos Gaerwen Anglesey Gwynedd Wales LL60 6HL 2549 VALVES PROJECTOR Lamps 000 types lis 75p world wide export Cox Radio Sussex Ltd The Parade East Wittering Sussex Phone 024 366 2023 1991 WAVEGUIDE Flanges and Dishes Al stan dard sizes and alloys new material only from stock Special sizes to order Call Earth Stations 01 228 7876 22 Howie Street London SWII 4AR 2099 SERVICES Thamescity Limited Electronic Analog and Dwgstall electro pneu matic and comrol systems A amp D facilities for lomg or short run assembly and test to your dengn or ours at our new Maidstone facility 48 Southwark Street London 5 1 1UM Tel 01 407 7441 William
67. Technol 2610 Bris meoo mono oam re oao ian lush 0300 BB16 5 FISI witcne apacitor lecnnology B8103 BFI83 0 wueas0 0 00 mens gaso 7318 0390 aopn M380 0900 ELECTROLYTIC B81058 BFIBA MJES200309 mpn 560 7874 0350 oW D 4 OCUF IV l l 552058 0 Bras 0 MJE2955K0 900 riP20 0430 7995 pas Set eh R N H BC107 BF 94 0 050 TIP12 po d ae Contact us on your needs at Chicago 312 640 acing Sos ono paa MEIA oia fog Bia ERR BC 109 BF196 7713 Boston 617 745 7400 Japan 03 343 4411 ecne nton arias England 0734 788666 Germany 089 928 060 E DASO NP15 0470 mpg 0560 792 DrQ 0 VE TI127 0560 CCB2 13900 0 250 TIP2055 0 340 78 05 ECCa3 NES55 0 TRIPLERS P30540380 78112 ECC83 NESS6 1P1195 iP30550 340 7BLIS ECCAS BYx55 23005e 2250 TiS61 0150 JaL1B ECHBI 350 i590 isa 74124 0 350 ECHB4 BYX55 1881 00 Lm3ogk soon E698 pue 2N 29040 200 LM3I7K 2200 Ecigy 600 2N 29050 200 LM3ITT 1800 Fel gs BYx55 PN 2906 0180 LM323k 4 200 CL86 2N290 0180 LM723 0320 tgo Z BCIQ BF257 8E1411 BF258 BCt42 BF259 BC1A3 BF336 BC147 8337 BCI48 Di BF338 BC149 BF362 BC157 HF422 BLIS9 HF458 BC182 RF489 BC182L Jrx28 BC183 AFXBA 2N 28260 080 T8HGKC 5 700 EFAS 2v 30190 280 7 ros Cs200 Er Semi jn Qn 30630580 78GuIc 1800 Frogs ooooosoocoo tman a a a a 832322322 mjt 883 x 3 E I Ea 3EXB 8 R2008B 0 BOO J96U1C 2 l ECIF STAND 779 I BARE et
68. X HERTZ GOTO 80 read T count Programming the 8255 The function of each port is set up by sending a control word to address 49155 Port A is set as an output and port C as input Remaining ports may be set and used as required Control word format is according to Table 2 The program to initialize the circuit is POKE 49155 137 send control word OKE 49125 DAT send data to d to a converter OKE 49153 read lower port C data Addresses for 8255 control are 49152 for port A 49153 for port B 49154 for port C 49155 for control WIRELESS WORLD MAY 1984 WWW americanradiohistorv com TELEVISION Improving colour television decoding 5 In obtaining improved horizontal resolution consideration must be given to the loss of luminance high frequencies that can occur in the decoder i cs at this stage of signal processing the luminance is clamped blanked and matrixed with the colour difference signals to produce the red green and blue signals for outputs at low impedance The TDA3561A one chip decoder response has a 3dB point at 5MHz but further h f losses occur in the following cir cuitry which provides the red green and blue colour tube drives typically 100V pk pk to the tube cathodes RGB tube drive stage Many home receivers of three or more years old will have single transistor class A video output amplifiers These work well on negative going edges as the load capacitance c r t
69. a leakage and crossta almost complete security against unauthorized interception smaller size and weight lower system cost per channel km In contrast to metal cable sys tems fibre optics is a rapidly deve loping technology It is obvious that fibre optics is currently supe rior in most respects to metal cable transmission techniques these advantages can only be strengthened as the technology matures Over the next ten years or so we are likely to see the increased use of integrated optics in couplers switches modula tors sources and receivers fur ther increasing the advantages of guided optical transmission over metal cable techniques Optical transmitters and receivers are discussed in part 2 of this arti cie WIRELESS WORLD MAY 1984 The report of my death was 9 exaggerated the same can be said of the Sa cem sd still going strong Ba 5 and selling by the million E Au p e E With a range of over 20 different amp families from 400mW to 50W it a is almost certain that there is a e Zener to meet every application amp For your free Short Form guide Cz to these and other Thomson Cc Discrete Products contact us at the address below i i THOMSON CSF alli COMPONENTS THOMSON CSF COMPONENTS AND MATERIALS LTD RINGWAY HOUSE BELL ROAD DANESHILL BASINGSTOKE HANTS RG24 0QG TEL 0256 29155 TELEX 858865 Distributors Abacus Electronics 0635 33311 Blo
70. also has the compiler for the FORTH source code Debugging is inherent in n the FORTH language and once the code is working this can be output toa PROM programmer Use of C MOS throughout has brought the power consumption down to 28mA making the TDS900 especially suitable for portable and battery driven applications VUE UJ THE STREET HEYBRIDGE MALDON ESSEX CM9 NB ENGLAND Tel MALDON 0621 56480 Telex No 95855 Triangle Digital Services Limited 100a Wood Street Walthamstow London E17 3HX Tel 01 520 0442 CIRCLE 014 FOF FURTHER DETAILS CIRCLE 009 FOR FURTHER DETAILS 4 WIRELESS WORLD MAY 1984 WWW americanradiohistorv com Are you as fast as a bullet eee a WOULD YOU HAVE MADE A FIGHTER PILOT NOW YOU CAN FIND OUT WITH THE NEW W REACTION TESTER l A FREE PROJECT FROM GSC amp Split second timing is essential for this the latest and fastest game from GSC Find out how long you could have stayed upstairs before you bought it Press start switch after a random time period a moving light appears The quicker you press the button the longer you stay alive You can t fool this game though a cheat light will tell everyone that you guessed when the lights would come on Speed and concentration are the names of this game build our kit and beat the bullet HOW DO YOU MAKE IT Our FREE project sheet gives you a large clear diagra
71. ancora 12 T ASSO 280 Urcit rce LC2130 350 SL1327 1 10 18 1 20 1 35 You will wonder how your laboratory or workshops 7131 550 L1327Q0 130 TAA700 170 TCA940 165 UPC1181H 1 25 ever coped without LC7137 550 SN76003N 1 95 TBA1208 0 95 TDA440 2 20 UPC1182H 2 95 LM324N 0 45 SN76013N 1 95 TBA120C 1 15 TDA100 1 95 UPC1185H 3 95 amp M380N 0 95 SN76023N 1 95 T8A120T 1 05 TDA1004A 3 25 UPC1191V 1 50 LM383T 2 95 SN76033N 195 TBA120U 1 00 TDA1006A 2 50 UPC1350C 2 95 MS1513L 2 30 SN76110N 0 89 TBA23 1 25 TDAI010 2 15 UPC1353C 2 45 M51515L 2 95 SN76115N 1 25 TBA395 150 TDAI035 2 50 UPC1365C 3 95 j M51521L 1 50 SN76131N 1 30 TBA396 0 75 TDA1037 1 95 UPC2002H 1 95 l M83712 2 00 SN762260N 295 TBA440N 2 55 TDA1170 1 95 555 0 35 MC1307P 1 00 SN76227N 1 05 TBA480Q 1 25 TDA1190 2 15 556 0 42 MC1310P 1 50 SN76533N 1 65 TBAS 0 250 IDA 2700 3 95 723 0 50 EA MC 327 0 95 SN76544N 1 95 T8AS 0Q 250 TDA1327 170 74 0 25 MC1327Q 0 95 SN76570N 1 00 TBAS20 1 10 TDA2002 1 95 747 0 50 e MC1330P 0 76 SN76650N 1 15 TBAS200 1 10 TDA2020 2 45 748 0 35 Y MCI3A9P 1 20 SN76660N 0 80 TBA530 1 10 TDA2030 2 80 7808 0 60 A 9 P MC1350P_0 95 SiK04 795 TBAS30Q 1 10 TDA2522 1 95 Y Me M LA y EN T ete 8D234 0 35 BFR81 025 TIP34B 0 75 R INTERNAL 50 Gt LS SEMICONDUCTORS BD236 0 45 BFR88 030 TIPAIA 045 LCD MULTIMETE LOAD AAY12 025 BC182LB 0 10 8D237 0 40 BFR90 150 TIPAAC 0 45 3 DIGIT 2 150 MHz OSCILLOSCOPE 4 AC127 0 20 BC1
72. and delayed time base Philips PM 3254 Single time base 1145 Philips PM3267 100MHz Oscilloscope 12 50 Versatile and economic instrument designed for advanced electronic environments Separate main and delayed time base controls with comprehensive triggering facilities and trigger view third channel Dual trace 2mV sensitivity full X Y display Z modulation and internal illuminated graticule FOR Philips Fluke Hameg Ice Test Equipment Hameg HM103 10MHz Oscilloscope 158 This small oscilloscope has been designed specifically for field service personnel and advanced electronic hobbyists Single trace 10MHz bandwidth with 2mV sensitivity TV and auto triggering with adjustable level Internal graticule and in built component tester Hameg HM203 4 20MHz Oscilloscope 264 Designed for general purpose applications in industry and education Versatile triggering performance to at least 4OMHz Dual trace X Y operation TV triggering add and invert mode and component tester make the price performance ratio of this Scope most attractive ANEENDAA Hameg HM204 20MHz Oscilloscope 365 High performance scope with peak value triggering up to 50MHz Versatile triggering facilities and variable hold off control Dual trace delayed sweep mode Z modulation X Y operation internal illuminated graticule and component tester complete the attractive specification Hameg HM605 60MHz Oscilloscope 487 Outst
73. best employed in sort haul medium bandwidth systems probably with an inexpensive 0 85um l e d source as modal delay spreading restricts the per formance to around 10MHz km Graded index multimode fibres are the natural choice for long haul high data rate links operat ing up to approximately 15GHz km at 1 3um probably using an i l d source for faster modulation Monomode fibres p at 1 3um with an i 1 d source offer the best performance for ultra high data rates It may not always be possibleto trade off Fabrication control the extremes of the bandwidth distance product because of sys tem power level restrictions imposed by fibre attenuation The only area in which present optical fibre systems are inferior to traditional metal cable systems is in the allowable power budget between the transmitter and receiver It is presently difficult to launch more than several hun dred microwatts of optical power into a fibre from an i l d less for an l e d whereas r f transmit ters can inject many times this level of input power into ordinary copper cables Similarly optical detector receiver arrangements are rather less sensitive 1 to 20nW than r f receivers The allowable power loss between transmitter and receiver inan optical fibre system is there fore restricted to a maximum of around 30 to 40dB for acceptable bit error rates or signal to noise ratios This is much less than a conventional cable system
74. bimorph drive signal is positive negative steps are where head jumps down to skip one track At b tape moves at 80 of forward speed every fourth track Break in electrodes e t played twice using nay Cross wires to give parallel movemen single track reverse jump approx z 010 Bimorph element Slope of bimorph drive 18 negative with positive jumps to repeat one track 1 2 34 5 6 78 9101 1213 161516 17 18 192021 22 23 262526 27 28 29 30 Tope field numbers Thick lines represent fields played 21 Playback field numbers g Te a e le Bimorph drive less dither P i Down 1 track forward jump a 1234567 B 9101712 1314 15 16 12 18 19 2021222320 25 2627 28 9 30 Tape field numbers Thick lines represent fields played twice Eu ee cog EE 46e shop geo og oe 20 AREE Up Bimorph drive Haun less dither os 1 track forward jump WWW americanradiohistorv com qe Fe X qe 0 e rM t VARIABLE SPEED VIDEO Fig 7 Still field mode at a repeats one field endlessly With tape stationary one track reverse jump 1s needed once per field Still frame mode at b repeats two fields endlessly Two track reverse jump once per frame Depending on where tape stops d c component may be needed Fig 8 Single track advance is obtained by normal tape movement Two track jum forwards adds to give X speed two track backwards subtracts to give 1 speed
75. committees When the preferred number system and colour coding were standardized the light current engineers had something of the character of an aristocracy Tenuous links of common education or common experience extended almost everywhere just as we can see the family links in the books of Anthony Powell The two basic factors were the almost universal use of carbon composition resistor and the boom highly seasonable in the manufacture of wireless sets There really were every year new ideas at Olympia and one large manufacturer closed for six months each year because no one bought in the early summer The carbon composition resistor was not very stable so that designers were forced to live with 20 tolerance The method of manufacture had a lot in common with the production of the stodgy school puddings which you can now get only at adecent London club Two buckets of A one of B a shovelful of C and D to taste Blend mould to shape place in a hot oven Sort Sort in fact into bins with 0 8 1 0 1 2 1 2 1 44 1 728 As long as they were inside ceramic tubes the resistance could be printed on the tube Changes of mix to make them fairly damp proof gave a black body which did not need to be encased Like the 1 coin it all made sense to have a set of values and a colour coding system The trouble with answers which make sense is that no one likes them In the 1945 edition of Langford Smith the Radio Manu
76. eprom and freeing the entire 64K byte ram The timing circuit on the reset monostable i c arranges for a much longer time constant to be applied during power up providing a reset pulse long enough to allow start up of all of the system clocks Eprom IC is shown as a 2764 or 27128 but the board may be modified to take 27256 or 27512 devices Prototypes of the computer have been made in wire wrapped and soldered wiring forms the most recent version using Vero 03 2989L boards and wiring pen type 79 1732G Suggested wiring layouts and component place ment diagrams for such boards can be obtained by sending a large s a e to Wireless World s edito rial offices Construction using p c bs is a much easier matter and will be the assumed method When using these boards the i cs should be soldered directly onto the boards with the exception of eproms which should be fitted in good quality sockets Sockets may be used if required but only good quality ones Dynamic rams are best soldered in The natural fear is that of removing i cs should faults occur This is quite easy though either using a de soldering tool or by snipping all of the pins offthe i c body and rem oving them one by one system as complicated as this should not be repaired using the swap and see technique so for those who do not have the test facilities to trace a fault a repair service will be available for systems built on p c bs Standard pitches hav
77. example is dysarthria which results from damage to the central or peri pheral nervous system This may lead to slurring lack of co ordina tion or altered muscle tone which reduce the intelligibility of the speaker s words The effects can range from a slight difficulty in pronouncing certain syllables to complete loss of the power of speech Dysarthria can be a sign of such diseases of the nervous sys tem as Parkinsonism multiple sclerosis and Huntington s cho rea or it may be the result of some incident such as a stroke or head injury The main aim of speech ther apy with dysarthritic patients is to improve the clarity of speech and to minimise the abnormal charac teristics Patients are encouraged to reduce the speed of their speech and to enunciate each syll able separately so that they can articulate with greater precision Unfortunately most find it hard to monitor their own speak ing rate they do not know when they are speaking too fast or that Referente voltage Variable gain amp Microphone amplifier WIRELESS WORLD MAY 1984 ney are eliding words and syl bles Some patients in these groups have spoken rapidly for most of their lives and to change such a deeply ingrained pattern of behaviour may take a sustained effort Many improve their speech dramatically during ther apy sessions only to slip back to their old ways when they return home But with help of a simple tra
78. external modules Personality cards and hardware changes are not required as the machine configures itself for the different devices The EP4000 with 4k x 8 static RAM is still available with EPROM programming and emulation capacity up to 4k x 8 sizes EP8000 8k x 8 Emulator Programmer 695 12 delivery BSC8 Buffered emu lation cable 49 SA27128 Program ming adaptor 69 SA25128 Program ming adaptor 69 EP4000 4k x 8 Emulator Programmer 545 12 de MU VII MALT HRH HN lt u of eux FEATURES W Software personality programming emulation of all EPROMs up to 8k x 8 bytes including 2704 2708 2716 3 2508 2758A 2758B 2516 2716 2532 2732 2732A 68732 0 68732 1 68766 68764 2564 2764 Programs 25128 27128 with adaptors No personality cards characterisers required Use as stand alone programmer slave programmer or EPROM development system Checks for misplaced and reversed insertion and shorts on data lines Memory mapped video output allows full use of powerful editing facilities Built in LED display for field use Powerful editing facilities include Block Byte move insert delete match highlight etc Comprehensive input output RS232C serial port parallel port cassette printer O P DMA Extra 1k x 8 scratchpad RAM for block moving livery 6 BSC4 Buffered emulation cable 39 BP4 TEXAS Bipolar PROM Module 190 Prinz video mo
79. for money deal is the REFUND GUARANTEE if you don t want your GANG OF EIGHT you can return it within a fortnight and we ll send your money back immediately less the cost of postage We realise that this is like operating a free hire service but we believe that most engineers are straight We will be most surprised if we get any GANG OF EIGHTS back FEATURES CONVERSATIONAL LIQUID CRYSTAL DISPLAY NINE INDUSTRY STANDARD TEXTOOL ZIF SOCKETS SWITCH SELECTION OF EPROM TYPE NO MODULES TO BUY PROGRAMS ALL SINGLE RAIL EPROMS INCLUDING 27256 USER CAN CHOOSE NORMAL OR FAST PROGRAMMING ALGORITHM SINGLE KEY OPERATION WORKS FASTER THAN STANDARD PROGRAMMER INTELLIGENT OPERATION TRAPS OPERATOR ERRORS SAFETY FEATURES BUILT IN LOW COST DESIGN GA N G O F EIG HT including instruction card power supply and carriage 395 VAT 454 25 CIRCLE 026 FOR FURTHER DETAILS Lombard House Cornwall Road Dorchester Dorset United Kingdom Telephone Dorchester 0305 68066 Telex 418442 WWW americanradiohistorv com WIRELESS WORLD MAY 1984 AMEN PAUSAID Pausaid This low cost speech training aid won second prize in Wireless World s recent design competition It offers help to a large number of people with moderate speech impairments There are a number of speech disorders which cause patients to lose control of their rhythm of speech or to run words together One relatively common
80. forecast that 40 60 of monplace will not yet be possible A American homes will have cable The Electronic ScientificJour noise cancelling microphone tv by 1980 and at the end of nal was suggested in 19768 pio for display control doubles as 1979 a UK forecast of 100 000 neered with mixed results in voice controlled telephone Prestel sets in 1980 equally split 1979 19829 and is the subject of number selector High quality between domestic and business further experiments today It paperwork is still used and was made seems unlikely that the final form can be transmitted and In 1979 it was anticipated that will replace the scientific and reproduced by the By 1983 all the 220 000 tele social functions of the conven Imagemaster text picture hone subscribers in the Ille et tional journal for many years machine which digitizes illaine department of Brittany It has turned out to be paperwork for storage No will possess desk top video term extremely difficult to design an other devices are needed inals costing 33 each providing electronic device which can access to a local and nationaldat recognise continuous speech abase of telephone numbers from any speaker According to a All these forecasts were wildly classic 1976 article it will be off target many years before this becomes As recently as late 1981 one possible A very large research pundit said that the worldtotalfor effort seems to have produced
81. frequency in the range 250 500 MHz High Q filter 15V DC 854 2 p amp p TYPE 9012 Gasfet preamplifier mains power supply uni 24 50 3 p amp p TYPE 9010 Masthead weatherproof unit 6 50 2 p amp p GASFET MOSFET RF PREAMPLIFIERS Aligned to your specified frequency in the range 30 250 MHz Masthead local use TYPE 9026 N F 1 0 dB Gain 10 40 dB variable 49 50 2 p amp p TYPE 9026FM As above Band II 88 108 MHz 49 50 2 p amp p TYPE 9006 Gasfet N F 0 6 dB Gain 10 40 dB v 65 2 p amp p TYPE 9035 Mains power supply unit for above types 4 50 3 p amp p TYPE 8034 TYPE 8034 PHASE LOCKED SIGNAL SOURCE using low frequency reference crystal Specify output in the range 1 600 MHz Output 10 mW 10 dBm 79 50 2 p amp p TYPE 9113 TELEVISION FREQUENCY CONVERTER Ch of RESEARCH COMMUNICATIONS LTD 45 UNIT 3 DANE JOHN WORKS GORDON ROAD CANTERBURY KENT CT1 3PP SERT TELEPHONE CANTERBURY 0227 56489 CIRCLE 049 FOR FURTHER DETAILS SPECIFICATION HC 6010 DIGITAL 10 Amp AC DC Battery Single 9V PP3 Life zo hrs D imensions 170 x 89 x 338mm n A A Weight 400g inc battery eV t Mode Select Push Button W 910 AC DC Current 200uA to 10A E we 9 95 AC Voltage 200mV to 750V 29 99 xx es DC Voltage 200mV to 1000V Z NP Resistance 20022 to 20M yy Input Impedance 10M0 sw w we ha wt RHR HRM OE Accuracy 0 5 DC Volts 28 RANGES EACH WITH FULL OVERLOAD PROTECTION
82. in compilation distribution sto rage display aesthetics conve nience accessibility and cost has emerged which serves us quite well The new technology has been developed during the last 50 years but 90 of it during the last 15 In that time radio television automation and computers have been followed in quick succession by pocket calculators home com puters online systems word processing machines and video and optical discs backed by a semiconductor technology pro ceeding at an unprecedented speed The general momentum of all WIRELESS WORLD MAY 1984 this encourages the belief that almost anything is possible by the introduction of more technology There is no shortage of e with vested interests to foster this belief However application takes time as has been discussed already Ordinary people get in the way They have contra beliefs generated both by innate conser vatism and in some areas by well founded scepticism This scepticism is in part a reaction to sales razzamatazz to the observed general mismatch between men and machines and to the fact that for every predic tion which turned out to be an underestimate there are several which turn out to be unduly opti mistic or simply wrong Readiness potential and enabling infrastructure Some years ago the phrases Readiness Factors and Enabling Forces were used with reference to teleconferencing The similar phrases Readiness Potential and
83. in the UK The LEVELL TG303 is a function generator together with a frequency counter SINE SQUARE TRIANGLE PULSE amp RAMP 0 02Hz to 2MHz in 7 RANGES EXTERNAL SWEEP OVER 3 DECADES 20Vp p from 50ohm SOURCE VARIABLE DC OFFSET TTLOUTPUT FREQUENCY COUNTER TO 10MHz TG303 CMOS OUTPUT TG303 TG302 135 ex works VAT TG303 195 ex works VAT We supply many other instruments including OSCILLATORS COUNTERS OSCILLOSCOPES dB amp MICROVOLTMETERS Moxon Street Barnet Herts EN5 5S0 England LEVELL ELECTRONICS LTD Telephone 01 4 40 8686 449 5028 CIRCLE 022 FOR FURTHER DETAILS Versatower Arange of telescopic towers in static and mobile models from 7 5 to 36 metres with tilt over facility enabling all maintenance to be at ground level HOME CONTROL CENTRE REMOTE CONTROL KITS FOR A DETAILEO BOOKLET ON FEMOTE CONTROL send 30p 8 x 9 S A E This kit enables you to control up to 16 differ d ent appliances by means of coded pulses in the mains wiring which may be decoded by special receivers anywhere in the house The transmitter may be controlled manually or by the computer MK18 dau Ki 5 interface enabling your favourite micro and MK9 1073 to make your coffee in the morning switch lights any where in the house or your electric blanket in your bedroom Jusu thie rot the MK12 Transmitter Keyboard possibilities and no a MK19 DC Controlled Stereo Ampittier Ki
84. include the Mo such itea atans we do not have it at present wl ELESOF TWARE IE b LAST UPDATED 21 03 84 Magazine o AP vx 2 Transmitted carrier Ww Main O Received 15 data Back BIN es 4 E J Request to send 25 E OB Tear ib send Je O Carrier detect Ui Request fo send i Cur To send Jes 27_ Carrier detect Ring Resef 3 Be LL HSV Wee e X sv Vbb O O AGND Ome 0 D6ND 298217a Tox programs ROM review requires only a set of inverting buffers to drive the line and receive from it However many home computers are not equipped to handle the full set of RS232 signals and external logic may be needed to combine some of them Although the Am7910 has only one transmitter and one receiver Fig 2 separate con nections are provided for the main data channels and the half duplex back channels Thus for Prestel received data appears on the RD pin just as it does in the full duplex modes but data to be transmitted must be applied to separate back channel input BTD instead of the main channel input TD A useful feature provided by WWW americanracdiohistorv com the i c is the facility to operate what might be termed a reverse Prestel mode in other words receiving at 75 baud and trans mitting at 1200 baud This allows the user to communicate with the growing numbe
85. jobs to replace those lost in decaying industries Governmen tal interest in cable systems in the UK is an example The present government takes more of an arm s length view than has formerly been the case in other words it 1s attempt ing to set a climate which it thinks will encourage development rather than becoming directly involved in it hence its action in first liberalizing and then privatiz ing British Telecom in granting licenses for cable franchises and so on Inthe US the trend is simi lar with the de regulation of AT amp T and there are some signs of a move in this direction in con tinental Europe Inevitably governments have been and will continue to be involved in the provision of tele communications through the PTT s a European abbreviation which I shall use to describe all telecom authorities Thus the creation of a suitable PTT see Fig 1 depends upon the actions of s governments The existing national and international PTT telephone network has the great advantage that it exists It 1s far from ideal for data transmission but can be pressed into service for that pur pose Most PTTs have also created or are in the process of creating purpose designed national data networks e have also collaborated under EE auspices in setting up Euronet a network consisting of intercon nected host computers in differ ent countries running databases for information storage and retrieval mainly sci
86. laws Electromagnetic and optical experiments taught the same thing with considerable accuracy But the foundation of electromagnetic theory taught that one particular inertial system must be given preference namely that of the luminiferous aether at rest That aspect of the theory was most unsatisfactory Was there no modification that as in classical mechanics would uphold the equivalence of inertial systems The answer to that question is the Special Theory of Relativity This takes over from the theory of Maxwell Lorentz the assumption of the constancy of the velocity of light in empty space Now it was precisely because the new theory took over the assumption of the constancy of the velocity of light that modern physics became saddled with the three well known mind bending horrors of relativity theory the irrational assumption itself together with the shortening of measuring rods in the direction of travel and the slowing down of clocks due to relative motion which are the inevitable mystical consequences of maintaining that assumption Earlier H A Lorentz had shown somewhat apologetically perhaps that if those particular distortions of physical reality could conceivably occur in Nature then all the inter nal discrepancies of the electrom agnetic theory would disappear He showed further that such dis tortions were necessary if the electromagnetic theory were to be saved In direct and co
87. lecting the dither signal Note the dipulses which are needed to accelerate and decelerate the tracking head during the jump It is possible to stop the tape completely and maintain an out put In this case the bimorph can be made to follow one field con tinually by making a one track reverse jump at the vertical inter val using the drive waveform in Fig 7 a An alternative is repea tedly to Play one frame where a two track jump occurs every two fields as shown in Fig 7 b If the tape is reversed at normal speed the tracking head can still follow the tracks but has to make a two track reverse jump once every revolution From Fig 8 it can be seen that the waveforms needed for 1X and 3 speeds are the inverse of one another This is because the 1 speed is obtained by drum geometry and the 1X and T3X represent an equal depar ture from it This must be looked at in the context of head to tape speed Because the drum peri pheral velocity is the dominant factor stopping or reversing the tape only reduces the head to WIRELESS WORLD MAY 1984 tape speed slightly Similarly doubling or tripling the linear tape speed only slightly increases the head to tape speed Note that in C format the drum turns against tape travel In some formats the drum turns with the tape travel and many of the effects described here will be in the opposite sense When the tape speed exceeds certain limits the bimorph does not h
88. machines 50 00 IVC HI RES IC For Gemini and others please enquire Provides Pseudo high resolution graphics 15 00 DISK PEN C Version 3 Low cost word processor for Gemini and others please enquire Plus large range or overlays for Diskpen HENRYS CP M UTILITIES DISK C 41 Programs for the CP M Systems programmer 57 format 15 00 8 format 17 35 Ask for details on ail of above WHEN ORDERING PLEASE SPECIFY FORMAT REQUIRED Contact Computer Dept if uncertain IC Copyright Cubegate Ltd all rights reserved All above available to retailers and distributors contact Computer Dept for details COMPUTER POWER SUPPLY Switched mode Stabilised Self protecting S C protected etc 220 240V AC 5V 3 34 12V 2 4A 40 cycle 5V 0 5A 12V 0 5A Suitable Apple replacement 50 00 50 00 UK C P 1 50 Galaxy computers with monltors and Disks m NASCOM 2 Available in both kit and built form Featuring Microsoft Basic NAS SYS monitor full QWERTY keyboard of the highest quality 4MHz ZBOA processor lui RS232 1 0 and parallel 1 0 One of the mosi flexible compuler cards around expansion cababilities are impressive using the COMPUTER FANS CU7983 115V 50 60Hz l 12 13W Impedance protected luse 2 in series lor 230V 44 x4X x1 Two for 8 70 UK C P 70p 220 240V as new only 4 78 UK C P 50p each NASBUS and compatible BD BUS expansion cards Expansion includes hi res colour graphics
89. main contention as precisely as I possibly can But first by way of background let me recall how the Special Theory of relativity arose in the first place and what it was intended to achieve Origins of Special Realtivity theory Contrary to received belief the idea of relativity was not a pro duct of the early twentieth cen tury The concept of the relativity of uniform translational motion dates back two hundred years and more before 1905 It is directly associated with the truth of New ton s first law of motion and there is nothing at all complicated about it The following passage appears in Newton s Principia 1687 The motions of bodies included in a given space are the same among themselves whether that space be at rest or moving forward uniformly in a right line without any circular motion A clear proof of which we have from the experiment of the ship wherein all motions happen after the same manner whether the ship be at rest or be carried forward uniformly in a straight line From this quotation it is abun dantly clear that Einstein did not invent the Principle of Relativity He himself in a passage that I shall quote later said so in as many words He had to re state the Principle because for rea sons that we shall uncover shortly his colleagues of those days had been led astray by a chain of false reasoning and had rejected the relativity principle of classical mechanics in favour o
90. manua worth 15 DELIVERY 48Hrs 10 VAT 4000 SERIES HARD DISK DRIVES Data Recording Equipment 4000 Series exchange able IBM type 5440 Disks Units available ex stock and BRAND NEW Please call us or our lowest ever quotation DISK CARTRIDGES X Surplus BASF 12 Secter RKO5 cartridges available small quantity only remaining at 15 each Car riage each 1 50 SWITCHING POWER SUPPLIES The following DC power supplies are available now from stock in limited quantities All fully tested and guaranteed 35V oLD OUT 15 5V amp 20 Amps 20 5V u 40 Amps 5V u 60 Amps 40 19V u 30 Amps 15V 12V amp 5V u 11A 4A and 40A All prices VAT please Carriage 2 each CENTRIFUGAL BLOWERS x TORIN Type U62B1 230V Cap Start supplied very powerful 200W 3 000rpm centrifugal fans for large rack cooling or enclosure extraction appli cations Overall dimensions 20x12 cms outlet 6x4 cms BRAND NEW Surplus stock 15 each inc VAT pp 1 50 ROTRON INSTRUMENT COOLING FANS Supplied in fully tested excellent condi tion as follows 15 30 40 50 5V u 10 Amps 115V 4Yox4Vox1V 5 230V same size 5 50 115V 3x3x1 4 230V 3 size brand new 6 Also small quantity 115V 4 2 size brand new 6 Postage each 50p please KKK KKK Ww10 Repairs and servicing to all equipment at very reasonable rates PLEASE ADD 15 VAT TO ALL PRIC
91. may enable something new to be offered and applied rather quickly If political human acceptability and econ omic factors are favourable the offering will catch on faster an exception to the ten year rule appears The microcomputer is such an exception so its brief history is of some interest The first commer cially available machine to be pro duced in any quality was the Altair 8800 provided as a kit by MITSin 19758 The ingredients which made that possible were develop ments of the transistor first patent filed 1948 improvements 1n photolithography and diffusion techniques enabling transistors and other circuit elements to be manufactured as integrated cir cuits Fairchild 1959 M E Hoff s invention of the Intel 4004 microprocessor containing over 2000 transistors on a chip in 1970 further developed into the 8080 in 1973 US government subsidisation of semiconductor developments amounting to about 1000M in 1958 1974 a large local computer market cap able of absorbing and encourag ing improved circuits For a period the Altair and its successors were limited by small memories and the absence of disc storage to a market composed of enthusiastic hobbyists Software for useful applications was non existent Demand increased with increasing software familiarity better reliability and falling costs but two further related develop ments may be singled out as major contributors to the explo sive dema
92. of Electrical and Electronic Engineering Leeds University Leeds LS29 T 2566 MID WARWICKSHIRE COLLEGE OF FURTHER EDUCATION Faculty of Technology LII IN ELECTRONICS MICROELECTRONICS Applications are invited for the above post for appointment from 1st September 1984 Applicants should possess a relevant degree or professional qualification with some relevant industnal experience and will be required to teach on a range of Technician and Craft courses with particular responsibility for the organisation and development of courses relating to Electronics icroelectronics Application forms and further details may be obtained from the Principal s secretary s a e please Completed application forms to be returned to the Principal within two weeks of the date of this advertisement 2562 FOO II ot PLYMOUTH GENERAL HOSPITAL DEPARTMENT OF MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING Applications are invited for two posts at Greenbank Hospital Post A Technician end Post B Technician mechanical The person appointed to Post A will be a member of a team of eleven in a well equipped and expanding unit offering support services in the various aspectsof the management of clinical electronic equipment in hospitals and health centres throughout the Plymouth Health District The person appointed to Post B will be a member of a team of five in a well equipped and expanding unit dealing with the maintenance and dev
93. part in controlling the buffering of the data bus Z80 control signals and virtu ally all others in this design are active low i e they assert their Meme LL Ram address lines t Data outpu Data valid 38 Agrefresh function by going to the negative or 0 state Fhe normal dnb tion of a gate function is based upon positive logic so that for instance a 74LS02 is deemed to contain four two input NOR gates In this circuit diagram and following ones gates are shown in their logical context This can be seen in the 74LS02 which arbi trates the data bus buffer direc tion IC Here three of the four gates have been drawn in their inverse form i e as AND gates with active low inputs rather than as OR gates with an active low output Having differ ently shaped gates in the same i c takes some getting used to but it helps understanding of the logic For example in the case of 1C direction line IN becomes active when M1 and IORQ or RD and not MREQ and not MEMDIS are active Translated into English this means that the data buffer faces towards the Z80 during interrupt acknowledges and during any read other than oneon the processor board mem ory Control gating for the bus buf fer is fairly complex as the buffer has to respond to various condi tions summarized in Table 2 One reason for such a tight defini tion of the bus operation arises from the use of mode 2 inter
94. produce a silicon chlorine gas thus etching away at the surface This process will enable Toshiba to reduce the number of pattern forming steps from seven to one and ensure that damage caused by the etching and pattern forming process itself is eliminated WWW americanradiohistorv com Toshiba expects that when the process becomes operational within a few years it will make possible a major advance in precision processing of wafers and will have a great influence on the production of extremely large scale integration a 16M bit memory has been mentioned Fine line engraving of 0 5 microns or below would become possible without the inherent danger of damage to the circuits caused by reactive ion etching The expensive production equipment needed for resist coating developing and resist removal in clean room conditions would all be eliminated Part of a gallium arsenide microcircuit for microwave applications showing integrated inductors with bridge connections Because of the particular suitability of GaAs i cs for microwave circuits including satellite communications Plessey who supplied the picture are to mass produce such circuits Up to now they have only been made in small batches 200HM NEWS Software course forteachers The second pack in the Open University s Micros in Schools project is a training program for teachers which discusses software design and helps them to select the best
95. produced Phloopy which uses a continuous loop oftape about three meters long in an interchangeable cartridge Tape speed is 15in s and 0 25in instrumentation tape is used Each cartridge offers a capacity of 100Kbytes and a transfer rate of 10Kbytes s typically a file can be found and loaded in three or four seconds The special secret of Phloopy is that it records bytes in parallel by using a nine track head The controller includes an on board microprocessor which incorporates error correction facilities and can take over many of the housekeeping and file handling tasks of the computer The system has been designed for the BBC computer although other versions are on the way and costs 99 plus 25 for an interface module which can handle up to eight drives Phi Mag Systems Ltd Tregonnie Industrial Estate Falmouth Cornwall TR11 4RY WW 215 a a EG SSS eee i SS SES WWW americanracdiohistorv com WIRELESS WORLD MAY 1984 If you need assistance in HiFi audio service Here s all the help you need Philips versatile PM5109 LF generator and unique combined distortion meter oscillator the PM 6309 give you all the help you need for HiFi and audio service applications They re easy to operate and economically priced PM5109 brings together all the high technology features you require from a test instrument It offers symmetrical or asymmetrical outputs pure sine wave signals a wide 10 Hz
96. s k signals into TEST PATTERN Two new colour bar and pattern generators have been announced by Advid The Unachm EP690 is a bench insturment intended for use by broadcasting stations close circuit studios laboratories production test and service departments It can produce colour bars cross hatch chequer board staircase and other patterns all of which are available as composite video or r f modualted signals The signals may be output in a frequency range from 35 to 950 MHz It costs 495 The second instrument Type GC981 is a small hand held device for use by the service engineer in the field It gives ten test patterns and colour bars asa modulated r f output in the the mains supply Each receiver has a frequency comparison decoder The frequency band used is 110 to 125kHz which is suitable for continuous transmission Each Datapath installation uses one central frequency and all 256 remote switches are controlled from a single channel Accuracy is ensured by including a redundant data byte at the end of each message this is used as a check byte and prevents interruption or interference from any other source The checking procedure introduces a delay which can be up to two seconds for switch on or up to 30 seconds to switch off To prevent interference with neighbours the signalis only 10mW which range 47 to 65MHz 175to 217 MHz and 470 to 860MHz It comes complete with leather case NiCd batter
97. signals will be incorporated AlthoughJapan has supplied the world with c b equipment it is one of the last major countries to introduce c b Mobile rallies to be held during May include an Anglo Scottish rally at Kelso on May 6 Swindon Oakfield School and Otlev Flower Show Hall Harrogate on May 13 Drayton Manor Park near Tamworth on May 20 and East Suffolk Wireless Revival Suffolk Showground Ipswich on May 27 Inthe period to May 1984 the Radio Amateur Licensing Unit of the Post Office is sending a questionnaire to each licensed radio amateur in the UK However the main purpose appears to be to check postal addresses and post codes Solar flux levels were unexpectedly high during February 1984 reaching the highest levels since December 1982 The RSGB have extended the deadline for the additional 50 MHz permits to April 30 at the request of the DTI PAT HAWKER G3VA WIRELESS WORLD MAY 1984 PREFERRED HISTORIES Mr Scott in theJanuary issue has drawn quite the wrong conclusion for his final quotation and his conclusion reflects his thinking throughout The modern camel has been designed by a large committee of users whose lives and livelihood have depended on their transport Camels work for them as horses work for Mr Scott and Jorrocks Horses one may recall did not work for Captain Scott The appropriate quotation might be Belloc Only an aristocracy can be governed by
98. speed laser stroboscope for magnetic bubble research Hobbies include walking cycling climbing motorcycling films literature and photography References l T Li Advances in optical fibre communications an historical per spective IEEE Journal on selected areas in communications vol SAC 1 no 3 1983 pp 356 72 2 H F Wolf Handbook of fibre optics chapter 2 Granada London 1979 3 S D Personick Review of funda mentals of optical fibre systems IEEE Journal on selected areas in communications vol SAC 1 no 3 1983 pp 373 80 4 J W Fleming and V R Raju Low loss single mode fibres pre pared by plasma enhanced MCVD Electronics Letters vol 17 Nov 1981 pp 867 8 5 D N Payne and W A Gambling Zero material dispersion in optical fibres Electronics Letters vol 11 April 1975 pp 176 8 6 J R Stauffer FT3C a light wave system for metropolitan and intercity applications IEEE Journal on selected areas in communications vol SAC 1 no 3 1983 pp 413 9 44 OPTICAL FIBRES Table 1 Principal limitations on fibre optic systems MULTIMODE FIBRE OPTICAL SOURCE Step index Gradedindex l e d 10 Z 15 A0 85um MHzkm_ GHzkm 6A50nm lt 500 Z 500 7 Mhzkm MHzkm 3dB km 3dB km Led 10 Z 15 Z A1 3u MHzkm GHzkm 6A2nm 428 28 GHzkm GHzkm 1dB km 1dB km id 10 p A0 85 um MHzkm GHzkm 6A2nm 25 25 BHzkm GHzkm 3dB km 3dB km i l d 10
99. tag NE AMI BC212L 0 BFYS1 SAS560 1100 amp C213 BFY52 Sanao 19 2N 34400 560 m I RES HALL A UPPER I eau prr EIE Sene dd 50p P amp P Du 15 G Coll BC214L BRY64 5876023N1400 ease a p an at 15 Govt Colleges etc 8237 BR 100 5N75033N1 80 ders accepted l Ere HOM ERE Guotendns given for Large Quantities BC30t BSX21 5N762260 900 Please allow 7 days for delivery l amp i BC302 BSx26 SN75227 0 800 All brand new Components All valves are new and boxed 9 N 3C303 35x29 Ring for items not listed We stock 3 000 items I EO KENS l STET IE UT pem mum ue GRANDATALTD i 34 35 MARKET PLACE WOKINGHAM BERKSHIRE RG11 2PP I PES Suita MA Usa a50 Weer MDC EE ERE 1 4 L H l Telephone Wokingham 0734 788666 Telex 847510 EGGUK J Ed gue e 600 Telephone 01 904 2093 amp 904 1115 6 ee MEM END EEG GENE RD MAR EDD GEO NES eee GEO GA Bye CE Telex 932885 Sunmit CIRCLE 057 FOR FURTHER DETAILS CIRCLE 043 FOR FURTHER DETAILS 16 WIRELESS WORLD MAY 1984 WWW americanradiohistorv com NEW from Kontakt The capability and effect of compressed air in a handy can JENS ON 67 efficiently removes dust and deposits from electronic components set electronic and electrical appara tor tus Microscopes medical equipment cabinets etc Abso 6 lutely no spray residues No compressed airline needed peor With plug in nozzle even blows S around corners Ready for use Em in the service kit Kontakt 60 Dissolves oxides and sulphides re moves dirt
100. there must be a mistake some where There is and we can loc ate it easily by transferring co ordinates and joining observer M in his moving train as we are entitled to do by the Principle of Relativity forgotten it The situation is as shown in Figure 3 The distances AM and BM are equal as also are AM and BM because Einstein has chosen to make them so The lightning flashes are simultaneous by Einstein s own definition in that the light signals emitted from them travelled the equal distance AM BM at velocity c and there fore reached the fixed observer Mat the same instant According to his own second postulate the motions of the sources A and B relative to M are irrelevant each light signal travels towards M at the same universal velocity c Therefore since AM is equal to BM so long as the Relativist does not change the rules these signals must arrive at M at the same time that is simultane ously the quotation above Einstein was actually arguing that M was hastening towards the light from B relative velocity c v and riding ahead of the light from A relative velocity c v so that their times of arrival at M must differ But even the Master may not be allowed to keep his cake and eat it According to his The incidence of future position in this context is not unique to this scenario It arises whenever one tries to measure the position of a moving bod
101. to a fibre bandwidth length product of WIRELESS WORLD MAY 1984 approximately 1 to 5GHz km at 0 85um due to modal delay Hd for a graded index fibre a substantial increase The penalty is the extra manufactur ing difficulty of retaining tight control over the index profile for even slight unplanned deviations in the index profile will cause a disproportionate reduction in the bandwidth length product An alternative way to reduce the modal delay spread is to make the fibre core region much nar rower than the multimode fibre core but still with a step index Fig 2 c Asthe core diameter is reduced toward the wavelength of light fewer and fewer of the higher order zig zag modes can propagate and the tibre eventu ally becomes a monomode wave guide HE mode when the core diameter falls below approxi mately three times the wave length of the optical radiation It is extremely difficult to make fibres with such a narrow diame ter 2 to 3um and so usually diameters in the range 5 to 10um are used and a few low order propagation modes tolerated In contrast a typical multimode step index 50pm fibre may sup port several thousand porpaga tion modes The modal delay spreading of a true monomode fibre must be zero but there are usually several low order modes present ina practical fibre making it diffi cult to give meaningful figures For a step index monomode fibre modal delay spreading is not usually the restr
102. to your order All prices correct at Addes time of going to press VISA Telephorie o MEN o CIRCLE 020 FOR FURTHER DETAILS 10 i TYPE 9051 TYPE 9046 VMOS WIDEBAND LINEAR POWER AMPLIFIERS 4 watts RF output Without tuning Power gain 10 dB 24V supply TYPE 9046 100 KHz 100 MHz 84 50 3 50 p amp p TYPE 9051 20 MHz 200 MHz 84 50 3 50 p amp p uuu gate v E E SEE de TYPE9152 TELEVISION LINEAR POWER AMPLIFIERS Tuned to your specified channels in bands IV or V TYPE 9061 150 mV input 10 mW output 120 5p amp p TYPE 9152 10 mW input 500 mW output 160 5 p amp p TYPE 9159 500 mW input 5 watts output 180 5 p amp p VMOS LINEAR POWER AMPLIFIERS Tuned to your specified frequency in the range 10 250 MHz TYPE 9155 3 Watts input 30 watts output 240 10 p amp p TYPE 9165 As above with integral mains power supply unit 320 15 p amp p TYPE 9086 FM TRANSMITTER 88 108 MHz 50 watts RF output 24V supply Complete modular system 380 20 p amp p TYPE 9087 As above with integral mains power supply uni 460 25 p amp p TWO STAGE GASFET STRIPLINE PREAMPLIFIERS Tuned to your specified channels in bands IV or V TYPE 9002 Two stage Gasfet preamplifier N F 0 7 dB Gain 25 dB High Q filter 15V DC 85 2 p amp p TYPE 9004 UHF two stage Gasfet preamplifier N F 0 6 dB Gain 25 dB Aligned to your specified
103. training and acceptance facilities EUROPEAN SERVICE ENGINEER Ret RE2 Interactive Video Computer Products Salary Negotiable Based Reading Plus Car An adaptable and self motivated person is required to provide service support and practical training on the above display systems at our distributors and customers premises in the UK Europe and certain other countries Formal qualifications in electronics are required and service experience on video displays and some knowledge of personal computers or microprocessor based equipment would bea distinct advantage as would a foreign language TEST SERVICE TECHNICIAN Ref RE3 interactive Video Computer Products Salary Negotiable Based Reading Plus Car An interesting position is offered which will involve carrying out regular quality control checks on pre manufactured Interact systems passing through our Reading distribution and service depot The post will also invoive service and update of display units returned from the field and the preparation of fault investigation reports Formal qualifications in electronics would be an advantage Asmall amount of UK and overseas travel may also be required We offer an attractive remuneration package with competitive salaries and company profit sharing scheme All replies will be dealt with in the strictest confidence Write for an Application Form quoting the position reference number to Mr J F Cowan Pe
104. whole science has like Topsy in Uncle Tom s Cabin just growed Well what of it one might ask it works well enough doesn t it Get yourself a circuit diagram of your own receiver study it and then ask yourself how you would like to track down an obscure fault in the heart of it Logical step by step fault tracing is not so easy The point J wish to make is that it has all developed out of pre war neon relaxation oscillator technology If there had never been any television prior to 1980 say then we would not have started from there and we would not still be perpetuating that piece of non ideal practice At present I believe the following line standards exist 405 525 625 819 929 and the Japanese are developing 1251 lines The advent of satellite television broadcasting gives the world a chance to make a clean break with the past and to adopt anew elegant and simple global standard For a start lack of bandwidth need surely no longer compromise and complicate system design For instance one could have three separate colour carriers thus greatly simplifying everything Since all receivers are likely to incorporate at least one frequency crystal there is no need to transmit line as well as frame synchronizing pulses Interlacing could probably be dropped in favour of some round number of lines e g 1200 1500 1800 2400 or 3000 and the sooner the shadow mask goes the better Modern tv receivers
105. 0 0 25 BA145 0 3 BC22 9 1 BDISI 1 20 BFS98 0 20 MJE2955 1 30 X29 2 00 TIC226D 1 20 1N4005 0 09 2N2223 445 PN4060 016 0 25 BAI48 015 BC2 9 1 BDi83 0 80 BFWIO 0 97 MJE3OSS 1 10 OC35 1 50 TIL209 0 16 IN4006 on 2N2368 0 25 2N4061 0 16 0 25 BAIS4 0 10 BC214 9 11 BD2137 0 54 BFW1 0 96 MPF102 0 5 OC36 1 50 TIP29 0 43 iN4007 0 12 2N2369A 0 25 2N1062 0 16 0 30 BAISS 9 11 BC237 9 11 BD238 0 54 BFX84 0 30 MPF103 0 35 OC41 0 90 TIP30A 0 45 IN4009 0 07 2N2484 0 25 INI 0146 ACISI 0 28 BAISe 0 10 BC238 9 1 ppxio 091 BFX85 0 30 MPFIO4 035 OC42 0 90 TIP3IA 0 33 IN4148 0 04 2N2646 0 50 5N426 016 ACIMIK 0 35 BAW62 0 05 BC30 033 BDX32 2 00 BFX87 0 30 MPFI05 035 OC43 1 50 TIP32A 0 36 INS400 0 13 2N2904 0 32 IN4286 0 15 ACI2 0 28 BAXI3 0 06 BC303 034 BDY20 1 50 BFX88 0 30 MPSA06 0 26 OC44 0 85 TIP33A 0 54 INS40 0 13 2N2905 0 32 2N4288 0 18 ACIK 0 35 BAX16 0 06 BC307 9 11 BDveo 275 BFYSO 025 MPSAS6 0 028 OCAS 0 65 TIPMA 0 67 IS44 0 04 2N2906 0 1 2N4289 0 18 AC176 0 30 BC107 0 16 BC308 9 1 BEUS 0 35 BFYS 0 25 MPSLOI 0 53 OC7I 0 55 TIP4lA 0 44 15920 0 08 2N299 0 21 INHO 0M AC187 0 28 BC108 0 16 BC327 9 5 BFI52 0 16 BFYS2 0 25 MPSLO6 0 65 OC72 1 00 TIP42A 0 42 18921 0 09 2N2924 0 26 2N4401 LL ACI88 0 28 BC109 0 16 BC328 0 12 F153 016 BFY64 0 0 MPSUS6 0 69 OC 1 00 TIP955
106. 0 12x3 220 250V 60mA BV 2A 5 00 1 BAKER PORTABLE DISCO 150 w 7 att Twin console amplifier PE eRe ee re MR Step Down 115V to 240V 150W 9 250W 12 500W 14 2 muke and headphones twin speakers 330 300 watt 399 Carr OX p 8x p 14x p 10x 15 30 Console decks pre amp 105 Carr 12 12 x 8 130 16 x 6 1 30 14 x 9 1 75 12 x 12 1 80 16 x 10 2 10 GENERAL PURPOSE LOW VOLTAGE Price Post PA CABINET SPEAKERS Complete 8 ohm 60 watt 17x 15x9in ALUMINIUM BOXES 4x4x 1 1 20 4x212x2 1 20 3x 2x 1 1 20 Zam ga Soe ERE UM eo fon 1 21 Post 4 4 or 8 or 16 ohm s watt 23x in 52 90 watt p amp 6 8 E i 5 e b i i id D x E epidemia 2amp 6 8 10 12 16 18 20 24 30 36 40 48 60 10 50 2 32x 15x Tin 71 150 watt 80 Carr 10 Black vinyl covered X 30 9 x 4 x A 3 3 amp 6 8 t0 12 16 18 20 24 30 36 40 48 60 12 50 2 POTENTIOMETERS 5k 2meg LOG or LIN L S 50p DP 90p Stereo L S 5 8 10 16V 2amp 2 50 1 0 8 12V 5 amp 5 00 1 BAKER LOUDSPEAKERS Post 2 each 1 10 OP 1 30 Edge Pot 5L SP 45p av 12 amp 2 00 1 15 0 15V 1amp EJOO MODEL INCHES OHMS WATTS TYPE PRICE A EAE amp 350 1 15 0 15V 2amp 5 00 1 DG 50 10 10 8 16 50 PA 18 ma 50 1 20V1 4 00 1 MINI MULTI TESTER 7 50 Post 50p 9V 3amp 400 1 20 0 20V 1 amp 3 50 1 MIORANGE 10 8 100 MID 25 Pocket size moving coil instrument 4000 o p v 11 9 0 9V 50ma 150 1 0 12 27V 2am
107. 0 MARCONISIGGENTF2012 400 520MHz FM 350 MARCONI MOD METER TF2300S 2 1000MHz AM FM 375 S E LABSSTROBESMB 125 RACAL AIRMEC SIG GEN 365A 1 320MHz AM FM 325 B amp KTAPE RECORDER type 7001 600 H P SHF SIG GEN 620A 7 11GHz 225 H P CALORIMETRIC POWER METER 434A DC 12 4GHz 10mW 10W 250 H P RF MILLIVOLTMETER 411A 500KHz 1 GHz 10mV 10V 150 MARCONI DIFF OC VOLTMETERTF26060 1100V 275 GRFREQ METER amp DISCRIMINATOR 1142 A 200 CLAUDE LYONS VOLTAGE STABTS2 AC240V 12A 100 KINGSHILL STAB POWER SUPPLY 500 Metered 0 60V 0 0 5A P amp P 4 40 EXECUTIVE TELEPHONES PUSH BUTTON ns including 10 1allin 25 each P amp P 4 SAMPLE OF STOCK SAE or IBlephene for LISTS Please check availabilty betore ordering Carriage all units 7 VAT to be added to total of Goods and Carriage STEWART OF READING 110 WYKEHAM ROAD READING BERKS RG6 1PL X Telephone 0734 68041 Callers welcome 9 a m to 5 30 p m Monday to Saturday inclusive CIRCLE 063 FOR FURTHER DETAILS LEARNING MICROPROCESSOR USING MICROPROCESSOR GET THE LS LS series of microprocessor learning systems offers inexpensive trainers in learning and practising microprocessor programming and interfacing low cost controllers in automauon and OEM The series comprises systems based on the most popular 8 bit microprocessors 6502 6802 6809 Z80 and 8085 Features 20 editing debugging commands in EPROM 3 16 user keys Hex keys 2 K RAM 1
108. 0 00 Pt3134A 1 0 01214 870 28C535 0 38 2sc1678 125 BLX93A 36 00 PT31348 275 S012 16 11 009 28C535A 0 38 2SC 1729 18 00 B x98 132 00 PT3134C 12 00 501219 18 00 2SC5358 0 38 25C 1730 025 BLv87C 7 50 PT31340 12 50 5012194 18 00 25C535C 0 35 28C17400 0 20 BL vaaC 11 00 PT3134 30 00 501220 9 50 2SC540 2495 2SC1765 7 75 nr Y88CF 11 00 PT31614 75 S01222 5 11 00 2SC608 075 2sc amp isv 0 28 BLv89C 1300 PT316 8 75 01222StuD 1100 2sc6a4 0 25 28c1906 0 33 BL v90 4500 PT31 61C 8 50 S01224 2 13 00 25C68a O 28 25c1907 30 BLYSICF 11 00 PT31610 14 00 501229 F1 10 95 28C703 36 00 25c19 5 210 BL v94 45 00 P13161F 3000 SD 229 STUO 1095 2SC7 0 O 45 25C1946 19 75 MRF208 12 00 Pr3503 695 S012446 1275 2 C7100 28 25C1946A 16 50 MRF212 12 00 PTa261A 16 00 501256 6 95 25C7 50 O 40 25C 19 7 9 88 MAF221 12 05 Pra2618 24 00 SD1262 15 00 2SC SE 0 40 28 1955 7 20 MAF229 3 50 PT4261C 0 00 1270 375 2SC717P 0 38 28C1966 1 00 MRF231 12 36 Pr4316C 12 00 S0 272 1095 2SC730 1 10 25C1967 5 00 MRF232 13 50 PT43160 18 00 501272 2 1095 2sc73 3 95 25C1968 7 50 MAF233 14 30 PT4316E 25 00 501278 1375 28C732 0 25 25C1968A 22 00 MRF234 16 00 PTA316F 30 00 501278 1375 25C741 2 50 25C1969 1 50 MRF237 2 10 PT566 C 14 00 SD 285 1275 2SCB82 6 60 28 1970 5D MRF238 12 60 P1875 23 00 01300 125 25C8288 0 30 25C 1971 3 00 MRF239 20 00 PT8820
109. 0 29 2SC1678 125 s 8C140 0 31 BD115 030 BF200 0 40 MPSAS2 0 30 2SC1909 195 VERSATILE Delivers more than 1kW into 72to 8 ohms BC141 025 BD116 060 BF241 0 15 MRF450A 12 50 2SC1945 2 65 OR 2 x 600W into 2 to 80 BCA 021 BD124P 0 59 BF245 A 030 MRF453 17 50 2561963 0 95 x i i BC143 0 24 BD131 0 32 BF256 LC 0 28 MRF454 23 50 2SC1957 0 80 OR4 peg 2to 2 200W into 80 BC147 0 09 8D132 035 BF257 0 28 MRF475 250 2SC1969 1 95 x into 2 to 8 8C 47B 0 09 BD133 040 8F258 0 28 MRF477 10 00 2SC2028 1 15 OR 1 x 300W into 2 to 40 BC148A 0 09 BD135 030 BF259 0 28 0C23 1 50 2SC2029 1 95 1 X 150W into 4 to 80 8C 48B 0 09 BDI36 030 BF27 026 OC42 0 55 2SC2078 1 45 BC149 0 09 80137 0 32 BF273 0 13 OC44 0 75 2SC2091 0 85 Etc etc BC157 012 80138 0 30 Bf336 0 34 OC4S 055 2SC2098 2 50 Y z 8C158 0 09 BD139 0 32 8f337 0 29 OC70 0 45 2SC2166 1 95 Having been closely involved in a wide variety of OEM applications of their amp BC159 0 09 BD140 0 30 BF338 0 32 oc71 0 55 2SC23 4 0 80 boards Pantechnic became aware of numerous implementation problems often BIET Me BD144 110 ERE 0 37 OC81 0 50 PEE Que left untackled by other amp board manufacturers These problems specifically of 161 BD159 0 65 62 0 38 R20088 1 70 size and thermal efficiency became particularly aggravated at high powers and pele EIE eps Hs EE 30 RI ae Se 170 considerably lengthened OEM product development time BC171A 0 10 8D179 072 BF394 019 R2323 0 66 35K88 0
110. 0 30 BYIOO 0 40 OAB 0 17 OCO3 2 00 ZTX30 0 13 2N1131 0 30 2N3704 0 1 25324 3 50 AF115 075 BCH7 042 BCY58 0 19 Brig 02s BYI26 0 13 OA85 017 OCI39 3 00 ZTX30 0 14 2N1132 0 0 2N3705 0M 25701 2 00 AFII6 075 BCMS 0 12 BCY70 0 37 BFig4 028 BYI2 0 14 OA90 0 08 OCHO 4 0 ZTX302 0 18 2N1302 1 20 2N3706 0 1 ISIA 0 95 AF117 0 75 BC149 013 BCY71 0 18 BF185 9 30 BZX61 0 17 OA91 0 08 OCI4I 4 25 ZTX303 0 18 2N1303 0 80 2N307 0 11 25746A 0 95 AF139 0 3 BC157 013 BCY7 0 17 Brigg 0 14 Series OA95 0 08 OCI70 125 ZTX304 0 20 2N1304 1 20 2N3708 0 10 i AF186 1 00 BC158 013 BCZII 175 BF195 0 2 BZY88 0 10 OA200 015 OCI7I 125 ZTX311 0 2N1305 1 00 2N3709 0 11 AF239 0 39 BC159 0 13 BD15 0 42 BF196 0 13 Series OA202 015 OC200 1 50 ZTX34 025 2N130 50 2N3710 0 10 CV Devices AFZ11 4 00 BC167 0 11 BD121 170 BFIS7 0 14 CRSI40 0 60 OA2I 1 50 OC201 2 50 ZTX500 0 14 2N1307 1 10 2N3711 010 Large stocks AFZ12 4 400 BC170 0 1 BDI23 280 BF200 0 40 CRS340 0 75 OAZ200 1 50 OC202 2 75 ZTXSO1 0 14 2NI308 175 2N3771 i40 Prices on ASY26 140 BCI71 0 11 BD124 2400 ppp 0 25 CRS360 0 90 OAZ201 1 50 OC203 3 00 ZTXSO2 0 18 2N1309 120 2N3772 1 60 application ASY27 0 90 BC172 0 11 BDI31 0 44 BF244 0 28 GEX66 3 00 OAZ206 1 50 OC204 3 00 ZTX503 0 19 2N1613 0 32 2N3773 1
111. 0 70 2G301 400 2N2925 022 N4022 01H ACYI 130 BC113 0 15 BC337 0 32 prisa 9 17 BFY90 0 95 NES5S 045 OCA 0 70 T P3055 0 56 2G302 1 00 2N2926 0 15 2NSA4S7 02 ACY18 L15 BCII4 0 15 BC338 9 2 BFIS9 0 17 BSX19 0 27 NKT401 X50 OC7S 0 65 TIS43 0 43 26306 1 00 2N3053 026 INS458 032 ACYI9 L10 BCHIS 0 8 BCY30 125 BFi o 0 47 BSX20 027 NKT403 2 50 OC76 100 ZS140 025 2N404 1 30 2N3084 0 55 3Ns4s9 02 ACY20 1 0 BCll6 019 BCY31 1 50 BFi67 0 24 BSX21 029 NKT404 220 OC77 100 ZS170 0 1 2Ne96 0 32 2N3055 0 65 3801 10 00 ACY2 1 15 BC117 0 23 BCY32 150 BF173 0 30 BT106 120 OAS 120 OC8I 0 65 ZSI78 0 54 2N697 0 32 2N3440 0 70 S019 12 00 ACY39 2 50 BCIIS 0 18 BCY33 1 10 BF177 0 35 BTY79 400R OAT 0 60 OC8IZ 1 20 ZS271 0 23 2N698 9 32 IN3441 0 85 25026 25 00 ADI9 075 BC125 018 BCY3 100 ppi78 0 35 2 00 OA10 0 55 OC82 0 90 ZS278 0 57 2N705 125 2N342 125 28103 150 ADI61 0 35 BC126 0 18 BCY39 3 40 BFI79 0 35 BU205 130 OA4 0 12 OC83 1 00 ZTXI0 0 12 2N706 0 25 2N3614 10 28302 2 00 ADI62 0 35 BC135 0 15 BCY40 2 80 BF180 0 28 BU206 1 0 OA70 0 25 OC84 0 80 ZTX OS 0 12 2N708 0 25 2N3702 Oll 58303 1 50 AFI06 0 35 BC136 0 19 BCY42 0 30 Brigy 0 28 BU208 2100 OA79 0 12 OCI22 275 ZTXIO9 0 12 2N930 0 25 2N3703 01l 25322 3550 AFI4 075 BCI3 019 BCY43 020 BFig2
112. 00 each Remote Control Price 72 00 each Reflectometers type R F L 1A made by Telecommu nication Ltd freq 68 174 Mh 50 ohms impedence Price 75 00 each Prices shown do not include VAT Large quantity of spare parts for Pye Linear Amplifier A200 Pye Otimpic type M202 Pye 1000T SSB Pye Tx Type T1000 FM VHF Pye W15 FM Pye TX Type R17 R18 VHF FM Pye SSB 130M amp F COLOMOR ELECTRONICS LTD 170 Goldhawk Rd LondonW12 Tel 01 743 0899 or 01 749 3934 0pen Monday to Friday 9 a m 5 30 p m CIRCLE 006 FOR FURTHER DETAILS WWW americanradiohistorv com 137 Standard Ranges in a variety of sizes and stylings available for 10 14 days delivery Other Ranges and special scales can be made to order Full Information from 138 GRAY S INN ROAD W C 1 METER PROBLEMS g HARRIS ELECTRONICS London Phone 01 837 7937 Telex 892301 CIRCLE 069 FOR FURTHER DETAILS STEREO MICROPHONE AMPLIFIER 50 or 200 Ohm balanced microphones to balanced lines Variety of low frequency characteristics for im proving the clarity of recordings Inputs filtered against radio interference Complete boxed unit or double mumetal screened amplifier module alone APRS STAND 133 Surrey Electronics Ltd The Forge Lucks Green Cranleigh Surrey GU6 7BG England Tel 0483 275997 WIRELESS WORLD MAY 1984 M MPa QE or Electronic Brokers
113. 05 16A 400V 110p 741514 60p 74LS164 30p 745194 300p 4538 90P 15V 100mA 78L15 30p 79L15 50P BC109C 20p BFY90 930p TIPAIA 50p 2N3704 5 16p Ga90 91 9p 16A500V 130p 74153 60p 74L5165A 120p 748195 300p 4539 930p OTHER BCI69C 16P BRY39 45p Tiaic 55p 2N3706 7 16p OA95 ab T2800D 130p 74154 200p 74LS166A 120p 749196 300p 4541 S0p aS aa BC172 J8p BSX19 20 30p TIP42A 60p 2N3708 16p OA200 gp TIC2060 60p 74155 60p 74 5168 140p 745200 450p 4543 100p REGULATORS 8C177 8 30p BU104 225p TIPA2C 65p 2N3773 200p OA202 10p T C2260 75p 74156 60p 7418169 140p 74920 320p 4551 250P M309K iA sv 140p78PO5 900p BC 79 30p BU105 190p TiPS 160p 2N3819 40p 1N914 4p TIC 246D 110p 74157 60p 74 5170 120p 745225 650p 4553 220p TM317K T03 250p78H32 850p B8C182 3 15p BU108 250p TIP55 180p 2N3823 30p 7b 74159 180p 74LS173A 120p 749240 250p 4555 0p 143171 100p 7BHGKC 600p BC184 JeP BU109 225p TIP120 75p 2N3866 _90p 1N4148 4b THYRISTORS 74160 90p 74LS174 75p 74924 300p 4556 70P w337T 225p 78HOSKC 650p BC187 30p BU126 150p TIP121 75p 2N3902 700p 1N4001 2 5p 74161 75p 74LS175 75p 749244 400p 4557 250P w353k 3A SV 450p 7BGUIC 200p BC212 3 16p BU180A 120p TIP122 80p 2N3904 18p iNa4003 4 6p 3A400V 45p 74162 90p 74 5181 180p 74525 250p 4560 120P wasoT 350p79GUIC 225p BC214 38p BU205 200p TIP125 75p 2N3906 318p iNa4005 6p BA600V 180p
114. 0UHF UHF driver amplifier 10dB gain Maximum output 30dBmV Power require ment 14V 10mA TS1040S Single channel UHF driver amplifier 0dB gain Maximum output 40dBmV Power requirement 14V 10mA Quote channel required DISTRIBUTION AMPLIFIERS TE2042 Domestic distribution amplifier 1 input 1 output Gain 20dB Maximum output 42dBmV TE1638 Domestic distribution amplifier 1 input 2 outputs Gain 16dB Maximum output 2 at 38dB mV TS2046 40 860MHz Gain 20dB UHF 18dB VHF Maximum output 46dBmV TS2846 40 860MHz Gain 28dB UHF 2208 VHF Maximum output 46dBmV TS2845 eiat UHF UHF inputs Gain 28dB UHF 22dB VHF Maximum output m 182054 40 860MHz Gain 20dB UHF 18dB VHF Maximum output 54dBmV TS2060 40 860MHz Gain 200B UHF 18dB VHF Maximum output 60dBmV CHANNEL CONVERTERS TS5565 Gain 55dB UHF 55dB VHF 42dB FM Maximum output 65dBmV TCUU UHF UHF Single channel converter Gain adjustable 2dB 16dB Maxi mum output 26dBmV Crystal controlled oscillator Power requirement REPEATER AMPLIFIERS 14V 25mA Quote Channels required TSC3660 Repeater Gain 16 36dB UHF 10 30dB VHF Maximum output 60dBmV As TCUU except UHF to VHF converter Quote Channels required TSC3665 Repeater Gain 16 3648 UHF 10 30dB VHF Maximum output 65dBmV As TCUU except VHF to UHF converter Quote Channels required TSC3060 Repeater Gain 10 30dB VHF Maximum output 60dBmV QUALITY AT LOW COST TAYLOR BROS OLDHAM LTD LEE STREET OLDHAM TEL 061 652 3221 TELEX
115. 10 Values 720 937 50 DTL GATE CER Resistors 5 00 41pf 160V Polystyrene per 200 Ye Watt Metal Film 1 50ppm lOr 1mg E24 200 Range 960 Resistors 25 00 470pf 50V DISC CER per 1 000 10 00 3300pf 500V DISC CER per 1 000 344 0 022mf 400V Polyester Price 10 00 1 00 Mnfrs Device OPCOA OPB8150PTO each LMDA PMD 11K 80 Power Darlington per 250 each f100 0 01mf 400V Polyester Ax per TI 2S 103NPN TO 18 KILSPEC 100 each 1 00 PLESSEY 0 47m 250V X Radial Poly RW 153P each 5 00 each TI 2N 1302 NPN GE T05 each 0 48 10mi 25V Bead Tant per 100 SE 2N 2711 PNP S Signal each 0 06 10000mf 40V Comp Grade T 2N 5450 Small Signal each 0 05 each TI 2N 5838 NPN Power TD3 each MC 14433 each 27pf 63V CER Plate per 1000 5 00 2 50 0 25 10 00 LORLIN 2 00 FRE CATALOGUE Sent to every customer 1 00 5 00 10 00 Terms C W O 75p p amp p Dept WW 45 Church Street Enfield Middlesex CIRCLE 060 FOR FURTHER DETAILS VIDEO TERMINAL BOARD K 80 characters X 24 lines W Requires ASCII encoded keyboard and monitor to make fully configurable intelligent terminal Uses 6802 micro and 6845 controller Program and character generator 7 X 9 matrix with descenders in two 2716 EPROM s Full scrolling at 9600 baud with 8 switch selectable rates RS232 interface Bare board with 2 EPROMS and program listing 48 plus VAT Send for details or CWO to A M Electronics A Wood Farm Leisto
116. 15 00 01303 2 50 2SCB29B 0 25 25c 972 00 MAF 240 24 50 PT8831 2 75 501316 210 25CB890 850 2Sc 978 7 50 MAF243 35 00 Pr8837 1000 SD1317 8 00 25C89 18 00 25c200 45 MRF245 30 00 Pr8838 15 00 501405 21 00 25C900 25C2026 75 MAF247 30 10 Pr8854B 18 00 SD1407 27 50 2SC900F 19 25c2053 0 80 MAF260 5 o0 P78861A 15 00 SD1407MP 55 00 2SC908 450 25C2097 36 00 MRF264 11 00 PTB864A 30 00 S01410 21 06 2SC9 A 18 00 25c2099 5 00 MAF309 12 00 Prag 18 00 S014101 21 00 28C945 21 285c2100 24 00 MRF316 55 00 Pra795 12 50 5014103 2 00 2SC9a5R 0 21 25c2103 00 MRF317 73 00 pr9797 14 00 501412 36 00 29C952 0 60 25C2105 15 00 MRF321 35 00 erasa 1600 01112 3 24 00 2SC982 0 30 2SC21 6 1 60 MRF323 35 00 Pr9847 16 00 SO14 3 18 00 2scaga 2 50 28c2118 3 0D MRF326 63 00 501005 a 20 501414 36 00 25c998 3 90 25c222 50 MRF327 70 00 S01006 210 S0 2 6 33 00 28C100 9 90 28C2233 9D MRF 329 58 06 S501012 3 10 00 501418 30 00 2SC1011 15 00 2 2237 00 MRFa12 18 51 5010024 10 50 S0142 36 00 2SC 070 15 25c228 3 00 MRFa2 6 85 50 013 000 SD1a28 24 00 2SC 096L 0 90 2SC228 9 00 MRF422 12 S010146 10 50 S011429 15 98 2SC1096M 90 25c2287 11 00 MRFA426 23 01015 2sciii7 50 25c2289 2 50 MRF127A 21 S010 8 6 3 i I PRODUCTS Backward Wave Oscillators Magnetrons Solid State Replacements Camera Tubes Cathode Ray Tu bes Cold Cathode Tubes Diodes Dis
117. 2 00each Pye Modulation Meter 68 510Mhz Type MM1 60 MESL Sweep Oscillator Type M10008 12Ghz 125 Circulators 590 720 Mhz N sockets 25 Airmec Sweep Signal Generator 20Hz 200Khz Electrohome 9 Video Monitor metal case 50 Transislors Type 2N3055 4for 1 00 Type 352 45 Artec20 Video Monitor metal case 40 Transtormers 30 volt 1 amp 1 00 Marconi Universal Bridge lype TF 8688 10 ITT20 amp 24 Video Monitors wooden case 30 Transformers 36 volt 1 5 amp 1 00 Marconi Universal Bridge Type TF 1313 220 General Radio Microwave Oscillator Type 13608 17 41Ghz 125 Transformers 600 0 600 250mA plus 460 0 460 4230mA 10 00 Tektronix Oscilloscope Type 647 250 Wayne Kerr Component Bridge Type B521 45 Variacs 2 amp 5 amp 8 amp 15 amp 20 amp 25 amp Tektronix Oscilloscope Type R647A Less Plugins 196 Marconi Oscillator Type TF 1246 40Kh 50Mhz 95 Loudspeakers Richard Allan Type CP12 12 150hm 6 00 EMI Wide Band Amplifier Plug in Type 7 1 25 Wandel amp Gollermann Level Meter Type TFPM 13 10Khz 14Mhz 60 Capacitors 16 mtd 6 5kv 25each 0 33 mtd 1 kv 4 00 each Advance Oscilloscope Type OS15ALP Tube 3Mhz 85 Advance Oscilloscope Type 05254 Twin Beam 3Mhz 125 H Tektronix Oscilloscope Type 502 85 PYE POCKETFONE PF1 UHF RECEIVER 440 470 MHz Singie Channel int speaker and aerial Supplied complete with rechargeable battery and service manual 6 each plus 1 p p plus V A T P
118. 200 UCH42 135 2C42 29 50 GAWBA 2 95 6S4A 150 30P12 100 6136 2 50 t80CF 11 00 gr3jA 2 90 GS 2D 12 00 pgs 0 75 QS1210 1 50 UCHB 0 65 2c51 9 75 eB8G 1 50 6 7 110 30P38 0 60 6146B8 750 E80F 13 50 EF39 110 GTIC 14 00 pco 350 QS1211 150 UF85 120 2C53 3200 6BA6 0 95 6SA7GT 1 00 3 P19 100 6157 2 50 EB0L 1150 Fai 350 GTICS S13 00 5695 110 QS1212 320 UF41 145 2CY5 150 6BA7 450 6SC7 150 opii 2 50 6201 6 95 EBICC 350 gra 350 GTE175M 8 00 pCaoo 110 QS1213 5 00 UF42 1 15 2021 0 95 6BABA 3 50 6SG7 120 30PL13 0 60 6211 250 ESIL 1200 efso 250 GTRISOW 1 00 pcooo 425 QS1215 210 UF80 0 80 2021W 250 ece 100 6SH7 120 3op i4 175 6267 150 E82CC 3 50 Eres 495 GU20 3500 pcs oso QS1218 5 00 UF89 2 50 2E26 7 95 6BD4 150 6SJ7GT 120 33A 158M 6350 2 00 E83CC 350 EFF 150 GXUI 13 50 pcCgs os QU37 950 UL4 3 50 2J42 93 00 68D6 1 00 6SK7 0 80 19 50 6360 5 50 EB3F 5 50 EF72 120 GXU3 2400 p ga 979 QU37 1150 ULB 0 85 2K25 2495 6BE6 0 72 6SK7GT 1 20 35 5 4 50 6386 1450 E86C 9 50 Epj3 100 GXUSOSS PCC89 070 QVO3 12 495 UUS 250 2K26 95 00 6BF5 1 60 6SL7GT 0 85 35L6GT 2 00 6545 8 50 EB8C 795 trap 055 1450 pCcigg 70 QVOS25 175 UU7 8 00 34 1078 12 00 68G6G 3 00 6SN7GT 0 95 3sw4 070 6550A B00 EBBCC 3 50 Erga 3 50 GYS0 1 20 pcCgos 979 QVO6 202950 UU8 9 00 3A 108A 9 00 6BH6 19
119. 235 reatech up lectronics DISPLAY amp COMMUNICATION PRODUCTS 85 48 35 90 31 31 90 110 485 144 375 525 250 320 51 51 142 142 36 295 129 72 95 20 22 28 30 120 x 2 d 0oo0o0moco UNN SUNN NNN 120 220 215 O N N EN NU NH M o0 00 00 00 60 95 o0 75 95 95 a5 25 00 50 00 NEW VALVES National Varian Mullard RCA ITT NT2 PCL805 PL509 PL519 QOvO2 6 QQVvQ3 10 Qavo7 50 QvQ3 12 OY3 65 QY3 125 QY4 250 A1169 RG3 1250 RG3 250A RG4 1250 RG4 3000 RM126 RR3 250 RR3 1250 SP41 SSA 13 T 60L T2888HOG TB2 5 300 TY5 500 Uus VLS63 VATS VA1SO MCN XG 2500 XG2 500 XG2 6400 XG5 500 XAI 1600A XR1 3200 XR1 6400 Y6028 2803U zT1019 20100551 ZM1000 2M 00 2M1020 OA2 OA2WA OA3 082 082WA Qe3 oca Q03 182134 1835A 863A 18638 1p21 1P28 2AS15A 2C39A 2C39WA 2021 2 26 2542 255 2K25 3C X10004 3CX1500A7 a 654 a 125A 4 250A 4 400A 44008 4 400 4832 4C35A ACX250B 4CK2508 ACX350A ACX350A ACX350F ACX 500A iCx soog 4 X 00000 4021 1032 4PR60C 4X150A 5 500A SARA 5ASAA 5B254M 5c22 5CX1500A 5022 5R4 SA4GYA B SRAWGB 5SR6 5U4GB8 SUP 5VaGA 524GT 6AH6 6AJB8 6AKS 6AKSW AKG 6ALS 6ALSW 5AMS 6AM6 GANBA 5AQSA 5AQ5W 64Q8 BARS 6AS6 6AS7G 6AUSGT 6AUBA nouu 12 52 49 59 80 35 15 a8 30 1360 15 34 12 29 589 112 225 25 14 51 36 152 24 29
120. 27 DISC 2 250p 7414 sop EZEELLIEE 7415367 55p 7 150p CA3059 350p LM747 70p TBA800 80p 550p 580510712 9 SFF96364 E8 CONTROL tL 7416 POA 74LS00 POAI00p 74LS368 55p 80p CA3060 350p LM748 40p BA810 100p 3 550p TMS9918 300p 210p 7417 POA 24500 POP 74 S373POAN0p 4 250p CA3080E 80p LM1011 480p TBAS20 80p 0 35 TTY tMso027 18 30p 74L802 36b 7ALS37APOA350 4040 80p CA3086 60p LM1014 150p TBA9SO 225p 950p 2 2 T MS9928 20 275p HECNEIE AE oe Penser Han Seb erus E Pu Ses Dese Ee Un Be F 3 4LS37 A 1830 8C oA ALSD4 POATOOR Jj i7 1200 75b 375p LM1871 300p TCA220 350p 3600p 2112A 300p LIES us 32 6 150p 4 36p 74LS379 120 75p CA3130E 90p LM1872 300p TCA270 350p 1 12 21 42L 220p ICs 3 5795 1305 36P 73190 930p 30p T 110p M1886 500p TCAS40 175p TMS9980 20 2114 4 220p uU E 36P 3415393 150p 85p 60p LM1889 350p TDA1004A 4 TMS9995 12 214 450p AD558CJ 775p 4194 2005 36P 74LS395A 120 60p CA3140T 110p LM2917 250p TDA1010 250p 1450p 40273 300p anegiy 20 443 125p Sep 748399 150p 48p CA3160E 100p LM3302 75p TDA1022 500p 24 4116 15 160p AM25S10 350p TMS9909 12 2608 250p P 340 100p 48p CA3161E 150p 50p TDA1024 120p 0 300p 4116 20 340P AM25L52521 WD2793 4200p 49152 250 30P 4LSa65 180p 80p CA3162E 450p 120p TDA1170 300p 400p 41183 450p 250p WD2797 4200p 50 175b 50P jarSa67 180p 80p CA3189E 300p 160p TOA2002 325p Z
121. 2A 68732 0 68732 1 68766 68764 2764 2564 MK2764 25128 27128 EXPORT ENQUIRIES WELCOME Tei Plymouth 0752 332961 Telex 42513
122. 30p 100p 8156 750p 745288 180p 62487 300p 7486 40p 74 890 40p 4094 100b FF13331 asop Nees Geb ULN2O04 pep 8205 225P 345387 225p MC4024 325p UARTs Tass 280p A9 ep Jesoo Mbp 4095 30b LAHEY 3800 ESSE SOR UNA Ue 8212 30 as dep Moos 325p EMEN 7490A 50p 74L592 585p 74 LM301A 25p ULN2068 290p P AY 3 1015P gt S04 60p 4097 290p NE565 150p 8224 200p EPROMs 75107 90p MC6818P 550 Jola dep matasa Soe maos cop ang gap LU Sep NES grop Ui ee soo ap BUE AS ELA EEN s09 7i S96 75p 74508 60p 4099 90p LM30BCN 78D NES67 140p ULN2803 200P 8228 250p 2532 450p 75114 15 160p 300p 800p 7494 1205 74LS107 48p 74S10 45p 4501 40p Matt ae NE570 400p UPC575 2755 8242 550p 2532 30 700p 25121 22 140P coM8017 300p MSM5832RS 7495A Ssh 748109 48p 74811 Sop 4502 60P EM318 150p NESZ 400p Jpcsg2H 2009 8250 1150p 2564 700p 75150P 120p iM6402 360p 350p 2496 255 745112 48p 74520 45p 4503 60p M319 tas NE592 75p UPC1156H t 8251A 100p 2708 400p 75154 140P TR1602 300p 497 2505 74L5113 48p 74922 Sop 4504 S0p 324 0 NES532P 200p 151135 356 8253C 5 100p 2716 350p 75159 220p TELETEXT SAG 1805 74LS114 aap 74930 45p 4505 400p tM3saz Sop NE5533 160p coo FEAS 8255AC 51150p 2732 450p 75365 150p ZIF SKTS 74100 BOP 3rS122 eon 74532 7op 4506 320p LM3347 90D NES534P 120p KAZI doop 8256 36 2732A 2 900p 75451 2 72p DECODER 7
123. 3385 ae 9x030 240 260 Realistic delivery for volume 13017 30 30 050 3x028 110 072 5x026 40440 200 7x025 45 45 333 orders 31029 220 036 5x028 170 145 7x033 50450 300 No price penalty for call off 3x030 240 033 51029 220 072 7x028 110 272 orders 5x030 240 066 7x029 220 136 7x030 240 125 Prices including P amp P and VAT Mait Order Please make your crossed VA Size VA Size cheques or postal orders payable to ILP Post to ILP Electronics Ltd Dept 3 15 0 7 43 160 5 12 90 Electronics Ltd Graham Bell House Roper Close 20 n aaa 25 5 16 ES Trade We will open your credit account Canterbury Kent CT2 7EP 80 3 1081 500 8 2573 immediately upon receipt of your first Tel 0227 54778 Telex 965780 120 4 31173 625 9 3163 order For 110V primary insert O in place of X in type number For 220V primary Europe insert 1 in place of X in type number For 240V primary UK insert 2 in place of X in type number IMPORTANT Regulation All voltages quoted are FULL LOAD Please add regulation figure to secondary voltage to obtain off load voltage ScrLes E NH ELECTRONICS LTD C0030 AG 202A PR GO2A PR 6O1A ob 402 VMOS High Sensitivity 5MHz Oscilloscope RC Oscillator Regulated DC Power Supply Regulated DC Power Supply Wideband RF Signat Generator High Sensitivity Electronic Voltmeter FET VOM House of instruments Ltd Clifton Chambers 62 High Street Saffron Walden Essex
124. 345 45 carriage and VAT Comprehensive range of TRANSFORMERS LT ISOLATION amp AUTO 110 240V Either cased with American socket and mains lead or open trame type available for imrnediate delivery Leaflet on request 12V D C BILGE PUMPS 700 G P H 10ft head 3 5amp 11 50 1 50 p amp p 14 95 inc VAT 1750 G P H 15ft head Samy 15 00 1 75 p amp p 19 26 inc VAT SINGLE DIAPHRAGM COMPRESSOR Max 20 PSI One CFM approx 240 volts AC 18 2 p amp p 23 inc VAT EPROM ERASURE KIT Why waste money Build your own EPROM ERASURE for a traction of the price of a made up unit Complete kit of parts less case to include 12 8 watt 2537 Angst Tube Ballast unit pair of bi pin leads Neon indicator safety microswitch on off switch and circuit LESS CASE Price 13 60 75p p amp p Total inc VAT 16 50 Warning Tube used in this circuit is h ghly dangerous to the eyes Unit must be fitted in suitable case FROM STOCK AT PRICES THAT DEFY COMPETITION AC GEARED MOTORS C F BLOWERS DC MOTORS AC CAPACITORS MICROSWITCHES STROBE KITS RELAYS FLASHTUBES REED SWITCHES CONTACTORS SOLENOIDS A C or D C SYNCHRONOUS PROGRAMME TIMERS MOTORS Phone in your enquiries SERVICE TRADING CO 57 BRIDGMAN ROAD CHISWICK LONDON W4 5BB 01 995 1560 ACCOUNT CUSTOMERS MIN ORDER 10 CIRCLE 038 FOR FURTHER DETAILS Superior Quality Precision Made Poo NEW POWER RHEOSTATS es 1 5k1 3 80 30p amp p 4 71 inc VAT 50 WA
125. 3706 0 12 AF126 0 32 BC284 0 30 BF127 0 24 BT119 2 35 2N3708 0 12 AF127 0 40 8C300 0 30 BFIS4 032 BT120 1 65 2N3773 195 4 AF139 040 BC301 0 30 BF 58 022 BU10S 122 2N3792 1 35 THE POWERFET AF178 1 95 8C303 026 BFI60 0 27 BU108 1 69 2N4427 1 50 e n e Cc n C AF239 042 BC3078 009 BF167 024 BU124 125 2N4444 1 15 SPECIALISTS AUI06 325 BC327 030 BF173 022 BU125 125 2N5294 0 42 AUTO 2 00 BC328 0 10 BF177 038 80126 1 60 2N5296 0 48 BCIO7A 0 11 BC337 010 8F178 026 BU204 155 2N5298 0 60 8C 07B 0 11 BC338 0 09 Bf 79 0 34 BU205 130 2N5496 0 65 8C108 0 10 8C347A 0 13 Bf 80 029 BU208 1 39 2SA715 0 60 U RS BC108A 0 11 8C46 035 BF181 0 29 BU208A 1 52 25C495 0 80 BC108B 0 12 BC478 020 BF 82 0 29 8U2080 185 2SC496 0 80 BC 09 0 10 BC527 020 BFI83 029 8U326 1 20 2SC1096 0 80 Pantechnic present the most adaptable high powered amplifier ever BC1098 0 12 8C547 010 8F 84 028 8U407 124 2SC1106 2 50 BC109C 0 12 BC548 0 10 Br185 0 28 BUS00 2 25 28C1172 220 BCI14 01 BC549A 008 BFIS4 0 BU526 1 90 SC1173 41 FET SYSTEM amp 8Ch6A 0 15 BC550 0 08 BFI9S 0 13 BUY69B 1 70 28C1306 1 00 Features gc 0 19 BC557 0 08 origa 0 11 MJ3000 1 98 2SC1307 1 50 uf C119 024 BC5578 0 08 197 9n MJE340 0 40 2SC1364 0 50 SE SMOKE pu 2kW single ended 8C125 025 BCBS8 010 BEI98 016 MuES20 0o48 28C1449 080 s Cubic foot inc Heatsink BC139 020 BCY33A 1 60 BFI99 0 14 MPSA13
126. 39 2 75 GSSIK 12 00 MX168 50 00 QQV06 10A UBF89 1 50 3C23 25 00 6BR8A 3 50 724 200 1624 4 00 4CX250B 6 50 E86C 8 25 EF40 5 00 G1802M 17 50 N7x 15 00 65 4 UCC84 125 3C45 24 50 6BS7 6 00 11E3 55 00 1625 3 50 TV Devices E88C 8 25 EF4l 3 50 G2402D 12 0 OA2 325 QQV07 50 68 60 UCCSS 1 85 3CXIO0AS 6BW6 6 00 12AH8 5 00 2050 7 50 Large stacks E88C 842 EF42 450 G400 1K 17 50 OA3 2 50 QQZ06 10A UCFK0 2 00 47 00 SBW7 150 W2AT6 150 MiZb sud ou Prices on E9CC 9 47 EF50 2 50 GN4 9 00 OA4 6 00 62 20 UCH42 2 50 3529 45 00 6BX7GT 5 00 12AT7 175 4212H 300 00 application E90F 9 90 EF54 5 00 GN4A 9 00 OB2 4 35 QU37 12 50 UCIS8 2 50 384 2 00 6BZ6 2 75 12AU6 150 5544 81 97 E9IH 6 25 EF55 3 50 GS16 16 00 OB3 2 50 QV03 12 6 80 UCLS2 1 75 3V4 1 75 6C4 1 25 12AU7 125 5545 102 00 8 75 EF80 1 75 15 00 O0C2 4 35 QV04 7 350 k 2 75 465A 60 00 amp CB6A 2 50 12AV6 2 50 5551A 114 90 9 10 EF83 4 00 20 00 QV08 100 155 70 4125A 60 00 i 6CD6GA 5 00 12AV7 3 50 5552A 15535 7495 0 7 74136 0 51 74175 1 0 ASA INTEGRATED CIREUITS 7496 082 74141 0 89 74176 Vis TBAsiOn 138 i i 7497 315 7442 1 30 TB S j BASES CRTs SADPI 35 00 VCRSI7B 10 00 Den 016 n a3 zo ae 74100 1 54 74143 2 60 A L TBASSUQ i aK SCP1 1000 VCRSUC 10 00 740 017 7427 0 30 7472 0 33 74107 045 7444 2 60 74180 130 TBAS60CQ 3 22 ARI 8 50 SCPIA 40 00 7403 0 1
127. 40 S001752 750 2N5590 8 50 25C1251 10 00 25C2545 029 MRFa75 2 00 501115 7 210 2N5591 8 90 25C1260 111 BRF90 1 50 MRFA7S 25 S027 250 2N5643 13 00 28C 1303 500 8RF91 200 MRF477 12 50 509131 325 285913 2 50 25C 1306 100 BRF96 2 00 MRF492 27 50 501133 9 50 2N5945 8 95 25C 1307 50 BF Y90 50 MRF497 18 50 501133 1 10 00 2N5946 1563 2SC1311 0 40 BLw29 10 00 MRFS 5 330 S01 34 2 50 2N6080 6 00 28c1311 0 32 BL weoc 15 00 MAFS17 3 50 S501134 2 10 00 2N6081 8 75 2Sc1314 25 00 BLWEOCF 15 00 MRF620 18 00 501134 8 10 00 2N6082 9 00 25 1318 0 40 BL weaca 65 00 mMRF644 27 50 501134 STUD 7 60 2N6083 12 00 25C 3688 00 BL w78 61 80 MRF646 28 00 501135 1025 2N6084 13 20 25C13838 0 50 B w amp o 10 25 MAF64B 33 00 01 35 12 00 2N6094 8 00 25C 1424 1 35 ec we 14 90 MAF750 6 50 01136 12 50 2N6095 8 50 25c1509 6 00 BLW90 13 00 MRF846 46 00 SO1143 945 2N6255 345 25C1546 0 a5 GL w9B 110 00 MRF9O1 275 S01123 10 00 28C382 0 65 25C1 568 045 BLx39 13 75 MAF904 2 95 S011144 250 28C458 0 22 28c1589 500 B x65 2a5 MRF91 2 so so1158 795 2SC4588 0 36 28c1622 0 33 BL xezc 9 50 MAFS175 22 50 501201 2135 25C458C 0 22 28c1623 0 30 BLxe7CF 9 50 MAF5176 30 00 501202 50 28C460 0 25 25C1688 19 80 BLx68C3 10 00 MAF5177 a3 00 501212 0 6 00 2SC460B 0 25 28C1674 025 BLX6eBCF 10 50 MRF8004 200 S012127 400 2SC461B 0 25 281675 0 20 BLX69A 2
128. 41 x AVO SIGNAL GENERATORS AFM2 x We have in stock a quantity of AVO type AFM2 signal generators supplied in fully tested working condition Complete with accessories Spec as follows 0 45MHz 225MHz in 8 bands AM ail bands plus FM on two bands covering 20 100MHz Output 1uV 50mV and 200mV High O P setting m c set level meter scale shift for accurate frequency calibration variable mod etc PRICE EACH JUST 55 VAT Carriage each 4 E z SWEEPERS x TEKTRONIX System 800 1500MHz 325 FILE MANAGER SYSTEM MODEL TELOMC 200s Sem SUOMI 4907 Option 31 Third disc drive TELONIC SM2000 with 0 10MHz plug in 150 GPIB IEEE 488 1975 compatible PLEASE NOTE All the pre owned equipment shown has been carefully tested in our workshop and reconditioned where necessary It is sold in first class operational condition and most items carry a three months guarantee For our mail order customers we have a money back scheme x COMPUTER PERIPHERALS x 1 6MB 8 FLOPPY DISC DRIVES New Stock After our recent sell out of the DRE7100 FDDs we are pleased to offer another bargain package as follows BRAND NEW American MFE Corp model M 700 DOUBLE SIDED 8 Disc Drives Massive storage capability up to 1 6MBytes Full IBM compatability External power requirements are 5V at 1 2A and 24V at 11A Full spares back up available U K Elcomatic s Current list is over 315 OUR PRICE JUST 175 VAT in cluding full
129. 4109 P 74LS123 120p 74537 60p 4507 asp L 408 NESS34AP 200p yo 5511 5755 8257C 5 750p 2732A 35 550p 75453 4 72p TEXTOOL SAA5020 600p FS 45P jaiSi94 629 Y0p 74951 75p 4508 160p 339 eoP PLLO2A 500p X222 ToP 8259C 5 750p 2764 25 900p 75491 2 868p 24pin SAA5030 700p 2219 Ha 74 8125 60p 74974 75p 4510 75p LMssap eop RC4 36 80p N4114 80p 8279 750p 27128 25 2500p 8126 120p 28 pin SAASO4 16 D ER 7418126 60p 74985 250p 451 75P 4377 3965 S566B 300p gc 190p 8284 600p 27128 30 2200p 8728 120p 40 pin SAA5050 900p 74118 150p 74L5132 S p 74886 90p 4512 75p LMa80 J5p SAA 90 E16 ZNa23t 130p r 74119 150p 74L5133 48p 74S p 1 140P w381AN 180p ZN424E 130p MMOD Te tae 43 3 A RE WRAP SOCKETS BY TI 7420 180p 748136 60p 749113 Sop di 180p LMGS2 120p 1150P 2N425E 350p 74121 45p 74LS138 90p ZN426E 300p 8pin Sp 8pin 16p 24pin 24p 8pin 30p iBpin 50 4pin 7 74122 S amp p 74LS139 60p 745124 400p 4516 75 VAAL SH N42 coop pin 1p 20pin 18p 2806 260 14pin a2p 20pin 66 jain 1905 74123 90p 74 8145 100p 745132 110p 17 00p ZN428E 450p i6pi tip 22pin 22p 40pin 30p 6pin 45p 22pin 75 p 5 T p p p D P 40pin 130p 74125 Sop 748147 150p 745133 Gop 1818 Tee ass ZN429E 210p E e e lia i 74126 60p 74LS148 150 1A ve Y ZNA450E 750i 7418 Job 74LS151 70p 745139 120p 4520 75p sy 7805 40p 7905 45p SNaegcp 3o0p BFRBO 1 32p TIP3IC 4Sp
130. 4x015 22 22 272 6x017 375 8x033 50 50 500 equipment 0 013 15415 050 213016 25425 180 4x016 25 25 240 6x018 321 8x042 55 55 45a High effici bli 0x04 18 18 042 2 017 30 30 0 83 4x017 30 30 200 6x026 281 8x028 110 454 gn efficiency enabling RR E 935 2x028 110 045 4x018 35 35 171 6x025 250 8x029 220 227 conservative rating whilst main On 25 3 2x029 220 0 22 4x028 110 09 61033 225 8x030 240 208 i i 0x017 30 30 025 21030 240 020 4x029 220 054 6x028 204 625 VA dcos c A 4 4 050 6x029 102 3 encased in ABS plastic a M VA i i x030 n JA 5 Ere Nos 140 x 75mm ME 9 imm egulation 70 x ane 0 45Kg Regulation 12 s 110 x 40mm 1 8Kg 300 VA 5 Why ILP ia Regulation 8 110 x 50mm 2 6Kg 9x017 30 30 193 Ex stock delivery for small Regulation 31010 6 6 6 64 E Regulation 6 9x018 35 35 892 1010 6 6 50 3x01 9 9 aaa UA EAT pie 9x026 40 40 78 quantities 2 3 9 540 12 1 7x013 15 15 10 00 i i 14011 9 9 166 012 12 12 333 81013 15415 533 Tota 8 18 3g 9 025 EAR EA Gold service available 21 days 1x012 12 12 125 SU 5 ER 266 5x914 18 18 444 73015 22 22 682 9x042 55 55 568 manufacture for urgent deliveries 1x013 105515 100 3x014 18418 222 5x015 22 22 363 4016 25 25 6 00 9x028 110 5 68 1 014 18418 083 3101 EEG e 3016 25 25 320 7x017 30 30 500 9x029 220 2 84 5year no quibble guarantee 1 015 22 22 068 O16 Y 8 5x017 30 30 2 66 7x018 35435 428 2 listi i IEEE d oes 34017 30 30 133 RM etus zen TAOS
131. 5 6507 0 80 3673 1 85 6870 11 50 E90CC 850 Ergs oso GY802 100 pecgos ogo QVOB 100 UY41 3 50 3A 1098 11 00 68H8 150 6SS7 1 95 38HE7 450 68838 995 E90F 795 Erge 125 GZ30 00 p es2 ogo 14500 UY85 070 3A 110B 1200 68J6 120 6U4GT 175 pkD6 550 6973 375 E91H 450 EF86 Special G23 1 00 perso 065 QY3 125 49 50 V235A 1K 3A 141K 1150 6BK4 400 6U5G 1 50 4j 6 00 7025 250 ES2CC 3 95 G232 1 00 60 QY4 250 65 00 250 00 3A 147J 7 50 6BK7A 1 95 6UB 9 85 socs 0 95 7027A 465 quality 2 50 PCF82 0 60 E99F 6 99 egg oss 6Gz33 450 perga oes OY4 400 71 95 V240C 2K 3A 167M 10 00 6BM8 0 58 6U8A 150 50CD6G 115 7032 2 00 E130L 19 95 Egi 150 G234 2 15 pcre 20 RIO 400 225 00 3A2 3 95 6BN4 4 65 6V6GT 085 Soye 295 7059 250 ElBoCc 6s0 Ere 259 6237 450 pcpg oso RIS 12 00 V241C 1K 3A3A 395 6BN6 1 65 6X2N 00 zokU 200 7189 250 E182CC 9 00 faz 095 HAA9 100 Perso Seo R17 1 50 195 00 3A4 110 68N7 450 6X4 9 956 gisPT 450 7193 780 E180F 650 Ef94 0 95 HABCBO0 0 90 perso 189 R18 250 V246A 2K 3ALS 9 95 6BN8 2 75 6X5GT 055 3581 250 7199 5 95 E186F 850 EF95 100 HBC90 075 pcrgoo oso R19 250 315 00 3AT2 3 35 6BQ5 075 6X5GTY 1 00 zci 295 7247 2 00 E280F 19 50 EF37 0 50 HBC9 0 80 pergo 135 R20 1 20 V339 3 50 3AW2 3 35 6807A 0 72 6X8A 225 94 3 00 7360 9 50 E283CC 10 00 Efgg o9 HF
132. 5 6HGB 50 6HS6 95 6HZ6 5 6J5 15 645GT 295 66 20 6J6A 3 00 6 85 400 6486A 65 6JC6A 3 50 6JESC 49 6JG6A 85 6JHE 25 5JK6 2 6 M6 3 95 j 6JS6C 395 exscr 7 5kB a erii 255 6x06 9c 6KD8 5KE8 9i j 6KGE 6KMB 6KNB 6Kx8 6L6GC 35 jere METAL 6LF6 4 5LNB 2 6LO6 4 95 6M11 a 80 5MJS 3 COIR 255 6Sar 3 00 esu7Gr 195 6SN7GTB 6SR7 6ua susa eva 6VEGT 6x4 2 00 5X5GT as 6X8A 3 00 6vo 295 TFT 950 KT 10 85 8CG7 200 aro 2 00 aspa a8 00 12AT6 70 12AT7 60 12AU6 2 00 12AUTA 160 12AV6 WIRELESS WORLD MAY 1984 12Ax7 12AX7WA 1284A 12BA6 12BA7 128E6 128M7A 120Y7A 12826 120K6 120w7 1261 12FQ8 12GN7A 12K7GT 128U7GT 1361 2145Z6 30KD6 40KG6 40KG6A 42EC4 75C 83A soc 90CG 90cv 15082 1802 150C3 150C3 212 290A 350A 3508 403A 5728 575A 615 710 740L 760P 805 807 aio aria 812A 813 813 8298 833A B43 845 8578 866A 868 872A 922 927 930 931A 9318 934 935 10510 1052S 2050 2050A 4532U 1833U 4875U 5544 5545 55514 5552A 5557 5559 5581 5582 5583 5632 5636 5612 564a 5651 5654 5665 5670 66A 5867A s868 5869 5870L 5870ST 5876A 5879 5886 5894A 58948 592 5963 5965 599 6005 6011 6012 6014 6021 6058 6063 6065 6073 5080 6083 6084 NAT RCA 888 50 40 70 50 25 00 00 80 95 40 50 75 00 80 50 oo 20 50 10 95 450 00 00 50 50 o0 50 o0 50 90 80 50 00 2 90 00 90 90 50 00
133. 5 TAE 1 65 THAGEIH 220 TDA2571 2 96 VOLTAGES amp TIMES AN7150 2 95 MC145106P 1 150 TDA2581 2 25 BA521 3 35 7 95 TA7146 2 95 TBA720A 2 45 1OA2593 2 95 3 15 VAT CA13520E 1 5 MC1723 0 50 TA7176AP 2 95 TBA7500 2 65 TDA2600 5 50 5 Securicor CA3086 0 46 MC3357 2 75 TA7203 2 95 TBA800 089 TDA2610 2 50 ETI6016 2 50 ML231B 175 TATZO 25 TES i5 TDA2611A 1 95 HA1377 3 50 ML232B 250 2 15 j TDA2640 2 60 The YC1000L is a laboratory grade instrument with versatile HATiSeW 150 MSMSB07 6 75 TA7222AP 180 TBAB20M 0 75 TDA2680A 2 75 microprocessor control It includes a frequency 10Hz 600MHz 0 02 HA1339A 2 95 PLLOZA 5 75 TAT227P yA 28 TBA8200 146 TDA2690 2 45 ppm a period 0 1S to 0 1uS and a pulse counter 0 99 999 999 TTL HASS 205 SAA OOA 359 UAL reo TBABSD au TDA3560 550 level a voltmeter AC or DC to 999V 3 ranges a thermometer LA4302 295 SAA5010 6 35 TA7321P 225 TBAS50 2X 235 UPC575C2 2 75 remote sensor 29 0 to 99 9 C plus a precision timer 24 hour LA4250 295 SASo60S 75 TCR 345 TBASTU TH UPC 1025H 2 50 all i H clock providing event or period local or remote and alarm func tage ale SAREN 2086 TAASSQ 025 TBAI441 215 mese tions Display is via 8 large fluorescent green digits and or the inbuilt LA4422 2 50 SL9018 4 95 TAASIO ce 95 rae 136 UPC1156H 2 75 LAa430 2 50 SL9778 6 6 2 UPC1158H 0 75 5X7 20 characters line 2 line second Dot Matrix thermal printer ee tee i30 180
134. 50 723AB 125 00 7868 6 00 DM160 4 75 ECHS8 3 00 EY500A 3 00 M02901 115 00 PY82 1 50 303 60 2j70A 383 00 6BC4 4 00 6U8A 2 25 803 25 00 7895 12 00 DY87 1 50 ECH83 2 50 EY802 1 75 MUI4 2 50 PY83 2 50 T240 25 00 2 70B 336 00 6BE6 1 50 6V6GT 2 25 805 45 00 8005 110 49 DY802 1 50 ECH84 2 50 E235 1 75 MXIIS 55 00 PYSS 2 00 U18 20 3 50 2K25 12500 6BH6 2 50 6x4 2 00 807 335 3068 14 00 E55L 45 00 ECL80 1 50 EZ40 2 50 MX123 72 00 PYSOOA 4 00 uly 13 75 3 400Z 85 00 6BJ6 2 25 6X5GT 1 75 81IA 18 33 122 90 00 E80CC 8 81 ECL81 1 75 EZ4 2 50 MX145 56 70 PY800 1 50 U25 2 50 3 500Z 85 00 6BK4 4 50 7B7 2 50 812A 18 33 8136 2 50 E80CF 11 27 ECL82 1 50 EZ80 1 50 MXISD 1725 PY801 1 50 C26 2 50 3A5 3 00 6BL6 85 00 7CS 400 813 125 86 8417 6 00 E80F 14 19 ECL83 3 00 EZ81 1 50 MX152 131 25 QF451 82 50 Ui 12 00 3B24 11 00 6BL7GT 4 50 7C6 2 50 833A 193 16 18042 11 53 E80L 13 73 ECL84 1 50 EZ90 2 00 MX161 15225 QQV02 6 30 50 LABC80 1 25 3B28 15 5 6BM6 115 00 7H7 4 00 866A 20 03 18045 10 49 E8ICC 8 00 ECL85 1 50 FW4 500 3 50 MXI63 20 25 QQV0i1020 50 UAF42 2 50 3B29 20 05 6BN6 2 00 7R7 425 872A 20 00 E8IL 13 27 ECL86 1 75 FW4 800 3 50 MX164 25 52 QQV03 20A UB41 3 00 3B240M 17 50 6BQ7A 3 50 787 350 922 6 00 Tested E82CC 8 10 EF37A 500 GL371K 35 00 MX166 147 00 4838 UBCH 225 3BXUM 17 50 6BR7 90 7Y4 2 25 931A 18 50 Ex Equipment ES3XCC 840 EF
135. 50 n 0 99n A z nc nl nc 0 01 i Oext max sim A 28 1 WWW americanradiohistorv com and G int max 25 5 4l Fig 4 Light loss in a multimode fibre approaches the theoretical minimum except at the wavelengths associated with water impurities Fig 5 If the bandwidth of the fibre is insufficient then adjacent data pulses can be spread out to the extent of becoming indistinguishable Fig 6 Pulse spreading is much less noticeable with graded index fibres than with step index multimode fibres 42 OPTICAL FIBRES Mulfimode fibra 1982 idoped silica core LOSS dB km Rayleigh scattering limit 10 12 WAVELENGTH ym PULSE BROADENING ns km 001 0 02 Graded index 0 03 REFRACTIVE INDEX DIFFERENCE A nications point of view are signal attenuation and bandwidth Absorption of light by conver sion into heat and scattering principally determine the attenu ation of an optical fibre Recently developed laboratory fibres have attenuation figures approaching the limits set by Rayleigh scatter ing due to the intrinsic molecular inhomogeneities of glass At the popular wavelength of 0 85um low cost high lifetime alumi nium gallium arsenide e ds the Rayleigh scattering limit is about 2db km at a wavelength of 1 3um the limit is around 0 3dB km whilst at 1 55um the limit is as low as 0 15dB km Fig 4 Presently available commercial premium
136. 55 By including thermal design in the totality of board design it has been possible to 8C171B 0 10 BD182 0 70 BF422 0 32 R2540 2 48 reduce the size of the electronics and increase the efficiency of the transistor to BC172 0 10 BD201 0 83 BF457 0 32 RCA16334 0 90 heatsink th it Th bined eff f this h Ad d 8C1728 0 10 BD202 0 65 BF458 0 36 RCA16335 0 80 eatsin ermal circuit e combined effect of this has been to dramatically z 4 y increase the volumetric efficiency of the amplifier heatsink assembly The SYSTEM FUE p 10 REM ne EE ne ape Mor Amp offers 1 2kW of power in a space of 180mm x 102mm x 77mm excluding PSU BCi74 009 BD222 046 BF595 023 TIP29C 0 42 and Fan BC174A 0 09 BD223 0 48 8F597 025 TIP30C 0 43 The basis of this considerable advance is the PANTECH 74 Heat Exchanger BC177 015 8D225 0 48 BFR39 023 TIP31C 0 42 designed and manufactured Dy us By eliminating the laminar air flow found in BCIE oi 8C232 0 35 BFR40 0 23 TIP32C 042 conventional extruded heatsinks heat transfer to the environment is greatly OS IB BD233 035 JBFR4 Oade DIESE ovo enhanced BY199 0 40 N4004 0 05 The flexibility of the 1 2kW amp stems from its division into 4 potentially separate DIODES _al By aos D qut N4005 0 05 CRT TUBES amplifiers of 300W each downrateable with cost savings to 150W These can be AATI9 008 ETE ES Noo 296 T7 paralleled increasing current capability or seriesed bridged in pairs doubling BA115 0 13
137. 6 of the labour force was engaged in information process ing occupations Parker and Porat discussed political issues and headed part of a 1975 article with the phrase The Information Society The concept of an industry centred on a resource more important than oil information was introduced later Informa tion Technology Year IT 82 was launched to rub in the message Britain Needs Information Tech nology Before considering the outlook for the rest of the decade let me establish my forecasting credentials if any by conducting a brief post mortem on the 1978 article WIRELESS WORLD MAY 1984 CRAB gae am mA m a emg fe Bh G g bees canh e d Semiconductor technology siderable advantage of hindsight has advanced and costs have for most of the period that the dropped at about the rate pre total will be 17 million units cost dicted Expectations for bubble ing 79kM 79 billion dollars memories and holographic sto rage have not materialised The mismatch between the informa The delay factor tion processing capacity of the eye brain and the amount pro Forecasters are often misled by vided by the c r t screenful is manufacturers announcements being improved Larger display abbut development work which devices will be available rather may or may not be followed by sooner than predicted Teletextis production limited application successful but Viewdata Prestel and more general applicati
138. 6 programmable 1 0 lines spare socket for extra 4 K EPROM or 2 K RAM seven segment LED display cassette recorder interface ME breadboard iwre wrap A area system bus connector LO lines connector Option LS Projec tion manu C DC adaptor A collection of 15 programming and interfacing projects with construc and components Projects include music generator memory expan sion lO expansion game AD DA conversion optical senser real time clock EPROM programmer home and industrial applications No soldering or wire wrapping is required Price LS6S02 Z80 8085 Module work on Les LS Projects with components 109 00 109 00 129 00 109 00 5559 0 25 00 Fhe prices shown include surface marl postage 90 days warranty Cheques to Room 1 320 Quadrant House Sutton SM2 SAS Gt Britain Distributors Invited BINARY SYSTEM MAXWELL ROAD P O BOX 1583 REPUBLIC OF SINGAPORE CIRCLE 065 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanracdiohistorv com INGAPORE 9031 NEW PRODUCTS CIRCUIT BOARD REPAIR The salvage of just one complex p c b assembly would pay for the repair kit used to do it say OK Industries Available in economy standard and de luxe versions the kit includes repair tracks in most of the configurations likely to be required as well as setting tools Additional to the standard kit are a number of consumables epoxy resin flux cleaner spa
139. 669911 CIRCLE 081 FOR FURTHER DETAILS TEST EQUIPMENT Marconi TF2002B AM FM Signal Generator with TF2170 Synchroniser Tektronix 106 FastRise Pulse Generator Tektronix 191 Constant Amplitude Generator Tektronix T922R rack mounted dual channel 15mH2 oscilloscope Tektronix 2901 Time Mark Generator Tektronix 184 Time Mark Generator Tektronix MR501 X Y Monitor for TM500 system Tektronix 067 502 Amplitude Calibrator Tektronix 067 502 01 Amplitude Calibrator Tektronix DF2 Formatter for Logic Analysers Telequipment DM64 10MHz Storage Oscilloscope Gould Brush 500 X Y Plotter Marconi TF2401 50Mhz Counter Dana 5000 6 Digit Multimeter Hewlett Packard 8002B 10Mhz Pulse Generator Tecktronix 613 Storage Monitor Solartron 7201 Locator Singnature Analyser DMM Thermometer and Logic Analyser Siemens D2072 W2072 100Mhz Level Measuring System T Siemens D2006 W2006 17Mhz Level Measuring system Siemens G2022 Sweep Oscillator various plug ins available AVOModel 8 Mk 3 amp 4 AVO Model 7 7X amp Mk 2 Fluke 8020A DMM Unused Cases for above New J J Lloyd PL100 X Y Plotter DEC PDP 8 Computer DEC PDP 81 Computer in rack with reader etc Honeywell 20MByte Disk Drive with interface Sullivan AC Test Sets Philips PM 2522A Digital Multimeter Hewlett Packard 1801A Vertical Plug in Hewlett Packard 1821A Timebase Plugin Ice Digital
140. 7 7428 043 7473 93g 74109 073 74148 1 0 74190 190 TBA673 220 B7G unskirted 0 25 2BP 9 00 SEPISA 15 00 74110 0 51 74147 2 7 700 7404 0 18 7430 07 7474 0 38 411 j 2 00 74191 1 90 TBAT 1 52 BiGskned 035 3BD BM sup 2500 7405 018 7432 030 7475 654 74111 071 74148 1 76 73192 1 0 TBA720Q 2 30 BOA unskirtedi 2s EC 3 00 DG7s 63 32 7406 043 743 0 40 7476 0 42 74116 1 85 74150 1 80 74193 1 90 TBA750Q 2 07 B9A skirted 0 35 1 19 DG7 31 58 07 Tube Bases 1407 0 43 7437 0 32 7480 0 56 74118 1 00 74151 0 94 74194 1 25 DIBASOQ 1 20 prt Octal 038 SEDI op DG7 32 58 07 Priceson 7408 020 7438 032 7482 075 73009 154 74MM L80 74195 1 20 TBAW20 2 90 Loctal 955 3 T 90 DG7 36 65 00 application 7409 020 7440 032 7483 100 74120 0 83 74155 0 90 74196 1 35 TBA920Q 2 90 Nuvistor base 2 00 3J DH3 91 56 83 7410 017 7441 0 90 7484 105 74121 0 43 74156 0 90 74197 1 35 IBA990Q 2 90 8 pin DIL Texas 0 10 m ae DH7 11 113 12 742 029 7442 0 72 7486 0 39 74122 0 62 74157 0 5 74198 1 70 TCA270Q 2 90 14 pin DIL Texas 0 10 3JI 19 VCR97 12 00 B 0 32 7447AN 1 17 7490 00 73123 118 74159 220 74199 230 TCa760 1 38 16 pin DIL Texas 0 10 3KP1 15 00 VCRI38 12 00 7416 0 32 7450 0 18 7491 0 82 74125 0 58 74170 2 40 TAAS70 2 30 i Valve screening M OD VCRISA 12 50 747 932 745 018 7492 060 74126 0 588 74172 440 TAA amp NS
141. 75 2 50 EM84 200 M816 9 35 PL8IA 2 00 TY4 500 98 35 1B35A 48 00 6AS7G 8 75 6SA7 3 00 90C1 6 00 6159B 19 00 DK92 2 00 210 EM85 2 75 M8162 10 40 PL82 1 50 TYS S00 201 50 B63 64 00 6AT6 1 5 6SC7 235 90CG 14 54 6189 9 50 DK 1 75 2 00 EM87 2 50 M8163 8 25 PL83 2 50 TY6 800 196 50 1R5 1 75 6AUSGT 5 00 6SF7 2 50 90CV 15 45 6201 11 40 DL92 2 00 8 93 EN32 17 46 M8190 5 00 PL84 2 00 TY6 5000A 185 1 75 6AUG 2 50 6SH7 3 00 92AG 12 96 6442 20 00 DL94 1 75 ECC189 2 10 EN91 7 05 M8195 10 85 PLSO4S 2 50 490 00 1T4 1 75 6AVSGA 4 50 6SJ7 3 25 92AV 12 96 6883B 8 25 DL96 1 75 ECC807 175 EN9 6 96 M8196 7 50 PL508 2 50 TY6 5000B 2AS15 1150 6AV6 150 6SK7 3 50 95A 845 6973 4 00 DLSIO 14 00 ECC808 3 00 EY51 2 75 M8204 7 05 PL509 6 00 395 00 2 C39A 60 00 6AXSGT 3 00 6SK7GT 3 00 15082 6 50 7025 3 00 DLSIS 12 50 ECF80 2 55 EY8I 150 M8212 11 37 PLS19 6 00 TY6 5000W 2C43 70 00 6B7 3 25 6SN7GT 3 00 150B3 8 35 7551 6 25 DLSI6 12 50 ECF82 1 50 EY83 150 M8223 6 00 PL80 1 50 407 00 2D21 3 25 6B8 325 esQ7 3 40 150C2 3 25 7586 12 09 DLSI9 12 50 ECF86 2 50 EY84 9 24 M8224 6 30 PL802 6 00 TY7 6000A 2E26 8 25 6BA6 1 50 6SR7 4 00 150C4 6 00 7587 18 50 DM70 2 00 ECH35 3 00 EY86 1 75 M8225 4 50 PY33 2 50 485 00 2 42 98 00 6BA7 5 00 6557 275 2M 35 00 7609 56 00 DM71 2 00 ECH42 3 50 EY88 1 75 M8248 14 93 PY8I 1 50 TY7 6000X 2455 175 00 6BA8A 4 00 6U5G 3
142. 76 160p 4 way 30P 200mw 9p 74265 74L8283 80p 4018 75p 4C928 6 BFR39 32p TIP30A 35p 2N2484 30p 25C2335 200p Bway 120p iw 155 74273 7ALS290 80p 4019 60p 72168 22 DL704 140p BFR40 1 32p TIP30C 40p 2N2645 50p ES 200p 6 way 105p 74276 74 8282 900p 4020 gop ZN1040 670p 0t707 Fed 140p BFR79 32p TIP31A 40p 2N2904 5 30p 3N128 200p 10 way 150p WW 5 PLEASE ADD 50p p amp p amp 15 VAT Tecunomatic Lrp CY RER MAIL ORDERS TO 17 BURNLEY ROAD LONDON NW10 1ED Orders from Government Depts amp Colleges etc welcome SHOPS AT 17 BURNLEY ROAD LONDON NW10 AS Tel 01 452 1500 01 450 6597 Telex 922800 GC cru annie 305 EDGWARE ROAD LONDON W2 WIRELESS WORLD MAY 1984 87 WWW americanradiohistorv com CABLE T V HEAD END AND REPEATER AMPLIFIERS SINGLE CHANNEL AUTOMATIC GAIN CONTROL AMPLIFIERS TAG4863 Gain 48dB maximum output 63dBmV Regulator or 8dB Power requirement 14V 210mA TAG4063 Gain 40dB maximum output 64dBmV Regulator or 16dB Power requirement 14V 210mA SINGLE CHANNEL AMPLIFIERS TSS4663 Gain 28 46dB adjustable Maximum output 63dBmV Power requirement 14V 170mA TSS3062 Gan Z Dd adjustable Maximum output 62dBmV Power requirement 6mA DRIVER AMPLIFIERS TS1030FM FM driver amplifier 10dB Gain Maximum output 30dBmV Power require ment 14V 10mA TS1030B3 Band li driver amplfier 10dB gain Maximum output 30dBmV Power requirement 14V 10mA TS103
143. 80 EF8 175 Gusi 2000 OD3 2150 Qy36s 59 86 UF4l 2 00 42504 80 00 6CG7 2 50 12AX7 15 9 00 VALVES 10 50 EF86 175 GXUI 1535 OZ4 350 Gy3 125 6650 UF42 2 10 4A 8700 6CH6 13 00 12AY7A 400 3 00 10 00 EF89 150 GXU2 30 00 PC86 250 Qv42so 68 00 UF80 1 75 4gi 20 00 6CL6 3 75 12B4A 3 50 4 45 A1834 9 00 13 25 EF91 2 95 GXU3 2540 PC88 2 50 QY4 400 74 20 UF85 1 75 4C35 78 00 6CW4 8 00 12BA6 2 50 670 4 50 A2087 13 50 11 50 EF92 6 37 GXU4 44 50 PC9S 1 75 OY5 500 175 00 UF89 2 00 4CX250B 45 00 6D2 1 50 12BE6 2 50 5675 28 00 A2134 17 50 8 91 EF93 1 50 GXUSO 20 00 PC97 1 75 QY5 3000A ULAI 3 50 ACX3580A 73 00 6DK6 3 00 12BH7 2 75 5687 6 00 A2293 16 00 22 51 EF94 2 50 GY501 3 00 PC900 1 75 420 00 UL84 1 75 4XIS0A 60 00 6DQ6B 475 12BY7 3 00 5696 4 50 A2426 27 50 12 00 EF95 5 99 GZ32 4 00 PCC84 1 50 QZ06 20 32 70 UMSO 2 00 4XISOD 56 00 6EA8 3 00 WEI 20 00 5718 7 50 A2521 25 00 17 50 EF98 2 00 GZ33 4 75 PCC85 1 50 RIO 6 00 UY4l 2 25 SB254M 35 00 6EBS 2 50 WELTY 28 00 5725 5 50 A2900 15 00 32 25 EF183 2 00 GZ34 3 00 PCC88 2 00 R17 3 00 UY85 2 25 SB255M 35 00 GEW6 2 25 12E14 65 00 5726 11 37 A343 45 00 2 50 EFI84 2100 GZ37 4 75 PCC89 175 RIS 3 00 VLS631 15 00 5C22 160 00 6F6 3 00 BEI 170 00 5727 7 05 AZ31 2 75 1 25 EF804S 12 00 KT61 5 00 PCCIS9 2 50 R19 9 24 XG1 2500 5 00 SJ180E 1650 00 6F23 1 60 19H4 27 50 5749 2 50 AZ41 2 60 3 50 EF805S 15 00 KT66 12 00 PCC805 1 60 R20
144. 80 Specially designed for working with up to 40 pin ICs perfect for 3 amp 14 pin ICs Has 270 contact points including two 20 point bus bars 3 EXP 300 6 50 The most widely bought breadboard in the UK With 550 contact points two 40 point bus bars the EXP 300 will accept any size IC and up to 6 x 14 pin DIPS Use this breadboard with Adventures in Microelectronics 4 EXP 600 7 95 Most MICROPROCESSOR projects in magazines and educational books are built on the EXP O Clip the coupon and get your FREE project sheet with each EXP 300 bought AND a free catalogue Just ask about our other free projects too 5 EXP 650 4 75 Has 6 centre spacing so is perfect for MICROPROCESSOR applications 6 EXP 4B 2 75 Four more bus bars in snap on unit i jo Uc ULES WES mr a mE cSUQLD C x nisu du uer E MU T NEUE ROI Dim ER S RD Soe ER Fasc UK Limited Dept 7J8 Unit1 Shire Hill Industrial Estate Saffron Walden Essex CB11 3AQ a p Price include P amp P and 1596 VAT 1 send for our free catalogue FD I l h erv T erv T4 len fen J jar Ts erv us g el f iP GLOBAL SPECIALTIES CORPORATION _ 3 45 t523 8 63 j 10 29 6 33 4 03 14 95 2007 Name Address I l i enclose Cheque P O for amp SSCS or debit my Barclaycard Access American Express card no expiry date I G S C UK Ltd Dept 7J8 FOR IMMEDIATE ACTION The G S C 24 hour 5 day
145. 808 950p 47642 450P AM26LS31 WD1691 1500p 6 0 150p P 7418490 130p 80p CA3240E 120p 350p TDA2003 325p ETJ 318415 500p 160p WD2143 800p 6144 175p 36P 7 S540 120p 90p CA3280G 225p 350p TDA2004 300p 4416 15 500P AM26LS32 70 150 36P 34LS541 150p 90p D7002 600p 350p TDA2006 350p Mip i i w ij 4532 20 250p 160p 2168 175p J P 7aLS608 700p 4056 100p DACOBOC 200p 110p TOA2020 320p 5 7 2 4816AP 3 475p D7002 600p CHARACTER MEN 155 36P 7315610 1900p 4059 450p DACOBOR 200p 230p IDA2030 250p 265 12 5101 300P pacso 28 KASGA sac 1755 70p aop 5612 1200P 4060 30p DG308 300p 500p TDA2541 400p 3242 800P 5516 100p DMg131 275p TOS VER 7445 90p DER Sep 74LS626 180p 4063 930p HA1366 190p 200p TDA3560 390p ES 1500 8nePs 650p DP8304 300p ROS 2513 e loa sob 7446A 90p 7 P 74LS628 180p 4066 45p HA 388 250p 400p TOA7000 350p 2 16L P DS369 350 10 70 200 7447A S0p 74LS32 POA100p 3 4067 290p iCL7 06 700p 150p TLOG CP 5op 6522 350p 6264 15 35 5 PEG 700p p 7448 Sop 74L833 36p 74L8629 180p 108 p 1 TLOG2 75p 6522A 550p 6514 45 300p 988830 140p DMgesca 12 119 300p M50 3p 741837 asp Tat S810 iib 400 30n ICLIGSO atop op Tlosa 100p 932 S50 6810 ago paas Jop MC66760 750p 22 Wo 451 0 p 2 a en 1 ms Mas ne tupu poean degre Ee Mose gm mon es feb nese ee DRS um DOT Dur Ue 2454 30p 74LS42 55p 74LS642 1300p 407 30p ICM72 68 2400p
146. 83 0 10 8D238 040 BFR9 175 TIPA2C 0 47 HANDHELD f 20 MHz DUAL TRACE AC128 0 28 BC183L_ 0 09 BD241 040 BFT42 0 28 TIP47 0 65 i 6 30 150W DT420 AC128K 0 32 BC184L8 0 09 8D242 0 50 BFT43 0 28 TIP120 0 60 Auto range pol 35 models stocked AC141 0 28 8C204 0 10 80246 0 60 BFW92 0 85 TIP125 0 65 g KD200 FS800 ACI41K 0 34 BC207B 0 13 8D376 0 32 BFX29 0 30 TIP142 125 AC142K 0 30 BC208B 0 13 BD410 0 55 BFX84 0 26 TIP146 2 75 25 15 VAT 99 15 VAT 1 99 15 VAT AC176 0 22 BC212 0 09 BD434 055 BFX85 0 32 TIP161 2 95 1 postage 3 postage 5 Securicor AC176K 031 BC212L 0 09 BD437 0 50 BFX86 0 30 TIP2955 080 wa t 3 a mS EUIS ee OU m s 8C213 0 S M HOUSE TOTTON SOUTHAMPTON SO4 4DP ENGLAND ACIBB 025 Berit up go us e a21 nue Ma s BC214 0 j Tel SOUTHAMPTON 44 0 703 867333 Telex 477351 SMCOMM G AD142 079 8C2i4C 0 oS BD538 0 65 BFY3S0 077 2N2905 040 AD143 0 82 BC214L 0 09 80597 0 75 BLY4B 175 2N3053 0 40 EUST g 3 z AD149 0 70 BC2378 0 09 BD697 110 BR100 026 2N3054 0 59 CIRCLE 056 FOR FURTHER DETAILS ADI61 0 39 BC238 0 09 BD698 1170 B8R10 0 49 2N3055 0 52 AD162 0 39 8C239 0 12 80707 0 80 BRC4443 0 85 2N3702 0 12 AD161 2 0 90 BC251A 0 12 BDX32 150 BT100A 02 2N3703 012 AF114 150 BC252A 015 BDY57 1 65 0 75 2N3704 0 12 AF124 0 65 BC258 0 25 BFI15 0 35 BT106 149 2N3705 0 12 AF125 0 35 BC258A 0 39 BF119 0 65 BT116 120 2N
147. 93 9 75 p rgo2 oso R1169 55 00 VLS63 1095 382 3 00 6BL7GTA 3 95 7A7 200 85a1 650 7475 5 00 E288CC 13 50 Efisa oes HF94 150 pcreos 125 RGI 125 4 95 VP4B 450 387 450 GBR 065 75D 75 aao fuso 2561 5 75 EBI0F 1850 trig oes HK90 1 05 pcrpgoe 100 RG1 240A VP133 2 00 3826 24 00 6BRS 970 787 250 goav 1000 7558 1150 E1148 100 F739 tgo HL2K 3 60 PCF8o8 125 1450 VR75 30 3 00 3828 12 00 6BR7 495 7C5 3 00 goci 270 7886 1180 E1524 6 95 gp73 350 HL2300 4 00 pcu200 150 RG3 250A 350 VRIO 200 3C4 100 68R8 2 15 7C6 250 99 G 1350 7587 2635 EAS50 100 6732 350 HL4 3550 p ls ogs RG3 1250A VR105 30 150 3C45 2400 6BRBA 215 7J7 350 giAG 39 00 J591A 550 EA76 19 EF800 1100 HL41DD 3 50 PCLB3 250 52 50 VR150 30 1 15 3CN3A 250 6BS7 5 50 7Q7 2 00 92AG 12 50 7609 47 00 EA 195 Eggoss 1350 HL42DD 3 50 PCL84 o 85 RK2K25 62 50 VT52 250 3CS6 0 95 68S8 250 IV 45 92AV 12 50 7868 3 95 T T s 8012 15 00 8042 4500 WIREWOUND RESISTORS BASES ETC ZENER DIODES W E 8136 1 00 7 CALLERS 8245 107 50 PREFERRED VALUES EM e s BZX61 0 15 8298A 495 1 Aes Ou LEES GOL 20V IN AN INV INN M ee oe Med MEE B8G 0 70 4 Watt sox oza BSA 020 33V 36V 39V 47V 51V 56V 68V 76V 50 YDS SOUTH OF MEOPHAM GREEN TA B9A Skirted 8045 10 00 R47 4K7 0 18 BZY88 0 07 1 5k6 2Kk 019 mos S 27 3V 3V3 3V6 3V9 4V3 4V7 SVI CAR PARKING AVAILABLE 5V6 6V2 6
148. AC tK to 10 Meg ohm MX430 32 ranges 40K Volt 0C 4K V AC 1OmV to 1500V DC 5V to 1500V AC 25uA to 15A OC 1 4uA to 15A AC 50 ohm and 500 ohm linear scale Direct meter reading LHMB80A 0 40KV AC CLAMPMETER 0 3004 0 600V AC 0 1K ohm Tota 9 ranges with carry case and leads ST300 26 D4 UK C P 65p xc Shop I4 65 00 59 00 ST303TR 22 range 20K Volt plus Hte tester 23 00 1 Meg oh KHP3ON 0 30 0 45K V tt c en hart al UK C P elther model 1 00 7 M M i HC6015 15 range pocket 10K Velt 1 meg ohm 7 M200 30 range 20K Volt 20KHZ Special purchase 8 65 list price 19 00 HM102BZ 22 range 20K Volt 10A 2C plus cont Buzzar 10 1 ohm 11 74 TM K500 23 range bench 30K Volt 12A OC Plus cont buzzer 20 Meg ohm 20 83 MHS6R 22 range 10K Volt 6 Meg onm 10 39 830A x 26 range 30K Volt 10AC 0C 10 Meg ohm 20 83 360TR x 23 range bench 100K Volt large scale 10A AC OC plus Hie tester 10 Meg ohm 34 74 AT2100 31 range de luxe 100K Volt 10A AC OC 100 Meg ohm 29 13 AT1020 18 range de luxe 20K Volt plus Hie tester 5 Meg ohm i K ohm and 20 Meg ohm 89 00 NilsoeT Re 18 range 20K Volt plus Hfe EN M Hiee ohm 12 1 HIGH VOLTAGE METERS KR 1 Range doubler 35 range tatal 17 35 15 81 50K Volt 10A OC 20 Meg ohm ELECTRONIC INSULATION TESTER 500V 0 100 Meg ohm with carry csse
149. ACB Artwerk 48 Westbourne T TT Sveaharn Worce Wt GFT DESIGN SERVICES Electro design de velopment and production service available for digital and analogue instruments RF Transmit ters and receivers telemetery and con rol systems 20 vears experience R C S Electromes Wolsey Road Ashford Middlesex Phone Mr Falkner 53661 8341 board assemblies WWW americanradiohistorv com FOR THE BEST PCB SERVICE AVAILABLE Circuit Design amp Development Digital and Analogue Artwork Layout Work of the highest standard by experienced draughtsmen No minimum charge Board Manufacture Prototype to sem production excellent rates 24 hour prototype service from filmwork Wiring amp Assembly PCB assembly wiring and cable forming by qualified staff Test Full test facilities available One or all services avail able no order too small Please telephone Chelms ford 0245 357935 or write to HCR Electronics The In dustrial Unit Parker Road Chelmsford 1169 ELECTRONIC SERVICES Design and de velopment Repair test PCB assembly Equip ment prototypes and production 14 years experience since 1970 Young Electronics Ltd Southgate London N14 Tel 01 886 6709 2451 PROFESSIONAL DESIGN SERVICE Ana logue RF circuit system design Specialising in microwave amplifier oscillator and network design MOTOROLA 6805 6809 series micropro sor design development capability All work c
150. AR PLUG IN CONSTRUCTION KEYPAD FUNCTIONS INDICATED BY DISPLAYS NOW AVAILABLE AT HIGHLY COMPETITIVE PRICES Send for Technical Brochure to Tel 0344 885656 Vigilant Communications Ltd Telex 849769 Vigcom G Unit 5 Pontiac Works Fernbank Road Ascot Berks SL5 8JH England CIRCLE 027 FOR FURTHER DETAILS WRONG TIME MSF CLOCK is ALWAYS CORRECT never gains or loses SELF SETTING at switch on 8 digits show Date Hours Minutes and Seconds 24 hour format larger digit Hours and Minutes for easy OUICK GLANCE time auto GMT BST and leap year can expand to Years Months Weekday and Milliseconds with parallel BCD output for computer and audio to record with commentary and show time on playback receives Rugby 60KHz atomic time signals only 15x5X8cm superhet receiver built in antenna 1000Km range GET the RIGHT TIME 72 70 Fun to build kit ready made to order includes all parts printed circuit case instructions by return postage etc list of all kits SEND away NOW CAMBRIDGE KITS 45 WE Old School Lane Milton Cambridge Tel 860150 SOLDER FUME ABSORBER Removes smoke and fumes from soldering area and absorbs harmful components using activated carbon filter Free standing unit adjustable for angle with removable hood Supplied with 3 spare filters Price only 58 04 Light Soldering Developments Ltd 97 99 Gloucester Road Croydon CRO 2DN 01 689 0574 CIRCLE 045 FOR FURT
151. Associates Limited International Recruitment Consultants 45 Kensington High Street London W8 SED W Webb Whitley Associates Ltd partners in progress WWW americanradiohistorv com Appointments MAXELL UK LTD SALES ENGINEER FOR PROFESSIONAL AND INDUSTRIAL VIDEO PRODUCTS Maxell UK Ltd is a subsidiary of one of the world s lar gest and most respected tape companies Maxell s research and development efforts have brought very high performance tapes to both the amateur and professional user and to supply the European market for video tape Maxell have recently completed construction of a video tape factory in Telford Shropshire The company has achieved considerable success as a supplier to broadcast duplication and video facilities companies and to support these clients Maxell now wish to appoint a Sales Engineer The products mainly involved will be VHS Beta and U matic video cassettes and the position will involve sales and tech nical liaison with existing and potential users of these pro ducts The successful candidate will ideally be educated to degree standard and have experience in consumer and professional video systems The company offers a secure future in an industry which is developing rapidly and which will present an inter esting and challenging working environment The position is based in Harrow Middlesex and benef its include free membership of the company BUPA scheme and a company car If this po
152. B ASBSS ANN case sevice many internal controls for The amazing SOFTY 2 The Complete Toolkit A massive purchase of these desk top TERMINALS N linearity etc The monitor accepts standard for writing copying modifying and listing printer terminals enables us to offer you I 0 ie wp 75 ohm composite video signal via SO239 9 FROM E195 CAR VAT EPROMS of the2516 2716 2532 2732 these quality 30 cps printers at a SUPER socket on rear panel Bandwidth of the unit range Many other functions include integral LOW PRIC against their original cost of Fully fledged industry standard ASR33 data ll is estimated around 20 Mhz and will display keyboard cassette interface seria and parallel Over 1000 Unit comprises ol full QWERTY terminai any features including ASCII most high def graphics and 132 x 24 lines data i o UHF modulator electronic keyboard and printer mech with keyboard and printer for data I O auto data Units are secondhand and may have screen ONLY 169 00 PP 2 50 print face similar to correspondence quality detect circuitry RS232 serial interface 110 lE burns However where burns exist they are NEW GANG OF EIGHT intelligent Z80 Type wiiorvarable dos unit cin baud 8 bit paper tape punch and reader for oniy apparent when monitor is switched off controlled gang bang programmer for ALL paper upper lower PASA Standard S232 fp O line data preparation and ndiculously Although unguaranteed ali monitors are single 5V rai
153. BATTERY Display 3v Digit 13mm LCD Dept A Cottrell House 53 63 Wembley Hill Road O load Protection All ranges Z N Wembley Middlesex HA9 8BH BATTERY AND TEST LEADS X Telephone 01 902 4321 3 lines TELEX No 923985 Please add 15 to your order for VAT P amp P free of charge Payment by cheque ra ES with order Offer applicable to mainland UK only awe SPECIFICATION HC1015 ANALOGUE DC Voltage 0 25 2 5 25 250 1 000 Volts 10 000 Ohms Volt AC Voltage 10 50 250 1 000 Volts 4 000 Ohms Volt DC Current 1 10 500mA Resistance 0 to 1 MegOhm in 3 ranges Decibels 20dB to 62dB Battery One 1 5V size AA incl 2 ARMON ELECTRONICS LTD Sie amp Weight 105 x 63 x 32mm 130gr 19 RANGES COMPLETE WITH amp TEST LEADS INCLUDED TRADE ENQUIRIES INVITED FULL RANGE OF METERS ON APPLICATION Please allow 15 days for delivery CIRCLE 035 FOR FURTHER DETAILS Lynwood GD1 VDUs Intelligent Green micro controlled RS232 printer port 101 key k b Full Video enhancements ONLY 149 15 P amp P S H Burroughs MT686 7 TD710 Intelligent Green 12 VDU with 3 micros and 64K store RS232 Programmable Only 199 new or 149 S H 15 P amp P Videocom Apollo VDUs Stylish 15 Green Z80 controlled VDU with printer port and lots of very ad vanced features Only 399 new or 249 S H 15 P amp P Centronics 306 Line printers Professional fast 120 cps superb quality 80 column pri
154. BC COMPATIBLE DISC DRIVES AS B Econet 389 Please phone for availability B DFS 429 These drives are supplied with manual form disc and B DFS Econet 470 cables Carriage 7 Single Drive 100k 140 200k 1757 400k 195 BBC Ultracale 65 Toolkit 20 EXMON 20 DISC DOCTOR 30 FX Dump 15 Graphics ROM 28 Termi ROM 29 Software from ACORNSOFT PROGRAM POWER GEMINI in stock Model A to Model B Single Drive with PSU 100k 165 200k 210 400k 221 Dua Drive with PSU 2 x 100k 320 2 x 200k 400 Upgrade Kit 95 2 x 400k 420 Installation 15 These drives are switchable between 40 80 tracks LANGUAGE ROMs 40 80 Switch Module for x 400k and 2 x 400k Drive BCPL ROM Disc 32 Manual 87 DISKETTES In packs of 10 W Wabash M 3M UTILITY ROMs 40T SSSD W 14 M 16 40T DSDD M 22 80T SSDD W 24 M 26 80T DSDD W 26 M 30 Carriage 2 box FLOPPICLENE Drive Head Cleaning Kit 14 50 CASSETTE RECORDERS SANYO DR101 Data Recorder 34 2 50 car riage BBC Tape Recorder 28 50 2 50 carriage Cassette Lead 3 1 carriage HOBBIT Fioppy Tale 135 2 50 carriage HOBBIT Zero Memory Option 25 1 car nage Computer Grade C12 cassette 50p each 4 50 for 10 1 carriage MONITORS MICROVITEC 1431P 14 RGB PAL Std Res 249 MICROVITEC 1451 14 RGB Med Res 299 MICROVITEC 1441 14 RGB Hi Res 420 MICROVITE
155. C Activating X sets bistable IC which was reset when the internal clear key was pressed through IC 19 y to enable the hexadecimal keypad decoder IC so that digits entered are stored in IC sequentially On entry of each digit monostable IC generates a pulse which decrements counter IC by one Following entry of the four digit combination the borrow output of IC goes low and disables IC inhibiting further entry of digits into encoders IC Keyboard activation is indicated by the l e d Activating X connects clock MCK to clock inputs of shift registers IC 9 causing the internal keyword to be transferred serially through the Q output of IC to one of the inputs of the exclusive Or circuit comprising IC o 29 jo Also activating X will put shift registers IC in shift mode due to ICyo g outputs and connect clock MCK to inputs of both registers causing the entered keyword to be shifted in WWW americanradiohistorv com synchronism with the internal keyword to the second input of the exclusive Or circuit This permits a comparison which if untrue sends the error line high Note that MCK is 4n times the CK clock frequency where n is the number of codeword digits Ifthe comparison is true IC i will be cleared and with the activation of X the open line will go high and open the lock Otherwise IC will be set on the first low to high transition of Error setting IC and
156. C 2031 20 RGB Std Res 287 KAGA VISION 12 RGB Std Res 230 KAGA VISION II 127 RGB Hi Res 260 KAGA VISION II 12 RGB Super Hi Res 358 KAGA 12 GREEN Hi Res 106 SANYO DM8112CX 12 Green Hi Res 99 Allleads included Carriage 7 TORCH Z80 DISC PACK Your BBC computer can be converted into a business machine with the addition of a TORCH Z80 disc pack the Torch pack with twin disc drive and the Z80 processor card greatly enhances the computer s data storage and processing capability Z80 card comes complete with 64K RAM and a CP M compatible operating system In addition to BBC owner s user guide and a systems disc the package is supplied with PERFECT software pack age comprising of DATABASE WORD PROCESSOR amp SPREAD SHEET Complete Package for 730 8 carr PRINTERS amp PLOTTERS i EPSON FX80 350 EPSON RX80 FT 250 EPSON FX 100 450 SEIKOSHA GP 100A 160 JUKI 6100 Daisy Wheel 350 MCP 40 Col Printer Plotter 120 Colour Graphics Plotter A3 size 270 GRAFPAD Graphics Tablet 125 Carriage 7 ACCESSORIES Parallel Printer Lead 10 1 carriage Serial Printer Lead 8 1 carriage Epson Serial Interface 2K 60 1 carriage Epson Serial interface 50 1 carriage NEC Serial Interface 42 1 50 carriage Epson Paper Roli Holder 17 1 50 car TIME WARP BBC REAL TIME CLOCK CALENDAR A low cost unit that opens up the total range of Real Time applications With i
157. COMMONSIDE EAST MITCHAM 1391 CAPACITY AVAILABLE PCB ELECTRONIC ASSEMBLY Circuit Design amp Development Prototyping Pre production Consultancy Full Production Capability Component Sourcing amp Stocking Complete Test Facilities STAGECRAFT ELECTRONICS LTD 3 Churchfield Road Acton Central W3 6BH Tel 01 993 1852 3660 2203 FREE PROTOTYPE of the finest quality with EVERY P C B artwork designed by us Compe titive hourly rates and high standard of work Halstead Designs Limited Tel Halstead 0787 477408 2126 LASSIFIED ADVERTISEMENTS Use this Form for your Sales and Wants PLEASE INSERT THE ADVERTISEMENT INDICATED ON FORM BELOW To Wireless World Classified Advertisement Dept Quadrant House The Quadrant Sutton Surrey SM2 5AS Rate 3 50 PER LINE Average six words per line Minimum 25 prepayable Name and address to be included in charge if TW ELECTRONICS LTD THE PCB ASSEMBLERS More and more companies are investi gating the advantages of using a profes sional subcontractor Such an undertak ing requires certain assurances TW are able to satisfy all of them quality competitive pricing firm delivey and close co operation with the cus tomer Assembled boards at 100 inspected before flow soldering and reinspected after automatic cropping and cleaning Every batch of completed boards is is sued with a signed certificate of confor mity and q
158. Capstan Variable capstan input Fig 9 Circuit arrangement at a shows feedforward signal predicting slope of bimorph drive derived from capstan speed deviation At b correct choice of dither frequency enables interleaving of tracking error spectrum and smapling 58 1X speed reference SIGNAL ENERGY e EN PU j field field Up Bimorph drive Down Bimorph drive Down 12345 678 9D TN 2 13 NT Ne 45678 9107 5 3X 2 track forward jump every field plays every third tape field t Y Nt 1X 2 track reverse jump every field plays fields in reverse 2 track forward 3 Note jump symmetry of 3 and 1 2 track waveforms reverse 1 jump Reset Predicted slope every V pulse To summer in Figs 5 a Speed deviation zero at 1X Integrator a Comb filter response rejects sampling sidebands D 350 400 450 500 550 Dither frequency 425Hz 0 50 100 150 200 250 300 WWW americanradiohistorv com obtained The feedback system has now only to correct for differ ence between actual track posi tion and predicted track position and the tracking error will be independent of bimorph excur sion Figure 9 shows details ofthe system Stability criteria for a dither based servo warrant a closer study The tracking error is sam pled at the dither frequency by the phase sensitive rectifier s it is a sampl
159. Clearances between pads and tracks can be checked visually although an automatic clearance check is to be added to the system Individual tracks or groups oftracks are initially given straight line connections and may then be moved using a rubber band control Output from the system may beon a precision drafting plotter CONTROLLER FORTHE BBC MICRO A controller interface designed to plug into the 1MHz bus socket of the BBC computer provides a number of useful facilities including an eight channel eight bit a to d converter an eight bit input port eight bit output port four switch inputs four relay outputs and a bus extender for further expansion The a to d converter is a single chip device with a separate 2 45V precision voltage reference 1 c it gives 256 step resolution on all eight channels A 5V regulator provides the supply for all the internal circuitry with a spare capacity of 80mA for external circuitry Up to four switches can be connected directly to the switch inputs and the four internal relays can be used to switch devices of up to 12V at 1A They could also be used to switch external relays for higher power requirements The expansion connector uses its own configuration for add ons designed by the makers There is already an additional a to d pack which allows for high speed operation it takes 100K samples s and is said to be ideal for use with an experimental digital storage oscill
160. DCASTING AUTHORITIES MIXING DESK MANUFACTURERS RECORDING STUDIOS HI FI ENTHUSIASTS BAND GROUPS AND PUBLIC ADORESS FIRMS Export is a speciality and we have overseas clients in the COMMONWEALTH E E C USA MIDDLE EAST atc Send for our questionnaire which when completed enables us to post quota tions by return E A Sowter Ltd Manufacturers and Designers E A SOWTER LTD Established 1941 Reg No England 303990 The Boat T Cullingham Road ipswich IP1 2EG Suffolk P O Box 36 ipswich 1P7 2EL England Phone 0473 52794 and 0473 219390 Telex 987703G Sowter CIRCLE 008 FOR FURTHER DETAILS OUR INK JET PRINTER Logic seeking in dot address mode 132 Column Compressed Mode pe 499 VAT Centronics parallel interface with full Viewdata and free BBC Micro dump listing also prints OVERHEAD TRANSPARENCIES Options available Buffered RS232 Viewdata interface Apple II amp Ile interface IBM pc dump Specifications 1280 dots line in double res mode 37cps in full colour Friction feed roll paper and single sheet feed A4 Ink cartridges 4 million character life Portwood Industrial Estate Church Gresley Burton on Trent Staffs DE11 9PT Burton on Trent 0283 215432 Telex 377106 j VELLEMAN KITS High quality range of electronic kits for serious amateurs qualified engineers and training schools and colleges NEW INTERFACE SYSTEM FOR SINCLAIR ZX81 and SPECTRUM COMPUTERS
161. DM801 700KHZ to 250MHZ Dip meter inductive cap res Ireg measurement elc 62 00 CHART RECORDER 100mV 2mA Panel mount 240V AC 149 00 LFM39 A O Wow and flutter meter Jis CCIR Din 445 00 HZ65 Scope add on component tester 24 00 LTC910A CRT tester rejuvenator for b w and colour 175 00 eco usus NEMR BE lk s RETAIL MAIL ORDER EXPORT INDUSTRIAL EDUCATIONAL RY S 404 406 Edgware Road London W2 Computers 01 402 6822 Equipment 01 724 0323 e Components 01 723 1008 Shop AUDIO ELECTRONICS 301 Edgware Road London W2 Official orders welcome Subject to confir mation Buy d xh Acres Reus 7 CROTECH EDUCATIONAL Full specitication any model Send SAE UK C P amp ins Single trace carrier Dual trace 2 60 carrier TNT 5 20 TNT 7 00 Securicor 10 45 Securicor 13 00 2 years warranly HAMEG HM103 Single trace 10MHZ 2mV 6 x 7cm display plus component tesler 158 00 HM203 Dual trace 20MHZ 2mV Algebraic add Z Mod plus component lester Optional carry case 21 50 264 00 HM204 Quai trace 20MHZ sweep delay 2mV plus component tester optional carry E case 21 50 365 00 HM605 Qua trace BOMHZ delay line 1mV 1MHZ CALGEN optional carry case 21 50 487 00 HITACHI All models 5mV 1mV using x5 Th 1 magnifier Al models complele with 2 probes 2 years warranty V212 Dual 20MHZ bench portable 6 CRT CH 0 P 335 00 V222 Qua
162. ES CIRCLE 075 FOR FURTHER DETAILS BERG LOW PROFILE 14 PIN DUAL IN LINE C SOCKET manufactured from glass filled polyester to UL94V O 7 for 100 31 for 500 56 for 1 000 256 for 5 000 460 for 10 909 E2109 for 50 000 3 700 for 100 000 Sample 10 sent for 1 20 30p P amp P 1 inc BERG LOW PROFILE 16 PIN DUAL IN LINE I C SOCKET as above 8 for 100 36 for 500 65 for 1 000 295 for 5 000 350 for 10 000 2 390 for 50 000 4 300 for 100 000 Sample 10 sent for 1 40 30p P amp P 1 96 inc VAT WIRE CUTTER AND STRIPPER TEMPERED STEEL BLADES spring loaded with moulded red p v c handles Cutting and stripping adjustable up to 6mm Overall length 135mm weight 64grm 10 for 15 25 for 34 50 for 63 100 for 116 500 for 525 1 000 for 1 000 Sample pair sent for 1 75 25p P amp P 2 60 inc V A T HIGH POWER SILICON BRIDGE RECTIFIERS 25 amp 600v Single hole fixing 250 1 4in push on connector terminals manufactured by IR 20 tor 10 90 for 50 175 for 100 800 for 500 1 450 for 1 000 Special quotation for larger quantities Sample sent for 2 50 25p P amp P 316 inc VAT METAL FILM RESISTORS FZ4 Manufactured by C G S Semi precision with a standard tolerance of 2 and a temperature coefficient of better than 100 ppm oc We have a fuli range in stock from 100A to IMO All bandoliered 2 50 for 1 000 any one value WIRE WOUND RESISTORS Manufactured by E
163. EXT N GOTO 20 Run this then delete lines 40 to 70 40 50 60 70 LETQ PEEKP POKE 49152 Q NEXTN GOTO 20 Note Frequency may be reduced by inserting 55 PAUSE x where xis the pause value Pull up resistors 10 Square wave output 74 LS 10 27 amp 30 Pin7 Gnd 1h Vcc TLS 10 WWW americanradiohistorv com Fig 4 Measurement and signal generation interface for the ZX81 provides voltage period interval and frequency measurement accurate and programmable ulse squarewave signals and ow frequency synthesized waveforms through software Spare digitali o lines are available on the 8255 i c Analogue output O Analogue input X See timer counter connections fig 3 31 32 ZX81 INTERFACE nally decoded by both devices Input output port A of the 8255 supplies data to the d to a con verter and the converter output is connected to D of port C Coun ter one output of the 8253 is con nected to D of port C A 5V supply is available from the computer but using this can lead to problems It is better to use the 9V unregulated supply and a separate 5V regulator with a small heat sink The ZX81 trans former should cope with this pro vided that no other external loads are applied Each program shown will operate on its own using the standard 1K byte memory if fur ther memory is available all of the functions could be incorporated in one large program
164. F5 FM High Band 70 Tektronix Storage Display Unit Type 611 120 Solartron DVM Type 1420 2 65 Pye Europa Type MF5U UHF 70 Tektronix Oscilloscope Type 515A 85 Hewlett Packard Power Supply 0 40v 30amp Pye Olympic Type M201 AM High Band 65 Tektronix Plugin Type CA 25 Type 6268B 450 Pye Mototone Type M5 AM High Band amp Low Band 45 Schomandl Frequency Meter lype FD 1 30 900Mhz 50 P T Pye Westminster Type W30 Low Band 25 Rohde amp Schwarz AF Wave Analyzer Type BN48302 50 Se homed Modulator ype MAT DN PA 962 E Pye Pocketphone Type PF5 UHF Complete with Batterie 35 Rohde amp Schwarz UHF Test Receiver Type BN1523 280 940Mnz 75 enoolmand Syninesizeril ype Burndept UHF Portable Type BE 471 with manual 125 Airmec Modulation Meter Type 210 3 300Mhz 95 Rande Ao orhwarz Decade Signal ieneratot Marconi Carrier Deviation Meter Type TF 791D 4 1024Mhz 125 0 3 500 Mhz Type SMDV BN 41104 1200 ee h R x y Marconi FM Signal Generator Type TF 1066B 1 10 470Mhz 280 Rohde amp Schwarz Sweep Signal Generalor 50Kh l2Mhz lype WANTED Second Hand Radiolelephone Equipment Marconi AM Signal Generator Type TF 144H 4S 10Khz 72Mhz 125 8N4242 2 75 es Marconi Out of Limits Indicator Type TF 2404 60 Rohde amp Schwarz Power Signal Generalor0 1 30Mhz TypeBN41001 125 UCC Micro Film Reader Cassette lype 35 Rhode amp Schwarz Frequency Indicator Type BN47051 50 Pye Bantam Battery Chargers 10 Marconi Transmission Line Tes
165. For tunately attenuation of an optical fibre is much less than that of tra ditional coaxial cables resulting in potentially longer spacings 20 to 50 km where there are few cable splices or optical junctions The problem of restricted power budget must be kept in mind when considering optical fibres for data network systems where there may be many junctions couplers or splitters with attend ant high losses There is no opti cal equivalent of a high imped ance tap general comparison is made in Table 2 between the character istics of twisted pairs coaxial WWW americanradiohistorv com Table 2 Comparison of major communication cable TWISTED COAX OPTICAL PAIR CABLE FIBRE 1 2 50 100 1 000 5 000 1 2 1 2 5 20 Low Medium Highnow small small large increase increase decrease infuture infuture infuture 20 40 20 40 2 5 10 40 in future High Low Negligible Low Medium High No No Total High High Low Soldering Soldering Splicing standard standard well connectors connectors aligned connectors Loose Medium Precise cables and fibre optics used as communication links The many advantages ofa fibre optic link are clearly evident Main benefits of fibre optic systems over metal cables higher system channel capacity larger bandwidth and small loss longer distance between repeaters electrical isolation of input and output almost complete immun ity to e m i almost complete freedom from
166. HER DETAILS CIRCLE 017 FOR FURTHER DETAILS 92 WIRELESS WORLD MAY 1984 MICRO ENGRAVER MICROPROCESSOR CONTROLLED ENGRAVING MACHINE Low cost NC controllers for lathes amp machine tools Price From 1 500 STEPPING MOTOR XYZ MACHINE complete with microprocessor controller and software programmed to engrave alphabet and numbers Also features easy operator programmable XYZ sequences to engrave drill or cut out special shapes and logos XY axis travel 200 170mm Z 20mm Mixed character sizes on a label from 1 99mm high Qwerty keyboard 24 character liquid crystal display Machine supplied complete and ready to manufacture labels J A F GRAPHICS PRICE 2650 00 70 Leek Road Congleton Cheshire CW12 3HU 02602 5127 e e on A E i WWW americanradiohistorv com fete Erie wa es ue ppointments Advertisements accepted up to 12 noon Tuesday April 3 for May issue subject to space available PHONE IAN FAUX 01 661 3033 DIRECT LINE THE BEST 7 000 22 000 Where does your interest lie Graphics Comms Robotics Simulation Image and Signal Processing Medical Automation Avionics Acoustics Weapons Radar Opto and Laser Experienced in Microprocessor Hardware or Software Digital and Analogue circuitry RF and Microwave techniques There are hundreds of opportunities in Design Test Sales and Service for Engineers and Managers For free prof
167. Head for auto reverse or quadrophonic use Full specification record and playback head 9 73 LINSLEY HOOD 100 WATT MOSFET POWER AMPLIFIER The very latest amplifier design published in Wireless World by the renowned John Linsley Hood This may now be taken as the standard by which the rest are judged Our kit approved by the designer has massive heat sinks and power supply and includes all components needed to build Case size 442mm wide 254mm deep and 145mm high Automatic switched speaker protection is included as standard Cost of all parts is over 120 Our complete stereo kit price 105 50 SOLENOID CONTROLLED HI FI DIGITAL CASSETTE MECHANISM Three band LW MW FM Stereo Tuner fully assembled on PCB 165 x B5mm Supplied with Ferrite rod aerial and band switch fully wired Facility provided to drive tuning meter and stereo LED Only needs 12v DC supply FM sensitivity 2 5uV Price only 7 99 inc VAT and post COMPLETE STEREO TUNER MODULE HALF HEIGHT 54 FLOPPY DISK Please consult our list for technical data on these and other Special Purpose Heads HART TRIPLE PURPOSE TEST CASSETTE TC1 One inexpensive test cassette enables you to set up VU level head azimuth and tape speed invaluable when fitting new heads Only 4 66 plus VAT and 50p postage Tape Head De magnetiser Handy size mains operated unit prevents build up of residual head magnetisation causing noise on playback 4 54 Curved Pole Type
168. I SENSITIVE VVM TF2600 0Hz 1GMHz tmV 300V 75 150 250 150 Trace SOMHz 45 HP VHF SIG GEN 6080 10 420MHz CORDER 2305 sohd state B amp K LEVEL RECORDER 2305 valve B amp K MiCROPHONE AMPLIFIER 2603 B amp K RANDON NOISE GEN 1402 B amp K RMS AUDIO VOLTMETER 2410 B amp K MICROPHONE 4111 with stand and cable B amp K AUDIO FREQ SPECTROMETER 2109 with level re corder 2304 150 WAYNE KERR UNIVERSAL BRIDGE B221 Mk 3 meter indicator with low imp adaptor 022 Mk 3 175 WAYNE KERR UNIVERSAL BRIDGE B221 with low imp adaptor 0221 35 WAYNE KERR COMPONENT BRIDGE B521 45 WAYNE KERR VHF ADMITTANCE BRIDGE 8801 WAYNE KERR AF SIG GEN S121 10Hz 120kHz ADVANCE PULSE GENERATOR PG52B 125 40 350 ADVANCE QUAL STAB DC PS P P3 0 30V0 A twice Metered SOLARTRON OVM A223 AC DC Dhm 412 digit AVO MULTIMETER CT471A Ex Ministry AVO MULTIMETER 7X AVO MULTIMETER 8s from AVO TRANSISTOR TESTER TT169 with leads As new P amp P 2 20 AVO VALVE CHARACTERISTIC METER VCMI63 with data 250 AIRMEC MODULATION METER 210 3 300MHz AM FM BRANDENBURG POWER SUPPLY 374SEL 0 1000V 91 BRANDENBURG POWER SUPPLY PM2500 R 0 2 Skv 9 125 TAYLOR INSULATION TESTER 130C 500VMax P amp P 3 25 97 GREEN SYNTHESISED DIGITAL SIGNAL GENERATOR TG1800 1Hz 9 9MHz Sine Square 410 4n 412 413 414 375 380 381 383 387 390 392 398 Many tune 600 MARCONI SIG GEN TF2002B 10KHz 88MHz AM FM 50
169. IC or 1167B0 9 Pin connections TOA 2590 1 2 Siliconix VNO6IOL or 22220 d gs View 0n leads Top view A circuit board layout that will be available for the decoder design has a dual in line arrangement for the 796 i c Motorola s MC1496 or 1596 suffix G or Lis available from Ambit WIRELESS WORLD MAY 1984 SC84 Micro computer Designed for engineers and enthusiasts the SC84 microcomputer uses a 6MHz Z80 processor and has 64K bytes of ram but its main feature is that it can be used with a disc operating system and much readily available applications software I designed my first computer the Scientific Computer published by Wireless World in 1979 to gain experience with microproces sors This small system had novel features for its time including a hardware number cruncher and up to 5K byte of ram Looking back the Scientific Computer appears embarrassingly primitive but judging from correspond ence it served its purpose of giv ing readers the best possible introduction to microprocessors hands on experience This new design has a similar objective but it also permits the use of much readily available sof tware including word processors language interpreters and compil ers Retained features are the Z80 microprocessor the resident machine code operating system extended to provide extra com mands and general accessibility needed for engineering applic ations
170. IRELESS WORLD MAY 1984 WWW americanracdiohistorv com Full Colour Catalogue Send for your free copy now Philips PM3207 15MHz Oscilloscope 325 Compact portable lightweight oscilloscope designed for field and workshop use 15MHz bandwidth with 5mV sensitivity TV and auto triggering from either channel with adjustable level Add and invert facilities and X Y mode Large screen with internal graticule Philips PM3217 SOMHz Oscilloscope 850 High 2mV sensitivity dual trace 8 x 10cm display with small spot size high light output and illuminated graticule auto trigger mode TV triggering on line and frame Full X Y display facilities Comprehensive second time base facility Compact dimensions and low weight Philips PM 3215 Single time base 695 l ccc cu HN c Philips PM3219 Storage Oscilloscope 2675 Provides comprehensive cost effective storage of single shot transients and low frequency events Variable persistence and variable storage Auto erase between 1 and 10 seconds and read button facility Auto store up to 1 minute up to 24 hours in baby sit mode 2mV sensitivity at SOMHz Philips PM3256 75MHz Oscilloscope 1245 Tough light weight ruggedised unit with shoulder strap that canbe used in harsh service environments Fast trigger circuits Lo over 100MHz TTL triggering is standard Trigger view third channel and full X Y display Dual trace with 2mV sensitivity
171. IRELESS WORLD MAY 1984 radiohistorv com Experienced Graduate Engineers hildren of the 60 s On April 20th 1964 BBC viewers were given a choice of channels BBC2 was born Twenty years of achievement onward the BBC shows the same pioneering spirit Our approach to programming and broadcast engineering is as youthful enthusiastic and progressive as ever Earning us international respect as the world s foremost radio and television organisation The BBC s world is still growing We broadcast several thousand hours of programmes weekly to a national and international audience of millions H We require qualified Electronics Engineers with several years 45 practical experience to support the state of the art technical facilities which make our programmes possible Much of the ecuipment has been developed by in house experts and there is ample scope for the innovative engineer to make a genuine ccntribution to broadcast technology You will need to have a Degree HND HNC in Electrical Engineering oraHigherBTEC Diploma in Electronics Normal hearing and colour vision is essential Salaries are now on a scale from 8094 rising to 9791 in London Tr ese new pay scales apply from 1st April Allowances of about 1000 are paid in addition to these salaries to cover irregular hours of work Iff you are a Child of the 60 s an Engineer of the 80 s and a potential pioneer of broadc
172. LD MAY 1984 WWW americanradiohistorv com PHONE P M COMPONENTS LTD TELEX 0474 813225 SELECTRON HOUSE WROTHAM ROAD 966371 3LINES MEOPHAM GREEN MEOPHAM KENT DAISOOY PMCOMP p HL90 070 pcigs 0 80 RGA1000 10 00 VU29 450 3CX3 250 BBWS 150 Y4 185 395A 6 50 HL92 150 PCi86 085 RK29A 12 00 vU39 150 3CY5 1 50 68W6 5 35 888 250 108C1 1 50 A EE OO HLISS OD 350 PCL200 60 Rie Mo wn 00 3D6 450 caw7 150 307 138 10087 205 STOCK OF BRANDED HRZ 109 Pc goo 030 RPLIG 1200 w729 100 3021A 29 50 BW8 400 ior 025 iscce ae TT 7 HVR2 300 PCL805 0 90 RPY 3 250 W739 150 3D22 19 50 EM os 10GK6 1 95 185UG 25 00 A1714 1850 anor oso EF806S 14 50 JPS JA 60 00 P0500 350 RPYa3 250 X24 100 3waGT 250 soe 380 10P14 250 18587 150 A1998 1150 EABCS0 070 EF812 065 X394 soo P0510 365 RPYS2 250 X66L 435 485518 11509 2226 295 10P18 0 78 274A 15 00 A2087 1150 EAC9 250 EFL200 1 50 K3118 85 00 PEN4DD 2 00 RR3 250 37 00 X76M 195 4 654 59 00 ees 130 10LD11 1 00 307 5 00 A2134 1495 Eara2 120 EH90 9 72 kRe 3 asopo PEN25 2 00 RR3 1250 65 00 XC24 150 42504 65 00 SC3 195 10LD12 0 65 328A 1500 A2293 6 50 EAF801 3 50 EK90 0 72 KT8C 700 PEN4ODD 250 RS613 45 00 XC25 0 50 48Q7A 175 Ee 250 11E2 1650 388A 1750 A2521 2100 EB34 150 EL32 0 95 kr33c
173. LECTRONICS 8 Vo l Pet Swe OL Be ARE d b f SC 84 advanced Pa microcomputer So Farnell Instruments have been active in the manufacture and marketing of bench power supplies for almost 30 years The experience gained curing this time together with Farnell s philosophy of constant improvement and the introduction of new technology bench has culminated in the company s present position as the major U K supplier of bench power supplies power supplies Whatever your bench power supply needs Farrell would welcome the opportunity to discuss tham The company believes that almost any requirement can be met kom amongst its extensive range of unmetered and meered bench and sub bench analogue or digital single or mrulti output power supplies 5 Farnell FARNELL INSTRUMENTS LIMITED SANDBECK WAY WETHERBY WEST YORKSHIRE LS22 4DH TEL 0937 61961 TELEX 557294 FARIST G WW 601 FOR FURTHER DETAILS AN 800K If you re upgrading your BBC Micro to a disc system you can get unbeatable value from Opus For instance you can buy an Opus 5800 drive with 400K single density for only 259 95 And for only 120 extra we ll give you our new double density disc interface Specially developed by us it effectively DISC DRIVE SYSTEM A RECORD 380 doubles the capacity of your drive giving you an 800K system for only 379 95 And that includes VAT and carriage Our Doubl
174. MHz 4 Channel PUB in 000 00 1821A Timebase Plugin 1 000 00 1 200 00 3 000 00 1 800 00 VAT TO ALL PRICES Electronic TE er Philips PM3232 Dual Bean 10MH 495 00 PM3244 50MHz 4 channe 1 500 00 Tektronix 212 OOK Hz Dual Trace Miniscop 850 00 305 Battery 5MHz Dual Trace Oscilloscope DMM 1 000 00 335 Dual Trace 35MHz Small portable with delay T Base 1 300 0 434 ont 01 25MHz Storage 2 350 00 475A 250MHz Dual Trace Portable 3 300 00 ana POUM Dual Trace 2 500 00 731 3 MOM Hz Storage Ma nframe 2 225 00 7603 100MHz Mainframe 1 950 oo 7704A Scope DC 200MHz Mainframe 0 00 C12 Camera OA Telequipment D34 15MHz DT Battery Portable CT71 Curve Tracer SIGNAL SOURCES EH Labs 1398 Pulse Gen Hewlett Packard 214A Pulse Gen 950 00 11720A Pulse Modulator 8004A Pulse Gen 8011A 01 Pulse Gen 8013B Pulse Gen 8620C Sweeper Mainframe E2 100 oo 86240B Sweeper Plug In 2 Ns Hz 200 00 8640A Sig Gen 2 750 00 950 00 3 Carriage and Packing extra WWW americanradiohistorv com TEKTRONIX Logic Analyser 7D01 with DF1 16 Stored Channels up to 1024 words deep State and timing with up to 100MHz sample rate Price 2 00 Illustrated with 7603 Mainframe Extra RACAL DANA ele evi RTIII Counter Timer 9514 0 100MHz Counter 100nS to 10 Sec Period IEEE Interface Marconi TF2002B AM FM Si 88MHz with TF217 TF2008 Sig Gen TF2015 S
175. MHz AM FM 750 T TF2002 As above but AM only 450 MARCONI TF1066B AM FM Generator 10 470MHz 0 2uV 200mV output FM Deviation up to 100kHz MARCONI TF995A 5 AM FM Generator Narrow deviation model 995 covering 1 5 220MHz 450 TF2015 10 520MHz AM FM TF144H AM 10kH2 72MH 295 MARCONI TF1064B 5 AM FM Signal generator covering in three ranges 68 108 118 185 and 450 470MHz FM fixed deviations of 3 5 amp 10kHz AM fixed 30 225 DOLBY NOISE WEIGHTING FILTERS X Cat No 98A Noise weighting filters for CCIR ARM Signal to noise ratio measurements As new units 40 each 1 p amp p BECKMAN TURNS COUNTER DIALS Miniature type 22mm diam Counting up to 15 turn Helipots Brand new with mounting instruc tions Only 2 50 each RFI RECEIVER Stoddart Model NM52A RF Noise amp Field intensity measuring receiver 375MHz 1GHz c w power supply unit KAY SOUND SPECTROGRAPH Mode 6061B with Amplitude Display scale magni fier 85Hz 16kHz Complete sound spectrograph in excellent condition Wek STEPPER MOTORS ak Brand new stock of ASTROSYN Type 20PM A055 stepper motors 28V DC 24 steps per rev 15 oz in torque 100PPS Body length 24 diameter 2 shaft Ya diam x 414 spirally threaded Weight 160z Price each 15 p amp p 50p Connections supplied INC VAT SOO ROTO KOI ik MMMM YK MILLI VOLT MEASUREMENT ANALOGUE xe MARCONI TF2600 Twelve ranges 1mV 300V FSD Wi
176. NCY Hz 1200 baud FULL DUPLEX HALF DUPLEX CCITT V 23 channel assignments 390 450 Beil 202 channel assignments 1200 baud 387 1200 1700 2200 WWW americanradiohistorv com ort by Richard Lambley A Wireless World Design Fig 1 Full duplex modes allow simultaneous 300baud transmission in both directions In the half duplex modes the return channel is of limited bandwidth Bell 103 113 channel assignments 300 baud 600 baud 1300 1700 1500 MULTI STANDARD MODEM IXEENXUTTTNE t nS Main Transmitted data v Back Transmitter CAP C CAP Received carrier Mode control Interface control MC f Data terminal C ready 5 Xtal clock Xtaly lt Timing control a rs aes E U Fig 2 Block diagram of the AM7910 The mode control ins provide selection of a variety of common European and American standards No external filters are required key for l iude POM enn estan re 1 Viewfax 258 right is 2 Acorn icrone reste 14 ZX Spectrum Telesoftware interface available through Prestel 15 ahat re Telesoftware 16 The Gnome Service _Telesoftware 17 Telesoftware via a Gateway Browsers welcome Distel 18 Ine CET difference i gt 2 Telesoftware charts PR e cedi E eerd 5 Sell your programs on Prestel match the users modem 8 Frestel Education T software Index 9 Frestel Telesoftware Index 08 Mar 84 22 51 PORT 14
177. NT PRICE IS EX WORKS S AE FOR ALL ENQUIRIES PHONE FOR APPOINTMENT FOR DEMON STRATION OF ANY ITEM JOHN S RADIO WHITEHALL WORKS 4 WHITEHALL ROAO EAST BIRKENSHAW BRAOFORD BD11 2ER TEL 0274 684007 WANTED REOUNDANT TEST EQUIPMENT RECEIVING AND TRANSMITTING EQUIPMENT VALVES PLUGS AND SOCKETS SYNCHROS ETC 1848 LINSLEY HOOD DESIGNS 75Watt and 100W amps Audio Signal Generators 75Watt amp p c b 100Watt Mosfet p c b p amp p 50p S A E for leaflets TELERADIO ELECTRONICS 325 Fore Street London N9 OPE 1762 SURPLUS STOCK COMPONENTS We import and export all types of electronics mponents Monthly stocklists are available on request We also export vanous quality German products Enquiries are always welcome Agents wanted for our hobby kits Contact us at Resco Electronic Hessenbachstr 35 8900 Augsburg W Germany Tel 0821 524033 Tx 53776 RESCO D 2564 7 track portable recorder four head blocks 65 Car van lorry gas conversion kit 89 Flann microwave attenuator 35 50kV regulated variable EHT supply Brandenburg 89 Microgen laboratory projector 59 Binocular prismatic laboratory microscope 145 mechanical stage Fibreoptic laboratory light source 35 Braun Hobby professional electronic flash rechargeable batteries 39 Heavy duty multiple output power supplies Star Delta starter box 25 Al ternator control unit 35 Single to three phase converter Vacuum pump and mo
178. OINTMENTS VACANT 17 per single col centimetre min 3cm LINE advertisements run on 3 50 per line minimum 25 prepayable BOX NUMBERS 5 extra Replies should be addressed to the Box Number in the advertise ment c o Quadrant House The Quadrant Sutton Surre Cheques and Postal Orders payable to BUSINESS PRESS INTERNATIONAL LTD and crossed ALWAYS AHEAD WITH y SM2 SAS BRIGHTON POLYTECHNIC COMPUTER CENTRE TECHNICIAN DATA COMMUNICATIONS Salary upto 8 712 Tohelp maintain an extensive communications terminals and microprocessor service comprising 350 terminals and well over 50 microprocessors There is a small team dedicated to this task Additional development activities are undertaken improving the network by designing building and servicing various system components A progression scheme is provided for accellerated remuneration commensurate with the applicant s development skills Application forms and job description can be obtained fromthe Personnel Officer Brighton Polytechnic Moulsecoomb Brighton BN2 4AT Telephone Brighton 0273 693655 Ext 2537 Closing date 4 May 1984 2544 Appointments CUT THIS OUT Clip this advert and you can stop hunting for your next appointment We have a wide selection of the best appointments in Digital Analogue RF Microwave Micro processor Computer Data Comms and Medica Elec tronics and we re here to serve yo
179. PM 1 10 HP APPROX 15 Ib in 230V AC Cont Rating Non reversible Size 150mm 90mm x 85mm spindle 8mm dia 30mm long Complete with capacitor and relay for max load starting Offered at mere fraction of mfrs price 1150 inc p amp p amp VAT NM S CHECK METER 200 240V AC 50amp fully reconditioned 7 50 1 75 p amp p total nc VAT 10 64 SANGAMO WESTON TIME SWITCH Type 251 200 250 A C 20n 2 of every 24 hours 20 amps contacts with overede switch Diameter 4 x3 price 950 150 p amp p 1 12 65 inc VAT amp p amp p Also available with solar dia R amp T Other types available from stock NMS New Manufacturers Surplus R amp T Reconditioned and tested Good normally despatched within 7 days 6 05 1 p amp p I 8 11 inc VATI Personal callers only Open Saturdays 9 Little Newport Street London WC2H 7JJ Tel 01 437 0576 L TRANSTEL DOT MATRIX PRINTER Compact Serial Interface 230V With into 65 ea TELETYPE ASR33 DATA DYNAMIC 390 Printer Key board Punch amp Reader AS232 75 RACAL MODEM type2200 24 100 TRTSEMATRONS 1022 Modem 20 CREED 75 TELEPRINTER Very good condition 25 ea 9 MONITOR Cased Non standard with info 20 ea 12 MONITOR Cased Non standard withinfo 15 ea AZTEC 20 Black and white MONITOR Video In 50 va TV Style 20 MONITOR Black and white Video In 30ea 41 HP PULSE GEN 222A Repetition rate to 10M Hz 42 HP PULSE GEN 214A 200 watt pulse power Item No OSCILLOSCOPES
180. QVO640A u26 990 1e 00 Bane i99 aeee aos 206 50 sea 350 DH77 090 ECr oss E28 960 Mhios 4 00 1950 Uaz 300 ieza 495 ANG 109 Bse 38 20L1 oss sea2 1100 DH79 0 56 ECFB6 170 E290 135 Mig 450 2QV07 50 U4 6 95 1824 14 9 6AJ4 2 00 z 415 20P 0 55 5879 3 90 DH149 2 00 ECF200 185 F6064 2 95 MS4B 550 63 50 U50 2 00 1835A 29 50 6AJ7 200 OG 070 20P3 0 60 5894 39 50 DK91 0 90 ECr202 185 FW4 800 2 95 MUl4 150 0203 20 U82 300 10 120 6AKS T pee 395 20P4 1 05 5899 4 50 DK92 120 ECF801 0 85 G1 371K 30 00 N37 1250 42 50 U191 070 1C5SGT 100 6AK6 2 00 Fehon 59 20P5 3135 5963 2 00 DK96 2 50 ECF804 6 00 G55 1K 9 00 N78 385 QQZ06 40A U192 100 1D5 100 GALS 0 60 ete 250 21LU8 250 5965 2 25 DL35 1 00 ECFB05 2 50 G180 2M 9 00 OA2 0 85 45 25 U193 0 65 FD 0 90 6AM4 325 6L19 95 2481 39 50 5993 8 00 DL63 1 00 ECFgo6 10 25 G240 2D 9 00 Oa2wA 159 QS72 20 150 U251 100 1G3GT 100 6AMS 6 00 6L6GC 2 95 29L6GT 175 6005 1 95 DL70 250 ECH3 250 G400 1K 1400 Qai 250 QS75 40 300 801 0 75 its 0 60 GAM6 1 50 6GCIGE 3 95 25806 1 75 6012 16 00 DL3 250 ECH4 3 00 GC 0B 1750 op oas QS92 10 5 00 UABC80 065 1L6 150 6ANS 395 6L i 29C 1950 6021 395 DL91 150 ECH35 245 GC OD 1750 OgjwA 125 QS95 10 4 85 UAF42 100 JLA6 1 00 GANBA 2 95 6L6GT 115 3oC17 Qo 6057 2 50 OL92 150 tCua2 100
181. R 1K 4K7 10K 47K 100K 680R 6k8 68k 680k 1M 25 pcs 330R 470R 1K5 2K2 3K3 TRADE ENQUIRIES WELCOME i os M NER AIRLINK TRANSFORMERS LTD SOR 9d 91k IM Extra special 1 of each kit 22 l 28 Bullfields Sawbridgeworth Herts Tel 0279 724425 ORION SCIENTIFIC LTD 16 Orange Street London WC2H 7ED CIRCLE 018 FOR FURTHER DETAILS CIRCLE 084 FOR FURTHER DETAILS 80 WIRELESS WORLD MAY 1984 AL 5 mA onem WA amaereanradiohietOFV DOT eaae ee STURDY CASSETTE RECORDER Basing their efforts on a cassette recorder designed for use in schools Bell amp Howell and Leasalink Viewdata have combined their talents to produce a cassette recorder 3179CX for use with microcomputers Pointing out that the use of cassettes for computing accounts for much heavier use than with audio the player has been manufactured with a heavy duty case mechanism and circuit boards said to be hard wearing and shock resistant All the usual facilities are provided including cue and review and a tape counter while the recording level can be automatic or manually controlled Frequencies up to 8kHz can be recorded which the makers claim is ideal for computer use The recorder also doubles as an audio machine Bell amp Howell Alperton House Bridgewater Road Wembley Middlesex HAO 1EG WW 216 WIDEBAND OP AMPS Thought to be ideal for use in high speed data and signal applications the Teledyne Philbrick TP
182. SUP TLO74 100p 68821 250p 745289 225p DS8836 150p ENCODER 14 756 250p 7460 60p 74L546 gop 74L3643 250p 4072 30P CM7217 S00p MC3340P 200b TLOB 45p 6829 1250 33415 600p 025938 225p 15 0 200p UD Gor J LS48 90p 74 8643 1300p 4073 30p clans oop MG3340P 200p TOR e 6840 375p 93425 Goch DS8880 170P WV eer 160 200p Hi Eb onin de nce we ofe M nodi MENO Qe lun rose Ee Hin E Qu em Wort Wl me 3 C IPS aja amp b 7als59 Sop 74L8845 400p 4077 30b tezis 300 MFIOCN 360b TOBE S0P G Bso 250p 220 TBA Miciaaa oop 4CSZSN 500P s969 150p 9075 505 74LS73A 36p 4 S668 80p 4078 3Op E137 3505 oUs40 900P E170 Bon 6852 250p MC3418 950p more 20 0 450p Jas ad 74LS74A 100p 74LS669 80p 408 30p 2 7 150b MK50398 790p T170 XP 6854 700p ROMs MC3446 250p 240 300p 7380 60b 74LS75 S0p 7419670 130p 4082 30p E351 60 MLS20 500p UR 1003 3 9357 68B54 850p PROM MC3459 450p Peay AOE 48 0 175p 7481 180p 74LS76A 36p 4L9682 350p 4085 S0P irasa 100p _ V M6221A UA2240 120p 6875 570p EE Mc3470 esop oiii 700p 216 300p 7483A 90p 74LS83A 0p 74 3684 400p 4086 70b LF355 1o0p nesat 1905 UAAI70 200p 8153 350p 745188 180p MC3480 850p C Gma116 Boop PXO 1000 1200p 7484A T80p 74LS85 Op 74LS687 450p 4089 125P Cf3 6F 100p Nesa 1905 ULN2003A 8 1100P 748287 200p McsagS 3005 4 02B 7560 7485 120p 74 586 40p BETS 409 49P E357 130p NESea 1
183. Switchable CCITT or BELL 103 amp LIFETIME Thousands of components al giveaway prices Guaranteed to be worth LAX34 AL LA34 tractor feed 85 00 202 Housed in ABS case size only 2 5 x 8 5 at leas 3 umes what you pay Unbeatable value Sold by weight x 9 286 00 VAT 2 5kls 4 25 pp 1 25 5kis 5 90 1 80 x ee data or details on other EX Ip tOkis 10 25 pp 2 26 20kis 17 50 4 75 Call for details All types of Computer equipment and spares wanted for prompt Carnage on all modems 10 00 VAT y Bt A PRICES PLUS VAT CASH PAYMENT FAM INE B 4 prices quoted are for UK Mainland paidcash wit erin Pounds Stirling PLUS VAT Minimum ordervalue 2 00 Minimum Credit Cm wee Cardorder 10 00 Minimum BONA FIDE account orders from Government depts Schools Universities andestablished companies r1 i 20 00 Where post and packing not indicated please ADD 1 00 VAT Warehouse open Mor Fri 930 5 30 Sat 10 15 5 30 We reserve the right to change prices and specifications without notice Trade Bulk and Export enquiries welcome mic AM Biggin Way Upper Norwood London SE19 3XF FX ae 1000 s of EX STOCK spares for DEC PDP8 PDP11 PDP15 amp periperhals NUNC I Telephone 01 679 4414 Telex 27924 CIRCLE 076 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 83 WWW americanradiohistorv com ly 84 Sais Fe MARCONI SIGNAL de CONE 0 SENERATURS TF2002A S illustrated 10kHz ife eme c amp 8 72
184. T TIES OF COMPONENTS BECOME REDUNDANT WE ARE CASH PURCHASERS OF SUCH MATERIALS AND WOULD APPRECIATE A TELEPHONE CALL OR A LIST IF AVAILABLE WE PAY TOP PRICES AND COLLECT R Henson Ltd 21 Lodge Lane N Finchley London N 12 5 mins from Tally Ho corner Telephone 445 2713 0749 CIRCLE 012 FOR FURTHER DETAILS Ex Gov 27fttelescopic aerial close to 5ft Good condition complete with ali base amp fittings 45 P amp P paid Callers welcame 25 Pye Pockettone Nightcall for PF1 TX RX New boxed 17 00 Whip aerial Ex Gov 4tt collapsible 1 00 Crystals HC6U Ex Equip 5 000 mc s 7 000 mc s 8 0001 M C me s 9 000 mc s Also Glas Crystat 100 Kc s to fit B7G base All at 2 p amp p paid Telephones Type 708 good condition 5 p amp p paid Small 230V fans 4in X 2 1 2in 2 500 r p m 4 50 p amp p paid Pye Pocketfone PF battery charger 12 way with meter 10 p amp p paid PF TX battertes 2 each p amp p paid We have also for sale the following items which are too numerous to advertise Callers only valves transformers tuning units receivers bases wave guide scopes plugs sockets power units capacitors aerials headsets cable signal generator BC221 Ni Cad batteries tor Pye PF 1 RX Sfor 2 p amp p paid Min order5 All these batteries are ex eq but good condition Bargain Parcels 14lbs at 10 28lbs at 20 and 56lbs at 40 p amp p paid Contains pots res diodes tagboards caps chassis valve holders etc G
185. TT 25011 5 50 50p p amp p 5 90 inc VAT 100 WATT 1 5 10 25 50 100 250 500 1k Y 1 5k 9 2 5k Y 3 5k 0 7 75 75p p amp p 9 77 inc VAT Black Silver Skirted Knob catbratea in Nos 1 9 13n dia brass bush Ideal for above Rheostats 30p ea VAT WHY PAY MORE L MULTI RANGE METER Type MF15A ac dc volts 10 50 250 500 1000 Ma0 5 0 10 0 100 Sensitivity 2000V 24 range diameter 133 by 93 by 46mm inciuding test leads Price 10 35 inc VAT amp p amp p New ceramic construction heavy duty brush assembly continuously rated 25 WATT 5 10 25 50 100 150 250 300 500 1K 1 INSULATED TESTERS NEW Test to EE Spec Rugged metal construc uon suitable for bench or field work con stant speed clutch Size L 8in W din H amp in weight 6lb 500V 300 megohms 49 p amp p 2 58 85 nc VAT 1000V 1000Mt 55 em p amp p t2 65 55 incl VATI SAE for leaflet GEARED MOTORS 5 rpm 240V AC Mt by Carter NMS 38 3 rpm GEARED MOTOR Torque 35 b in reversible 115V AC inc start capacity Price 11 55 p amp p itotalinc VAT 15 58 NMS Suitable TRANSFORMER 230V AC operation Price 4 50 gt 50p p amp p total incl VAT 5 75 CROWN 37 rpm 200lbin approx 110V AC reversible geared motor Price 35 p amp p 14 50 46 42 inc VATINM S Suitable transformer for above 10 p amp p 1 501 13 22 inc VAT CROWN 42 rpm 110 230V A C 50 Hz 100 Ibin approx Reversible geared Motor Price 18 15 2 50 p amp p total incl VAT 23 75 120 R
186. V8 7V5 8V2 9V1 10V 11 f 7 Watt ssx ozo ii BiB aso VEI GOV 23V 22 VIO OPEN MONDAY TO FRIDAY 9a m 5 30p m 1R 10K 0 20 14 Pin DIL 0 15 24 HOUR ANSWERPHONE SERVICE yx j 14 Pin DIL Q THERMIS s BATTERIES ACCESS AND BARCLAYCARD ORDERS WELCOME 11 Watt ox oz 030 l MANY OTHER ITEMS AVAILABLE 9 16 Pin DIL 0 17 VA1040 023 7V Power Mike 1R 10K 0 26 OCTAL 035 VA1056S 023 Bateries CANS 027 9 1d UK DRDERS P amp P 50p PLEASE ADD V A T AT 15 17Wall x o GAB ois Vaseeg OD ELA me 85 975 vaca gee elon EXPORT ORDERS WELCOME CARRIAGE POST AT COST CIRCLE 053 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 91 WWW americanradiohistorv com a Vigilant Micon HF Communications Receivers MICROPROCESSOR CONTROLLED RECEIVERS Type SR 530 USB CW AM Telex 10 Hz Steps Marine Type SR 532 USB LSB AM CW 10 Hz Steps Static Transportable Type SR 531 USB LSB AM CW 100 Hz Steps Static Transportable md migun COMMUNICATIONS RECEIVER v SR532 AF GAN SUPPLY WIOL RAS DESIGNED AND MANUFACTURED TO HIGHEST INTERNATIONAL SPECS Freq Range 50 KHz to 30 MHz Memory 200 Channels Freq Mode Filter increments 10 Hz or 100 Hz Steps Scanning Full memory or discreet parts Stability 1 Partin 10 7C Automatic or Manual Stop Tuning Keypad and Spin Wheel Manual step on or Reverse Power Supplies 110 240V AC and 24V DC Dwell Variable from Keypad 1 to 9 seconds FULLY MODUL
187. WITH SB ADAPTOR ARU 0A 100 WITH MANUAL REDIFON TTIO OR TT11 AUDIO TELEPRINTER CONVERTOR SOLID STATE TESTED WITH CIRCUIT 25 CREED TYPE 75 TELEPRINTER 0 AND 75 BAUOS FOR USE WITH ABOVE CONVERTOR 25 OSCILLOSCOPES CT436 DUAL BEAM OSCILLOSCOPES 6Mcs 45 TEKTRONIX 647A 00Mc s QUAL TRACE SOLID STATE 350 WITH MANUAL MARCONI TF995 SIGNAL GENERA TORS FROM 2Mc s OR 5Mc s TO 220Mc s AM FM A2M 80 A3 80 A5 150 WITH MANUALS TF2606 DIF FERENTIAL DC VOLT METER OTO 1100 volts 100 TF2002 AM SIGNAL GENERATOR YKc s TO 72Mc s 300 TF20QQAS FM AND AM SIGNAL GENERATOR 0Kc s TO 22Mc s 600 TF21708 DIGITAL SYNCHRONIZER FOR ABOVE 350 TFYOSGB 6 FM AM SIGNAL GENERATOR OMe s TO 470Mc s 300 TF1245 CIRCUIT MAGNIFICATION METER AND TF1246 OSCILLATOR 200 HP SIGNAL GENER ATORS 6208 7T0 G GS 150 608 0 420Mc s 70 612A 450 1200Mc s 200 MARCONI AF WATT METER CT44 NOT ABSORPTION 700 MICROWATTS TO 6 WATTS IN 10 RANGES SWITCHED 2150 Ohms 45 TFES3A AF WATT METER MILLIWATT TO 10 WATTS 25 Ohms TO 20K Ohms IN 48 STEPS 65 THYRISTOR TEST SET Cross VOLTAGES UP TO 2kV 100 TEKTRONIX 4002A GRAPHIC COMPUTER TERMINAL WITH JOYSTICK 400 TEKTRDNIX 4601 HARD COPY UNIT FOR USE WITH ABOVE 150 BOTH UNITS FOR 500 RACAL DIGITAL COUNTERS TYPE BOIM 125Mc s 50 RACAL 636 COUN TER 35Mcs 90 VAT AND CARRIAGE ON ABOVE ITEMS EXTRA ALL ITEMS ARE BOUGHT DIRECT FROM HM GOVERNMENT BEING SURPLUS EQUIPME
188. X LIMITED Sowter Transformers With 40 years experience in the design and manufacture of several hundred thousand transformers we can supply AUDIO FREQUENCY TRANSFORMERS OF EVERY TYPE YOU NAME IT WE MAKE IT OUR RANGE INCLUDES Microphone transformers all types Microphone Splitter Combiner transfor mers Input and Output transformers Direct Injection transformers for Guitars Multi Secondary output transformers Bridging transformers Line transformers Line transformers to G P O Isolating Test Specification Tapped impedance matching transformers Gramophone Pickup transformers Audio Mixing Desk transformers all types Miniature transformers Microminiature transformers for PCB mounting Experimental transformers Ultra low frequency transformers Ultra linear and other transformers for Transistor and Vaive Amplifiers up to 500 watts Inductive Loop Transformers Smoothing Chokes Filter Inductors Ampli fier to 100 volt line transformers from a few watts up to 1 000 watts 100 volt line transformers to speakers Speaker matching transformers all powers Column Loudspeaker transformers up to 300 watts or more We can design for RECORDING QUALITY STUDIO QUALITY HI FI QUALITY OR P A QUALITY OUR PRICES ARE HIGHLY COMPETITIVE AND WE SUPPLY LARGE OR SMALL QUANTITIES AND EVEN SINGLE TRANSFORMERS Many standard types are in stock and normal dispatch times are short and sensible OUR CLIENTS COVER A LARGE NUMBER OF BROA
189. Y3 3 00 1 25 EL 1 5 M8096 6 80 PCF808 1 70 STV280 80 2759 25 00 6AG7 3 00 6KD6 7 00 30P19 2 50 6058 12 34 CIK 20 00 8 00 EL91 9 69 M8097 8 10 PCL82 2 00 21 00 ZMIOO0 8 00 6AH6 5 00 6L6G 3 00 30PL1 3 00 6089 6 00 C3JA 22 00 1 5 EL95 2 00 M8098 6 15 PCL83 3 00 sus 5 00 ZM1001 8 00 6AKS 5 99 6LeGA 3 00 30PLI4 L80 6061 6 00 CA 22 00 380 00 ELI56 30 00 M8099 8 00 PCL84 2 00 St42 10 0 ZM1020 9 00 6AK6 2 50 6L6GC 3 00 3OPLIS 1 80 6063 3 75 D 4l 25 00 4 50 EL360 8 50 M8100 9 52 PCL85 2 50 TD03 10 35 00 ZMi021 9 00 6AL5 150 6L6GT 3 00 35W4 1 00 6064 8 58 DA42 18 70 4 50 EL500 504 3 00 M8136 10 23 PCL86 2 50 TD03 10F 35 00 ZM1022 9 00 6AM4 4 00 6L7 2 50 50C5 1 50 6067 10 23 DAF9 1 5 4 50 EL509 7 00 M8137 10 2 PCL805 85 2 50 TTI5 50 00 ZMIO23 9 00 6AMS 9 68 6N2P 2 50 75Bl 6 05 6072 6 00 DAF96 1 75 175 EL821 13 00 M8140 6 00 PD500 6 00 TT21 23 00 ZM1040 19 36 6AM6 6 02 6N3P 2 50 75C1 4 50 6080 14 00 DET22 35 00 1 75 EL822 13 97 M8141 6 50 PEU6 40N 45 00 TT22 23 00 ZM1041 16 66 6AN5 4 75 6N7 3 00 85A1 7 50 6097A 235 00 DET24 49 00 1 75 EM34 5 00 M8142 8 75 PFL200 2 50 TT100 60 00 ZM1042 17 7 6ANSA 3 50 6P25 4 00 85A2 4 45 6097B 200 00 DF91 1 75 1 5 EM80 150 Msl44 7 50 PL36 2 50 TY2125 65 00 1B3GT 3 00 6AQS 225 6Q7 375 90AG 12 96 6146A 8 25 DF96 1 75 175 EM8 150 M8149 6 50 PL8I 1 75 TY4 400 75 00 1B24 25 00 6AS6 8 66 6R7 325 90AV 12 96 6146B 8 25 DK91 1
190. a Power supplies of 5v 12v and 12v ere required Front panel is 137mm square and the unit is 200mm deep including rear connector Offered in good ex equipment condition at a fraction of original cost ONLY 44 50 inc VAT and postage Data inc circuits and layouts of PCBs 3 50 DOLBY B NOISE REDUCTION IC LM1011 30 Watt Complete Kit 72 35 Watt Complete Kit MosFet O P 79 50 Marvellous opportunity for home experimenters build your The foll l 45 Watt Complete Kit MosFet O P 83 50 own noise reduction system Supplied complete with cicruit Mass Ea E CEU E all are suitable Reprints of 30 Watt Article from Hi Fi News 50p growing typicai ape Absolute knockout price only iC 20 Permalloy Stereo Haad This is theietandardinesd ited Ri 0 tor two inc and post if e s 1 standard he itted as eprints of MosFet Postscript to above 30p original equipment on most decks 5 11 HM90 High Beta Permalloy Head A hard wearing higher per COMPLETE STEREO CASSETTE DECK formance head with metal capability 8 06 Brand new high quality top loading Cassette Deck complete with Record Play electronics Supplied with connection data and circuit diagram Automatic chrome ferric switching Only needs 9v DC supply Total price only 18 34 inc VAT and post HS16 Sendust Alloy Super Head the best head we can find Longer life than Permailoy higher output than Ferrite fantastic frequency response 9 91 HQ551 4 Track
191. a week service ForFREE Unit 1 Shire Hill Industriai Estate Telephone 0799 21682 and give us your Barclaycard Access American catalogue Saffron Walden Essex CB11 3AQ Express number and your order will be in the post immediately tick box Telephone Saffron Walden 0799 21682 L SS EE a ee 4 CIRCLE 048 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com ae e i COMMENT Plus a change Once in a while the appearance of Wireless World changes a little as fashions in typography and layout evolve In recent times the changes have been somewhat tentative a bold face heading here a rule here and a bit of unjustified typesetting meaning ragged not unnecessary somewhere else It is even possible that they have been so slight that not many readers have noticed and also possible that uncoordinated small changes here and there led to a style which did not hold together as well as it might have With that in mind our designers and editorial people decided that the moment was right for a full blooded effort starting from scratch to make the journal more attractive to the eye since recent printing and production charges have made possible the introduction of colour and rather better paper The new layout of pages is a great deal more in line with the best of current practice than was the earlier style and is we think fresher and visual
192. aid The unit is powered by a PP3 battery from which it draws about 10mA during normal use A reachargeable battery can be fit ted if required there is a charger socket on the front panel The preset control are accessible with the help of a trimmer tool but the patient need be concerned only with the on off switch and the signal received light Prototypes have been in use at the Frenchay Hospital for several months with good results Dr Enderby reports significant improvements in the intelligibility of patients using the aid and she describes her initial tests as ex tremely encouraging One deve lopment she has suggested is the possibility of replacing the buzzer with a body worn vibrator This would help patients with hearing problems and might enable the aid to be used by others in every day conversation without the embarrassment a buzzer causes Phil Pickersgill is a design engineer with Racal s mobile communications company in Reading He studied electrical and electronic engineering at Bristol University graduating in 1982 Since then he has worked on the design of a var iety of h f mobile radios Nic Stewart is an assistant consultant with General Tech nology Systems a small inde pu consultancy based in ntford Middlesex He stud ied at Bristol University grad uating with a degree in geogra phy in 1981 WIRELESS WORLD MAY 1984 ZX81 INTERFACE 2X81 generation and measurement int
193. all types of microcomputer in use rather limited results but this by the end of 1983 wouldbe4 mil simply reflects the difficulty of the lion units costing 3550M But problem The interval between another now thinks withthecon the first substantial research 63 WWW americanradiohistorv com Lu eet uen uem One longs indeed for a unit of knowledge which might be called perhaps a wit analo gous to the bit K E Boulding 64 THE INFORMATION SOCIETY work in the 70s and the applica tion of continuous speech recog nition may well be 50 years recent television pro gramme described progress with synthetic speech a much easier achievement and then showed the recognition of single words and short phrases by a machine which had almost cer tainly been preceded by a human machine training session which was not mentioned This led nat urally to speculation and an inter view firstly with an equipment supplier about this here and now technology and then with a lay audience about how comfortable they would feel when conversing with machines This kind of logi cal extension from one thing to another against a background of impressive rows of knobs and c r t screens encourages false expectations Very large screen display devices may become generally available during the next 5 years 60 years after thec r t not much changed today was first intro duced by v
194. ally invisible on the final display pic ture The response trace shown in Fig 43 was taken with the notch a _ 2 Mullard MR25s are used to improve 160V ton y 560 Chroma Red drive control I Y 2k 2k7 iN Character inputs 27p BC 158 Earth if not gt used a amp vdc E end T match between stages HT T 4n 1k a BF422 33 Green O M pk pk sync fip t 2 2Vde 1045Y pk pk sync tip Bie 150p E Ge K crt cathodes e HT To other stages 1k Black level Pins 12 14 amp 16 Up fo 5V pk pk ts available as video drive typical blanking level of 2V amp max white level of 9V WIRELESS WORLD MAY 1984 switched into circuit by connect ing the gate of the f e t to the 12V rail so that the colour sub carrier centre of the trace is removed Alternative circuits between the i f and decoder The added circuit board shown last month may not be appropri ate if the tuner i f uses a surface acoustic wave filter with the colour subcarrier frequency 4 6dB down or if the tube cannot display video signals in the region 3 5 to 5 5MHz or if the received signal is poor To investigate these difficult ies reception tests were carried out on a South of England trans mitter with the results shown in Figs 44 to 51 The test equip ment was first placed back to back to determine response flat 12V rail Viewer picture controls
195. americanradiohistorv com LANGREX SUPPLIES LTD Climax House Fallsbrook Rd Streatham London SVWV16 6ED RST I SEMICONDUCTORS BE257 0 27 GEXS4 5 00 QAZ207 1 50 OC205 2 75 ZTX504 0 21 2N1671 5 00 2N3819 0 30 d te BD132 0 48 BF258 0 27 GBM 1 50 Ocl6 2 50 OC206 2 75 ZTXS3 0 244 2N1893 0 32 2N3820 0 39 AASI9 0 10 ASZIS L20 BCH3 oal BD135 0 40 BF259 0 28 GMO378A 1 75 OC20 2 50 OC207 150 ZTX550 0 25 2N2147 4 00 2N3823 0 60 AAY30 0 17 ASZ16 110 BCI77 0 28 BD136 0 40 BF336 0 34 KSI00A 0 45 OC22 2 50 OCP71 200 IN9I4 0 05 2N2148 375 2N3860 1 00 AAY30 0 17 ASZI7 100 BCI78 0 28 gpi3 0 40 BF337 0 33 MJE340 0 60 OC23 4 00 ORPI2 100 IN9I6 0 09 2N2218 0 32 2N3904 017 AAZ13 0 15 ASZ20 2 30 BCUS 0 8 BDI38 048 BF338 036 MJE370 073 OC24 3 00 R2008B 2 00 IN4001 0 06 NEMO 03 A AAZIS 0145 ASZ21 2 50 BC182 0 11 BD139 0 48 BFS21 4 00 MJE371 0 71 OC25 1 00 R2009 2 5 IN4002 0 06 2N2220 00 2N3906 017 9 15 AUMS 250 BCI83 9 1 BDI40 0 50 BFS28 2 25 MJES20 0 47 OC26 1 50 R2010B 2 00 1N4003 0 06 2N2221 0 20 2N4058 0 20 0 55 AUYIO 3 00 BCI84 0 11 gpli4 2 00 BFS l 0 20 MJES21 0 73 OC28 2 00 TIC44 027 1N4004 0 07 2N2222 0 20 2N4059 022
196. amp P or Carriage and V A T at 1596 on total must be added to all orders Callers very welcome strictly be tween 9 a m and 1 p m and 2 and 5 p m Monday to Friday inc Barclaycard and Access taken Official orders welcome 5 STATION ROAD LITTLEPORT CAMBS CB6 1QE PHONE ELY 0353 860185 CIRC BREAKING TEK 545A SCOPES FOR SPARES CRT type T543 P2 12 each Mains Transformers T601 15 High Volume Transformer T801 with valves 25 Also Switches Knobs Fans Capacitors and Metalwork RADIOSONDE RS21 METEOROLOGICAL BALLOON TRANSMITTER with Water Activated Battery contains all weather sensors fully solid state 5 each plus 1 p p ptus V A T BARCLAYCARD Access 072 FOR FURTHER DETAILS SATELLITE RECEIVING EQUIPMENT MUSA amp American pattern are listed in our Catalogue 1 9M 2 5M and 5M Harrison Dishes Sat Tec R5000 4GHz Receivers Avcom COM 2B 4GHz Receivers California Amplifier 4GHz LNAs Chaparral Horns Harrison Feed Horns Demonstrations by appointment only Dealer enquiries welcome Write or call foryour free copy For further details contact Harrison Electronics 22 Milton Road Westcliff on Sea Essex SSO 7JX Telephone Southend 0702 332338 114 Wardour Street London W1V 3LP England Telephone 01 434 3344 amp 01 437 1892 Telex 21624 ALOFFD G CIRCLE 004 FOR FURTHER DETAILS 24 WIRELESS WORLD MAY 1984 WWW am
197. an personnel This tradition changed following the war time successes of Bletchley Park with the formation of the Composite Signals Organization as an inherent part of GCHQ A typical example of the resulting changes can be safely quoted without breaching security since the station closed down several years ago Flowerdean near Winchester was for many years a Y service h f station of the Royal Navy It became under the GCHQ regime a civilian manned CSO station run from Cheltenham Although Service signals personnel still man some intercept stations the direct role of the Services in this work as in many other branches of Defence communications has clearly decreased The Royal Navy always quick to take umbrage at any attack real or apparent on its assumed role as the senior Service has consistently opposed such diminution of its responsibilities Stereo on tv further series of test transmissions of the BBC s digital stereo tv system suitable for use on terrestrial networks were carried out early in March in the London area on the Crystal Palace high power transmitter and its local relays This followed earlier tests in the hilly South Wales area from Wenvoe where the main purpose was to check digital performance under multipath propagation conditions The London tests concentrated on compatibility with the wide range of television receivers in use The system uses a phase modulated second sound carrie
198. and selected at will The 8253 needs an accurate clock signal best derived using a crystal Readily available but running at 6 5MHz the ZX81 s own clock is not convenient for this purpose so I added a 1MHz crystal oscillator The LM3l comparator is readily available and operates from a single supply rail but any similar i c may be used Improved resolution at higher frequencies could be obtained by using a 2MHz crys tal Using the 8253 counter timer i c Each of the 8253 timers is set up independently by sending a con trol word to the device The con trol word selects the operatin mode and has to be followe immediately by associated data In mode zero the data presets the count to be decremented while in mode three the data sets the divi sion ratio Control word format is according to Table 1 Bits four and five select the form in which the data is loaded which can be least significant byte only most significant byte only or least significant byte followed immedi ately by the most significant byte A further option is to read and latch the counter The double byte load option is used here Binary count 1s selected by a zero at bit zero Yet another facility is provided for reading the count after decre menting Sending control word 80 reads the count and transfers it to a separate register The register is then simply read using two peek operations Addresses for the counters are 49156 for counter zer
199. anding performance with versatile triggering to BOMHz Sensitivity 1mV to SOMHz and 2mV above Bright display from 14kV CRT Switchable 1kHz 1MHz probe calibrator Dual trace delayed sweep X Y operation Z modulation internal illuminated graticule and component tester Hameg HM705 70MHz Oscilloscope 588 General purpose scope with multitude of operatiing modes and trigger facilities Extremely bright and well defined displays with 8 x 10 cm screen and internal illuminated graticule TV triggering Z modulation X Y dispaly facilities and sweep delay mode Dual trace ADD 15 VAT TO ALL PRICES Carriage and Pack ing extra Electronic Brokers Ltd 61 65 Kings Cross Road WIRELESS WORLD MAY 1984 WWW americanradiohistorv com London WC1K 9LN Tel 01 833 1166 Telex 298694 13 HORIZONTAL OR VERTICAL RANGE FROM 3 10 SOCKETS ALL EX STOCK SPECIALS TO ORDER OLSON ELECTRONICS LIMITED WHEN IT COMES TO POWER FOR RACKS IT MUST BE OLSON 9 7 LONG STREET LONDON E2 8HJ TEL 01 739 2343 TELEX 296797 CIRCLE 028 FOR FURTHER DETAILS COMPLETELY NEW EQUIPMENT Westminster Mobile Sets type W15AM tuned and including crystals for 121 7 Mc s complete with loudspeakers microphone and mobile aerials Price 95 00 each Pye SSB type 130M 2 Channell Price 440 00 each Pye SSB type 130M 4 Channell Price 515 00 each For above PSU 12 VDC Price 88 00 each PSU 230 VAC Price 105
200. anies The facilities and resources rank alongside the most technically advanced inthe world today The total environment is completely conducive tothe wide range of research projects which continue to achieve the successes for which we carry worid recognition There are vacancies intwo teams for people qualified at least to HNC or HTEC level and having relevant experience in DIGITAL FLAT CATHODE RAY TELECOMMUNICATIONS TUBES This team is involved in an advanced An opportunity to join a team working on Integrated Services Digital Network embracing Advanced Vacuum Tubes building and testing subscriber access through digital transmission sub assemblies through to complete units The task will involve exploitation of both Digital using a wide variety of mechanical and physical and Analogue Signal Processing techniques and processes As a key member of this team you will be directly concerned with construction testing and evaluation of hardware systems if you believe that your experier ce and qualifications would equip you for either of these positions we would be pleased to hear from you Conditions of service andrewards reflect those of the parent group renowned for their forward thinking and enlightened policies Assistance with relocation is available if required D L PS Please apply to Chris Nye AF Appointments Co ordinator Personne Department R E SEARCH Philips Research Laboratories Cross Oak Lane
201. are Europe s largest specialists in quality second user test equipment computers and associated peripherals All second user test equipment offered by Electronic Brokers is calibrated to mect the original manufacturer s sales specifications and guaranteed for 12 months Our latest catalogue contains full details of our extensive inventory Contact us for your free copy now BRYANS SOUTHERN XY T Recorder 25000 THESE UNITS ARE UNUSED A4 Size X Y Ranges 1mV to 1V Per CM Slew Speed 49 CM Second Timebase Price 750 TEKTRONIX 0 1 to 10 SEC CM Portable Data Analyser 308 For Timing State Serial an nature Analysis ata Lines sone Price 2 100 ANALYSERS Hewlett Packard 334A Distortion Analyser 1611A Logic Analyser 358 1A Wave Analyser Tektronix AA501 opt 01 Distortion 10Hz 100KHz to Less than 0 0025 1 450 00 DF1 Display Formatter For 7001 500 00 492 o E 01 08 Spectrum Analyser AX 25 tras and isda e N opt racker an nput plu in BOHz E78 do bo 7 12 Spectrum ae 100Kt GHz 6 000 00 7118 spectrum Analyser 1 5G GHz 3 950 00 TR502 Tracking Generator 100KHz m x BGHz for use with 7L13or 7L14 3 000 00 TR503 Tracking Generator for 492 496 series 4 250 00 7D01 16 Channel 100MHz Sample Rate 500 00 7002 01 Logic Analyser EF 950 00 OSCILLOSCOPES Hewlett Packard 1332A High Quality CRT Oise os 9 6 x 11 9cm 50 00 1 pone 1 OOMHz Variable Persistance ae 100 00 1809A OO
202. are the Hi Res package which uses BBC mode 0 to give a 265 by 256 image which may be stored on tape or disc anda Photo Graphics package which uses mode 2 and offers false colour representation of different shades of grey The system including tv camera software and documentation cost 495 For an additional 99 it is possible to add an RGB filter system with the appropriate software to give a true colour image in mode 2 Digithurst Ltd Leaden Hill Orwell Royston Herts SG8 5QH WW 212 NEW PRODUCTS SINGLE LENS VIDEO PROJECTOR new projector has been specifically designed to work with computer data output The ECP 1000 differs from most other video projectors by combining the RGB images internally working like a tv camera in reverse and projecting the combined image through a single lens This avoids the registration problems often encountered with three lens projection tv and the system is capable of displaying high resolution images with 600 lines of 1024 elements The input signal is fed to the three c r ts which are positioned around a cube of dichroic mirrors the mirrors within the cube have been aligned by laser light and the dichroic coatings up to 35 layers on each mirror have been selected to match the wavelengths of the outputs from the c r ts This ensures that the brightest image is available for projection The c r ts are also liquid cooled to improve their ef
203. arried out to a high standard by competent profes sional engineers Trontect electronics Design Services 81 Finchampstead Rd Wokingham Berkshire Tel 0734 790103 2439 PROFESSIONAL MAST ERECTION SERVICE for monile radio Building mounted masts from only 5 per foot up to 60ft 75ft or more 7 50 per foot Ground standing masts may be extra for concrete base etc CTVR Comms 1 Bottesford Lang Allington Grantham Lines Tel 0400 81296 2539 TURN YOUR SURPLUS 1 cs transistors etc into cash immediate settlement We also welcome the opportunity to quote for complete factory clear ance Contact COLES HARDING amp CO 103 South Brink Wisbech Cambs 0945 584188 9509 SEMDLY CAPACITY PRINTED CIRCUIT DOARDS A multi product factory part of a large Company situated in East Lancashire offers capacity for production of printed circuit Production facilities include x Automatic componentinsertion Flow soldering Automatic test equipment x Well equipped laboratory x Quality assurance Procedures x Ametrology department with British Calibration service approval x Delivery performance x Skilled labour force with the personal approach ofasmall highly technical unit The Company combines a high degree of commitmentto meeting delivery schedules with anexcellent reputation for quality which may be to British Defence Standards 05 21 RING IAN GREEN 0254 55241 QUOTING REF EWW WIRELESS WORLD MAY 1984
204. ast technology you have much in common with tre BBC For further details complete and send the coupon to the address below enclosing a large self addressed envelope Please quote reference 84E 4041 The Engineering Recruitment Officer BBC PO Box 2BL London W1A 2BL N Name Address b My qualifications are please tick as appropriate LIHND HNC Electrical Engineering O Higher BTEC Diploma Electronics E Electrical Electronics Degree C amp GFTC 271 Home tel no Age Please quote ref 84 E 4041 in any covering correspondence Weare an equal opportunities employer Pus xp DD engineering Making an Art of Technology T Pioneers of the 805 WIRELESS WORLD MAY 1984 99 WWW americanradiohistorv com Appointments Advanced telecommunications careers with extensive scope at Cheltenham Join the Government Communications Headquarters one of the world s foremost centres for R amp D and produc tion in voice data communications ranging from HF to satellite and their security Some of GCHQ s facilities are unique and there is substantial emphasis on creative solutions for solving complex communications problems using state of the art techniques including computer microprocessoi applications Current opportunities are or Telecommunication Technical Officers Two levels of entry providing two salary scales 6262 8580 amp 8420 9522 Minimum qualific
205. at row Thus access starts well before the full address is in The bus line is naturally physically much bigger than the individual cell which has now been connected to it by acti vation of the row address strobe RAS and so the potential stored inthecellis all but lost on the bus At one point on the bus is a sense amplifier connected back onto the bus lines with positive feedback While is inactive the sense amplifier is held in balance so now even though it has been all but lost the potential delivered by the cell is enough to tilt the amplifier one way or the other Having positive feedback the amplifier pushes the potential on the line heavily in the direction of the input potential putting the line and the cell back to the level in the cell prior to the access There are two implic ations here Firstly that there is a minimum length for the active pulse in that if it goes off beforethe bus line is recharged by the sense amplifier it will discon nect the read cells from their bus lines before they have had a chance to recharge Secondly there is a minimum inactive time for as the sense amplifier is brought back into a state of bal ance These conditions are para mount and to meet them is driven by a monostable i c trig ered by a signal directly from the 80 rather than one which has been combined with others and might therefore be subject to litches caused by timing prob ems between the various consti
206. ates audible most evenings hereabouts are virtually indistinguishable in Style and content a needless duplication which is wasteful both of human effort and spectrum space To replace it they propose a new national pop radio channel possibly for economies of scale even a pan European one This could be distributed by satellite or perhaps as a subscriber on an existing network At the listener s end would be an intelligent receiver designs for which are already at an advanced stage Fitted inside each one would be a speech synthesiser chip which on receipt of encoded cues from the network would fill gaps here and there in the spoken announcements with brief contributions ofits own Equipped with a suitably programmed eprom the device would draw upon a large repertoire of local place names which it could slot into record requests and motoring flashes With a few station ident jingles and the addition of heavy audio compression over all the illusion ofa real local radio station would be complete The idea seems to have something in it for everyone In those underpriviledged regions which don t at present have their own d js listeners would for the price of an eprom be able to feel the sense of local identity now enjoyed by the more fortunate And the former pirates themselves would be spared the hazards of possible prosecution slight though these appear to be Any takers Long queue forthe QL On
207. ation society i Front cover shows first board to be described the processor memory in John Adam s series onthe SC84 micro i NEXT MONTH Computer cassette recorder i A J Ewins describes the control electronics for a solenoid operated cassette deck which can therefore be used in an t I automatic SAVE and LOAD mode commanded from the 8 bit parallel port of a microcomputer Modem Richard Lambley details the design of the WW multi standard modem for which printed boards will be made available Cellular radio A report on the current situation in this up and coming field of communications Current issue price 85p back issues if available 1 06 at Retail and Trade Counter Units 1 amp 2 Bankside Industrial Centre Hopton Street London SE1 Available on microfilm please contact editor By post current issue 1 30 back issues Gfavailable 1 40 orderand payments to EEPSundry Sales Dept Quadrant House The Quadrant Sutton Surrey SM2 5AS Tel 01 661 3378 Editorial amp Advertising offices Quadrant House The Quadrant Sutton Surrey SM2 5AS Telephones Editorial 01 661 3614 Advertising 01 661 3130 See leader page Telex 892084 BISPRSG EEP Subscription rates 1 years 15 UK and 19 outside UK Student rates 1 year 10 UK and 12 70 outside UK Distribution Quadrant House The Quadra
208. ations are TEC SCOTEC in Electronics Telecommunications or a similar discipline or C amp G Part 1 Telecommunications Technicians Certificate or Part plus Maths B Telecommunication Principles B and either Radio Line Transmission B or Computers B or equivalent ONC in Electrical Electronics or Telecommunications En gineering or a CIE Part Pass or formal approved Service technical training Additionally at least four years lower level or seven years higher level appropriate exper ience is essential in either radio communications or radar data computer or similar electronic systems At the lower entry level first line technical supervisory control of technicians involves hands on participation and may involve individual work of a highly technical nature The higher level involves application of technical knowledge and experience to work planning including implementa tion of medium to large scale projects Radio Technicians 5485 7818 To provide all aspects of technical support Promotion prospects are good and linked with active encouragement to acquire further skills and experience Minimum qualifi cations are a TEC Certificate in Telecommunications or equivalent plus two or more years practical experience Cheltenham a handsome Regency town is finely en dowed with cultural sports and other facilities which are equally available in nearby Gloucester Close to some of Britain s most magnificent countryside t
209. ave been constructed using both methods and while a p c b saves time wire wrapping a series of sockets together is recommended as being cheaper and giving a little more flexibility should you not want all of the connectors wired strictly in parallel as would be the case in a daisy chained interrupt system Bus signals are shown in able 1 Pin designations refer to a standard DIN 41612 64 96 con nector i e the type with spacing for three rows of pins but with the middle row missing Power is provided through the outer two pairs of pins at each end of the connector which suits p c b backplanes available from Vero and other manufacturers All sig nals are buffered in and out of the processor board using low power Schottky t t l i cs Processor memory board On this p c b is the Z80 64K bytes of ram system rom and a buffered interface to the rest of the computer The decision to integrate memory with the micro processor was taken as the size WWW americanradiohistorv com by J H Adams SC84 Processor 4 6MHz Z80 processor Maximum 64K byte ram 58K byte ram available using SciDOS Display Up to 32 lines of 96 characters fully programmable Scrolling window determined by software Graphics mode 0 gives 192 by 96 pixels mode 1 gives 192 by 192 resolution Characters and gra phics may be displayed simultane ously Input output Up to four single or double sided 8 5 25 3 5 or 3in disc dri
210. ave enough piel travel to stay on one track for a complete revolution of the drum In this case jumping has to take place on the visible part of the scan and guard band noise between tracks will be played back during the jump There is no disturbance to H sync phase caused by in field track switching because the C format like most other video tape formats is designed such that H pulses on adjacent tracks are aligned This is achieved by choosing a linear tape speed which causes a 3 5 line shift between tracks The half line component removes the effects of interlace on the H V sync rela tionship permitting the horizon tal alignment condition It is this constraint that results in video recorders having rather strange linear tape speeds One revolu tion of the drum now plays back segments of various tracks to build up a field the circum stances under which this happens are beyond the speed range where a broadcast quality signal 1s required and the jumping within the field permits a picture to be seen which is not perfect but is of much more practical use than no picture at all The track following head is in a drum which is of 67 31mm radius and tuming at 3000r p m which means that it is experiencing a pull of about 700 times the force of gravity which tends to keep the Tarok straight Large excursions needed for variable speed opera tion mean that an appreciable drive several hundred volts is needed to overcom
211. ay laser v l s i etching video discs in training hazards cable and stereo tv amplifiers colour coding ELECTRONICS amp lependentelectronics publishing i JUN 2 1 1984 wee eww eee lt we 59 Multi standard modem by R Lambley Introduction to the design SC84 microcomputer by John Adams A new design for engineers and enthusiasts SC84 uses a 6MHz Z80 and has 64K of a universal single chip bytes of ram modem Describes transmission of data by 41 telephone Fibre optic 62 communications f by Brett Wilson information society First of three articles Part 1 deals with optical fibres and waveguide transmission by A E Cawkell A E Cawkell s reappraisal of the interaction between technology and society 59 Variable speed video 69 playback Roots of relativity by J R Watkinson by W A Scott Murray A combination of servo The author of our recent head tracking and digital Heretics Guide draws timebase correction attention to one of allows wide range of Einstein s rare but playback speeds important mistakes Communications G C H Q Cheltenham tv T New products Microcontroller p c b c a d compact direction finder 49 Letters Current dumping 22 Circuit ideas Combination lock universal crystal oscillator simple music synthesizer WWW americanradiohistorv com ee VAR Oei Theintorm
212. ber of input pulses during a known gate period Conversely a period is measured using the period as a gate and counting the number of pulses of a known frequency that occur during the event Both of these measurements may be made using the 8253 by connect ing it according to Fig 3 Coun ters zero and one are set as squarewave generators in mode three and the third counter is set to mode zero for pulse counting In mode zero the counter is preset to a known value usually FFFF is When a positive edge is received thecounter is decremented by the clock until the gate returns to zero The computer can then read the remaining value subtract it from FFFF multiply the result by the clock cycle period and dis play the final result In the case of frequency mea surement counter zero is set to produce 1kHz and counter one to divide this down to 0 5Hz Coun ter three is then gated by the resulting ls positive section of this signal so that frequency may be read directly in hertz The gating period for period and interval measurement will depend on the range required For intervals of say 1s clock pulses of 1kHz would resolve 1ms but for 16Hz 1AMHz Orne ery o LJ LI Ix1ms time base 1s z1stime 16H inet atase CB up i Frequency Period input lt r r7 i mmm eir el FREQUENCY GENERATOR WIRELESS WORLD MAY 1984 intervals of several minutes a 1s clock is more appropriate Sett
213. ble programming in minimum programming times 695 6 carriage ACORN IEEE INTERFACE EPROM ERASERS UV1T Eraser with a built in timer and mains indicator Built in safety interlock to avoid accidental exposure to the harmful UV rays It can handle up to 5 eproms at a time with BOOKS no VAT p amp p 1 Advanced User Guide 2 p amp p 12 95 8 95 Assembly Lang programming on BBC Bic E Shaw pe an average erasing time of about 20 mins ERI 59 2 p amp p eed ies atl aes BBC ieee UV1 as above but without the timer 47 ees 2 p amp p Further Programming on BBC 5 95 introducing BBC Micro 5 95 ind pose PLOTS EDI Programming the BBC 6 50 UV141 as above but with timer 79 30 Hour Basic 5 95 35 Educational Programs 6 95 BBC Sound amp Graphics 7 95 Creating Adventure Programs 6 95 ATTENTION Discovering Machine Code 6 95 A Structured Programming 650 All prices in this double page The Friendly Computer Book BBC 450 spread are subject to change with Beyond Basic BBC 7 25 out notice Large number of other titles stocked CONNECTOR SYSTEMS 86 10 way 150p This IEEE 488 standard interface is a general pur 1n CANNE pose system for exchanging digital data between a 1 D CONNECTORS JUMPER LEADS AMPHENOL RIBBON number of devices in a jocal area The interface Speedblock Type Sem HIGDON Cane weer CONNECTORS CABLE compli
214. boratories San Francisco LA ELECTRIC CHARGE FROM A RADIO WAVE In his letter January 1984 Peter Hesketh gives a step by step method of changing Professor Jennison s apparatus to produce an ideal waveguide bent into a circle I agree with him that no amplifier is in principle necessary to maintain a wave in such a guide and so far his assumptions are completely justified However I do not see how he can use this idealised equipment even in his imagination to support Professor Jennison s contention Is it not truethat the velocity in space of a guided electromagnetic wave is independent of the motion of the conductors that do the guiding In other words even in principle we cannot drive a waveguide backward so that the wave it carries is arrested in space Now this objection does not apply to the discrete component machine described in the article The waves associated with such a machine are not electromagnetic waves in space but as T said in my earlier letter more like the waves we find on a polyphase t ee pRR rml n ume e ln machine As such they have a velocity relative to the hardware ofthe machine Perhaps Mr Hesketh has raised unwittingly a more serious objection to Professor Jennison s demonstration than at first occurred to me We cannot use a machine that generates waves having a velocity which can be vecto
215. bre axis and simp y propagates straight along the axis Ray 2 strikes the fibre at an angle relative to the axis Because the air outside the fibre has an index of refraction of 1 0 whilst the fibre core has a refractive index of about 1 5 the ray is bent toward the fibre axis according to Snell s law of refraction After travelling a short distance along the fibre ray 2 strikes the caveccladding boundary and is refracted again If the angle of incidence at the core claddin interface is sufficiently shallow the ray will totally internally reflect and continue to propagate along the fibre following a zig zag path However if the angle of incidence is too large ray 3 for example the ray will enter the cladding region and ultimately be absorbed by the higher losses in the cladding and jacket Note that the light will still be correctly guided even when the fibre is subject to bending or twisting Obviously under these conditions the zig zag light paths will be somewhat modified The maximum internal angle a ray may have relative to the tibre axis and still be guided is given by Snell s law n 2 and f 2A sing int max Sin 9 a us where n is core refractive index n the cladding refractive index and A the fractional index step n n n Forn 1 5 and A 0 01 then in mx 5 5 corresponding to 9 eyt max 8 1 An equivalent way of escribing a fibre is by way cf its numerical aper
216. carriage 1 50 Ten for 16 carriage 6 Larger discounts for larger quantities Ten thousand valves 1925 to 1975 modern and obsolete types Send 60p refundable VERSATILE BENCH POWER SUPPLY UNITS Contains high quality transformer made to exact ing specifications giving one 20v output and one 20 0 20v output D C output fused at 3 amps but will easily give 5 amps Input AC 110 250v 50 cs Bridge rectification Contained on metal chassis with robust compact case sue 7x5x4 Easily modified to give 40v and 60v Makes ideal variable power supply Usual cos around 60 Our price as new with circuit 8 50 each pp 3 Two units 20 post free XENON FLASHER UNITS Complete panel with dual flash rate slow fast 12v to 18v OC Includes tube base fuseholder 10 metres of connecting wire Full instructions and guarantee As used on police vehicles Ideal for boats and cars Should be 40 each Our price 12 gach pp 150 Two units 23 post free Ideal emer gency beacons for boats and cars DEPT WW MYERS ELECTRONIC DEVICES 12 14 Harper Street Leeds LS2 7EA Tel 452045 WORLD RADIO TV HANDBOOK 1984 ed 12 1984 THE RADIO AMATEUR S H B by A R R L Price 12 50 BEGINNER S GUIDE TO INTE GRATED CIRCUITS by R Sin clair Price 4 50 ELECTRONIC PROTOTYPE CON STRUCTION by S D Kasten Price 15 95 UNDERSTANDING ELECTRONIC SECURITY SYSTEMS by M D Lamont Price 2 30 UNDERSTANDING DIGITAL ELECTRONICS by G McWhorter Price 4 30 INTRODUCTION
217. ccuracy 1 Year Guarantee H 3 e p 3Gate Times 0 5 easy toread L E D Display rs T i sy Iam Adr UU CUT PRICES inc adaptor charger P amp P and VAT gimp HA x METEOR 100 00MHz 104 36 4 4 E S28 tU A Illustrated colour brochure LM M I F ET Aut Bock d Spoon METEOR 600 600MHz 134 26 with technical specification Amer Rer opp METEOR 1000 1GHz 184 36 and prices available on request SG C w DY L2 Designed and BI BLACK STAA LTD Dept WW 9A Crown Street St ives Bake ctured ackakStar Huntingdon Cambs PE17 4EB England CARS mete x5 Tel 0400 62440 Telex 22339 CIRCLE 032 FOR FURTHER DETAILS TOROIDAL METAL FILM RESISTORS TRANSFORMERS 10K 100K i i itish made 89 E24 Hh 12 A i poc Laure p amp p We are now able to offer a range of high quality Toroidal 130R 3 13k 130k inclusive transformers at very competitive prices m 15k on 30VA 6 27 50VA 7 73 80VA 8 51 180R ne 18 180k SPECIAL OFFER 120VA 9 33 160VA 11 43 300VA 15 27 dion 2a zak dt Sofeach 445 resistors Prices include P amp P and VAT 300R s X Sx 1 2 60 Available in the following voltages 6 0 6 9 0 9 12 0 12 15 3608 3x5 36k s 0 15 18 0 18 22 0 22 25 0 25 30 0 30 35 0 35 40 0 40 45 0 DoR ais RR 45 50 0 50 SIOR 50 5 Ms SPECIAL POP PACK Qty discount 50 plus 10 100 plus 20 SOR S6 56k 560k 50 pcs 100
218. ce again Sinclair Research has failed to deliver a product when promised At a champagne breakfast launch at which the QL computer was extensively demonstrated Sir Clive assured us that this time there would be no delays and that the computer would be available to mail order purchasers towards the end of February Unfortunately the production of the QL hit a few snags Bugs have to be eliminated and this has led to the usual delays which could add four or five months to the promised date for delivery By launching a product when it is nearly ready a manufacturer hopes to steal a march on competitors who may also be ready to launch new products Such jumping the gun is not new in the computer industry It has been known for main frame manufacturers to launch an empty box with an impressive Specification and then spend the next few months attempting to meet that specification if sufficient interest is shown by potential customers But in the case of a personal computer like the QL we would have thought it important to have the product ready before launch No doubt when it does come the computer will be as impressive as it seemed to be but the delays lead toa large number of disappointed customers and leaves an impression that we have all been taken in by the undoubted charisma ofSir Clive and that gives the champagne a nasty taste Incidentally has anyone seen a Sinclair miniature flat screen tv rec
219. certainly are reasonably reliable However they do sometimes break down and the involved circuitry around the line timebase diagram can give even experienced servicing engineers a great deal of trouble wasting a lot of time This results in heavy charges for customers to pay Components in the line timebase arethe most highly stressed in the set Even the scanning coils may have a thousand volts across them If instead of the present scan and flyback system we had a zig zag scan scan system the line timebase would be much more wholesome and far less lethal It would be a simple matter to generate the e h t by a separate oscillator and Cockcroft Walton voltage multiplier Synchronizing pulses and most of the other pulses at present supplied by the line output transformer could come straight from an internal crystal controlled waveform generator The crystal frequency and phase would be trimmed by a received frequency burst which also serves as the frame sync signal As tv receivers do not usually last much longer than 15 years I Submit that it is not essential to make the system for the future compatible with anything now in existence Let s start again and this time make it all elegantly simple rational and straightforward for in the end this will save everybody a lot of time trouble and money Many expensive items like colour cameras could probably be sent back to the manufacturers to be refurbished t
220. ch regret that Wireless World announces the death at the age of 77 of Walter Tusting Cocking C Eng MIEE Walter Cocking was first associated with the journal in the early 30s when as a young experimenter he developed a number of wireless circuits He first worked as a freelance experimenter and writer and later he was invited to use the Wireless Worldlaboratory facilities Shortly afterwards he became a full time member of staff In the days before the second world war he established his reputation as a first class engineer with an eye for detail and an ability to convey his developments in a concise and easy to understand manner Beforethe existence of an electronics industry and supporting component Interactive video discs for unioneducation It can t be very often that a trades union gets a pat on the back from a Conservative minister Such howeveris the case when the Electrician s Trades Union installed an interactive video disc player in their Union Training College at Cudham The system is to be used to train union members in microelectronic technology and the system is to be developed jointly by the union and Epic Industrial Communications with the Department of Industry providing two thirds of the 150 000 costs The union and Epic will provide the balance and will market the system to industry and training institutions next year At the announcement of the project Kenneth Baker Minister for Inf
221. ck from the bimorph A break is formed in the electrodes on the surface of the bimorph which apply the electric field for delfection and the small strip of electrode which is isolated in this way becomes a sense strip which generates a deflection sig nal used for damping and for feed back during the vertical interval when the head is out of contact with the tape If the capstan of the v t r is made to run slightly slow the drum speed will not change because it determines the field rate Thus the tracking servo will cause the bimorph to bend further and further down the drums as it attempts to follow tracks which are not passing quickly enough Conversely if the v t r runs slightly fast the bimorph will bend further and further up the drum to follow tracks which are passing too quickly In both cases if nothing were done the bimorph would eventually run out of travel To allow continuous operation it is necessary to make the tracking head jump as it crosses the base of the omega reducing the bimorph travel When running slow the jump will be one track back such that from time to time one field is played twice to maintain field rate whereas when running fast the jump will cause a tape field to be missed periodically The more the speed differs from unity the more often will such jumps be necessary Figure 6 shows several examples of jumping and also shows the drive signal which will be sent to the bimorph neg
222. clearing the open line on X activation to keep the lock engaged The change of state in Error inhibits the sequence counter IC through setting of IC and activates a Yo Hz multivibrator IC with a duty cycle of 30s Also the delay counter is incremented by one and its contents loaded into counter IC which holds the control sequence for the specified delay steps after this the borrow output goes low clearing IC and allowing sequence counter IC to continue At the end of each control sequence mutlivibrator IC is WIRELESS WORLD MAY 1984 disabled and IC clears inhibiting sequence decoder IC and the sequence counter IC A further Enter signal restarts the control sequencer permitting another trial entry Upon activation of Open delay counter IC and the sequence counter IC resets Note that the MCK generator not shown can be realized with a 74123 as shown in the delay section or with an NE555 timer G A M Labib Heliopolis Cairo Keyboard Hexadecimal Combination size straps o p g g2 D t or orem O m m t Entry enabled WIRELESS WORLD MAY 1984 53 WWW americanradiohistorv com CIRCUIT IDEAS Universal crystal oscillator Design of a universal crystal oscillator is hampered by the wide variation in crystal parameters series resistance of low frequency crystals can be more than 200 times that of h f
223. comes obvious and the acoustic of the original environment comes through to the listening room The Minim decoders also provide enhanced results from conventional stereo material We can now supply UHJ encoded records tapes and compact discs And don t forget our other products PROGRAMMABLE WEEKLY TIME SWITCHES TELEVISION SOUND TUNERS Please send me information on Timeswitches Television Tuners Ambisonics Name Address Burnham Slough SL1 7NY Tel Burnham 63724 wws CIRCLE 080 FOR FURTHER DETAILS 22 HENRY S sure OPEN 6 DAYS A WEEK ORDER BY POST OR PHONE CALL IN AND SEE FOR YOURSELF SOFTWARE PERIPHERALS e MULTI BOARDS 80 BUS MULTI BOARDS BUILD A CUSTOM SYSTEM FROM SCRATCH or expand your GALAXY or NASCOM Demonstrations lor callers 125 00 195 00 145 00 225 00 140 00 125 00 85 00 GMB11 CPU GM832 SVC GM829 FOC SAS GMB13 CPU 64K RAM EV814 IEEE 488 CONTROLLER GM802 64K DYNAMIC RAM GMB27 B7 KEY KEYBOARD GMB39 PROTOTYPING 12 50 MP826 STATIC RAM 185 00 GM816 MULTI I 0 125 00 IO 828A SUPER PLUTO COLOUR GRAPHICS PROCESSOR 192K RAM GM833 AAM DISK 512K UK C P amp export extra at cost ALSO IN STOCK MOTHER BOAROS FRAMES CABLES POWER SUPPLIES KEYBOARDS SOFTWARE etc FULL LEAFLETS DETAILS OF SUITABLE PERMUTATIONS SENO LARGE SAE We can advise also with terminals and complete to use SOFTWARE MOIS C INTELLIGENT DISASSEMBLER For all CP M based
224. cs on to a single substrate Mounted in single in line packages these Texas memory arrays are available in several configurations including 64K by 4 5 8or9 bits as wellasa device organized as a 256K by S one bit memory Leadless chip v carriers are bonded directly to vertically the devices offer considerable saving in board space and in board complexity and assembly time The rams require a single 5V supply and have an access time of 150ns They are refreshed 256 times every 4ms and have a protective coating against alpha particle intrusion which can cause errors Available from Jermyn Distribution Vestry Estate Sevenoaks Kent WW 208 CUSTOM POWER SUPPLIES A small projects division set up by Grenson Electronics was able to win a large contract by designing and providing prototype switch mode power supplies in five days Although they cannot guarantee to be so fast every time they say that they are geared up to the rapid design and construction of prototypes They achieve this by separating this division from the main manufacturing of production units Grenson Electronics Ltd High March Daventry Northants NN11 4HQ WW 209 TRANSIENT PROTECTORS A range of power line and data line protectors incorporate TransZorb silicon junction transient suppressors Mains born transients can induce computer breakdowns and signal line interference may not be immediately detected but can cause downgrading of pe
225. ct it is necessary to give the head an approximation to parallel motion by combining two bimorphs whose bending tend encies will then cancel An a c component of between 400 and 700Hz is added to the bimorph drive which causes the head to execute an approximate sinusoid One field scan contains many cy cles of dither The effect of the dither on the r f envelope as shown in Fig 4 is an amplitude modulation of the carrier which has little effect on the video owing to the insensitivity of the f m system to amplitude var iations Figure 4 a shows that the effect of the dither on a cor rectly aligned head is a dither fre quency doubling in the r f enve lope Figures 4 b and c show the effect of the head off track Both examples appear similar but the phase of the envelope modulation is determined by the sense of the tracking error In Fig 5 the r f is detected to obtain a level which is fed to a phase sensitive rectifier whose reference is the dither drive sig nal The output of the phase sen sitive rectifier is a tracking error signal which contains both mag nitude and sense This tracking error is fed back to the bimorph drive circuit to cancel the error As the track following head and the bimorph form a mechani cal resonant system the reson ance must be above the frequen cies used in operation and damp ing is required This is provided WWW americanradiohistorv com by positional feedba
226. cting electrom agnetic theory rather than go on indefinitely riding roughshod over ordinary mechanics and common sense People working along these lines have made substantial prog ress recently for example Profes sor Richard Waldron of the Ulster Polytechnic It may be that only one or two more good new ideas are needed in order to clear up this mystery which dates back nearly a century to Michelson and Morley If at long last we could get the foundation of electrom agnetic theory right we could take a deep breath and make a start on tidying up the mess WIRELESS WORLD MAY 1984 performance reliability value and immediate delivery Hitachi Oscilloscopes provide the quality and performance that you d expect from such a famous name with a newly extended range that repre sents the best value for money available anywhere Hitachi Oscilloscopes V 212 20MHz Dual Trace V 209 20MHz Mini Portable V 222 20MHz illustrated V 509 50MHz Mini Portable V 203F 20MHz Sweep Delay V 1050F 100MHz Quad Trace V 353F 35MHz Sweep Delay V 134 10MHz Tube Storage V 422 40M Hz Dual Trace VC 6015 10M Hz Digital V 650F 60MHz Dual Timebase VC 6041 40MHz Digital Prices start at around 300 plus vat including 2 probes and 2 year warranty We hold the range in stock for immediate delivery For colour brochure giving specifications and prices ring 0480 63570 Thurlhs Reltech 46 High Street Solihull W Midlands B91 3TB CIRCLE
227. d then the buzzer sounds 27 py sotuansary eoey Dy D 1N4001 1N4001 Ski T Charger 9V Ni Cd input NI 1N4001 1N 4001 Fig 2 Complete circuit of Pausaid R and R are miniature multi turn presets Sensitivity control R should be adjusted so that the led flashes whenever the patient talks PAUSAID SENSITIVITY and not for everyday communica tion there is no need to conceal It Operation of the aid is centred on a capacitor which charges up as the patient speaks and dis charges during pauses If the charge exceeds a preset threshold a buzzer is triggered The design is based upon an LM324 quad op amp One sec tion IC forms a microphone amplifier with a gain of about 50 Its input is clamped by D and D to prevent damage should the bat tery charger be plugged into the wrong socket IC is arranged as Fi a variable gain amplifier with a maximum gain of 100 controlled by the preset resistor R A peak hold DU is provided by D R and C is used as a com parator its ae voltage sup plied by R and Rj The talk without pause time limit is fixed by Dj Rz Ry and C pauses necessary to prevent triggering of the buzzer e d mined by Dg R Rig and sets the hysteresis for the NT trigger IC which drives the con trol input of the buzzer directly D resets the circuit and prevents unwanted feedback WWW americanracdiohistorv com D7 ee Using Paus
228. de band to 10MHz MARCONI TF2603 Frequency range 50kHz 1 5GHz High Sensitivity from 300uV MARCONI TF2604 Electronic Multi meter AC DC 300mV Full scale to 300V 1kV DC Re sistance ranged AC Frequency range 20Hz 1500MHz X CONSTANT VOLTAGE TRANSFORMERS wr xr ADVANCE VOLSTAT Type Model MT140A Mains input 190 260V AC Output 230V AC 150W Price each 20 VAT 2 carriage ROHDE amp SCHWARZ SDR AM Signa Generator 0 3 1GHz TEKTRONIX 2901 Time mark Generator ROHDE amp SCHWARZ Resonance Frequency Meter 470MHz 2 5GHz TELONIC SM2000 with 500 900MHz plug in 175 4051 Graphic System compatible P F RALFE ELECTRONICS 10 CHAPEL STREET LONDON NW1 TEKTRONIX 453 Dual trace 50MHz TELEQUIPMENT D75 Dual trace 50MHz portable 450 HEWLETT PACKARD 1707A Duai trace 75MHz TRIO CS1575 5MHz Dual trace 250 MARCONI TF1245 Q Meter MARCONI TF 1313 1 4 LCR Bridge MARCONI TF868 LCR Bridge MARCONI TF2604 Electronic Multi Meter MARCONI TF893A Audio Power Meters 85 MARCONI TF2502 RF Power Meters DC 1GHz 10w fsd 350 MARCONI TF2701 In Situ Universal Com ponent Bridge 250 HEWLETT PACKARD 3450A Muiti Function Digital Multi Meter ROHDE amp SCHWARZ Polyscop SWOBII METROHM 500V insulation Testers Transistorised 40 pp 1 50 BRUEL amp KJAER Heterodyne Voltmeter 0 5 240MHz AIRMEC Display Oscilloscope 279 4 trace 14x10 CRT 195 RIKADENKI 3 channel Chart Recorder Model B 3
229. e been used for discrete compo nents details of which appear with each circuit diagram John Adams next article describes SC84 s input output o Jucor 1343 229 2949298808 3 3 0 0702 2 GILa TUT Wa diee ES Nye a fi oard SciDOS with utility soft ware extended Basic with gra phics facilities and Basic with enhanced file manipulation i o control numeric constant string handling and 12 digit precision are available for 36 22 50 and 31 50 respectively These prices include vat and postage and become 24 15 and 21 respectively for non commercial users Further discounts are available for those buying more than one software package at once Write enclosing s a e to J H Adams 5 The Close Rad lett Herts A set of three Eurocard for mat plated through hole boards for SC84 is available from Combe Martin Electronics King Street Combe Martin Devon EX34 OAD Price is 39 for the set including v a t and inland or overseas postage John Adams is considering producing a kit of arts for these boards and John odson secretary of the Scien tific Computer User Group is organizing the SC84 user group For further information send an s a e to John Adams for kit details orJohn Hodson 189 Trent Valley Road Oakhill Stoke on Trent ST4 5LE for user group details WWww americanradiohistorv com SS 2 51 DONT T WASTE GOOD IDEAS We prefer circuit ideas with neat drawi
230. e field work will be unsupervised Qualifications ONC HNC or equivalent technical training combined with a sound practical electronics background in digital and or analogue cir cuiting The understanding of microprocessor systems with the ability to maintain low level software is an advantage Academically well qualified younger applicants but with limited practical experience will be consid ered and relevant necessary training will be given Salary Dependant on qualifications and experience in the scale 6483 7552 p a Professional and Technology Officer Grade IV The vacancies are at Professional and Technology Officer grade IV for period appointments of 3 years Applicants should be physically fit and must be male as field work requires successfu candidates to share tented accommodation and to live in premises provided by the British Antarctic Survey which are only equipped for male accommodation For further details and an application form please write to The Establishment Officer British Antarctic Survey High Cross Madingley Road Cambridge CB3 OET Please quote Ref BAS 14 Closing date 9 May 1984 een t t t t e ARTICLES FOR SALE Electronic Opportunities 6 000 18 000 p a j SPEAKERS i x Microwave Design MOSTLY UNDER HALF PRICE Sales PEERLESS Test and Commissioning TWEETER 94mm DIAM 1 SOFT DOME ATE Applications 50 watts 4 65 PP 50p x Field Service SEAS f Many of our clients in the S E
231. e noticeable The consumer electronics industry assumes that very few of its products will ever be used in places subject to high levels of r f despite the many thousands of broadcast amateur radio c b transmitters cordless telephones two way car radios etc The latest problem is arising from the new telephone handsets and inserts that replace the traditional carbon granule microphone with an electret transducer and integrated circuit amplifier As fitted these telephones appear to be most susceptible to local transmitters yet there is evidence that this can often be much reduced by improved r f bypassing sometimes by utilizing components already fitted The RSGB reports that the interference to amateurs using the 144 MHz band at Milton Keynes has been traced by DTI to radiation by and feed through at the British Telecom cable frequency translation units at about 120 points in the cable area where a television channel centred on 143 MHz is changed to u h f for final distribution into homes No significant leakage has been traced to the main buried distribution cable Each translation unit feeds about 50 homes The problem does not anse with translation units built in metal cabinets but only where these are contained in fibreglass cabinets where filters have to be fitted The DTI measured high levels of radiation at distances up to 100 metres from the translation units DTI have stated that the local Radio Inter
232. e with outputs of 0 60V 12A 0 120V 6A 0 240V 3A SEND FOR FURTHER DETAILS OF THESE VERSATILE be Valnadiec POWER LIMITED A K INTERNATIONAL BUILDING LAWRENCE ESTATE GREEN LANE HOUNSLOW MIDDX TW4 6DU ENGLAND 01 570 5622 CIRCLE 030 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 a selection from our huge stocks All items reconditioned unless otherwis stated DEC 11 70 SYSTEMS 11 70 CPU Dual Rack Cabinet 1MB MOS Memory 2 x AMO3 Disk Drives DHTTAD Multiplexor LA120 Console 55 000 DEC 11 34 SYSTEMS 11 34A CPU 1012 Chassis 256KB MOS Cabinet 2 x AKO Disk Drives 021A Multiplexor VT100 Console lc ee DEC 11 23 SYSTEMS 11 23AB CPU 5 a Chassis 128KB MOS Memory DUJ 4 line Interface RXV 1 Dual Floppy Disk Drive Cabinet VT100 Console 10 250 5 795 DEC11 03 SYSTEMS 11 03N CPU 5 Chassis 64KB MOS Memory DLV11 Serial Interface AXV11 Dual Floppy Disk Drive Cabinet LA36 Console 3 500 DEC DISK DRIVES RKOSF SMB fixed 695 RK05J 2 5MB 975 RK06 14MB 750 RK07 28MB 1 500 RlW22 RLO2 and 11 23 cti NEW 4 500 RM02 67MB 5 750 DEXEO Europo ensington Exhibition Centre AMOS 256MB 14 500 RX11 RXV Range of Controllers also available DEC MODULES HUGE STOCKS OF DPTION MODULES FOR VAX UNIBUS QBUS ANO OMNIBUS DEC TERMINAL OFFER Fully Reconditioned Units covered by 90 days parts amp labour warranty LA36 30cps KSR Ter
233. e Density Interface can be supplied with any of the disc drives listed below And it is not available any where else except Opus To place your order post the coupon or buy direct at our showroom OPUS 3 MICRODRIVE Double Sided 40 Track Drive 1 2 Megabyte Unformatted e Twice the capacity on line ofother available drives e 200K Single Density 400K Double Density Ex stock delivery 3 ms access time e Lowest power consumption direct drive Includes case leads and utilities disc e Totally compatible with 514 drives Single Drive 229 95 Dual Drive 459 95 514 JAPANESE DISC DRIVES SINGLE DRIVE Opus 5401 Single Sided 40 Track 250K Unformatted Formatted 100K Single Density 200K Double Density ____ 179 95 Opus 5402 Double Sided 40 Track 500K Unformatted Formatted 200K SingleDensity 400K Double Density 229 95 Opus 5800 Double Sided 80 40 Track 1 Megabyte Unformatted Formatted 400K Single Density 800K Double Density 259 95 Opus 5802 Double Sided 80 Track 1 Megabyte EA Unformatted Formatted 400K Single Density 800K Double Density 299 95 Switchable 80 40 Track e Height Includescase leadsand utilities disc DUAL DRIVES All Dual Drives are metal cased with separate power supply Opus Dual 5401D Single Sided 40 Track 200K 400K on line amp 379 50 Opus Dual 5402D Doubled Sided 40 Track 400K 800K on line 459 95 Opus Dual 5800D Double Sided 80 40 Trac
234. e RC combination between the first two buffers so that the falling edge at the second output is somewhat later than that of MREQ This signalis used to switch addresses being sup plied to ram through multiplexers IC o Further delay is applied to produce CAS To provide a quick end to the memory access so that the multiplexers are definitely reset to the row address position ready for a refresh cycle a diode shunts the first time delay which would follow MREQ trailing rising edge Refresh occurs when MR cycles while the RFSH signalis active During this periog the Z80 puts out a seven it value from a special internal register which increments after every refresh M triggers the monostable i c to set off a RA cycle but the R signal inhibits production of address multiplex or CAS signals From the previ ous discussion of dynamic mem ory operation one can see that the sole result of the RFSH cycle or any memory cycle during which MEMDIS or ROMEN is active is to refresh 1 128th of the memory A simple inverter ring pro duces the system clock The crystal frequency will depend on the microprocessor used i e 4MHz for the Z80A or 6MHz for the Z80B A Z80A should work with a popular 4 1943MHz crys tal These are relatively cheap and although the MK3880 4 or Z80A CPU is only specified up to 4MHz it is unlikely that they will not work at this slightly higher frequency Each i o section has its own cry
235. e RMS measurements on AC voltage current extended 4 digit capability dB relative reference and much much more Contact Electronic Brokers today for the full facts on this amazing new multimeter VAT Complete with Batteries Also available without Luminescent Display at 165 VAT Electronic Brokers Ltd 61 65 Kings ers Cross Road London WC1X 9LN Tel 01 833 1166 Telex 298694 P di d E oe um Bde Ende edem D jalterertcoyetions ce 2 0 Bim eda em E em A copy of our trading conditions can be supplied on request CUBE JOBBER the industrial computer The CUBE Jobber is not so mucha specific computer but more an example of what can be done with the CUBE range of computer modules as illustrated Choice of 6809 or 6502 processors BBC BASIC option on 6502 8 KB of battery backed RAM fitted Up to 64KB RAM optional expansion JUGO 24 column impact printer pda ex VAT 24 character x 2 row liquid crystal display Centronics printer port Send for free E i LILI 25 position keyboard supplied blank white F catalogue to L 19 enclosed rack with power supply _ RS 422 423 serial port 20 channel digital port Control Universal Ltd Alternatively other modules from the CUBE rangecan be fitted Anderson s Court d including video memory EPROM programming floppy disk aaa p m p TEE iur i i ambridge digital and serial i o analog interface micro development aids Te
236. e the overall stiffness of the bimorph As drive in a conventional feedback servo is proportional to the loop error the tracking error would be grea ter at the excursion limits This problem can be eliminated by using a feedforward technique For any linear tape speed it is possible to calculate the slope of the voltage ramp needed to keep the head on track by geometry Figures 6 7 and 8 show that the slope is proportional to the devia t on from normal speed i e slope is zero at 1X and the slope at 3X is equal and oppo site to the slope at 1X The cap stan drive circuit can determine the speed deviation and if this is fed into an integrator which resets once per drum revolution a pre dicted deflection signal can be WIRELESS WORLD MAY 1984 M a M E L ASS X aeque E E mmu PRETIUM ELA E E EE Fig 5 Phase sensitive rectifier in a extracts tracking error from r f envelope Position feedback from sense strip provides damping At b break in Dither generator Bimorph driver electrode plating isolates Tracking sense strip on bimorph head isolating two sections of dE element which bend in opposition due to cross wire connections Cas rf ad PMID preamplitier rectifier f m to video discriminator Fig 6 Tape at a moving at 125 normal speed to maintain field rate four out of every five tracks are played with single track jump every four Slope of
237. e type of of working environment most suited to your career plans The Recruitment Officer HMGCC Hanslope Park Buckinghamshire MK19 7BH T pn ata m A v Yor Iy oe SSS D MA b 4 AN X SEFEFEF M Marconi Communication Systems world leaders in the design manufacture and installation of advanced electronic communications equip ment and systems require experienced field staff Contract employment North Africa and Middle East Maintenance of HF or Tropo LOS MUX and associated equipment We offer excellent salaries living allowances and overseas benefits where applicable Skilled and dedicated Engineers and Technicians seeking permanent employment will find excellent scope for career advancement within our highly successful company extension 498 Communication Systems SMW TT E SB ic f 77 una a Saal m nly N Please telephone for an application form or send a full c v to Gordon Short Marconi Communication Systems Limited New Street Chelmsford Essex CM1 1PL Telephone Chelmsford 0245 353221 1 psy h 4 5 ZA d Ln E M ui M Demanding assignments await adventurous Engineers Technicians with an electronics quali fication or HM Forces training and a minimum of three years relevant experience current UK driving licence required as follows Permanent employment Worldwide Installation and Ma
238. ection allows playback of broadcast standard video over a wide speed range C format is a helical scan sys tem using an omega wrap around the drum as in the sketch head on the drum traces a diagonal track across the tape where one drum revolution corresponds to one video field Because of the open base of the omega the head will be out of contact with the tape for a short period once every revolution which is timed to coincide with the vertical sync pulse where there is no visible picture information Vertical interval sync pulses can be easily taken from reference signals and for this reason stor ing the vertical interval 1s optional under C format Where vertical sync storage is implemented a second sync only head posi tioned 30 behind the video head records in an area between the control and Audio 3 tracks If ver tical sync recording is not imple mented a dummy head replaces the sync head and a further audio track is available in the area vacated by the sync information Figure 1 shows the resultant pattern on the tape and includes the linear audio and control tracks the drum turns against the direction of tape travel and the video head to tape velocity is the vector sum of the drum peripheral velocity and the linear tape veloc ity Similarly the angle of the tape tracks is a function of the drum omes and the tape speed uring playback the capstan and drum servos must phase lock to an ext
239. ed system then Nyquist s sampling theory suggests that there will be no information above one half the dither frequency It is essential to filter the tracking error to prevent aliasing compo nents dione the feedback The presence of a low pass filter in a feedback loop is undesirable in a servo system since the overall response cannot exceed the response of that filter without instability One approach is to use a comb filter in conjunction with a care fully chosen dither frequency Figure 9 b shows that the har monics of the tracking error are at multiples of 50Hz the drum speed If the dither frequency is set between multiples of 50Hz the sampling spectrum will inter leave the base spectrum A comb filter with peaks at 50 100 150Hz etc can recover the track ing error and reject the aliasing components giving the highest possible response rate for a given dither frequency Clear an NTSC machine with 60Hz drum rate will need a different dither frequency he mechanism of track fol lowing has been discussed but this can only function if it is cor rectly coordinated with jumping control To reduce jerkiness in the picture the jumps should be as small as possible which implies that they will be as fre quent as possible The smallest jump possible is one track and to give broadcastable pictures the jump can only occur at the vertical interval From stationary to 2 single track jumps are suf ficient their fr
240. eference to the embank ment are not simultaneous with respect to the train and vice versa relativity of simultaniety Every reference body co ordinate sys tem has its own particular time unless we are told the reference body to which the statement of time refers there is no meaning in a statement of the time of an event Let us now without passion ana lyse that remarkable argument by which Einstein sought to justify both his assumption of the con stancy of c and the consequent dilation of time Here we find his observer M hastening towards the beam of light coming from B while riding on ahead of the beam of light coming from A But at the instant when the flashes occur the position of M coincides with M by scenario see above so at that instant the distance A gt M is equal to the distance B M in exactly the same way that the dis tance A M is equal to the dis tance B gt M Therefore if the velocity of light is the same for everyone as assumed in the the ory its time of passage from A to M must be the same as its time of passage from B to M exactly as it 1s over the equal distances AM and BM Hence the light from both sources must reach M at the same time just as the light from both sources reaches M at the same time But this is precisely the condition which Einstein him self has so carefully defined as si multaneous pa Wa md a ww Situation at the track
241. eived signal If the signal fades the reading is held Various operating modes give different selections of sampling and holding signals The averaging time can be altered by acontrol but the processor control always ensures that the briefest signal will give an accurate bearing whatever the setting The unit may be used in conjunction with a separate receiver or may have a receiver incorporated into it The coaxial feeder from the head unit also act asad c power cable to 78 the head unit Although the system is designed to work with f m signals it will also operate with a m ors s b signals which it will interpret as n b f m Other refinements include an offset so that the antennae especially on a mobile unit do not have to be accurately aligned since any misalignment can be compensated It is even possible to reverse the directions entirely so that the system can be used with upside down antennae under an aircraft for example Suitable antennae receivers and all ancillary equipment can be obtained from the Manufacturer Datong Electronics Ltd Spence Mills Mill Lane Bramley Leeds LS13 3HE WW 211 ae K ts P ae i nde A EE f x amp MORE ON VISION The MicroEye system for the BBC Computer has now been enhanced by the addition of two software packages The standard MicroSight software will calculate areas and perimeters of an image and can be accessed from the Basic system The additions
242. eiver its what the wireless world s The IC R71E latest HF receiver from ICOM with remote control ID C o Electronics 143 Reculver Road Herne Bay Kent England CIRCLE 040 FOR FURTHER DETAILS UNISELECTORS TYPE 2 SERIES Uniselectors are designed to meet the requirements for mechanisms having long life and dependability They are approved by British Telecom and used extensively by them Uniselectors can be supplied with double ended wipers giving two appearances of 25 points per revo lution 4 6 8 10 and 12 level uniselectors can also be supplied with single ended wipers connected in adja cent pairs which give 2 3 4 5 and 6 complete circuits of 50 points per revolution respectively Wipers may be bridging or non bridging and can be adjusted for position on bank contacts independently of mechan ism adjustments Also in stock Miniature Uniselectors 3000 Type Re lays Carpenter Polarised Relays High Speed Relays Transformers 2000 and 4000 Type Selector Mechan isms etc As one of the few remaining suppliers of Strowger components in the U K we would welcome your enquiries and look forward to discussing your needs Cynpex Ltd Telecommunication component factors Unit 3 Argyle Way Stevenage erttordshire SG1 2AD Telephone 0438 352497 352326 Telex 825617 CIRCLE 051 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 A WWW americanradiohistorv com uu MEE qe acre T
243. eivers Also it may be setto give an audible indication of low level infra red radiation using the analogue loudspeaker out put or the digital buzzer output with a length of optical cable acting as a probe TRANSMISSION EQUIPMENT for both analogue and digital data over free space as well as optical fibres t is also ideal for TRAINING engineers technicians and executives in the growing field of fibre optics Suitable for industry colleges and technology training centres The Fibre Optics Educator comprises fully portable optical transmitter and receiver units optical cables together with numerous accessories a comprehensive manual and carrying case Designed and Manufactured in the U K ELLMAX ELECTRONICS For further details contact ELLMAX Electronics Ltd Unit 29 Leyton Business Centre Etloe Road Leyton London E10 7BT Tel 01 539 0136 CIRCLE 031 FOR FURTHER DETAILS If an advertisement is wrong were here to put it right If you see an advertisement in the press in print on posters or in the cinema which you find unacceptable write to us at the address below The Advertising Standards Authority ASA Ltd Dept 3 Brook House Torrington Place London WCIE 7HN AMBISONIC SURROUND SOUND DECODERS Ambisonic surround sound gives a realism in the reproduction of music that is hard to describe without using hackneyed expressions like natural and being there Positioning of the performer be
244. elioration of rural conditions by improving the social environment Such improvements come not only from improved living conditions but also from reducing the feeling of isolation felt by many rural inhabitants Communications channels also work the other way and can inform urban dwellers of the conditions in the country and perhaps give them the will to improve them Other spin offs include improvements in conservation and better use of energy in reduced transportation costs through the provision of telecommunications for example WIRELESS WORLD MAY 1984 Optical fibre cables and satellite links will further improve rural communications On the subject of the use of satellites Mr Butler maintains that at present they are chiefly used for high capacity trunk circuits which could probably be better served by ground based links and relays especially high capacity digital fibre optic trunk lines including trans oceanic links Over the long term he says there are only three major areas that will always be better served by satellite communications than by any other means aircraft ships and rural areas Satellite communications are by their very nature distributed It is much more economical to install an earth station ina rural community than to lay down a cable and one or a few channels in each village is much better than large numbers of facilities in fewer locations the advantages of such satellite communications
245. elopment of a wide range of non electronic clinical equipment mainly in theatres and special care units in hospitals throughout the Plymouth Health District Hospital experience is not essential as further training will be given HNC ONC City and Guilds Final certificate or equivalent qualification is required The work involves occasional travel and necessitates a current driving licence There is a requirement to be prepared to participate in a scheme to provide out of hours emergency cover Posts are offered in one of the following grades according to relevant experience MPT IV 5171 6 798 per annum or MPT III 6 132 7 926 For further information Post A Contact Mr A Dawson 0752 834276 Post B Contact Mr Bartrip0752 834279 Applications forms available from and returnable to Unit Personnel Officer 1 Belvedere Greenbank Rd Plymouth Please enclose a s a e Closing date 4th May 1984 SATELLITE RECEPTION RESEARCH ASSISTANTS For the BBC s Monitoring Service at Caversham near Reading Berkshire With the advent of satellite communications broadcasting and news agency organisations are switching from conventional means to satellites for their transmissions Satellite Reception Research Assist ants will be involved in the Monitoring Service s work in this field Duties include frequency scanning and the compilation of transmission schedules Extensive experience in communications with C and G Intermediate Te
246. en Chief of Defence Staff Admiral Sir Terence now Lord Lewin to agree that HMS Conqueror should sink the Argentine cruiser General Belgrano The hostility of the Services to Intelligence activities over which they have no direct control by people not subject to Service discipline and traditions is of long standing particularly in the field of Sigint It dates back at least to the period following World War 1 when the Navy s cipher cracking operation passed from Room 40 at the Admiralty to the Foreign Office controlled Government Code amp Cipher School It was reflected during World War 2 in the refusal of the Admiralty to agree to Ultra intelligence being distributed to the Navy by MI6 s Special Communication Units as for 47 Y rrr Army and RAF Commands Viewed in this light the GCHQ fracas emerges as part of the old struggle between a Navy dominated Ministry of Defence and the civil departments of Government including the Foreign and Commonwealth Office a view supported by later reports of political vetting at MoD Hereandthere In many major urban centres in the USA broadcast listening on f m is now significantly ahead of a m with the Dallas Fort Worth area showing f m with a 69 4 per cent share of listening A few major urban centres including San Francisco still remain a m orientated The a m broadcasters hope to win back listeners with a m stereo Meanwhile the f m broadcaste
247. entific infor mation for terminal connected users The private networks shown in Fig 1 are composed of lines leased from the s for inter connecting the different sites of an organisation within a country or may be to provide intra organi sation services for large compan ies such as Unilever airlines etc requiring international satellite or cable links The commercial networks in ig 1 refer mainly to the Value Added Networks VANs deve loped by private telecommunica tion companies in consequence of deregulation in the United States to offer special services using lines leased from AT amp T or using satellite or terrestrial mic rowave communications Some private companies have been accorded the status of common carrriers meaning that they are ermitted simply to carry traffic or others without having to qual ity as VANs Some companies have nodes that is connection points in Europe and elsewhere If these three kinds of network were interconnected so that any service available on any of them was available to all in such a way that there appeared to be a single network then a big step towards universal communications would have been made The critical mass of customers needed to encourage more services would appear the system would grow costs would fall and home ser vices would become viable There are some technical problems to overcome but the main obstacles to this kind of com
248. ently TE WWW americanracdiohistorv com WIRELESS WORLD MAY 1984 et bee M d S World Telecommunications day Telecommunications Expanding Horizons is the theme chosen by the International Telecommunications Union for the 16th World Telecommunications Day to be held on 17th May The day marks the foundation of the ITU which is now 119 years old Inhis annual message Richard E Butler Secretary General of the ITU praised the success of World Communications Year 1983 which combined many of the abilities of operators manufacturers and users of telecom systems and pointed out that many nations were retaining their national committees set up for WCY so that the work may be continued The improvement of communications in under developed countries has been a particular concern for the Union as it is believed that telecommunications can play a key role in development Mr Butler points out that 90 of all services are confined to about 15 of the world s nations Studies carried out by the ITU and the OECD have shown that rural communities which had been steadily dwindling could remain viable if they had the means of communication This does not only apply to the Third World poorer parts of the United States became more prosperous when telephone services were installed under the Rural Electrification Administration instituted nearly 40 years ago Telecommunications can contribute to the am
249. eparator giving simulator wood effect clipped between the two keyboards Manufactured overall dimensions width 1 027mm height 131mm front and back 361mm keyboard separator approx 1 094mm 202 50 for 5 372 50 for 10 838 35 for 25 1 545 35 for 50 Sample sent 45 4 P amp P 56 35 inc VAT ORGANPEDALBOARD A highquality 13 note C to C pedalboard Notes are manufactured in ahard wearing plastic covering steel levers Contact switch fitted to each pedal unit 380mm x 250mm 108 for 5 198 for 10 822 for 50 1 513 for 100 Sample sent for 24 4 P amp P 32 50 inc VAT SWELL PEDAL incorporating the latest technology Volume controlled by photoelectric cell Designed to be mounted in a console Detachable metal mounting plaie with roller stop for easy installation Size 250mm x 120mm matt black finish 56 25 for 5 103 50 for 10 238 for 25 428 20 for 50 788 for 100 Sample sent 12 50 4 P amp P 18 98 inc V A T TERMS C W O Please add 5 to all orders for carriage by 15 V A T Export enquiries welcome We find it impossible to advertise ail we stock Please telephone or write for further enquiries Personal call ers always weicome SPRINGFIELD HOUSE TYSSEN STREET LONDON E 8 TELEPHONE 01 249 5217 TELEX 9853906 EECO G Eircom Eourwenr Co CIRCLE 083 FOR FURTHER DETAILS AC DC Electronic Components Price 0 20 BIG VALUE RESISTOR PACKS Device Watt Carbon Film 1r 10mg
250. equency varying from never at 1X to once per rev at 2X where every other field is played back This varia tion in jump rate is infinite and therefore it 1s not easy to calculate when to jump by processing the tape speed From 0 to 2X a single track jump will be made if the bimorph displacement exceeds 1 2track at the end of a field This will cause the bimorph displacement to become half a track the other way and if that tape speed is maintained the error will return to zero over a number of fields and build up to half a track again causing a fur ther jump To be continued WIRELESS WORLD MAY 1984 MULTI STANDARD MODEM Multi standard modem Suitable for any computer with an RS232 type serial port Until fairly recently the average electronics hobbyist would have had little use for a modem But now the situation has changed considerably with the emergence of a multitude of dial up informa tion services accessible to anyone with a suitable home computer One of the very biggest data bases British Telecom s Prestel can be reached from most parts of the country for the price of a local telephone call Besides well publicised services such as home anking and teleshopping Prestel includes thousands of pages for microcomputer users with news and information and software to download The basic Prestel service is available to home users for 5 per quarter at present There are other databases costing stil
251. er ent is that the signal on the data input pin is routed through the multiplexer to the cell During a conventional write cycle the data output pin will follow the output of the cell while CAS is active This might seem to preclude the use of dynamic memory in cir cuits usually associated with static memory where the same lineis used for data input and out put but it is possible to prevent the output of a dynamic memory from coming on when goes active by arranging for the te signal to go active before does These early write cycles are common in large systems but are not found in most eight bit microprocessors such as the Z80 where the WR signal goes active well into the memory cycle and is too late to be of use One answer is to use an eight bit three state buffer between the ram outputs and the data bus but my solution is to use the inverse of as a write strobe to the memory Whenever RD goes high i e at the end of reading memory or i o the write strobe goes low and sothe dynamic memory is primed for an early write As will be over long before RD goes high there is no chance of a memory read cycle being transformed into a memory write cycle Should it be a read cycle then the write strobe is removed from the mem ory by RD going active low at the beginning of the cycle well before CAS is applied Except for a slight increase in current consumption during the write line strobe the effect is unnoticable
252. er cont Additional relays 1 65 Sic Add 65p postage amp packing 15 VAT to total mmm Overseas Customers COMPUTER SHOWROOM Add 2 50 Europe 6 00 elsewhere for p amp pi Send S A E for further STOCK DETAILS TOP HARDWARE LATEST SOFTWARE Goods by return subject to availability PERIPHERALS ACCESSORIES AND OPEN 9am to 5pm Mon to Fri MUCH MUCH MORE 10am to 4pm Sat FAST TATE TOP QUALITY LOW LOW PRICES No circuit is Complete without a call to ELECTRONICS 11 13 Boston Road m HEU 2510 ORDERS o London W7 3SJ 01 579 2842 TECHNICAL after 3PM CIRCLE 039 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW SOUTH MIDLANDS COMMUNICATIONS A M COMPONENTS LTD EXC SS SS L of TEST y eR CE Aa VALVE amp COMPONENTS SPECIALISTS E EQUIPMENT 3 et RCUITS sro 795 teasdo 1 25 TDA2523 1 95 YC1000L INTEGRATED CIR UITS STK415 7 95 T8A540Q 1 35 TDA2524 1 95 DATA PROCESSOR ANT24 250 MOSS 1 50 SIS 7 95 ae 14 TDA2530 1 95 AN214Q 2 50 C1352P 1 25 K4 7 95 TDA2532 1 95 SERVE EDD AN240P 2 80 MC1357 2 35 STK439 7 95 TBAS60CQ 145 TDA2540 1 25 AN612 2 15 MC1358 1 58 TA7061AP 3 95 TBA570 1 00 TDA2541 2 15 PULSES AN7140 3 50 MC1495 3 00 TA7108P 100 TBAG41A12 TDA2560 2 15 TEMPERATURE AN7145 3 50 MC1496 12
253. eration is simply a matter of sending a division ratio and control word to the 8253 timer counter i c 30 ZX81 INTERFACE forms are constructed form a number of discrete segments A drawback of this method is the time taken to build the shape i e if 128 steps are used a clock running at 128 times the resulting waveform frequency is required The more steps the better the waveform but for most applic ations 128 steps suffice Digital values representing segments of the waveform are supplied to the d to a converter by the computer in the appropriate sequence These values may be calculated by the computer and stored ready for transfer List 2 used to gener ate sinewaves is easily modified to produce more segments or other waveforms Squarewaves can be generated in many ways the simplest being to use a continuously looping pro gram which sends one and zero logic levels alternateley to the output Fig 2 Using Basic and ZX81 fast mode the highest fre quency obtained is 190Hz or 12kHz using machine code lower frequencies are obtained by intro ducing a delay into the program Different delays between the two logic levels will produce pulses but more interestingly the delay may be varied each time round the loop to produce swept fre quencies or frequency modulated signals Drawbacks to this approach are that matching the delay to the EUER required is done by trial and error and the upper
254. erface Addition of a few i cs to the ZX81 allows one to measure and generate signals with remarkable ease and accuracy This simple circuit provides a signal generator a d v m a frequency counter timer and a spring boa to microprocessor interfacing Apart from its applications in games and bank balance analy sis the home computer can prove auseful tool for measurement and control This simple interface provides a signal generator d v m and frequency counter timer and although it has limit ations in relation to professional instruments its performance is more than adequate for many applications Basic program examples shown are tried and tested but you will no doubt find ways of improving them Higher operating speeds can of course be obtained using machine code Although Lares and sof ware were designed for the ZX81 modification to suit other micro computers should be easy Digital voltmeter Conversion of analogue levels to digital form may be carried out using a digital to analogue con verter d to a and comparator circuit The program is designed so that the computer sends out digital information to form an analogue ramp at the converter output Fig 1 The comparator compares the signal to be mea sured and the ramp voltage when the two are equal the comparator output connected to the computer input changes state On detecting this change of state the computer halts ramp generation and so holds the d
255. ericanradiohistorv com TOROIDALS STEEL DISHED WASHER AB OUTER INSULATION The toroidal transformer is now accepted as the standard in industry overtaking the obsolete laminated type Industry has been quick to recognise the advantages toroidals offer in size weight lower radiated SECONDARY z NEOPRENE fi LJP PRICE WASHERS ield and thanks to I L P WINDING Our large standard range is complemented by our SPECIAL DESIGN INSULATION section which can offer a prototype service within 14 DAYS together with a short lead time on quantity orders which can be programmed PRIMARY to your requirements with no price penalty WINDING anie END CAPS T 15VA 50 VA 126 VA 225 VA 500 VA 62 x 34mm 0 35Kg 80 x 35mm 0 9Kg 90 x 40mm 1 2Kg 140 x 45mm 2 2Kg 140 x 60mm 4Kg id Regulation 1996 Regulation 13 Regulauon 11 Regulation 7 Regulation 4 Why a Toroid x 5 SERIES SECONDARY RMS 2 010 6 6 416 43010 6 6 1000 6x012 12412 938 81016 25 25 10 00 Smaller size amp weight to meet No Volts Current 23011 9 9 277 4x011 9 9 6 66 0 22 5 20 8x017 30 30 833 modern slimline requirements 2x012 12412 208 4x012 12 12 5 00 x014 aBe 25 8x018 35 35 714 i i 0x010 6 6 125 21013 152415 166 Big STIS REA 6x015 511 Bio2o3 40240 ds _Low electrically induced 0x011 9 9 083 23014 38418 138 43014 18518 333 62016 450 83025 45 445 555 noise demanded by compact 0x012 12412 063 2x015 22 22 133
256. ernal video reference such that off tape video has the same timing as the reference which means that correctly timed play back can take place at one tape speed only Furthermore the video head will only accurately trace the tape tracks if drum and capstan turn in a fixed relation Sup or variable speed playback WIRELESS WORLD MAY 1984 the capstan servo must be unlocked thus the video head will no longer accurately trace the tape tracks and the timing of the off tape signal will no longer correspond to the reference Two systems are necessary to overcome these problems track following video head solves the geometrical problems and a timebase corrector restores the timing to that of reference video Horizontal Video alignment offset Video track following Track following was originally applied to video recording in order to improve compatibility between machines This tech nique will be discussed first fol lowed by the additional require ments of variable speed track fol lowing The principle appears under various trade names Audiol by J R Watkinson M Sc B Sc Fig 1 a shows essentials of PAL C format Tape is guided round drum at helix angle but movement of tape agains drum rotation causes track angle to be slightly smaller than helix angle Tape speed is chosen to give video offset of 3 5 lines which gives horizontal alignment condition inset Vertical interval storage is optio
257. es with the IEC 625 1 standard and can be Noof Header Recep Edge 12 pio 16 pino pin Spin connected to up to 14 other devices Interface ways Plug tacle Conn ene ae 2n x aoe Solder IDC Grey meter board is supplied complete with software in ROM i 930p 85p 720p MAPS id F eG wayiplugientronics 10 way 40p interconnecting cables IEEE cable for connection 70 pp mp Jp 24 Ribbon Cable with Sockets 5 25 5 25 16 way 60p 5 26 175p 150p 240p lt 36 way socket Centronics CUIU to an external device and a comprehensive manual 54 200p 160p 320p 20 pin 26 pin 34 pin 40 pin 550 5 50 20 way 85p E2825 Ori EeioOICarT 40 220p 190p 340p lend 160p 200p 280p 300p j i i ZBQNAY ei ind 50 235p 200p 390p 2ends 290p 370p 480p 525p 2A WayplugIEEE 5 90 SERE RES 190p E i 24 way socket IEEE 5 00 4 75 40 way 180p aR yr ym 50 way 200p D CONNECTOR Ribbon Cable with D Conn POCO EE eee SU 64 wav 280p SMARTMOUTH ACTORS sweeser o Femuiestop 2way 86 00 Sway 25 37 m TET aae SPEECH SYNTHESISER FOR BBC MALE RS 232 JUMPERS EURO EDGE T Sok 80 105 160p 250 The infinite vocabulary self contained M Anja 150p 210p 250p 365p sway D CONNECTORS CONNECTORS speech synthesiser unit Uses only 5 10 FEMALE 24 Single end Male soo D N41617 Pug Sk 01 0 156 1 bytes per word no ROMs required Solder 105p 160p 200p 335p 24 Single end Female tho MAY 1705 doo 2x8 way Commodore 300p simply plugs into the user port Has Aux
258. essional guidance Call 076 384 676 till Bpm most evenings or send your C V no stamp needed to ELECTRONIC COMPUTER AND MANAGEMENT SERVICES LIMITED Freepost Barkway Royston Herts SG8 8BR RESEARCH INSTITUTE University of Petroleum and Minerals DHAHRAN SAUDI ARABIA BRIGHTON POLYTECHNIC LEARNING RESOURCES Senior Audio Visual Technician 6 264 7 896 To be responsible for the organisation and operation of the audio visual equipment loans service which supports teaching at the Mouslecoomb site of the Polytechnic Equipment includes production standard colour video cameras 3 4 and 1 2 video recorders and multi standard video replay production quality sound equipment including Revox and Uher recorders along with film and slide projectors Candidates must have experience of the operation and maintenance of equipment of this kind and be able to E with a wide range of acedemic media production and engineering staff candidates must also have good organisational skills City and Guilds Final Certificate or TEC qualifications in a relevant area of electronics an advantage Needs Digital Electronics Repair Technicians for expansion of the facility for instrument repair maintenance and calibration Candidates background should include Bachelors or associate degree or equivalent military Technical training Minimum 4 years hands on digital experi ence on micro mini computer
259. ester Bath Luton Stoke on Trent and Worthing The Leicester GB3GV channel RMT1 Luton GB3TV Channel RMT2 and Worthing GB3VR channel RMT2 repeaters should be active by the time these notes appear Aerial polarization both incoming and out going is horizontal RMT 1 has vision in 1276 5 MHz vision out 1311 5 MHz sound in 1282 5 MHz and sound out a m 1317 5 MHz RMT has vision in 1249 0 MHz vision out 1318 5 MHz sound in 1255 0 MHz sound out 1324 5 MHz The British Amateur TV WWW americanradiohistorv com Club has appealed to its members Since these are the first such licences to be issued in the UK it is incumbent on us all to usethe facilities in a responsible manner in order that the authorities may look favourably on any future expansion plans to the amateur television network In brief Dr Owen Garriott W5LFL the radio amateur scientist on board the STS 9 Space Shuttle took part ina London meeting of the Royal Society during February where the general scientific work of the mission was discussed There are signs that future Space Shuttles are likely to have amateur radio equipment on board but most observers agree that it will be essential to achieve greater operational discipline and co operation by those on the ground as well as a less noisy environment on board the Shuttle Japan is introducing 900 MHz c b with 80 channels and 25 kHz spacing Automatic transmission of identification
260. ex Bell 103 originate loopback Bell 103 answer loopback Bell 202 main loopback Bell 202 with equalizer loopback CCITT V 21 originate loopback CCITT V 21 answer loopback CCITT V 23 mode 2 main loopback CCITT V 23 mode 2 with equalizer loopback CCITT V 23 mode 1 main loopback CCITT V 23 back loopback Fig 3 Connection to the telephone line can be via an acoustic coupler or below through an op amp duplexer and an isolating transformer 61 CONG fS lz T 624 ANG d REST Fo POOLE NEG ay MEN Aire Seinen 4E The information society 1 Technology politics and infrastructures A E Cawkell looks back at his 1978 piece The paperless revolution and forwards to the year 2000 In this first article he considers the interactions of politics with technology and the infrastructures which influence support and enable an information society 62 WIRELESS WORLD MAY 1984 WWW americanradiohistorv com In 1978 I wrote an article in this journal about forces controlling the introduction of new technol ogy At that time the arrival of the silicon chip just introduced to a marvelling public was being discussed with both optimism and foreboding The article was entitled The paperless revolution and fea tured a machine called the Con sumersole an information inter face between man and the world outside to become a reality per haps by the year 2000 universal data communicatio
261. f an aether theory in terms of which all motion must be speci fied absolutely That theory was of course the Maxwell Lorentz electromagnetic theory also known as Maxwell s Equations It is best to be frank and not mealy mouthed about these his torical facts By the year 1905 electromagnetic theory had already failed on three separate experimental counts namely 1 The physical aether upon which it depended for its operations does not exist Michelson and Morley 1887 2 The radiation of energy in the form of light is not a continuous process Planck 1899 3 Light quanta photons do not dissipate whilst in transit in vacuo Einstein himself 1905 In addition it had become clear by the tum of the century largely as the result of the brilliant work of H A Lorentz that the theory had also failed internally in that it could not handle even the sim plest of situations involving rela tive motion Einstein was acutely aware of this problem In his view some thing was obviously wrong In the preamble to his Special elativ i o On the electrodynamics of Moving Bodies he took it as one of his starting points He wrote 1905 Customary electrodynamics does not take into account the experimentally corroborated lack of absolute motion The descrip tion of amagnet moving relative to a conductor at rest is quite differ ent from the description of a con ductor moving relative to a magne
262. facturers Association US has along list of popular WIRELESS WORLD MAY 1984 FEEDBACK values few of which are our preferred number Colour coding yes E6 or E12 no One important trick and a jolly good one was to link value and colour The use of 3 3 instead of 3 2 means more colour contrast and as it means 2 7 to 3 9 anyway how does it matter To use the full colour range we can pick either 4 7 6 8 or 4 6 6 7 But 4 7 6 8 gives usa double colour contrast The committee in fact lifted its collective eyes from the slide rule and looked at the real world as they knew it Full acceptance of the system came only with the War with the drafting of specifications and lists and with pressures on designers like the ruling that even 10 tolerance could only be used if application and justification were made in writing The functional nature of the preferred number series was discussed in a series of articles in Wireless Engineer nearly 40 years ago The initial problem was to produce simple band separating filters the sort the PO used to provide if a local embassy transmitting in the h f band interfered with your Band I television subject to the condition that the capacitor should have preferred values The usual method was to design conventionally and wonder what the effect of 220 instead of 270 would be Using as an example the typical equation C 1 2Tf R we have log C log 2r log f log R
263. ference Service teams will fit suitable filters in fibreglass units near the homes of radio amateurs but only if complaints are received Since the BT cable installation at Milton Keynes is normally regarded as a technically advanced system the problems that seem likely to arise as more and more television signals are distributed at frequencies within the amateur bands may prove severe 90 000 plus At the end of December 1983 the number of UK amateur radio licences was 50 635 of which 24 359 were Class A and 26 276 were Class B During 1983 the number of Class A licences were thus for the first time overtaken by the no morse test Class B licences 144 MHz and above Whenthe Class B licence was introduced in June 1964 it was for 420 MHz and above only and was then intended to encourage the development of the U H F bands by technically minded experimenters Unlike the FCC system where radio amateurs voted 20 to 1 against the introduction of a no code licence the British Class B licence for first u h f and later extended to v h f resulted from closed door discussions The FCC state Morse code is a fundamental communications skill critical to the nature of the Amateur Radio service ATV repeaters The DTI have approved the setting up of the first five amateur television repeater stations in the UK They will use the 1 3 GHz band and acepting vision and sound a m or f m signals located at Leic
264. fibre axis as illustrated in Fig 2 Silica is used for the majority of fibres with either ger manium or boron doping to achieve the desired refractive indices Inexpensive fibres can be made from perspex polymer but they exhibit very high losses of around 500 1000 dB kin The most convenient type of fibre to describe is the multimode step index fibre of Fig 2 a where the core region has a constant refractive index n that is larger than the constant refractive index n of the cladding region This fractional refractive index step difference A is only small usually around 1 but is sufficient to produce light guidance by total internal reflection under certain conditions In a multimode fibre the core diameter is large compared to the wavelength of light hence propagation in the fibre can be modelled adequately by using geometrical optics Fora typical multimode step index fibre we might have n 1 5 n 0 99n with A 0 01 core diameter of 50um and a cladding diameter of Tobin Lengths of optical fibre can be joined together with ey low osses 0 1 to 0 3dB by fusing their ends together whilst clamped in a special alignment jig Demountable connectors require a high degree of mechanical precision for best results with losses of around ldB per connector pair being WIRELESS WORLD MAY 1984 typical In Figure 3 a point source is shown emitting light rays over a wide range of angles Ray lenters parallel to the fi
265. ficiency The synchronization electronics can automatically lock onto an output operating frequency so that it will synchronize with the output of for example an IBM3279 terminal even though this uses a non standard vertical frequency the ECP1000 can scan and hold frequencies between 15 and 33kHz horizontally and 45 to 100Hz vertically This permits the projector to be used with many different output devices from personal computers to high resolution graphics terminals With an optional adaptor and a tuner the system can be used to display broadcast tv or v c r images which benefit from the high resolution of the system Electrohome Ltd 7 Civic Way Ellesmere Port Cheshire L65 0AX WW 213 L MADE EDDEEDILOLLLILCCRLE GILRECOCOLQOLLBCILLGLI CLLLL GCGXAL FLOPPY TAPES We have received news of two very similar products which are both intended to improve the reliability and speed of tape storage for microcomputers for those who cannot afford disc drives The Ultra drive from Ikon uses a standard cassette offering aread write speed of 1200 characters s and a capacity of around 200k bytes on each cassette version compatible with the Dragon 32 computer is now available 79 95 and others for the BBC Nascom Tandy Oric Electron and Commodore computer are to be available soon Ikon computer products Kiln Lane Laugharne Dyfed WW 214 different approach is taken by Phi Mag Systems who have
266. for inaccessible heads 4 85 es cw COMPONENTS We now list a wide range of individual components many ef which are not availabie elsewhere Send for your copy of our latest list which also gives further information on our Kits Latest MPU controlled 80 Track Drives support single or Please add part cost of post packing and insurance as follows doubie density Fully compatible with Teac Shugart and nan other ful and half height drives 80 Track Single side 179 80 Track Double side 225 Full manual for each type 14 50 No VAT INLAND Orders up to 10 50p Orders 10 to 49 1 Orders over 50 1 50 ALL PRICES EXCLUDE VAT UNLESS STATED 4 qu J 0691 652894 ur OVERSEAS Please send sufficient to cover Surface or Air Post as required Front loading deck with full solenoid contro of all functions including optional read in fast wind modes 12 volt operation Fitted 3 digit memory counter and Hall IC Motion Sensor Stan dard erase and stereo R P Heads Cheapest price ever for all these features On y 38 90 plus VAT Full technical specification included Personal callers are always very welcome but please note that we WC are closed all day Saturday NN d VN md WIRELESS WORLD MAY 1984 85 WWW americanradiohistorv com x 01 452 1500 TkcuNoMaric Lro 01 450 6597 BBC Micro Computer System OFFICIAL DEALER BBC Modei B 348 FLOPPY DISC INTERFACE 84 amp 15 installation B
267. frequency is rather limited more elegant way of controlling the generation process is to use a dedicated cir cuit such as the 8253 which has three separate and independently programmable 16 bit counters The device operates by dividing a clock signal by a certain prepro grammed value and functions up to 2MHz Each counter may be used in one of five modes includ ing ones for pulse and squarewave generation Unfortunately when the divisor is samll gaps between each programmable frequency are large i e f 2 f 3 f 4 etc but with a high clock frequency this is not so important List 3 is a program for square wave generation and simply requires a control word and two data bytes for each counter sec tion Division factor n is the clock frequency divided by the output frequency and must be equal to or greater than two It is presented to the circuit as two bytes The computer may be used to calcu alte these bytes using Most significant byte Output zero Delay t1 Output one t2 FREQUENCY MEASUREMENT WWW americanradiohistorv com X see fig 4 PERIOD MEASUREMENT integer z Least significant byte z integer 555 X 256 Where n is low the resulting fre quency s precise value can be cal culated by dividing the clock fre quency by the integer of n How to use the 8253 timer is outlined separately Frequency period measurement Frequency is measured by simply counting the num
268. gulators LM358N 028 Pin Tin Gold W W 2114L 20 DI 092 78L05 026 f 4116 15 D2 105 78L12 026 LM383N 934 8 010 024 058 4116 20 D2 088 78L15 0 26 LM725CN 133 14 012 028 077 4118 15 DI 375 7805 pas EMPICE 018 16 013 032 086 4164 15 D2 433 7812 033 IMITER 048 18 O16 032 108 4164 20 D2 395 7815 033 LM748CP 022 2 017 04 123 4416 20 D2 660 7905 046 MC1413P Dl O86 22 017 048 131 4564 15 525 7912 046 MCIAIG Di 066 24 020 063 144 5516 25 773 7815 046 MC1458CPL 026 28 023 057 159 6116 3 D1 372 LM309K ogg MCIASSL 713 40 033 099 196 MC1496P 065 61 16 LP3 D2 467 LM317K 1 2 MS eae 2 2532 45 D2 350 LM323K 4 2708 45 D2 325 LM338K 521 MC3242A i5 EHE Suchet x MC3302P 040 in 2716 35 DI 450 78HGASC 813 23 P 835 MC3340P 197 in 2716 45 DI 350 78H05SC 628 Aan 96 40 Pin 845 2716 3 Dl 450 78HI2ASC 740 Men P ae 2732 35 DI 458 78S40DM 628 MCMAAIL vun 2732 45 DI 375 78540PC 250 MC3MIAP 40 Datasheets are 2764 30 Dl 392 M Mn Di a available on items PEL 2EONS BBC 395 8800 Family MCOMBAP DI 332 Prices are as follows 2564 30 D2 600 6800 D7 287 MC3470P El repos i esed 27128 30 D2 24 50 8802 DS 261 MC3480P DS 647 6803C 583 MCM8P DI 150 D2 100 D 300 Buffers 6809 pe 713 MCIAMII Di 852 D3 125 D7 4 00 8ILS9S gas 6810 D 125 MCI4412 1187 D4 200 8ILS96 oas 6821 D3 131 NESSSP 019 81LS97 gas 8840 D4 392 NESS6CP 045 Alullrange of the 81LS98 095 6843L 2088 RO32513L DI 782
269. he area also offers reasonably priced housing Relocation assistance may be available For further information and your application form please telephone Cheltenham 0242 32912 3 or write to Recruitment Office Government Communications Headquarters Oakley Priors Road Cheltenham Gloucestershire GL52 5AJ 2452 ARTICLES FOR SALE Cameron Communications an expanding division of C W Cameron Ltd is a well established leader in the Visual Communications market with high quality products for the professional and industrial users including Colour Graphic Displays Interactive Video Systems Video Projection Videotex Terminals Broadcast and Industrial Video Equipment Touch Screen Displays Computer Graphics Projectors The continuing growth and success of the company has resulted in the creation of further career opportunities based in our new Reading Office SENIOR ENGINEER Video Computer Products Ret REO Salary Negotiable Based Reading Plus Car A Senior Engineer is required to head a team of engineers operating in a modern well equipped department providing technical assistance to the Sales Group OEM Customers Dealer Network and End Users Key activities will include the organisation of documentation system to cope with the expanding product line and installed equipment base Provide and maintain a technical intertace with the company s suppliers and its customers and introduce equipment
270. heque Vocal Public Address Speaker outlets for 4 8 or AUTOCHANGERS 240 VOLT GOODMANS HPD DISCO 12in 120 8 15 29 50 2 36 ohms Four inputs 20 mv 50K ohm Individual volume controls BSR Budget Rum Ceramic 18 GOODMANS HP BASS 15in 250 8 72 4 Four channel mixing Slave output 16 x8 x5 2 Wt BSR Deluxe Rim Ceramic 20 GOODMANS HPD BASS 1Bin 230 8 84 4 14lb Master volume control 240V A C Post 2 BSR Deluxe Rim Magnetic 25 100 Vott Line Model 150 watt 114 MONO SLAVE 150 watt 80 GARRARD 6200 Rim Ceramic 22 nae clara aati Qu Ta win Inputs for 3 50 Baker Stereo Slave 150 150 watt 300 watt Mono 125 Post 4 m ls 1 I volu ntr THE INSTANT BULK TAPE ERASER 11 50 Post 95p and PC Board Can be ganged for multi channel Post B5p BAKER MOBILE PA AMPLIFIER Ali transistor 60 watt RMS 12v Suitable for cassettes and all sizes of tape reels AC mains ae DC amp 240v AC 4 inputs 50k Aux 2 mics 200 250V Hand held size with switch and lead 120 volt to order MAINS TRANSFORMERS Post phono Output 4 8 16 ohm 100 volt line 89 Post 2 Will also demagnetise small tools Tape Head Demagnetiser 5 PEINE POMA BAV TA M 1A Ex z WATERPROOF HORNS 8 ohms 25 watt 20 30 watt 23 40 watt ALUMINIUM CHASSIS 2 2 n deep 6x4 1 75 8x6 2 20 10x7 220V 25ma V lamp 3 00 220V 45ma 6V 2 Amp 4 00 1 26 40W plus 100 volt line 32 Post 2 2 15 12x8 3 20 14x9 3 60 16x6 3 16x 10 3 8
271. hich we already know by exper iment to be wrong we are asked to accept the Lorentz transfor mations which contravene all our existing experience of the nature of time and space on the basis that the velocity of light is the same relative to all material things whatever may be their motions relative to each other which certainly seems to deny ordinary logic Perhaps there may be a higher logic The whole thing begins to look like a confid ence trick One is always adjured to accept this theory simply on the grounds of the success of its predictions but would it not be more convincing to get a line on the truth or otherwise of Ein stein s second postulate from Ein stein himself if only one could find a way Signal error at the trackside Einstein acknowledged that some physicists as opposed to mathematicians might have diffi culty in swallowing these wayout ideas so he developed an inter esting argument about the nature oftimeand simultaniety He envi saged a section of straight railway track running along an embank ment from to B with M as its measure mid point see Figure 1 During a thunderstorm light ning strikes the rails at both and B simultaneously But what does one mean by simultane ously he asks and replies sim plistically If the observer at M perceives the two flashes of lightning at the same time then they are simul taneous This is Einsteins definition of
272. hostilities He never discussed this work even years later He liked to tell the story of coming back to Dorset House the home of Wireless World years later to be greeted by the newspaper seller at the door with Evening Standard as usual sir The equally undramatic Cocking simply said thank you In the post war era with the editor H S Pocock and later F L Devereux Walter Cocking made an enormous contribution to Wireless World helping to maintain and improve the engineering standards and integrity of the journal Pursuing his goal of excellence in engineering he developed an audio amplifier using triode valves in push pull PX4s that preceded the famous Williamson amplifier Whilst continuing to provide constructional articles and other more theoretical material he edited the famous Wireless Engineer Under his editorship this achieved such a reputation for quality and integrity that a number of overseas universities accepted publication of a paper or thesis in it as being of appropriate standard to award the author a degree Later in his career Cocking became editor in chief of Wireless World and of the successor to Wireless Engineer He retired in 1972 but maintained constant contact through letters to the editor A truly great technical journalist Walter Cocking was a tremendous influence on all who worked with him and will be sadly missed TJB WIRELESS WORLD MAY 1984 An ICOM remot control rec
273. husiasts amp Professionals require a reliable source of quality amplification crimson continue to meet this demand with a comprehensive range to suit virtually every application and support this with friendly advice and back up Our prices have remained stable for 18 months and with two regional distributors and our own mail order system there has never been a better time to choose the best pst ae a e ew oe Power amplifiers bipolar type Incorporating full electronic protection Still the reference kit amplifier for less than 250 you can own an esoteric integral heatsink bracket high stew low distortion circuitry lt 0 01 THD TYPICAL pre power combination with the added pleasure of building it yourself Write for our full brochure and review reprints TYRE MAXO R SUPPLY DC PRICE CK1010 Stereo pre amplifier 92 00 CE608 60W 8R 35V 21 50 CK1040 Stereo P A 40 40 WPC 121 00 CE1004 100W 4R 35V 25 00 CK1080 Stereo P A 80 80 WPC 134 00 CE1008 120W 8R 45V 28 00 CK1100 Stereo P A 100 100 WPC 151 00 CE1704 200W 4R 45V 35 50 MC2K M C kit for CK1010 25 00 CE1708 180W 8R 60V 35 50 P S K Pre amp power supply 20 00 CE3004 320W 4R 60V 49 50 DUPESUET PRO POWER A new range of 19 rack mounting power amplifiers are undergoing field CE308 30W 8R 25V 15 90 trials for launch later this year Please contact us if you have a particular Power amplifiers Mosfet type Ideal for hea
274. i 40 Was e7 CPP ELS can Offer excellent prospects BONN i in the above disciplines AUDAX eee Services London Ltd 8 25 watts 2185 n watts 5 50 PP ion Aj h amp Northwood HAG 2XN TRADE ENQUIRIES VERY WELCOME Audax 30 watt mid 3 80 3 10w 42 2 50 10 watt St Aisne 0727 30802 2534 tweeter 1 60 Elac 7 3 3 4 1 60 Shadow 6X4 4Q 1 85 6 2 I T T 6 K4 4Q 10 watts 5 d Peerless 5 md 1 75 Eagle 2 1 4 tweeter 95p 40ohm tweeter 65p Audax 2 way 30 watt Crossover 70p All tems 65p PP STD 0927421622 Agy Celestion 15 50 watt 15Q 20 10 x6 1 2 5 50 GRADUATE DESIGNERS wanted to join video i tex specialist firm based at Whitechapel Technol STUART SPARES ogy centre Must be versatile experienced and HIGH ST SOUTH RUSHDEN NORTHANTS familiar with the viewdata system Call John Bar 9935 31233 2 CLOSED MONITUES 2553 ton on 01 377 1982 2561 ARTICLES FOR SALE BBC MICROCOMPUTER GENLOCK ROAD This card type 630B enables the RGB and monochrome video outputs of the computer to be locked to an external Apr stal NS s t RELIABLE P Ae Private enquiries send 3p in stamps for brochure THE QUARTZ CRYSTAL CO LTD Q C C WORKS WELLINGTON CRESCENT NEW MALDEN SURREY 01 942 0334 amp 2988 i video or sync signal The card is supplied complete ready to fit inside the computer with full installation instructions For
275. ic Market driven service infrastructure Unemployment Information eee technology industry Hardware lo o M A software s ate information market E E Business professional amp domestic users oes Old technology The government has a role in co ordinating national and inter national standards Perhaps it can best continue to do that by supporting organisations like NPL British Standards and ISO in the UK National Bureau of Standards and ISO in the US and similar activities in other coun tries In the US the IEEE has suc ceeded in establishing standards which have become international such as the RS232 communic ations interface Some manufac turers have established de facto standards such as Digital s CP M microcomputer operating system software and IBM s SNA commu nication protocol Europe often follows the US in this field In Europe German DIN standards have been adopted in some fields not in information technology Telecommunications and the market A service infrastructure will be the technological backbone of an information society Digitized information or for the purists data which may be one man s information but anothers noise will flow from source to recipient WWW americanradiohistorv com ti Fig 1 The information infrastructure and the forces which influence it 65 66 Si RR a RS a aaa a aad THE INFORMATION SOCIETY I a
276. ice 15 2 p amp p total inci VAT 1955 Foolscap SAE for further details inciuding Hy Lyght and Industrial Strobe Kits ULTRA VIOLET BLACK LIGHT FLUORESCENT TUBES Aft 40 watt 8 70 VAT Callers only 2h 20 watt 6 20 125 p amp p 857 inc VAT 18n 15 watt 350 75p p amp p 488 inc VAT 10 watt 3 25 75p p amp p 460 inc VAT 12n 8 watt 3 00 45p p amp p 397 inc VAT 9i 6 watt 250 45p p amp p 339 inc VAT 6m 4 watt 2 50 45p p amp p 339 inc VAT 230V AC Balisst Kit for either amp in Sin or 12in tubes 5 50 p amp p 55p 6 96 inc VAT For 13in amp 18in Tubes 6 p amp p 75p E7 76 inc VAT For 12V DC op 12in amp 13in tubes oniy 5 50 p amp p 75p 7 18 inc VATI 175 WATT SELF BALLASTED MERCURY BULBS Available tor ether BC of ES fitting price 11 79 inc p amp p and VAT 400W UV LAMP AND BALLAST complete 38 post 3 50 47 73 inc VAT amp p amp p 400W UV LAMP only 14 post f2 18 40 inc VAT amp p amp p L T TRANSFORMERS Special Offer 0 6 3 V 0 6 3 V at 10 Amp 12V 0 10 Amp or 6V at 20 Amp Price 9 00 p amp p 2 00 inclusive of VAT 11 50 N M S 12 24V D C Reversible Precision built motor maufactured by Escap will operate from 24 V down to 2 V DC Current consumption negligible A range of speeds between 2 to 36 RPM obtainable 6 Voit DC 8 r p m N L 6 MA 12 Volt DC 18 r p m N L 10 MA 24 Volt DC 36 r p m N L 18 MA Total length of mot
277. icting factor on the operational bandwidth length product it is d well eyond 100GHz km Instead the practical restriction placed on the bandwidth length is due to the second mechanism that of fibre material wavelength disper sion and the spectral width of the optical source Material dispersion Material dispersion refers to the variation in group velocity with wavelength of light in the fibre The dispersion causes pulse spreading in fibres driven by opti cal sources with a finite spectral width the greater the source spectral width the greater the pulse spreading and therefore the lower the bandwidth length pro duct A typical 0 85um l e d exhibits a spectral width of around 0 05um 50nm in con trast to an injection laser diode whose spectral width is Dno 0 002um 2nm These figures translate to bandwidth length products of about 500MHz km and 25GHz km for l e ds and WWW americanradiohistorv com Visible red light rather than infra red is often used with the low cost polymer fibre shown 43 After a postdoctoral fellowship at Manchester University Brett Wilson taught in Baghdad for a year and then returned to work on optical position detectors and sensitive non contact current measurement He then lectured at Nottingham University where he s been concerned with novel uses of op amps in addition to fibre optics and from Easter returns to Manchester this time at UMIST His Ph D was on a high
278. ificing quality Heres what Personal Computer News had to say about our monitors There is no doubt that the JVC range of ECM colour monitors is excellent value for money there is no loss in quality of picture after long periods remember as more and more resolution is available with new micros the need for a better display will be that much greater For those who only require medium resolution we also have a model 370 x 470 pixels at 179 95 excluding VAT which is equally excellent value for money Both units have a 14 screen and are suitable for the BBC Micro Spectrum QL Lynx Oric Apple IBM and MODEL REFERENCE 1302 2 High Resolution 1502 1 Meum Resolution RESOLUTION SHO x 70 Pixels STUN TO Pixels Colo M Ea SUPPEX 220 2408 50 OOH 220 2408 50 00147 EHT Minimum 19 Sky Minimum 19 Shy Maximum 22 Shs Maximum 22 Sky VIDEO BAND Y IDTH 1OMPBHZ OMIT t characters by haracters by DISPLAY 80 characters by HO characters hy 25 lines 25 lines SLOT PITCH O4imm 065mm t Wr SITIS RGB Analogue RGB Analogue gt BRU Ee TTE Input VIL inpu ay Separate Sync on R G B Separate syne on R O B SYNC h E SS Positive or Negative Positive of Negauve TENER PRES On ott switch and On off switch and EXTERNAL CONTROLS brightness control brightness control EX VAT most other leading micros And naturally theres a years full guarantee Another one of our commi
279. ig Gen TESDA 5 1 Sig Gen TF2120 Waveform Gen Tektronix 284 70pS Pulse Generator TEKTRONIX PLUGINS We stock a complete range of Plug Ins for use with 7000 and 5000 series Mainframes TEKTRONIX TM500 SERIES We stock a very wide range of these versatile modular equipments MISCELLANEOUS Avo Model 8 Multimeters 7 Electricians Multimeter Bruel amp Kiaer 2209 Sound Level Meter 1613 Filter Bryans Southern 25000 XY T Recorder 750 00 26001 A4 with 2 x 26116 Amplifiers and 26201 Timebase 1 400 00 As above but with 26202 Power Unit instead of Timebase 1 250 00 29300 XY T Recorder 1 000 00 Gen 10KHz Synchroniser 3 000 00 1 350 00 1 350 00 850 00 950 00 80 00 65 00 aay 00 400 00 Superb Condition Price 850 Datalabs DL901 Transient Recorder Fluke 8010A 01 A digit DMM with built in batterypack 150 00 8050A 412 Digit DMM 200 00 9318 Diff V Meter 1 000 00 2020A 3 6 Printer 500 00 8921A DMM 695 00 750 00 Hewlett Packard 427A AC DC Voltmeter 95 00 461A Amp 20 40DB 1KHz 1 SOM 467A Amplifier 725 00 415E VSWR Meter 950 00 3556A Psophometer 850 00 3552A Trans Test Set 1 500 00 4815A Vector Impedance Meter 3 850 00 Marconi 2438 520MHz Counter Timer TF1313A LCR Bridge TF2603 RF Millivoltmeter Racal 9514 Counter Timer IEEE 850 00 9804 50MHz Counter Timer 325 00 Tektronix 106 Square Wave Generator 1nS risetime 10Hz 1MHz wi
280. ight damage the tele phone network as well as being dangerous for its users Constructional details of a modem using the Am7910 will follow next month WIRELESS WORLD MAY 1984 MULTI STANDARD MODEM Table1 Frequency assignments In the Bell 202 back mode a 387Hz tone corresponds to a mark its absence to a space Bell 103 originate Bell 103 answer CCITT V 21 originate CCITT V 21 answer CCITT V 23 mode 1 CCITT V 23 mode 2 Bell 202 CCITT V 23 back Bell 202 back Data rate baud Duplex Transmit Receive frequency frequency space mark space mark Hz Hz Hz Hz 1270 2225 2225 1270 980 1650 1650 980 1300 1300 1300 1300 1200 1200 390 390 Table 2 Control pins on the Am7910 provide selection of nine operating modes and ten loopback modes for testing Optional equalisation is available to cope with long or poor quality lines oooo ooooo A E cR E oo oocooo 0 000 ooooo a RC ATO WWW americanradiohistorv com oooo a O00 OO oo oo 0 9C0 0 ooo oo 0 0 ooo 0 0 0 0 0 Bell 103 originate 300 baud full duplex Bell 103 answer 300 baud full duplex Bell 202 1200 baud half duplex Bell 202 with equalizer 1200 baud half duplex CCITT V 21 originate 300 baud full duplex CCITT V 21 answer 300 baud full duplex CCITT V 23 mode 2 1200 baud half duplex CCITT V 23 mode 2 with equalizer 1200 baud half duplex CCITT V 23 mode 1 600 baud half dupl
281. igital equivalent of the unkown analogue signal Pro gram flow for analogue to digital conversion program is also shown in Fig 1 This cycle may be repeated continuously as it does in the digital voltmeter program List 1 Using a technique known as successive poroa would be faster but I haven t tried it yet In this method the computer sends a digital value of half the maximum to the converter If the comparator output is unchanged the value is increased by 50 until it does Similarly if half the maxi mum value is too high and changes the comparator output Data 1 0 D to a converter Set converter output to zero Send data to d to a converter comparator output low for those new state the value is reduced by 50 until the comparator output changes back The ramp approach may then be used as before or the too much too little approach continued until the final value is reached Signal generation Signal generators such as the 8038 i c produce a range of wavelorms with variable ampli tude and frequency They depend on an RC network for timing which is good enough for general audio work but where stability and repeatability are important a crystal frequency reference is desirable Busse ah circuits are an answer but they become complicated when wide var iations in frequency amplitude and wave shape are required while retaining repeatability and stabilti
282. imes with batteries 165 00 Optional carry case 5 95 AC mains adaptor 6 95 PFm 200A Pockel 8 digit 20HZ to 200MHZ 2 band LEO display with battery O 1HZ resotution 1 mV sensitivity with battery 69 50 PRESCALERS Suitable for most types of counters o extend range Thandar BNC sockets TP600 40MHZ to 600M HZ 1OmV AMS direct powered by counter 45 00 TP1000 100 to 1000MHZ complete with AC adaptor P S 25mV RMS sensitivity 65 00 Optional probe kils suitable for all models XI 6 90 X10 8 26 r 220 240V AC input PP241 single meter A V switch 0 30V amp 30 43 PP243 3 amp version 45 65 230M Twin meter 0 30V 1A 83 00 330N 3 amp version 142 00 UK C P above models 1 00 PL Laboratory series LEO readout QMO versions series parallel etc 10A AC OC 0 5 Mag ohm PB 79 00 PL310 30V 1A 118 00 PL3100MO 259 00 PL320 30V2A 145 00 PL3200M0 315 00 LOGIC PROBES M UK C P above models 2 50 TTL OTL etc LPIDI MHZ 19 96 ANALOGUE MULTIMETERS DLPSOSOMMZ 43 44 General range mirror scale UK C P 685p UK C P either model 1 00 ANALOGUE MULTIMETERS Metrix ITT Professional range UK C P 65p Size 110 x 45x 185mm MX130 25 ranges 5000 ohms per volt 7 0C V0 110 S AC V 10V to 1000 6 0C Amps 100uA to 30A 5 AC Amps 3vA to 30A 2 ohms 1K to 10K MX230 29 ranges 20K Volt 100mV to 1000 V OC 3V to 1000V AC 50uA to 10A DC 3uA to 10A
283. in this type of output stage in typically 1W per channel The lower dissipation circuit can be readly mounted on the tube base thus reducing the load capacity to 8pF and improving performance further It is better to use the voltages onthe A second grids of the c r t to balance the cut off voltages of the three RGB electron guns The guns then operate with similar resolution defocusing at high beam currents video drive black to white grey scale tracking and input cathode loading For the regular TX 10 receiver Fig 39 lower trace was obtained by applying the line sweep to pin 10 the luminance input of the decoder chip CEDASBe1A and using a low capacitance 2 2pF X100 test probe at the output of the video drive amplifier which feeds the cathode of the green gun see Fig 37 Figure 39 centre screen shows that the colour subcarrier frequency if 6dB down In fact the situation is somewhat worse than this because in addition there is the effect of a subcarrier notch a 6MHz sound notch and a far from perfect luminance delay line before the decoder chip As it is not intended to use these three components in the modified receiver although details of them will be given later it is only necessary to consider from pin 10 luminance input of the i c TDA3561A onwards The output drive stages to the c r t cathodes plus equalisation circuits for TDA3561A remain to be considered for improvement The TX10 receiver
284. inchesters to store 10 Mbytes or more for around 4000 These machines can deal with advanced information sto rage and retrieval word process ing etc Interactive infrastructures In order to discuss some of the wider issues as we move into the Information Society it may be helpful to refer to Fig 1 which shows the forces influencing an information services infrastruc ture Technical advances are a necessary but far from sufficient Sey for progressing tow ards an information society The rate of advance will be much more dependent upon the interplay of the factors shown in the figure Exceptions like the microcompu ter may arise in special cases where successful application can be independent of most of the delaying factors wo prime forms of informa tion are shown the old tech nology that is print on paper in the form of written letters typed reports printed newspapers magazines and books and the new technology that is radio television tape or disc recordings videotex databases and information banks Asso ciated with these systems and information channels is the hard ware and software required to put the information into machine readable form process it and convert it back into human assi milable form The old technology is well entrenched It has been deve loped by trial and error since 1455 when Gutenberg demon strated the feasibility of movable type A set of compromises
285. ing the desired clock rate for best res olution is relatively simple List 4 is a program for these measure ments Hardware Some input output hardware is required for sending data to the d to a converter and for readin inputs from the comparator an timer circuits It is also useful to have spare lines for other pur poses A popular and easy to use device for this purpose is the 8255 It provides two eight bit and two four bit ports all individ ually programmable Figure 4 shows the complete interface cir cuit Decoded address lines select the 8253 and 8255 devices mem ory locations C000 to FFFF are free in the ZX81 When the circuit is active ZX81 ram needs to be disabled so the RAMCS sig nal is taken low Address lines A are decoded by gates output of which enables the 74LS138 data selector circuit This in turn selects the 8255 for A and the 8253 for A Lines Ay are inter Ls VIRELESS WORLD MAY 1984 10 List 1 Voltage measurement using the ZX81 POKE 49155 137 FOR D 0 TO 255 POKE 49152 D LETA PEEK 49154 IF A 2XINT A 2 Initialize 8255 Outputstepto d to a converter Read comparator THEN GOTO 70 Read value DO jump if 1 NEXTD PRINTD V Printresult GOTO 20 List2 Sinewave generation program Store sine values x Xincrements REM XXXXX XXXXX x No of chars INPUT X FORN 1TOX LETP 16513 N LET S INT 128 X 1 COS 2XP1 360 x N x 360 X POKEP S N
286. ingful BCTS and BRD are not used at all and on thetransmit side keying is applied to the BRTS line while BTD is held at 5V To complete the RS232 inter face the Am7910 has a DTR pin data terminal ready which acts as a sort of chip select line Held at 5V the pin dis ables the internal logic and the inputs and outputs It may be convenient to use this as a method of switching the modem on or off line All digital inputs and outputs of the Am7910 are Telephone interface The transmit carrier appears on the TC output of the Am7910 at a level of about 3dBm into 6009 In an acoustically coupled mo dem it can be applied direct to the microphone of a telephone hand set butin a direct coupled design WIRELESS WORLD MAY 1984 this signal must be fed to the same connections from which the received signal is to be extracted It is desirable to provide some degree of separation between transmitted and received signals and this can be achieved simply with an op amp duplexer Fig 3 The impedance of the telephone line is matched by the 6009 resis tor and the network introduces a 6dB loss between the transmitter and receiver In practice the line is unlikely to match the resistor perfectly and may even be quite reactive however this should not matter much Sensitivity of the receiver is very high the modem will accept signals between OdBm and 48dBm although the carrier detect pin will not turn on unless
287. ining aid these people might be able to continue their practice at home freeing the speech ther apist to deal with more sufferers The aid described in this arti cle was developed in co operation with Dr Pam Enderby chief speech therapist of the Frenchay Hospital in Bristol A survey car ried out by Dr Enderby s depart ment indicates that there are some 400 000 people in the United Kingdom with moderate speech disorders and she believes that such an aid may be able to help at least 250 000 of them Circuit design The function of the aid is to moni torthe wearer s speech analyse it for pauses and to sound a warning X Anti feedback diode e o E 4 if the pauses are absent or tm too widely To avoid false triggering by extraneous noises a throat micro phone is used The type chosen is already widely found in speech therapy departments it is very light and comfortable to wear The microphone plugs into a small plastics box containing the electronics which may be sup ported by a carrying pouch hung around the neck Since the aid is intended for remedial exercises Penk hold Comparator WWW americanradiohistorv com Timing 9V AE trigger Lad driver poem um ly P J Pickersgill B Sc and N J Stewart B Sc Fig 1 How Pausaid works C charges when the user speaks and discharges durin moments of silence If he fails to pause now an
288. intenance of satellite earth stations or broadcast transmitters or Tropo LOS MUX or PCM and digital or HF equipments o WIRELESS WORLD MAY 1984 WWW americanradiohistorv com COMMUNICATIONS ENGINEERING WIDE RANGING OPPORTUNITIES IN THE DEVELOPMENT AND MAINTENANCE OF ADVANCED VOICE AND DATA SYSTEMS In every sphere of its operations Aramco relies heavily on the most sophisticated communications links The following appointments offer invaluable experience of advanced data and voice networks together with all the tangible rewards of working for the world s largest oil producing company PROJECT PLANNING CO ORDINATING ENGINEERS 3 posts Circa 19500 25 500 net Will be involved in the planning and coordination of all types of telecommunications projects One post requires at least 10 years experience covering Transmission Systems Engineering Systems Design and UHF VHF Radio Networks and Microwave and Multiplex Applications The other 2 posts require at least 7 years in the planning engineering and implementation of telecommunications projects Experience of drawing up engineering standards and of technical writing would be advantageous for one of these posts Ref PPE 139 DOCUMENTATION ENGINEER Circa 19500 22 500 net Will head the technical writing group and must have experience in the development preparation and editing of communications related standards specifications procedures e
289. itles please enquire Computer calc etc keyboard bargains lor callers ALWAYS KEYBOARD BARGAINS FOR CALLERS 37 35 HENRY S COMPUTER SHOP 404 406 Edgware Road London W2 CHERRY KEY PAD 16 button key pad non encoded 5 17 UK C P 30p MODEM CARDS COUPLER Brand new tested answer and originate 300 BAUD uncased acoustic modem card by famous manufacturer RS232 input output Power supply 12V at IBOMA Requires 2 magnetic earpieces 2 switches 2 LEDs and connectors to complete Clrcuils and connection data supplied Card only 26 04 Card and remainder of small components 29 09 Telephone Direct Line coupler type LTU 11 MKII Suitable for direct coupling PRESTEL adaplors and the above acoustic modems Integral Line select and autodial relays requiring TTL inputs Circults and connection data supplied LTU 11 Coupler 13 00 1200 BAUD receive 75 BAUD send direct coupled modem lor PRESTEL Requires 5V supply with TTL inputs for data line select and autodial LTU 11 direct coupler required See above Connection data supplied PRESTEL modem card 13 00 STOCKISTS FOR Printers Paper Thermal Daisy wheel Disk Drives Boxed Chassis also Winchester Monitors Green Orange White Colour Micro s BBC Electron Nascom Galaxy Plus others Cables plugs blank disks amp lapes software books etc Official orders welcome Subject to confirmation Please add 159 VAT UK only Export orders at
290. jority of scientif ically educated people harbour niggling doubts about it may indicate that something some where might perhaps be wrong Moreover today s critics of Spe cial Relativity are no longer die hard but well informed reason ing and serious I am willing to wrangle with the best of them about the tradi tionally poor presentation of the clock paradox and the impossibil ity of drawing co variant Min kowski diagrams but to do so would only extend and support arguments that have been raised many times before arguments which characteristically have never been refuted without begg ing the question or even worse logical crimes by any Relativist For a selection of such tricks see Professor McCausland s nicely reasoned article in WW October 1983 Criticism of this kind takes issue with the weird predictions consequences of the theory so that one is forced to refer to argu ments mathematical or other wise within the theory itself in order to criticise it One can then always be accused of failing to understand the theory properly Naturally no relativist would ever admit that his critic might under stand the theory too well On this occasion I prefer to discuss the premises of the the ory rather than its deductions WIRELESS WORLD MAY 1984 and I shall not invoke the opinion of any third party but rely only on the written words of Einstein himself By these means I hope to present my
291. k 80OK 1 6 Megabyte on line 499 95 Opus Dual 5802D Double Sided 80 Track 800K 1 6 Megabyte on line 599 95 DOUBLE DENSITY DISC INTERFACE The ultimate Acorn compatible disc interface for your BBC micro e Utilities on ROM including Format and verify tape to disc transfer automatic 40 80 track selection automatic density selection unique mass copy routine powerful machine code operating system giving up to 248 files 80 faster than single density Easy to install Free user manual supplied 120 00 MONITORS 12 Green Screen__ 89 95 12 Amber Screen E 99 95 Lead to conneci to BBC Micro 3 95 Ex stock delivery e 24MHz Bandwidth Limited quantity 14 JVC Colour Monitor Med Res _ 187 39 14 JVC Colour Monitor High Res 279 39 THE ORGANISER DESK e Top shelf for Monitor Printer Large Desk Top Area e Lower Shelf for Paper Book Storage e Teak Finish On Castors e Self Assembly e Ample room in front of the shelf for you to sit comfortably Only 59 95 FLOPPY DISCS 3 Cartridges 5 75 each or 25 95 for 5 51 4 Discs with full 5 year warranty free plastic library case S SS D 19 95 for 10 S SD D 23 95 tor 10 D S D D 26 95 for 10 8 Discs 5 SS D 21 50 M SD D 28 50 D S D D 29 95 GOVERNMENT amp EDUCATION DISCOUNTS GIVEN QUANTITY DISCOUNTS GIVEN DEALER ENQUIRIES INVITED OPUS SUPPLIES LTD 158 Camber
292. l 0223 358757 Telex 995801 and many more CIRCLE 050 FOR FURTHER DETAILS RADIOCODE CLOCKS irottems ATOMIC TIME FREQUENCY AND SYNCHRONISATION EQUIPMENT E n 7 NEW PHASE MODULATION SYSTEMS ane ener a B Vg qox Until recently atomic time and date information was only available on v l f eee e b n transmissions using amplitude modulation The RCC 8000AM series of NN ee idm sant issn Ae ey a equipment uses these transmissions to offer high noise immunity and high accuracy particularly at very long range The new RCC 8000PM series of equipment uses for the first time phase modulated tranmissions with massive radiated powers of up to 2 Mega gy 000 ih a eas Sena Ae n amp Watts to offer long range excellent noise immunity and no scheduled ees ry Ale maintenance periods RAMONE OLODE ROC eOo0 i area wo fATMOCOOR COCR BES HOON NEW PRODUCTS The AM and PM series of Radiocode Clock equipment has been further expanded to include seven new models from top 8000S combined clock frequency standard and optional stopclock Internal standby power supply with dual rate constant current charger Time event log prints hours minutes seconds milliseconds and day of year on receipt of a log pulse Speaking clock time announcement or audio recording Slave controller total control of single standard master slave systems ie one pulse sec Dual standard slave contro
293. l 20MHZ portable with OC offset and alternate magnilier 375 00 V302F 30MHZ dual trace laboratory portable 5 CRT 369 00 V422 Dual 40M HZ portable with OC offset and alternate amplifier 580 00 V203F Qua 20MHZ lab portable with sweep delay CRT 375 00 V650F Dual 60MHZ tab portable with dual lime base 850 00 Also In stock V134 storage VC6015 digital storage scopes Battery Mains Scopes Vector amp TV monitor available 3030 Single trace ISMHZ 5mV 95mm CRT plus component lester 154 00 3132 Qual 20MHZ 2mV 5 CRT Algebraic Z mod plus component comparator and OC source outputs 283 00 3034 Battery mains dual trace 15MHZ 5mV 95mm CRT algebraic 400 00 2 years warranty 60523108 Single trace OMHZ 5m V 75mm display mains portabie 132 00 CS15624 Dual trace 1OMHZ 130mm CRT 1 mV 1 microsec with 2 probes 260 83 CS1566A Dual 20MH7 140mm CRT 5mV 0 5 microsec with 2 probes 332 60 THANDAR 2 years warrant SC110A TOR battery bench portable l mV 32 x 26mm display Sm 26 01 EE QU LC Hi 50mm 165 00 Optional carry case 5 95 AC adaptor charge 6 95 Rech Wicad 11 00 MIXED QUANTITY Scos amp EXPORT DISCOUNTS We would be pleased to quote Contact sales olfice at 406 L Please add 15 VAT UK only PRICES EXCLUDE VAT ORDER BY PHONE OR BY POST OR CALL IN AND SEE FOR YOURSELF TRANSISTOR TESTER
294. l EPROMS Copies up to 8 27 128 Serial interface internal vertical and cheap and reliable data storage Supphedin li tested prior to despatch Dimensions in typ ONLY 2 MINUTES Internal LCD horizontal tab settings standard ribbon good condition and in working order approx 14 high x 14 wide by 11 deep display and checking routines for IDIOT adjustable baud rates quiet operation plus Options Floor stand 12 30 VAT Supplied complete with circuit 240 volt AC PROOF operation ONLY 395 00 PP 3 00 J many other features Supplied complete KSR33 with 20ma loop interface 125 00 l operation ONLY 45 00 PLUS 9 50 CARR Data sheets on request with manual Guaranteed working 130 00 or Sound proof enclosure 25 00 VAT 24 CASED A ide by the KGM C ntes EIS QU optional floor stand PROFESSIONAL KEYSOARD OFFER with a similar chee at ine 13 monitor COLOUR MONITORS NOVEX NC 1414 CL Fully cased brand new Onginally used for large screen data display Very compact unit in lightweight An advantageous purchase of brand new surplus allows a great QWERTY full travel Fa ray ore nau iractions olthely orginal costs Abs Ma ad MOM E gee 14 colour monitor Many exacting features PHAMERIC 7204 60 full ASCII 60 key upper lower contro key paralle TTL icon Ele such as RGB TTL and PAL Compasile Mga output plus strobe Dim 12 x 6 5 amp 12 DC 39 50 y input make an ideal unit tor schools clubs inputs Internal speaker and audio amp
295. l less to use or nothing at all A num ber of electronic component sup pliers including Maplin Elec tronics Display Electronics Ambit International and STC Electronic Services allow cus tomers to search their stock lists by microcomputer and place orders directly In addition there is a chain of privately run bul letin boards offering facilities such as software down loading and electronic mail One problem faced by would be modem constructors or buy ers has been in deciding which transmission standard to go for Prestel follows the CCITT V23 standard sending data to the subscriber at 1200 baud and receiving at 75 baud Many other systems operate at 300 baud in each direction There is also a 600 baud CCITT standard and the situation is complicated further by the existence of yet other standards across the Atlantic some of which are used by data bases in Britain Multi mode modems have tended to be complex and expen sive but the introduction by Adv anced Micro Devices of a versatile modem chip capable of support ing all common standards has now made them a practical pos sibility for the home constructor The Am7910 is a 28 pin l s i device signal processing through WIRELESS WORLD MAY 1984 out Audio frequency tones received from the telephone line are sampled by an 11 bit ana logue to digital converter and tones transmitted are generated by an 11 bit d to a The shape of the sine wave is gove
296. lecommunications Technicians Certificate or equivalent qualification and a thorough grasp of satellite communications are essential Knowledge of major broadcasting systems familiarity with news agency transmissions and the ability to recognise a range of languages an advantage Applicants will be required to take written tests and appointment will be subject to satisfactory hearing tests Shift working involved Salary 7 867 9 761 plus a 10 shift allowance Relocation expenses considered Write or telephone immediately for application form quote ref 3222 WW and enclose stamped addressed foolscap envelope to Senior Personnel Officer BBC Monitoring Service Caversham Park Reading Berks RG4 8TZ Tel 0734 472742 Ext 212 We are an Equal Opportunities employer WIRELESS WORLD MAY 1984 WWW americanradiohistorv com gem cm u mm um me mm EB US Em om CAPITAL APPOINTMENTS LTD 1 THE UK s No 1 ELECTRONICS AGENCY If you have HNC TEC or higher qualifications and are looking for a job in design test customer service tech i nical sales or similar fields Design Engineers amp Materials Supply Control Farnell Instruments and the Electronic Engineering Department Sas alae have together established a Teaching Telephone now for our free jobs list i l We have vacancles in all areas of the UK This has provided a rare opportunity for Associates to work on Salarles te 15 000 pa I
297. lift does not continue beyond subcar rier frequency Figure 42 shows the typical overall frequency response of the TDA3561A colour demodulator chip through the RGB output stages in prac tice Fig 42 was the output response of the green drive to the tube cathode From a comparison of Fig 39 with Fig 42 it is apparent that 4 1 R LIG L 2 DL700 31 a 470 2xfsc 10Vdc Q to Trgg 10 Fig 34 Data blanking ftw 250m a 470 8 866 i MHz 22p teas o o 8 A 9V Sandcastte osve Pulse 34V 1f95V 21o4V2TidB EE 2 Colour decoder npe TT us TOASSS1A W 23 MS 3560 100n 324v amp A0mV pk pk 100 Hfor 100 colour bars 5V accref V V 2y2 330n Z22 330n fant there is some ringing at the beginning and end of each line On investigation it was found that the leads carrying RGB sig nals between the decoder chi and the tube base board whic contains the RGB output video drives transistors must be care fully positioned In the circuit condition shown in Fig 39 the rings were at a high amplitude because these leads were passing near the switched mode power supply Since the power supply chopping rate is line locked op erating at 15 625kHz magnetic field rings from the transformer can readily be picked up by the wires Figure 42 shows that with careful positioning rings at the end of the active line are greatly reduced and can be made virtu
298. ller total control of two different and independent slave systems ie one pulse sec and one pulse half min Slave distribution amplifier maximum flexibility for the largest master slave installations requiring dual standard operation multiple cir cuits and complete master slave backup POACHOXOANIN CLIAOK SOT MOOD ne amm T SSG n quae H NEW OPTIONS A continuously expanding range of fully integrated software and hardware is available for both series of Radiocode Clock equipment Standard op LAE CONTROLLER aac aoOG EF eee a Z a IRIG B precision serial o Time cod a j precision serial o p ime code generators e e amp I e ib s e RS232 V24 1mS resolution Intelligent slave systems IG OM E ee thane General purpose parallel o p Standard frequency outputs KEINE NEN FSK record replay system Stopclock operation a teri a Gay P WR Keypad entry of alarm times Calibrated systems for Keypad entry of time date increased accurac a amp 00000000008980060 m d t Deb TREES FDOT ERR A Radiocode Clocks Ltd i see v e6e009000902590000 2 j Unit 19 Parkengue Kernick Road Industrial Estate sli at ie caen ZI ee ae 25 ACH AL Penryn Falmouth Cornwall Tel Falmouth 0326 76007 A Circuit Services Associate Co CIRCLE 023 FOR FURTHER DETAILS 12 W
299. locity of light was universally constant The resulting Restricted or Special Theory of Relativity which required space and time to become distorted as a consequence of the observer s motion preserved electromagnetic theory intact but at the expense of classical mechanics and common sense Many paradoxes have ensued the one examined here which is less well known than some shows that Einstein s relativity of simultaniety is incompatible with his own Second Postulate The implication is that Einstein s arguments concerning the nature of time may be suspect and hence no longer capable by sustaining the Lorentz transformations of rendering the Maxwell Lorentz theory plausible 70 MODERN PHYSICS Here is as vivid a description as we are ever likely to read by the man on the spot of the intransig ence of preconceived esta blished ideas Poor Einstein Like everyone of his generation he had been brought up on the great Faraday Maxwell theory of electromag netism and he himself believed completely in the reality of elec tric magnetic and gravitational fields He did his best to help by proposing what seemed to be a wise balanced and above all generally acceptable compro mise Here he is writing about the crisis of 1905 retrospectively in 1952 the italics are his own Classical mechanics teaches the equivalence of all inertial sys tems for the formulation of nat ural
300. ly BRAND NEW with 90 day guarantee and FREE daisy whee and dust cover Order NOW or contact sales office for more information MOSTEK CRT 80E Brand new dual eurocard 280 based VT100 PLUS emulator with graphics etc 499 00 BA11 MB 3 5 Box PSU LTC 385 00 a Nag 1200 baua receive Data i o via RS232 D Optional extras RS232 data cable 10 00 Tech manua 7 50 Tractor feed DLV11 J 4 x EIA interface 310 00 Socket Guaranteed working with data 49 95 140 00 Spare daisy whee 3 00 Carriage amp Ins UK Mainiand 10 00 RKO5 J 2 5 Mb disk drives 650 00 MODEM 20 2 same as 20 1 but 75 baud PDP1105 Cpu Ram i o et 450 00 receive 1200 baud transmit 130 00 0 ELECTRONIC RT11 ver 3 doc kit bound 70 00 Mate ete et Ma acoustic 66 DISC N COMPONENTS LA36 Decwriter EIA or 20 ma 270 00 P 0 7 EQUIPMENT KLBJA PDP 8 async i o 175 00 Due to our massive bulk purchasing programme which enables us to bring you the best possible nc Dias de ES anaes dae bargains we have thcusands of C s Transistors Relays Caps PC B s Sub assemblies controller E Switches etc etc surplus to our requirements Because we don have sufficient stocks of any NEW DSL2123 Multi Standard modem selectable V21 300 300 bps V23 75 1200 V23 1200 75 full duplex Or 1200 1200 half ET HAS ETE Eae ATE UNES 9 one item to include in cur ads we are packing all these items into the BARGAIN PARCEL OF A MEC Equiv MSV11 L minns ee modes
301. ly more appealing Content is unchanged except insofar as it is continually changing as the subject moves forward computing for example occupies much more space than it did even five years ago But the well established features remain and will do so long as readers want them One result of adopting the new style is that the familiar perfect bound method of making the issue has gone and is replaced by saddle stitching which also means that advertisements tend to appear in unfamiliar places in the page make up part of the price one has to pay for the use of colour in editorial pages We hope you like the new appearance which is celebrated by the first part of a description of John Adams new computer His first design the Scientific Computer was extremely successful and this new development is similarly advanced being disc based and running a good deal of CP M software The new WW multi standard modem also starts this month the second design by Richard Lambley to emerge from our laboratory SS Pirate chips Encouraged by the successful tests of Plymouth Poly s ingenious satellite tv system research teams in Wireless World s laboratory block are pressing ahead with their own plans for broadcasting in the 1990s One promising idea now under development may help do away with the ubiquitous radio pirates of which the IBA complains Our researchers note that the three or four pop pir
302. m not referring to service in the maintenance sence al though an efficient service network in these days of increas ing dependence upon machines is extremely important but ser vices for supplying information The components of a service infrastructure are a communic ations network accessible to a large customer base offering cheap time independent of dis tance a customer base possess ing a range of compatible machines using standardized pro cessing and communications software and a number of information providers feeding information to the network When compatible terminals connected to a growing network reach a critical mass assuming that an adequate customer base for particular service also exists the incremental cost to a supplier mounting the nth service will be low His service will ride on the infrastructure so his direct investment involves only the injection of information CREATION OF A MARKET DRIVEN SERVICE INFRASTRUCTURE The economics and politics of telecommunications I do not intend here to become involved in the controversy about public interest state control and private enterprise Governments are of course concerned about roads medical services police railways telecommunications etc the UK governmental interest in information technol ogy has been strong because it is perceived as a way of generating new industries and services increasing exports and providing new
303. m of the components layed out on an EXP 300 breadboard Each component is labelled and the values are given in a component listing Even the row and column lettering of our EXP 300 is shown to make the location of the correct noles in which to push the components easy to find There s no soldering involved it couldn t be easier As an extra bonus there s a full circuit description and the details of a regulated power supply on the other side of the sheet Clip the coupon and get your FREE project sheet with each EXP 300 bought AND a free catalogue Just ask about our other free projects too y D PETRUS TS s BS PROTO BOARDS The ultimate in breadboards for the minimum of cost Two easily assembled kits EXPERIMENTOR BREADBOARDS The largest range of breadboards from GSC Each hole is identified by a letter number system EACH NICKEL SILVER CONTACT CARRIES A LIFE TIME GUARANTEE Any Experimentor breadboard can be snap locked with others to build a breadboard of ary size 7 PROTO BOARD 6KIT 12 00 630 contacts four 5 way binding posts accepts up to six 14 pin Dips 8 PROTO BOARD 100 KIT Complete with 760 Contacts accepts up to ten 14 pin Dips with two binding posts and sturdy base Large capacity with kit economy 1 EXP 325 2 25 The ideal breadboard for 1 chip at circuits Accepts 8 14 16 and up to 22 pin ICs Has 130 Sra contact points including two 10 point bus bars 2 EXP 350 3
304. mast or aerial system fails were underlined in the incident that put all four channels off air at Durris near Aberdeen at the height of the appalling weather conditions on January 17 While it proved possible for IBA BBC Grampian ITV and British Telecom riggers and engineers to restore service to most viewers in a matter of days some viewers remained virtually without television until February 9 Although this incident is the first time that a very large number of UK viewers have lost all services for a matter of days the collapse of the Emley Moor mast in 1969 left BBC 1 unaffected basically similar incidents have happened elsewhere Last October for example a 315 metre mast of Belgian television at Wavre serving Brussels with a considerable number of radio and two television services was blown down While a temporary substitute for the Radio 2 service used a spare transmitter at the Palais de Justice other services were lost over an ex tended period including television services of BRT 2 and RTBF 2 However a large percentage of Belgian viewers are oncable systems and steps were taken quickly to improve the distribution of programmes directly to the cable stations An electrical fire put an American tv transmitter WOWV TV in West Virginia off the air in the afternoon of January 12 Before the station could be put back on the air that night a second fire broke out completely destroying both transmitters
305. minal Tractor feed unit Va with integral stand Price with 20mA I F 295 with EIA I F 325 T100 mr Terminal Price 775 Options available VTIXXAA 20mA em VTIXXAB AV 75 VTIXXAC Printer Port 125 LOW COST VDUS Hazeltine 1500 Newbury 7008 DAISY WHEEL PRINTERS Anderson Jacobson AJ832 375 Diablo 1345A 395 TEKTRONIX GRAPHICS 6068 Monitor 4006 Terminal et H 4010 1 Terminal 1995 4015 1 Terminal 7 250 4027A Colour Terminal 1 995 4051 Desktop Computer 1 750 4052 Desktop Computer 4 950 4114 Terminal 10 500 4662 Plotter from 1 995 4952 Joystick 275 TEKTRONIX COLOUR GRAPHICS Ex Demonstration Stock in Original Manufacturer s Packaging Colour Graphics Reece Model dU Providing full colour graphics and alphanumerics Plot 10 compatible 8 displayable colours from pallette of 64 Full screen crosshair cursor 34 x 80 display 2720 characters 120 user defined patterns RS232 Interface with up to 9600 baud transmission Original List Price 9 500 a ers Our Amazing Price stig Ts j Only 1 995 n A copy of our Trading Conditions can be supplied on request ADD 15 VAT TO ALL PRICES Carriage and Pack ing extra Electronic Brokers Ltd 61 65 Kings Cross Road London WC1X 9LN Tel 01 278 3461 Telex 298694 P ee a l a Z Electronic Brokers WWW americanracdiohistorv com m 18 COLOURTET 132 7 COLO INTEGRE
306. mon sense have been politi cal The PTTs have rigidly applied their carrier monopoly nlike the situation in the US no other organization has been per mitted to arrange communication links between service and cus tomers for instance so that peo ple with terminals can obtain information from a database running on a remote computer In 1979 an electronic journal was running in the United States and the organizers planned an experiment to connect terminals for editorial services and contrib utions from the UKto the system WWW americanradiohistorv com British Telecom BT could not provide the interconnection and it was planned to use the com mercial network Telenet which had a node in the UK requiring connection to terminals via BT lines The experiment had to be abandoned because BT vetoed the participation of Telenet as a third party carrier Note that if Telenet had been offering an electronic journal to UK partici pants that is if it had owned the journal s computer and facilit ies in the US and was using its network to link its own customers to the system then it would not have been acting as a third party and the veto could not have been applied The question is can the exist ing networks be coalesced to pro vide the needs of the information society and how long is it likely to take The critical mass problem mentioned previously could of course be resolved by further separatio
307. n 2 50 120 ohm 34n dia 1 EMI 13 2x8in Bass amp Tweeter 4 or 8 ohm 10 watt 8 pp 1 RADIO COMPONENT SPECIALISTS 222i visione sono crovmos Books and Components Lists 32p stamps Minimum post packing charge 65p Access or Barclaycard Visa Tel 01 684 1665 for SAME DAY DESPATCH Cash prices include VAT SINGLE BOARD 6809 2nd PROCESSOR FOR THE BBC MICRO PROVIDES A LOW COST DEVELOPMENT SYSTEM FOR INDUSTRIAL APPLICATIONS Sits inside the BBC or plugs into an extension rack Enables standard Flex format Discs to run on BBC Supports High Level Language Compilers Cross Assemblers and Disassemblers for most micros Connects directly on to the tube 64k DRAM on board Two 28 pin byte wide memory sockets Acorn Bus compatible DIN 41612 Bus interface Also available as a single board controller 11 St Margarets Road Cambridge Girton Cambridge CB3 OLT Microprocessor 0223 276791 Systems Limited CIRCLE 074 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 21 www americanradiohistorv com m 4 4 w D BR A New Concept in Optical Equipment The Fibre Optics Educator is a low cost versatile instrument designed primarily for organisations involved in or about to enter the field of fibre optics It can function as TEST EQUIPMENT e g for accurate fibre attenuation measurements to a range of 50dB optical level measurements and for testing out analogue and digital optical transmitters and rec
308. n scious support of Lorentz although ostensibly from a new and independent standpoint Ein stein argued thai if the velocity of light were universally constant en those very same mathemati cal distortions of reality the Lorentz transformations must actually take place for that was Saved Maintained without the need for agonising re appraisal and re formula tion from revised first principles There are good reasons for avoiding that extreme process the only way the velocity of light could be the same for everyone as he had assumed it to be And in order to save the electromagnetic theory which had already been disproved his colleagues bought the idea That is how it all happened It was a grand cover up operation and the people who pulled it off were acclaimed as heroes The trouble was that their desperate and successful defence of the electromagnetic theory soon led in 1925 to far worse difficulties Maybe someday we shall come to wonder if their success was really worth the troubles it has caused In the meantime let us try to find out whether there is any possibil ity that the Special Relativity con cept might be true Einsteins s second postulate The precedent that Einstein said he had taken over from the theory of Maxwell Lorentz was that the velocity of light is a constant of Nature The electromagnetic statement was c 1 k u constant where c is the
309. n Suffolk IP16 4HT ELECTRONICS Tel 0728831131 CIRCLE 082 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com J P lpr ELECTRONICS NEW WHOLESALE PRICE LIST AND CATALOGUE NOW AVAILABLE HUNDREDS OF COMPONENT LINES AT COMPETITIVE PRICES AVAILABLE FROM STOCK CAPACITORS RESISTORS PRESETS CERMETS RELAYS BUZZERS Ni CAD BATTERIES DIODES BATTERY HOLDERS EDGE CONNECTORS MINIATURE SWITCHES 7 SEGMENT DISPLAYS POWER SUPPLIES MAINS FILTERS IDC CONNECTORS FUSEHOLDERS INVERTERS A B S BOXES MOTORS SPEAKERS WIREWOUNDS CABLES TRANSFORMERS D CONNECTORS TRANSISTORS FERRITES AND MUCH MORE WRITE OR TELEPHONE NOW FOR A FREE CATALOGUE TRADE ONLY JPR ELECTRONICS UNIT M KINGSWAY INDUSTRIAL ESTATE LUTON LU1 1LP TELEPHONE LUTON 0582 410055 TELEX 925859 JPR CIRCLE 059 FOR FURTHER DETAILS Brand NEW amp EX DEMO surplus BARGAINS SELEX Model 75SC COPIER Plain paper office copier with dry single component toner 12 copies per minute 395 00 No warm up time Microprocessor controlled with keyboard entry PHILIPS P2000 SYSTEM comprising 280 based processor 24 x 80 green display Twin double density 5 disc drives B i Built n DIGITAL cassette drive ITT Model 3510 TELEFAX K Group 2 facsimile transceiver tor sending reproductions of documents
310. n by open collector drivers 1 When M1 and IORQ are both active the processor is inviting a peripheral device to supply part of an interrupt vector interrupt acknowledge Table 2 Data bus driverlogic NO Om WD 40 Condition Bus buffer drives 1 0 write towards bus 1 0 read towards Z80 System memory write towards bus System memory read towards bus External memory write towards bus Externai memory read towards Z80 Interrupt acknowledge towards Z80 features of its operation before describing the external circuits Modern dynamic memories use a multiplexed addressing tech nique where the address is split in two in this case eight bit parts This reduces the number of add ress pins on the i c from 16 to 10 eight address pins and two strobes to latch the address bytes into the memory A prime consideration here is that this reduces the package size and hence the cost but it also allows the memory access to be broken into two stages with consequent benefits Consider a 64K bit dynamic memory to be a matrix of memory stores 512 by 128 each row of 128 being connected to a single bus line Each store is a minute capa citance connected by gates to these lines When the first part of the address known as the row address is latched into the mem ory the highest bit is stored and the other seven are decoded to decide which of the 128 cells in each of the rows should be con nected to the bus line for th
311. n rather than coalesc ence In other words new separ ate networks appear for inter connecting information sources and customers because this group regards the value of the particular kind of information received to be worth the relatively high price they have to pay to sup port the facilities The services available to stockbrokers in the City of London are an example A possible compromise would be multiple interconnected networks each free to innovate a huge unified network would tend not rapidly to adopt communica tion new technology but with common interconnection stand ards and a payments clearing house mechanism To be continued WIRELESS WORLD MAY 1984 TEK PORTABLES THE ANSWER BY ANY MEASURE From the long line of success the affordable today s portable oscilloscopes the 2465 and 2445 provide probe tip bandwidths of 300MHz and 150MHz respectively On screen cursors allow the immediate and precise determination of voltage time frequency ratio and phase with CRT readout of results The 2400 oscilloscopes have The 2200 s The 2300 s four independent vertical channels The four low cost oscilloscopes in Compact and lightweight these two of which are optimised for logic this group offer unprecedented 100MHz oscilloscopes are signals Facilities are also provided value in initial cost and inherent ruggedly built to withstand tough for accurate delay matching high reliabilit
312. n the bag would nnormally condition conversions etc pcb DIM 15 x 4 5 2495 Carriage on keyboards 3 00 exacting user Brand new and Fully Guaranteed GRAB BAGS RAND EW AT ONLY 499 VAT Join the communications revolution with our MMM if diodes bridge recs etc etc All devices tor 24 hrs per day Units are made to the FP1500 25 features a 50 2 95 100 3 13 and working condition with data Permission print mechanism givirg I C s enables us to offer 100 mixed R or CALL Processor electronics cost to buy Fully guaranteed all I C s full up to 300 baud full duplex ANSW j A modes AUTO ANSWER Data i o via offer full DIABLO QUME a fracti spec 100 6 90 200 12 30 300 19 50 standard RS232 25 way D socket Just 2 wire f Command compatability ion of its s oy PN connection to comms line Ideal networks etc fand full control via CPM Wordstar etc original cost 4 rs Complete with data tested ready to runata Many other features include bi directional St t DEC CORNER NEW SUPER LOW PRICE of ONLY 63 00 printing switchable 19 or 12 pitch ful width 381 mm paper handling with upto VAT Carr MODEM 20 1 Compact unit lor use with MICRONET PRESTEL or TELECOM GOLD etc 2 wire uirect connect 75 baud transmit 163 characters per line friction feed rollers for singte sheet or continuous paper internal buffer standard RS232 serial interface with handshake Suppiied absolut
313. nal and a fourth audio track is an alternative Where optional sync head is used vertical intervalis recorded separately b without overlap Effect of interlace is to record two types of field Two field sequence repeats endlessly Addition of chrominance to interlace sequence causes sequence to extend see appendix Audio SSM LAPSED SESE FEE PIRSA AI EAN OD ASINI SIE eA SEI M e m T LRL MN VER CAMBIO ORE SOT IERI REVENU SIS gee ELD Ea is Ga eee ee eee Field 1 vertical interval 239 8mm sec Field 1 Field 2 vertical interval Alternative formats Recorded by optional syne head on drum amp 25 Vpulse Jj amp 15 16 17 Field 1 recording 55 36 7 18 19 etc 212 puse 1326 327 2e 329 L312Y 328 329 330 331 ete Optional sync head recordings WWW americanradiohistorv com Track angle 2 33 44 4 Field 2 s Control track 1pulse field Audio 4 X Audio3 etc t 3 31255 Field 2 recording b Typical playback head switch points etc 62 625 1 ku Fig 2 Effect of HE error on playback signal Signal amplitude in a and c is identical despite sense of tracking error Maximum signal occurs with correct alignment as in b Fig 3 Simple single bimorph at a changes head contact angle At D compound bimorph closely approximates parallel action Tracking head mounted in vide
314. nd which started around 1978 IBM inp E uA incorporating the 11 flo sc in To71 gerunt announced copies almost imme diately but in September 1972 IBM announced the 3740 data entry station incorporating a diskette and a host of competi tors followed 6 In 1975 Gary Kildall wrote some software for controlling files stored on a floppy disc He was asked by msai a floppy disc supplier to design an operating system for them and the first ver sion of CP M 1 3 became available Hardware dependent functions were concentrated in one section of it enabling it to be adapted for use with microcom puters using the 8080 and later the Z80 c p us Kildall founded Digital Research in 1976 and more versions were released later including one for 16 bit machines CP M 86 Microcomputers with CP M and floppy discs offering up to 1 Mbyte were manufactured at rea sonable prices and the business microcomputer was born A paralel development started with the IBM Ramac hard disc introduced in 1956 but in 1973 IBM announced the WWW americanradiohistorv com 3340 Winchester Disc a sealed unit with the heads flying 20 mic roinches above the disc surface In 1978 Shugart announced the SA4000 Winchester for micro computers and in 1980 Seagate introduced a 5 Mbyte 5 25 inch Winchester selling for 925 Tan don replied in 1982 with the same unit for 400 and microcompu ters can now be purchased with built in W
315. ng the use of a pair of back to back diodes to clean up the signal This could be of use in cassette loading The program has been successfully tested with both versions of the ZX81 r o m Brian Bailey Pinehurst Data Studios 69 Pinehurst Park W Moors Wimborne Dorset BH22 OBP WW 223 T COMPACT DIRECTION FINDER Aradio direction finding system the DF2 gives an instant readout of the direction of a signal both as a digital display and as points around a compass The signals are collected from four identical antennae mounted in a square array These are combined ina head unit which phase modulates the signal with a special waveform the extra phase modulation carries the information about the direction of the incoming signal In the unit this additional modulation is separated from any other modulation and processed to give two voltages one proportional to the sine of the bearing angle and the other to the cosine These voltages are digitized and the e 3 ES A wc uu amp 7 MUN calculation to the bearing is handled by a Z80 processor which is also used to drive the display The phase shift cause by signal delay through the receiver is automatically compensated for to give a superior performance than that in most Doppler shift direction finders according to the maker The DF2 is designed to be easy to install and use In normal operation the unit instantly indicates the bearing of the rec
316. nge LCD 157 00 Megger Gen 116 40 Batt Megger 85 50 AVO 2001 91 60 P amp P 2 VAT 15 BURGLAR ALARM Ultrasonic tooks like a Speaker 99 00 Just plugs in Expandable Loud siren Exit Entry delays e Recharge batts ELECTROSIL TR4 5 RESISTORSE1 100 12 20 33 47 75 390 430 51002 560 tk 1k1 1k3 1k6 1k8 2k 3k 3k9 15k 16k 24k 27k 39k 56k 82k 100k 110k 120k 14 10 18 01 24 52 30 23 36 18 voz 1000 1500 2000 6000 L 115 or 240V sec onty 400 440V ISOLATORS 400 440 to 200 240V CT VA Price P amp P 60 9 50 1 80 100 11 08 200 200 15 68 2 25 250 18 97 240 350 2 70 2 95 4 00 5 00 0A OA 60 30V or 30 0 30V Pri 2x120V 2x30V Tap Secs 6 8 10 12 16 18 20 24 30 36 40 48 60 Tove Gan 24 0 24 or 30 0 30V VA Price P amp P V Price P amp P 80 4 84 140 410 150 648 150 ERE 1184 200 920 130 13 30 224 4330 200 2200 280 1515 220 2837 320 1916 220 4214 400 2186 265 3000 7 164 480 s 300 5000 10830 A 4122 CASED AUTOS 24A 2V or 12 0 12V 240V to 115V USA skts 2x12V Secs Pri 240V MINIATURES VA Pa 12V 24V Price P amp P 20 03A 15 24 90 SecV A Pri 80 1 319 120 3 03 2A 3M 150 4 25 120 6x2 lAx2 345 1 250 491 160 9 09 1 259 500 160 9x2 33x2 241 1000 1 60 89x2 5x2 336 2000 180 89x2 1Ax2 427 190 15x2 2Ax2 241 150 350 500 1000 1500 2000 Z80A CTC 7812 reg Z80A CPU 6522 PIA 2 99 3 70 350 1000 2000 3000 6000 81 12 1
317. ngs and widely spaced typescripts but we would rather have scribbles on the back of an envelope than let good ideas be wasted Submissions are judged on originality or usefulness not excluding imaginative modifications to existing circuits so these points should be brought to the fore preferably in the first sentence Minimum payment of 30 is made for published circuits normally early in the month following publication CIRCUIT IDEAS Combination lock with deterrent This electronic lock operates on entering the correct four digit combination on a hexadecimal keypad but should an incorrect entry be made a further entry is not permitted for one minute Each subsequent incorrect entry increases the entry inhibit period by one minuteup to a maximum of 15 minutes after which the delay period is reset Inputs A H of shift registers IC are used to set the combination and A D inputs of counter IC set the combination size four in this case Pressing the internal clear key resets the control sequence counter IC and control pulse generator IC On pressing the enter key positioned externally on the keypad outputs of decoder IC and counter IC are enabled through bistable IC Activating X loads the combination size into counter IC loads the keyword into shift registers IC 2 clears previously entered trials in registers IC CK KYBRO enable and resets the open signal of bistable I
318. nitor 99 UV141 EPROM Eraser with timer 78 GP100A 80 column printer 225 GR1 Centronics interface 65 VAT should be added to all prices DISTRIBUTORS REQUIRED GP Industrial Electronics Ltd EXPORT ENQUIRIES WELCOME Tel Plymouth 0752 332961 Telex 42513 Unit E Huxley Close Newnham Industrial Estate Plymouth PL7 4JN WW 002 FOR FURTHER DETAILS WWW americanradiohistorv com P8000 THE PRODUCTION PROGRAMMER THAT HANDLES ALL NMOS EPROMS Checks Programs Compares up to 8 devices simultaneously Handles all NMOS EPROMS up to projected 128K designs with no personality modules or characterisers See list Easy to use menu driven operation for blankcheck program verify illegal bit check checksum self test Constant display of device type mode and fault codings Individual socket LED indicators for EPROM status Comprehensive EPROM integrity checks Illegal bit check data and address shorts constant power line monitoring Full safeguard protection on all sockets Automatic machine self test routine RS232C interface supplied as standard Powered down sockets Cost effective price 695 VAT Available from stock Write or phone for more details DISTRIBUTORS REQUIRED Unit E Huxley Close Newnham Industrial Estate Plymouth PL7 4JN GP Industrial Electronics Ltd WWW americanradiohistorv com 2104 2108 2716 3 2508 2758A 2758B 2516 2716 48016 2532 2732 273
319. ns were assumed to be in place Reading this article again I see that I took a rather gloomy view of the tech nological future Information is a curious and unique resource It is unsatisfac tory to call it a commodity You cannot evaluate it until you have obtained it once you have it it may be almost impossible to eval uate in monetary terms but on other occasions there may be no doubt about its value ask a dealer on the money market about the value to him of timely accurate information The value of a train time table to a man standing on Paddington station who wants to get to Penzance is obvious It is equally clear that the same information displayed to a Martian is valueless Informa tion is destroyed when consumed and so has no scarcity value in the usual sense and yet the meaning of the phrase there is a scarcity of information about the effects of video nasties on crime is per fectly clear Information is obtained for pleasure and entertainment for monetary gain or the acquisition of power or simply to satisfy curi osity but nearly always it has to be moved before it 1s changed from mere data into knowledge These days transference often involves using an electrical rather than a paper based system The idea of an The Informa tion Society was implicit in Fritz Machlup s work in 19622 In 1974 Marc Porat in an unpublished paper analysed occupations in the United States and concluded that 509
320. nt Sutton Surrey SM2 5AS Telephone 01 661 3248 Subscriptions Oakfield House Perrymount Road Haywards heath Sussex RH 16 3DH Telephone 04444 i 459188 Please notify a change of address USA 49 40 surface mail 102 60 airmail Business Press International USA Subscriptions Office 205 E 42nd Street NY 10017 USA mailing agents Expediters of the Printed World Ltd 527 Madison Avenue Suite 1217 New York NY 10022 2nd class postage paid at New York O Business Press International Ltd 1984 ISBN 0043 6062 WWW americanradiohistorv com Editor PHILIP DARRINGTON 01 661 3128 Deputy Editor GEOFFREY SHORTER B Sc 01 661 8639 Technical Editor MARTIN ECCLES 01 661 8638 Projects Editor RICHARD LAMBLEY 01 661 3039 News Editor DAVID SCOBIE 01 661 8632 Drawing Office Manager ROGER GOODMAN 01 661 8690 Technical Illustrator BETTY PALMER Advertisement Manager BOB NIBBS A C I I 01 661 3130 BARBARA MILLER 01 661 8640 ASHLEY WALLIS 01 661 8641 Northern Sales HARRY AIKEN 01 661 8861 Midland Sales BASIL McGOWAN 021 356 4838 Classified Manager BRIAN DURRENT 01 661 3106 IAN FAUX 01 661 3033 Production BRIAN BANNISTER Make up and copy 01 661 8648 Publishing Director DAVID MONTGOMERY 01 661 3241 The list of International Agents and the Advertisers Index can be found at the back of the issue i i j i TELESCOPIC
321. nt and stock for loud speaker manufactur ing cheap for clearance 0924 170757 2540 FERROGRAPH CONTINUOUS loop cassette 10 BBC Type Garrard 301 29 Low ohms resistance bridge metre 29 Single to three phase converter Binocular prismatic lab microscope 145 Fibreoptic ligt source 35 Semi conductor tungston to white light correction mirror 2 50 Carbon filter inserts 8 Ten KT 66 and two KT88 valves 48 Monocular microscope Experimental laser mirror pairs 5 75 pair New microscope lenses Pipe bender with four sets of dies 55 Flexible pipes with BSP couplings and adaptor 3 50 ea air etc Advance cable test set 0 6000v 59 Lightfast screen inks for semicon ductor IC design and production Nerve amp mus tard gas detection equipment 20 Quantity of items used in semiconductor design and manufac ture PCM equipment FM AM generator 89 Sweep amp RF generators 040 376236 1627 WIRELESS WORLD MAY 1984 Classified Electronic Test Engineers Racal Radar Defence Systems part of the Racal Electronics Group is undergoing a period of rapid growth To meet our increasing production demands we need to recruit anumber of Test Technicians and Test Engineers at the following locations in Surrey New Malden Chessington and Hersham and at Leicester The Company manufactures a wide range of products aimed principally at the Defence Industry including radar early warning and guidance system
322. nter Parallel i f ONLY 149 17 50 P amp P Computhink Act 800 Computer system Dual floppies 2 4Mb with Qume Sprint daisywheel and lots of business software ONLY 1 200 Diablo 630 Daisywheel printer RS232 NEW 599 15 P amp P Diablo Hitype 2 Daisywheel Tractor unit S H 399 15 P amp P BECKENHAM PERIPHERALS LTD Callers welcome 01 778 3600 SAE for LIST by appointment 124 Lennard Road Beckenham end enquires Kent BR3 10P CIRCLE 019 FOR FURTHER DETAILS RADFORD Audio Measuring Instruments Audio Amplifiers Loudspeakers and Loudspeaker Components for the professional and enthusiast RADFORD AUDIO LTD 10 BEACH ROAD WESTON S MARE AVON BS23 2AU TEL 0934 416033 CIRCLE 011 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com te ett m p RC Ei p BH Generation PM2518X Jortftabpie m Lj Multimeter v f RAHANG AN FEL miai 2LIV b em m s an 5 ue T 1 E a ay ES s Ste el EMI 3 LI Electronic Brokers bring you the PM2518X an exciting new development in electronic test and measuring The PM2518X is a hand held digital multimeter with accuracy and performance equal to more expensive bench models An outstanding feature is the Electro Luminescent Display which automatically switches itself on in the dark invaluabie when taking readings in dimly lit areas The PM2518X also offers autoranging 20 amp current range tru
323. nto any arbitrary direction There were no moving parts or relative motions within the Michelson Morley apparatus Similarly the reflection of radar signals from fast moving earth satellites can be interpreted in two ways one that makes sense and another that doesn t need less to say the way that doesn t make sense is the one that assumes the velocity of light to be universally constant but that fact doesn t measure the velocity of light All manner of laboratory experiments have been pro posed and performed but always the quantity measured tums out to be not c itself but some associated parameter The canonical support for Einstein s pone lies in the aamen of de itter 1913 that light signals from spectroscopic binary stars take the same time to reach us irrespective of the motions of their sources yet there are several cases on record in which the spectra of such systems are said to break up or to show inconsistent centroid velocities both effects to be expected if c is not universally constant Apart from de Sitters argument there exists no experimental support for the universality of c It is WIRELESS WORLD MAY 1984 C assumed to be true becasue Spe cial Relativity theory demands its truth whichis as circular an argu ment as you will find anywhere There is no definitive evidence either way So now we have reached this situation to save the Maxwell Lorentz electromagnetic theory w
324. o 49157 for counter one 49158 for counter two 49159 for control Tabie 1 Control word Table 2 Control word format for the 8253 format for the 8255 counter timer Bit Function g Bit Function ata Set flag Sel mode zero Counter No PortA Port C upper Sel modezero PortB Port C lower Read Load Mode No O NWOAGON Oo 000 4 D T 0 0 1 1 1 1 1 0 oe m md a j oooo 0 4 Bin Dec Decimal data 137 Data word Note Logic level 1 data sets port in decimal 54 118 176 forinput logic level 0 for output List 3 Squarewave generation POKE 49155 137 Initialize 8255 INPUTF Fisdesired frequency CLS LET N 1 000 000 F LET M INT N 256 l s b LETL INT N 256 M X 256 m s b POKE 49159 54 8253 Control POKE 49156 L l s b POKE 49156 M m s b 100 PRINT 1 000 000 INT N HERTZ Print actual frequency 110 GOTO 20 Next frequency List 4 Frequency counter timer program POKE 49155 137 Initlalize 8255 POKE 49159 54 POKE 49156 232 POKE 49156 3 POKE 49159 118 POKE 49157 208 POKE 49157 7 POKE 49159 176 POKE 49158 225 T full count POKE 49158 255 LET A PEEK 49154 2 read port C d IF A 2 XINT A 2 THENGOTO 110 wait for D 0 LET A PEEK 49154 2 read portC D IF NOT A 2 x INT A 2 THEN GOTO 125 waitforD 1 POKE 49159 128 T 1kHz T T 1s LET X PEEK 49158 LET Y PEEK 49158 CLS PRINT 65536 Y x 256
325. o drum is shown at c Fig 4 Top dither waveform which causes head to oscillate across track At a is optimum alignment showing frequen doubling in r f envelope Wi head above track centre as in b r f amplitude increases as head reaches lowest point whereas reverse applies in case c n NN i ee A ae VARIABLE SPEED VIDEO Ampex use the term Automatic Scan Tracking whereas Sony s description is Dynamic Tracking Essentially the playback video head can move at right angles to the tape track and forms pa ofa position servo and as with all servo systems a posi tion error is required The system used differs completely from those used in track following disc drives Figure 2 shows three configur ations of head to track and corre sponding output Video recor ders use f m recording to cater for the wide bandwidth of the sig 56 Compare phase of envelope modulations nal and the waveforms in Fig 2 correspond to the r f envelope of the f m carrier Case a and case c display the same output although the tracking error is in the opposite sense Simple pro cessing of the r f level thus only provides the magnitude of the tracking error not the sense To extract the sense of the tracking error a ditheris superimposed on the tracking head which is driven by a piezo electric bimorph mounted in the drum asinFig 3 In the interests of good head to tape conta
326. o the new system only printed boards ending up on the scrap heap Getting rid of fast flyback should also significantly reduce the fire hazard of tv receivers and greatly increase reliability The prospects for international co operation over programmes and for tv globe trotting would obviously be much enhanced if there was a single universal system The co operation of all nations is really needed in order to evolve the best possible system and to get it universally accepted H G May Barton on Sea Hants Double the line standard and you are likely to end up with twice the voltage across the deflector coils unless you abolish flyback and have a zig zag scan WWW americanradiohistorv com ISHIFTINGWAVES I wonder if any of your readers could explain to methe odd behaviour of u h f transmissions which I outline below To receive domestic television signals from the Sandy Heath transmitter a simple half wave dipole with a sheath balun is positioned at an anti node in the standing wave pattern which the transmissions set up in a rectangular brick enclosure of approximately 6X4X21 metres Sometimes referred to as a sitting room While the anti node positions for BBC 2 ITV and C4 are practically coincident that for BBC 1 displaced from them by nearly 50 cm Since the point of transmission is the same for all four and the wavelength variation trivial it is difficult to understand this An attempted analysi
327. o2 01y 0Ly LOL q AS aq pynoys suid omy esau 4 eZ sud Joy 4dadxa jaj DJnd ui paj3auU0 3JD AS4 2L 9 ZARO OY ogay SJ1 91 gau Ajddns Ag ay 04 pa43auuo JO uado 443 3q UDI pesn jou Suld 39 MAY 1984 WIRELESS WORLD WWW americanradiohistorv com Table 1 Bus connections SPECIAL FEATURE Row Pin Row Function A c GND 1 GND 5V 2 5 DO 3 D1 4 D2 5 nae D3 6 INT D4 7 NMI D5 8 HALT D6 9 MREQ D7 10 iOR AO 11 RD A1 12 WR A2 13 BUSAK A3 14 WAI instruction A4 15 BUSR A5 16 RESET A6 17 M A7 18 RFSH A8 19 MEMDI operation A9 20 A10 21 A11 22 A12 23 CLK A13 24 A14 25 A15 26 27 28 29 12 30 12 5 31 5 GND 32 GND Z80 maskable interrupt line Z80 non maskable interrupt line Z80 has executed a HALT instruction Z80 is performing a memory operation Z80 is performing an input output operationt Z80 is requesting data fromthe bus Z80 is writing data to the bus Z80 has relinquished control of the system T Z80is being asked to extend the current Q Z80isbeing askedtorelinquish system control 20us pulse generated when RESET is operated 1 Z80 is fetching an op codet Z80 is performing a memory refresh cycle Non system memory is to be used for this VDUSEL Character v d u is mapped into memory System clock from processor board Note address and data A and D lines are active high These lines havea pull up resistor on the processor board and should be drive
328. om Ferguson TX 10 switch mode power supply see text Pr n a Ji this Nine a gt l T onn KS 109 1525 25 45 98 5 75 B5 MHz olour subcarrier of trace centre pnrrmmR Aj Vl ete Vid NES m Yi T V ALL aura i Spe thse as shown n Fig 3 MALE a HH w V Lat WWW americanradiohistorv com Fig 39 Top trace is the luminance sweep 0 5 to 8 5MHz applied to pin 10 of the TDA3561 A decoder chip Lower trace is the signal at the tube cathode pin 2 showing loss in response at high frequencies in the decoder chip and the video output drive circuit Fig 42 Typical frequency response of TDA3561A colour demodulator chip through to the RGB output stage This was the green drive to the c r t cathode Fig 43 Video sweep showing output of modifier comb board with the subcarrier notch retained by the f e t gate connected to 12V rail modifier turned off 33 Fig 40 Colour decoder chip and surrounding components The chroma and luminance inputs are taken from the additional board Fig 34 Remote brightness 100k Q 10k 120k Remote O control Sandcastle 10k 47k Remote saturation 5 l From Thgif Fig34used i Chroma in Burst approx 250mV From Caq R gif Fig 34 usedi u am Ao 34 nw americanracdiohistorv com m in oO 10 TELEVISION response The capacitor and the inductor resonate so that the
329. omer Electronics 0762 39818 E S I 0256 57166 Lock Distribution 061 652 0431 Phoenix Airdrie 0555 892393 Pronto Electronics 01 554 6222 Semiconductor Specialists 08954 46415 Solid State Supplies 0892 34366 Steatite 021 454 2655 Transworld Scientific 0494 36381 United Components 0494 444712 CIRCLE 078 FOR FURTHER DETAILS WWW americanradiohistorv com OV Aie Used test equipment colibrated to Manufacturer s original picos ton All this for 995 vat Fully calibrated and guaranteed for one year A multi function combination of items comprising a high performance 50MHz dual trace dual delayed timebase oscilloscope a 4 digit auto ranging multimeter and a 7 digit 1OOOMHz frequency counter TEKTRONIX model 455 Oscilloscope 5OMHz bandwidth dual delayed timebase dual trace PLUS PHILIPS model PM2517 4 digit autorange multimeter light weight battery operated AC DC volts current amp ohms PLUS PHILIPS model PM6668 7 digit microprocessor controlled frequency counter Operates to 1000MHz Full Details Available on Request ORDER NOW WHILE STOCKS LAST Carston Electronics Ltd 01 267 5311 Shirley House 27 Camden Rd London NW1 9NR Telex 23920 m q Contact us for a cash quote on your under utilised test equipment 4 Carston uy Carstome ss E AR UAE UU E eiu EUER ise S SL GREGA NS SN I WWW americanradiohistorv com Tv hazards The problems that can arise when a television
330. on is slower to gain acceptance The interval between these although private Viewdata type events for technical and political systems are making progress reasons may be many years but eleconferencing is still in its new technology announcements infancy and soareelectronicjour inspire speculative articles in the nals but electronic publishing is press which prompt discussion advancing Electronic mail was and awareness and new products much discussed in 1978anditstill or services get talked into exist is today implementation lags ence The rate of progress in speech Euronet and a set of separate recognition has been slow alsoas European PTT telecommunic predicted ations networks are expected to I think my end of term school become a unified network by report should read Forecasting about 1985 15 years after the very fair Cawkell should try pioneering work with ARPANET harder However it is no worse in the US It took about 10 years than most other forecasts and before working local area network rather better than those men LAN systems were installed in tioned below any quantity following the deve s lopment of the ALOHA network Wild forecasting The next transatlantic cable MU A will bethe optical fibre type The Before considering the likely rate idea of optical fibre communic of formation of a telecommunic ations was first mooted in 19665 ations infrastructure the back and the development of more effi
331. on Ardenne in the 1920s Technical advances have been rapid in image processing systems but facsimile machines of rather low resolution have been available since the 1930s After the war machine compatibility was the problem The interval between the introduction of the first usable machines the evolu tion of standards and fairly widespread use in business was 50 years The development of Teletex a system for transmitting text rapidly between telex replace pm processing machines is progressing slowly and micro forms around since the Franco Prussian war are still not widely used I conclude that a significant new development in information technology usually takes at least 10 years Tron point A in time to point B where B is useful small scale application Point A the starting date is hard to define It is not so much that something significant actually happens on that date but that a preliminary accouncement about Widgetisors gets transformed into a report not in this journal that Colos sus Systems Ltd are believed to be considering the construction of a new factory for the produc tion of Widgetisors The infor mation technology industry is skilled in convincing us that only fossilised people can afford to ignore imminent developments which may still be a gleam in the inventor s eye An exception Technical developments falling costs anda combination of other circumstances
332. onal amp 3rd world interests Telecommunications policy Telecommunications Foreign control Government intervention industry j Standards Alternative medio ummdimeir amp e g cable DBS compatibility data network P networks Private networks Commercial networks V V Information providers of PTT or government policy instead of clashing with it Cur rent attitudes and actions in com munications deregulation parti cularly in the US and now in the UK obviously need close atten tion What should governments do and what will they actually do You may take the view that the less a government does the bet ter you may think it should have a limited role or you may think it should intervene at all levels I see little evidence that any gov ernment has had any success in intervening at the market level it may result in a disaster wit ness the rise and fall of Nexos In this area of rapid changes and new emerging markets bureaucratic involvement seems unhelpful All governments seem to be more or less involved with many of the areas shown on Fig 1 that is employment control of tele communications and privacy and security Involvement in communications because of the importance of what is communi cated particularly news spills over into topics like data protec tion the flow of information across borders and the concern of underveloped countries about this top
333. ood value save s Lucky dip service AVO multiminor test meter Tested 20 Ex eq p amp p paid AVO 7X Tested Ex eq 40 p amp p paid Opening times Monday Friday 8 30am 5 00pm Saturday 8 30am 12am Please allow 14 days for delivery MAINLAND ONLY A H THACKER amp SONS LTD HIGH STREET CHESLYN HAY NR WALSALL STAFFS CIRCLE 070 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com ESTABLISHEO 30 YEARS U K RETURN OF POST MAIL ORDER SERVICE ALSO WORLDWIDE EXPORT SERVICE RECORD DECKS 240 volt AC Post 2 FAMOUS LOUDSPEAKERS BAKER AMPLIFIERS BRITISH MADE A n MAKE MODEL SIZE WATTS OHMS PRICE POST Make Model Drive Cartridge Price AUDAX WoDtta SIZE WATTS OHMS PRICE POST PA150 Watt MICROPHONE VOCAL AMPLIFIER 129 BSR P170 Rim Ceramic 22 A 4 channel 8 I d 50K 600 oh 4 1 annel mixing inputs dual impedance ohm GARRARD 6200 R GOODMANS HIFAX TVs x 44 100 8 30 2 im Ceramic 24 i volume treble bass Presence controls on each channel Master GOODMANS HB WOOFER Bin 60 8 12 50 1 BSR P207 Rim Ceramic 20 WHARFEOALE WOOFER Bin 30 8 9 50 2 volume control echo send return socket Slave sockets Post 3 ESR pza H Magnetic pi CELESTION DISCO GROUP 10in 50 86 20 2 150 Watt MIXER AMPLIFIER 4 Inputs 99 200 Belt Magnetit 34 GOODMANS HPG GROUP 12in 120 815 2950 2 Discot
334. or and gear box 90 M M Max Dia 42 M M Shaft Length 15 M M ShaftDia6 M M Approx Half manufacturers price 15 00 p amp p 2 00 total inclusive of VAT 19 55 x HEAVY DUTY SOLENOID mf by Magne tic Devices 240V AC intermittent opera tion Approx 20tb pull at 125 in Ex amp equip Tested Price 750 p amp p t150 t 10 35 incl VATI R amp T fe 2 f v VORTEX BLOWER amp SUCTION UNIT Powerful mult stage dynamically balanced totally enclosed 9 cha Rotators 3 500 rpm 172 1D inlet and outer 110V AC Price 20 Suitable transformer for 2240V AC 5 t3 p amp p ttotalinc VAT 32 20 NMS E G COOLING or EXTRACTOR FAN Quiet smoothrunning Sue 4 4x4Jax1 2 Supphed tor 240V a c operation Price 4 75 o amp p total inc VAT 6 822 NMS 240V A C SOLENOID VALVE Designed for Air Gas at 0 7 Water 5ps Inlet outlet 38 Forged brass body Manut Oewraswitch Asco Price 550 1 p amp p 7 48 inc VATINMS um A E Ample parking space Showroom open Monday Friday TE VARIABLE VOLTAGE TRANSFORMERS INPUT 230 240V a c 50 60 OUTPUT 0 260V 200W 1A Max 15 00 OSKVA 21A Max 19 00 IKVA 5A Max 27 00 2KVA 10A Max 41 00 3KVA 15A Max 54 00 SKVA 25A Max 95 00 10KVA 50A Max 181 00 15KVA 75A Max 275 00 3 PHASE VARIABLE VOLTAGE TRANSFORMERS Dual input 200 240V or 380 415V Star connected 3KVA 5amp per phase max 113 40 All V V Ts amp KVA 10amp per phase max 170 10 plus 10KVA 16amp per phase max
335. ormation Technology said I am very pleased to see this project launched A trade union an enterprising British firm and an exciting new technology are working together ina way that should be a pattern for all The system will combine laser video discs with one or more microcomputers to produce a package of information 8 graphics According to the Managing Director of Epic Eric Parsloe The system will provide a low cost solution to a major industrial training and productivity problem and should certainly give the UK a lead in Europe Frank Chapple General Secretary of the Electrical Electronic Telecommunications and Plumbing Union commented The EETPU is the only union to have its own training facility for running courses in new technology Through this development the union has been able to offer a first class service that ensures that members are able to keep pace with developments in industrial technology and provide industry with the appropriate skills needed to install commission and maintain modern plant and machinery The joint development of the interactive videodisc learning system combines a training program on microelectronic technology with the very latest in teaching techniques and adds to the uniquenessoftheunions programmes supplemented with computer generated text and achievement The videodisc learning system will be able to illustrate difficult electronics concepts and
336. oscope or similar project This is complemented by a d to a converter with eight bit resolution 256 steps which incorporates a high impedance input buffer the interface module called Interbeeb includes a power pack for 59 95 while the AD pack and the DAC pack cost 19 95 each all prices inclusive DCP Microdevelopments Ltd 2 Station Close Lingwood Norwich NR13 4AX WW 222 to produce camera ready artwork It will also send output information to a photo plotter eliminating the camera stage Each Artworker station is a complete stand alone system with full design facilities Further workstations when added can share a plotter The basic price of the Artworker is 14 530 and this with a appropriate plotter is all that is needed for a complete in house p c b design system Wayne Kerr Datum Ltd Woolborough Lane Crawley RH10 2UG WW 221 WWW americanradiohistorv com MORSE RECEIVER FOR ZX81 A program for the ZX81 computer can translate Morse code signal received from a radio or other source and translate them into text which is displayed on the screen Two keys onthe computer are programmed to adjust the reading speed and when this is correct spaces appear between the words The cassette program is loaded and a loudspeaker feed from the receiver is connected by coaxial cable to the cassette input of the computer The instructions provide some useful hints and tips for the reception of signals includi
337. otons and rifle bullets in order to bring c into his argument about time and since it is the electrom agnetic theory that he is trying to save let us concede to him the light based definition of simulta niety that he proposes pro tem Einstein next puts a train onto his railway embankment travell ing in the direction A Bat veloc ity v and puts a second observer into the train Figure 2 so that just when the flashes of lightning occur as judged from the embankment this M in the train happens to be located exactly opposite M on the embankment half way between A and B If the observer M were not moving he would remain permanently at M and the light rays emitted by the flashes of lightning at A and B would reach him simultaneously i e they would meet just where he is situ ated Good But Einstein then goes on Now in reality considered with reference to the railway embankment M is hastening towards the beam of light coming from B whilst he is riding on ahead of the beam of light coming WWW americanradiohistorv com from A Hence the observer will see the beam of light emitted from B earlier than he will see that emitted from A Observers who take the railway train as their ref erence body must therefore come to the conclusion that the lightning flash B took place earlier than the lightning flash A We thus arrive at the important result Events which are simultane ous with r
338. over a phone line in two minutes Modern compact microprocessor controlled machine Price includes 200 sheets of TELEFAX paper and a cover for the machine 350 00 25 c p s DAISY WHEEL PRINTER Word Processing software 995 00 Please Note Available only from COMPUTER APPRECIATION 16 Walton Street Oxford 0X1 2HQ Oxford 0865 55163 AUTOTYPE 1 Church Street Cuckfield Haywards Heath W Sussex RH17 5JZ Haywards Heath 0444 414484 amp 454377 All prices are ex VAT amp carriage We have some ex demonstration machines available please enquire for details amp prices CIRCLE 052 FOR FURTHER DETAILS HIGH QUALITY REPLACEMENT CASSETTE HEADS a Do your tapes lack treble A warn head could be the problem Fitting one of our repiacement heads could restore performance to better than new Standard mountings make fitting easy and our TC1 Test Cassette helps you set the azimuth spot on We are the actual importers which means you get the benefit of lower prices for prime parts Compare us with other suppliers and seet LINSLEY HOOD 300 SERIES AMPLIFIERS THIS MONTH S SPECIAL OFFERS HIGH SPEED DIGITAL CASSETTE RECORDER A really super buy for the computer enthusiast These decks made by Burroughs use a capstanless cassette mechanism to record and replay data at 10 and 30 inches per second The read after write head uses an NRZ system with separate tracks for clock and dat
339. p 400 1 MAJOR 12 4 8 16 30 HI Ft 16 ranges DC volts 5 25 250 500 AC volts 10 50 500 9 0 9V 1 amp 3 50 1 20 40 60V_1 amp 3 50 2 SUPERB 12 8 16 30 HI FI 26 1000 DC amps 0 250uA 0 250mA Ohms 600K 10 0 10V 2amp 4 00 1 25 0 25V 2amp 5 50 1 WOOFER 12 8 80 HI FI 25 10 30 40V 2 amp 5 50 24V SampTwice 12 00 2 De Luxe Range Doubler MULTI METER dev 100ma 1 50 i 30V 2amp 5 00 1 AUDITORIUMA NS C Woofer 37 2i Mi A 19 50 12V 750 ma 2 50 1 30V 5ampana GROUP 45 12 4 8 16 45 PA 16 50 000 o p v 7x 5x 2in 50 eTO Ap AO o 12V 3 amp 4 50 1 17 0 17 2a 4 50 2 0G 75 12 48 16 75 PA 20 43 Ranges 1 000V AC DC 20 MEG 10 amp ost 12 0 12V 2 amp 4 50 1 35V 2amp 400 1 DG100 12 8 16 100 PA 26 LOW VOLTAGE ELECTROLYTICS DG 100 15 8 16 100 PA 35 PANEL METERS a acus na 500mF 12V 1p 25V 20p 50V 30p 1200mF 76V 80p REPAIR service to most Baker loudspeakers SPEAKER COVERING ma 50ma 100ma 500ma 1 amp 2 amp 5 amp 25 volt 1000mF 12V 20p 25V 35p 50V 50p 100V 1 20 Samples S A E CABINET WADDING 18in wide 35p ft VU2 1 AX2X11 4 Stereo VU31 4X1 5 8X tin 5 p p 50p 2000mF 30V 42p 40V 60p 100V 1 40 1500mF 100V 1 20 MOTOROLA PIEZO ELECTRIC HORN TWEETER GU K 2500mF 50V 70p 3000mF 50V 65p 4700mF 40V 1 in Square RCS SOUND TO LIGHT CONTROL BOX CAPACITORS WIRE END High Voltage 100 watts No crossover required 4 8 16 ohm 738 x 3 Ain 10 Complete ready to use wi
340. play Devices Dupiexers Electro Optical Devices Gas Relays Giow Modulators Ignitrons Image Intensifie rS Integrated Circuits Klystrons Klystron Amplifiers Microwave Tubes Microwave Semiconductors Photomultiplier Tubes Phototubes Planar Triodes RF Amplifiers RF Capacitors RF Resistors Terminations RF Transistors Readout Tubes Receiving Tubes Rectifiers Relays Spark Gap Tubes Tetrodes Thyratrons Transistors Transmitting Tubes Travelling Wave Tubes Triodes Tube Sockets Accessories Vacuum Capacitors Vacuum Interrupters Vacuum Relays Vibrators Vidicons Silicon Controlled Rectifiers X Ray Tubes ALSO AVAILABLE A replacement guide to dozens of Motorola Transistor part numbers Stocks of original RF Devices from such manufacturers as MOTOROLA RCA GE TRW MSC ACRIAN TOSHIBA FUJITSU NEC MITSUBUSHI PHILLIPS AMPEREX and others CHIMNEYS TERMS CREDIT POSTAGE VAT CONNECTORS CIRCLE 086 FOR FURTHER DETAILS WWW americanradiohistorv com POWER TUBE ACCESSORIES ENQUIRIES Quotation for any types not listed SA E Cash Postal Order of Cheque with order FINGER STOCK Accounts available subject to approved references Add 1 00 to order under 50 vaiue SOCKETS All prices are excluding VAT please add 15 to order and postage GUARANTEE All goods are to specification and sold with manufacturers warranty 19 Trackdown SWITCHMODE powe
341. priority devices that might need service are prevented from inter rupting more important tasks Note that condition four must be implemented as during an inter rupt service all devices capable of interrupting will want to watch what is being fetched from mem ory so that they can spot the return from interrupt op code being fetched and automatically re initialize themselves The dynamic memory control is quite novel For this reason and for the bad publicity that dynamic memory sometimes gets it is worth detailing a few WIRELESS WORLD MAY 1984 XS uty dc ANNA Olya OOl uA Oy eo AS ZOST9L AO AO d A diy L pa USIL AZ 3 o A b 6003 38l Xt 9d NL 301 26 98 Ast 097 SISIL S015 D6L AS 8l Ls 9L L X u sz ez oz d q Nd 08Z 9 0 NOBSEXH 90131 E amp lzlo to SSTA 013 4uaiDAmnbea Jo Q2 d 9UrJ SW HO 8 LU 3 0i 3j Dit jl yada uO m z baie lt ta Lg 9a Sa g Eg ca ta 0g a p TL a ajqissod sp jJous SO SP03 u4I 4914 YIDA 04 8s0 2 J A pa4unou aq pjnous 0S L ze pup ng A0 DE SJo D0dD asau jo au pepuauunoaa4 SI S1041IVdDI QQLWYOLNASZOE 9 J3 p E H puo n4 DJDUNW UOOL Bursn punoJ8 o4 Ajddns Ag ayy jo burjdnoosep jpJeqr BUN Po ILE PUD DLE D 4D u3iu 304 pasn si JI utu 4upjJodurun si 41 go 0g 304 suoij2euuo 09S oly g 6 OL H a EL 2Z pup Dz a ay SO pesn uayy pup SJJ 44513 ayy yo u na uo Jayjo YIDS 04 paj3auu
342. programs from those available commercially The course is intended for those teachers experienced enough to connect up a computer andruna fairly complex program The first OU pack on educational computers Awareness would bring a user up to this level The course requires some 40 to 50 hours study and is suitable for both primary and secondary school teaching The pack starts by showing how a small Logo program is constructed and how the user can modify its operation and make short procedure calls Educational programs are discussed including simulations models and information retrieval programs drill and practice adaptive programs and intelligent systems This leads to a critical analysis of three commercially published computer assisted learning packages so that the teacher can understand the qualities that make good software good Educational Software includes a study book activities book and course reader programs on disc and three commercial packages There is also an audio cassette Version of the course are available for Apple II which includes an offer for a generous discount on Apple Logo and for the RML 380Z which includes its own RML Logo versions for the RML 480Z the ZX Spectrum and the BBC model B computers are being prepared details from Micros in Schools Project Open University Milton Keynes RR ERR ERR e H t Walter Tusting Cocking Itis with mu
343. r at 6 55 MHz above the vision carrier phase modulated with a bit rate of about 700 kilobits second y i 0 See miS ee Ifthe system proves satisfactory in all types of terrain and does not cause interference problems with existing monophonic receivers the BBC hope to put it forward for European standardization though this may not prove easy in view of the current use in West Germany of an alternative analogue tv stereo system These days it is not enough to develop a good system to ensure winning a standards battle Along struggle Although political lobbying by the Services is usually conducted behind closed doors in 1978 Admiral Sir Edward Ashmore then a recently retired Chief of the Defence Staff in a lecture to the Royal Signal Institution made no secret of his vehement dislike of the command structure of NATO and the whole organisation of defence communications He advocated strongly that defence communications should be securely in the hands and control of the Services reversing the post war trend towards a part civil part Service system on the grounds that civilians might be provoked into industrial sabotage by hostile propaganda RN dislike of providing communications facilities for the civilian media was evident during the Falklands campaign while the influence of the Defence Staff on the Prime Minister was underlined at that time when she was persuaded by the th
344. r of Prestel sub scribers equipped with 1200 75 baud modems In this condition data to be sent is applied to the TD pin and the back channel received data appears on BRD instead of RD In a full RS232 interface the 25 pin connector has separate terminals for the main and back channels but for home compu ters which do not transmitted and received signals can be routed to the appropriate pins of the modem via switching logic governed by the setting of the mode switch The same switching must be applied to the handshake signals and RTS The computer sets the RTS request to send line to 12V to indicate that it is ready to receive data and in response the modem drives CTS clear to send to 12V to signify that the com puter may transmit These sig nals are inverted by the RS232 buffers and are presented to the Am7910 as and CTS or BRTS and BCTS in the case ofthe back channel Note that the RS232 line itself is governed by a negative logic convention and thus provides a good deal of scope for confusion To indicate that it is receiving a carrier from the telephone line the Am7910 takes to OV either its CD carrier detect pin or for the back channel its pin Again in a full RS232 interface these sig nals appear on the separate pins However in the Bell 202 mode transmission in the back channel consists simply of keying a 387Hz carrier on and off It follows that not all the modem s back channel signals are mean
345. r supply Barlec Richfield and have the solution L296 SWITCHING REGULATOR Available ex stock e Cost effective Short circuit protected Output over voltage e Switching frequency protection witenin s5 iv lo 40v output to200kHz Phone 0403 51881 4A output current e Very es eee Telex 877222 eta Up to 160w output Hab Mee power e Thermal shutdown B ARLE C e Programmable current 9 Remote yan and gt limiter Ef RICHFIELD gt e Soft start Control circuit for crowbar now better served to serve you better Reset output PR Precise 2 on chip reference Very few components For complementary evalu ation kit please write to Barlec Richfield on your company headed paper Barlec Richfield Ltd Foundry Lane Horsham West Sussex RH13 SPX A member of the IBR Electronics Group i CIRCLE 079 FOR FURTHER DETAILS IP WWD TRANSDUCER and RECORDER AMPLIFIERS and SYSTEMS RMN reliable high performance amp practical controls individually powered modules mains or dc option single cases and up to 17 modules in standard 19 crates small size low weight realistic prices 5 Nf LIO ES eao 49 51 Fylde Road Preston Laboratories PR12XQ Limited Telephone 0772 57560 CIRCLE 034 FOR FURTHER DETAILS IN VIEW OF THE EXTREMELY RAPID CHANGE TAKING PLACE IN THE ELECTRONICS INDUSTRY LARGE QUAN
346. radiohistorv com 68 Backplanes CLE 055 MIR FURTHER DETAILS THIS IS THE MAST TO SUPPORT YOUR OUTSIDE BROADCASTING New XT Series Masts from Clark Masts designed for vehicle mounting when headloads are heavy and Stability required is high This is the mast which meets all your requirements for an O B or E N G vehicle unit Tailored in every way for the job Clark Masts offer the latest state of the art in mast design with the background of more than 25 years of constant development and an unfailing availability of spares over the same period NEW SERIES vehicle mounted stability for very heavy headloads ta UK CLARK MASTS LTD EWW CLARK Binstead Isle of Wight England 4 Tel 0983 63691 Telex 86686 EUROPE GENK TEGHNICAL PRODUCTS N V EWW Woudstraat 21 3600 Genk Belgium Tel 011 38 08 31 Telex 39354 CIRCLE 024 FOR FURTHER DETAILS WWW americanradiohistorv com You need Control Data Acquisition Monitoring or Datalogging AND you need fast development If these are your reasons you need the Essex System Powerful NSC Tiny Basic FAST Software Development Low Cost Hardware Accurate Analogue Interfacing Eurocard System Full Documentation Proven Industrial Record Processor Card Basic interpreter up to 8K RAM 32K ROM RS232C 48 1 0 lines Eprom Programmer 12 Bit Analogue Card 16 channels A D plus 2 channels D A Opto Isolator Card 12 inputs 12 outputs at 3A 50V
347. ral law then it would seem that something very odd must have happened to Nature The Relativist would say that WWW americanracdiohistorv com Nature had always been that way but we never noticed Of course anything can hap pen in mathematics Arguing from the Lorentz transfor mations Einstein suggested that ordinary relative velocities don t add up 2 and 1 make 2 If we call the you to me velocity v and the light to me velocity c then he said the light to you velocity is not just the simple w ct v that you thought it was but the relativistic velocity ctv ctv Levid 7 Dev 7 One can scarcely refrain from murmuring q e d in response All that has been proved by this little excercise the so called Theorem of the addition of velo cities is that the steps from the assumed constancy of c to the Lorentz transformations and back again are free of mathemati cal error the result is just a re statement of the initial assump tion and the argument is entirely circular Whether or not it corre sponds to the working of the phy sical world has never been put to the test At this point I should put in the routine reminder that the velocity of light from a moving source a relatively moving source has never been measured What Michelson and Morley found was that if light was radiated from their light source at some veloc ity presumably c its velocity remained c when it was reflected i
348. rformance and may in the long term lead to damaged components Hunter Electronic Components Ltd Unit 3 Central Estate Maidenhead Berks SL6 7BN WW 210 WWW americanradiohistorv com WIRELESS WORLD MAY 1984 1000 s OF BARGAINS FOR CALLE HARD DISK DRIVES HOT LINE DATA BASE COMPUTER CAB wee Fuly refurbished DIABLO DRE series 30 2 5 Mb disk drives Allin one quality computer DEC RKO5 NOVA TEXAS compatible Front load Free stand or rack mount 550 00 Exchangeable type via lid removal 295 00 cabinet with integral switched mode PSU Mains filtering and twin fan cooling for the famous DEC PDP8 computer me3029 PSU unit for 2 drives 125 00 THE ORIGINAL FREE OF CHARGE dial up data base Originally made DIABLO DRE 44 4000A B 5 5 ex stock from 995 00 B 1000 s of stock items and one off bargains system costing thousands of pounds Made to run 24 Agog sick spares for S30 2090 3209 HAWK ex stock ON LINE NOW 300 baud full duplex CCITT tones 8 bit us in house reparr refurbishing service word no parity 01 679 1888 hours per day the PSU is fully screened and will deliver a Call for details or quotation EX STOCK INTEGRATED CIRCU MAINS FIL DC at 5 amps The complete unit is fully enclosed with removable top tid filtering trip switch Power and Run LEDs mounted on Ali front panel rear cable entries etc etc Units are in good but used condition
349. rially combined with the velocity of the machine to explain a phenomenon where the waves have a velocity that is independent of the machine velocity Perhaps in what I say here I am mistaken I would certainly like to see Professor Jennison s defence of his apparatus Chnis Parton Department of Electrical amp Electronic Engineering Bell College of Technology Hamilton Letters to the editor Letters for publication are always very welcome Many more come in than can be published since space in the journal is limited and I would therefore ask that letters be short and to the point so that heavy cutting need not be suffered Letters on new subjects will now be printed on the Feedforward page those referring to past topics already mentioned in articles or previous letters going in the Feedback section Ed 49 FEEDFORWARD Boost rai n Var ous pos amp ne a m csuppiy cols Fiywheel synt a e ANES A phase cet pulses Various gating juises puis f PAL switch tr gger H Ist il Line output 3 Scan curren ee ent for crt H Focus potential anace supply e transformer IRoster correction Convergence pu c centering Flyboce bicokim EA Eo pru s d Bp TELEVISION TECHNOLOGY I think it is time something was done about Television It has become rather nasty I am referring not to video vice and violence but to circuit technology The
350. rned by data stored in an internal rom and fre quency stability is assured by a quartz crystal Even the filterin is performed within the chip an so there are no setting up adjust ments to be made All the designer has to do is to interface the device to the telephone line and to the computer and of course to provide mode switching There are five control lines with which it is possible to set up any of nine normal operating configur ations For testing one line sets transmit and receive filters to the same frequency allowing data to be looped back through the modem The other modes are reserved by the manufacturer for diagnostic purposes Frequency assignments for the various standards are shown in Fig 1 The Bell 202 and CCITT V23 modes are described rather misleadingly as half duplex which means that the data rates in each direction are different Pres tel s 75 baud back channel can transmit data much faster than most people can type it but the equivalent in the Bell system offers a rate of only 5 bits per sec ond and its uses are therefore more limited To prevent conflict in the full duplex modes the modem originating the call should transmit on the lower pair of fre quencies and the answering modem on the higher The Am7910 has data and handshaking ports for a standard RS232 computer interface and CCITT V 21 channel assignments 300 baud 980 1180 1650 1850 1080 1750 fe fe FREQUE
351. rs are being given greater freedom to use Subsidiary Communications Authorization SCA facilities including the use of a second sub carrier The use of broadcast transmissions for area or nation wide radio paging based on the second SCA sub carrier is attracting increasing interest The first part of the ITU conference on h f broadcasting early this year in Geneva seems to have gone smoother than expected with even the Americans often critical of ITU conferences expressing satisfaction Frequency allocations requested by countries are to be computerized and a check is to be made to establish the extent of deliberate jamming However the conference was concerned only with establishing technical parameters and the main problems may come next time in 1986 615 delegates from 90 countries attended The Pentagon is planning to double its spending during 1985 on the protection of ground and airborne electronic command centres from the effects of e m p electromagnetic pulses generated by nuclear blasts Also planned is the establishment of a world wide network of five terrestrial electro optical surveillance centres to detect and identify objects in deep space for completion by 1988 48 COMMUNICATIONS COMMENTARY Amateur Radio Telephone and cable r f i The lack of attention paid to e m c problems by those supplying electronic equipment for homes cars petrol pumps etc is becoming ever mor
352. rsonnel Department at Company Head Office C W Cameron Ltd Communications Division Burnfield Road Glasgow G46 7TH Tel 041 633 0077 TO MANUFACTURERS WHOLESALERS AMP terminals type 152387 2 90 000 half price Automatic coil winder Blume and 450 Also BULK BUYERS ETC LARGE QUANTITIES OF RADIO TV AND ELECTRONIC COMPONENTS FOR DISPOSA SEMICONDUCTORS all types INTEGRATED CIRCUITS TRANSISTORS DIODES RECTIFIERS THYRISTORS etc RESISTORS C F M F W W etc CAPACITORS SILVER MICA POLYSTYRENE C280 C296 DISC CERA MICS PLATE CERAMICS etc ELECTROLYTIC CONDENSERS SPEAKERS CONNECTING WIRE CABLES SCREENED WIRE SCREWS NUTS CHOKES TRANSFOR MERS etc ALL AT KNOCKOUT PRICES Come and pay us a visit ALADDIN S CAVE TELEPHONE 445 0749 445 2713 R HENSON LTD 21 Lodge Lane North Finchley London N 12 5 minutes from Tallv Ho Corner 100 2764 EPROM 250NS 5 65 FD1771 FoC 17 50 75p P amp P VAT MICROSYSTEMS LTD 208 CROYDON RD LONDON SE207YX 01 6597131 2538 ENCAPSULATING EQUIPMENT FOR coils transformers components degassing silicone rubber resin epoxy Lost wax casting for brass bronze silver etc Impregnating coils transfor mers components Vacuum equipment low cost used and new Also for CRT regunning metallis ing Research amp Development Barratts Mayo Road Croydon CRO 2QP 01 684 9917 9678 WWW americanradiohistorv com equipme
353. rupts This is the Z80 s most complex mode of interrupt orga nization where in response to the Z80 acknowledging an interrupt by taking control lines M1 and IORQ low simultaneously the interrupting device supplies eight bits of an address This address combined with the contents of the Z80 T register forms a 16 bit pointer to a table of addresses of WWW americanradiohistorv com interrupt service routines Each device capable of interrupting is supplied with one or a range of such interrupt vectors during the computer s initialization so upon an interruption the Z80 is able to pick out and make a call to specific routines for each interrupting vector The strength of the sys tem though is that by changing the interrupt vector or a particular entry in the table of addresses different service routines can be provided for the same interrupt line This is particularly import ant for example with the disc controller used which uses one interrupt line to signal both a request for data from the system during disc writing and the offer of a data byte during disc reading This interrupt acknowledge sequence is condition seven in Table 2 On receipt of an interrupt the Z80 disables its interrupt sequence but pauses before acknowledging to allow what may actually be several interrupting devices to decide which has the highest priority This is done by the daisy chain technique men tioned earlier In this way lower
354. s 80 AM Electronics 84 Armon Electronics 10 Aspen Electronics Ltd 88 Audio Electronics ssseeeeeeeenne 22 23 Barrie Electronics LED ooo e ex eH REA 73 B Bamber 15324 Barlec Richfield Ltd 20 Beckenham Peripherals 10 Black Star Ltd 80 Binary Systems eere eee aho epe aeoo re toro nno 76 Cambridge Kits rone ier esent Pu Ee Oy Pte EVE TERES 92 Cambridge Micro Prossor s ng Carston Electronics 46 Clark Masts Ltd 68 Colomor Electronics sacla Computer Appreciation mE Control Universal i d Crimson Elektrik Stoke 80 Crotech Instruments 104 Cynpex Ltd a serisine rinners annsi estiS costae Dataman Designs Display Electronics Electronics Brokers 13 15 11 17 Electronic Equipment Co sees 84 Ellmax Electronics Ltd 2822 EMS Manufacturing 1 Essex Electronics eeeeeeeeeeeee nennen 68 Farnell Instruments Inside Front Cover Future Film Development eese 4 Fylde Electronics Lab 20 PAGE Global Specialities Corporation sese 5 GP Industrial Electronics Inside Back Cover Back Cover Grandata Ltd eee tre eoe eee enero 16 Greatech Electronics eee 19 Happy Memories iil oseeriedu Dia vae vaca x VF TE EXET UE 73 Harris Electronics
355. s military displays and ECM and ESM systems The Test Department is responsible for the test and Technicians Applicants should be educated to HNC HTC standard and have practical knowledge or experience of radar and or microwave systems Conditions of employment are excellent including a competitive salary five weeks holiday and company pension and life assurance scheme Interested Then phone me on 01 397 5281 or alternatively write with brief details of qualification experience and current salary to Mr P N Willis Senior Personnel Officer Racal Radar Defence Systems Ltd diagnostic functions on a wide range of complex radar Davis Road Chessington Surrey equipment using high quality manual and automatic test equipment Racals people are Racals success BRITISH ANTARCTIC SURVEY Electronics Technicians Applications are invited from suitably qualified and experienced persons to work as part of a team working on the design construction and main tenance of a wide range of electronic equipment The succesfull applicants must be able to build electronic circuits and systems which will be used for scientific research in the Antarctic at the Survey s Stations in remote field sites aboard their ships and in their aricraft They will be required to spend periods in Antarctica sometimes working from tents operating maintaining and installing electronic equipment resourcefulness and initiative are essential as much of th
356. s peripherals data acquisition systems micro processor controlled test instruments Trouble shooting and repair capability to component level experience with current model minis micros and GPIB a big advan tage Further details and application forms available from the Personnel Officer Brighton Polytechnic Mithras House Moulsecoomb Brighton BN2 4AT Tel 0273 693655 Ext 2536 Closing Date 4 May 1984 2560 Salary is competitive benefits include annual repatriation housing and transportation allow ances Candidates possessing the above requirements should only apply to the following address within one week of the release of this advertisement furnishing details resume of their educational qualifications and experience attaching copies of their degrees and transcripts giving names and addresses of four referees including their present employer if possible and the present position held LOGEX ELECTRONICS RECRUITMENT Mr Ali A Jaman Director General Financial and Admin Affairs Research Institute University of Petroleum and Minerals P O Box 7177 Dammam 31462 Saudi Arabia 2546 Specialists in Field amp Customer Engineering appoint j ments atl locations and disciplines Logex House Burleigh Stroud loucestershire GL5 2PW 0453 883264 amp 01 290 0267 24 hours WIRELESS WORLD MAY 1984 WWW americanradiohistorv com DISPLAYED APP
357. s has postulated the irradiation of two of the enclosure walls by a plane wavefront travelling horizontally and then generated a Huygens wavelet construction from those walls Mathematical ineptitude prevented a rigorous solution of the expressions arising but they did not in any case appear to contain the seeds of an explanation H C Wright Blisworth Northampton CODED TELEPHONE NUMBERS May I suggest a simple method of removing one of the most frustrating and error prone activities of any business This is the dialling of unfamiliar telephone numbers By means of a simple decoder attached to a standard telephone this would use trade directories visiting cards etc carrying their bar encoded telephone numbers The reader would be a simple wand with possibly a slot to allow cards to be passed through This system would of course only be of use if a significant number of the business sector used it Perhaps you would be good enough to raise the subject and help start by producing a suitable adaptor John Wilkins Somersham Cambridgeshire WIRELESS WORLD MAY 1984 SC84 microcomputer continued from page 40 The signal at the start of the Schmitt buffers is MREQ and not MEMDIS and not RF or ie unless H or ROMEN is active it is MREQ delayed by a couple of gates The starting falling edge of becomes a rising edge at the output of the first Schmitt gate This rising edge is slowed down by th
358. side Fig 1 Situation deduced by observer M Fig 2 Se E EET RT S Situation as seen by observer M Fig 3 References l Einstein A Zur Elektrodynamik bewegter K rper Ann d Phys vol 17 1905 pp 891 921 The quotation is from Lanczos The Einstein Decade Elek 1974 p 131 2 Einstein A Relativity The Special and the General Theory Methuen 1960 p 19 text dated 1916 3 Einstein A Op cit 2 p 148 appen dix dated 1952 4 Einstein A Op cit 2 pp 22 26 text dated 1916 All quotations which fol low are extracted in order from these five pages 5 Gamow G Mr Tompkins in Paperback Cambridge 1965 pp 13 14 6 Waldron R A Electric Forces Radio and Electronic Engineer Vol 51 1981 pp 553 560 72 MODERN PHYSICS I will paraphrase that result because of its importance If the velocity of light were independent of the velocity of its source as claimed then as seen by two observers M and M in uniform relative motion the flashes which originated at points A and B when M and M were spatially coinci dent at the mid point of AB must arrive at the future positions of M and M simultaneously It would then follow that the times kept by observers M and M must be identical in an absolute sense That is the exact opposite of the conclusion which was reached by Einstein in this his own scen ario Unbelievable you will say
359. sition would interest you please send a CV and any additional information you feel relevant to maxell Maxell UK Lid 4 Tyburn Lane Harrow Middx HA 3AF 2542 Senior Technical Assistant from 9 300 p a The Purchasing and Supply Department of the Independent Broadcasting Authority based at Harrow now hasan opportunity for a Senior Technical Assistant to lead its small Technical Services Group Provision of technical services includes goods inwards inspection storage environment component testing repairs to electrical equipment and maintenance of office equipment held at Harrow Candidates require a good secondary education to O level standard and TEC or City and Guilds in Electrical Electronic Engineering or equivalent knowledge and experience at a similar level Considerable experience in a technical stores environment of a large organisation dealing with a wide range of complex technical equipment will not only have furthered technical knowledge of electronic components and equipment but brought an appreciation of stock control purchasing systems and procedures and of computer usage in stores and stock control Anexcellent working environment and conditions of employment are offered IBA For further details of the vacancy and an application form please telephone 01 584 7011 ext 390 9am to 5pm weekdays INDEPENDENT BROADCASTING AUTHORITY An Equal Opportunities Employer 2545
360. st be defined by the transmission of information to some observer by means of light signals is solely that such a definition if accepted permits an independent deriva tion of the Lorentz transfor mations If that definition 1s rejected many persistent physi cal and conceptual difficulties are immediately concentrated into the area where they properly belong where also once ident ified they can be dealt with Up to and including the third quotation above 1905 1952 it is clear that Einstein s first intention had been to modiy electromag netic theory in such a way as to bring its erroneous predictions into line with the rest of physics rather than vice versa the classi cal mechanics of Galileo and Newton conforms with the rela tivity principle As an intention it was wholly admirable but alas things did not work out as intended The only compromise acceptable in the atmosphere of 1905 seemed to be one which left the already disproved but sacro sanct electromagnetic theory untouched but insisted instead that the simple natural world of energy and motion time and space must become distorted in order to accommodate its failure The irrationality of that develop ment was breathtaking and the precedent it set was unfortunate natural philosophers have had to ut up with a lot of nonsense for a ong time Suppose we were to return to Einstein s original inten tion and try to put an end to the nonsense by corre
361. stal and oscillator so the crystal used on the processor board will not affect i o data rates etc with the proviso that the processor clock must not fall below 3 6MHz if 3 5 or 8in dou ble density disc drives are used When the RESET pin on the Z80 is active everything including memory refresh stops For this reason the reset monostable i c generates a short pulse and no matter how long the reset button is held in refresh is only briefly interrupted so that no memory corruption occurs As well as pro viding a reset signal for the Z80 and all peripheral circuits the pulse is used to set a bistable i c WIRELESS WORLD MAY 1984 formed from two gates of IC The output of this bistable device gates ith A to produce a signal which follows A while the bistable i c is set and enables rom whenever A is low i e during access at any add ress from zero to 7FFF On receiving a reset signal the Z80 starts to fetch and execute instruc tions from address location zero This means that following reset the Z80 executes instructions from eprom At the base of the eprom it finds instructions to E a part of the rom at the top 8K bytes of system memory fol lowed by a jump that area This copied software is the machine code operating system whose first instruction is an i o read which mue to the IORQ line going active during its execution resets the flip flop and forces ROMEN to the inactive high state disabl ing the
362. system with say Basic in rom will be ready to program in Basic as soon as it is switched on that rom is an encumbrance when you want to use anything else but Basic The classic argument against disc based systems is that a rom based system is ready for use as soon as you switch it on whereas initiating a disc based system can take as much as 45 seconds SC84 initiates in just under one second and leaves vir tually all of the system ram avail able for whatever you want Basic Pascal machine code assembly word processing etc A major feature of SC84 is that a disc operating system SciDOS has been written especially for it As well as implementing those commands and functions neces sary for CP M compatibility this software provides some extra commands and functions which make the system of use to those who see a computer as more than a black box SciDOS has been kept small by efficient programm ing when it is loaded and runn ing up to 58K bytes of memory are free for user programs SC84 is built on 100 by 160mm Eurocard p c bs interconnected through a 64 way bus system The basic configuration consists of a processor card a character v d u card and an i o card Frames for housing Eurocards are available in various sizes and materials the interconnecting bus or backplane being either a p c b again readily available or a series of card sockets linked using wire wrapping tech niques Prototypes h
363. t at rest Yet the observed pheno mena are exactly the same in both cases That last sentence again embod ies the principle of relativity but it is the first sentence in the quo tation that provides the vital key Maxwell s electromagnetic theory violates that principle But there was and still is no doubt about the sheer power of the electrom agnetic dogma among its adher ents Faced with this crisis the theory s protagonists held on adamantly to their all dominating Faith Asl said in this connection in the third Heretic s Guide article WW October 1982 page 77 Human feelings at levels deeper than mere reason were involved in this conflict Thus Einstein again almost plaintively the square brackets are my own sym pathetic additions Prominent theoretical physicists were therefore more inclined to reject the principle of relativity than the e m theory despite the fact that no empirical data had been found which contradicted that principle and even though experimental data had contra dicted e m theory WWW americanradiohistorv com dace by W A Scott Murray B Sc Ph D 69 By writing down a group of mathematical equations the Lorentz transformations H A Lorentz was able to compensate for the failure of Maxwell s electromagnetic theory to cope with relative motions In 1905 Einstein derived these same equations by postulating without evidence that the ve
364. t if K AK19 e wiring The Kit comprises a LL transmitter with pre drilled box and two receivers XK112 42 00 Designed in accordance with CP3 Chapter V part 2 1972 for a minimum wind speed of 140 kph in conditions of maximum exposure and specified by professionals world wide where hostile environments demand the ultimate in design quality and reliability Suitable for mounting equipment in the fields of Communications Security surveillance CCTV Meteorology Environmental monitoring Geographical survey Defence range finding Marine and aero navigation Floodlighting Airport approach lighting Further details available on Pee p DA fags SR STRUMECH ENGINEERING LIMITED Portland House Coppice Side Brownhills Walsall West Midlands WS8 7EX England Telephone Brownhills 05433 4321 Telex 335243 SEL G M2 1 Receiver Kit XxK111 MK12 state latched or i addi momentary 13 50 E d i t MKS 4 way Transmitter Lone Keyboard 1 90 receivers o MK10 16 ba 10 x Keyboard 5 40 MK15 Dual Latched Solid si Relay 4 50 MICROPROCESSOR XK 114 CONTROLLED OPTIONAL MULTI RMERESE TIMER RELAY KIT lighting hi fi system and lots more 3 90 ur selection itis designed to contro g on and off at pre set times ove Kit includes one relay PCB t accommodate up to four nt switching times relays termina blocks etc 1o your system 10 fit inside CT6000 box eke Jsi Pe clack wil se andor 39 00 240V changeov
365. t Set Type TF 1267 40 Rhode amp Schwarz Group Delay Measuring Equipment ndicator 50 Rank Telecoms Battery Charges 10 Marconi Variable Attenuator 7 5ohm Type TF 1073A 2S 20 Marconi AM Signal Generator 10 500Mhz Type Pye pocketphone PFI Battery Chargers 12 Way 10 60 ampAllernator amp Generator Noise Filter 1 00 each TF801B 125 ITTSlarphone Battery Chargers 10 Instrument Fans 4 1 2 x 41 27 240vac f 3each 110vac 1 50 each Marconi AM Signal Generator 10 310Mhz Type Tektronix Hard Copy Unit Type 4601 125 Garrard Car Cassette Player Mechanisms Stereo Head 2 50 TF801A 1 85 Advance Pulse Generator Type PG 5002 85 Tektronix Oscilloscope Probes 10 each Marconi Standard Signal Generator 15Khz 440Mhz Siemens Milliwattmeter 50onm 500mW 0 12 4Ghz 95 Pye Pocketphone Rx Ni Cad Balleries 3for 100 Type TF867 85 Gaumont Kalee Flutter Meter 40 Mullard Vari cap TV Tuners Type ELC 2003 Ex Brand New Sets 3 50 Marconi RC Oscillator 20Hz 200Khz Type TF 1101 85 Siemens Transistor Power Unit0 30v 2amp 30 Pye Cambridge Vanguard 18 Way Control Leads 4 00 Marconi AM FM Signal Generator Type TF 995A 5 230 Avo Valve Characteristic Meter lype3 40 Sony1 2 Video Tape 5 Reels 2 00 Marconi VHF Signal Generator Type 1F 10648 5M 125 AirmecWave Analyser lype 85330Khz 20Mhz 45 BNCPlugs750ohm 50p each Marconi Tx amp Rx Output Test Set Type TF 1065 85 Sullivan RC Oscillator 40Hz 125Khz 35 IC Test Clips 28 pin amp 40 pin
366. t very few people have heard of this counter argument which was not invented by me nor even realised that the paradox existed Those who wrote the textbooks did not want to know Isuspect that most people will hold the same view about the present result as they do already about the other better known aradoxes of relativity theory e established method of deal ing with challenges to the logic of Special Relativity is to ignore them and why not For by usin relativistic mechanics specif ically mass increase in the inter pretation of physical measure ments one can always bring one s experimental results into line with the predictions of electrom agnetic theory which is all that a scientific technician need be con cerned to do A natural philoso pher on the other hand will go on trying in the hope that he may WWW americanracdiohistorv com in the end arrive at a logically con sistent paradox free under standing of the physical universe There are limits intellectually beyond which people of this sec ond kind cannot be pushed It would be more in accord with the notional methods of sci ence to make use of such anoma lies rather than deny their exist ence The lesson to be learned from this one is that we mere humans are not entitled to define the fundamental physical opera tor TIME in an ad hoc way simply in order to save any particular theory The reason behind the demand that time mu
367. tc Ref DOCE 140 STANDARDISATION ENGINEER Circa 19500 22 500 net Will determine specifications etc and technical acceptability of substitutions Must have in depth knowledge of communications materials equipment and spare parts 8 years experience is required in design research maintenance or a related area Ref STE 141 ARAMCO AT SENIOR COMMUNICATIONS TECHNICIANS 6 posts Circa 15 17000 Will carry out the maintenance and repair of a variety of communications and electronic equipment including UHF VHF radio systems and radio data systems One post will include the monitoring of the quality of the technical and administrative performance of contractors plus cost verifications for statistical purposes Candidates should have a minimum of 10 years post apprenticeship experience in the maintenance and repair of communications and electronic equipment Ref COMT 142 For the Engineering posts a relevant degree HNC or equivalent is required and for the Technician posts an apprenticeship plus the experience specified above These single status appointments offer open ended contracts with the usual tax advantages The excellent range of benefits include low rental accommodation fully furnished and air conditioned regular UK leave with company paid air fares free medical care and good sports and recreational facilities Please write with full career details quoting relevant ref no to Webb Whitley
368. th cabinet size 9x 3x5in 2 001 002 003 005 01 02 03 05 mfd 400V 10p HORN BOXES complete 200 watt 30 300 watt 35 Size 3 channel 1000 watt each For home hi fi or disco 7 M EDU MAD apse 1000X 235p TA 16x6x6in Black vinyl covered with handle Post f4 j Post 1 50V 12p 6l 1 175 E OR KIT OF PARTS 19 50 os AIME 1S0V 10 100V 280 630V 309p CROSSOVERS TWO WAY 3000 c s 30 watt 3 60W 3 50 100W 4 BATTERY ELIMINATOR Mains to 9 volt D C 400MA HIGH VOLTAGE ELECTROLYTICS THREE WAY 350 cps 3000 cps 40 watt rating 4 60 watt 6 100W 8 Stabilised safety cutout 5x 34x 2Voin 5 Post 1 2 500V 45p 32 32 16 350V 90p 8 16 450V 75p LOUDSPEAKER BARGAINS Please enquire many others in stock 16 450V 45p 100 100 275V 50p 16 16 350V 80p 4 ohm Sin 7 x 4in 2 50 6 4in 8 x 5in 3 8in 3 50 62r 20W 7 50 DISCO GRAPHIC MIXER EQUALISER 108 Post 2 20 500V 75p 150 200 275V 50p 32 32 350V 85p 8 ohm 2n 3in 2 5 x 3n 6x 4in 7 x 4in 5in 2 50 3in 10W 4 4 channel stereo 5 band graphic red green LED VU 32 350V 32 32 32 450V 95p 16 16 450V 1 8 Sin 3 Bin 4 50 10in 5 12in 6 Bin 25W 6 50 60W 12 50 display headphone monitor 32 500V 956p 50 50 50 350V ap 50 50 300V 50p 15 ohm 2Vun 3 2in 5x 3in 6 x 4in 2 50 6 in 10W 5 Bin 4 10in 7 Deluxe Model 5 channel 7 band graphic 118 125 500V E 8 8 500V 50 50 350V 80p 25 ohm 3in 2 5x3in 6 4in 7 x 4i
369. the standard 67401 The memory is organised as a 64K by 4 bit structure and may be cascasded to any width or depth Typical applications for these first in first out memories are for print spoolers disccontrollers communications buffers modems etc Monolithic Memories Lynwood House 1 Camp Road Farnborough Hants GU14 6EN WW 206 82 the substrate which also includes decoupling capacitors Mounted NEW PRODUCTS o Built around the c mos version of the 6502 a controller module may be programmed using a BBC computer Programs are generated in assembly language on the BBC and then downloaded into the control board where it may be stepped through or run When development is complete the program can be entered on an eprom for normal operation As c mos is used throughout the controller may be battery powered Applications include robotics machine controllers MICRO CONTROLLER data loggers automatic test equipment and any device requiring intelligent control The board may be purchased built and tested 84 98 or asa bare board The monitor eprom may also be purchased separately and the technical manual supplied with the assembled circuit can be bought for 2 50 Nikam Electronics Ltd 25 Suffolk Drive Lacey Green Wilmslow cheshire SK9 4DE WW 207 MEMORY IN BULK High density memory arrays can be provided simply and at lower cost by combining several 64K rami
370. the characteristic impedance of post modifier modulator filter used in Fig 34 March R is 759 Calculated values R 106 072 R 106 07 2Power loss 7 66dB Forward voltage loss 10 67dB Reverse voltage loss 4 65dB Insertion loss 7 14dB 6 to12V Measuring set 6 to12V This circuit avoids the high losses of matching pads 812 resistor may be removed to reduce insertion loss With the above circuit placed close to the generator the output waveform was unaffected but check with oscilloscope 820 to 1 8k to suit delay line For 1509 filter make left two resistors 1062 1502 on right For 5109 filter make left 4719 right 5100 decoder pin using the colour bar test signal f The diagonal to vertical chroma transition will also have an upward moving Hanover bar dis turbance visible at each colour change in a manner similar to the black and white photograph of Fig 48 Also the modified per formance will certainly be marred by cross luminance returning to the luminance channel giving subcarrier dot crawl at vertical transitions as shown in Figs 49 and 50 Figure 51 shows the1 t s performance for this transmitter Given such transmitter perform ance it is necessary to know the condition of the received signal before deciding whether to add the extra board and or improve thei f strip or the alternative fil ter circuits to be described next Where the incoming signal is received from a chain of transmit
371. they are indistinguishable assuming that the receiver has a sufficiently high bandwidth Thus the two input pulses in Fig 5 a will still be detectable separ ately if they emerge as in b but 2 if they overlap to the extent of c Ina multimode fibre the band width is primarily determined by two mechanisms modal delay spread and material dispersion coupled to the source spectral bandwidth As the amount of pulse spreading depends on the length ofthe fibre it is most useful to quote the performance of a fibre as the product of its band width and length For any given fibre and source bandwidth can be traded off against length how ever the maximum length may be restricted by the allowable sys tem attenuation see part 3 Modal delay spread The first of these bandwidth limiting factors modal delay spread refers to the differences in the group delays of different waveguide modes In terms of ray optics this is equivalent to saying that the rays which are totally internally reflected at the higher angles of incidence on the core cladding boundary take a longer zig zag path before emerging at the far end of the fibre Referring back to Fig 3 shows that a ray tra velling at an angle relative to the fibre axis takes l cos 6 im longer to travel an axial distance than does a ray travelling straight along the axis The maximum time delay difference will be 9T A n c ns km where c is the speed of light in
372. thout accessories 175 00 2701 Step Attenuator 50N O 79dB in 1dB steps DC to 2GHz 295 00 795 00 775 00 750 00 WE NOW STOCK A RANGE OF HEWLETT PACKARD COMPUTERS AND CALCULATORS Trading Conditions Available on request Electronic Brokers Ltd 61 65 Kings Cross Road London WCTX 9LN Tel 01 278 3461 Telex 298694 poem ee ee oe INDUSTRY STANDARD Modem Filters New Low Prices in OEM Quantities From Stock SELF FEED SOLDER GUN Eliminates need for a third hand ontricky jobs feeds a controlled length of Solder to the joint at the squeeze of the trigger Solder may be fed from standard reels or loaded onto gun mounted holder Two models 40w and 60w 240v Light Soldering Developments Ltd 97 99 Gloucester Road Croydon CRO 2DN 01 689 0574 CIRCLE 044 FOR FURTHER DETAILS aan aos acy70 0160 auni 1400 Teasz0 0750 2N 37710550 JAPANESE ecces 0420 ien AAMS D BCv7 0160 BUI26 0700 Basso 0750 2837 20900 TRANSISTORS PC8O 8580 itD imm AAY32 BCv72 0160 BU204 0 750 TBASGO 0700 2N 37731000 25473 0300 PLF200 1350 REO goose AC 107 BD t 0280 Bu205 0700 TBAgD0 0350 2N 40310260 25210 0320 PCFBOI 1100 ACI26 BO124P 0500 BU208 0750 tBasioso6oo 2N 10360250 2Saisa 0220 PCr802 D570 LED Imm AC BO124 1100 BU208A 0800 TBAB20 0 750 2N 40370250 2542010300 PCr amp 06 1150 tttOw Q100 ACU B 050 B0128 8UPO80 1200 TBAS20 0 300 2N 44430760 zsaa
373. tments is to make certain we deliver vour monitor by courier within ten days of receiving your order You can order by filling in the coupon below and posting to Opus Supplies Ltd 158 Camberwell Road London SES OEE Or by telephoning 01 701 8668 quoting your credit card number Or of course you can buy at our showroom between 9 00 6 00pm Monday Friday 9 00 1 30pm Saturday To Opus Supplies Ltd 158 Camberwell Road London SES OEE Please send me High Resolution Colour Monitor s at 4229 95 each ex VAT Medium Resolution Colour Monitor s at 4179 95 each ex VAT Connection leadis at amp 06 00 each understand carriage per monitor will cost an extra amp 00 N B A High Resolution Monitor including VAT leac and carriage costs 279 39 A Medium Resolution Monitor including VAT lead and carriage costs amp 221 89 Tencloseacheque for amp ___Orr please debit mv credit card account with the amount of My Access Barclaycard please tick no is Please state the make of your computer CIRCLE 037 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 Name Address Opus Telephone Opus Supplies Ltd TENTE wen 75 ER X INE Dach T ee WWW americanradiohistorv com prof ee ee 76 SUPER HY LIGHT STROBE KIT Designed for Disco Theatrical uses etc Approx 16 joules Adjustable speed Price 45 2 p amp p Total inc VAT 54 05 Case and reflector pr
374. tor 35 Compressor 39 Standard Reference Inductors 7 50 ea Variac 20 A 49 2KW 340 110 transformer three outlets 39 Rank wow flutter meter 75 Polaroid back 15 Grunther CRI servicing testing and re activating Unit 40 20A variable resis tance 20 metal case Mullard H S valve tester Avo valve characteristic meter 040 376236 2016 102 ter controlled for automatic electrical inspection of PCB s Offers invited Phone 01 223 2102 ext 211 Mr D I Fenton Lewis 254 SETTING UP A RADIO STATION Professional quality VHF FM broadcast transmitters and repeater links available 28 250 watts all solid state continuously rated Mono Stereo versions High sta bility PLL Xtal references Competit ively priced ie 100 watt model with inte gral mains power supply 280 Fully guaranteed Cyberscan International 3 Eastcote View Pinner Middx HAS 1AT Tel 01 866 3300 2551 COMPONENT SCOOP PURCHASE ONE MILLION C280 MULLARD PHILIPS POLYESTER CA PACITORS Ideal for the trade or manufacturing 001 to 047 mfd 100v wkg Assorted values 10 per 1 000 lot pp 1 000 of one value 1250 p p 1 5 000 assorted 42 pp 2 Please add VAT MAINS TRANSFORMERS Famous manufacturer TYPE Midget clamped type Input 200 250v 250 c s Output 250 0 250 60 m a 63v at 2 amps 250 each pp 150 Ten transformers 17 50 carnage 4 TYPE 2 Mains input Output 35V at 1 4 amp Price 2 25 each
375. tortaca tor direct connection uiti CRT 45 00 or Green CRT 55 00 miniature reversible fan Uses a brushless ZA ORIC ddn bee ace y nob DIU Carr amp Ins 5 00 servo motor for extremely high air flow PUGH pe Nel eed eae ala SA ED 12 CASED Made by the British KGM Co almost silent running and guaranteed 10 000 uS Ni MODE for WORD PROCESSOR applications 80 132 Designed for continuous use as a data l display station unit is totally housed in an hr life Measures only 62 x 62 x 22 mm lumns single sheet ket HH handl j Current cost 32 00 OUR PRICE ONLY imma much more Available ONLY from DISPLAY ELECTRONICS ff attractive brushed aluminium case with ON 12 95 complete with data at the ridiculous price of ONLY 199 00 VAT Complete with B OFF BRIGHTNESS and CONTRAST UENCE AUR Standard d ES full manual etc Limited quantity Hurry while stocks last JJ controis mounted to one side Much C625 OP M AA 95 or BRAND NEW ADS i Options Interface cable specit for BBC ORIC attention was given to construction and at 1050 1000 s of other fans Ex Stock DRAGON or CENTRONICS 36 way plg 12 50 Spare ribbon M reliability of this unit with features such as Call for Details Post Packing on all fans 1 69 3 00 each BBC graphics screen dump utility program 8 50 internal transformer isolated regulated DC supply all components mounted on two Carriage and Ins 10 00 VAT IY PCB h J f EPROM COPIERS GE TERMIPRINTER
376. torv com 81 PEAK ENVELOPE POWER MEASURED FOR HAMS A module is produced which can be added to a forward power meter to convert it to read peak envelope The common s w r meter or the in line wattmeter can often give misleading readings when used with s s b transmission According to Amateur Accessories the natural tendency of the operator is to increase the microphone gain or speak too close to the microphone in order to get some response from the meter It is exactly these circumstances that the peak envelope reading is so valuable as it enables the user to operate within the correct parameters for the output stage The module consists of a p c b with one integrated circuit and a number of discrete components It has been adjusted for zero readings and then sealed It comes with mounting hardware and may be fitted to an s w r meter oran a t u and needs no particular knowledge or skills to fit When fitted the circuit is adjusted so that the meter gives the same reading as it did before fitting and the meter will behave exactly as before when used with continuous carrier modes 12 from Amateur Accessories Ltd Church Street Glan Conwy Colwyn Bay Clwyd LL28 5LS WW 205 FAST F I F 0 For those seeking the speed of t t l inspooler memories without the power consumption they could look to the 67L401 from Monolithic Memories The device has a maximum I of 110mA about 30 lower than
377. tow adequate CIF Details available most modets send SAE 01 402 6822 ORDER BY POST OR PHONE CIRCLE 041 FOR FURTHER DETAILS WWW americanracdiohistorv com WIRELESS WORLD MAY 1984 DIGITAL MULTIMETERS UK C P amp ins Bench type 1 00 Hand held 65p PROFESSIONAL SERIES Thandar Bench Portables TM355 3 digit LEO 29 ranges 10A AC DC 20 Mag ohm 0 25 basic TM356 35 DE LOO 27 ranges 10A AC DC 20 Meg ohm 0 25 basic TM351 414 digit LCD 28 ranges 10A AC DC 20 Mag ohm 0 1 basic 115 00 Optional carry case 5 95 Thuriby Bench Portables Optional carry cass 18 00 1503 4 digit LCO 0 05 basic 104A resolution plus frequency measurement up to 4MHZ AC DC 10 Amps 159 00 1503Ha 45 digit LCD as above but 0 03 basic 175 00 1054 4 digit LCD True AMS version 185 00 1905a 5 digit Intelligent multimeter IUA resolution 0 015 basic 325 00 METRIX HAND BENCH PORTABLES ITT Size 188 x 86 x 50mm Rotary controls MX522 314 digit LCO 21 ranges 10A AC OC 2 Mag ohm Basic 0 5 67 00 MX552 314 digit LCO 29 ranges 10A AC OC 20 Mag ohm Basic 0 2 Plus continuity tester 95 00 MX563 True RMS 3 digk 30 ranges 10A AC 0C 20 Mag ohm 20HZ to SOKHZ 0 1 basic 155 00 MX575 41 digit True AMS 21 ranges 10A AC OC up to SOKHZ 2 005 basic 175 00 HAND HELO MODELS Controls S Silde R Rotary PB Push button All feature AC OC volts DC amps many with AC amps ohms etc UK
378. ts full battery backup possibilities include an Electronic Diary automatic document dating precise timing and control in riage scientific applications recreational use in games FX80 Tractor Attachment 37 1 50 car etc its uses are endless and are simply limited by riage one s imagination Simply plugs into the user port Paper Fantold 2000 sheets 13 50 2 50 no specialist installation required No ROMS carriage Supplied with extensive applications software 29 BBC EPROM PROGRAMMER A fully self contained Eprom Programmer with its own power supply able to program 2516 2716 32 32A 64 128 single rail Eproms Personality selection is simplified by a single rotary switch Programming voltage selector switch is provided with a safe position Warning indicator to show programming in progress Programmer can read blank check program and verify at any address addresses on the EPROM Simple menu driven software supplied on cassette transferable to disc Full editor with ASCII disassembler Assembly Lang Prog for BBC peeo emmen complete with cables software and operating instructions 89 2 p amp p PRODUCTION PROGRAMMER P8000 P8000 provides reliable gang programming of up to 8 EPROMS simultaneously with device sizes up to 16k x 8 bytes Devices supported range from 2704 to 27128 in single and three rail ver sions Simple menu driven operation ensures easy eprom selection and relia
379. ttube base and stray 12pF can discharge through the transistor On posi tive edges the rise time is deter mined by the load resistor a c feedback cannot help To obtain a reasonable performance low valued resistors have to be used resulting in high dissipation 10 20 watts A better solution is to use some form of push pull circuit with complementary transistors or active pull up by means of an emitter follower Advantages of newer types of output stage are better symmet rical bandwidth lower dissipa tion similar rise fall times and larger output amplitude A com plementary circuit is shown in Fig 40 taken from a note issued by the Mullard Applications Laboratory Mitcham In this cir cuit both the upper BF423 and the lower BF422 transistors are biased to conduct sufficiently to maintain correct d c conditions at picture back level and the capacitor 4 7nF and 2 2pF enable the transistors to provide peak currents on voltage tran sients of several times the means This will give rise fall times of 100ns with a full ampli tude response flat to 4MHz falling to 3dB down at about 5 6MHz and providing up to 40V pk pk output to 9MHz It will also han dle the tube cathode input imped ance of down to 9kQ without WIRELESS WORLD MAY 1984 introducing non linearity The colour tube current can peak to 7 5mA on peak white and at black level the input impedance reaches maximum capacitance Dissipa tion
380. tuent signals The monostable i c sets the minimum active RA period and thus by definition the minimum inactive Once the leading edge of the RAS pulse has latched the first address byte into the memory 1 cs theaddressmay be changed to that of the bus row to be fed to the output of the memory The eight bits are gated in by the start ing edge of the column address strobe CAS signal and com bined with the stored bit from the previous addressing strobe to operate a 1 out of 512 data mul tiplexer which selects and latches the signal from one of the 512 bus lines within the memory Once this is done may go inac tive indeed it is a good thing if it does as then the sense amplifiers may return to a balanced state as soon as possible ready for the next access CAS also controls the state of the memory output driver While it is active the out put is enabled and the selected data bit held there CAS is a far less sensitive signal as far as integrity of the memory is con cerned the main consideration being that it becomes active as Soon as possible in the access and stays on until the data is definitely available and the Z80 has it WWW americanradiohistorv com This has been a description of a memory read cycle write cycle is similar in that the signal connects cells to buses and releases sense amplifiers and then the CAS signal operates the latching multiplexer and activates the output driver What is diff
381. tulas abrasive sticks tweezers clamps and knives The de luxe kit has all that and an temperature controlled soldering iron and five pairs of pliers All items can also be purchased separately OK Industries UK Ltd Dutton Lane Eastleigh Hants SO5 4AA WW 220 P C B C A D Finding p c b layout laborious and existing computer aided design systems too expensive Keith Ingham a hardware and software engineer designed his own c a d system entirely in machine code This makes the system Artwork plus very fast and Mr Ingham has managed to incorporate a number of very useful functions curved tracks for example and a facility for dumping work in progress to a dot matrix printer At its simplest level Artworker is a computerized analogue of a drawing board with 18 overlay sheets in register and the drafting pen replaced by a cursor A p c b designer with no computer experience could use the system with very little difficulty claims Ingham The system compiles a list of allinterconnections as the work progresses and if a component is repositioned then the connecting tracks are reoriented to suit library of the user s company standards may be kept on disc and the redrafting of a standard board is reduced to a ul onm WIRELESS WORLD MAY 1984 minimum Library space can also begiven to a host of standard and non standard pad layouts Pads can be placed to an accuracy of 0 01mm and tracks to 0 6mm
382. ture NA defined as sin int ma In this example NA 0 1 It is a feature of optical fibres that they require a light source with a narrow emitting angle to efficiently couple power into the fibre Two requirements conflict when deciding on a suitable value of A and hence NA for a fibre A large stepindex makes it easier to couple powerinto the fibre but the increased total internal reflection angle allows a greater number of zig zag paths per unit length The increased length for some rays tend to smear out fast data pulses and reduces the potential band width available On the other hand a low value of A produces a higher bandwidth fibre but makes it more difficult to couple energy into the fibre The two major fibre character istics of interest from a commu Jacket Cladding Fig 1 An optical fibre consists simply of an inner flexible rod of very pure glass surrounded by a cladding layer of slightly lower refractive index by Brett Wilson STEP MULTIMODE b Typically 50 100um Qc GRADEO n MULTIMODE c Typically 5 10yum lel Me n Fig 2 Choice of refractive index profile determines the propagation characteristics of the fibre STEP MONOMODE Fig 3 Light in the fibre is guided by a process of multiple internal reflection caused by the difference in refractive index between the core and the cladding For a typical step index multimode fibre Dc 1
383. types This simple modified Pierce circuit works with crystals from 25k to 19 MHz Oscillation frequnecy is the parallel resonant frequency of the crystal shunted by about 45pF output is about IVpk pk The inductor used only as a choke is not critical and if the circuit is used below 100kHz it may be replaced by a 1kQ resistor F Brown Lake San Marcos California 741 Amplifier Loudspeaker amp driver peus WWW americanradiohistorv com Simple digital music synthesizer Musical notes of 32 instruments can be generated using this circuit Basic sound patterns of the 32 intruments contained in a 2716 eprom are in 64 byte blocks which are sampled at 64 uniform intervals Six lower address lines corresponding to a memory block of 64 locations are driven by a 7493 counter This is clocked by a variable oscillator whose frequency is determined by nine non locking push switches to control pitch Five locking switches program the upper eprom address lines to select one of 32 memory blocks containing instrument patterns Eprom data outputs feed a digital to analogue converter and loudspeaker amplifier K Balasubramanian NSS College of Engineering Palghat India WIRELESS WORLD MAY 1984 VARIABLE SPEED VIDEO Variable speed video playback The C format broadcast video recorder uses helical scan on lin tape This short series shows how servo controlled head tracking and digital timebase corr
384. uality our final assurance For further details contact us at our new works Blenheim Industrial Park Bury St Edmunds Suffolk IP33 3UT Telephone 0284 3931 1466 ts es e WIRELESS WORLD MAY 1984 PLEASE WRITE IN BLOCK LETTERS CLASSIFICATION WWW americanracdiohistorv com TA TRUE 103 Crotech Oscilloscopes Nationwide availability local to You London amp Home Counties Audio Electronics Carston Electronics Kentwood Electronics Aughton Instruments London W2 London N1 Reading Strood Wales amp West Glevum Instruments Gloucester Crotech instruments Limited 01 724 3564 01 267 5311 0734 698040 0634 724751 0452 31620 East Anglia Electronic amp Computer Workshop Maplin Electronics Ambit International Chelmsford Rayleigh Brentwood Midlands amp North Northern Instruments Universal Instruments Electronic Measurement Services Radio Telephone Service Leeds Leire Leics Manchester Derby Scotland RMR Measurements CIRCLE 073 FOR FURTHER DETAILS 0245 62149 0702 552911 0277 230909 0532 79 1054 0455 20239 1 061 273 4653 0332 41235 Cumbernauld 02367 28170 5 Nimrod Way Elgar Road Reading Berkshire RG2 OEB Telephone 0734 866945 Telex 847073 POWLIN G PAGE AC DC Electronics Corp 84 Airlink Transformer
385. ue nei co mr al P ca UMS Address multiplexer control SPECIAL FEATURE of the system memory is largely determined by the processor Also without the memory the processor board would be rather bare and an extra Eurocard would be needed Integrating the two on one board doesn t preclude the use of extra memory on other boards as indeed happens with the v d u memory Timing dia grams shown will be referred to throughout this explanation ofthe processor board There are three types of mem ory cycle that the Z80 can execute Fetching of an instruc tion or op code from memory is illustrated in the first diagram The second is a composite dia gram illustrating the writing or reading of data to or from mem ory The difference between fetching an op code and fetching data from memory is that the op code fetch is shortened and fol lowed by a special memory cycle intended and used in this case to refresh dynamic memory Three relevant Z80 control signals in accessing memory are MREQ indicating that the current cycle is amemory cycle indicating that memory refresh can now take place and RD which indicates that the current cycle will involve data passing into the Z80 There is also a signal called M1 which becomes active during op code fetches and interrupt_acknowl edge periods and a signal which indicates that data is to pass from the Z80 to the system either signal is used in memory access although M1 takes
386. ur interests Call us now for posts in Design Sales Applications or Field Service at all levels from 6 000 16 000 Technomark Engineering amp Technual Recriatment 11 Westbourne Grove London W2 Tei 01 229 9239 POI i k GENIUS WANTED SOK P Apply in writing to BORED Then change your job 1 VDU and Peripherals Senior service engineer required to support and liaise with 0 M sales orientated personality required Middx To 11 5K car 2 Data Communications 1 years experience in servicing PW Telex or mes sage switching equipment for customer support Berks c 9K car 3 Naval Weapons Communications Support Engineer tor managing lo istics of instal lation and maintenance Berks 9K 4 Service Personnel RAF RN ARMY We have many clients interested in employing ex Service fitters and technicians at sites throughout the U K Phone for details 5 600 per week We are paying very high rates for contract design and test engineers who have a background in RF Microwave Digital Analogue or Software at sites throughout the U K Hundreds of other Electronic and Computer vacancies to 12 500 Phone or write Roger Howard C Eng M I E E M I E R E CLIVEDEN CONSULTANTS 932 The ae 7 ry Berkshire Tel 489429 1646 CLIVEDEN To join our technical department at Utopia recording Studios SSL Studer Neumann and Neve experience an asset to
387. velocity of light in vacuo and k p are artefacts of electromagnetic theory by which it seeks to attribute mechanical properties to a vacuum aether in e m theory c is constant rela tive to this unique aether and not universally Thus the assumption of its universal constancy was not in truth taken over from e m the ory with which it was actually inconsistent but was introduced ad hoc in a curiously ambivalent attempt to reconcile c with the rinciple of relativity Einstein s second postulate was therefore suspect immediately Whether or not we admit it to have been a fudge it is certain that it leads consistently to paradox Nevertheless Einstein indeed accepted that assumption with out evidence in 1905 as if it were as he said a simple law and a natural law Thus what ever my motion light reaching me from any source whatever must always appear to approach me at the same velocity For example suppose that I am look ing towards London from the hills to the north light from the bea con on the Post Office tower shines towards me at velocity c which is fine But you are a pas senger in a southbound airliner lining up for Heathrow According to Einstein the light from the Post Office tower is also approaching you at velocity c exactly despite the fact that you are pass ing over my head at about 300 mile h the velocity of that light is the same for both of us If that is indeed a naut
388. ves may be used either single or double density RS232 serial i o data rates range from 1 to 38400baud with separate transmit receive clocks Synchro nous serial i o format is 5 to 8 bit auto search and sync or asyn chronous 5 to 8 bit with 1 1 5 or 2 stop bits RTS and CTR signals control serial data flow Eight bit parallel data input is buf fered by schmitt i cs Eight bit par allel output drives five t t I loads Three mos i o lines operate event counters pulse timers and Z80 interrupts Four mos timerlines are available for timing and sound generation John Adams is currently working on a high resolution colour gra phics processor using the 7220 and an eprom programmer inter facing to SC84 but with its own pro cessor 1 Timing for Z80 memory read and write cycles Early write cycles are common in larger systems but are not found in most eight bit processors First of SC84 s three main sections the processor with 64K byte ram operating system eprom and logic for dynamic ram bus driver and reset control far right On resetting part of the rom content is loaded into high ram and the rom is then switched out leaving up to 64K bytes for user programs Timing for an op code fetch The Z80 microprocessor has a special register for use with dynamic rams which provides arefresh address comciding with a refresh control signal 280 clock X Cm
389. video output circuit provides both active pull up and active pull down and a line sweep shows that a video excur sion of 100V pk pk can be achieved nearly up to the edge of the band Such an output stage is shown in the circuit diagram of the decoder chip TD3561A Fig 40 Some compensation for the 3dB response drop across the decoder chip and for the loss that occurs in the three transistor output stages may be achieved by adding capacitance across the feedfor ward resistors carrying the RGB decoder outputs In the circuit of Fig 40 capacitances of 27 33pF connected across the 2 79 resis tors from pins 12 14 and 16 R G and B outputs respectively will give a suitable lift The type of output stage used in the Ferguson TX10 receiver Fig 41 isa class A stage in which the lowest transistors 653 652 and 651 form the amplifying stages for each of the R G and B feeds and 659 658 657 emitter followers provide active pull up note that resistors 665 664 and 663 must be low capacitance components Some crossover distortion occurs as the emitter followers begin to conduct on pull up This effect can be seen on a line sweep oscilloscope trace of theoutput waveform but it is diffi cult to discern on inspection of the displayed picture Again the feedforward resistors on the out put pins 12 14 and 16 are shunted with a series LCR combination of 33uH 51pF and a 1kQ resistor for the TX10 to give a flatter Rings fr
390. vy duty use i e disco s or cequire ment for this type of amplifier as the final design will depend on your driving line transformers itegral heatsink bracket lt 0 02 THD TYPICAL necs FE908 S0W 8R 45V 30 00 lee 1913 FE1704 170W 4R 45V 39 00 Pre amplifiers stereo modules with R 1 A A eq M M amp line input needs Send cash with order or quote Acces Mastercharge card no All prices vol and bal pots and input switching Can be used with MC2 module to include VAT P amp P allow use of low O P MC cartridges DISTRIBUTORS CPRIX STEREO 12V 20mA 33 90 Mc2 STEREO 12V 23 00 London Bradley Marshall Ltd mE x 325 Edgware Road NEW SUF Cr North Wilmslow Audio 35 39 Church Street Wilmslow Full details of our complete range including heatsins toroidal No problem but as postage varies so much please write for a proforma power supplies active crossovers etc available on S A E invoice CRIMSON ELEKTRIK STOKE PHOENIX WORKS 500 KING STREET LONGTON STOKE ON TRENT STAFFS PHONE 0782 330 520 HIGH PERFORMANCE FREQUENCY COUNTERS HIGH RELIABILITY LOW COST The brand new Meteor series of 8 digit Frequency Counters offer the lowest cost professional performance available anywhere Measuring typically 2Hz 1 2GHz Low Pass Filter Sensitivity lt 50mV at 1GHz Battery or Mains zi NSM E SPOIL OCS IR BOISE DEEN ODO fu Qo e rs Setability 0 5ppm Factory Calibrated A E r i High A
391. well Road London SES OEE Opening hours 9 00 6 00 Monday Friday GSD 01 701 8668 9 00 1 30p m Saturday S2 01 703 6155 S S 80 Track amp 29 00 for 10 D S 80 Track 31 95 for 10 STOP PRESS Various Opus products are available from WHSmith Spectrum and John Menzies ALL ITEMS ARE GUARANTEED FOR 12 MONTHS AND ARE SUITABLE FOR USE WITH BBC AND OTHER LEADING MICROS To Opus Supplies Lid 158 Camberwell Road London SE5 OEE Please rush me the following ALL PRICES INCLUDE VAT amp CARRIAGE Description Quantity I enclose a cheque for amp Or please debit my credit card account with oF the amountof x My Access Barclaycard ple ase tick No is Name Address E us CIRCLE 036 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 WWW americanradiohistorv com sv rir Wireless Wor over 70 years in i 27 Pausaid by P J Pickersgill andN J Stewart WW design competition second prize winner helps to counter dysarthritic speech Full circuit details 29 ZX81 generation and measurement interface by J Skinner Circuits and programs for timing signal generation and frequency measurement 33 Improving colour tv decoding by D C A Read Countering the loss of h f luminance that can happen in decoder i cs REGULARS 6 Comment 7 News World Telecommunicatior s D
392. whose technical excellence and competitiveness will ensure that large contracts are Ie 98 WWW american S E ENGLAND secured To have acquired the necessary skills and experience to meet this formidable challenge you will probably be at least 30 to 35 years old have management experience especially of dealing with people outside your direct control have experience of customer liaison and project planning and will have developed commercial and business awareness These important new positions offer excellent rewards and conditions with first class future prospects in the thriving division of a leading company in the High Technology and Defence Industries that is part of a highly successful major international group The division has an order book which takes them potentially beyond the year 2000 is committed to developing several new business areas and is poised to move into the world market in a big way TO FIND OUT MORE and to obtain an early interview please telephone FRED JEFFRIES C Eng MIERE in compiete confidence on HEMEL HEMPSTEAD 0442 212655 during office hours or one of our duty consultants on HEMEL HEMPSTEAD 0442 212650 evenings or weekends not an answering machine Alternatively write to him at the address below Executive Recruitment Services THE INTERNATIONAL SPECIALISTS IN RECRUITMENT FOR THE ELECTRONICS COMPUTING AND DEFENCE INDUSTRIES 29 33 Bridge Street Hemel Hempstead Herts HP1 IEG W
393. will become more pronounced as appropriate satellites and earth stations become available In brief Ambit International component suppliers to industry and especially to thehome construction hobbyist have moved to Park Lane Broxbourne Herts though it will beretaining a sales counter at its former Brentwood home o EE OEEEEEEDECECLLELOLLCOILIIEILINILI IGOGXLRCEOLLLES TC LPELLEETEEELETIZELIIEICLL CLLCRRLELEEOLLLCO OJX E Laser etching a path to bigger i cs Anew process using a laser instead of the conventional photo resist has been developed for the production of v 1 s i circuits by Toshiba in Japan Scientists at the R amp Dcentre who were working on the use of lasers as a means of reducing radiation damage caused by the etching radiation discovered that an etching phenomenon occurred when u v light was radiated onto a silicon wafer in chlorine gas Based on this discovery they subsequently demonstrated that a excimer excited dimer laser beam directed at a silicon wafer could etch the surface accurately without the usual photo resist mask The laser used is a chlorine xenon gas tube with a wavelength of 308nm The phenomenon is believed to occur when chlorine molecules are decomposed into chlorine atoms _ by the action of the short wave laser beam The chlorine atoms attach themselves to electrons freed from the silicon surface by the laser radiation The silicon reacts to these chlorine ions to
394. will show industrial applications of installation maintenance and repair The disc will contain a mixture of still frames sequences of operation with a voice commentary and live action sequences The computer graphics will include circuit diagrams for fault diagnosis The union will use the system to supplement their tutors and for self paced student learning The hardware to be used has not yet been selected One option is to combine a Phillips Professional Laservision player with a BBC model B micro using the Microtext language but other approaches are also being considered Epic have produced other interactive video systems including a project for an electronic manual for Rolls Royce and a diagnostic disc on gastroenterology for a drugs company WWW americanradiohistorv com manufacturers it was his contention that we should publish nothing unless the constructor could make all the special parts himself Thus when he developed and published the first constructional articles for television he gave precise instructions how to wind the scan coils first having made the flared winding mandrel out of blocks of wood Such was the quality of his engineering At the outbreak of war he had already published a number of books including his definitive work on television Television Receiving Equipment Not surprisingly he was co opted into the army where he was involved in secret work on military projects throughout
395. work with our young and enthusiastic team of Utopians Call Phil Wairman now on 01 586 3434 OOOO tok Test and Service Technician required for Electronics Company to undertake the running of a small service department Duties would include test and repair of electromechanical devices and associated microprocessor based electronics along with the administration of spare parts stock control Although formal qualifications would be recognised mechanical aptitude and a working knowledge of microprocessors and digital circuitry are considered more essential Good conditions of employment BUPA participation etc 2567 Personnel Manager Roxburgh Electronics Ltd 22 Winchelsea Road Rye East Sussex TN31 7BR University of Leeds Applications are invited for the post of Senior Technician Grade 5 in the Electronics Workshop of the Department of Electrical and Electronic Engineering The workshop staff are responsible for the maintenance of electronic instruments and for the development and construction of electronic equipment for both teaching and research Applicants are expected to have an appropriate qualification minimum ONC and considerable expenence of electromc engineering preferably including computers The salary scale is currently 6279 7332 pa Applications giving full details of age qualifications and experience together with the names and addresses of 2 referees should be sent to Mr W G Black Department
396. y This design provides accurate programmable square and pulse signals and with some limitations synthesized waveforms Synthesized wave gt Yes Read data port aly Increment data value Input voitage WIRELESS WORLD MAY 1984 WWW americanradiohistorv com by J Skinner Fig l For analogue to digital conversion used to measure voltages the computer feeds a digital to analogue converter with digital values starting at zero and incrementing to form a voltage ramp at the converter output Unknown input voltage is compared with the steadily rising ramp and when the two are the same the comparator output changes state Sensing this change the computer stops incrementing the digital value and thus holds a value representing the unknown input voltage 29 Fig 2 Pulse arn by software is simply a matter of writing a program which loops round switching a digital output line on and off on each cycle Mark space ratio of the output signal is determined by proportions of delays x and z Varying these delays for each loop can produce frequency and or pulse width modulation Fig 3 Timer counter connections For frequency measurement input pulses are counted during a period of known length and conversely for period interval measurement pulses of known frequency are counted during a period determined by the input signal Frequency gen
397. y service in the field The 2335 2336 between two channels to allow Choose the 2213 or the 2215 and 2337 all have a fastest sweep detailed examination of timing for superior GOMHz performance rate o 5ns div making them The advanced ogee with single and dual time bases extremely useful for high speed system includes a hands off Auto respectively or the 2235 and 2236 logic and digital applications Level mode ensuring stable for 100MHz bandwidth and many A flip top protective lid triggering on any pulse width or advanced features The 2236 safeguards the front panel from waveform at repetition rates as low includes a counter timer totally transit damage and also houses the as 50Hz integrated into the vertical electronics controls and LCD The 2400 series succeeds the horizontal and triggering systems of displays for delta time measurement earlier Tektronix 400 range as the the instrument providing readout in the 2336 and delta time new industry standard portable measurement capabilities and convenience not previously attainable plus DMM functions in the 2337 oscilloscope Telephone now for your free literature Harpenden 058 27 63141 Maidenhead 0628 73211 Manchester 061 428 0799 Livingston 0506 32766 Dublin 850166 Tektronix UK Limited T PO Box 69 Harpenden Herts AL5 4UP rOnDc Tel Harpenden 63141 Telex 25559 COMMITTED TO EXCELLENCE CIRCLE 067 FOR FURTHER DETAILS WIRELESS WORLD MAY 1984 67 WWW american
398. y and a mains ensures that it will not pass the metering point ofthe premises The main advantage of the system is that it needs no additional wiring The control unit may be plugged into any convenient socket and may be easily moved Each receiver outstation is about the size of a double gang socket and is easily installed The control unit can be used in an immediate mode to switch on or off any remote station It may also be programmed to switch at specific times during the day or on specific days off at weekends for example A c r t monitor displays the status of all the outstations and the programmed times Programs may be easily written to suit any requirements and although the system is self contained it may also be programmed from a host computer The distance at which the system will operate is restricted by the porposed standard for mains signalling equipment In practice this has not proved to be a limitation and the system has worked in many large installations Different applications require different configurations of the control unit but an installation with 50 control units should cost about 7 500 orfor 100 units 13 000 FDB Electrical Ltd Reynard Mills Trading Estate Windmill Road Brentford Middlesex TW8 9NZ WW 218 adaptor charger for 119 95 Advid Electronics 17a Mill Lane Welwyn Herts AL6 9EU WW 219 Pad E seni 3 i 3 oF PX ae WWW americanradiohis
399. y by means of light signals radiated from it a fact which is not generally realised Astronomical aber ration is one of many examples of the effect theory second postulate one cannot hasten toward or ride on ahead of a beam of light its velocity relative to every observer is always and exactly c If that is so reception at M 1s simultane ous by his own definitions and there is no case for denying uni versal time If the observations of M and M differ it must be for the reason Einstein actually gave in that quo tation rather than the reason he thought to give not because the velocity of light is mystically the same for both observers but pre cisely because it is not the same not universally constant but relative It adds up to this one can maintain either the relativity of simultaniety or the universal constancy of c but not both Please take your litter home Inview ofthe simplicity ofthelog ical error that we have been inves tgating where Einstein fell so guilelessly into his own concept ual trap does it not surprise you that so may famous Authorities have so blindly and uncriticall followed him into it Check me 1f you please by looking up the argument in any textbook of your choice or in any popular presen tation such as George Gamow s classic Mr Tompkins In the modern edition it is all done with rockets Having checked you may not be surpnsed to discover tha
400. y into low earth orbit on March 1 1984 Built tested and launched in a few months it represents a real achievement by the University of Surrey team Services and GCHO Among the millions of words that have been written about the banishing of unions at GCHQ suprisingly few commentators have noted the implications of this badly handled affair for other sectors of British and NATO defence communications or come up with a credible reason for the Prime Minister s determination to press ahead with this action at this time The usual scenario has been to blame it on either American pressure following the Prime case as for the introduction of the polygraph machines or simple union bashing There is I would suggest an alternative and inherently more likely explanation the strong wish of the Services particularly Navy chiefs to reverse the post war trend towards having defence communications and signals intelligence networks manned and controlled by WWW americanradiohistorv com a eel civilians The suggestion of de unionisation stemming from within GCHQ can then logically be seen as a move to counter increasing Service pressures against the demobilisation of the defence communications set up For many years the monitoring and interception of the radio traffic of real or potential enemies was the responsibility of the Y service at stations manned largely by the Services though backed up by civili
401. zz 0370 P5200 1000 itp drm ACIOBK 0 230 90131 BUS26 TBA950 0800 2N 53440760 Scho gasp PELET 0940 ERAT ACMIK 0230 80732 0 BU 06 T8A990 0 800 2N 50610200 5285 paa PL5 9 4500 ACMOK 0220 BD 3s BU407 0 TCABOO 0800 2N 52940300 2252 1209 Perez 0630 LED Smm AC 153K 0230 85136 BUAOR T A940 0850 2N32960 300 225305 d220 PCtad osoo RtD 0050 ACH i80 BD37 0 BUSO0 1 thaii700 300 2N 61060400 Seraga ozio CLAS 0550 ACUGK 0200 80138 0 8US26 TOAM120800 2N 61070400 S cags osup PCL86 0350 LED 5mm Aci 0150 80139 BY 126 IDA20020800 2N 61090400 53 33 gag Peisos osso YELLOW 100 AC1B7x 0 200 B0130 Bv127 0 TDA20031 500 58c1i61 1100 PFL200 0850 ACD 0170 B0144 BYI33 D Toaz0201 499 3N 128 0 580 P36 ogg LED om ACIBBK 0230 BDISD BY 16d TpA030140o 3N 4 0850 2SC1172 1 500 GRFEN 0100 ACCU 0 B0137 aY 176 7925220800 noa goon GSC rana plaoe 1900 ACY 19 BD 158 By179 TDA25300 600 NO 020 oscuro tooo PYB 0700 R5630 Full duplex 300 baud 103 compatible filter in 16 pin DIP R5631 Full duplex 200 300 baud V 21 CCITT compatible filter in 16 pin DIP pin for pin compatible with R5630 R5632 Full duplex 1200 baud 212 V 22 combo filter R5633 General purpose programmable filter array for full duplex 103 V 21 DTMF and Videotex AD142 BOGE BY 182 1DA25326 750 PYBB 0480 IN 4002 0040 2515200 250 ADMS BOIS BY184 1425400 700 N Sona pay 25019631300 PYS00A 1600

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