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July - American Radio History

1. E 0 93 0 450 AM iiS 245 2400 STA 072 247 200 HL42DD 350 RG3 1250A VR105 30 1 3CN3A 2 50 6BL7GTA 3 17 AV 10 00 ASELECTION FROM OUR HL90 PCL83 250 35 00 VR150 30 115 3656 095 6818 065 787 250 9001 2 70 STOCK OF BRANDED VALVES 150 PCL85 0 80 RK2K25 6250 VT52 2 50 3CX3 2 50 6885 70 766 250 90506 1350 2 ae 4 350 085 RG4 1000 10 00 VU29 4 50 3 5 150 4 Aes 9140 HR2 200 RK 20A 1200 VU39 150 306 4 50 2 1850 E1524 695 EF732 3 50 Hio foo 080 8 ADS 306 ETE zsa 1998 11 50 EASO 1 00 EF800 11 00 PCL805 0 90 055 1350 2 3 00 RPL16 12 00 w729 1 00 3022 19 50 6857 5 50 8FQ7 1 95 95 1 6 50 2087 11 50 76 1 95 ERE 13 00 JP9 7A 60 00 PD500 3 50 RPY 3 250 w739 150 3W4GT 250 6858 2 50 10D2 125 108C1 1 50 2134 14 95 EA79 mas K391A 9500 510 365 Rpya3 250 X24 100 4B551B 115 00 6BW4 1 50 10F1 0 75 15082 695 2293 14650 070 Eprom 8500 200 250 X66 X65 4 95 4654 59 00 6BW6 5 35 10GK6 195 150C2 150 2599 3750 EACS 250 99 KR6 3 4500 25 2 00 983 250 15 00 X76M 195 4 2504 6
2. or three chips in the bag would nnormally cost to buy Fully guaranteed all C s fuil 100 6 90 200 12 30 300 19 50 DEC CORNER MOSTEK CRT 80E Brand new dual eurocard 280 based VT100 PLUS emulator with graphics etc 499 00 24 11 3 5 Box PSU LTC 385 00 DLV11 J 4 x EIA interface 310 00 RKO5 J 2 5 Mb disk drives 650 00 brand new full spec with manu cturers markings fully guaranteed 101 24 hrs per day Units are made to the FP1500 25 teatures a 50 2 95 100 3 13 CCITT tone spec With 85232 i o levels heavy duty die cast TTL 74 Series A gigantic purchase of an a 25 D skt Units are sold in a tested chassis and DIABLO type and working condition with data Permission print mechanism giving Sav ud modes AUTO ANSWER Data i o offer tull DIABLO QUME standard 5232 25 way D socket Just 2 wire Command compatability fraction Of its connection to comms line Ideal networks etc and ful contro CPM Wordstar etc Original co Complete with data tested ready to Many other features include bi directiona 8 across the board range of 74 TTL series 1 enables us to offer 100 mixed may be required for connection to PO lines superb registration and MODEM 2B Hackers Special fully
3. GANG OF EIGHT The FAST eprom programmer do NOT insect remove when red light on master FAST PROGRAMMING 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 27645 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 anc 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 FAST MONE
4. 86 Analogue Devices 53 Armon Electronics 36 Aspen Electronics Ltd 2 2 68 B Bamber Electronics 60 Barlec Richfield Ltd 24 Barrie Electronics Ltd 42 Beckenham Peripherals 96 Black Star eicere ottenere eroe ot 48 2 48 Carston Electronics 20 Control Universal Ltd seb Cricklewood Electronics 90 Crotech Instruments esee 89 Dataman Designs eee Display Electronics eee Easibind 86 Electronics Brokers Electrovalue EMS Manufacturing 2 2 71 Electronics Wireless World Editorial feature 70 Electronics Wireless World Pliers offer 89 Farnell Foundrometers Ltd Future film Developments make Fylde Electronics Ltd PAGE Gemini Marketing Ltd 42 43 GlobalSpecialities eee 21 GP Industrial Inside Front cover Outside Back Cover Grandata Ltd 84 Greatech Electronics esses 16 Happy Memories eee 10 Harris Electronics London 20 Harrison Bros Hart Electronics Kits Ltd Hawke Electronics Ltd Henrys Aud
5. SN models BNC sockets Bench portables UK C P 1 00 2 pocket counter 65 SERIES UK made 0 1HZ resolution B digit LEO display mains operated 220 240V AC switchable gate times 89 00 115 00 59 00 1000 2 range 5 2 10 10CMHZ 120M H2 typical MET600 3 range SHZ 600M HZ 700M HZ typital MET1000 3 range SHZ to 16HZ 1 2GHZ typical 1 Optlonal 6 x nicads 9 95 SABTRONICS New models LEO display switchable gate times 81104 8 digit 20HZ to 100 7 79 00 8610B 9 digit 1087 to 600M HZ 109 00 8000B 901011 2 to 1GHZ 149 00 85008 9 digit up to l 6HZ 239 00 THANDAR UK made LCD displays with batteries 040 8 digit 10 2 to 40MHZ LCO 1HZ resolution AOmV sensitivity 2 gate times with batteries t 20 00 TF200 8 digit 200 2 LCD 2 ranges resolution Ippm AHS sensitivity 5 gate times with batteries 165 00 Optional carry case 5 95 AC mains adaptor 6 95 200A Pocket B digit 20HZ to 200MHZ 2 band LED display with battery 01 2 resolutlon 10 sensitivity with battery 69 50 PRESCALERS Suitable lor most types of counters to extend range BNC sockets 600 40MHZ to GOOMHZ 1 AMS direct powered by counter TP1000 100 to 1000 7 complete with AC adaptor P S 25mV AMS sensitivity Optional probe kits suitable for all modets
6. au 1 0 JUaWINba ysy jo Ajddns au Ajijiqedeo 5 5 10 5914049913 INI NHOHL 99 JULY 1984 ELECTRONICS amp WIRELESS WORLD 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 microprocessor applications Current opportunities are for Telecommunication Technical Officers Two levels of entry providing two salary scales 6262 8580 amp 8420 9522 Minimum qualifications are TEC SCOTEC in Electronics Telecommunications or a similar discipline or C amp G Part 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
7. distributor N d THORN EMI Instruments Limited Road Dover Kent CT17 Telephone 0304 202620 Telex 96283 CIRCLE 76 FOR FURTHER DETAILS AWW ame Om 0474 813225 INTEGRATED CIRCUITS 7 STK433 7 95 AN124 2 50 MC1351P 1 50 STK437 7 95 AN214Q 2 50 MC1357 2 35 5 439 7 95 AN240P 2 80 1358 1 58 TA7061AP 3 AN612 2 15 MC1495 3 00 TA7108P 1 00 AN7140 3 50 1496 125 7120 1 65 7145 3 50 145106 7 1 50 7150 2 95 7 95 7146 3 95 BA521 3 35 1723 0 50 7176 2 95 1352 1 75 3357 2 75 7203 2 95 CA3086 0 46 12318 1 75 TA7204P 215 6016 2 50 ML2328 250 TA7205AP 115 1377 350 5 5807 6 75 7222 1 80 HA1156W 1 50 PLLO2A 5 75 TA7227P 4 25 HA 339A 2 95 SAASOOA 3 50 TA7310P 1 80 1551 295 SAA 025 725 TA7313AP 2 95 141230 1 15 5 5010 6 35 7321 225 LA4102 295 5 55605 1 75 7609 3 15 LA4250 2 95 5455705 1 75 TA7611AP 2 95 4400 4 15 SAS580 285 550 0 25 LA4420 1 95 519018 485 570 195 44422 2 50 519178 6 65 21 LA4430 250 511310 180 3 50 1C7120 3 25 511327 1 10 TAA661B 1 20 LC7130 3 50 5113270 1 10 700 1 70 1 7131 5 50 SN76003N 1 95 1208 0 95 67137 5 50 SN76013N 1 95 120 1 15 LM324N 0 45 SN76023N 1 95 1207 1 05 LM380N 095 SN76033N 1 95 TBA120U 1 00 LM383T 2 95 SN76110N
8. 10 E 54194 4 99 1 aduewsopad 20 5 sjuauodwod E i i 5 45 sepes 152 pasijeisads SYFANIDNA 91534 LNAWdINOA 1531 S92 ep pue Sanbiuyda 2 1815 Jeped JAIL 10 Buisse 2oad 5 pue paads yBiy 1591 pue NDISAA TIVLIDIA GNV ANDOTVNY exuere pm 91U0 392 3 syoaloud Mau 0 Jaquunu 0 ay 5 sno 10 ed adualadxa ay 10 151 8 4 5 5 2 YIL y ajdoad 1134 0 42313 e 20 Burx00
9. CIRCLE 62 FOR FURTHER DETAILS 88 9 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com WELL WORTH SECOND LOOK No you re not seeing double just the Crotech 3132 s in action This unique feature using two Crotech component testers gives you the benefit of checking an active or passive component against a known standard Complete circuits can also be checked using signature techniques But that s not the only new feature The 3132 has three DC source outlets available on the front panel capable of powering most solid state circuits Dare we say that the 3132 is the nearest affordable scope to come near to being a complete test system 2 Stephenson Road St Ives Huntingdon Cambs PE17 4WJ Telephone 0480 301318 V REDA Dial VECS SUI UT CIRCLE 41 FOR FURTHER DETAILS HIGH QUALITY PRECISION PLIERS AND CUTTERS precision box jointed pliers and cutters are manufactured West Germany and are of extremely high quality They are supplied to and used by the electronics industry They all have double leaf springs moulded on PVC ELECTRONICS id grips and polished heads The cutters have induction hardened cutting edges Wireless SW As a little test of the quality and the squareness and fit of the jaws we tried holding pieces of paper with the pliers and cutting the pap
10. Fed Executive Recruitment Services THE INTERNATIONAL SPECIALISTS RECRUITMENT FOR THE ELECTRONICS COMPUTING DEFENCE INDUSTRIES 25 33 Bridge Street Hemel Hempstead Herts HP1 IEG 2634 GROUND ELECTRONICS AND TELECOMMUNICATIONS UNIVERSITY OF OXFORD Dyson Perrins Laboratory ENGINEERS TECHNICIANS Earnings over 2 years not less than 23 500 tax free PLUS free accommodation and meals expert medical care personal accident insurance PLUS 21 days UK leave at 17 week intervals with free air travel to and from Heathrow Applications are invited for immediate and forthcoming bachelor status vacancies with our Comoany in the Sultanate of Oman The work involves maintenance of modern military equipment associatec with the three branches of the Armed Services Ideally applicants should have a thorough knowledge of techniques and have been employed for a minimum of 5 years within the field of one or more of the following mobile and static military radio systems associated antennae and ancillary equipment cryptegraphic and telegraphy equipment weapons fire control systems and navigation aids used air traffic control If you feel you are suitably qualified and interested in joining our Company please write giving a brief summary of your qualifications and experience to The Company Personnel Manager Airwork Limited Bournemouth Hurn Airport Christchurch Dorset BH
11. LITERATURE RECEIVED The functions of many different instruments are combined into one unit in the Griffin programmable scientific instrument or GiPSI Starting from a single or dual input multimeter it may be converted into a variety of other instruments by the addition of plug in modules and overlays to show the functions of the touch sensitive membrane keyboard Among the modules are a pH meter measurements of pressure magnetic flux timing and counting and many more The meter can also be interfaced with a computer as part of a data acquisition system Full details in a brochure from Griffin amp George 285 Ealing Road Wembley Middlesex HAO 1H WW273 A number of programs for biological experiments are included in Micros in the Lab Designed for use with the ZX Spectrum computer full software and hardware details are given in this duplicated booklet The centre that publishes it can also supply a number of components to ILEA schools ILEA South London Science Centre Wilson Road London 5 5 8PD Telephone 01 701 2224 ILEA publish two magazines for school micro users Computers in Primary Schools newsletter for primary schools and Educational Computing for secondary schools Both come from the Inner London Educational Computer Centre John Ruskin Street London SE5 0PQ WW275 THE SMC MARINER 99 This newly designed micro processor controlled 1 watt VHF transceiver allows for the first time a ma
12. 0 80 ZTX108 0 12 2N708 0 25 23702 011 25303 1 50 AFI06 0 35 BCl36 0 19 BCY42 030 pris 028 0208 2 00 79 012 2 75 ZTXIO9 012 2N930 025 2N3703 011 25322 3 50 4 0 75 BCI37 019 BCY43 0 30 gris 030 0 40 OABI 0 7 2 00 ZTX300 043 2N1131 274 011 28324 3 50 075 47 0 12 BCYS8 0 19 BFIg3 028 BY126 0 13 85 0 17 OCI9 300 ZTX30 014 2N1132 030 2N3705 011 58701 2700 6 0 75 BCI48 0 12 BCY70 047 028 27 014 OA90 0 08 OCI40 4 00 ZTX3O 0 18 2N1302 1 20 2N3706 0 11 25745A 095 AFII7 075 BCl49 0 13 BCY7 0 18 priss 0 30 2 61 0 17 0 08 OCI4 4 25 2 303 018 2N1303 080 2N3707 0 11 25746 095 AF139 0 33 BCIS7 043 BCY72 047 0 14 Series 95 0 08 OCI70 125 ZTX304 0 20 2N1304 120 23708 040 AFIB6 1 00 BCI58 043 BCZ 175 0 12 BZYS8 010 OA20 015 125 ZTX311 013 2ND05 10 2N3709 AF239 0 39 159 0 13 BDIIS 0 42 0 13 Series 202 0 15 OC200 1 50 2 34 0 25 231306 1 50 243710 0 10 CV Devices 400 BCI67 011 170 Brig7 0 14 CRSU 40 0 OA2I1 1 50 OC201 2 50 2 50 0 14 2NI307 110 2N3711 0 10 Large stocks 400 BCI70 0 11 BDI23 280 BF200 0 40 CRS340 0 75 OAZ200 1 50 OC200 2 75 ZTX50 0 14 2NI308 175 2N3771 140 Prices on 1 40 BC171 0 1 0124 2 00 BF224 0 25 CRS360 0 90
13. BRITISH 50514104 HOW TO LOG IN TO BLAISE LINE T EL L m m jeg by direct dial a Dial he computer 0279 25411 or one af the nodes see below 6 When a whistling tone is heard engage the modem or coupler c Wait 5 seconds and then type the letter upper case d When receive the message PLEASE ENTER LOGIN type 7LOGIN When FEN PLEASE NIERO R SEKID FASSWORD for Three lines of masking to print and then enter your USERID and password wart f You will then be connected to the UFCMARC file F ey for direct dial node numbers 1 Address for information 2 BLAISE LINE 9 BSD inde Logging on or in like Prestel and many commercial data bases the British Library s BLAISE system asks for pas swords The start of a program in Apple Basic in Prestel telesoftware format With the help of suitable communications software a complete program can be down loaded automatically in about the time it would take to load from tape Aladdin s Cave 70071490 03424 35216 1 QUILH 43447 GL 244 CUL 61 450 58345000 MCR TURNSAIL 1503 VIR H 7 56 IRET URNUIL 70034 Vie 341 GL 25024 24 241 154 2447 34501014527 TURN4ILL 200241 241447 GL 34 2417 5 LJO 2 4601 D2492 7 250 Ve 347 GL TU
14. 3 00 each BBC graphics screen dump utility program 8 50 Carriage and Ins 10 00 VAT EPROM COPIERS TERMIPRINTER 1 i 8855 gt ikit Massive purchase of these desk top TERMINALS iod C EY NA E qu printer terminais enables us to offer you 1 0 75 ohm composite video signal via 50239 these quality 30 cps printers at a SUPER FROM 195 CAR VAT socket on rear panel Bandwidth of the unit LOW PRICE against their original cost of Fully Hedge ed industry standard ASR33 data is estimated around 20 Mhz and will display keyboard cassette interface serial and parallel over 1000 Unit comprises ol full QWERTY terminal Many features including ASCII most high def graphics and 132 x 24 lines data 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 burns However where burns exist they are NEW GANG OF EIGHT intelligent 280 typewriter Variable forms tractor baud 8 bit paper tape punch and reader for only apparent when monitor is switched off controlled gang bang programmer for ALL paper upper lower Po Standard H3232 off line data preparation and ridiculously Although unguaranteed ali monitors are single 5V rail EPROMS Copies up to 8 27128 serial interface interna
15. Lo series resonate the remaining half coil with the 680pF at 14BIFILOR 14 014 18TBIFILOR 17 0117 2 93MHz or use wider signai bar corner on enda not3uHas shown in circuit Resonate at 2f 16 Setfor fiiter cut off Not critical 18 Painton or Sigma choke 150 Painton Sigma choke Itis best to set up A and B group delay equalizer sections in isolation i e no other equalizer or filter component in the circuit thus check each stage of the filter and equalizer one section ata time La and L measured across outer pini e total inductance 200 10k series coil assembly Neosid E2 coil assembly Use eC or 42 Seg 0125 0 1mm wire ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com in relation to transitions in the increasing video signal A pair of four turn coils built into the scanning yoke and placed in the line scan coil plane provides line aperture modulation of the scanning field A restricted spec trum of the luminance signal in the range 2 to 3 5MHz is ampli fied amplitude limited and used to drive the extra coils in the scan yoke The block diagram is shown in Fig 98 The additional circuit feeding these coils need only con sist of a simple CR differentiator back to back diode limiter and class B output ampl
16. Kalee Flutter Meter Siemens Transistor Power UnitQ 30v 2amp TF8018 125 Airmec Wave Analyser Type 853 30Khz 20Mhz Marconi AM Signal Generator 10 310Mhz Type TF801A 1 Marconi Standard Signal Generator 15Khz 440Mhz Type TF867 Marconi RC Oscillator20Hz 200Khz Type TF 1101 Marconi AM FM Signal Generator Type TF 995A 5 Marconi VHF Signal Generator Type TF 1064B 5M Marconi Tx amp Rx Output Test Sel Type TF 1065 Pye Modulation Meter 68 510Mhz Type MM1 Airmec Sweep Signat Generator 20Hz 200Khz Type 352 Marconi Universal Bridge Type TF 8688 EMI Wide Band Amplifier Plug in Type 7 1 Advance Oscilloscope Type OS15ALP Tube 3Mhz Advance Oscilloscope Type 0525 Twin Beam 3Mhz General Radio Microwave Oscillator Type 1360B 1 7 4 1Ghz Wayne Kerr Component Bridge 8521 MarcontOsciliator Type TF 1246 40Khz 50Mhz Wandei amp Gottermann Level Meter Ty pe 43 10Khz 14Mhz Sullivan RCOscillator 40Hz 125Khz 85 Electrohome 9 Video Monitor metal case Aztec 20 Video Monitormetal case 85 Marconi UHF Signal Generator Type TF 1060 2 45010 1200M Hz Marconi VHF Alignment Oscilloscope Type TF1104 1 Sander Oscillator Type CLC2 4 2104 5GHz Marconi 100 Watt 7db Attenuator Type 5280 15010 185MHz Bruel Kjoer Vibration Meter Type 2502 Pye Aerial Tuner Unit Type ATU 4 210 9 2 Pre set Electronics Pulse Generator with Clock Generator Rohde amp Schwarz 2 1 Diagraph Type BN 3562 30010 240MHz
17. Wye Winding Co outre eese tem OVERSEAS ADVERTISEMENT AGENTS France amp Belgium Norbert Hellin 50 Rue de Chemin Veet 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 Media Japan 8 212 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 5 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 Miami Beach Florida 33140 Telephone 305 532 7301 Tim Parks Ray Rickles amp Co 3116 Mapie 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 86
18. the space two dot rows between adjacent display lines The two dot horizontal space is used by lower case letters with descen ders g p q etc The fastest event in the v d u is sending of a pixel to the display and a signal at this frequency is generated by the 12MHz dot clock oscillator This signal is divided by six in a programmable divider to give a signal running at the char acter display frequency the char acter clock This division and all operations at the dot frequency is done outside the controller as the frequencies involved are too high for most technology used in the HD6845S Note that the charac ter generator is an eprom Not only are they cheaper than pro prietary character generator roms but they allow you to change the character set to suit your own requirements Even the number of dots making up a character can be altered up to an eight by 16 matrix but this is rather adv anced work Circuit is a four bit pro grammable counter It provides a carry pulse at pin 15 as it passes through its maximum count value binary and this signal loads the binary value on pins six to three instead of allowing the counter to count on to zero on the next dot clock pulse This valueis binary 1010 denary 10 so the counter counts through six states binary 1010 to 1111 before repeating Divider output C pro vides the character clock signal fed to the controller An inverted
19. 400 4 60p many inc specials see our CAT LED LAMPS R Red G Green Y Yellow Large diffused 1 ASD 650 Y5D Smal diftused R30 8 G3D 12p Y30 12p Micro 0 1 RIM 27 29 YIM 29p Large clear RSC GSC vsc Super bright high efficiency Large 100 umes brighter ASU 38p 650 42 YSU 42p Rectangular Stackable LEOs RSR 18 658 190 Y5R 21 LIN ICs AY15050 AY3B910 AY38912 CA3048 CA3058 CA3090AQ 1 CA3130T CA3140E CA3140T HA1366W 1388 1 7106 1 7107 1CL7611 8038 1 7555 1 7556 LC7120 C7130 C7137 16347 17351 17353 LF355 LF356 LF35 LF398 3352 LM348N LM349N LM350K 1 3795 CL M380N14 LM380NB LM381AN LM381N LM382N LM383T LM386N LM388N 1 M391N60 M381N80 LM723CH LM723CN LM725CH LM725CN LM741CH LM741CN LM741CN 4 80 LM747CN 69p LM74BCH 1 00 LM748CN 42p LM1871 325p 1872 4 39 1877 LM1886 M1889 2907 LM2907NB LM2917N 1 2917 8 LM3900 LM39 LM3914 3915 1 13600 MF10 NE531N NE543N NE544N 555 556 558 NE560 NE565 566 NE567 570 NES71 5534 4194 4195 4558 5 76477 5 76003 SN76013 N76023 SN76033 TA7204 7205 7222 TA7227 500 5000 510 5100 TBA520 5200 530 TBAS300 540 TBA540Q0 550 5500 56 570 TBAS700 TDA1002 TDA1003 TOA1004 TDA1004A TDA
20. 470 00a Gremlin debug Rom 28 00d 80T DS DD Pkt of 10 een 30 00c 6502 2nd Processor 175b Computer Concepts Graphics 28004 2 DoubleSidedDisc Each 4 50c AcornElectron 169 00b ExMON FLOPPICLENE Drive Head Cleaning 14 50c BBC Teletext Receiver 195 00a TOOLKIT 0 009 DiscLibraryCase 1 90d ELC A Printmaster Rom 80 728 009 DiscFileCase30 40 8 00c UPGRADE KITS Communicator Rom 659 005 Vise Lockable Case 30 40 15 00c Ato BUpgrade Kit 60 00d Disc Lockable Case 60 70 27 00b DFS Kit E95 00d Installation 15 00 COMPATIBLE 5 25 DISC DRIVES SOFTWARE Econet Kit 55 00d Installation 25 00 include cables manual format disc ACORN MERLE BUSINESS SOFTWARE Speech Kt E47 00d Installation 10 00 499K 40 Track Teac 18500a Invoicing Stock Control Accounts Payable 100K 40 Track with psu Tec 145 00a Accounts receivable Order processing ECONET ACCESSORIES 200K 40 80 Track Teac 175 00a System Each 22 65d Printer Server Room 41 00b File Server Level 1 8600p 200K 80 Track with psuTec 2190 00 GEMINI Business Full Range Fig Senor level 216 000 4O0K BOTackDS Mitsubushi P19000a ACORNSOFT Full Range gt gt i o 400K 80 TDS with psu Mitsubushi 225 00a ACORN LANGUAGES including BCPL LISP ALL PRICES EXCLUDE VAT
21. BLOCK LETTERS PLEASE MERETUR Address 5 amp ores tt cott ro tatit Registration No 735718 o 7 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com NEW PRODUCTS Amstrad sounds off On paper Amstrad s CPC464 microcomputer scheduled for June introduction seems an ideal all rounder cheap fast 64K ram high resolution graphics and with a colour or monochrome monitor included in the price Of interest to we of technical bent there s the promise of even more including full access to the 4MHz Z80 processor CP M Basic interrupt operations assemblers and disassemblers With built in cassette recorder and direct drive green tube monitor the basic version costs 229 and fora further 100 one can have the colour monitor version Monitors will not be available separately Disc based monochrome and colour monitor versions will cost 429 and 529 respectively including CP M and Logo a US import language for educational programs The Japanese Hitachi format IBM data format 3in disc drives should be available separately for around 200 There is as yet no CP M compatible software on 3in disc At these prices one couldn t buy the parts and build one cheaper Assuming no hidden snags the only remaining question is reliability Bill Poel general manager of Amstrad s new software company Amsoft and
22. Reverse and misplaced insertion checks Constant power supply monitoring and system checks Checksum illegal bit test blank check compare and self check cycles RS232 serial interface as standard Single key programming operation Ex stock P8000 695 12 del VAT WWW americanradiohistorv com GPP row Accessories for the EP8000 and EP4000 range NEW BP5 Bipolar PROM Programming Module Allows the EP8000 and EP4000 to pro gram copy verify a range of 21 Signetics bipolar PROMs up to 2k x 8 bytes sizes Ex stock 228 VAT O SA27128 Adaptor Allows EP8000 to program 27128 EPROM Ex stock 69 VAT 1 UV141 EPROM Eraser Erases up to 14 devices simultaneously safety in terlocked electronic timer Ex stock 78 VAT 1 Prinz Video Monitor Green phosphor high resolution video monitor suitable for EP8000 and EP4000 Ex stock 99 VAT Contact us now for a complete pro duct data pack Tel Plymouth 0752 332961 Telex 42513 4 DIGIT AUTORANGING MULTIMETER THE DM141 G FARNELL METER This 4 digit autoranging digital multimeter measures a c and d c volts and current resistance and dBm A C measurements and dBm are true r m s with a frequency response of 45Hz to 20kHz For automatic ranging select the required function connect and read The DM141 will automatically select the best range and
23. nmos controller and memory it forms the character v d u The NEC uPD7220 is one of a new generation of graphics con troller designed for i o mapping but offering a degree of internal complexity which overcomes many of the objections to i o mapping Designed to control up to 256K words 1 word 16 bits of dynamic memory it appears to the c p u as two i o ports and optionally a d m a channel Using i o ports for commands and d m a for data rapid access to v d u memory is possible For graphic functions such as shape drawing or filling areas the 7220 can be given parameters and then commanded to draw which it can do at over one million picture ele ments pixels per second with out further c p u involvement Other internal features are full refresh zooming expansion of one part of the display to fill the entire screen and the option of flash free memory update i e memory access during flyback period only Details of the gra phics display and of programming techniques for both controllers will appear in a later article Figure 1 shows the character v d u circuit As most c r t con trollers the HD6845S is designed Character clock IC34g pin 12 CARRY Pin 7 1 4 Display cycle begins Character 0 latched 068457 address lines R WM outputs 10315 latched data outputs Character generator outputs Display enable timing 1357 pin 9 Skewed DISPTMG signal becomes active
24. rovro 65 550 CIRCLE DETAILS The Archer Single Board Computer The ARCHER a new 280 based single board computer for professional applications After a power failure it carries on where it left off and the on board watchdog guards against software crashes SDS ARCHER einge board computer 150 SDS BASIC ROM 30 30 FEATURES SDS ARCHER CASED with on off 4MHz Z80A switch mains connector lead etc 200 2serial ports Counter timer chip CMOS battery back up Bus expansion connector OEM and distributor discounts available On board mains power supply Sherwood Data Systems Ltd 4Parallel ports with handshaking Sherwood House 4 Bytewide memory sockets up to 64k The Avenue Power fail and watchdog timer circuits Farnham Common High quality double sided plated through PCB Slough SL2 3JX Sherwood Data Systems ltd CIRCLE 76 FOR FURTHER DETAILS 92 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com Appointments Advertisments accepted up to 12 noon Tuesday July 31st for August Sept issue subject to space available DISPLAYED APPOINTMENTS VACANT 17 per single col centimetre min 3cm LINE advertisments run on 3 50 per line minimum 25 prepayable BOX NUMBERS 5 extra Replies should be addressed to the Box Number in the advertisement c o
25. 150 190 450 0 20 4 400 70 00 2 1041 1400 58468 2 80 6F32 125 1307 320 5663 196 DETIG 28 50 ECC86 275 Eves 595 MB195 650 27 00 TY7 6000A ZM1082 9 00 SRAGY 280 6F33 7 00 13087 295 5670 325 DET 8 28 50 ECC88 0 85 EY86 87 0 50 M8196 5 50 QQE06 40 365 00 ZM1084 10 00 514 5 95 6FG5 1 95 13 1 115 00 5672 4 50 DET23 35 00 ECC91 2 00 055 8204 550 39 50 Ty8 600W 2 1177 9 00 5046 195 6GH8A 0 80 1457 1 00 5687 4 50 DET24 39 00 0 72 Eygi 550 M8223 450 00 02 6 16 50 5 00 ZM1202 55 00 50468 2 50 6GK5 150 17 8 0 95 5692 350 DET25 2200 ECC189 0 78 150 M8224 200 105 50 TYS2 250 ZM1263 400 5VAG 125 6666 195 178 275 5696 275 DET29 015 350 Eygo2 M8225 350 Qavo3 10 375 00 7 1612 300 5Y3GT 195 6GV7 250 1803 160 5704 260 DF91 0 70 5 3 50 5 075 ME1401 2950 Mullard 9 50 18 20 275 120 57467 085 6GW6 250 1963 17 00 5718 6 15 Droz 6060 4 0 60 E240 275 402 2950 20 59 1195 18367 195 6 3012 070 6H3N 1 10 19 4 2395 57258 250 DROB 65 1250 174 275 1501 1400 18 50 U24 2 00 1822 10 00 6A 203K 9 00 6H6 135 19H5 33 50 5726 250 97 100 2000 12 00 E380 075 4 350 00 03 208 025 0 90 1824 1495 6A8G 150 6H6GT 195 1906 9 00 5727 2 50 DHe3 1 20 085
26. Assembly Testing of VHF and UHF equipment Cable Television Communication Equ Filters amplifiers etc Contact JT ELECTRONICS LTD Unit C4 Industrial Estate Button End Harston Cambs CB2 5NX Tel 0223 871239 Tix 21792 Ref 3575 DESIGN SERVICES Electro design 4 velopment and production service available tor digital and analogue instruments RF Transmit iers and receivers telemetery and rol systems 20 vears experience R C S Electronics W olsey Road Ashford Middlesex Phone Mr Falkner 3661 8341 P C B s amp PANEL LABELS to your require ments Design Prototypes Production G N SLEE CUSTOM PRODUCTS 78 Derry Grove Thurnscoe Rotherham Yorks 563 Telephone 0709 895265 2401 stockist Design amp Development Complete Artwork Service Camera Work Prototype thru to Production PCB Manufacture JASSY 5 Cork Street Eccles Maidstone Kent ME20 7HG TELEPHONE 0622 79987 TELEX 965633 2348 CIRCOLEC THE COMPLETE ELECTRONIC SERVICE Artwork Circuit Design PCB Assembly Test amp Repair Service Consultancy Prototypes Final Assembly Full PCB Flow Soldering Service Quality workmanship by professionals at economic prices Please telephone 01 646 5686 for advice or further details TAMWORTH MANOR 302 310 COMMONSIDE EAST MITCHAM 1 EE ENEN Gompezitive T erret W
27. Name and address to be included in charge if used in advertisement ie Box No Allow two words plus 5 e Cheques etc payable to IPC Business Press Ltd and cross amp Co ELECTRONICS amp WIRELESS WORLD JULY 1984 103 WWW americanracdiohistorv com eo Hitachi Oscilloscopes 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 sents the best value for money available anywhere V 212 20MHz Dual Trace V 209 20MHz Mini Portable V 222 20MHz illustrated V 509 50MHz Mini Portable V 203F 20MHz Sweep V 353F 35 2 Sweep Delay V 1050F 100MHz Quad Trace Delay V 134 10MHz Tube Storage V 422 40MHz Dual Trace 6015 10 2 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 Thuriby Reltech 46 High Street Solihull W Midlands B91 3TB CIRCLE 31 FOR FURTHER DETAILS INDEX TO ADVERTISERS Appointments Vacant Advertisements appear on pages 91 103 PAGE A amp H Supplies 1 enn 6 Airlink Transformers Ltd 20 AM
28. The Publishers take all reasonable care to ensure that classified advertisements are genuine but readers must satisfy themselves that they will be obtaining what they require before entering into transactions particularly if they involve large sums of money 2519 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com Its easy to complain about an advertisement Once you know how One of the ways we keep a check on the advertising that appears in the press posters and in the cinema is by responding to consumers complaints Any complaint sent to us is considered carefully and if there s a case to answer a full investigation is made If you think you ve got good reason to complain about an advertisement send off for a copy of our free leaflet It will tell you all you need to know to help us process your complaint as quickly as possible The Advertising Standards Authority If an advertisement is wrong were here to put it right ASA Ltd Dept 1 Brook House Torrington Place London WCIE 7 This space is donated in the interests of high standards of advertising ASSIFIED ADVERTISEMENTS Use this Form for your Sales 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
29. 33 40 20 0 20 or 25 0 25V 50V 25V 0 5 1 413 140 1 2 503 150 2 A 4 868 1 84 3 5 1036 190 4p 8 1410 212 6 5 12 1801 220 8 16 2452 270 0 20 3023 300 2 24 3618 320 60 30 or 30 0 30 Pri 2x120V 2x30V Tap Secs 6 8 10 12 16 18 20 24 30 36 40 48 60 24 0 24 or 30 0 30V 60 30 Price P amp P 0 5 1 4 150 1 2 715 150 2 4 39 190 6 1331 200 4 8 1515 220 56 10 1916 220 6 12 21 85 2 65 8 16 3072 300 10 20 3576 330 12 24 4122 350 MINIATURES INVERTERS Price v PAP 05 1 537 120 TDROIDALS 2 4 1469 220 Wound to spec 6 1779 240 to SKVA 5 p 10 3223 320 6 12 4036 350 EXPORT ENQUIRIES 8 16 4403 375 WELCOMED 0 3A 15 241 90 SecV A Pri P amp P 1 5 319 10 303 2 3 11 90 2 425 120 6x2 1 2 3 45 1 20 4 2 491 160 9 0 9 1 259 90 6 3 175 150 9x2 33x2 241 90 8 4 898 160 89x2 5x2 3 36 120 10 5 982 180 89 2 Ax2 427 140 12 p 6 1089 190 15x2 2 2 241 90 16 8 1297 212 120312 05 311 90 20 10 1746 244 20x2 3 2 3 39 120 30 15 21 69 264 20 2 15x2 1 50 50 60 30 4445 0 2012 0 83 41 5120 450 1220 9 413 130 15 20 2 1 2 5 60 1 60 96 48V Pri 2x 120V 1527x2 5x2 4 83 140 Secs 2x 36 48V 1527x21Ax2 7 30 1 60 1000W 350 00 1 20 24 30 or bid 2000W 709 00 15 osa 1 ais 12 CONSTANTVOLTAGE 1222 432 140 _ TRANSFORMER 1 2A 6 1 60 Spike freestable mains 3M 6 810 185 250
30. 34 Load shift rea with char 0 Character 1 latched for use in raster scanning sys tems i e with a normal televi sion like display where the cathode ray tube spot writes lines across the screen from left to right while being progressively swept down the screen This means that one character is not completely drawn on the screen before the next the spot moves across the screen succes sive character codes are taken from v d u memory and just one row of dots from each of the corresponding character pattern is taken from the character gener ator rom and displayed on the v d u At the start of the next c r t line the v d u memory add ress reverts to the same value as that of the start of the line but a different row of dots is selected from the character generator Only when the last dot row has been drawn is the memory add ress allowed to step to the next area of v d u memory The num ber of characters on line and the number of dot rows or rasters is set by loading values into the con troller when the Z80 is initializing the system These factors control v d u memory address lines M and row address lines In this system displayed char acters are six dots wide by nine dots high this pattern includes the space one dot column between adjacent characters and Load shift reg with char 14 character 2 latched X don t care 0 02 character zero bit zero etc Display enabled
31. 5 25 M8081 9 82 PCF801 2 50 5130 6 00 1 6400 6AB4 1 75 6 4 2 50 30L1 1 50 5965 3 50 BT95 129 90 EBF83 1 75 EL83 6 00 M8082 9 69 PCF802 250 130P 6 00 102 00 6AB7 3 0 6K6GT 275 301 15 2 00 6005 2 25 CBL31 4 00 1 50 2184 2 25 M8083 8 58 1 70 STV280 40 1120 395 00 6AC7 3 00 6K7 3 00 30117 2 00 6021 4 50 CL 400 EBL3 4 00 EL86 2 75 M8091 1043 PCF806 1 70 14 00 yD1240 450 00 GAF4A 4 25 6K8 3 00 3084 150 6057 10 23 3 00 90 1 25 EL90 2 25 M8096 6 80 PCF808 1 70 STV 280 80 2759 25 00 6AG7 3 00 6KD6 7 00 30P19 2 50 6058 12 34 20 00 8 00 EL91 9 69 8097 810 PCL82 2 00 21 0 7 1000 800 6AH6 5 00 6166 300 30PLI 3 00 6059 6 00 GA 22 00 1 75 EL9S 200 809 6 15 PCL83 3 00 504 5 00 ZM1001 8 00 6AKS 599 6L6GA 3 00 30PLI4 1 80 6061 600 C3JA 22 00 57 380 00 ELIS6 3000 M8099 800 PCL84 2 00 SU42 10 00 ZM1020 9 00 6AK6 250 6L6GC 300 30PLIS 180 6063 3 75 DA41 25 00 ECC33 4 50 EL360 8 50 M8100 9 52 PCL85 1 50 TD03 10 35 00 2 102121 9 00 6AL5 1 50 6L6GT 3 00 35W4 1 00 6064 8 58 DA42 1870 ECC35 4 50 ELS00 S04 3 00 M8136 1023 186 2 50 TD03 10F 35 00 ZM1022 9 00 6AM4 4 00 6L7 250 5005 1 50 6067 10 23 DAF9I 1 75 ECC40 4 50 ELSO9 7 00 M8137 10 23 PCL805 85 2 50 TTIS 5000 7 1023 9 00 5 9 69 6N2P 250 7581 6 05 6072 6 00 DAF 175 175 EL82 13 00 6
32. 50 line period 149 20 sec O 43Vpp f c 1 9MHz 10X line period 72 9 sec 0 88 fse 3 9 2 1X line period 65 5 0 98 fsc 4 amp 4 3 amp 4MHz X1 line period 64p sec 1Vpp 4 43MHz 3X line period 62 6 sec 1 02Vpp 4 52 2 10X line period 58 1j sec 1 1 4 88MHz 50X line period 41 3 sec 1T55Vpp 6 87MHz video timing the consequence of dropout can For example the destruction of a burst by dropout renders the following chroma information meaningless since the timing of the suppressed car rier is lost Dropout compensa tion is thus a major function of timebase correctors If the variable speed playback is employed the effect is to change the line period from the standard 64 microseconds It is possible to calculate the line period for any speed As the track angle in C format is so small the error caused by assuming it is zero is of the order of 0 1 which can be neglected The line period in inversely proportional to the head tape speed At X1 forward the tape speed is 239 8mm s and the head to tape speed is 21 39m s If the tape is run at 2X normal speed the head tape speed will now 21 39 0 2398m s and the line period will be _ 64X2139 us 63 29 ps 2139 0 2398 a change of about 1 1 It is important to remember that although the line period becomes smaller the field rate remains constant owing to the consta
33. 519 QQvO2 6 QQvo3 10 QQvo7 50 QVO3 12 QY365 0 3 125 074 250 R1169 RG3 1250 RG3 250A RG4 1250 RG4 3000 RM 126 RR3 250 RR3 1250 SP41 SSR 13 7160 T2888HOG TB2 5 300 1 5 500 uus VLS631 VATS VRI5O 2 XG1 2500 XG2 500 XG2 6400 XG5 500 16004 XR1 3200 XR1 6400 v6028 28030 2010055 ZM1000 2M100 2M1020 OA2WA 2 QB82WA 1824 1835 1863A 18638 1P21 1 28 2AS 5A 2C39A 2C39WA 2021 2 26 2242 2255 2K25 3 4002 35002 3828 38524 38w2 3c23 3C45 3CX100A5 3CX1000A7 3 1500 7 465A 4 125A 42504 4 400A 4 4008 4 4006 4632 4 35 25 4CX250B 4CX350A 4CX350A AMP 38 62 58 21 48 00 39 40 2 80 7 50 95 11400 82 00 79 50 1500 300 3 00 2375 24 50 39 00 495 398 00 52 50 57 00 76 00 80 00 73 30 66 00 34 50 85 00 EIM 49 00 39 50 70 00 68 00 72 00 440 00 370 00 785 00 5 00 64 75 250 00 42 50 225 00 3 50 2 50 24 00 128 00 535 00 76 00 6 00 375 x ANANN NEW VALVES National Varian Mullard RCA ITT GAVE 6AWBA 28 6BA6 6BABA 6BE6 68 68 6 6816 6BL7GTA 6818 68M6 68M8 68N8 6805 6 68x6 6826 6 4 6 7 6 ecre 6co 6CH6 6CJ3 5646 6CL6 6CM5 6CN6 6006 6Cw5 8 5 6cv 6 25 6046 60C6 60C8
34. 1515 x 44 Front 10 As previously advertised 23 91 UK C P 2 10 TOROIDAL TRANSFORMER XN 100 watts isolations 230 240V AC plus 8 0 BV 4A 15 0 15V 0 6454 30V 0 16 size approx 415 dia x 1 6 91 UK 75p PRESTEL KIT Complete set of PRESTEL adaptor cards Con sisting of main processor card with battery backed RAM modem card direct tine coupler and keypad Outputs are composite monochrome and separate RGB Suitable for use with colour monitors or suitable TVs PS 12V and H ASCII KEYBOARDS _ Computer keyboards Ali models brand new QWERTY UK C P 1 00 All models 5V and 12V Amp P S 7 78 69505 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 26 04 SMK 68 Key general purpose steel plate Redefinable output Neg strobe pulse 4 user definable keys shift and control keys etc With connector 37 35 Olscounts for quantities please enquire Computer calc etc keyboard bargains for callers LWAYS KEYBOARO BARGAINS FOR CALLERS THERMAL PRINTER COMPLETE WITH FULL HANDBOOK 3 ROLLS PAPER 43 43 1 00 SUITABLE FOR TANOY ORIC NASCOM GEMINI ACORN NEW BRAIN ORAGON ETC ETC interface unit with leads 13 state modell your enquiries invited CHERRY KEY PAD 16 button key pad non encoded 5
35. 2201 1 50 OC203 3 00 ZTX502 0 18 2N1309 1 20 2N3772 1 60 application 0 90 _ 0 11 0 44 0 28 300 OAZ206 1 50 3 00 019 2N 613 0 32 2 3773 1 80 EF85 1 75 20 00 OD3 1 50 2 00 42504 8000 6CG7 2 50 12AX7 175 5642 9 00 VALVES 1 75 GXUI 1535 024 3 50 2986 vro 210 44004 8700 6CH6 1300 12AY7A 400 5654 3 00 EISOF 10 20 150 GXU2 30 00 86 150 Qvy42s0 6800 0280 1 m 4B32 2000 6CL6 3 75 12B4A 3 50 5651 4 45 1834 9 00 E182CC 13 25 EF91 2 95 GXU3 25 40 PC88 2 50 QY4 400 74 20 UF85 18 4035 78 00 6CWA4 8 00 12BA6 2 50 670 4 50 2087 13 50 11 50 EF92 637 GXU4 4450 95 175 Qys soo 175 00 UF89 2 4CX250B 45 00 602 150 12BE6 250 5675 28 00 A2134 17 50 EIS8RCC 8 91 EF93 1 50 GXUSO 20 00 PC97 1 75 QYS 3000A UL41 3 50 4CX350A 73 00 6DK6 3 0 12BH7 275 5687 6 00 A2293 16 00 E280F 2251 2 50 GY501 3 00 1 75 420 00 01 84 1 75 4 150 60 00 60068 475 12BY7 3 00 5696 4 50 2426 27 50 12 00 EF95 599 6232 4 00 1 50 0206 20 3270 UMS80 2 00 4 1500 56 00 6EA8 300 UEI 20 00 5718 7 50 A252 25 00 E288CC 17 50 EF98 2 0 6233 475 PCCSS 1 50 Rio 600 41 2 25 58254 35 00 6EBS 250 I2EMTT 28 00 5725 5 50 A2900 150 EAS2 32 25 EFI83 2 00 Gz34 3 00 PCC88 2 00 RI 3 00 UY85 2 25 5B255M 35 00 6EW6 225 1284 65 00 5726 1 37 3343 45 00 EA76 250 EFI84 2 00
36. 3 475 P P 744522 70 7415606 0800 200p LM13600 110p P 2651 12 07002 600p 8 0 175p 7442 75 741526 70p 7415610 200p 515131 230p 2030 250p 35332 5101 5501 450P 28 5860 175p 7444 120p 745527 70 7415612 06308 300 515161 500p 2541 400p 3245 asop 59516 1000 8131 325p 100 175 74452 1595 74LS28 70 7415626 350p 1366 190p 3712 200p 1043560 990p 5530 616723 850 04 300p 8032513 1050 250 7446A 120 740929 608 7415628 350p 1388 250 MB3730 400p 7000 350p 6222 3508 9116LP 3 950 053691 359p U C 750 1070 200p 7447 120p 300 CL7108 700p MC1310P 150p 061 50 552 2598 6264 15 35000 058830 140p 7098 110 2908 1 07611 95p 1413 130p P 058831 150 12 1 7450 74 592 60 143640 1280 17650 400p 1458 40 11064 6532 650 680 180p Dsge32 150p 66760 750p 140 150 7451 60b 74 83 100p 7415641 250p CL7660 250p MC1493 100p 1077 45 6221 200p 4745189 225p 058833 225p 14318 175 7453 60 eon 7415642 1300p CL8038 300 MC1495L 350p TLO72 60 68821 250p 745201 350 058836 150p 14756 250 7454 740949 1005 7415643 2505 1 72158 2400 MC1496 70 TLO74 25 145289 225 psggss 225p 15 0 200
37. Burnage Lane Manchester 061 431 4866 Space donated by WORLD CIRCLE 25 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com NEW PRODUCTS Communications 84 Birmingham Business communications seemed to be the central theme of the exhibition held at the NEC in Birmingham The integration of communications services usually thought of as separate entities was emphasized by several exhibitors the office computer terminal can also be a telex and teletex terminal and an autodial telephone as well as offering local computing word processing calendar and diary calculator station with optional extension fora secretary which offerred most of the same facilities and a built in intercom If you believe that electronics is communications then the exhibition has something to offer to anyone interested in electronics This is certainly confirmed by the variety of the products on show anything from a complete satellite receiver station to a single transistor and and directory One such device almost anything that can be launched by STC thought of that includes the Telecommunications was prefixes tele or trans Executel a multipurpose work from fumes or acid spillage VO C E Under normal operating RECOGNITION SYSTEM The facility for someone to speak to a computer and get it to obey has been appealing to the imagination for some time and
38. RADIOCODE CLOCK ATOMIC TIME FREQUENCY AND SYNCHRONISATION EQUIPMENT m AMATO ommo YE SOLVE PROBLEMS NEW PHASE MODULATION SYSTEMS Until recently atomic time and date information was only available v l f transmissions using amplitude modulation The RCC 8000AM series of 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 Watts to offer long range excellent noise immunity and no scheduled maintenance periods NEW PRODUCTS The AM and PM series of Radiocode Clock equipment has been further expanded to include seven new models from top 80005 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 puise Speaking clock time announcement or audio recording Slave controller total control of single standard master slave systems ie one pulse sec Dual standard slave controller total contro 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 operati
39. playback electronics A neat modem design is carried through the S Range of meters and instruments from Philip Harris They are designed with particular attention to reliability ease of servicing and user Safety and feature ease of storage and are clearly marked for identification The range includes a dual trace oscilloscope adaptor various power supply and amplifiers meters for joules conductivity pH counters timers and an electrical safety tester Philip Harris Ltd Lynne Lane Shenstone Staffs WS14 OEE WW270 A CNC lathe which can be controlled from a BBC micro is produced by Colne Robotics and described in a leaflet Included is the basic software which provides a comprehensive range of control codes to program and retain complex cutting sequences Safety measures are provided by hardware safety cut out switches and from within the software Robotics Co Ltd Beaufort Road off Richmond Road Twickenham Middlesex TW1 2PQ WW271 A range of small p c bs each with elements of a circuit can be linked together to make up more complex circuits This is the Alpha system from Unilab It is designed to bea low cost radical approach to the effective teaching and learning of basic electronics initially for the 13 age range There is also a range for more advanced work Details supplied in a leaflet from Unilab Clarendon Road Blackburn Lancs BB1 9TA WW272 WWW americanradiohistorv com
40. 075 MHLDG 400 32 00 0 090 1835A 2950 6ABB 0 66 624 110 2042 1050 5749 250 2 9485 E790 150 450 OQVO6 40A 037 900 10 250 200 6JAWA 315 2001 070 5750 185 DH79 0 56 F6064 2 95 MS4B 5 50 19 50 941 6 95 1C5GT 2 50 2 50 645 2 50 20LF6 3 50 5751 2 95 DH149 2 00 200 E FW4 800 2 95 150 00 07 50 050 2 00 105 2 50 6AF9 415 6 6 0 65 2011 0 95 5763 4 95 020 202 188 1 N37 12 50 63 50 082 3 00 1FD1 2 50 6AG5 6J86A 3 95 20P1 0 55 5814A 325 DK92 120 F80 08 2000 76 985 00703 20 us 020 16367 250 6AG7 6JEGC 4 95 2093 0 60 5840 350 250 600 Giao 2M 900 0 85 42 50 0192 100 0 60 6AH6 60566 4 95 20 4 195 5842 1100 01388 250 20780 1250 6240 20 900 OA2WA 150 OQZ0640A 0193 065 116 150 637 415 20P5 115 5894 39 50 prose 225 G400 1K 1400 OA3 250 45 25 025 100 Lae 100 6AJ7 200 6K7G 0 70 2408 250 5899 4550 DIJO ECHI 250 2750 082 0 85 0572 20 150 807 075 1 56 250 GAKS 100 6K8Y 3 95 2481 3950 5963 175 003 250 340 GCIOD 1750 OB2WA 125 0575 40 300 UABCBO 065 152 055 sake 200 6 6 550 25L6GT 175 5968 225 0191 180 215 1750 QC2 250 0592 10 5 00 UAFa2 100 174 070 GALS 060 611 250 25806 175 6005 1 85
41. 2 amp 6450 1 35 2 4 00 1 5ma 50ma 100ma 500ma 1 amp 2 amp 5 amp 25 PANEL METERS 100ua 500ua 1ma LOW VOLTAGE ELECTROLYTICS 500 12V 15 25V 20 50V 30 1200mF 76V 80 1000mF 12V 20p 25V 35p 50V 50p 100 1 20 RCS SOUND TO LIGHT CONTROL BOX 3 channel 1000 watt each For home hi fi or disco Stabilised safety cutout 5x 3Vax 2 2 5 Post 1 59x53x34mm Stereo VU 82 41 25 5 p p 50 2000mF 30V 42p 40V 60p 100V 1 40 1500mF 100V 1 20 2500mF 50V 70p 3000mF 50V 65p 4700mF 40V 1 CAPACITORS WIRE END High Voltage Complete ready to use with cabinet size 9x 3x 5in 27 001 002 003 005 01 02 03 05 mfd 400V 10 1MF 400V 14 600V 15 1000V 25 OR KIT OF PARTS 19 50 Post 1 22MF 350V 12p 600V 20p 1000V 30p 1750V 60p BATTERY ELIMINATOR Mains to 9 volt D C 400MA 47MF 150V 10p 400V 25p 630V 30p HIGH VOLTAGE ELECTROLYTICS 2 500 45 32 32 16 350V 90 8 16 4507 95 DISCO GRAPHIC MIXER EQUALISER 112 Post 2 display headphone monitor Deluxe Model 5 channel 7 band graphic 128 RADIO COMPONENT SPECIALISTS 16 450 50 100 100 275V 50 16 16 350V 80 20 500V 75 150 200 275 50 32 32 350V 85 4 channel stereo 5 band graphic red green LED VU 32 350V 45 32 32 32 450V 95 20 20 350 75 32 500V 95 47 350 50 50 300 50 125 500 42 8 8 500V 50 50 350V
42. 2100 27 92000 a0 Taco withpsu Teac 300 002 FORTH with Manuals Pleaseadd carriase 50 nless indicated as foli 10 00d 5200K 40 80 Track with psuTeac 400 00 Full Range ease camage gt SS Indica as S T a 8 b c 1 50 d 1 00 BBC FIRMWARE 2x400K 80 Track DS with psu Mitsu 420 00a PRORAM POWER Full Range a 1 2 Operating System 7 50d 3 Hitachi 100K Drive 150 00c BEEBUGSOFT Full Range TORCH Z80 DISC PACK The proven upgrade for the BBC Micro Comprising 2 X 400K disc drive Z80 processor with 64K of memory and a CP M compatible operating system it opens up the vast range of CP M software includ ing advance languages scientific and business applications The sys tem is supplied with the PERFECT software range including PERFECT WRITER PERFECT SPELLER PERFECT CALC and PERFECT FILE Full TORCHNET software is also supplied allowing sophisticated networking between other units This wili allow access to information and communication between up to 254 suitably upgraded BBCs NEW TORCH Z80 PACK PRICE 699 SOFTWARE PACKAGE INCLUDES Z80 BASIC Phone for details about the 20Mbyte Hard Disc Pack and the 68000 Hard Disc Pack with UNIX Operating System NOW AVAILABLE The TORCH 280 SECOND PROCESSOR CARD for those who already have suitable disc drives The card is supplied with all th free perfect software and Z80 basic as detailed
43. 24 steps per rev oy 15 oz in torque 100PPS Body pads 2 8 WINCHESTER SHUGART DRIVES ALL PRICES NOW INCLUDE VAT CARRIAGE 2E ACH YOO OR PoC CCC CSCC SY diameter 2 shaft Va diam x 4 4 spirally UNITED PERIPHERALS model 3100 Mini threaded disc drives 3 X 8 sealed plattens cap 8 Shugart type SA800 Floppy disc drives Bop dec Weight Jor Piee each EIS p amp p able of over 19MBytes storage External Small quantity available single sided up CENTRIFUGAL BLOWERS penea d power supply requirements are 24V 3A to 800KBytes of storage Power require TORIN Type U62B1 230V Cap Start supplied and 5V 6 4A Little used condition ments 5V 13A Little used excellent very powerful 200W 3 000rpm centrifugal fans TELEVISION SERVICE KIT believed OK but at the unbelievable price condition PRICE 90 inclusive VAT and for large rack cooling or enclosure extraction appli We have managed to oblain a stock of Labgear T V Service of just 125 are sold without guarantee Carriage and copy of user handbook cations Overall dimensions 20x12 cms outlet 6x4 equipment affording vast savings on new price All items are Price inclusive of VAT and carriage J cms BRAND NEW Surplus stock 15 each inc sold full working condition and guaranteed Copy of user handbook VAT pp 1 50 LABGEAR CM6037 DB UHF VHF PAL COLOUR BARGEN e
44. 27 256 7 1772716 2732 2764 27128 27256 2516 27512 2532 ee This outstanding new range of British made EPROM Among the many other features of the GP P9000 Programmers are as fast and efficient as they look normally only obtained from far more expensive Everything about them is designed for high speed device programmers are menu selection of devices label handling selected algorithms can reduce programming printing as standard powerful editing facilities 5232 time by up to 90 and they re skilfully designed for port with baud rates up to 19 2K baud and 12 different accurate and easy operation transfer formats plus comprehensive fail safe checking The P9000 range is available in 3 different medels all for device and machine protection of them program a wide range of EPROMs richt up to the Let GP bring you fully up to date with your programming new 64K x 8 devices and no personality cards or telephone for a colour brochure Now modules are needed MK2716 TMS2508 R5213 TMM323 HN462716 MSL271 TMS 2716 R87C32 TMM2732 HN48016 5 273 TMS2516 2764 HN462532 MSL27 52532 ET2716 TMM27128 HN462732 152732 2716 HN482732 TMS2564 ET2732 HN482764 2716 52764 2764 5 HN27C64 NMC27C 16 GP Industrial Electronics Ltd 716 Unit Huxley Close Newnham Industrial Estate Plympton Plymouth PL7 4JN NMC2532 2816 Teleph
45. 60J8 6075 60w48 6 5 6EHS 6 58 6EV7 6Ew6 6FG6 6FHS 6 55 6685 66 5 66 5 6GHBA 66 5 66 7 6GK6 Gwa 6Gx6 6676 6H6 6HA6 6HB6 6HES 6HF5 6HGS 6 6HS6 6HZ6 635 6J5GT 6 6 6 6 6 85 6J86A 6JC6A 6JE6C 6JG6A BJHB 6JK6 6JM6 6256 6K6GT 6K8 6K11 6K06 6K08 6KEB 6K66 5 6KNB 6KXB 6L6GC 666 244 SLNE 6 06 6MI1 6MJ6 6011 6SA7 8SL7GT 6SN7GTB 6SAT 6u4 6UBA 6 4 6V6GT 6X5GT 6 ovo TF 8 7 9SP4 12 6 12AT7 17406 12 12 6 METAL AN FUN gt ESL OEUNNUNUN NUN 39 49 72 7815AL GE 7TB SRAL 7868 7903 7905 7984 8008 8020 8032 8056 5058 8072 8117 8121 8122 8153 8164 8233 8278 82984 8321 EIM 8321 AMP 8416 8417 8422 8438 8552 8553 8608 8643 8754 8794 8874 8906AL 8908 8950 9001 9844A 9950 16411 ELECTRO OPTICAL DEVICES 20PE11 20 14 20 15 20PE19 20PE20 XQ1275 xQ1276 4848 72624 7735 8541 8843 9677 Other types of Vidicon availabie Newviconsand U tracons price on sppilcation Telephone 0376 27117 24 hour Ansaphone Service Telex Hay Lane Braintree 42494 987911 Essex CM7 6ST DISTRIBUTOR
46. 74LS243 M0p 745573 500 MCT26 100p 11112 80731 75p MPF102 40 ZTX504 22 2N5459 30p 600 30p 34600 180b 7415244 300p MCS2400 19 p 110113 70 0132 80 MPF103 4 40 ZTX552 5 2N5460 80p 2 50V 30 12A400V 1605 7415245 350 MOC3020 156 10116 70 80135 6 40 105 40 ZTX652 0 2N5485 36 2A 100V 35p ic 100v 1805 7415247 120 4000 30 1074 180p 64137 400p 0139 40 MPSA06 ZTX752 70 2N5875 250p 2A 400V 45 16A 400V 2205 74 5248 120p 4001 30p FND357 120p cop MPSA 2 50 2N697 35p 2N5883 2007 60 455 7418249 120 4002 4425 9 50 24698 45 2 6027 30 600V 72 36p 7415251 100 4006 0p TE 74 140p 80232 MPSA20 50 2N706A 36 2N6052 100V 95p 243525 130p 7415253 100 4007 30p TIL209 Red 10 4640 200p BD233 75 MPSA42 50 2N708 36p 2N6059 4A 400v 100p 544444 180 74 S256 200p 4008 305 11209 89d 192 MAN8S10 25 80235 85 MPSA43 50 2 918 45 2 6107 50 545060 309 74LS257A 120p 4009 11212 Ye isp TIC729 140p BD241 60 MPSA56 30 23930 30p 2N6247 100V 100p 325 74L8258A 100p 4010 2 el 152 16730 140 80222 0 5 70 50 2N 31 2 SOp 22N6254 400V 120p 2200 358 74LS259 4011 30p 0 2 NSB5881 570p 80379 60
47. 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 the 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 ALHA Recruitment Office Government Communications Headquarters Oakley Priors Road Cheltenham Gloucestershire GL52 2452 ARTICLES FOR SALE PERFECTION ASSURED FL
48. American Express card no 3 2 _ date J Saffron Walden Essex CB11 3AQ FOR IMMEDIATE ACTION The S C 24 hour 5 day a week service For Free Telephone 0799 21682 and give us your Barclaycard Access American catalogue Telephone Saffron Walden 0799 21682 Express number and your arder wil be in the post immediately uck box JS 1 gt _ NEC d 1 817477 CIRCLE 26 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 21 WWW americanradiohistorv com by Adelson Ronald Adelson graduated in enum ieering from Cambridge niversity in 1956 Aftera spell in industrial electronics he entered the field of opera tional research which has been his principal occupation since However he has kept up an active interest in electron ics especially where it impinges on his interests as a musician actually he plays the bassoon perhaps not quite the same thing He joined the Operational Research Department of Lan caster University in 1967 A recent initiative by the Music Department at Lancaster is currently enabling him to spend some of his time putting his technical skills to work Fig 2 Circuit of the music keyboard interface Whenever strobe voltage goes outside the narrow window defined by dual comparator IC generates an interrupt at CB The computer then responds by reading the inputs of IC then Weeds them on using CB on
49. Beware of 1200 75 systems some use the same data format as on their 300 baud modems and may not be compatible with Pres tel terminal software CBBS Chiltern 07073 28723 07073 39241 18 30 22 30h Mon day and Wednesday CBBS Cumbria 069 92314 1800 Fig 3 Disabling RTS and DTR during the auto answer sequ is addition has been incorporated in the p c b for ence this project 2200h daily V 21 Bell 103 and 1200 75 baud V 23 CBBS Southwest 0626 890014 24 hours V 21 and 1200 75 baud V 23 CBBS Surrey Woking 04862 25174 24 hours MG NET CBBS London 01 399 2136 Sunday only 17 00 22 00h CABB Computer Answers bulletin board London 01 631 3076 24 hours Also weekdays on 1200 75 baud V 23 Forum 80 Hull 0482 859169 Tuesday and Thursday 19 00 22 00h Saturday and Sunday 13 00 22 00h Night time service for U S A using Bell 103 tones 00 00 08 00h Forum 80 London 01 902 2546 evenings and weekends Mailbox 80 Liverpool 051 428 8924 24 hours Mailbox 83 West Midlands 0384 635336 17 30 08 30h daily and all day Sunday Manchester BB 061 427 3711 Sunday Thursday 22 30 00 0h Fri day 13 30 02 00h Saturday 22 30 02 00h Microweb Stockport 061 456 4157 24 hours For users of the BBC Micro TBBS City London 01 606 4194 24 hours 1200 75 on Wednesdays TBBS London 01 348 400 09 00 01 00h with CCITT V 21 tones ELECTRONICS amp WIRELESS WORLD JULY 1
50. D63 120 ECC35 350 3 25 27800 0 79 25 2759 19 85 215 666 2 00 12K7GT 0 60 1619 2 50 230 15 750 07 78000 3 00 5 8 1220 6 12 150 12 8 110 1625 300 DA42 7 5 225 85 395 8096 30 0113 1108 90 78030 1895 5AR4 200 6F13 3 00 1207GT 0 50 1626 3 00 DA100 125 00 ECC82 Philips 47 50 TD03 10F 241000 1250 150 1 00 12SA7GT 1 00 2050W 450 0 70 1 50 10 800 8099 500 083 300 30 50 28 00 2 1001 150 5 110 10 00 17 2 75 12567 475 2050 2 75 DAFS6 0 65 065 EN32 1350 8100 550 QE0310 3 50 TD3 12 400 ZA1002 150 58 254 1450 6F21 2 50 12SH7 100 3545 400 00 125 140 8136 700 0 08 200 150 Zc1040 800 58 255 1950 6F22 070 12567 100 4313 400 BESO panteoi Mullard 135 2450 5 50 145 00 700 2 1005 58256 900 6F23 060 125J7 060 43286 900 DCX4 1000 ECC83 Philips ESU872 25 00 MB161 650 40 65 00 TT 150 7 1020 8 95 5B 257M 9 00 6 24 1 25 125 76 185 5642 9 50 12 00 1 95 EYS 080 8162 550 25 100 TTi5 3495 2 1021 800 58 258 14 50 6F25 125 12SQ7GT 1 50 5651 2 50 6000 050 tva 50 8163 550 03 12 6 50 TY2 125A60 00 2 1023 7 95 5C22 6900 6F28 125 1303 320 5654 1 95 2500 ECC85 060
51. For ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com certain other sets r f modules giving coverage of additional bands are available as an acces sory Tx power the transmitter power quoted by the manufacturer nor mally for the f m mode Two figures separated by an oblique stroke indicate high and low power settings The separator gt indicates that the power is continuously variable between the limits shown Syn xtal s denotes frequency synthesiser tuning x denotes a crystal oscillator providing only those channels for which suitable crystals have been fitted F m step the normal minimum tuning step in n b f m use Some multi mode sets are capable of much smaller steps even on f m In many cases thesize of the step is programmable for example 12 5 and 25kHz can be selected instead of 5 and 10kHz if the user wishes Tuning method d indicates a conventional knob or dial thumbw indicates thumbwheel Switches and u d indicates up down buttons Memories most present day sets permit storage and instant selection of a number of the user s favourite frequencies Certain models also have one or more variable frequency oscillators which can be used as additional memories Scan modes some sets allow scanning of frequencies stored in memory m others provide scanning of the entire band b or programmable sectors of it S meter most s
52. GZ37 475 PCCE 1 75 8 3 00 VLS631 15 00 5C22 160 00 6F6 3 00 170 00 5727 7 05 231 2 75 EABC80 1 25 8045 12 00 KT61 5 00 PCCIS9 2 50 R19 9 24 XG1 2500 55 00 SJ180E 1650 00 6F23 1 60 19H4 27 50 5749 2 50 241 2 60 91 3 50 8055 15 00 KT66 12 00 05 1 60 R20 2 50 XG2 6400 SRAGY 3 50 6F28 1 60 19 5 47 50 5751 4 00 448 114 90 EAF42 2 50 90 1 75 KT77 Gold Lion PCC806 1 60 RG3 250 32 68 141 90 5046 3 00 6F33 33 50 2489 67 25 5763 4 50 BK484 15535 EAF801 2 00 EK90 1 50 9 00 PCES2 2 00 RG3 250A 3268 XG5 500 26 60 SU4GB 2 50 6 14 00 30 15 20 5814A 4 00 8590 58 00 4 00 EL32 150 KT88 15 00 PCF80 2 00 RG3 1250 59 50 XG2 6400 5V4G 2 50 6H2N 275 30 17 100 5840 4 00 BS810 60 00 9 150 EL33 4 00 KTW61 2 50 PCF82 1 50 RG4 1250 61 60 162 00 SY3GT 2 50 6H3N 2 75 30 18 2 09 5842 12 00 5 58 95 EBC33 2 50 EL34MUI 400 KTW62 2 50 PCF86 2 50 RG4 3000 99 45 XRI 1600A 523 4 00 6H6 3 0 3065 1 60 58764 31 50 7 151 00 EBC4 2 50 EL36 150 KTW63 2 50 PCF87 2 00 RR3250 40 00 53 75 5246 150 61 5 50 30FL1 2 138 5879 5 00 BTI9 44 05 1 50 EL41 2 80 M8079 12 34 PCF200 3 25 RR3 1250 45 75 XR1 3200 81 97 5Z4GT 2 50 66 8 93 30FLI2 180 5886 15 00 BT29 349 15 0 1 25 EL42 2 50 M8080 8 25 201 3 25 SIIEI2 65 00 XRI1 3200A 63012 1 75 647 475 30114 2 00 5963 2 50 35480 0 1 50
53. IN4003 0 06 22221 0 20 2N4058 0 20 0 55 AUYIO 300 BCI84 011 2 00 BFS l 0 20 MJES2 0 73 OC28 2 00 TIC44 027 IN4004 007 2N2222 0 20 2 4059 0 20 ACI25 0 25 BAI45 0 13 011 1 20 BFS98 0 20 2955 1 30 OC29 2 00 TIC226D 1 20 IN4005 0 09 2N2223 4 25 2N4060 016 ACIJ6 025 015 011 BFWIO 097 MJEXSS 110 OGS 1 50 016 Noe oii 0725 DUET ACI27 0 25 0 10 BC214 011 BD2137 0 54 0 96 MPF102 0 35 OC36 1 50 TIP29A 0 43 1 407 0 12 2N2369A 0 25 2N4062 016 ACI28 030 BAISS 011 237 011 gp2zsg 0 54 BFX84 030 0 35 0 90 TIP30A 0 45 194009 0 07 2N2484 0 25 2N414 016 141 0 28 030 238 011 0 9 8 0 30 0 35 OC42 0 90 TIP3IA 0 33 1 448 0 04 2N2646 0 50 734126 016 0 35 BAW62 0 05 BC301 0 33 2 00 BFX87 0 30 MPFI05 0 35 1 50 TIP32A 0 36 135400 013 22904 0 32 244286 015 ACI42 0 28 BAXI3 0 6 BC33 0 34 1 50 BFX88 0 30 MPSA 0 26 0 85 TIP33A 0 54 145401 0 13 292905 0 32 2N428 018 0 35 6 0 06 BC37 011 2 75 BFYSO 0 25 MPSAS6 0 28 45 0 65 TIP34A 0 67 1544 0 04 242906 0 21 24289 0 18 ACI76 0 30 07 0 16 308 0 1 5 0 35 BFYS 0 25 001 0 53 0 55 TIP4IA 0 44 15920 0
54. Telequipment Oscilloscope Type S32A DC to 3MHz Airmec Millivolt Meter Type301A Advance Audio Generator Type H1 Bruel 8 Kjoer Microphone Amplifier Type2604 AirmecSweep Signal Generator Type 352 20 Hz to 200 KHz Bellx Variable Power UnitO to 50V 212 BTR Silvertown Anti Static and Conductive Footwear Tester Dawe True AMS Valve Voltmeter 612 Tektronix Time Mark Generator Type 180A PYE POCKETFONE PF1 EDDYSTONE RECEIVERS RADIOSONDE RS21 UHF RECEIVER 440 470 MHz Single Channel int speaker and aerial Supplied complete with rechargeable battery and service manual 6 each pius 1 p p plus V A T Model 770R 120 each TRANSMITTER Airmec Modulation Meter Type 409 120 Servomex AC Voltage Stabiliser Type AC2 240 vac 9amp 45 Servomex AC Voltage Stabiliser Type 7 240 vac 40amp 95 Hewlett Packard Sweep Generator 6920 1 8 4 2Ghz 300 Tektronix Storage Display Unit Type 611 120 Tektronix Oscilloscope Type 515A 85 Tektronix Plugin Type CA 25 Schomandl Frequency Meter Type FD130 900Mhz 50 Rohde amp Schwarz AF Wave Analyzer BN48302 50 Rohde amp Schwarz UHF Test Receiver Type BN1523 280 940Mhz 75 Airmec Modulation Meter Type 210 3 300M hz 95 Marconi Carrier Deviation Meter TF 7910 4 1024Mhz 125 Marconi FM Signal Generator TF 1066B 1 10 470Mhz 280 Marconi AM Signal Generator Type TF 144H 4S 10Khz 72Mhz 125 Marconi Qut of Limits Indicalor Type TF 2404 60
55. above presenting a very attractive package 299 Torch 2 0 240 Mbyte Hard Disc 400K Flopy 1995 ACORN IEEE INTERFACE A full implementation of the IEEE 488 standard provid ing computer control of compatible scientific amp technical equipment at a lower price than other systems Typical applications are in experimental work in academic and industrial laboratories The interface can support a network of upto 14 other compatible devices and would typically link several items of test equipment allowing them to run with the optimum of efficiency The IEEE Fil ing System ROM is supplied 282 BUZZ BOX full spec pocket size direct connect modem with both Originate and Answer modes this BT approved modem conforms to CCITT V21 300 300 Baud Standard Battery Mains powered plugs directly into telephone line Modem 269 head 23 50 Ext PSU 28 00 BOOKS We have a large selection of books on the BBC and other titles Please ask for details No VAT on books TIME WARP REAL TIME CLOCK CALENDAR A low cost unit that opens up the total range of Real Time applications With its full battery backup possibilities include an Electronic Diary continuous display of on screen time and date information automatic document dat ing precise timing amp control in scientific applic ations recreational use in games etc its uses endless and are simply limited by one s imagination Simply plugs into
56. amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com 5422 5232 converter RS422 is a half duplex data link standard and being balanced allows greater distances to be covered and higher data rates than are possible using RS232 It can also be used with one transmitter and several receivers multi drop This circuit provides RS422 and line monitoring using an RS232 v d u or computer Normally the circuit is in receive mode and the v d u monitors the line When a key is pressed line four on the RS232 interface is inverted and the 75176 transmits the character Receive mode is resumed on key release Line five provides information on the direction of the line and may be omitted Essentially the circuit is a level converter and therefore independent of data rates Note that direction reversal time on an RS422 line can be far shorter than that of a simple v d u CIRCUIT IDEAS 75176 1489 require only 5V Gnd 1488 also requires 12V 12V which can lead to apparent loss of characters twisted pair should be used for the 422 line as the 75176 is very sensitive and care RS422 in out Aout Dout Ain Bout 1089 5232 to vdu should be taken with layout L Smith Blackford Perthshire DON T WASTE GOOD IDEAS We prefer circuit ideas with neat drawings and widely spaced typescripts but we would rather have scribbles on the back of an envelope than let good idea
57. and describe the type of of working environment most suited to your career plans The Recruitment Officer HMGCC Hanslope Park Buckinghamshire MK19 7BH 2448 WWW americanracdiohistorv com At Government Communications Centre we re using the very latest ideas in electronics technology to 95 Appointments This is an opportunity to join a team which provides vocational training for technical staff in the operation and maintenance of telecommunication equipment for Police Forces and Fire Brigades in England and Wales and for the Home Defence and Prison Services You will identify staff training requirements develop new training techniques approve applications for academic training operate to a financial budget prepare estimates provide statistical reports and cost data on Directorate of Telecommunications training and serve as Training Liaison Officer Candidates should have an appropriate degree or equivalent including overseas qualification in electronics or be suitably qualified senior technicians who have appropriate training and about 15 years experience in a related field of work and who have either satisfied the requirements for registration as Technician Engineer or hold an HNC FTC Electronics or Telecommunications Applicants should preferably be corporate members of a relevant professional institution All candidates should have at least 4 years experience in the design inst
58. carry pulse is used to provide a clocking and or loading signal throughout the logic outside the controller Synchronization is extremely important s one can see from the timing diagram there are many delays between the rising edge of the character clock initiat ing the addressing sequence and the production of a dot pattern at the output of the character gener ator and between this point and the coming of those dots and con trol signals for display blanking etc from the controller The timing diagram is to scale and incorporates the worst case delays specified for the i cs Two signals used to synchronize the system are rising edges of dot clock and carry signal To cope with delays between the con troller generating an M line add ress and the output of v d u memory settling a process which might take up to two thirds of a character period memory Continued on page 64 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWww americanradiohistorv com
59. daunting setting up procedure Recently both Signal Tech nology and Mullard have been manufacturing some excellent surface acoustic wave i f filters The SD155 from signal Technol is flat at frequencies above f and has a sound shelf of 1648 though probably not sufficiently down for a single chip demodula tor e g TDA 3541 though an LC trap to provide an extra 1048 could readily be added Over the retailers counter this could cost 40 to 50 currently but it is hoped that cable head companies and set manufacturers will start to use these better quality filters and the price will reduce Some of the better filters for example Signal Technology s SY 155 and RW 153P have the sub carrier equivalent frequency vi sion carrier minus subcarrier 35 07mHz only 0 5 to 2dB down These will provide the best overall performance with modi fied LC filters used before the chroma decoder However the performance is not good enough to justify the Fig 34 comb filter circuit approach although a much improved picture can be obtained with the alternative LC networks shown last month This 15 achieved by using the Fig 77 cir cuit for the luminance path Figs 74 and 76 show amplitude and group delay performance and the Fig 81 circuit for the chroma path Figs 79 and 80 give ampli tude and delay performance The chroma circuit can be modified to advantage as shown in Fig 93 See Figs 94 and 95 for amplitude and del
60. form of the popular 6845 v d u controller Its advantage to the computer designer is flexibility virtually all design parameters e g characters per line lines per screen sync pulse length etc being stored in registers loaded by the c p u rather than being fixed In the Hitatchi version capabilities of these registers are extended these capabilities are used in this design so it is import ant to use the specified device While it can be used for graphic displays its primary intent is as a character display controller and to this end it has control lines which can be fed to a character generator a rom which produces Dot data CRT controller HSYNC VSYNC Video dot patterns corresponding to characters placed in the v d u memory and skewed video con trol lines i e signals which can be delayed internally by one or two characters periods to allow a technique called pipelining to be used Pipelining is a technique used in complex v d us whereby v d u memory and character gene rator outputs are latched in sync hronism with the character display rate Whatever the speed of memory accesses providing they are each shorter than one charac ter display period 500ns in this system data passes or is piped synchronously through the v d u Being able to skew the display and cursor enabling sys tems means that it is easier to ensure that control and data informatio
61. from Logica has been enhanced by the introduction of a highly flexible multiplexer Polyline to interface computers with the network The device may be used with any computer or peripheral device with an RS232 port to give it access to the network which may also be used with high speed computer to computer traffic Polyline may be used to connect normally incompatible networked or stand alone devices In addition the multiplexer may be used to interface a terminal with external services such as electronic mail which may be available to the A microphone switch combination that allows hand free operation of a transceiver has many uses The Sonic Tornado voice operated switch is such a device and uses a inertial throat microphone or noise cancelling microphone The unit can be used with ear hanger headsets or be fitted into breathing masks and helmets Field trials have established that the sets will aane aeae ae a a a a m ea a www americanradiohistorv com TH DATA MULTIPLEXER host computer Each multiplexer can support up to eight asynchronous channels which operate full duplex and support communications over the network for six signal lines Control of the network can be undertaken by a Terminal Manager software package The Polynet Polyline combination can be used to provide high speed links between a number of otherwise incompatible mini and microcomputers from different manufacturers Logica VTS Ltd
62. knowing nothing about complex ones Ifa new theory along these lines is ever formulated and accepted it will be because it works better than the one it replaces E R R Holmberg Barnes London SW 13 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com The heavy duty versions of the Avo 1000 Series have to pass a lot of tests that aren t electrical Under normal operating conditions you can depend on the Avo 1000 Series to give long and reliable performance However we appreciate that a lot of users subject their test instruments to treatment that is far from normal They drop them into their toolkits throw pliers onto them or take them into hot and sticky boiler rooms So to make a tough range of instruments even tougher we have developed a special rubberised coating which is moulded directly onto the casing We put all our instruments through a series of tests that make normal rough treatment look like delicate handling We flash test them we subject them to intense vibration bump them up and down for hours make them sit in difficult climatic conditions and drop a heavy metal rod on them froma substantial height All this apart from the routine electrical tests they have to pass So if you want quality analogue multimeters that can take a lot of stick and continue to give accurate performance ask about the HD db 9935 row r1 APT I versions of the Avo 1000 Series at your
63. m CIRCLE 204 FOR FURTHER DETAILS PRICE 806 pus vaT 90 days warranty refund if not satisfied COLOUR oi 14 med resolution 190 extra Foundrometers Ltd South Accommodation Road Leeds 159 8LW Instrument makers estd 1919 Tel 0532 485811 Ask for David Brooke Telex 556408 EMERGENCY i7 STANDBY SYSTEM aL Comprising S 23 Floor Standing Steel Cabinet EQUIPMENT Constant Voltage RERO RIT Battery Charger Inverter _ _ Automatic Change plc TRICKLE AC MAINS CHARGER Voltmeter A wide range of Inverters 30 to 1000 Watts are available for incorpor ation in these Standby Systems They are the T type square wave or the 5 type sine wave having either 12v or 24 DC Input supply Recommended batteries not supplied for 200 watt Standby Sys tems 4 6 120AH each series parallel connected to a total capacity of 12v 240AH We also manufacture Frequency Changers AC DC Power Supplies No Break Systems and we are always happy to quote for your special requirements Please send for full details to Valnadio POWER LIMITED AK INTERNATIONAL BUILDING LAWRENCE ESTATE GREEN LANE HOUNSLOW MIDDX TW4 600 ENGLAND Tel 01 570 5622 WWW americanradiohistorv com CK1907 CK5687WA reatech up lectronics DISPLAY amp COMMUNICATION PRODUCTS NT2 PCLBOS PLSOS
64. pulse timers and Z80 interrupts Four mos timer lines are available for timing and sound gen eration A set of three Eurocard format plated through hole boards for SC84 is available from Combe Martin Electron ics King Street Combe Mar tin Devon EX4 OAD Price is 39 for the setincluding v a t and inland or overseas post age John Hodson secre tary of the Scientific Compu ter User Group is organiz ing the SC84 user group For further information send an 5 to him at 12 Broughton Road Basford Newcastle under Lyme new address A listing of SC84 s machine code operating system MCOS can be obtained by sending an s a e to Electron ics and Wireless World Room 1303 Quadrant House Quadrant Sutton Surrey SM2 5AS 65 SPECIAL FEATURE Table 1 Nominal allocations of Z80 i o ports Keyboard and parallel i o interfacing Port address hex Allocaton 0 0 3 0 4 7 0 8 0 9 Keyboard input and contro port output General purpose parallel i o Disc controller command and status port Keyboard requirement is for a source of seven bit ascii code with a positive going level strobe i e one which stays high as long as a particular key is pressed cir cuit shown last month As ascii is a seven bit code the eighth input bit is not wasted but used as a flag that the RS232C port is to echo v d u program output when using MCOS Not all keyboards have an auto repeat fu
65. several hundred miles A successful meeting of Dutch amateurs interested in narrow band mechanical television was held last March in Eindhoven attracting 50 to 60 visitors Historic 30 line equipment was displayed by Kees Sanders PAoDXY A camera monitor by P Wakker was made from small lenses taken from a broken road sign and driven by a bicyle dynamo Several British NBTV enthusiasts have been using silicon solar cells as pick up devices for low definition ELECTRONICS amp WIRELESS WORLD JULY 1984 systems A 96 mile mechanical system being developed by J A Short uses the old Baird techniques of obtaining sync signals by blanking off part of the picture i e no blacker than black pulses but uses a much more sophisticated form of sync separator discriminator Apparently it works which is more than could always be said of the Baird phonic wheel technique Wayne Green W2NSD editor of 73 Magazine in a petition for rule making submitted to the FCC has proposed that all American radio amateurs should be re examined for morse proficiency every two years with arequirement that they achieve a five word per minute up grading each time to a finallevel of 35 word min Failure to improve speed he suggests should result inloss of licence However it seems highly unlikely that FCC will impose such a rule Region 1 Conference At the 1984 IARU Region 1 Conference held at Cefalu Sicily DrJohn Allaway G3FKM was
66. this corresponds to an ambient of about 95 C Analog Devices Military CMOS parts are spec d at an AMBIENT of 125 C AN ALO For further information contact Analog Devices Limited Central Avenue DEVICES East Molesey Surrey KT8 OSN Tel 01 941 0466 Telex 929962 CIRCLE 35 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 53 WWW americanradiohistorv com GENERATORS NEW 501 FUNCTION GENERATOR 005Hz to 5MHz sine square triangle ramp pulse and haverwave waveforms free run triggered or gated modes variable start stop phase 19 1 symmetry range variable DC offset variable 500 output TTL output external sweep mode NEW 2502 SWEEP FUNCTION GENERATOR Main generator features as TG501 plus internal sweep generator 1000 1 linear or 10 000 1 log sweep range precise dial and enter setting of sweep limits marker with variable duration and out of range indicator variable sweep rate single Sweep mode sweep reset and hold sweep and pen lift outputs NEW 1G503 PULSE FUNCTION GENERATOR Main generator features as TG501 plus normal double and delayed pulse modes pulse width variable from 50ns to 50ms delay variable from 100ns to 50ms 10MHz capability in double pulse mode complement mode symmetrical positive going or negative going outputs with adjustable baseline For further information contact Thandar Electronics Ltd London Road St 5 Huntingdon Cambridgeshire PE17 4HJ Telephone 04
67. xi 6 90 x10 45 00 65 00 8 26 VARIABLE POWER SUPPLIES Ls 220 240V AC input gi qe PP241 single meter A V switch 0 30V amp 30 43 2433 amp version 52 13 230N Twin meter 0 30V 91 00 3308 3 amp version 164 00 UK C P above models 1 00 PL Laboratory series LED readout QMO versions series parallel etc PL31030V 118 00 13100 0 249 00 PL32030V2A 145 00 320 0 0 315 00 UK C P above models 2 50 ANALOGUE MULTIMETERS General range mirror scale UK 65p HC6015 15 range pocket 10K Volt 1 meg ohm 7 M200 30 range 20K Volt 20 87 Special purchase 8 65 list price 19 00 10287 22 range 20K Vait 10A OC plus cont Buzzer 10 Meg ohm 11 74 TMK500 23 range bench 30K Volt 12A OC Plus cont buzzer 20 Meg ohm 20 83 WHSGR 22 range 10K Voit 6 Mag ohm 10 39 8 x 26 range 30K Volt 10 0 10 Meg ohm 20 83 3 23 range bench jr es large scalo 10A AC OC pius Hfe tester 10 34 74 AT2100 31 range de luxe 100 10 0 100 29 13 1020 18 range de luxe 20K Volt plus taster 5 Meg ohm 18 YN3GOTR 19 rangs 20K Vel plus Hie tester 1 Meg ohm 12 13 KR 1 Range doubler 35 range total 50K Volt 10A 0 20 Mag ohm 17 35 ST303TR 22 range 20K Voli ptus H s tester 12A DC 1 Meg ohm 15 61 ELECTRONIC INSULATION TESTER 500V 0 100 Meg o
68. 0092 995 100 1750 150 0595 10 485 UBFB0 060 105 100 325 6119 395 2901 1950 6012 1600 Duss 078 GCI2 AB 1750 063 170 05108 45 400 08 41 2 95 1 28 140 6AMS 600 6L6GC 295 30C17 040 6021 3 65 Disa 250 048 6088 600 00 05150 15 695 150 287 150 150 6L6GC GE 3 95 30C18 148 6057 250 0696 1250 ECH2000 150 607120 5 00 OMSB 3 00 05150 30 115 UBF89 060 2621 100 265 6667 115 30F5 0 95 6059 3 75 01516 10 00 80 060 GE10 9 00 OM6 1 75 QS150 45 7 00 UBL21 1 75 2C39A H 2 65 6176 0 75 30FLY 1 00 6060 2 25 DM70 1 ECL2 065 Gio 180 395 OSUO2 3 dzo 04S ereo aso 0 c 450 4 GNIO 15 00 95 295 UCCB4 0 70 0 85 5 6063 200 0160 275 2083 289 GRIOG 400 250 051203 415 5 060 3 95 6006 495 30FLI3 110 6064 3 25 Baie oa mms 1 10 16 50 UCH21 1 20 72 4 20 DY802 0272 Ecles oes GSIOH 1200 2686 075 051207 090 120 450 6215 150 30015 0 60 6080 475 995 EFSA 200 65120 1200 88 075 051208 0 90 42 135 0 75 6 25 4 00 30017 0 60 6080WA 850 JEU T en 799 GTC 140 PC92 350 051209 200 065 175 6P28 200 30PAMR 100 6096 285 E80 350 6116 5 5 13 00 PC97 1 10 051210 1 50 5 1 20 2 00 607 120 30P12 1 00 6132 10 00 Esot 1130 350 17
69. 13 227 172 15V 16V 18V 20V 22V 24V o BoA 020 33 36V 397 47V 51V 56V 68V 75V 50 YDS SOUTH OF MEOPHAM GREEN 188 395 E BGA Skirted 8042 4500 847 0 18 0 30 2 88 0 07 5 6 12 019 B108 016 2V7 3 3 3V6 3V9 4V3 4V7 5V1 CAR PARKING AVAILABLE Ee B13B 0 50 5V6 6V2 6V8 7V5 8V2 9V1 10V 11V OPEN MONDAY TO FRIDAY 9a m 5 30p m 8298A 6 50 7 Watt 8PnDIL 014 12V 13V 15V 18V 20V 24V 27V 30V 8417 5 95 56 ra Pn Dit 015 24 HOUR ANSWERPHONE SERVICE B5 34 Pin DIL Q THERMISTORS BATTERIES ACCESS AND BARCLAYCARD ORDERS WELCOME 9006 0 90 11 024 0 30 MANY OTHER ITEMS AVAILABLE 18042 10 00 1R 10K 026 QUAL 55 VAIDIO 10 23 ZV Rowec Mike 18045 10 00 CANS 027 210565 0 23 UK ORDERS P amp P 50 PLEASE ADD 15 17 x 0 15 8650 0 45 other Bricesion 65 075 EXPORT ORDERS WELCOME CARRIAGE POST AT COST ww 2 896 0 38 CIRCLE 40 FOR FURTHER DETAILS 79 WWW americanradiohistorv com the amazing specification of this easy to build project MC68B09E 8 16 bit microprocessor 8K system support monitor plus added utility and boot commands Integral eprom programmer MICROBOX II A NEW MICRO CONCEPT Do you remember the days when people built their own computers Well they are back with a vengeance MICROBOX the most advanced design ever offered as a build it yours
70. 17 in place of in type number For 240V primary UK insert 27 in place of X in type number IMPORTANT Regulation All voltages quoted are FULL LOAD VISA Please add regulation figure to secondary voltage to obtain oft load vol tage Sar ELECTRONICS LTD CIRCLE 09 FOR FURTHER DETAILS HIGH PERFORMANCE FREQUENCY COUNTERS HIGH RELIABILITY LOW COST The brand new Meteor series of 8 digit Frequency Counters offer the lowest cost professional performance avaiable anywhere Measuring typically 2Hz 1 2GHz Low Pass Filter Sensitivity lt 50 at 1GHz Battery or Mains Setability 0 b5ppm Factory Calibrated High Accuracy 1 Guarantee 3 Times 0 5 easy read L E D Display PRICES Inc adaptor charger P amp P and VAT METEOR 100 100MHz 104 36 Illustrated colour brochure METEOR 600 600MHz 134 26 with technical specification METEOR 1000 1GHz 184 36 and prices available on request SS 22 Designed and BLACK STAR LTD Dept WW 9A Crown Street St Ives manufactured BlacksStar Huntingdon Cambs PE17 4EB England PASS in Britain Tel 0480 62440 Telex 32339 ina Nie 7 t CIRCLE 14 FOR FURTHER DETAILS 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 natu
71. 2 450 750 BFR96 180p TIP32A 45 2N2907A 30 3N140 200 6 74 5153 100p 2000 90 2808 7908 50 2 459 300 BFX29 45 TIP32C 40 2N2926 12 3N141 2006 74141 7415154 300p 745153 Hee 20 12V 1812 50 7912 45p ZN1034E 200p 45 TIP33A 70 2N3053 40 3 201 200p SOCKETS 74142 7405155 140p 745197 300 15 2815 Sop 7915 45 2 1040 200 84 5 30 TIP33C 80p 243054 60 3N204 200 74143 7405156 125 745198 300 75 18y 7818 7918 50 2 134 23 BFX86 7 30 TIP34A 90 2N3055 55 40290 250p 8 25p 74144 7405157 100p S16 90 24y 7824 60 7924 45 2 234 950p BFX88 40 TIP34C 120 233442 140p 14 40 74145 745158 100 745174 300 75 sy 100mA 78105 30 79105 45 180p 120p 23553 240p 16 pin 45 74147 7415160 140p 749175 320 80 100 78106 30 50 30p TIP35C 140 2N3584 250p 18 pin 50 74148 TALS161A 140p 745188 180 400p gv 100mA 78108 30p ADI61 2 45 51 2 40 TIP36A 140p 2 3643 4 48 127 p 20 56 74150 74LS162A 140 P 220p 12v 100mA 78112 30 79112 50 107 8 18 6 33p 6 150p 2N3702 3 16 BYX36300 20 24 pn 75 74151A 7ALS163A 140 745194 400 90p 15 100 78115 30 79115 50 109 20 BFY90 90 50 2N3
72. 3 E TG501 01 Time Mark Generator hin Nace 495 2333 Trans Test Set 3 950 1 15 5 1 450 461A Amplifier 1KHz 150MHz 120 TF2603 RF Millivoltmeter 750 748 pectrum Analyser Plug TUR Generator for un 656 5 TEKTRONIX 1 5 506 2 3 950 503 Tracking Generator for use DC 1MHz Nh 1488 TV Insertion Generator 4 400 7L5 25 L3 01 Spectrum Analyser with 492 or 496 250 4815 RF Vector Meter 1503 3 000 Pl ug In with Tracker 5300 530 DMM Counter 1 176 Fixture for Curve Tracer 1 500 20Hz 5MHz 7 800 TEKTRONIX Portable Data Analyser 308 RACAL DANA Counter Timer 9514 eum Mq 5 0 100MHz Counter Superb Condition BE us Analysis 100 5 to 10 Sec Period Price 850 ata Lines IEEE Interface 20MHz Price 2 100 Trading Conditions Available on request Electronic Brokers Ltd 61 65 Kings Cross Road London WCTX 9LN Tel 01 278 3461 Telex 298694 CIRCLE 203 FOR FURTHER DETAILS y yy y V Uosat 2 not dead but poorly Uosat 2 the Surrey University satellite which ceased to transmit beacon signals after the first three orbits has now been traced Communications Commentary last month The giant SRI dish in Greenland managed to detect the 1 2GHz local oscillator which pin pointed the exact orbit ofthe craft Surrey engineers were gratified to have confirmed that the satellite
73. 300p TA7222 150 660 12 750p 2N426E 8 350p Fredin MHz 7420 0 74990 225p 745255 100p CA3046 70 LM733 75 147310 150 68B09E 16 Z80ADART 6505 ZN427E 800p 10 5 3225 7413 75p 74490 3095 745366 100p LM741 20 231 120 6800L8 48 80ADMA 10 P8275 27 2 428 8 450p 200 250p 7414 90 7415267 100 CA3059 350p 1 747 70 80 8035 550 280510220 SFF96364 245760 7416 POA200p 7415368 100p CA3060 350 1 748 40 10 100 8039 550 TMS9918 300p 7417 POA200p 210 7420 2 45760 5 74LS00 100 74537 3POA300p 80p 1 1011 480p TBA820 80 8080A 350p MEMORIES TMS9927 18 60 74 501 60 74LS374POA300 CA3086 60 LM1014 150p 950 225 8085A 1800 TMS9928 20 7421 100p P 7415975 100p 250 1 1801 300p TC9109 500 8086 22 2102 250 59929 16 250p 74 502 POA 100p S375 100p 25 250p 7422 1830 250p 210 350p 8088 2200 21078 500 74 503 60 7415377 180p CA3090AQ 250 350p 8271 45 2 662 250 723 SOP 74 504 7415378 150p 375p LM387 300p TCA220 350p 8748 3600 2111 35 400 5772 3276 1500 7425 TSP 505 70 7415279 140p CA3130E 90 1 1872 300p
74. 50 6516 1600 OB3 2 50 903 12 6 80 UCL82 1 75 4 1 75 6 4 1 25 12 07 175 5545 192 00 E92CC 875 EF80 175 Gric 15 00 435 QV047 3 50 UCL83 2 75 465A 60 00 6CB6A 2 50 12AV6 2 50 55514 114 90 E99F 9 10 EF83 400 GUSO 20 00 OG 250 QVO amp 100155 70 4125A 6000 amp CD6GA 5 00 12AV7 3 50 5552A 155 35 INTEGRATED CIRCUITS 7495 0 73 74136 0 51 74175 102 5200 2 30 7496 0 82 74141 0 89 74176 116 TBAS30 1 98 7400 0 16 7423 0 33 7460 0 18 7497 3 15 74142 230 74178 136 TBAS40Q 2 30 BASES CRTs SAPE i VCRS 7810 09 2740 017 7425 0 30 7470 0 38 74100 1 54 74143 2 60 74179 136 5500 3 22 ss 1000 7402 017 7427 0 30 7472 0 33 74107 0 45 74144 26 74180 120 322 B Gunskired 0 25 2BPI 9 00 15 00 7403 917 7428 043 7473 038 74109 0 73 74145 1 00 74190 190 TBAG73 220 BIG skirted 035 3BPI 12 00 2 7404 018 7430 017 7474 038 74110 0 51 74147 200 74191 1 90 700 1 52 BOA unskinted 0 25 zoo 25 00 7405 0 18 7432 0 30 7475 0 54 7411 0 71 74148 176 74192 1 90 7200 2 30 B9A wined 036 3EG 1090 2075 6332 7406 0 43 7433 0 40 7476 042 7416 1 85 74150 1 80 74193 190 7500 2 07 Int Octal 038 3FP7 600 20731 5807 Tube Bases 7407 0 43 7437 0 32 7480 0 56 74118 1 00 74151 0 94 74194 1 25 TBABOO 120 ent 0 55 eoo 20
75. 50 68838 9 95 E130L_ 1995 150 624 216 120 014 250 65 00 vaaoc 2K 2 395 195 8597 19 550 6973 36 3 37 4 50 PCF87 0 40 41 225 00 95 1 50 7025 2 50 iio EIOS 245 100 PCF200 180 400 vacak 120 6996 1 50 5005 0 95 7027A 450 0 95 090 PCF20 180 16 12 00 195 00 3AL5 0 95 4 00 608 085 50CD6G 115 7032 2 00 650 Eros 100 90 0 75 0 40 R17 150 v2464A 2K 2 335 195 6UBA 150 50JY6 2 95 7059 2 50 E186F 8 50 EFS 0 90 HBC9 080 1 35 R18 2 50 315 00 3AW2 3 35 0 58 6V6GT 0 85 52KU 2 00 7189 2 50 E2B0F C 1350 EF98 0 90 HF93 075 PCF802 0 60 R19 250 3 50 382 3 00 165 6X2N 100 61SPT 4 50 7189 2 35 E283CC 10 00 EF183 0 65 HF94 1 50 1 25 R20 1 20 15631 10 95 387 4 50 1 65 6X4 150 7581 2 50 7193 7 50 184 0 65 HK90 1 05 PCF806 100 1169 55 00 vP4B 4 50 3826 24 00 4 50 6X5GT 0 55 75 1 2 50 7199 4 95 ES 1880 EF730 180 350 125 861125 495 vPi33 200 3828 1200 2 35 6X5GTY 100 84 3 00 7247 2 00 Eras _ 100 EF731 350 HL23DD 400 PCH200 150 RG1 240A14 50 VR75 30 3 00 3 4 100 ee ee 7551 5 45 WIREWOUND RESISTORS BASES ETC ZENER DIODES 7558 945 o CALLERS WELCOME Jae 1400 PREFERRED VALUES 2 61 0 15 7587 26 95 4871680 91 876 7v5 8 2 9V1 10V TIV 12V
76. 59 00 BFX29 030 0 65 D13 47GH 55 00 M23 112W 55 00 V6008W 65 00 BEXB4 026 5008 013 51GH 34 85 00 M24 120GM 59 00 V6034WA 59 00 Hide 0732 125 0 65 013 5161 26 85 00 M24 120GR 59 00 V6048CLA 59 00 0 30 110145 065 D13 51GM 26 85 00 M24 120LC 59 00 V6048F 65 00 025 2 D13 450GH 01 55 00 M24 120WAR 59 00 V6048J 49 00 BEYSO 021 o 208 013 4716 26 55 00 M24 121GH 55 00 V6052GH 65 00 BEVE 22 2955 6 80 D13 550GH 65 00 M24 121LC 59 00 V6052GR 65 00 0 28 3088 0 55 013 600GM 59 00 M24 121WA 59 00 V6064BLA 65 00 077 1591 0720 013 610GH 59 00 M28 11LA 49 00 V6064BP31 55 00 86106 nize TV106 2 150 D13 610GM 59 00 M28 12GH 55 00 V6064CLA 55 00 026 24210 450 D13 611GH 59 00 M28 12LC 55 00 V6069GH 55 00 88103 ogs 21229 028 D13 611GM 5900 28 131 49 00 V6070P31 49 00 BRC4443 oge 2 2905 040 013 630GH 59 00 M28 13LG 49 00 V7016A 65 00 243053 040 D14 120GHO8 65 00 M28 13GR 49 00 7030 59 00 1004 02 0 75 283054 059 D14 121GHO9 65 00 28 13 49 00 V7031GH 59 00 BT106 149 305 099 D14 150GH 7500 M28131GR 55 00 V7031 67A 59 00 BT116 1 20 2N3702 032 014 1506 75 00 M28 132GM 55 00 7035 49 00 B7119 235 243702 042 D14 172GH 84 59 00 28 133GH 55 00 V7037GH 45 00 BT120 165 2N370 032 D14 172GR 55 00 M31 100GH 55 00 V8004GR 65 00 BUNS 022 3075 012 D14 172GV 55 00 M31 101GH 55 00 VB006GH 65 00 BU108 1 69 283706 012 D14 173GH 55 00 M31 182GR 55
77. 64 65 3 3k 82 38 86 88 90 66 79 100k 26 40 33k 29 30 54 75 note 22k R3 was 18k using 33k improves modifier balance 22k 84 45 80 12k 41 49 69 20k 43 use 2X 10k or 18k if necessary 15k 44 2 7k 48 2 2k 50 61 62 1 5k 52 2 2M 60Eirecarbon 5 0 33W 1 8M 59Eirecarbon 5 0 33W 1 2k 67 82k 68 55 120k 70 Mullard MR30 metal equivalent 5 0 25W 220 58 78 2209 72 7 51 1 6 to pin 5 MC796 Fig 34 from 1 12V rail component ref omitted from circuit Ro R and canbesetasa potential divider to suit higher video input levels If high Zin required omit R and set R to 4702 parasitic oscillation stopper Circuit reference Set for max chroma amp min 7 8kHz at transitions Potentiometers Cermet Value Circuit reference 5000 24 1k 32 5k 42 89 10k 87 100k 76 50k 71 Values determined by DL impedance Zo 752 800 1kO using LC network 2202 1502 1 6 9 4400 2220 1502 1 6kQ 4409 2220 R 1200 R 2200 8200 2200 682 1500 689 Rig 1 0 27 Rag 5102 1 5 0 5100 C 1 for max chroma not criticai Painton or Sigma choke Set tonotchfsc Painton or Sigma choke resonate top L to 4 07MHz end of C removed Resonate 3 013 Ls with C connected amp short 26 16TBIFILOR 16 0 16 3 20 13TBIFILOR 0 the outer pins of L together Disconnect output
78. 65 00 DH7 91 45 00 M38 1226W 65 00 800 0 89 TDA2610 2 50 DP7 5 35 00 M38 140 810 5 1 65 TDA2611A 1 95 A44 120 25 00 55 00 TBABI0P 1 65 TDA2640 260 AW36 11 25 00 DP7 6 35 00 M38 141LA 65 00 TBAB20M 0 75 TDA2680A 2 75 CME822W 19 00 7 11 45 00 8 1426 65 00 8200 145 TDA2690 245 CME822GH 25 00 DN13 78 35 00 M38 142LA 65 00 TBA890 2 50 TDA3560 550 CME1428GH 45 00 F15 101LC 49 00 M38 340P31 65 00 920 165 UPC566H 295 CME1428W 39 00 F16 101GM 55 00 M3B 341GR 65 00 TBA950 2X2 35 575 2 2 75 CME1523GA 39 00 F16 101LD 55 00 M3B 341P31 65 00 TBA970 2 95 UPC1025H 195 CME1523W 39 00 F21 130GR 55 00 M38 344P39 65 00 TBA990 149 UPCIO28H 195 14316 39 00 F21 130LC 55 00 M40 120W 59 00 1441 215 UPC1032H 150 CME1431W 39 00 F21 131GR 79 00 M43 12GM 01 65 00 270 130 UPCT56H 275 CME202GH 45 00 F22 11LD 53 00 M43 12LG 01 65 00 TCA270SQ 110 UPC1158H 0 75 CME2024W 45 00 F31 10GM 65 00 M44 120LC 65 00 650 250 1167 2 115 CME2325W 45 00 F31 10GR 65 00 M44 120GR 65 00 TCA800 2 95 125 CME3126GH 45 00 F31 30LC 65 00 M47 25GR 22 65 00 TCA940 165 1182 2 95 CME3128GH 45 00 F31 10LD 65 00 M50 120GH 65 00 TDA440 220 1185 3 95 CME3128W 45 00 F31 12LC 65 00 M50 120GR 65 00 TDA1001 195 UPCT91V 150 CME3132GH 45 00 F31 12LD 65 00 M50 120GV 65 00 GE CME3155W 45 00 F31 13GR 65 00 M50 120LC 65 00 TDA1006A 2 50 UPC1353C 2 45 CRE1400 25 00 F3113LD 65 00 M
79. 68 35V 1035 2235 33 35 47 16V 47 35V 6 8 25 6 835V 10 16V 1035V 1510 15 16V 15 25V 2263 22 16 3310 473 47 63V 47 6 100 ELECTROLYTICS Mainty Matsushita Panasonic amp Siemens AXIALS Wires each end v 63 100 350 63 100 500 25 63 100 350 25 40 63 16 25 40 63 100 25 40 63 100 350 25 40 63 100 25 40 63 100 16 25 40 63 100 10 16 25 40 63 100 16 25 40 63 100 16 25 40 63 16 25 40 16 25 75 89p 5 PCB wires one end Matsushita only uFd 16 10 16 10 16 10 16 10 16 10 16 30 16 10 16 10 16 10 16 741500 241501 741502 741503 741 504 741505 741508 741509 741510 741511 741512 74513 741514 741520 741521 741522 741527 741528 741530 741532 741533 741537 74 538 741540 741542 741547 741551 741 554 741555 740573 740574 741575 741576 744578 741583 74 585 741586 741590 740592 741593 741595 741596 7415107 7445109 7415112 7415113 7415114 7415122 7415123 7415192 7415193 7415194 7415195 7415196 7415197 74LS221 7415240 7415241 745242 74 243 7415244 7415245 7415247 7415248 7415249 7415251 7415253 7415257 741 5258 7415259 74LS261 7415266 7415273 74LS275 7415279 745280 7415283 7415290 7415293 7415295 7415298 7415299 7415323 7415324 7415325 7415326 7415327 7415347 7415348 74 5352 7415353 74 9362 7415365 7415
80. 80 57 BDY58 194 87195 195 197 BF198 BF199 BF200 BF244A Bf2448 BF245A BF245B BF246 BF246A 2468 BF247A BF2478 BF254 BF255 BF256A 256 256 BF257 BF258 BF259 457 458 BF459 BFR3S BFR40 79 BFRB80 81 9 BFS61 BFS98 BFX29 BFX30 BFYS3 5 19 BSX20 BSX21 BU104 BU105 80109 80126 BU204 0205 BU206 84208 80226 83265 80406 80407 80408 80409 80500 BUY 8S 430 J300 J310 MJ802 M 900 MJ901 M31000 M31001 MJ1800 MJ2500 MJ250 MJ2955 MJ3000 MJ3001 MJ4502 MJE340 MJE350 MJE2955 MJE2955T MJE3055 MJE3055T MPSA05 5 06 MPSA10 MPSA12 MPSA13 MPSA14 MPSA20 5 42 MPSA43 5 55 56 MPSAES MPSA66 5 70 2 MPSA93 MPStO 515 5405 5006 MPSUO MPSUS1 5056 5057 TIP28A 29 TIP30A TIP31A TIP32A TIP32C TiP33A TiP33C TIP34A TIP34C TIP35A 5 TIP36A TIP36C TIPATA TIPAIC TIP42A TIP42C 49 5 TiP53 54 10 112 115 117 120 122 127 TIP130 132 135 TIP137 TIP340 142 145 TIP147 162 2955 TIP3055 TIS43 VN10KM VN66AF ZTX107 2 108 zTX109 ZTX300 zTX301 ZTX302 zTX303 ZTX304 ZTX310 2TX311 2 312 ZTX33 ZTX314 ZTX320 217 330 ZTX341 ZTX450 ZTX500 27 501 27502 27 503 ZTX504 ZT
81. 84 Newman Street London W1A 4SE EWW 213 VOICE OPERATED SWITCH respond in 8ms when used by firemen with breathing aparatus orin fully enclosed anti radiation or laboratory suits It has also been tested successfully by RAF search and rescue helicopter crews and by free fall parachutists Sonic Helmets Ltd Communications Centre 202 Bradford Road Castle Bromwich Birmingham B36 9AA EWW 214 83 Sowter Transformers _ With 42 years experience in the design and manufacture of several hundred thousand transfcrmers AUDIO FREQUENCY TRANSFORMERS OF EVERY TYPE YOU NAME IT WE MAKE IT OUR RANGE INCLUDES Microphone transformers types Microphone Splitter Combiner transformers Input and Output transformers Direct Injection transformers for Gui tars Multi Secondary output transformers Bridging transformers Line transformers Line transformers to G P O Isolating Test Specification Tapped impedance matching transformers Gramophone Pickup transfor mers 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 Valve Amplifiers up to 500 watts Inductive Loop transformers Smoothing Chokes Filter Inductors Amplifier to 100 volt line transformers from a few watts up to 1 000 watts 100 volt line tra
82. Capacitors Polystyrene 2 125V Suflex Salford Lemco Value F Circult reference 220p 13 7 24 36 39p 5 56p 6 620p 18 100p 51 39 680p 19 150p 20 82p 26 23 270p 25 27p 34 35 62p 37 4 2n 46 Disc ceramic or red blue cap 10n 4 8 12 16 21 45 48 1 28 29 33 100 32 Polyester metallized 1 0 100 250V Mullard type 344 6 8n 40 470n 42 270n 53 Tantalum 20 Union Carbide or RS components 30p10V 1 2 22015V 3 17 31 30 22 47 55 22 10 10 4 7 25 44 Electrolytic Eire Mullard equivaient 1m6 3V 27 Transistors Type Circuit reference 2 3904 239 1 3 8 9 10 11 12 2N3906 2 4 6 18 5 18 or BC309 reference missing from the circuit transistor with R36 38 13 14 15 16 17 or VNO610L OrVN2222L TR19 f e t or M991BD C or 1167BD Integrated circuits 796 1496 1596 TDA2590 1 2 3 IC TDA2593 in thecurrentl C If used 12V regulator 47812 Diodes BZY88C6V2 D D BZY88 C4V3 05 13916 0 Delay lines DL Best to make the descrete LC 2 2200 or see text for alterations DL DL60 or DL700 not critical Observe R and Rz suit Z of line See table Resistors Mullard MR25 metal film 2 0 4W or equivalent metal film 5 0 2W Value Circuit reference 4 7 1 3 57 4700 12 16 31 33 81 13kQ 10 13 15 47 63 74 5600 21 18 1500 23 37 1k 22 4 5 46 6800 8 73 36 27k 14 85 1009 83 34
83. Computer waits a few milliseconds n 0 Computer reads data byte 07 00 Computer sends pulse on 2 to clock 1010 Yes Terminate interrupt At switch on the counteris set to zero and its synchronism is checked each time the keyboard is read The delay allows for key bounce and for the fact that ts impossible to play all the notes of a chord simultaneously 23 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 SR 531 USB LSB AM CW 100 Hz Steps Static Transportable mie9 COMMUNICATIONS RECEIVER 58532 AF GAN RF GAN 9099 jm DESIGNED AND MANUFACTURED TO HIGHEST INTERNATIONAL SPECS RF PEAK WIDEBANI 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 Part in 107 Automatic or Manual Stop Power Supplies 110 240V AC and 24V DC Dwell Variable from Keypad 1 to 9 seconds FULLY MODULAR 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 Tuning Keypad and Spin Wheel Manual
84. Hewlett Packard Time Interval Probes enhanced Frequency Synthesiser 30 HZ to 30 5363A 400 The flexibility of the 1 2kW amp stems from its division into 4 potentially separate MHZ 400 00 RECEIVERS amplifiers of 300W each downrateable with cost savings to 150W These can be Transmission Measuring Line 75 to paralleled increasing current capability or seriesed bridged in pairs doubling 305MHZ 400 00 Eddystone 830 7 300Kcs to 30Mhz250 00 consequence a large variety of amplifier load strategies Reflektometer 300 to RAI7L implemented 208 T eceiver 0 As ever Pantechnic offer a full range of customising options including DC coupling Unbalanced Standard Attenuator DPU Mercer 155 Electronic Pneumatic ultra high slew etc Contact Phil Rimmer on 01 361 8715 with your particular 0 1500 MHZ 500hms 50 00 Gauging system os wre exemplary MISCELLANEOUS 350 80 Avo 215 3 Breakdown Prices plus V A T SAE Enquiries A wide range of other amplifiers and other modules available Tester 195 00 Xt Avo Universal Bridge 8150 2 9500 WANTED Price and Delivery Advance X Y Recorder 96 65 00 Test Equipment Receivers Valves m i Cable PCB s Etc PANTECHNIC Dent ww7 Technical Multiple Earth Tester Components able s Etc 132 HIGH ROAD Phil Rimmer NEW SOUTHGATE 01 361 8715 86 Bish
85. K20 520 per annum K1 Stg 0 8177 Level of appointment will depend upon qualifications and experience The initial contract period is for approximately three years Other benefits include a gratuity of 24 taxed at 2 appointment and repatriation fares leave fares for the staff member and famity after 18 months of service settling in and settling out allowances six weeks paid leave per year education fares and assistance towards school fees free housing Salary protection plan and medical benefit schemes are available Detailed applications two copies with curriculum vitae together with the names and addresses of three referees and indication of earliest availability to take up appointment should be received by The Registrar Papua New Guinea University of Technology Private Mail Bag Lae Papua New Guinea by 30 July 1984 Applicants resident in the United Kingdom should also send one copy to the Association of Commonwealth Universities Appts 36 Gordon Square London WC1H OPF from whom further 2618 information may be obtained ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com sudsod 1 SC Z 0098 068 10 10 2040 151 10 ZAZ 21 UOISIAIG suiajs S a2uajag NHOHL Aa4jpo5 ans 10
86. MPSA93 40 2 1613 36 2N6290 10 400 200p P 74LS260 4012 30p TiL220Red 10p 1 Boon 80380 60 MPSUOG 63 2N1711 36p 25 1306 25A 400V 400p 245261 4013 TIL222 Gr 122 1321 3 1305 80677 40 MPSUO7 2N2102 70 25 1307 EL 74LS266 4014 TIL228 Ye 15 ri 330 1405 BE244B 40 MPSU45 90 2N2160 350p 25 1957 74L8273 4015 80p Rectangular 7750 60 200p 822568 50 MPSU6S 78 2N2219A 30 25 1969 150p 2 7V 33V 74LS275 4016 50p 74C925 LEDs R G Y 302 Bargraph 225p 257 8 40 TIP28A 35 2N2222A 30 2502028 80 400mW 9p 7ALS279 4017 75p 74C926 CEST BF337 30p 29 40 2N2369A 30 25 2029 200p 4way 90 iw 15 7415280 4018 75 74C928 BFR39 32 35 2N2484 30 25 2076 160p Bway 120 74 5283 4019 72168 01704 146p BFR40 1 32 40 2N2645 50 25 2335 200p amp way 105 745290 4020 2 1040 870p 01707 Red 14 BFR79 32p TIP31A 40 2N2904 5 25 2612 200p 10 way 150p PLEASE ADD 50p p amp p amp 15 Se ADD tek e MAIL ORDERS 17 BURNLEY ROAD LONDON NW10 1 Orders from Government Depts amp Colleges etc welcome SHOPS 17 BURNLEY ROAD LONDON NW10 Tel 01 452 1500 01 450 6597 Telex 922800 305 EDGWARE ROAD LONDON W2 Detailed Price List on request Stock items are normally by return of post EL
87. Quadrant House The Quadrant Sutton Surrey SM2 545 PHONE LUCY O SULLIVAN 01 661 3033 DIRECT LINE Cheques and Postal Orders payable to BUSINESS PRESSINTERNATIONALLTD and crossed ALWAYS AHEAD WITH THE BEST 7 000 22 000 Where does your interest lie Graphics Comms Robotics Simulation Image and Signal Processing Medical Automation Avionics Sonar 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 Technicians Engineers and Managers For free professional guidance Call 076 384 676 till most evenings or send your no stamp needed to ELECTRONIC COMPUTER AND MANAGEMENT APPOINTMENTS LIMITED Freepost Barkway Royston Herts SG8 8BR MICROPROCESSORS IN SOUND RECORDING We make a range of timing and control products in the professional audio and broadcasting field and have a vacancy for an engineer to be in charge of production and test The successful applicant would have experience in digital and microprocesor circuits we use 6802 formal qualifications are important but not essential an interest in sound recording would be an advantage A certain amount of field work would be involved so a driving licence would be required A small expanding company such as ours is greatly in need of
88. STitimers B control register STI B data register STI timer A data register STi usart control register STi receiver status register STitransmitter status register usart data register STI sync character register STI timer D data register STi timer C data register STi active edge reg STlinterrupt enable register B STlinterrupt enable register A STI data direction register STI tlmers D control register ister port which is automatically cleared on RESET or use a 74LS373 and make link 201 for a tri state port enabled by applying a low level to pin one of the port connector The latter option means that this port may then be connected in parallel with the eight bit input port to form a bidi rectional i o port Spare I lines on the STI pins 11 to 13 are also available from pads adjacent to the i c pins as are the outputs from the four frequency genera tors Link 203 should be wired in on the basic system but may be removed to free pin 16 of the STI for use in an interrupt daisy chain Table 2 and 21 respectively for non commercial users and er discounts are available for those buying more than one software package at once John Adams is considering producing a kit of i cs for SC84 For details of these items send an s a e to him at 5 The Close Radlett Herts A switch regulated power sup ply and further constructor s notes are subjects of a future article ELECTRONIC
89. TEKTRONIX bars cross hatch dot blank raster centre SWEEPERS FILE MANAGER SYSTEM MODEL ROTRON INSTRUMENT location i i i LABGEAR CM6004 PG Monochrome UHF PATTERN GEN ELONIC 2003 System 800 1500MHz 325 4907 Option 31 Third disc drive COOLING FANS ERATORS Grey Scale variable level cross hatch 4 Dot pat TEN SERE EUM DAN in S175 eu uae Supplied in fully tested excellent condi terns 240 tion as follows 115V 442x4 2x12 5 230V same size LABGEAR 6016 5 SIGNAL STRENGTH PLEASE NOTE All the pre owned equipment shown has been carefully paren tested our workshop and reconditioned where necessary It is sold in 5 50 115V 3x3x1 2 4 230V 3 size 45 first class operational condition and most items carry a three months brand new 6 Also small quantity 115V Please note all these prices INCLUDE VAT Carriage 2 guarantee For our mail order customers we have a money back scheme 472 size brand new 6 Postage each gach item epairs and servicing to all equipment at very reasonable rates PLEASE 50p please WW 0 ADD 15 VAT TO ALL PRICES Las 542 CIRCLE 55 FOR FURTHER DETAILS M amp B RADIO LEEDS THE NORTHS LEADING USED TEST EQUIPMENT DEALER TSPECIALISTS OEM USERS Dual T Del Fluke RMS Differenti
90. a bit rate of something in excess of 640kbit s In near instantaneous digital companding the analogue input signal is sampled and digitally coded to an accuracy of 14 bits per sample Only ten of these 14 bits are actu ally transmitted the ten bit window mov ing up and down the 14 bit range according to the peak signal level occurring during a block of 32 samples The receiver decoder is instructed on the correct placement of the window by a three bit scale factor word sent with each successive 32 sample block By this method low level pro gramme signals are transmitted with 14 bit accuracy The accuracy progressively decreases down to ten bits per sample for the higher signal levels but the conse quently increased quantization noise is masked by the higher level of programme The sampling frequency must be at least twice the highest modulating frequency system has been devised based on earlier work at the BBC Research Department and its outline parameters are given in Table 1 The proposed system which is still under development was not used in the South Wales tests a pseudo random binary sequence generator being used instead However the important factor was to test the modulation system employed and this is dis cussed next The proposed sys tem employs a bit rate of 704kbit s chosen because it is a multiple 22 of the sampling fre quency which could lead to sim plification of the de
91. a bright and intelligent person will not only fill this post but also become involved in all parts of the company Salary in the range of 8 000 10 000 Apply in writing to STEPHEN BROWN APPLIED MICROSYSTEMS LIMITED TOWN MILL BAGSHOT ROAD CHOBHAM WOKING SURREY RADAR RADIO ENGINEER SALARY Scale 3 4 up to 8 700 approx p a including shift pay and weekend allowances HOURS 37 hr wk including Saturday and Sunday no night duties CITY AND GUILDS FULL TT4 TECH ONC or equivalent a clean driving licence Repair and maintenace of airport 10cm amp Scm ground radars Navigational aids including ILS and Communications equipment Applicants should have considerable experience and be capable of working without close supervision Fault finding to component level is essential Application forms are available from Airport Director Southend Airport Essex SS2 6YF Tel no 0702 40201 Complete applications to be returned by Friday 6th July 1984 2639 QUALIFICATIONS DUTIES ELECTRONICS amp WIRELESS WORLD JULY 1984 1926 BROADCASTING ENGINEER LATIN AMERICA Toworkas atechnicaladvisor with a Latinamerican organisation for edu cation by radio with 40 affiliated radio stations in 17 countries The engineer will initially be based in Quito Ecuador and will later travel to radio stations in other countries The job consists of planning and running training courses f
92. about 30 seconds which should allow enough time for the calling modem to establish communica tion Control of RL then passes to the CD or BCD outputs of ICs if the incoming carrier is lost the relay will be released and the call terminated To enable auto answering it is necessary to disable RTS until the answer sequence of IC is complete For this reason the amendments shown in Fig 3 should be made to the computer interface section of the modem The additional connection to pin 16 of IC is to ensure that the DTR signal is removed briefly between auto answered calls Without this the modem will not generate its burst of answer tone However a problem may arise if a large transient occurs on the line as 5 15 moved The first mon ostable in IC may be triggered removing DTR temporarily If this happens a way of dealing with it is to inhibit the monostable except when auto answering is enabled Omit and but connect pin 6 of IC to pins and 11 of ICi If the components of the auto answer section are ommitted entirely a 47kQ resistor must be inserted between pins 12 and 16 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com of the IC position to ensure that pin 1 of the Am7910 is tied high Note also that the dotted links LK and LK in last month s cir cuit diagram are shown reversed if a full RS232 interface is required the RTS input of IC should be linked to pin 11
93. and as the capacitors charge cannot change instantaneously so does the upper plate s potential i e thestrobe potential dropsto 2 5V In due course C discharges through R then recharges with reverse polarity through R and the strobe returns to 2 5V When ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com the switch is opened C tries to discharge through R and in doing so pulls the strobe line above 2 5V by an amount depending on the values of the resistors The capacitor now dis charges and to the orig inal steady state voltage through R and R so key status can be read at point S several keys are connected to the strobe rail each with their own RC networks their behav iour will be similar but step mag nitudes and associated time con stants will depend on how many keys are pressed For example if 48 keys are pressed a tricky feat even using arms instead of hands pressing the 49th key places the last C in parallel with the 48 others and limits the step size to about 100mV However as long as the system can detect the smallest possible step and react to the minimum time con stant while the maximum time constant is short enough to ensure that recovery occurs before one has a chance to press the next key all is well Compo nent values shown allow the key board to respond to chords of any number of notes that I have managed to re
94. and the distribution centre can obvi ously be of the ordinary copper coaxial cable type or by optical fibres either of which could be arranged as a tree and branch or switched star topology both of which are shown in Fig 3 The switched star system is currently favoured as offering the greatest future potential for system expansion In contrast over 80 of all American coaxial cable sys tems use a tree and branch topol ogy Owing to the inherent diffi culties and signal losses involved in splitting the signal in an optical fibre it is likely that its use in a tree and branch network would be restricted to the main trunk Ina switched star network however the signal paths are a series of point to point transmissions ideally suited to the characteris tics of optical fibre technology Most of the field trials that have been conducted around the world UK USA Canada Ger many and Japan to assess the potential of fibre optic transmis sion links have relied on some form of analogue intensity modu lation of thalight source The rea son is simply that frequency divi sion multiplexing onto ever higher frequency carriers has been the traditional manner in which to multiplex telephone and by extension television channels Analogue intensity modulation performs satisfactor ily with coaxial cable techniques but does not ideally suit optical sources since in general they are non linear unless pre biasing techniques
95. are employed Even then circuit complexities arise because the lasing threshold of a semiconductor injection laser is temperature sensitive The best properties of the optical trans mission systems discussed in the previous articles are brought out by binary intensity modulation i e on or off For a fully inte grated data network this is obvi ously the best form of modulation as it renders unnecessary any form of modulation change between the computing section and the distribution section However there are certain bandwidth penalties to be paid when attempting to encode tv channels in a completely digital format in an analogue format a PAL colour signal will occupy a bandwidth of 6MHz but with eight bit p c m digital encoding this increases dramatically to around 120MHz to satisfy sampl ing requirements at an appropri ate multiple of the colour subcar rier In other words a single digi tal tv channel would occupy the equivalent of a 140 2 optical fibre telephone trunk circuit Even with bandwidth compres sion techniques this figure is only reduced to approximately 70MHz Clearly there is a prob lem in providing every user in a tree and branch network with an optical fibre and receiver elec tronics with sufficient bandwidth at an affordable price capable of bringing in perhaps 10 or 20 simultaneous tv channels and ancillary services A switched star network over comes many of these problems by employing ups
96. ator for Freefone 2296 Ring back systems dial the num ber let it ring once replace the hand set and then dial again Addresses Barrie Electronics Ltd Unit 211 Stratford Workshops Burford Road London E15 2SP 01 555 0228 Combe Martin Electronics Kin Street Combe Martin Devon EX34 Computer Concepts 16 Wayside Chipperfield Hertfordshire WD4 91 09277 69727 Electrovalue Ltd 28 St Jude s Road Englefield Green Egham Surrey 20 OHB 0784 33603 Maplin Electronic Supplies Ltd P O Box 3 Rayleigh Essex SS6 8LR 0702 554155 Molimerx Ltd 1 Buckhurst Road Town Hall Square Bexhill on Sea East Sussex 0424 220391 Pace Software Supplies Ltd 92 New Cross Street Bardford BD5 8BS 0274 729306 Technomatic Ltd 17 Burnley Road London NW10 1ED 01 452 1500 47 STEEL DISHED WASHER E Ary OUTER 25 x TOROIDALS 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 field and thanks to 1 PRICE WINDING S Our large standard range is complemented by our SPECIAL DESIGN NEOPRENE WASHERS INSULATION section which offer a prototype service within14 DAYS together gt with a short lead time on quantity orders which can be programmed PRIMARY CORE to your
97. azine on a digital multichannel tape recorder In this design I achieved a rate of 22 000 baud using complex but well known techniques called Miller or delay modulation However all these very high speed designs includ ing my own rely on the ability to record single high low or low high signal transitions The suc cess or otherwise of the technique depends not only on getting the electronics right but also on tape quality and the mechanical opera tion of the cassette deck It is very sensitive to imperfections in the tape quality dirty tape heads and indifferent transport of the tape across the head In my opinion the techniques are unlikely to be successful unless only the best tapes are used the cassette deck is of the highest quality and the tape heads are regularly cleaned A technique that is far less sensitive to these three sources of error is frequency shift keying Using a few modern i cs a vol tage controlled oscillator and a phase locked loop a modulator and demodulator are easily designed that are easy to set up and reliable in use In f s k the output of an oscillator is simply switched between two frequen cies to represent the low and high logic states There is a maxi mum rate at which the switching between the two frequencies can take place somewhere between a fifth and a tenth of the mean of the two frequencies is a good rule of thumb Using a good set of record playback elect
98. been on special offer from another sup plier at 4 plus VAT OUR PRICE IS ONLY 3 99 INCLUDING VAT AND POSTAGE Circuit if required 35p COMPLETE STEREO TUNER MODULE Three band LW MW FM Stereo Tuner fully assembled PCB 165 x 85mm 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 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 Theread after write head uses an NRZ system with separate tracks for clock and data power supplies of 5v 12v and 12v are 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 origin cost ONLY 44 50 inc VAT and postage Data inc circuits and layouts of PCBs 3 50 COMPONENTS We now list a wide range of individual components many of which are not available elsewhere Send for your copy of our latest list which also gives further information on our Kits Personal callers are always very welcome but please note that we are closed all day Saturday ALL PRICES EXCLUDE VAT UNLESS STATED 0691 652894 HIGH QUALITY REPLACEMENT CASSETTE HEADS af Do your tapes lack trebie A worn head c
99. by David Ellis Lancaster University s music department is studying possible uses of microcomputers aspects of its work including the training of musicians music edit ing and research into music anal ysis We felt from the outset that a musician friendly input device was essential for acceptance by potential users and given the cost of commercial systems not to mention their shortcomings we decided to develop a straight forward and cheap keyboard interface for the BBC microcom puter The outcome is a keyboard and interface costing around 50 David Ellis CAMI Some educational music programs Electronics and Music Maker Oct 1983 in components and drawing about 60mA from the computers 5V supply which hasn t caused prob lems even while two disc drives are powered from the same source Design considerations Synthesizer applications were not considered a prime objective although the design can be used to play the computer s own sound generator or external units No attempt was made to make the keyboard touch sensitive to mea sure the speed of key depression simple on off key switches will suffice Uses envisaged for the interface suggested that it should be fully polyphonic i e should accept chords and should not be restricted to the one note at a time characteristic of typewriter style keyboards designed for computer input Finally rapid response was required and in some circumstance
100. captured by These important positions present a major opportunity to the the highly advanced technology now being employed Your challenge professional engneer set to establish a career in Hi Tech Electronic will be to integrate the product with the design of the ATE providing and Automatic Test Equipment Design and Development Our client innovative solutions to both design and test methodology problems provides an attractive salary package the possibility of travel and full E company benefits including five weeks holiday and a generous relocation package to an attractive location in 5 England PRINCIPAL DESIGN ATE ENGINEERS HIGH TECHNOLOGY ATE EQUIPMENT S ENGLAND to 16K From original concept you will be providing an active contribution to the design and development of systems using analogue digital signal processing digital data electro optics infra red and millimetric circuits and systems You will provide a consultancy service to development teams on testability BITE and ATE app cations developing test ability and methodology as applied to future and specialised microelectronic packaging To find out more and to attain an early interview please contact KEN JACOBSEN in complete confidence on Heme Hempstead 0442 47311 during office hours or one of our duty consultants on Heme Hempstead 0442 212650 evenings or weekends Alternatively write to him at the address below
101. carry certain network services should not be permitted to strip the new offerings from the tv signals The system combines sophisticated features and high reliability at an extremely competitive price ADEKS was designed specifically for installations such as this and is the result of cooperation between BT and CAA communications engineers ADEKS keyboards are small units incorporated into the air traffic controller s desks At the touch of a button users have instant access to all kinds of internal public and emergency telephone lines Incoming calls are indicated according to their priority The control system is designed to minimize disruptions and uses multiple processors and back up cable routes to ensure high integrity Any components failure can effect a maximum of one console or two lines Self checking routines and battery back up are also provided Cables are smoke and fire resistant and special immunity to radar and radio interference has been built in One system can handle up to 116 lines to 60 consoles and systems may be linked for larger installations ADEKS can also be interfaced to radio circuits ADEKS is installed in the new stalk mounted control tower at Gatwick ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com Electronic Brokers POWERFUL AND RELIABLE Microcomputers 64K with double disc drives British made 2 80 processor 4MHz circuit 2 built in high q
102. 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 WW CIRCLE 20 FOR FURTHER DETAILS 90 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com ANY SOUND SYNTHESIZER Up to eighteen different sound envelopes may be stored in the synthesizer amplifier unit from Haven Automation These may beselected and mixed to emulate any combination of sounds from birdsong to double bass The synthesizer was originally developed to reproduce the complex sound spectra of a ship s engine room to make training exercises more realistic The company is now exploring markets in the electronic enhancement of musical instruments speech therapy vehicle and aircraft simulations and the generation of sound effects The system fits into 19in racks and includes a sound simulator three mixer amplifiers and distribution unit Each circuit is identical to the others except that the different sounds are retained on eproms The units interconnect and are controlled through a GPIB which is also used to control a set of filters to produce a required sound Eighteen signals from the distribution unit are combined in the three mixer amplifiers to give the desired mix and output level for a specific environment Haven Automation Ltd Cwmru Industrial Estate Gendros Swans
103. communication comprising MARCONI TF2502 RF Power Meters DC two racks containing ten 100W Grampian audio amplifi 1GHz 10w fsd 350 Surplus aah DISK CARTRIDGES available ers and receiver for background music microphone MARCONI TF2701 In Situ Universal Com E uantity only remaining at 15 each Car _and pre amp controller COMPLETE SYSTEM 550 ponent Bridge 250 riage 50 OPTICAL ISOLATORS HEWLETT PACKARD 3450A Multi Function Digital Multi Meter ROHDE amp SCHWARZ SDR AM Signal Generator 0 3 1GHz ET SPERRY UNIVAC M4000 opto isolator units providing 2KV TEKTRONIX 2901 Time mark SWITCHING POWER SUPPLIES insulation between Modems and Terminals 25 way D connec ROHDE amp SCHWARZ Resonance Frequency Meter 470MHz 2 5GHz The following DC power supplies are available now tors RS232C Interface and out Measures 9 5 7 Com ROHDE amp SCHWARZ Polyscop SWOB II from stock in limited quantities All fully tested and plete with handbook 2 25 2 METROHM 500V Insulation Testers Transistorised 40 pp 1 50 guaranteed STEPPER MOTORS BRUEL amp KJAER Heterodyne Voltmeter 0 5 240MHz 3 5V 10 Amps 15 15V16A 110VIN 20 AIRMEC Display Oscilloscope 279 4 trace 14x10 CRT 195 5V 20 Amps 20 40 Amps Brand new stock of ASTROSYN Type 20PM RIKADENKI 3 channel Chart Recorder Model B 341 BY ce Pieces n Ae stepper motors 28V DC
104. complete with NEVER be repeated Standard CENTRONICS als Composte 75 ohm vid inp Black amp White parallel interface for direct connection to BBC CRT 45 00 or Green CRT 55 00 ible t ORIC DRAGON Superb pnnt quality with full Carr amp Ins 5 00 miniature reversible fan brushless pin addressable graphics and 4 type fonts plus B 15 CASED Made by the British KGM Co servo motor tor extremely high air flow 1 4 E THIGH DEFINITION internal PROPORTIONAL SPACED D fot y d almost silent running and guaranteed 10 000 4 MODE for WORD PROCESSOR applications 80 132 esigned for continuous use aS a data hr life Measures only 62 x 62 x 22 mm col Single sheet s ket handl display station unit is totally housed in an Current cost 32 00 OUR PRICE ONLY eur ONLY trom DISPLAY attractive brushed aluminium case with ON 12 95 complete with data at the ridiculous price of ONLY 199 00 VAT Complete with OFF BRIGHTNESS and CONTRAST MUFFIN CENTAUR standard 4 x 4 x 1 25 full manual etc Limited quantity Hurry while stocks last controls mounted to one side Much Fun SUR tos ur DRAN NEW 240V Options Interface cable specify for BBC attention was given to construction and at 10 50 1000 s of other fans Ex Stock DRAGON CENTRONICS 36 way 12 50 Spare ribbon reliability of this unit with features such as
105. d us Under IBM s scheme for support for academic institutions they are sending two data processing specialists to the OUP to assist the dictionary editors with the task of updating 14 NEWS One network nottwo in UK Britain is urged not to follow the American example and have separate telephone and tv networks In an article in the Sunday Times of June 4th Warren Partridge an American lawyer and telecommunications business consultant points out that with the denationalization of British Telecom Britain is heading toward the same system that the US has developed in the 70s onethat has a private telephone monopoly underfunded cable tv and unnecessary investment in all Sorts of services to be carried into homes on several wires Now is the time he maintains for all these services to be combined into one network The American experience is the development of two separate and inadequate systems The telephone network is neither designed for local transmission of high speed data nor tv pictures the other a cable tv system is not designed to provide telephone services Both systems suffer from not getting the income that could accrue from the services provided by the other Mr Partridge suggests that Britain s cable tv franchising process could be used as the mechanism for privatizing BT Britain could be divided into a few large combined telephone and cable services The condition attached to awarding a
106. delay Sweep Large Screen 400 409 TELEQUIPMENT 075 Dual Trace SOMHz Dela Sweep 35 11 S E LABSSM11 Dual Trace 20MHz 200 5 SOLARTRON SCHLUMBERGER CD1740 dual trace SQMHz dual TB delay sweep 300 14 SOLARTRON 01400 dual beam 15MHz 30 15 TELEQUIPMENT 043 dual beam 15MHz f90 STORAGE OSCILLOSCOPES 19 TELEQUIPMENT dual trace 10MHz 375 20 549 with 1A1 plug in dual trace 30MHz dual TB delay sweep 400 22 HP SIGNAL ANALYSER 54808 memory display with 54868 and 5485A Plug ins 425 28 MARCONI UNIVERSAL BRIDGE TF1313 0 25 225 29 MARCONI UHF SIG GEN TF1060 2 450 1200MHz late style 1 3 150 31 MARCONI UNIVERSAL BRIDGE TF868 range 50 MULTIMETER 04324 33 SWITCHED RANGES 20KOhms per VOLT Complete with Leads amp Batteries BRAND NEW 1 YEAR GUARANTEE fi6eachP amp P 3 32 MARCONI WIDE RANGE OSC TF1370A 10 10 Sine 10H2 100kHz square 95 36 POWER METER TF893A 20Hz 35kHz 75 38 MARCONI SENSITIVE TF2600 10 10 1mV 300 M 41 HP PULSE GEN 222A Repetition rate to 10MHz 42 HP PULSE GEN 214A 200 watt pulse power 51 LEVEL RECORDER 2305 solid state 52 LEVEL RECORDER 2305 valve 53 MICROPHONE AMPLIFIER 2603 54 B amp K RANDON NOISE GEN 1402 56 BAK RMS AUDIO VOLTMETER 2410 59 MICROPHONE 4111 with stand and cable 65 WAYNE KERR UNIVERSAL BRIDGE B22 Mk 3 imeter indicator with low imp adaptor 0221 Mk 3 175 68 WAYNE KERR CDMPDNENT BR
107. desirable but not essential The basic salary offered will be around DM3900 monthly Certain allowances will be payable in addition depending on personal circumstances An initial contract of 3 years will be offered which can be renewed PLEASE WRITE BRIEFLY FOR AN APPLICATION FORM QUOTING REFERENCE N 83 23 TO EMBL PERSONNEL SECTION POSTFACH 10 2209 D 68900 HEIDELBERG os 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 were 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 9561 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
108. elected as secretary of the Region Executive Committee the post held until his death in 1981 by Roy Stevens G2BVN and since then by Eric Godsmark G5CO Region 1 conferences are held once every three years At this year s conference member societies were urged to Seek from their national adminstrations a 50MHz amateur allocation and the removal of Syledis pulse transmissions from the 430MHz band The conference also recommended that no f m repeaters should operate between 144 8 and 145MHz and rejected proposals to allocate channeis and repeater channels for narrow band f m transmissions in the 22MHz band It endorsed a provisional band plan for 1296MHz and a new world wide locator squares system fromJanuary 1 1985 The IARU Medal was awarded to the Russian amateur N Kazansky UA3AF The conference also discussed the proposed new constitution for the International Amateur Radio Union Rather more success in dealing with interference from WWW americanradiohistorv com Syledis type transmissions in the 430MHz band is reported from California where pulse transmitters on 433 and 437MHz have now been turned off In brief A major solar flare possibly the largest in Solar Cycle 21 was recorded at the end of April The RSGB 1984 National Convention at NEC Birmingham attracted over 6000 people on Saturday 28 April and some 5000 on the Sunday The 1985 Convention is to be held at the National Exhibitio
109. fetching of a character code to the character latch forces charac ter code to zero While it might seem simpler to gate SEL directly with the video output to produce blanking due to the pipelining technique SEL would blank the display between one and two characters too early The v d u memory consists of 6Kbytes of static memory Address and data lines to the v d u memory i cs do not corre spond to their specified A or D numbers but this doesn t matter The order used was chosen to ease p c b layout After all if a data byte is written into memory with a particular addressing pat tern that same byte will be accessed when the same address is applied The lower 11 bits of the address supplied by the multi plexers are fed to all three memo ries in parallel The next two most significant bits of the add ress feed a decoder which acti vates one of four output lines The four lines pass to the memory i c enable inputs and the 6845 so that within the addressing range 08000 to O9FFF for which SEL is active the memory is mapped at addresses 08800 to O9FFF and the 6845 control registers from 08000 to 087FF Effectively the 6845 only needs two locations one to receive the number of the internal register that the c p u wants to access and one which appears as that register The fact that it has been allocated another 2046 in the rather coarse decod ing is not a loss though and it simplifies both hardware and
110. fledged PUN Quality Micro Y NEW SUPER LOW PRICE of ONLY 65 00 printing switchable 10 or 12 pitch full width 381 mm paper handling with up VAT Carr 163 characters per line friction feed rollers for single sheet or continuous TUM internal buffer standard RS232 seria interface with handshake MICRONET PRESTEL or TELECOM GOLD etc 2 wire uirect connect 75 baud transmit 1200 baud receive Data i o 5232 D socket Guaranteed working with data 49 95 MODEM 20 2 same as 20 1 but 75 bauc and dust cover Order NOW or contact sales office for more information Optional extras RS232 data cable 10 00 Tech manua 7 50 Tractor feed 140 00 Spare daisy whee 3 00 Carriage amp Ins UK Mainland 10 00 receive 1200 baud transmit 130 00 0 ELECTRONIC ie PME ges 627000 TRANSOATA 307A 300 baud acoustic 66 D SCO U N T COMPONENTS CASO DecwnterElAor20ma 270 00 EQUIPMENT KL8JA PDP 8 async i o 175 00 NEW PS12123 a rl a Due to our massive bulk purchasing programme which enables us 10 bring you the best possible Dice DD Sear ean epi ree V23 1200 75 full duplex Or 1200 1200 bargains we have thousands of 1 Transistors Relays s Sub assemblies controller 450 00 Switches etc etc surplus to our requirements Because we don 1 have sufficient sto f any duplex modes Full auto answer via modem MSC4804 Equiv MSV11 L 256k bytes CPU LED status indicators CALL
111. for engine and fuel system manufacturers worldwide Anadditional ELECTRONICS TECHNICIAN is now sought someone aged 22 35 who has served a recognised apprenticeship and has an ONC HNC to be involved in work of an interesting and practical nature featuring assembly wiring and testing one off PCB s prototype machines and test rigs followed up by analysis and reporting of results 2 years relevant experience is therefore essential The salary offered will be according to your age experience and qualifications If you would like the opportunity of working for an award winning company with a secure future please apply for an application form from Rod Mitchell Personnel Manager Leslie Hartridge Limited Tingewick Road e Buckingham Bucks MK18 1EF Tel Buckingham 0280 813661 29 Hartridge A Lucas Company 2630 Power Supply Development Engineer Negotiable Salary Coventry Our sustained growth in the expanding new telecommunications technology combining voice data and video services is creating some exceptional opportunities at the Company s Headquarters in Coventry Applicants must have at least two years experience in the field of Switch Mode Power Supply design or in a related field where he she has acquired a sound understanding of closed loop control theory and or magnetics will be an advantage The successful candidate must be able to work as a member of a small team and make a real contribution to
112. for file hand amp xBAW62 Analogue ground Connected to p s smoothing capacitors 1 A4 Telephone socket Handset disconnect 5 A L GN W R Sa To telephone line C37 2921250V To DoglFig3 600000000 Line C36 292 1250V 220 16 ling This protocol allows virtu ally error free transfer of Ascii text or program files over event the poorest lines The file to be sent is transmitted in 128 byte blocks with error checking on each block If an error arises the receiving computer asks for the block to be sent once more Error checking is used also in viewdata terminal programs for telesoftware file downloading Viewdata software for a var iety of home and business compu ters is available from Micronet 800 For the 300 baud modes Maplin Electronics can provide modem interfaces and software for the ZX81 Spectrum Dragon Oric VIC 20 and Commodore 64 For the BBC Microcomputer there is a wide choice of software including packages in eprom Computer Concepts communica tor 16Kbyte provides emulation of a DEC VT 100 terminal It gives very extensive control of trans mission mode and display format and includes such features as sto rage of telephone numbers for an auto dialler Communicator costs 59 rom of especial interest to bulletin board users is Pace Sof tware s Commstar 8Kbyte This provides software handshaking file transfer facilities using the Christensen
113. generate convincing vertical pulses which it has not played back The drum servo will use these corrected vertical signals in order to maintain correct drum phase in the presence of head jumping It is important that the off tape field rate should always equal reference field rate therea son for this will become clear when the timebase corrector is discussed Effect of the v t r waveform on video Mixing and editing in PAL video is only possible provided that all Sources are synchronised to within about 5 degrees of subcar rier which is approximately 3 nano seconds field in PAL hasa duration of 20 milliseconds so the stability demanded is 3x10 _ 20 10 1 X 100 0 000015 As mechanism can approach such a tolerance timebase cor rection is mandatory even at nor mal speed Video tape like all magnetic tape has a plastics backing which has a relatively high tem perature coefficient of linear expansion and can also change its dimensions as a function of ambient humidity It is also flexi ble The length of a field track on the tape can be altered by temper ature humidity or tension changes and timing errors will be caused When tapes are interchanged between machines mechanical tolerances on drum diameter and tape tension will change playback timing The impact ofthe rotating heads striking the tape and leav ing again creates shock waves which travel along the tape caus ing jitter Wher
114. generator 0 002HZ to 2MHZ 395 00 TC40 VHF UHF FM and TV field strength meter Battery operated with carry case 177 00 0321 UK PAL TV colour pattern generator 222 60 328 As above but PAL B G H 222 60 DM801 700KHZ to 250MHZ 01 meter Inductlve cap freq measurement etc 62 00 CHART RECDADER 100 2 Panel mount 240V AC 149 00 LFM39 A D Wow and flutter meter Jis CCIA Oln 445 00 HZ65 Scope add on component tester 24 00 LTC910A CRT tester rejuvenator for b w and colour 175 00 Official orders weicome Subject to confirmation ALL MODELS ON DISPLAY OSCILLOSCOPES Full specification any model Send SAE UK C P amp ins Single trace Qual trace carrier 2 60 carrier TNT 5 20 TNT Securicor 10 45 Securicor HAMEG 2 years warranty HM103 Single trace 2 2mV 6 x 7cm display plus component tester 158 00 HM203 Dual trace 20MHZ 2mV Algebraic add 2 Mod plus component tester Optional carry case 21 50 264 00 204 Dual trace 20MHZ sweep delay 2mV plus component tester optional carry case 21 50 365 00 HM605 Dual trace GOMHZ delay line MHZCALGEN optional carry case 21 50 HITACHI A All models 5mV 1mV using x5 magnifier All models complete with 2 probes 2 years warranty V212 Qual 20 2 bench portable 6 CRT CHI 0 335 00 V222 Dual 20MHZ portable with DC of
115. is work ing as head of systems integra tion at the ground checkout and test division of ISRO Satel The authors are with ISRO Satellite Centre Bangalore India except S P Kosta who is studying at the National College Jayanagar Bangalore 25 Fig 2 Probe coupling configuration REFERENCES 1 S P Kosta et al Cypress plant as r f antenna Frequenz April 1979 pp 117 8 S P Kosta et al Date palm tree branches as antenna structure Nachrichten iri ad Zeitschrift NTZ April 1979 p i 2 S P Kosta et al vegetation canopy as antenna structure Communicated to IEEE Transactions on Antennas and Propagation paper C 013 June 1983 3 S P Kosta et al Coconut tree branch nature s television antenna to Proc IEEE September 4 Li Jen Du and W H Peake Rayleigh scattering from leaves Proc IEEE June 1969 pp 1227 9 5 J E Spence and Heisler Jr Radio propagation loss in a tropical jungle Abstracts of URSI 1967 Fall Meeting University of Michigan Ann Arbor 6 Jasik Antenna Engineering Handbook McGraw Hill New York 1961 26 TREE TV located to receive line of sight signals at a distance varying from 12 to 25km from radiating tv tower were used to receive colour as well as black amp white signals A flexible coaxial cable RG 58A U tapped r f energy from the appropriately selected places
116. 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 2 d J A STRUMECH ENGINEERING LIMITED Portland House Coppice Side Brownhills Walsall West Midlands WS8 7EX England Telephone Brownhills 05433 4321 Telex 335243 SEL G CIRCLE 48 FOR FURTHER DETAILS Happy Memories Part type 1 off 25 99 100 up 4116 200 1 25 116 110 4164 200ns 4 onmes 4 95 4 55 4 40 2016 SONS eum secco teens 4 95 4 40 4 20 6116 150ns Low power Call Call 6264 150ns Call Call 2716 450ns 5 volt oio 3 85 3 45 3 30 2732 450ns Intel type 4 75 4 25 4 10 2732 350 5 25 4 69 4 50 2532 450ns Texas type 3 85 3 45 3 30 2764 250ns Call Call 27128 300ns Call Call Z80A CPU 2 99 Z80A P10 2 99 280 2 99 6522 PIA 3 70 7805 0 50 7812 0 50 Low profile IC sockets Pins 8 14 16 1 Pence 12 13 14 8 16 20 22 24 28 40 18 22 24 27 38 Soft sectored floppy discs per 10 in plastic library case 5inch 5550 17 00 5inch SSDD 19 25 5 inch DSDD 21 00 5 inch SSQD 23 95 5 inch 0500 26 35 74LS series TTL large stocks at low prices with DIY discounts starting at a mix of jus
117. of IC and the BRTS input to pin 8 of IC Components The Am7910 integrated circuit is stocked by AMD distributors including Quarndon Electronics and Hawke Electronics the unit price is 32 80 excluding v a t This and other semiconductor devices for the project together with the crystal the relays and the connectors are available from Technomatic Ltd see address list The Am7910 is also stocked by Maplin Electronics The two transformers can be supplied for 5 70 the pair including inland postage and v a t by Barrie Electronics A printed circuit measuring 160 by 200mm will be available from July 10 from Combe Martin Electronics for 16 inclusive The board a prototype of which was shown in last month s article is double sided with plated through holes Software To control the modem a suitable communications program is needed In its simplest form this would configure the serial port to transmit and receive at the required rate It would then route data arriving from the modem to the screen and direct data from the keyboard to the modem In a practical program there would also be facilities for select ing the data word length parity and stop bits for controlling the display format and for transfer ring disc or cassette files to and from the modem by Richard Lambley Vat ues heracomputing ae MICRONET 900 UT e el MCA use 8 Y 23 42
118. or voice grade radio then to a video signal again for display on a monitor at the receiving end The entire process takes as little as 4 seconds and costs only the amount of the phone call Since one more cameras can be fed to one or more monitoring stations for viewing sequentially or simultaneously and since the system can be fully automated there is almost infinite number of PLTV system configurations possible Permanent stor is available by recording the transmissions on cassette tapes For fast uncomplicated inexpensive visual monitor ing of any subject anyplace Robot Phoneline is the answer Write and descriptive literature Robot UK Ltd Building 33 East Midlands Airport T ROBOT RESEARCH INC Tel 0332 812446 Telex 37522 Worid Leaders in Phone Line Television and Image Processing Systems CIRCLE 42 FOR FURTHER DETAILS or for more information Castle Donington Derby 25 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com COMMUNICATIONS COMMENTARY _ CCD camera At NAB RCA introduced a solid state portable broadcast camera based on charged coupled device sensors and a frame transfer process Priced 37 000 the camera is claimed to provide a signal noise ratio of 62dB with high sensitivity and absence of smear on moving objects C c d cameras have been under development for at least ten years but many difficulties have had to be ove
119. playback video The percentage change can be derived from the equation for change in line rate since both are controlled by the same pheno menon Jumping performed in variable speed causes fields to be omitted or repeated which destroys the eight field sequence of PAL The recreation of the eight field sequ ence the correction of the time compression or expansion of fields and restoration of video levels are the major additional actions of a variable speed time base corrector ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com The subcarrier frequency In PAL is thus fixed at 283 times line rate but with offset of 25Hz which causes residual subcarrier on luminance signals to be out of phase on alternate fields helping to make the subcarrier Invisible to the viewer Subcarrier frequency Is defined as 28311 1f 2831 x 3121f f 88672 375f 4 43361875 MHz The V signal can only be decoded properly ifthe recelver knows the sense of the switch This information is conveyed by swinging the burst phase relative to continuous subcarrler from line to line well damped phase locked loop in the receiver will run the average phase of successive bursts but the sense of the phase error inthe loop wil follow the burst swing and will reveal the sense of the V switch to the decoder The swing not be 90 because there would be ambiguit
120. promise as an adjuvant to cancer therapy so far little success has been achieved in heating deep seated tumours A new design of helical coil applicator has been developed which in tests under simulated conditions of the fat muscle bone of a human arm or thigh appears to be both practically and theoretically capable of producing deep heating IEEE Trans 1984 vol BME 31 pp 98 106 and Electronics Letters 1984 vol 20 April 12 pp 337 8 Hyperthermia uses r f power to raise the temperature of tumours to around 43 45 C instead ofthe normal body temperature of about 37 It has been known for over a century that some malignant tumours respond to localized but small elevation of temperature The difficulty has been to heat the affected organ without overheating other parts of the body The Bethesda work has used the industrial scientific and medical frequencies of 13 56 27 12 and 40 69MHz Other workers have concentrated on microwave hyperthermia on 2450 and 915MHz despite its limited depth of penetration of roughly 1cm for loads of high water content such as muscle brain and organs Design of applicators that can improve the heating of tumours deep within layers of fat or bone with minimum absorption of energy elsewhere has proved difficult and the Bethesda work on helical coil applicators appears to be in the nature of a breakthrough A number of British hospitals are involved in hyperthermia experiments some m
121. ranges from multi channel analysers and centrifugal analysers to simple tissue processors and centrifuges You will work with two other technicians repairing and scheduling maintenance of the laboratory equipment This small group also provides a maintenance service to the Medical Physics Department s Nuclear Medicine Radiation Protection and Radiotherapy Sections for their nucleonic counting equipment For this post you will need an HNC or equivalent plus at least four years experience The Sterling salary quoted based on 5 0 Saudi Riyals 1 includes a bonus of one month s salary for each twelve months satisfactory service payable at the end of contract In addition to the tax free salary this two year single status contract post attracts one of the best benefits packages offered in the Middle East For further details and an application form please write quoting Ref P RKH 6653 WW to Kate Vincent Personnel Officer Allied Medical Group 12 18 Grosvenor Gardens London SW1W ODZ Alternatively call our 24 hour answering service on 01 730 5339 quoting reference number All applications will be dealt with in the strictest confidence 2632 TEST EQUIPMENT DESIGN ENGINEERS Rediffusion Consumer Manufacturing design and manufacture a full range of advanced specification colour television receivers and monitors We are looking for experienced Electronic Design Engineers to help us maintain our industry lead in sop
122. requirements with no price penalty WINDING END CAPS 15 VA 50 VA 120 VA 225 500 62 x 34mm 0 35 4 80 x 35mm 0 9Kg 90 x 40mm 1 2Kg 110 x 45mm 2 2Kg 140 x 60mm 4 9 5 Regulation 19 Regulation 13 Regulation 11 Regulation 7 Regulation 4 Why a Toroid 4 SERIES SECONDARY AMS 2 010 6 6 416 4x010 6 6 1000 6 012 938 8 015 25 25 1000 Smaller size amp weight to meet No Volts Current 2x01 942 277 4x011 9 9 6 66 22013 i 20 8 017 30 30 833 modern slimline requirements 4 2 012 12 1 208 4x012 12 12 500 6 0 8x018 35 35 714 00010 6 6 25 2x013 15 15 66 013 15 15 300 6x015 5 8026 40 40 625 Low electrically induced 0x01 9 9 083 2 014 18 1B 38 4 4 18418 333 6x016 450 Bx025 45 45 555 noise demanded by compact 0x012 12412 063 2 015 22 22 13 4 015 22 22 272 6x017 375 8033 50 50 5 00 t 0x013 15 15 050 8 equipment of 99 2 016 25 25 80 4 016 25 25 240 6x018 321 8 042 55 55 454 High effici Ox014 18418 042 2 017 20 30 4x017 30 30 2 00 6x026 281 8 028 110 454 igh efficiency enabling 02018 eee ER 2x028 4 018 35 35 171 65022 250 8 029 220 227 conservative rating whilst main 0 5425 0 2 029 4028 110 109 6x03 8x030 240 2 08 ini 0x017 30 30 025 23030 240 4x029 220 054 6x028 20 dos taining size advantages encased in ABS plastic 80 VA 4x030 240 050 85025 142 5Kg Lower operating temperature VA 90 x 30mm 1 9 160 Regulation 4 arabic 110 x 40mm 1 8Kg 300 VA 9
123. 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 VERBGATE LTD 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 STEWART OF READING 110 WYKEHAM ROAD READING RG6 1PL TEL NO 0734 68041 TOP PRICES PAID FOR ALL TYPES OF SURPLUS TEST EQUIPMENT COMPUTER EQUIPMENT COMPONENTS etc ANY QUANTITY 2616 SURPLUS We offer good prices for test equipment components redundant computers PCB s connectors Immediate settle ment TIMEBASE 94 Alfriston Gardens Sholling Southampton 502 8FU Telephone 0703 431 323 1832 WANTED SURPLUS 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 CAPACITY AVAILABLE TW ELECTRONICS LTD THE PCB ASSEMBLERS More and more companies are investi gating the advantages of using a profes Sonal 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 cle
124. sof tware The standard rom sup plied programs the system for standard timing signals and a dis play consisting of 32 rows of 96 characters each This means that only 32 by 96 or 3Kbytes of v d u memory is required and for the basic system may be omitted 6Kbytes of memory is needed though to work with the higher resolution graph plotting mode provided in Basic which reprograms the 6845 to scan twice as much memory and pro duce a display of 64 rows of 96 characters In graph plotting with the character v d u the split screen plotting area is 192 by 180 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com Connecting a monitor A 30cm screen monitor is about optimum Synchronizing and video signals may be inverted to suit your requirements For the switches controlling the sync signals S44 and S444 on provides negative going syncs whereas switch sections S44 and So select either positive or negative going video note that these two switches must not be on at the same time The dense display makes a stringent requirement on the monitor but standard types with bandwidths of 15MHz or more should be satisfactory As a cheaper alternative a television may be modified This does not stop the set being used as a tv but does require some simple internal At the other end of the pin 6 when 13 44 AIS and bus is in the 8006 to address on the address SPECIAL FEATURE modific
125. sound carrier Overall bandwidth to 30dB of transmitted d p s k signal Level of main sound carrier WWW americanradiohistorv com already been gained in the use of this method Four phase p s k is a digital modulation technique in which the carrier adopts one of four pos sible phase states dependent on the two bit pattern occurring at any instant i e 00 01 11 and 10 Carrier amplitude remains constant except during phase transitions Simple four phase p s k requires the transmission of an additional phase reference signal for correct decoding and this can only be achieved at the expense of increased carrier power or band width neither of which is desir able However if the p s k sig nal is differentially coded d p s k no additional infor mation is required Instead the transmitted message 15 coded into carrier phase changes between one bit pair and the next which the decoder does not need a phase reference to detect Fig 1 Briefly the modulation system works as follows The changes of carrier phase which correspond to the four pos sible bit pairs 00 01 11 and 10 are respectively 0 90 180 and 270 Fig l a The carrier phase itself can dwell in one of four rest states 90 apart as depicted in b input bit pair shifts the carrier phase into a dif ferent rest state by the amount assigned to that particular pair The transmitted phase changes and subsequent carrier rest
126. systems are available but still in the process of development Pye Telecommunications proudly demonstarted their system at Comm 84 which they claim is both complex and reliable It may be used remotely by two way radio or telephone and has been found to work in up to 100dB helicopter noise when test established that only one error resulted amongst 3200 recognitions Some of the techniques used in voice recognition systems were described by Tom Ivallin our last issue Pye Telecommunications Ltd St Andrews Road Cambridge CB4 1DW EWW 218 SOLID STATE BATTERIES Batteries do not often hit the headlines but some new offerings from Chloride are interesting Solid state lead acid batteries use highly absorbent porous separators made from microscopically thin glass fibres that take up the liquid electrolyte within their pores Consequently thereis no free acid and no risk of corrosion ELECTRONICS amp WIRELESS WORLD JULY 1984 conditions there is no loss of water and so it is possible to dispense with normal vents though there is a small safety vent in case of accidental over changing The Powersafe range includes 2V cells of 48 and 110Ah capacities and a 6V block of 80Ah Another range Powerstore is available in 12 different sizes with capacities ranging from 3 to 240Ah in 2 4 6 and 12V configurations Chloride Power Storage PO Box 5 CliftonJunction Swinton Manchester M27 2LR EWW 216 n WWW am
127. that he will find the same standard of arithmetic in all three ranges Precisely so However we have one more obstacle to overcome Calculate the 5 range and you will get two values 1 4 and 1 7 which do not appear in the standard transgressing the no holes rule With them in there was a great deal of overlap while without them the holes are only very small The need to keep the number of values to the minimum was presumably judged to be the over riding factor Even if the poor beast does have bad breath it is still not a bad camel a hard world Alan Watson Pollense Mallorca GPIB COMBINER COMMENTS Irefer to the article in the April 1984 issue of Wireless World by D J Greaves the GPIB combiner Mr Greaves design though ingenious is a complex hardware solution to a problem imposed by his coice of GPIB controller The particular machine he employs the CBM Pet does not implement the full GPIB standard and lacks the ability to pass control The concept of the design is based on a fallacy brought about by the author s reliance on a particular manufacturer s interpretation the function of a GPIB controller Mr Greaves states The main disadvantage of the GPIB busis that only one controller may be connected to the string of peripherals at one time That statement is incorrect The IEEE 488 Standard specifically allows for multiple bus controllers A GPIB controller which implements th
128. to 450M HZ on Harmonica RF 0 1V RMS Int ext 95 00 AF 1KHZ volt 1MHZ Xcal optional 3 00 METERS _ Direct reading LEDmeters DMB013 Pocket 8 range Q 1pf to 2000mld digit 0 5 with battery UK 65 52 13 CM200 Bench model 4 digit 0 2 Ipf to UK 850 89 00 DIGITAL THERMOMETERS Pocket size LCD thermometers complete with battery Accept any type probe UK 65 TH301 LCD 50 C to 750 C 1 C resolution with thermocoupla 59 50 302 100 40 C to 1100 Cent Fahrenheit 0 1 and 1 resolution with thermocouple 79 50 Range of various probes in stock 17 50 to 25 00 COMPONENTS ACCESSORIES TOOLS Large range In stock semiconductors relays tools Plus millions of capacitors resistors presets controls plugs sockets etc etc For bulk export users Tel 01 723 1008 with enquiries OTHER EQUIPMENT IN STOCK Send SAE for full specifications UK C P 1 50 UK 1 00 LH C909 VHS BETA video head tester 45 00 each OM358 gt Scope multiplexer 35MHZ expands any scope to eight channels 169 00 11 905 Scope add on semicon curve tracer 99 00 Transistor tester ali types 4109 00 116907 Transistor tester signal Injector tracer 178 00 LVT72 FET VOM transistor tester 143 00 LCR 40 LCA bridge cap inductance and resistance 195 00 LDM170 Distortion meter 20HZ to 20KH2 310 00 LF61300 Swesp 0 3 functlon
129. to know that it originated from the maker s service sheet and were not shown on the circuit diagram The BC337s of Fig 41 are transistors 653 652 amp 651 inthe text the BF392s are 659 658 amp 657 and resistors 665 664 amp 663 are the 22k pull up components at the BF392 bases Also on that page the resistor referred to in line three column three should be 2 7k and not 2 79 In Fig 42 the annotation Fig 34 should have read Fig 41 The author also asks us to point out that in Fig 40 the chroma input burst should be 150mV rather than the 250mV shown at pin3 of the i c The right hand ordinate on Fig 86 page 62 June was inadvertently cropped and should of course be labelled with attenuation in dB Observant readers will have noticed that Fig 60 was a repeat of Fig 69 the correct figure appears in this article In Fig 24 page 56 January please substitute 200ns for the 20015 shown Component suppliers 1 Surface wave filters Signal Technology Ltd Crompton Road Groundwell Industrial Estate Swindon Wilts Tel 0793 726666 230 Mullard Ltd Torrington Place London WC2 Tel 580 6633 Delay lines Manor Supplies 172 West End Lane London Tel 794 8751 Future Films Leamington Street London W1 Tel 437 1892 Coil formers Ambit 200 N Service Road Brentwood Essex Tel 0277 231616 40 TELEVISION Parts list for Fig 34 36 one line comb filter circuits
130. tv signals before any commercial venture can thought of WWW americanradiohistorv com packing procedure Continued from page 23 inclusion of D 2 forming a clamp at zero volts Capacitors C55 and C are bypass capaci tors to reduce interference from switching spikes r f etc Switch sense points at the junc tions of R and C Fig 1 are each taken to an input of a group of eight to one bit multiplexers IC whose inverting outputs D provide a byte which can be read by the computer through the v i a Control inputs of the multi plexers A B and C aretaken to a three bit counter whose clock input is connected to CB pro grammed as an output of the v i a Capacitor C and Rs pro vide a reset to zero on switch on so that the counter always starts from a known position see flow diagram Thus the whole keyboard is read in eight bytes This gives a complete bit map of the state of the keyboard and some redun dancy After receiving eight clock pulses the counter is back in its original state The delay at the third operation in the flow dia gram is introduced to allow for any residual key bounce and for the fact that it is impossible to play all the notes of a chord simul taneously Figure 2 shows that only six of the eight inputs of IC used and only seven of IC It would be possible to fit a 48 note keyboard using all the inputs of six multi plexers and i
131. um um um CAPITAL APPOINTMENTS LTD 1 THE UK s 1 ELECTRONICS AGENCY nical sales or similar fields Telephone now for our free jobs list We have vacancies In all areas of the UK Salaries to 15 000 pa 01 637 5551 or 01 636 9659 24 hours CAPITAL APPOINTMENTS LTD 29 30 WINDMILL STREET LONDON 1HG 245 am um um If you HNC TEC or higher qualifications and looking for a job in design test customer service tech 8 Allied Medical Group Kx The Best of British Health Care in the Middle East 94 MEDICAL PHYSICS TECHNICAL OFFICER Medical Electronics Saudi Arabia c 14 950 p a inc tax free Allied Medical Group are the British health care consultants to the prestigious 650 bed Riyadh Al Kharj health care programme in Saudi Arabia The two hospitals which comprise the Programme are new superbly equipped mainly U K staffed and enjoy a full range of paramedical and support services The Bio Engineering Section of the Department of Medical Physics and Bio Engineering based in Riyadh is responsible for servicing approximately 2 200 items from a wide range of bio medical equipment We now need an MPTO to specialise in the maintenance ofan extensive range of laboratory equipment covering clinical chemistry haematology microbiology and histopathology The complexity of the equipment
132. which will then replay on one of the dedi cated channels back down through the hub site and the cus tomer s own switching point and out on to the customer s own sec ondary link Local area networks A lan is a communications network connecting a number of ELECTRONICS amp WIRELESS WORLD JULY 1984 Super head end Super primary links Maximum ef Hub site 120 wsp 5 lt ws p wideband switching point up to 300 users sp Primary links users within a local geographical area to shared computing resources The two most com mon topologies have been the contended bus with collision detection Ethernet and the ring structure as in the Cambridge ring Fig 5 Many of the features of optical fibres make them attractive for use in lans but usually only after some modifica tion from a coaxial cable design has been implemented In the Ethernet system each station is connected to the coaxial bus via a bidirectional passive tap making insertion of a new work station a relatively simple matter Each station attempts to transmit its message when the bus is quiet If a message collision is detected transmission 15 stopped and retried a short time later With fibre optic technology it is relatively difficult to make passive couplers without an unnacceptably high loss thus restricting severely the number of users that may be attached to the bus To overcome this Fibernet the optical version
133. with a B Sc and M Sc from University College of North Wales is head of the microprocessor division of Graseby Dynamics Ltd Prior to working in industry he held various educational posts during which he initiated the teaching package Starting microelectronics This his second series of articles for Electronics and Wireless World combines his interests in education and engineering In his spare time John is a 31 MEMDIS Aq VDUSEL SPECIAL FEATURE Address Internal address RD p 55 Buffer 12MHz f Display multiplexer gt 6Kbyte video read write memory blanking Character clock 0v decoder Character row address Paraltet to serial _____ ___ _ Designed chiefly for fast clear high density text display the monochrome v d u section of SC84 is memory mapped and uses the pipelining technique Output is separete video and sync signals in either polarity Fig 1 SC84 s monochrome v d u circuit right uses an enhanced version of the 6845 c r t controller with light pen register and interlaced video facility to give 32 lines of 96 characters and up to 192 by 192 pixels for graphics Using character generator is cheaperthan using a proprietary rom and allows reprogramming Switching is included to relocate the v d u section for experimentation 32 Controller cl
134. 0 8156 745287 200p 7 300p 47028 750 LF357 330p NE555 22p ULN2001A130p 8205 749288 180p 024 325 1 3 4 LF 3331 350b NE556 ULN2002A130p 8212 300p 745387 225p MC4044 325p UARTs ME LM10C 325p NE564 400p ULN2003A130p 8216 200p 745473 475P 14412 750p 3 1015 745 SERIES 74500 100 74502 100 74504 120 LM301A 25 565 150p ULN2004A130p 8224 75107 90 7491 74505 100 307 45 566 150p ULN2068 380p 8226 75110712 180p I ayigata 7492A 45956 74508 100 LM308CN 75 NE567 140p ULN2802 250p 8228 250p 2532 450p 75114 15 160p 300 800p 7493A JALS96 74510 100p 120p NE570 400 ULN2803 250p 8243 400 2532 30 700p 75121 22 140p COM8017 300p 5 583285 SOP 7415107 74511 100p Toate 1505 571 400p ULN2804 250p 8250 1400 2564 700 75150 120p 6402 360p 350p 7415109 74520 100p 319 592 75 575 275p 8251A 1800 2708 400 75154 140p 181602 300p 7258 7418112 74522 100 505 5532 200p UPC592H 200p 8253 5 1800 2716 350p 75159 220 TELETEXT 74100 745113 74830 100 400p 3342 NE3533 160 UPCI 6H 8255 51900 2732 450p 75365 gt 1150p ZIF SKTS DECOD 200 PEST 745332 180p 120p 3
135. 0 WORLD CHIP The chip atthe heart of Richard 5 Multi Standard Order now and ask for your free data sheet 0000 DEVICES IN STOCK AT HAWKE Prime Source for AMD 7910 019797799 AHEAD OF THE ep Hawke Electronics Limited Amotex House 45 Hanworth Road Sunbury on Thames Middlesex Tel 01 979 7799 Telex 923592 WORLDCHIP s a Trade Mark of AMD CIRCLE 52 FOR FURTHER DETAILS 1 5GHz testing problems Use a TECHTEST Model 260 1 5GHz Up Converter it works with any 240 350 MHz generator The Model 260 has been designed to provide a very economical signal source for testing 1 5 GHz communication equipment Itis a linear heterodyne up converter that employs advanced techniques to generate very clean and stable signals in the 1440 1550 MHz band from signal generator inputs 1200 MHz lower Since it has zero insertion loss the input signal generator controls are used directly to set the output signal level and all modulation conditions Full accuracy and stability is ensured by phase locking the internal 1200 MHz local oscillator to the signal generator standard Find out more from Techtest Ltd Street Court Kingsland Leominister Herefordshire HR6 90A England Telephone KINGSLAND 056881 744 Telex 837264 CIRCLE 70 FOR FURTHER DETAILS SATELLITE RECEIVING EQUIPMENT 1 9M 2 5M and 5M Harrison Dishes Sat Tec R50
136. 0 12 2 and 3 respectively so the input resistor may be made from zero one two or three resistors in parallel and the feedback resistor form the same number of resistors in series B P Cowan Bedford College University of London Current limiting for 317 regulators Addition of an opto isolator to a 317 based variable voltage power supply allows precise current limiting I have used this circuit to protect transistors during development of r f output stages of uncertain behaviour and it should be possible to apply this idea to simpler power supplies using power transistor zener diode combinations When voltage across the series pass resistor exceeds around 1V the isolator photodiode starts to emit turning on the phototransistor and reducing control voltage to the regulator Output diodes keep regulator output voltage at CIRCUIT IDEAS 23819 _ All resistors except are yw Load lt 1 5V above control voltage to limit output current under a dead short Power and resistance ratings of the series resistor are chosen to suit the required current limit and the diodes must ELECTRONICS amp WIRELESS WORLD JULY 1984 beableto carry more than the current limit value Lionel Sear Truro Cornwall WwwW americanradiohistorv com Combination lock with deterrent In this idea in the May issue IC should have been a 74148 of IC is not connec
137. 0 40 BC284 030 158 0 22 139 0 40 BC300 0 30 BF160 0 27 AF178 1 95 BC301 0 30 BF167 0 24 AF239 0 42 BC303 0 26 BF173 0 22 AU107 3 50 BC307B 0 09 BF177 0 38 AUT06 3 25 BC327 0 10 BF178 0 26 AUT 0 2 00 BC328 0 10 BF179 0 34 BC107A 0 11 BC337 010 BF180 0 29 1078 0 11 BC338 0 09 BF181 0 29 BC108 010 BC347A 013 182 0 29 0 11 BC461 0 35 BF183 0 29 BCIOBB 0 12 80478 020 BF184 0 28 109 0 10 527 020 185 0 28 BC109B 0 12 BC547 010 BF194 0 11 BC109C 042 BC548 010 195 0 11 114 011 BC549A 0 08 196 0 11 116 0 15 80550 0 08 197 0 11 117 019 557 0 08 198 0 16 119 0 24 BC557B 0 08 199 0 14 125 0 25 80558 0 10 BF200 0 40 BC139 020 160 BF24 015 8C140 031 80115 0 30 245 0 30 BC14 025 0116 0 60 BF256 LC 0 28 142 021 0 2 059 BF257 0 28 143 024 80131 0 42 258 0 28 BC147 0 09 80132 0 42 259 0 28 1478 0 09 80133 0 40 271 0 26 BC148A 0 09 80135 0 30 BF273 013 1488 0 09 80136 0 30 BF336 0 34 8 149 0 09 80137 0 32 337 028 BCIS7 0412 80138 0 30 BF338 032 158 0 09 80139 0 32 BF355 0 37 BC159 009 BDD140 0 30 BF362 0 38 160 0 28 0144 110 8F363 0 38 161 0 28 80159 0 65 71 0 20 8C1708 0 15 8D160 1 50 BF394 0 19 171 0 09 80166 0 55 BF422 032 8 171 0 10 80179 0 72 BF457 0 32 1718 010 80182 0 70 458 0 36 80172 0 10 80201 0 83 8 459 036 8 1728 0 10 80202 0 65 BF467 0 68 BC172C 0 1
138. 0 802023 0 78 8 595 0 23 1738 0 10 BD204 0 70 82597 0 25 BC174 009 80222 0 46 BFR39 023 DIODES BY206 044 IN23WE 2 95 BY 208 800 0 33 IN4001 0 04 2 BY210 800 0 33 144003 0 04 119 9 08 223 9 90 1N4004 0 05 115 913 298 400 0 22 IN4005 0 05 145 016 BY299 800 0 22 4007 0 06 148 017 BYX10 0 20 41488 0 02 154 0 06 BYX36 150R 0 20 IN4448 010 156 0 15 BYX38 600R 0 60 IN5401 012 157 0 30 55 600 0 30 IN5402 014 BAX 3 0 04 BYX71 600 110 IN5403 012 BAXI6 0 06 82 95 30 0 35 IN5406 0 13 BB105B 0 30 CS4B 4 50 IN5407 016 BT151 0 79 5108 845 IN5408 016 BY126 010 OA47 0 09 44 0 04 127 on 90 9 05 77923 015 BY133 0 15 91 0 06 1772002 010 164 0 45 95 0 06 8 176 1 20 04202 010 ee BY179 0 63 IN21DR 2 95 87182 0 55 IN23B 2 95 184 0 35 IN2SC 245 available 199 0 40 2 95 request 78 COMPONENTS LTD SELECTRON HOUSE WROTHAM ROAD 3LINES MEOPHAM GREEN MEOPHAM KENT COMP TELEX 966371 5400 1 35 TDA2524 1 95 5500 195 TDA2530 1 95 560 1 45 TDA2532 195 560 1 45 TDA2540 1 25 560 1 45 TDA2541 2 15 TBAS70 100 TDA2560 2 15 6474122 50 TDA2571 2 95 TBA651R 2 50 TOA2581 225 TBA720A 2 45 TDA2593 2 95 t 7500 2 65 TDA2600 5 50 A1865 20
139. 0 89 TBA231 125 515131 2 30 SN76115N 1 25 TBA395 1 50 M51515L 2 95 SN76131N 1 30 TBA396 0 75 M51521L 1 50 SN762260N 2 95 440 2 55 MB3712 2 00 SN76227N 1 05 4800 1 25 MC1307P 1 00 SN76533N 1 65 TBAS10 250 MC1310P 1 50 SN76544N 1 95 5100 2 50 1327 0 95 SN76570N 1 00 520 110 13270 0 96 SN76650N 1 15 5200 1 10 MC1330P 1 10 SN76660N 0 80 TBA530 110 1349 1 20 51 014 7 95 5300 1 10 1350 1 95 STKOIS 7 95 540 1 25 SEMICONDUCTORS 2222 MU 0225 0 48 12 0 25 BCI 74A 0 09 BC232 0 35 AC 126 0 45 177 0 15 0233 0 35 127 0 20 178 0 15 80234 0 35 128 0 28 182 0 10 80236 0 45 ACI28K 0 32 BC182LB 0 10 BD237 040 141 0 28 BC183 010 80238 0 40 141 0 34 BC183L 0 09 0241 0 40 AC142K 0 30 18418 0 09 BD242 0 50 176 0 22 BC204 010 0246 0 60 ACI76K 0 31 BC207B 0 13 BD376 0 32 187 0 25 2088 0 13 BD410 0 55 ACI87K 0 28 BC212 0 09 BD434 0 55 188 0 25 BC212L 0 09 BD437 0 50 ACIBSK 0 37 BC212LA 0 09 80438 0 60 AD142 0 79 BC213 0 09 BD520 0 65 AD143 0 82 BC213L 0 09 BD538 0 65 AD149 070 BC214 0 09 8D597 0 75 AD161 9 39 BC214C 0 09 80701 1 25 AD162 0 39 2144 0 09 80702 1 25 AD161 2 0 90 2378 0 09 0707 0480 106 0 50 BC238 0 09 BDX32 1 50 AF114 1 95 BC239 0 12 BDY57 1 65 AF121 0 60 BC251A 0 12 BF115 0 35 AF124 0 65 BC252A 0 15 BF119 0 65 AF125 0 35 BC258 025 BF127 0 24 AF126 0 32 BC258A 039 BF154 0 12 127
140. 0 Hz 100 kHz frequency range and switchable output impedances A high 30 Vpp amplitude in the asymmetrical mode with stepped and continuous attenuation a 10 Vpp floating output in the symmetrical mode and useful TTL or DIN loudspeaker outputs are Test amp Measuring Instruments further benefits In addition there is a choice of low distortion or fast settling modes PM6309 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 distortion 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 74 PM 6309 distortion meter 75 Philips Test and Measuring Pye Unicam Ltd York Street Cambridge CB1 2PX Tel 0223 358866 Telex 817331 PHILIPS MBM2732 MBM27C64 3716 2732 MBM27128 2815
141. 0 processor running at 8MHz The SCC 01 can also have up to 32Kbytes of local program stored in eprom or fusible link prom and 128Kbytes of dynamic ram The unit communicates with a host processor through a VME bus by means of interrupt generation and 4Kbytes of dual port ram There aretwelve u a r tsonthe card eight of which are used for several peripherals while the other four are available for monitoring in receive only mode The u a r ts have programmable data rate generation and can detect breaks in a data stream Four of the u a r ts have been designated as fast channel devices and if selected all four can be operated in synchronization at up to 1Mbaud Plug in daughter boards provide conversion from t t 1 level to RS232 RS422 or 20mA level The double Eurocard with the system on board has been designed for use in industrial environments and can operate within a temperature range of 0 to 70 C and a relative humidity of up to 9 All boards undergo a 48h temperature power cycling programme Manufactured by Wormald Data Systems they may be obtained from Unit C Ltd Dominion Way West Broadwater Worthing West Sussex EWW 222 FORTH EPROM PROGRAMMER Asingle Eurocard accommodates a circuit which can be used to program read verify and copy eproms The TDS960 card is used in conjunction with the single board TDS 900 Forth computer and the programmer software is provided on rom as well as a listing The Forth
142. 00 PDSoo 6 00 30 00 7 1040 19 6AM6 6 02 6 250 75C1 4 50 6080 14 00 DET22 35 00 ECC82 1 75 EL822 13 97 1 6 50 PEO6 40N 45 00 TT22 37 50 2 1041 16 66 6ANS 4 75 6N7 3 0 85 1 7 50 6097A 235 00 DET24 49 00 ECCH 1 75 EM34 5 00 842 8 75 PFL200 2 50 TTI100 60 00 2 1042 17 7 3 50 6P25 4 00 8542 4 45 6097B 200 00 DF91 3 75 1 75 EM80 2 50 M8144 7 50 PL36 2 50 TY2125 65 00 1 3 00 6AQS 225 607 3 75 90AG 12 96 6146A 8 25 DF 175 ECCSS 1 75 150 M8149 6 50 125 4 400 75 00 1824 25 0 6 56 8 66 6R7 325 12 6146B 8125 DK91 1 75 ECC8 2 50 EM84 100 M8161 935 PLSIA 2 00 4 500 98 35 IB3SA 48 00 GAS7G 875 6SA7 3 0 90CI 6 00 61598 19 00 DK92 2 0 ECC88 210 85 275 M8162 10 40 PL82 1 50 TYS 500 201 50 1863 64 00 6 6 1 25 65 7 275 9 CG 1454 6189 9 50 DK96 1 55 2 00 150 8163 8 25 PL83 2 50 6 800 196 50 IRS 1 75 6AUSGT 5 00 6SF7 2 50 CV 1545 6201 11 40 DL92 19 ECC9 8 93 EN32 17 46 M8190 5 00 200 6 5000 155 1 75 6AU6 2 50 6SH7 3 00 92AG 15 50 6442 20 00 DL94 1 75 ECCIS9 2 10 EN9 7 05 M8195 10 85 PLSO45 2 50 490 114 1 75 6AVSGA 4 50 657 3 25 92AV 12 96 68838 8 25 01 96 1 75 ECC807 1 75 RE 74 PL0 2 26 Y63000 24815 150 ESK 3 50 522 1o 01510 1400 EC
143. 00 4GHz Receivers COM 2B 4GHz Receivers California Amplifier 4GHz LNAs Chaparral Horns Harrison Feed Horns Demonstrations by appointment only Dealer enquiries welcome For further details contact Harrison Electronics 22 Milton Road Westcliff on Sea Essex 550 7JX Telephone Southend 0702 332338 CIRCLE 6 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com MULTI STANDARD MODEM ulti standard modem Details of the line interface and software requirements plus some telephone numbers to dial The line interface follows the pat tern shown in Fig 3 of the article in the May issue In the direct connect version of the modem IC duplexes the trans mitted and received carriers Resistor R is the terminating resistor for the telephone line A cmos analogue switch IC pro vides loopback of the transmitted signal to the receiver input when S is in test position but in a direct connect modem this i c and its associated components Tr and Tr etc should be omit ted since there will be sufficient coupling around the duplexer If IC is not fitted a link must be wired between pins 8 and 9 of its location on the p c b When a call is in progress the modem holds the telephone line by means of the gyrator network around Tr and Tr This arrange ment is taken from a Mullard cir cuit widely used in commercial modems heat sink 15 requ
144. 00 V8010A 65 00 BU124 1 25 M3708 012 D14 173GM 53 00 311826 53 00 1 1 15 00 BU125 125 2M373 9012 D14 173GR 55 00 M31 183W 55 00 1 1 15 00 80126 16 cheese 7203 D14 181GH 62 65 00 M31 184W 65 00 28P1 9 00 Buzo 1 284280 350 D14 181GH 98 65 00 M31 184GH 65 00 3BP1 13 50 80208 139 254427 150 014 1816 55 00 M31 184P31 65 00 4EP1 30 00 2 284422 D14 181GM 53 00 M31 185GH VR 69 00 3H 0BM 55 00 152 245204 0 42 14 1816 50 59 00 M31 186W 69 00 58m 9 00 BU208D 1 85 2N5296 048 14 181 55 00 M31 190GH 55 00 5 1 30 00 80326 1 20 248298 0 60 014 1826 59 00 M31 190GR 55 00 SBHP1FF 30 00 80407 1 24 235496 065 014 1826 98 65 00 M31 190LA 55 00 5BHP31 30 00 BUSO0 225 22442 060 D14 200BE 89 00 M31 190W 59 00 5 1 10 00 80528 2230 0180 D14 200GA 50 85 00 M31 191GH 59 00 7 39 00 BUB0v 225 256495 0 80 D14 200GM 75 00 M31 191GR 59 00 138P1 13 50 0 698 1 70 2561095 080 D14 210GH 75 00 M31 191GV 55 00 13 4 17 50 Mj3000 1 98 250 614 2706 50 75 00 M31 191W 59 00 170 4 25 00 MJE340 0 40 SCHT2Y 220 D14 310W 110 00 M31 192W 59 00 32J 1085 69 00 520 0 48 2561173 115 D14 320GH 85 00 M31 195GH 59 00 88D 15 00 MPSAIS 029 25 i306 100 D14 320GH 82 85 00 M31 210GH 59 00 89B 15 00 MPSAS2 030 2561307 150 D14 340GH KM 45 00 M31 220W 59 00 890 15 00 237 552135 020 D14 340KA 45 00 M31 270GY 65 00 8 15 00 MRF450A 1250 2561449 080 D16
145. 02 2900 government 6655 250 12AT7WA 2 50 708A 800 ANT 1400 0 65 695 KT77GoldLion 5 83 5952 130 _ 5 95 XR1 1600A 1250 6 18 250 12406 150 715A 6 00 ARPI2 0 70 EBF83 0 65 635 350 84 9 78 Sci 800 5 00 49 50 4CX250B 6 4 060 12AU7 055 7150 4500 ARP34 1 25 EBF85 0 95 095 709 5 88 100 SCi 1200 5 00 XR1 3200A tested ex 6 7 350 12AV6 080 725A 27500 ARP35 200 EBre9 070 184 aso 9 00 5195 175 561 2000 9 00 79 50 equipment 6 86 195 12 46 1 00 803 14 95 8163 2 00 EBF99 0 Figs 0 85 50302 100 Speooom XR1 6400A 6 00 6CD6GA 4 50 12 7 0 65 805 39 00 85450 67 00 EBLI 250 186 ED 1595 345 1250 45 00 99 50 4CX250BM 6CF6 150 12AX7WA 2 50 807 1 60 BSB 55000 200 600 krere 900 220 1 gp 150 v63 150 EIMAC 75 00 66 6 635 12AY7 3 95 810 4500 8540 ECS2 075 ELBI 600 K767 300 Pisos 16 Son 50 v ess aCX2S0K 6CL6 325 12 2 195 1295 19 00 7 175 552 1215 KTW62 250 5 208 1 5 Spa2 300 Y602 1200 9500 6CL8A 200 12844 350 813 18 50 2140 95 350 KTW63 200 5209 485 55501 3500 01100 7500 4CX350A 7150 6CM5 160 12846 150 BI3USA 45 00 1108 54 95 7 95 350 KTZ63 250 59 435 sm 150 YJ1060 265 00 4026 75 00 6656 075 1
146. 08 2N2907 021 234400 011 87 0 28 BCIO8 0 16 327 0 12 016 BFYS2 0 25 MPSUO6 0 65 72 100 TIP4A 042 15921 09 2N2924 0 26 011 ACI88 0 28 9 016 BC328 012 pFjs3 016 BFY64 0 30 MPSUS6 0 69 1 00 2955 070 26301 100 242925 022 ol 130 0 15 BC337 0 12 gFis4 047 BFY90 0 95 NESSS 0 45 0 70 TIP3055 0 6 26302 1 00 2N2926 0 15 2N5457 032 ACYI8 1 15 BCll4 015 BC38 0 12 BFI59 017 BSXI9 027 NKT401 3 50 0 75 0 65 043 2G306 140 2N3053 026 2NS458 032 ACYI9 110 BCIIS 0 18 BCY30 1 25 017 BSX20 0 27 NKT403 250 OC76 1 00 25140 0 25 2N404 130 2N3054 0 55 2NS459 0 32 ACY20 1 10 6 0 19 BCY31 150 0 24 BSX2 0 29 NKT404 220 1 00 25170 021 2N696 0 32 2N3055 065 25017 10 00 115 7 0 23 BCY3 150 0 30 BT106 120 OAS 1 20 0 81 0 65 25178 054 24697 0 32 243440 0 70 25019 1200 ACY39 2 50 BCll8 0 18 BCY33 110 0 35 BTY79 400R 0 60 OCHZ 1 20 25271 0 23 2N698 032 2N3M4l 0 85 2506 250 ADI49 0 75 125 018 1 00 BFI78 0 35 2 00 0 55 OC82 0 0 75278 0 57 2N705 1 25 23442 1 25 25103 1 50 ADI61 0 35 26 018 BCY39 3 40 BFI79 0 35 BU25 1 30 47 0 12 10 ZTX107 0 12 2N706 0 25 2N3614 220 25302 200 ADI62 035 BCI35 015 BCY4 280 0 28 BU26 15 OA70 025
147. 0MHz 4 watts an 84 50 3 50 p amp p TYPES ED 140 00 8 00 p amp p TYPE 9002 Two stage preamplifier N F 0 7dB Gain 25 dB High Q filter 285 2 p amp p 5 above with integral power supply unit TYPE 9004 UHF two stage Gasfet preamplifier N F 0 688 Gain 2538 Aligned to your specified e 00p amp p frequency in the range 250 500MHz High Q 9174 15MHz 200MHz 20 watts 180 00 8 00 p amp p fie 9 3 Pete es 85 2 p amp p TYPE 9175 As above with integralln mains power supply unit 9012 Gasfet preamplifier mains power supply unit 224 50 3p amp p I SADIPS 240 00 15 00 p amp p TYPE 9010 Masthead weatherproof unit p 26 50 2 p amp p TYPE 9152 TYPE 9159 TELEVISION LINEAR POWER AMPLIFIERS Tuned to your specified channels in bands IV or V or 400 900MHz TYPE 9061 150 mV input 10mW output 2120 25 9152 10 mW input 500 mW output E 160 5 gt 9159 500 mW input 5 watts output 180 5 amp TYPE 9006 _ 9035 GASFET RF PREAMPLIFIERS Aligned to your specified Bondi inthe range 30 250MHz Masthead or local use 9006 0 688 Gain 10 40dB variable e 65 00 2 p amp p TYPE 9006FM As above 01188 108 2 X 65 00 2 p amp p TYPE 9035 Mains power supply unit for above ty
148. 1 when the input amplitude is cor rectly adjusted distortion meter is the only proper way of achieving the minimum distortion figure but visual inspection using an oscilloscope can produce a good enough result A variable or fixed attenuator is used to reduce the sinewave output voltage to a level suitable for recording on the cassette deck s record playback electronics The circuit of the f s k demodulator is shown in Fig 7 the heart of which is the 565 phase locked loop There is noth ing unusual about its design but a few comments will be made so that 15 operation may under stood The phase locked loop consists of a voltage controlled oscillator an identical v c o to that used in the 566 i c a phase sensitive detector and an amplifier with a single stage of low pass filtering The intercon nection between the various ele ments of the 1 1 is shown in Fig 8 When the frequency of the v c o is locked to that of the incoming signal the output from the phase detector amplified and filtered applied to the input of the 0 is that voltage which the 0 requires to produce the particular frequency The voltage applied to the input ofthe v c o is also the demodulated output sig nal that we require For the v c o to produce a different frequency output the voltage on its input will have to change This is exactly what the 1 1 achieves when a signal of a different fre quency is applied
149. 1005 TDA10 0A TOA1022 TOA2002 2003 TDA2020 TDA2030 7000 71061 TLO62 TLO64 TLO71 TLO72 1074 74081 TLOB2 084 UAA170 UAA180 ULN2003 UPC575C2 UPC1156 UPC1156H UPC1182 UPC1185 UPC2002 XR2206 2 409 ZN1034 Ali 240V Primary Split Bobbin 100 6 0 6 110p 9 0 9 1 20p 12 0 12 137p 15 0 15 145p 1A as above 295p 20020 0 125 12012 50VA 595p 12 0 12V 100VA 9 95p 0 6 6 9 9 1 25 4 95 These goods heavy send extra p amp p We will credit any difference 2 95 0 17 COPPER TRACKS 25 3 75 95 25 5 1 08 3 75 3 75 1 09 375 5 1 23 25 17 3 27 375 7 429p 479 17 599p VOBoerd 2 10 DIP Board 3 95 Track Cutter 1 63p Pin insertor 221 100 Pins Verobloc 466p Vero Wiring Pen amp Spoot 3 39p Spare Spoo 75p Combs 6p FERRIC CHLORIDE Quick dissolving Enough to make over 1 tre 1 69 ETCH RESIST TRANSFERS 1 Thin lines 2 Thick lines 3 Thin bends 4 Thick bends 5 DIL pads 6 Transistor pads 7 Dots amp holes 80 1 edge connectors 9 Any sheet of above 35 GRADE ONE GLASS SINGLE SIDED 178 240mm 1 500 420 gt 195mm 1 95 420 245mm 2 950 DALO ETCH RESIST PEN sparenib 1 20p PHOTO SENSITIVE 151 Class Epoxy Glass for better results than spraying expose to UV Single sided 100 160 233 220 520p Double sided 100 160 2 20 100 200 280p 203 x 114 220p 233 gt
150. 100GH 65 00 M31 271P31 65 00 1273 39 00 MEA 2561678 125 D16 100GH 65 69 00 M31 271GW 65 00 1564 39 00 eo 2561909 145 D16 100GH 67 65 00 M31 271W 65 00 1844 45 00 MRF475 2 50 2861945 265 016 1006 67 75 00 M36 12W 75 00 55451GM 75 00 MRF477 10 00 2561953 095 D16 100GH 79 69 00 M36 141LA 75 00 9442E1 80 00 250 5564957 080 D16 100GH 79A 75 00 M36 141LG 75 00 95447GM 75 00 0C23 D16 100GH97 65 00 M36 141W 75 00 95449GM 75 00 OC42 0 55 2502028 115 D18 130GH 65 00 M36 170LG 75 00 7709631 78 50 OC44 0 75 2562029 135 D18 1300GH 70 69 00 M38 100GR 65 00 0 45 0 55 5502058 145 D18 160GH 69 00 M38 101GH 65 00 70 0 45 222091 085 D21 10GH 65 00 M38 103GR 65 00 ocn 0 55 25 2098 250 621 106 59 00 M38 113GH 65 00 OC81 050 225292 135 021 1010 69 00 M38 120W 65 00 820088 170 552314 080 D21 102GH 65 00 M38 120WA 65 00 820108 170 226234 5 50 087 6 35 00 M38 121GR 65 00 R2322 0 58 225454 050 DG7 32 45 00 M38 121GHR 66 00 82323 066 2525 195 0613 2 45 00 M3B I21LA 65 00 R2540 248 0 70 DH3 91 45 00 M38 121WA 65 00 REA enna eaS 135 8 056 DH7 11 95 00 M38 122GH 65 00 SKESF 145 APT RC LINE OUTPUT TRANSFORMERS EHT MULTIPLIERS VARICAP TUNERS PUSH BUTTON UNITS EC DECCA 100 7 95 ITT 20 6 35 ELC1043 05 MULLARD 8 65 DECCA 1700 MONO 9 95 CVC30 6 35 ELC1043 06 MULLARD 8 65 WAY 3039 DECCA 1730 8 95 PHILIPS GB 550 6 96 U321 8 25 PHILIPS 68 550 6 WAY 14
151. 17 UK 30 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 1BOmA Requires 2 magnetic earpieces 2 switches 2 LEOs and connectors to complete Circuits 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 adaptors and the above acoustic modems Integral Line select and autodial relays requiring TTL inputs Circuits and connection data supplied LTU 11 Coupler 13 00 1200 receive 75 BAUO send direct coupled modem for 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 Olsk Drives Boxed Chassis also Winchester Monitors Green Orange White Colour Micro s BBC Electron Nascom Galaxy Plus others Cables plugs blank disks amp tapes software books etc Official orders welcome Subject to confirmation Please add 15 VAT HENRY 5 COMPUTER SHOP 404 406 Edgware Road London W2 Export orders allow adequate CIF 01 402 6822 ORDER BY POST OR PHONE ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com Detalls avallable most models send
152. 172 40 8 967 190 900VA 196 69 5 10 11 200 1 338 40 6 12 1352 200 2KVA 594 50 8 16 1810 226 957 73 10 20 2088 226 4KVA 1266 00 2 24 2320 250 153100 15 20 2660 200 SKVA 2 1743 00 2 40 483 25 2073 00 AUTOS 10KVA 3347 00 105 115 220 230 240V AVOs amp MEGGERs For step up or down 8 latest 140 70 VA Price 73 78 90 80 4 84 140 52 00 150 6 48 1 60 DA212LCD 98 60 350 11 84 200 DA116LCD 154 50 500 1330 224 DA117 Autorange 1000 24 14 2 80 LCD 157 00 1500 2817 320 Megger Gen 116 40 2000 4214 400 Batt Megger 85 50 3000 71 64 480 AVO 2001 91 60 5000 108 30 0 P amp P 2 15 CASED AUTOS 240V to 115V USA BURGLAR ALARM Price Ultrasonic looks likea 20 121 150 Speaker 99 00 150 1828 180 ELECTROSHL TRAS RESISTORS 1 100 250 14 73 2 00 12 33 47 50 2414 270 12 20 33 47 75 390 430 5100 560 1k 1kt 1k3 1000 3274 280 Wc ikB 2k 3k 3k9 15k 2000 60 47 450 7 16k 24k 27k 39k 56k SPECIAL OFFERS 82k 100 110 120k PriceP amp P 130k 150k 200k 220k 100V line to 270k 300k P amp P 20p 4Q10W 3 00 90 25 0 25V BRIDGE RECTIFIERS 3Aor50V6A 7 00 1 50 400V1A 32 PLEASEADO 15 200 2 AS ITEMS 100V 35 2 66 500 12 5 3 40 BARRIE ELECTRONICS LTD Unit 211 Strattord Workshops
153. 1984 272 Www americanradiohistorv com style keypad for rapid frequency selection The display may incor porate extra features such as a bar graph meter to indicate trans mitted power and received signal strength In mains powered sets or mobile equipment designed to run from a car battery a fluores cent display is sometimes fitted this may give better readibility under unfavourable lighting con ditions The transmitter The maximum power level per mitted to British amateurs on the 2m band other than those with special dispensation from the licensing authority is a carrier power supplied to the aerial of 20dBW or in the s s b mode a peak envelope power p e p of 26dBW These figures corre spond to 100W and 400W respectively The power output of the aver age 2m mobile f m transceiver is in the region of 10W Since this type of set is probably the most common there is little point choosing something more power ful unless the performance of its receiver is better than average There is no virtue in being able to shout at other stations if their replies are going to be lost in noise With portable and hand held transceivers transmit power is usually restricted to a watt or two for reasons of battery life but often the power can be switched to a still lower level for contacts under good signal conditions with a dramatic reduction in bat tery drain Under typical condi tions with one minute transmi
154. 2 interface 180CPS Bidirectional printing Dot matrix 7X9 True descenders Buf fered Various baud rates Variable tracktor set tings Ideal for users requiring fast continuous printing Cables and plugs included 80 Phone Crowthorne 0344 776894 2610 VIDEO amp TV TEST EQUIPMENT PAL PHILIPS LDH6200 14 colour monitor 750 PM5519 pattern generator 2500 SYSTEM VIDEO 1204A amp 1205 waveform amp colour 2100 analysers 1 untt DIGITEL D4060 01 noise meter 480 All 18mths old For details write phone 64 Castellain Road London W9 1EX tel 01 289 3533 2636 VALVES PROJECTOR Lamps 6000 types list 75p world wide export Cox Radio Sussex Ltd The Parade East Wittering Sussex Phone 024 366 2023 1991 102 V D US FOR SALE Data General DGC 6012 RS232 V24 current loop 110 4800 baud Qwerty and numeric keypad ideal for interfacing with mic ros useful in test equipment Give away prices 70 125 Phone 01 866 2871 2611 WAVEGUIDE Flanges and Dishes All stan dard sizes and alloys new material only from stock Special sizes to order Call Earth Stations 01 228 7876 22 Howie Street London SW11 4AR 2099 When replying to classified advertisements readersare recommended to take steps to protect their interests before sending money 2519 WANTED Test equipment receivers valves transmitters com ponents cable and electronic
155. 21 422 o 8921 14207 8902 APZI ANZ 0 04125 0 1620 0 gpzr areo 8 02 4190 0 4921 42 8902 82924 Any 0 8901 4162 2 2 2 2 284 284 284 q 284 284 284 220 220 2 2 j9 aeq JPG 29 eq 2 29 15095 29185 xy 59 sont sony sont pat p Jon par par 2011 PI pet pat pot pot sont PIT pot pat pat p 414 44 9 q 01 Ax z 01 01 W 01 0i 429 429 e d apos 52120 510 1825 p n p p n p p n p p p n p p n pedy p n p p n p p n p p n p p n p p n p p n p qouy 081 butuni Yes ZHAG T 7H00Z 02 1916 1 116 1 29450 5 162 5 21 191 180014 62 51 56 45 2 001 ZHAG 152 5 21 ZHAG 1 401 5 ZHAOT S ZHOOTK 2915 1521 6 1521 5 152 621 THAS THAGZ S 5 THAOT S TW301 6 THAOT S ZHAG dais wj Ju 01 8202 S 001 S 1270 WOT AKEZ 5 1 02 AS SZ 8204 5 57 5 MG 52 12 57 1 07 NG GZ NG
156. 21050 Jatjt dwe suabsey9 59215 9844 UI 4320 yaed 226614 2800 20 jaspeau TRANSCEIVER SURVEYS saabseyd 0 321047 318 yaspeay 218 460241 51 2 PIN 5 0 ues 10013 uotsaa pazisauiuAS 06893 0 paztsauiu S sPJjxa 20010 470 X1 a Qgu23 14S 50 uotjeJado purg ssou3 61 s d w s peusaqur 5911621 asn sutes Joj 23118395 12001390 apos 613 5547455 peusaqur Sauinbas asn sutew 104 50 OMJ 50 sdweaJjd syeg 50 OMJ 50 50 OM jn 0 uotsjaA Jawod ubtp 50 OMJ SO A 28002 Jayeads ajejedas 50 dwe 3 yay 5979 euuajue 2140258 9 s0 j OMJ 50 j OMJ 319 8322086 1224 PIN 1 50 OM 50815 PES THAT 04 yndyno 4 4 MG saath Apddns 48751 Ayddns AZ indino apos peng 05 14 3113 p s 5979 5 990 7280807 qpuejs uo 9002 5821 128 p IN 12901360 ST jndjno 218 40 122095 edeo 23545 314 Ajaqeuedas 1 01 5 2 o PU b b 1 Ez 8 1 11 1 d Sp
157. 220 590p Developer for above do not use Sodium Hydroxide 500m 2 95p PRICES PER METRE Solid connecting wire MAINS SPE AKER Twin 14 3 13 Amp 66p SCREENED Single Stereo 27 Mini Single 12 Min Stereo 15 4 Core 4 screens 4 Core single screen 8 Core 12 Heavy Mike Guitar Lead 25p AERIAL 5011 RG58A 75 1 7511 VHF 30011 Flat RAINBOW RIBBON Prices per foot 10 way 16 way RECHARGE BATTERIES Top quality Don t throw these batteries away they charge up to 1000 times HP2 1 2AH 2 39p 2 4 75 99p 11 12 2 29p PP3 110mAH 4 95pj Chargers Adjusted to 6 of As above but faster charge tor HP7IUp to 4 at a time 5 85p SOLDER ANTEX SOLO ERING IRONS 240 15 5 20 52401 25 5 40 iron Stand 75 Elements State Iron 2 05 C240 Bits No2 Smail 03 Med Micro XS240 X25 950 Small 85p 51 Med 5 52 Lge 85 SOLDER 1259715 18swg 2 95p 22swg 310p PLUGS amp SOCKETS D Connectors 25 Way Solder Male 1 60 Female 209p Wire Wrap 1 60 Female 209p Covers 1 00 Phono plugs Bik Red Grn Wt or Yell Line Shis Chas Skt 1 Dua Skt Quad Skt TOGGLE MINI SPST 59 65p 5684 Micro computer The third module of John Adams disc based professional microcomputer for en
158. 23 6EB ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com R F Electronics Engineer An electronics engineer with qualific ations to degree or H N C standards is required to develop radio frequency accessories associated with Nuclear Magnetic Resonance instruments working at up to 500 MHz The ability to contribute to software developments connected with the same instruments will be of added value Appropriate experience demonstrating the ability to progress the hardware develop ments unassisted will be expected Nuclear Magnetic Resonance is an important and growing scientific and medical technique and this two year appointment offers an opportunity to gain valuable experience in this area The appointment will be at up to 8530 p a depending on experience Further particulars from and written applications with the names of two ref erees to Dr A E Derome Dyson Perrins Laboratory South Parks Road Oxford OX1 3QY Tel Oxford 59601 ext 203 2633 98 Appointments Electronics Technician Move up with the award winners Our winning of the Queens Award for Technology 1984 is just one example of our outstanding success The company has an enviable reputation in the marketplace and this is reflected in the calibre of staff we recruit The Special Products Division designs and builds special purpose machines
159. 25 00c PAPER Fanfold 2000 sheets 613506 KAGA Vision 12 RGB Super Hi Computer Grade Cassette 1008 A PH sette interface Softy II 2169 b Adap Ribbon MXBO RX80 FX80 6 50c Res 358 00a Phillips Mini data cassette f tor for 2764 2564 25 00 c 12 Green Hi Res 106 00a SANYO DM8112CX 12 Green Hi Res 299 SMARTMOUTH UV ERASERS PRODUCTION PROGRAMMER The original infinite speech Still the best UV1T Eraser with built in timer and mains P8000 EP 8000 A ready built totally self contained speech synthesiser unit attract inci ilt ively packaged with built in speaker AUX output socket eic n avoid P8000 provides reliable gang pro This CPU controlled Emulator Pro installation problems It allows the creation of any English word with accidental exposure to the harmful UV rays gramming of up to 8 EPROMS simul grammer is a powerful tool for both both ease and simpiicity while at the same time being very econom ical in memory usage You can easily add speech to most existing programs Due to its remarkable infinite vocabulary its uses spread throughout the whole spectrum of computer applications these include industrial commercial educational scientific recreational etc No specialist installation no need to open your computer sim ply plugs into the user port and due to the simple software no ROMS are needed SMARTMOUTH is suppl
160. 270 350p 51601 12 2114 21 500 iCs 8721 20 3278 159 7426 60 jj S08 100p 7425290 140p CA3130T 110 LM1886 500p 940 175p TMS99801200p 2114 41 400p FD 791 422 40 150p 7427 60 74 509 7415393 200p CA3140E 60p LM1889 350p TDA1004A500p 59995 12 2147 450 AD558CJ 775p 01793 23 4194 200 7428 74LS395A 1405 CA3140T 110 LM2917 250p 1010 250p WD55 1450 40273 300 AD561J 20 501795 28 443 125 7430 1909 7415309 2102 CA3160E 100 LM3302 75 1022 500p 28 24 41615 200b 25510 350p rD1797 428 4608 250 7432 745800 20 1806 CA3161E 150p 3900 50 TDA1024 120 280 300p 4116 20 175 25152521 59909 12 49152 250p 7433 60 741513 75 7415465 162 450p LM3909 120p 1170 300p 2804 4118 3 500 350p WD2793 4200 50 175 7437 60 74514 120p 7415467 CA3189E 300p LM3911 160p TOA2002 325p 2808 41642 450p AM26LS31 WD2797 4200p 60 150p 7438 100p 74515 7405490 240 120 LM3914 350p TDA2003 325p 1500p 160p 01691 1500p 6144 175p 7439 50p CA3280G 225p LM3915 350p 2004 300p 4416 15 500p 261532 WD2143 800 74LS20 7415540 70 150 7440 P 744521 605 7443541 D7002 600p 1 3916 350p TDA2006 350p 4532 20 250 160 7 168 125 7441 120 TDA2020 320 4816
161. 2866 1 05 8298 14 50 21126 7000 6 100 E 575 163 150 51802 5 95 5 2 0 Yl1020 29 00 4657 2 25 6CW4 650 I2BH7A 250 833A 6000 C134 3200 100 EL360 6 163 150 350 11020 2300 4GV7 225 5 100 12806 175 Soo 115 00 90 110 EL500 140 8 95 21820 245 14800 2600 6DCe 128Y7A 205 354 2390 1149 1 130 00 EC91 550 509 525 18720 9500 55557 29 50 19 95 277 120 4JC6A 2 95 6DK6 115 12CX6 120 873 60 00 1150 1 135 00 EC92 125 59 6935 598 695 960 sua 495 73020 1200 4 150 25 00 6005 335 12E 17 95 884 5 50 3200 1 6 1598 4645 pyas oso SUM2 2004 23022 1200 renee 1250 arid 400 8 30 2 60 95 7 00 850 s on 070 85 00 25055 15 00 5A152M 9 00 6EAB 2 50 12GN7 3 95 931A 13 95 Cesk 140 12 Ms37A 60 00 5782 9 70 782 300 45 00 Z520M 400 5A163K 10 00 6 88 175 12867 450 954 100 CL33 200 1200 298 46000 070 2520 406 ees heEUS Ens 12HG7 450 2 159 CVNosPrices ECC32 350 200 M Mds 15000 275 00 7000 300 5A 180M 400 6EW6 150 12J7GT 0 70 958A 100 onrequest ECC33 350 70 M8082 750 500 195 2749 0 60 5A 206K 10 00 6 1 2 00 12K5 1 00 1299A 0 60
162. 3 pp 493 9 5 A L Harmer Review of optical fibre sensors IEE Colloquium on Optical Fibre Sensors digest 1982 60 paper 1 1 Lon don 1982 S Sense T Transmit municate with each other At higher data rates such as can be supported on fibre optics the efficiency of a message con tention scheme starts to fall rapidly The transmission delay is not deterministic and the network cannot guarantee to support real time transmission such as tele phony The alternative is a ring network This structure suits the nature of fibre optics better because it is essentially a series of point to point transmissions Since the signal is regenerated at each station there is little trouble with power levels To increase the reliability of communications with respect to fibre failure for example a double ring may be easily employed While commercial versions of optical ring lans are available development attention is focus ing more on structures such as D Net where high data rates and low delays are obtainable Fig 6 shows an outline of D Net in its star coupled form with a single star connector at the far end ofthe outward bound bus The trans mitter T sends regular locomo tive header signals out along the highway which are detected by all stations at their S terminal At each station a message packet may be attached to the appropri ately numbered wagon slot after the locomotive has passed Because the locomo
163. 342 90 NE5534P 120p UPC118511 350p 8256 36 2732 2 900p 7545 2 72 ECODER To 7415122 74537 180p 45 1 332 405 5534 200p xR210 400 8257C 5 750 2732 35 550p 75453 4 72 TEXTOOL SAA5020 600 74 5123 200p 74551 150 160 M348 65p PLLO2A 500p XR2206 400 82590 5 750 2764 25 8900 7549 2 65 24pin 575 SAA5030 700p Er 7415124 629300 74974 120 75 608 RC4136 60p XR2211 575 8279 750p 27128 25 2500p 8726 120p 28pin 800p SAA5041 16 74116 2281252 90 14566 eon LM377 225p SAA 1900 3005 p one 2200p MI ee 74118 74LS126 90 P M380 75 14 74119 748132 sop 74515 1209 1305 CMBBIAN 180 9401004 Naze 1 07 5 TI WIRE WRAP SOCKETS BY TI 74120 745114 120p 130p L cd ZNA24E 13 74121 7415126 75 9p 18 16 24pn 24 8 30 8pin 50 24 75 dm alo me Le um 4 VOLTAGE REGULATORS SIS m uc mis send dins dp mer te 74123 213149 745133 100 75 FIXED PLASTIC 2 427 600p 22 22 40 30 16 45 22pin 75 40 130 14125 7405147 220 745138 180p 75 2 428 450 72126 7415148 220 745139 180 75 sy 7805 50 7905 45 2 429 210 80 1 32 TIP31C 45 2N2906A 3N128 20 TURNED PI 74128 7415161 1006 749140 100p 125 6 7806 7906 45
164. 366 7415367 7415368 7415373 7405374 7415378 7415386 7415390 7415393 7415395 7415396 2415398 74 5399 7415445 74 5490 7415540 7415541 7415640 7415641 CPUs 1802 8 49 6502 3 99p 6502A 649p 6800 275 6802 2990 6809 995p 8035 545p 8039 5 45 8080A 355p 8085 945p Z80A CPU 359p 2808 CPU 945p MEMORIES 2114 pis ask 2532 425p 2564 6 85 2708 3 95 2716 5v 345 2764 8 99 4116 ask 4118 439 4164 6116 6810 MISC LOGIC IC s 4 pis ask 816 pis ask 17 pis ask 1 451771 ask RO2513LC 7 50p RO25 3UC 7 502 5000 405p SAASO10 781 50 2 78 SAA5020 595 SAAS030 6 99 5040 15 95p 5041 1595 SAA5050 895p 5070 1895 8T26 119p 8728 1 19 8795 99 8797 99 811595 227p 811596 811597 811598 6522 6522 6532 Posibve 100mA 78 O5A 38L12A 78L15A 78124A 1 Amp 70202 78051 45 78127 45 78157 45 78241 45 Negative 100mA 092 79 05 79112 79115 3 T0220 79051 7912T 79157 79241 TRANS ISTORS 2N2219 2N2219A 2N2220 2N2221A 2N2222 2 2222 2N2223 2N2223A 2N2368 2 2369 2 2369 2N2904A 2N2905 2N2905A 2 2906 2N2907 2N2907A 2N2926 2N3053 2N3054 2N3055 2N3055H 2N3439 2N3440 2N3441 2N3442 2N3638 2N3702 2N3703 2N3704 2N3705 2N3706 2N3707 2N3708 2N3708 2N3710 2N3711 2N3773 2N3819 2 3902 2N3903 2N3904 2N3905 2N3906 2N4030 2N4031 2N4032 2N4036 2N4037 2N4400 2N4401 2N
165. 4402 2N4902 2N4903 2N4905 2N4906 2N4907 2N4908 2N4909 2N5089 2N5190 2N5191 2N5193 2 5194 2 5245 2N5246 2N5247 2N5248 2N5249 2N5266 2N5401 2N5415 2N5416 2N5447 2N5448 2N5449 2N5450 245451 2N545 2N5458 2N5459 2N5460 2N5551 2N6121 2N6122 2N6123 2N6124 2N6125 2N6126 2 6129 2 6130 2N6131 2N6132 2N6133 246134 2N6253 2N6254 25 1306 3N201 40361 40362 BC109C 140 147 8 147 1478 BC147C BCi48 BC148A BC1488 8 148 BC149 BC1498 149 8 157 8 157 BC157B 8 158 1588 BC159 BC159A BC159B BC159C BC160 BC161 BC167 8 169 169 169 17 177 8C1778 8 178 BC178A BC1788 8c179 8C1798 6C179C BC182 182 BC1828 BC182L BC1821A BC182LB BC 83 8C183A BC183LC 8 184 8 1848 8C184C BC186 BC187 BC212 212 6C2128 BC213 BC213A 2138 213 BC213L BC213LA BC213LB BC213L C 214 BC2148 BC214C BC214L BC2 4LB BC214LC BC300 BC301 BC302 BC303 BC327 BC327A BC327B BC327C 8C440 441 460 BC461 547 BC550C 560 BCY 70 8 71 72 BD124 BD131 80132 80135 80136 80137 80138 80139 80140 BD239A BD239C BD240A BD240C BD241A BD241C BD242A 80242C BD243A BD243C 80244 BO244C 80245 80245 BD246A BD246C BD249A BD249C 250 BO250C 80579 80530 80535 80536 80537 80538 80539 BD539C 80540 BD540C BDX668 8DX678 BDY54 80 55 BDYS6
166. 49 2230 8 25 20 0322 8 25 2040 8 95 THORN 3000 1 M 5n GRUNDIG 1500 15 45 THORN 8500 580 POTENTIOMETERS 20MM QUICK BLOW FUSES IT eveao 255 5 012 200 5p each PHILIPS G8 8 50 PHILIPS G9 899 REPLACEMENT MIN HORIZONTAL POTS 012 20MM ANTI SURGE FUSES Buon 13 39 ELECTROLYTIC CAPACITORS CONVERGENCEPRE SETS 0 30 TD cm PYE 725 10 95 SLIDERS LOG 0 48 100 800 15p each RBM T20A 12 40 DECCA 30 400 400 350V 2 85 SLIDERS LINEAR 0 48 1 12 TANDHENGE S0 1115 DEEN 80 100 400 350 2 99 EFUNKEN711A 19 15 1700 THORN 1590 9 50 200 200 400 350V 3 55 SPARES amp AIDS THORN 8000 9 20 GEC 2110 600 300V 2 25 FOAM CLEANSER 0 79 PUSH PULL MAINS SWITCH THORN 9000 9 95 ITT CVC20 200 400V 1 80 FREEZE IT 0 82 PHILIPS G8 600 300 2 25 SOLDA MOP 0 64 ETC 1 02 THORN MAIR TRANSFORMER PHILIPS G9 2200 63V 118 SWITCH CLEANER 0 79 PYEIF GAINMODULE 6 99 2 35 PHILIPS G11 470 250V WWW americanracdiohistorv com WD40 4 25 ANODE 27kV 0 69 ELECTRONICS amp WIRELESS WORLD JULY 1984 TELEX 0474 813225 SELECTRON HOUSE WROTHAM ROAD 966371 3LINES GREEN MEOPHAM KENT DAI30QY COMP COMPONENTS LTD
167. 49 813 125 86 8417 6 00 14 19 ECL83 3 00 281 1 50 152 131 25 QF451 82 50 037 12 00 3824 11 00 6BL7GT 4 50 766 150 833A 193 16 18042 11 53 13 73 ECLS4 1 50 EZ90 200 152 25 QQV02 6 30 50 UABC80 1 25 3B28 15 35 6BM6 115 00 7H7 4 00 866A 20 03 18045 10 49 ESICC 800 ECL8S 1 50 FW4500 3 50 MX163 20 25 00 03 1020 50 UAF42 2 50 3829 20 05 6BN6 2 00 7R7 425 872A 200 1327 ECL amp 6 1 75 FW4800 3 50 MX164 25 52 QQVO03 20A UB4I 300 3B240M 1750 6BQ7A 3 50 757 3 50 922 6 00 Tested 810 EF37A 5 00 35 00 166 147 00 18 2 25 3B241M 1750 6BR7 6 00 774 225 931A 18 50 Ex Equipment E83CC 8 40 EF39 2 75 551 12 00 MX168 50 00 QQV06 40A UBF89 1 50 3023 25 00 6BR8A 3 50 724 2 00 1624 4 00 43CX250B 6 50 E86C 8 5 EF40 5 0 GI80 M 17 50 N78 15 00 65 UCC84 1 75 3C45 24 50 6857 6 00 11E3 55 00 1625 3 50 CV Devices E88C 8 25 EF4l 3 50 624020 12 00 3 25 QQV07 50 68 60 0 85 1 85 10045 6BW6 6 00 12AH8 5 00 2050 7 50 Large stocks E88 8 42 42 450 G4001K 17 50 OA3 2 55 QQZ06 40A UCF80 2 00 47 00 5BW7 LS0 12 76 15 42126 Priceson E90CC 9 47 50 2 50 GN4 9 00 4 6 00 62 20 UCH42 250 3 29 45 00 6BX7GT 5 00 12AT7 1 75 4212H 300 00 application E90F 9 90 54 5 00 GN4A 9 00 OB2 4 35 QU37 12 50 UCH81 250 354 2 00 6826 2 75 12AU6 250 5544 81 97 6 25 EFSS 3
168. 5 800 800 110 051211 150 115 0 95 60767 120 30P18 0 60 6136 2 50 240 EESO 250 GTRISOW 100 900 125 05112 320 115 075 654A 150 3019 190 6 750 5 6020 35 00 84 0 40 1213 5 00 F80 0 80 2 50 7 1 10 30PL1 6157 2 50 E82CC 3 50 den Ta Gxu1 1350 PCC85 0 54 051215 2 10 bees 250 2K25 Raytheon 150 6SA7GT 100 30PL13 0 60 6201 6 45 250414255 120 GXU3 2400 PCCBB 070 051218 5 00 3 50 75 00 0 95 6SC7 150 175 621 2 50 109 GXU50SS PCC89 0 70 0037 950 484 085 2K26 95 00 450 6567 120 31uS6A 550 6267 1 50 E86C 9 50 EFBD 055 14 50 PCC189 070 0 03 12 4 95 05 3 50 3A 107B 12 00 3 50 65 7 1 20 33A 158M 6350 2 00 DO Faas 350 GYSO 120 0 70 QV0525 175 UU7 8 00 3A 108A 9 00 100 6SJ7GT 1 20 19 50 6360 450 E88CC 300 950 GY802 1 00 06 0 80 0 06 20 29 50 008 9 00 1098 11 00 150 65 7 0 80 35A5 4 50 6386 14 50 ECC 79 EF86 125 6230 1 00 2 0 80 0 08 100 UYA 3 50 3A 110B 12 00 100 6SK7GT 1 20 35L6GT 200 6545 8 50 E90F 7 95 EF86 Special 6231 100 0 65 145 00 UY85 0 70 141 1150 0 72 661767 0 85 35 4 0 70 6550A 800 450 uai 250 6232 1 00 PCF82 0 60 Qv2 250045 00 2 3A 17J 7 50 160 6SN7GT 095 3523 185 6870 11 50 Ho 6 33 eres d 0 85 G233 4 50 PCF84 0 65 QY3 125 49 50 250 00 3A 167M 10 00 3 00 6507 0 80 7 4
169. 5 0 u 615 0 5 0 1 9 0 Lb Lb 82 0 755982 111 61515215455 5 2 011 687 812595071 125095191 1 0589 0 1 0 2 09 081 81056555691 222065001 09252957291 902595671 1758501 581 85 061 24150655061 5 081 265871 0 599 891 0925095491 1815665291 Ge 569559 0 295591 82151558601 852599 281 61 19891 62 69 69 69 569 9 1 511245189 92 9 0 1 51 799027 499009 D 499052 9 x9 499055 9 06 9 672 999 x Ajroedes 9115 ve ae tT BI 81 Veto AZTI 49 AB 1 YEL ADCT VC C AgifT WEDS 0 AB fT NT AB fT YAD ST VC CD ABT 49008501 YOLO APET 99 560 91 gt YB ODEO O AB WS 9 gt AGLI vo t OAT LIT VP DP NI ABST YSO ABOT 980620208 VL0 ASTD 49051502 4900552 ACT 98005202409 NI 1 spaau Janog MZ AZ MZ AZ MC MC XH MC MC 0 0 LEL 0 0 0 100 gpz T arie 0 8921 o 1 are 0 8 02 41490 8 21 111 0 8 21 16720 8P0Z wie 0 APZI ANAT 0 8902 1190 8902 8 1429 gt 8902 gt 8921 2 0 8921 916720 89
170. 50 sample 1 25200 134 36 38 40 2 4 39 SMHz vision carrier 34 75 MHz sound 40 75 2 vision fo suit synth U321 tuner Mullard i f bandpass Phase shift set esizer To remove channel offsets pulling 50kHz max 40 75MHz vision low phase carrier shift MHz Limiter centred on vision carrier allows noise through 6MHz trap Group delay equalizer operating between 4 5 amp 5 5MHz Back porch Balanced 50 a input if used View on leads Fig 96 Amplitude and group delay performance of s a w filter recently introduced by Signal Technology 648 Sound carrier 34 75MHz 6MHz true intercarrier 6MHz Det intercarrier Gated a g c black level sampled Wideband a g c peak det ELECTRONICS amp WIRELESS WORLD JULY 1984 Balanced 50n output e g when using TDA 541 Fig 97 Block diagram of the BBC designed u h f tv receiver RC1 511 giving outputs of 1 volt composite video and good quality sound 4048 gain a g c with long tailed D p Carrier i f Headphone E output d Low 2 line balanced output N gt Active filters optimized for aircraft flutter or aerial signa flutter due to movement of narrow beam high gain aerials WWW americanradiohistorv com 39 Readers of this series puzzled the numbering of component references on page 33 of the May installment may be reassured
171. 500 6BW7 150 10P14 250 15064 245 2900 1190 EAF42 120 Ekgo 072 700 000 250 12503350 xc24 150 4832 1950 6BWB 400 10218 078 15506 25 00 Q 3042 2400 EAFB0 350 p ogs 350 5 300 rse 4500 XC25 _ 050 4BO7A 175 6BX6 oae 100011 100 185BT 150 3283 2400 150 EL 095 KIC 350 PENASDD 3 00 Reese sags Seo dci GBXOGT 350 100019 1506 AC HL DD4 00 3 95 5 225 4 400 PENAS 2 00 425 5215 XFWSO 150 4C28 25 00 6826 250 ME2 1650 307 5 00 4 00 0 60 EY Philips 400 2520 935 567 595 xG2 6400 4CX250BLI T 6B27 295 5500 328A 1500 ACT22 59 75 EBC33 2 50 400 5421 2 50 56233 2895 35 00 37 50 604 110 12AD6 150 388A 17 50 1200 EBCA 195 Etse Teo 200 PL36 095 S11E12 38 00 5 500 2250 4CX2508 665 195 12468 150 42545 800 52 8 50 150 EL KT66 OSRAM 150 S30 2k 12 00 XLI 5V 150 49 00 6C6 250 1245 100 4910 200 AH221 3900 EBCS0 09 E32 2200 1050 5181 072 Sio4 IK 10 00 628 750 4CX2508 66866 150 124 6 095 5728 3500 238 39 00 EBC9 090 350 6 90 072 5109 1 1500 XNP12 250 surplusex 6 11 250 12477 115 705A 800 AL60 600 250 t 200 1495 50829 060 S130 595 10
172. 602916 Preamplifiers linear amplifiers and r f components Mutek Ltd Bradworthy Holsworthy Devon EX22 7TU Tel 040924543 Preamplifiers etc Thanet Electronics Ltd 143 Reculver Road Beltinge Herne Bay Kent CT6 6PD Tel 02273 63859 63850 Icom South Midlands Communications Rumbridge Street Totton Southampton SO4 4DP Tel 0703 867333 Yaesu KDK Waters and Stanton Electronics 18 20 Main Road Hockley Essex Tel 0702 206835 204965 FDK Trio Wood and Douglas Ltd Unit 13 Youngs Industrial Estate Aldermaston Reading RG7 4PQ Tel 0736 5324 2m transceiver modules WPO Communications 20 Farnham Hassocks West Sussex BN6 8NS Transceiver kits 78 PREFERRED VALUES It is not unusual for the engineer to be condemned for incompetence when his strictly practical camel fails to look like the mathematician s image of an elegant but non existent breed of horse Preferred values are selected not by ngid arithmetic but as the result of some very clear and simple thinking about tolerances and their application to the real world Since the 20 range has produced the most glaring anomaly let us use it as our example To produce a series of figures such that any value will fall into the tolerance band of one of them they must be related so that the top end of the lower band coincides with the lower end of the higher one In our case this is to say that 120 of the lower should be 80 of th
173. 61 120LC 75 00 TDA1010 215 1365 3 95 CV429 89 00 F31 13LG 65 00 M61 120W 75 00 TDA1038 250 UPC2002H 1 95 1450 35 00 41 1231 160 00 56 45 00 TDA1037 135 555 0 35 CV1526 19 00 F4 141LG 160 00 5 4 0 7 45 00 MA TG 2195 ee 2185 15 00 F41 142LC 185 00 SE42BP31AL 55 00 215 256 HM 2191 19 00 M7 120W 19 00 SE42BP31 55 00 TDA12700 3 95 741 0 35 CV2193 15 00 M14 100GM 45 00 SE52AP31AL 55 00 1DA1327 170 74 050 CV2328 65 00 14 100 55 00 SESFP31 55 00 TDA2002 195 bu 0 35 5119 85 00 M14 100LC 45 00 1937 65 00 1042025 5585 D 9 4 5320 85 00 M17 151GVR 175 00 T948N 65 00 6180 1805 0 65 389 55 00 M17 151GR 175 00 T94BH 65 00 TDA2822 198 785 065 08 110GH 3900 4500 55 00 TDA2523 2 95 DACH 45 M19 19168 36 00 V4252B 65 00 D10 210GH68B 65 00 M19 103W 55 00 V4274GH 65 00 BERAO 023 D10 210GH72 65 00 M23 110GH 55 00 V4283W 65 00 Edid 02s 043 D10 230GH 35 00 M23 Y1W 55 00 V5002LD 65 00 BERG 30 TIPA1C 0 42 D10 230GM 35 00 M23 111GH 55 00 V5004GR 59 00 BERSO 920 2 042 D10 293GY 90 55 00 23 11110 55 00 V5004LD 59 00 TIP338 075 D13 27GH 49 50 M23 112GM 55 00 V6001GH 65 00 BFR91 175 Teese oie D13 30GH 49 50 M23 112GV 55 00 V6006GH 65 00 BETA 926 045 D13 33GM 49 00 M23 112GW 55 00 V60070P31 59 00 008 pac 045 D13 47GH 26 55 00 M23 112 55 00 V6007GW 65 00 TIPA2C 0 47 D13 47GH 34 55 00 M23 112LD 55 00 V6008GW
174. 65 Access or Barclaycard Visa Tel 01 684 1665 for SAME DAY DESPATCH Cash prices include CIRCLE 44 FOR FURTHER DETAILS BAMBER ELECTRONICS Marconi Modulation Meter Type TF2301A Marconi RMS AC DC Voltmeter Type TF 2607 Marconi RF Power Meter Type 0A 7024 4 Marconi UHF Attenuator Type TF 2168 Wavetek LF Generator Type Solartron DVM Type 1420 2 Hewlett Packard Power Supply 0 40 amp 30amp Type 62688 SchomandiModulator Type MAF BN 841962 Schoolmandi Synthesizer Type NO 100M Rohde amp Schwarz Decade Signal Generator 0 3 500 Mhz Type MDV BN 41104 Rohde amp Schwarz Sweep Signal Generator 50Khz 12Mhz BN4242 2 Rhode amp Schwarz Frequency Indicator Type BN47051 Rhode amp Schwarz Group Delay Measuring Equipmentindicator Marconi AM Signal Generator 10 500Mhz Type Pye Base Station Type F30 AM High Band amp Low Band from Pye Base Station TypeF401 AM High Band Pye Base Stalion TypeF17 FM High Band Pye Reporter Type MFG AM High Band amp Low Band PyeEuropa Type MF5 FM High Band Pye Europa Type MF5U UHF Pye Olympic Type M201 AM High Band Pye Motofone MF5 AM High Band amp Low Band Pye Westminster Type W30 Low Band Pye Bantam Battery Chargers Rank Telecoms Battery Charges Pye pocketphone PFI Battery Chargers 12 Way ITT Starphone Battery Chargers Type Tektronix Hard Copy Unit Type 4601 75 Advance Pulse Generator Type PG 5002 50 Siemens Milliwatimeter5Oohm 500mW 0 12 4Ghz 50
175. 6p BUX80 600p 147 120p 234037 5 1 5401 2 12 12 400 85 74 5191 130p 74252 8505 28540 250p 563524 300p 338 16 69 350p TIP2955 90 2 4123 4 27 1 5403 4 14 12A500V 105p 7405192 130 345283 OPTO ELECTRONICS 461 40 E310 50 TIPS055 70 2 4125 6 27 1 5404 5 14 16A400V 110p 7415193 1 0 745283 300 58 477 8 36p MJ413 250 11593 30 2N4401 3 25 1 5404 7 19 16A500V 130p 744 5194 130p 42288 1800 1509 2N5777 TIL32 55 516 7 50 MJ802 400p VNIOKM 50 2N4427 120p 15920 128000 130p 74 5195 130 745289 2255 77 1178 55 5478 20 2501 225p VN66AF 90 2N487 50 BRIDGE TIC206D 7451965 130p 2 en 9000 ORP12 120p TIL31A 120p BC548C 12 MJ2955 90 100p 2N5087 30 TIC226D 75 748197 1308 45373 4005 3000 ORP6O 7181 120 Hepes 16 2256 270108 245089 7 2 lt 60 120p TIL100 75 18 17 7 7 8240 250 745374 400p 300 p BC559C 24 27 462 45 2 5191 805 1 50V 19 7415241 250 742450 PEG OPTO ISOLA BCY70 30p MJE2955 150p ZTX500 20 2N5245 40 1A 00V 20 THYRISTORS 7415242 140 748571 300p ene 074 130p TIL111 BCY71 36p MJE3055 120p ZTX502 20 2N540 1A 400V 25 34400V 46
176. 704 5 16 OA47 10 28 90 74153 74 5164 140p 748109 sop OTHER 169 16 BRY39 45 55 2N3706 7 16 OA90 91 120 74154 165 1609 345200 450 Op 172 18 BSX19 20 30 TIP42A 243208 16 OARS 9p 12122 74LS166A 250p 745200 450p 100 177 8 30 BU104 225p 2 5 2N3773 200p 200 TRIACS ces MODA Ie er Im ines we 74157 p LM317K T03 250p78H12 850p 4 N914 4p 7415170 220p 745240 280p 0 150 78HGKC 600 184 16 30109 225p TIP120 75 2N3866 120p 1 916 74160 74 6173 120 74244 4005 LM337T 225p 78HOSKC 650p 187 30 BUI26 150p 21 75 2N3902 700p 1N4148 4 3A400V 7416 7405174 120 74225 00 2208 LM323K 5450 78GUIC 225p 212 3 16 BU180A 120 TIP122 80 2 3904 22 1 4001 2 5 400 70 74162 7405175 120 745207 2005 LM3501 350p79GUIC 250 BC214 18 80205 200p TIP125 75 2N3905 22 1N4003 4 6 500 88 7405181 250 745298 3005 P M723N 50 79 700 BC237 16 80208 200p 126 80 233906 24 1 4005 400 75 74 5183 270 746260 100 300 TL494 300p ICL 7660 250 327 16 BU406 145p 142 120p 2 4036 65 1 4006 7 7 500 95 7405190 130 745260 100 90 11497 300p LM305AH 250p 337 1
177. 73 Multimeter offers analogue bar graph offering a combination of digital with digital display and the POSTS display with analogue br graph joe RUNI 65 oilers us compatibility trend indication uke JF75 Autoranging for easier operation dB measurements on AC and DC volts 16 reference resistances between 500 to Relative measurements with selectable references Display warnings for confidence and safety 285 PM2519 51 DMM with IEEE interface 495 Single switch selects measurement OC accuracy 0 5 functions All measure volts amps auto manual ranging ohms and diode test 3200 count and high speed autoranging Self diagnosis and automatic battery power down Flu R es and 8 e i ied OC accuracy 0 3 touch hold 95 facility multi purpose holster ADD 15 VAT TO ALL PRICES Carriage and Pack ing extra Electronic Brokers Ltd 61 65 Kings Cross Road 1 London WC1X SLN Tel 01 833 1166 Telex 298694 CIRCLE 61 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com NEWS Computer crashes No less than three different computer companies ceased trading in one week Dragon Data Tycom and Camputers The chief executive of Tycom is Sir John Clark Conservative Members of the European Parliament His major customer has been the Conservative party who have installed the Microframe computer in a large number of constituency o
178. 73 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 Press International Quadrant House The Quadrant Sutton Surrey SM25AS Business Press International 1984 Wireless World be obtained abroad from the foliowing AUSTRALIA and NEW ZEALAND Gordon amp Gotch Ltd INDIA Wheeler amp CANADA The Wm Dawson Subscription Service Ltd Gordon amp Gotch Ltd SOUTH AFRICA Central News Agency Ltd William Dawson amp Sons 5 Ltd UNITED STATES Eastern News Distribution Inc Floor 111 Eighth Avenue New York N Y 10011 104 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com If you need assistance in HiFi audio service us tg Here s all the help you need Philips versatile PM5109 LF generator and unique combined distortion meter oscillator the PM 63089 give you all the help you need for HiFi and audio service applications They re easy to operate and economically priced PM 5109 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 1
179. 732 5807 7408 0 20 7438 0 32 7482 075 7419 1 54 74154 1 80 74195 1 0 920 2 90 Nuvistor base 209 3 Pl soe DG736 6500 application 7409 0 20 7440 0 32 7483 1 00 74120 0 83 74155 0 90 74196 1 35 TBA920Q 2 90 Spin DIL Teras 0 10 3IP2 80 DH39 56 83 7410 0 17 7441 090 7484 1 05 74121 0 43 74156 0 90 4197 1 35 9900 2 90 Kpa p reta A0 esi 9 113 12 7412 029 7442 072 7486 039 7412 0 62 74157 0 75 74198 170 TCA270Q 2 90 14 Tamela 3177 10 00 12 00 7413 032 7447AN 117 7490 0 60 74123 148 74159 2 20 74199 2 30 760 1 38 ce ARP 3500 1200 7416 0 32 7450 0 18 7491 0 82 74125 0 58 74170 2 40 570 2 30 Valve Sereening VCRI38A 12 50 7417 032 7451 018 7492 0 60 74126 0 58 74172 4 40 6305 3 50 cans all sizes 0 40 3WPl 20 00 VCRI39A 8 00 7420 018 7453 018 7493 060 74128 0 63 74173 142 TAA70 3 90 7422 0 20 7454 0 18 7494 0 82 74132 0 72 74174 1 60 TBA480Q 1 84 Terms of business CWO Postage and packing valves and semiconductors 50 per order CRTs 1 50 Prices excluding add 15 Telephone 01 677 2424 7 Price ruling at time of despatch 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 facilities available to approved companies with minimum order
180. 7460 75p 74547 140 7415643 1300 7217 300p MC3340P 200p 081 45p 6840 375 93415 600p 058880 170p 16 0 200p 7270 752 74848 140 7415644 350p ICM7555 100p 3401 Sop TLOS2 85 6009 33425 600P 1613201 450p AY523761150p 180 2006 7472 75 7556 140 MC3403 65 11085 75 P 931422 950p 100p 746922 480 18432 15 75 740551 60 7415645 350p LC7120 300 L084 100 6850 200 X210 p 746 oP 7473 7 360p 084 68850 1489 100p 923 500 19969 150 7474 100P 740595 605 7415668 120p LC7130 325 50240 900p 11094 200 6852 MC3418 960 20 0 450 7475 100 74 873 75 7415669 150p 07137 350p 50398 790p 1170 50 6524 2502 20 5 7476 80P 7405744 100p 7415670 225p 2347 50 ML920 500p 71430 120 onc MC3459 450p 480 175 7480 LF351 6221 UA1003 3 935p PROMs MC3470 6 5 740575 90 7415682 650p 6875 Sop 116 3006 7481 741515 742682 520 6353 100 042240 120 6872 ssop 14411 900p 10001200 7483A 120p 7415687 550p LF355 100 531 150p UAA170 200p 8155 745188 180p MC3486 500p COMB116 800p 74LS83A 120p TA 74 585 7485 74 586 7486 74 590 7489 7490 74 591 LF356F _ 100 190p UCN4801A 35
181. 80 BAKER AMPLIFIERS BRITISH MADE PA150 Watt MICRDPHDNE VDCAL AMPLIRER 129 4 channel mixing 8 inputs dual impedance 50 600 ohm volume treble bass Presence controls on each channel Master volume control echo send return socket Slave sockets Post 3 150 Watt MIXER AMPLIFIER 4 Inputs 99 Discotheque Vocal Public Address Speaker outlets for 4 8 or 16 ohms Four inputs 20 mv 50K ohm Individual volume controls Four channel mixing Slave output 16 x8 x5l4 Wt 141 Master volume control 240V Post 2 100 Voit Line Model 150 watt 114 MONO SLAVE 150 watt 80 Baker Stereo Slave 150 150 watt 300 watt Mono 125 Post 4 _ 30 Console decks pre amp 105 Carr 6 BAKER MOBILE PA AMPLIFIER All transistor 60 watt RMS 12v DC amp 240v AC 4 inputs 50k Aux 2 mics phono Output 4 8 16 ohm 100 volt line 89 Post 2 WATERPROOF HORNS 8 ohms 25 watt 10in 20 30 watt 8 23 40 watt 121 29 20 watts 12in plus 100 volt line 38 Post 2 BAKER PORTABLE DISCO 150 watt Twin console amplifier mike and headphones twin speakers 330 300 watt 399 Carr PA CABINET SPEAKERS Complete ohm 60 watt 17x 15x9in 27 Post 4 4 or 8 or 16 ohm 75 watt 23x 15x lin 52 90 watt 32x 15x 71 150 watt 80 Carr 10 Black covered BAKER LOUDSPEAKERS Post 2 each MODEL INCHES OHMS WATTS TYPE PRICE DISCO GRO
182. 80 64646 Telex 32250 Z2 thandar ELECTRONICS LIMITED 1 CIRCLE 21 FOR FURTHER DETAILS NEW from Kontakt The capability and effect of compressed air in a handy can TENSION 67 efficiently removes dust and deposits from electronic components electronic and electrical appara tus microscopes medical equipment cabinets etc Abso lutely no spray residues No compressed airline needed With plug in nozzle even blows mmm around corners Ready for use in the service kit Kontakt 60 Dissolves oxides and sulphides re moves dirt oil 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 cellent lubricant for all electrical and electro mechanical systems Solve all your Power Problems by contacting Spray Wash WL 5 KON pue id cleaner for reliable washing and E degreasing of electrical equipment and iali i imi 4 components For removal of dirt grease E M S specialise in systems to eliminate your ula Lisa power problems ties Products range from 35VA switched square wave ALSO AVAILABLE Power Packs to 1KVA fully uninterruptible sine wave syste ms A COMPLETE RANGE OF INDUSTRIAL AEROSOL SPRAYS SK10 Soldering Lacquer K75 Cold Spray K70 Plastic Spray K88 Oil Spray K701 E M S a
183. 984 R66 To collector 2k2 of To IC pint 01 00 09 00h with Bell 103 tones TBBS Southampton 0703 437200 17 00 08 00h weekdays all day at weekends North Birmingham BBS 0827 288810 24 hours Blandford Board 0258 54494 24 hours Stoke ITEC BB 0728 265078 24 hours Southern Bulletin Board 0243 511077 24 hours BASUG British Apple Systems User Group board 0742 667983 24 ours The following commercial sys tems operated by electronic component suppliers make no charge to users except where shown Distel Display Electronics Ltd Lon don SE19 01 679 1888 V 21 A 1200 75 baud service is to be added test port on 01 679 6183 Estelle STC Electronic Services Harlow Essex 0279 443511 V 21 0279 442288 V 23 busi ness hours Rewtel Cirkit formerly Ambit International Brentwood Essex 0277 232628 Some facilities are available only to subscribers Maptel Maplin Electronics Ltd Southend on Sea 0702 552941 WWW americanradiohistorv com Fig 2 Space for this power supply is provided on the p c b Viewdata Prestel Microcomputing details from Micronet 800 Scriptor Court 155 Farringdon Road London 3AD Enquiries 01 278 3143 The quarterly subscription of 13 for domestic users gives access to Mic ronet 800 Viewfax 258 and all sec tions of Prestel not restricted to other closed user groups Prestel for information ask the oper
184. 991 There is no difficulty in princi ple in substituting optical fibres for copper cables in the majority of data transmission ations After multiplexing the data in the normal manner the electronic modulator drives a light emitting or laser diode rather than a coaxial line ampli fier Fig 1 At the receiving end the signal can be treated again in the conventional manner once it is beyond the detector preampli fier In small systems the addi tional complexity is minimal whilst complex data systems such as telephone trunk routes can actually be simplified by adopting optical fibres as the transmission medium The range of telecommunic ations applications for fibre optics can be conveniently divided into three areas public telephone network broadband entertainment and information services computer local area networks Public telephone network Because of the very low band width required for each telephone handset it is doubtful if there will ever be an economic need to replace the usual copper wire pairs with an optical fibre This position changes of course when considering an integrated data network including telephony television and data link The major fibre application is in the area of junction and trunk tele phone transmission where the traffic has been concentrated and multiplexed to a much higher data rate Here experience has shown that the first generation systems have fallen
185. AL IMAGE ANALYSIS by S Levialdi PRICE 26 00 SEMI CUSTOM IC DESIGN amp VLSI by PJ Hicks PRICE 13 50 INTRODUCTION TO MOSLSI DESIGN by J Mavor PRICE 18 50 HANDBOOK OF BATTERIES amp FUEL CELLS by D Linden PRICE 63 00 THE DESIGN amp DRAFTING OF PRINTED CIRCUITS by D Lindsey PRICE 41 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 ENCAPSULATING EQUIPMENT FOR coils transformers components degassing silicone rubber resin epoxy Lost wax casting for brass bronze silver etc Impregnating coils transfot 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 MORSE READING PROGS Work on clean sig nals without hardware interface ZX81 1K UNEX PANDED MEMORY Translated code with word and line spaces for easy reading Automatic scroll action 7 incl SPECTRUM 16 48 Scroll action with 10 page scrolling memory instantly accessible page by page 8 incl All types variable speeds Feed signal direct into EAR socket Pinehurst Data Studios 69 Pinehurst Park West Moors WIM BORNE Dorset BH22 OBP 2532 PRINTER FOR BBC MICRO or any computer with RS23
186. Burford Road London 15 25 01 555 0228 3 lines 6 CIRCLE 59 FOR FURTHER DETAILS DEC WRITER 11 LA36 Very Good Condition 225 GE TERMINET 300 with keyboard 125 Upper Lower Case TRANSTEL DOT MATRIX PRINTER Compact Interface 230V With info 55 ea TELETYPE 33 DATA DYNAMIC 390 Printer board Punch amp Reader 85232 75 9 MONITDR Cased Non standard with info 20 12 MONITOR Cased Non standard with info 15 ea AZTEC 20 Black and white MONITOR Video 450 TV Style 20 MONITOR Black and white Video In 230 JUSTIN POLARAD SPECTRUM ANALYSER 10 2 2000 TELEQUIPMENT CT71 CURVE TRACER 400 OSCILLOSCDPES TEK 434 STORAGE Dual trace 25MHZ 850 TEK 453 Dual Trace SOMHZ Delay Sweep 375 COSSOR 4000 Dual Trace 50MHZ Delay Sweep 250 COSSOR CDU150 Dual Trace 35MHZ Delay Sweep 200 ADVANCE 0525 Dual Trace 5MHZ 70 POWER AMPLIFIER 230B 10 500MHZ 400 AIRMEC FM AM MOD METER type 409 3 1200MHZ 375 BONTOON FM AM SIG GEN 202H 54 216MHZ 250 R amp S MICROWAVE POWER METER NRD BN2412 0 3 2GHZ 250 UHF SIG GEN 612A 450 1230MHZ 200 ADVANCE AUDIO SIG GEN J3B 10HZ 100KHZ 175 MARCONI IN SITU UNIVERSAL BRIDGE TF2701 300 Item No OSCILLOSCOPES 406 TEK465Dual Trace 100MHz Delay Sweep 950 407 SRUCD ADVANGE 0533008 Dual Trace 50MHz Dual Time Bas 400 408 TELEQUIPMENT D83 Dua Trace 50MHz
187. C Post 2 FAMOUS LOUDSPEAKERS M i i MAKE MODEL SIZE WATTS OHMS PRICE POST Drive Cartridge Price AUDAX WOOFER Sin 25 8 05 f BSR P170 Rim Ceramic 22 GARRARD 6200 24 SDODMANS HIFAX BSR P207 Rim Cerimit n GOODMANS HBWOOFER Bin amp 350 1 BSR P232 Belt Maareh 2 WHARFEDALE WOOFER Sin 3 BSR P200 Belt CELESTION DISCO GROUP 10n 50 8 16 21 2 aan a GOODMANS HPG GROUP 12in 120 8 15 2950 2 858 12044 P267 Belt Ceramic 24 GOODMANS HPD DISCO 12in 120 815 2950 2 2 GOODMANS HP BASS 15 250 8 72 f4 BSR Budget Rim a GOODMANS 5 18 230 8 34 4 PSR m Magnetic 25 RCS STEREO PRE AMP KIT To build Inputs for GARRARD 62 Rim Ceramic 22 high medium or low imp volume control 3 50 THE INSTANT BULK TAPE ERASER 11 50 Post 95p and PC Board Can be ganged for multi channel Post 65p Suitable for cassettes and all sizes of tape reels AC mains MAINS TRANSFORMERS Post Wil also demagnetise small tools Tape Head Demagnetiser 5 2500 250V BOMA 634 BA EIV Ee 0 mA 6 4 ALUMINIUM CHASSIS 2 4in deep 6x4 175 8x6 220 10x7 220V 25 lamp 3 00 220V 45ma 6V 2 Amp 4 00 1 275 12x8 320 14x9 3 60 16x6 3 16x 10 3 80 12x3 220 250V 60mA 6V 2A 5 00 1 14x3 2 50 13x9 2 80 ALUMINIUM PANELS 6x4 55 8x6 90 14x3 90 10x7 1 15 S
188. C OC 20 Meg ohm A 29 13 3000 30 rangs 10A 00 20 Meg ohm 33 00 6010 28 ranne 10 AC 0C 20 Meg ohm 33 00 KDS5C 28 range 10A AC OC 20 Meg ohm A 34 74 KD615 18 range 10 OC 2 Mag ohm plus Hie tester 34 74 7030 As 6010 but 0 1 basic 41 30 DM3350 Autorange plus cont tester 18 range 10A AC OC 2 Meg ohm DM2350 Mini autorange plus cont tester 19 range 10A AC OC 20A Max 2 Meg ohm PB 54 73 3100 Pen type auto ranging a 20 Meg ohm buzzer 39 00 LOGIC PROBES TTL OTL etc LP10 I0MH2 19 96 DLPSO50MHZ 43 44 4 either model 65 ANALOGUE MULTIMETERS Metrix ITT Professional range IUK 5 Size 110 x 45 x 185mm MX130 25 ranges 5000 ohms per volt 70C V0 1 to AC V 10V to 1000 6 0 Amps YOQUA to 30A 5 AC Amps to 30A 2 ohms 1K to 10K 55 00 MX230 29 ranges 20K Volt 100 mV to 1000 V OC 3V to 1000V AC 50 to 10A OC 3uA to 10A 59 00 1K to 10 Meg ohm MX430 32 ranges 40K Volt DC 4K V AC to 1500V 0 5V to 1500V 254 to 15A QC to 15 AC 50 ohm and 500 ohm scale K ohm and 20 Meg ohm 89 HIGH VOLTAGE METERS Olrect meter reading 1 80 0 40 22 00 KHP3ON 0 30 0 45KV 34 74 UK elther model 1 00 AC CLAMPMETER 0 300A 0 600V AC D 1K ohm Total 9 ranges with carry case and leads 57300 26 04 UK 65
189. C808 3 00 8204 7 5 2C39A 1 65 7 i 1 21515 12 50 1 55 81 2 50 M8212 1137 21519 6 00 6 5000 2643 70 00 687 3 25 6SN7GT 3 00 15083 835 7551 6 25 DLSI6 12 50 1 50 250 M8223 600 PL801 1 50 oo 2021 3 25 688 3 25 6507 349 150C2 3 25 7586 12 00 DLSI9 12 50 6 2 50 9 24 M8224 620 PL802 6 00 TY7 6000A 2E26 8 15 6BA6 150 6567 400 15004 6 00 7587 18 50 DM70 200 5 3 00 EY86 1 75 8225 4 50 PY33 2 50 485 2142 98 00 6BA7 5 00 6557 275 211 22 00 7609 56 00 DM71 200 42 3 50 EY88 175 M8248 14 03 PY81 1 50 TY7 6000W 2 55 175 00 6BA8A 4 00 6156 3 50 723AB 125 7868 6 00 DMI160 4 75 ECH81 3 00 5 3 00 MD2901 115 00 PY82 1 50 303 60 2 0 383 00 6BC4 4 00 6U8A 2 25 803 25 00 7895 12 00 DY87 1 50 ECH83 2 50 EY802 175 MUI4 2 50 PY83 150 TZ40 25 00 2 70B 336 00 6BE6 1 50 6V6GT 225 805 45 00 8005 110 49 DYS02 1 50 ECH84 2 50 235 175 MXII9 55 00 PY88 200 018 20 3 50 2K25 125 00 6BH6 250 6x4 200 807 3 75 8068 14 00 551 45 00 ECL80 1 50 240 250 MX123 7200 PYSOA 400 U19 13 75 34002 85 00 6816 225 6xsGT 175 18 33 8122 90 00 8 81 ECL8 175 241 2 50 MX145 5670 PY800 1 50 025 1 50 3 5007 85 00 6 4 4 50 7B7 259 812A 1833 8136 2 50 11 27 ECL82 1 50 280 1 50 151 17 25 801 150 U26 2 50 5 3 00 6BL6 85 00 765
190. CE IN THE ELECTRONICS INDUSTRY LARGE QUANTI 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 Finchley Landon 12 5 mins from Tally Ho corner Telephone 445 2713 0743 CIRCLE 29 FOR FURTHER DETAILS 68 HENRY COMPUTER SHOP OPEN 6 DAYS A WEEK ORDER BY POST OR PHONE CALLIN AND SEE FOR YOURSELF 80 BUS MULTI BOARDS BUILD A CUSTOM SYSTEM FROM SCRATCH or expand your GALAXY or NASCOM Demonstrations for callers GM811 CPU 125 00 6M832 SVC 195 00 6MB29 0 5 51 145 00 GM813 CPU 64K RAM 225 00 EVB14 IEEE 4BB CONTROLLER 140 00 GM802 64K OYNAMIC RAM 125 00 GMB27 87 KEY KEYBOARO 85 00 GMB39 PROTOTYPING 12 50 MP826 STATIC 185 00 GMB16 MULTI I 0 125 00 IO 828A SUPER PLUTO COLOUR GRAPHICS PROCESSOR 192K RAM 499 00 GM833 RAM DISK 512K 450 00 UK 8 export extra at cost ALSO IN STOCK MOTHER BOAROS FRAMES CABLES POWER SUPPLIES KEYBOAROS SOFTWARE etc FULL LEAFLETS OETAILS OF SUITABLE PERMUTATIONS SENO LARGE SAE We can advise also with terminals and complete Galaxy computers with monitors and Oisks ready to use NASCOM 2 Avaliable in both kit and bullt form Featuring Microsoft Basic NAS SYS monitor full QWERTY keyboard of the highest quality 4MHz 2804 processor full AS232 1 0 and parallel 1 0 One of t
191. CTRONICS LTD 40 CRICKLEWOOD BROADWAY LONDON NW2 3ET 01 452 0161 01 450 0995 TIx 914977 30 RESISTORS CARBON FILM 5 HI STAB 1OW NOISE 10070 1 4 E24 2p 1 2 E24 3o 12 6 2WE12 20 METAL FILM ULTRA STABLE 0 4W EXTRA LOW NOISE 106 TO 1 E24 6p LOW OHMIC GLAZE 1 2W 02211108 211 E24 Mp WIRE WOUND ON CERAMIC E12 SERIES 2103W 0 2212 to 33011 28 7W 0 4701 to 6KB 33 to 33K 37 POTS amp PRESETS ROTARY POTS LOW NOISE 14 SPINDLES E3 SERIES to 2M LIN 38p 4K7 to 2MLOG 38p As above with OP Mains Switch above stereo 99p PRE SETS PIHER DUSTPROOF 10011 10 10M1 Vert 15 _ 15p Standard Vert 18p Standard 18 CERMET 20 TURN PRECISION PRESETS 3 4 SERIES 50u 500 89 CERAMIC 100 DISC PLATE 12 MICRO MINI TYPICALLY 5 to 10nF 7p 5 SIEMENS 7 5mm MIN BLOC E12 250V InF 10 608 7p 8n21047nF Bp 56nF 10 1508 12 100v 100nF to 150nF 13 180 to 270nF 16p 330nF to 390nF 25p 470nF to 560nF 680nF 10mm POLYESTER 250V RADIAL C280 1586 226 33nF 47nF 68nF 100nF 7p 150nF 200nF 10 330nF 470nF 13 680nF 1 SuF 2216 FEEDTHROUGH inf 500v 35p HIGH VOLTAGE Capacitors please enquire many types in stock TANT BEADS 1 22 35V 33 35 14p 47 35V 14p
192. Curve ENS DAS 9103 01 02 Logic wenn Pulse Generator Hz Tracer 1 25 Analyser 20 Column Thermal 500 Pulse Generator PESE 2701 0 7996 in TEKTRON IX TM500 2 186 steps DC 2GHz 3010A Logic Tester 8 000 BO13B Pulse Generator 2 750 284 Pulse Generator 7Ops 950 887AB AC DC Diff Voltmeter 1 950 T B2181A Digital Cassette 308 Data Analyser 2 100 8920A 312 Digit True RMS 501 Op Amp Voltmeter 695 B2901M Dual Disk Drive 4 000 381 011 PAL Test Monitor 3 750 Counter to 1 3GHz 1 000 82903A 16K MOD 95 Mo Scope 8921A 372 Digit True RMS case 82937A I F 200 25M 2 350 m v i Timer to 893A AC DC Diff Voltmeter 750 Computer 1 250 7104 Oscil oscope 1GH 6256 Steere Generator 3 8556A Spectrum Analyser Plug In Mainframe 16 500 E 931B True RMS Diff Voltmeter 1 000 300KHz 2 250 7603 Oscilloscope 100MHz 0 001 H2 1MHz 375 GOULD BRYANS 8620C Sweeper Mainframe 2 4 00 Mainframe 1 950 SUED Generator 565 25000 A4 XY T Recorder 750 86240B Sweeper Plug In 77044 Oscilloscope 200MHz 22503 Function Generator 28001 A4 with 2 x 26118 Amplifiers 2 846 2 4 200 Mainframe 2 850 1082 3M 17 E 400 ahd 26201 Timebase 1 400 B6280A Sweeper Plug In 7834 Storage Oscilloscope 400MHz 501 Pulse Generator As above but with 26202 Power Unit 12 4 18GHz 3 600 Mainframe 9 850 SHz 5OMHz 330 instead of Timebase 1 250 8640A Signal
193. E NOSE PLIERS ROUND NDSE PLIERS Price includes postage packing and VAT Offer applies to UK only Please allow 28 days for 1 delivery Registered No 151537 Reg Office Quadrant House Sutton Surrey SM2 545 83 199 ELECTRONICS amp WIRELESS WORLD JULY 1984 89 www american LANGREX SUPPLIES LTD Climax House Fallsbrook Rd Streatham London SVV16 6ED RST Tel O1 677 2424 Telex 946708 RST SEMICONDUCTORS wm BEL Su DUO IS EE on RUDD if nues 06 ZTX531 0 24 2N1893 23820 0 39 AAIIS 010 5215 1 20 BCI33 011 gpjjs 0 40 BF259 0 28 GMO0378A 175 OC20 2 50 2 50 ZTXSS0 0 25 2N2147 400 2N 1020 0 60 AAY30 0 17 5216 110 BCI77 028 BDi36 0 40 BF336 0 34 KSIOOA 045 OC22 250 200 18940 00 242148 375 2N3866 100 AAY30 0 17 5217 1 00 0 28 gpiy 0 40 0 33 MJE340 060 4 00 ORPI2 1 00 1496 0 09 232218 0 2 2N3994 0717 AAZI3 015 5220 2 30 0 28 BDI33 0 48 BF338 0 36 MJE370 0 73 3 00 R2008B 200 IN400 0 06 2N2219 032 N3905 017 AAZIS 0 15 5221 250 BC182 011 BDI39 048 400 MJE37i 0 71 OC25 1 00 R2009 2 25 1N4002 0 2N2220 020 2N3906 017 AAZI7 015 AUIB 2 50 BCIS3 01 05 BFS28 2 25 MJES20 047 OC26 1 50 R2010B 2 00
194. ECTRONICS amp WIRELESS WORLD JULY 1984 5 WWW americanradiohistorv com Two new books from Newnes SERVICING DIGITAL CIRCUITS IN TV RECEIVERS Also available DOMESTIC VIDEOCASSETTE RECORDERS A Servicing Guide R Fisher Specifically for colour television engineers this book is an in depth guide to digital circuits used in current TV receivers The early chapters deal with digital techniques and their specific applications like teletext and videotex their respective decoders being described in detail Remote control systems digital tuning and other digital circuits are also covered A glossary of terms is included which will be useful to both engineers and students Softcover 288 pages 13 95 S Beeching This book takes the subject from basics and then shows later modifications to the techniques giving examples of various manufacturers approaches to the subject Includes VHS Betamax Grundig and Philips V2000 systems Softcover 144 pages 14 95 SERVICING MONOCHROME PORTABLE TELEVISION R Wilding This dual purpose book explains the circuity of current standard miniature and combi monochrome portables together with typical faults and probable causes and contains full size reprints of British Japanese and Continental manufacturers circuit diagrams and service information BEGINNER S GUIDE TO COLOUR TELEVISION Third Edition Gordon J King revised E Trundle Colour TV has been great
195. FOR RICHARDSONS ELECTRONIC EUROPE LTD R F POWER TRANSISTORS Many other types available 2SC4588 25 45 25 460 25 4608 2804618 28 535 25 535 25 5358 25 535 25 540 28C608 25 644 25 684 25 703 25 710 25 7100 25 7150 2SCTISE 25 717 25 730 25 731 25 732 25 741 25 821 25C8288 2SC8298 25 890 25 891 2SC900 25 900 25 908 2SC911A 25 945 25 9458 25 952 25 982 25 994 25 998 25 1001 25 1011 25 1070 2SC1096L 2SC1096M 25 1 17 Backward Wave Oscillators Camera Tubes 25 1120 251121 251122 25 11628 25 1165 25 1169 25 1176 25 1177 2801178 25 12090 25 1213 25 1213 25 1239 2801241 281251 251260 25 1303 25 1306 25 1307 2501311 25 1311 25 131 25 1318 250 3688 250 3838 28C1424 25 1509 25 1546 25 1568 25 1589 25 1622 25 1623 25 1688 2501674 25 1675 25 1678 25 1729 25 1730 25 17400 25 1765 25 1815 25 1906 25 1907 25 1945 25 946 25 1946 25 1947 25 1955 2SC 966 25 1967 25 1968 25C1968A 25 1969 25 1970 25 1971 25 1972 25 1978 25 2001 25 2026 25 2053 25 2097 25 2099 25 2100 25 2103 25 2105 2802116 28C2118 25 222 25 2233 25 2237 25 228 25 2283 25 2287 25 2289 Cathode Ray Tubes Cold Cathode Tubes Diodes Display Devices Duplexers Electro Optical Devices Gas Relays Glow Modulators Ignitrons Image Intensifiers
196. GZ n n n n 5 82 5 S 5 2 5 Al 0552 1657 amp n n 8 82 15 60 02 M01 2 MSZ Mo 5 60 61 5 2 STOE X ASK S X NOT X e Janod spueq 5 x 28030 2 25 25 215 5 2 5 25 25 25 25 25 sapos aseq aseq aseq aseq 1008 1008 qos 1908 1908 1908 1008 1104 1008 1104 puey 1008 tqow puey puey 1008 1908 puey puey puey puey puey puey m WwW 058 584 fL bt bbt 88 85 55 ase ate 2 LIA 59 82 992 S IM 1 1 wal 491 bfl 89 IM Xj aths 8214 084 51 0141 3HIZZ 23I 0951 H92 14 nsaeA 3142 21 1 0062 31 worl VOOOvt MLI OT4L lt 16 1 41 nsaeA 300859 paepueis 62 21 51 05761 44 01 1 322 31 4951 VIOZWL OT4L 306214 nsaeA 30 214 nsaeA 38S paepueis OOSZ Ml 9141 XSZZ THIMW LLOZ wWa 320 91 wosy 3202 57 wo tag 00682 3 80214 5 32 31 1 34502134 nsaeA Paepueig II 3 02 57 setbnog 4 poom WZ ELECTRONICS amp WIRELESS WORLD JULY
197. Generator AM FM 7904 Oscilloscope 500 PG505 Pulse Generator 29300 A4 XY T Recorder 1 000 Mhz 2 750 5 950 1Hz 100KHz 450 Top unused mplifier wit HEWLETT PACKARD 9835A Desk Top BCD Probed50MHz pam g See 11096B RF Probe 98455 Desk 4 250 Plug In Amplifier PG508 Ise Generator 11720A Pulse Modulator 9885M 001 Disk Drive 1 750 MHz 1 600 52 SOMEHz 1 250 2 18GH 1 950 9885S 001 Disk Drive 1 200 36 Dual Trace Plug In Amplifier 86501 Ramp Generator 13328 High Resolution Display ar 250 5 8950 200MHz 1 325 10 6 400 AL 2 U tuer 830 MARCONI INSTS IEO me 7104 21908 Ss 204C Oscillator 5Hz 1 2MHz 200 2438 Counter Timer 520 MHz 795 Manframe yeta shite 2500 190 950 TEASE ede Dor 1778 ORO 7 900 volts output ainframe 26318 005 01 7 019 Dot Matris Dub TED Signal ee 450 76865 Delaying Timebase for gt BOMHz 995 35524 Trans Test Set 1 500 MHz 61 350 Manframe 1985 56503 Generator 3556A Psophmeter 850 Generator Manframe 000 250KHz 250MHz 1 250 423B Crystal Detector 0 0008Hz 100KHz 850 7DO1 DF1 Logic Analyser 56504 Generator Leveled 0 01 12 4GHz 465 2171 Synchroniser for use Plug In 2 000 Signwave 2 100 427A Analogue AC DC and with 2015 975
198. Hz 375p 7402 100p 74285 350p 74LS297 900p AD7581 15 LM386 90 SFF96364 800p 8288 11 CRT 8795 6 90p 8MHz 7403 74290 140 7415298 150p ADCOBOB 1790 LM387 120p 5 76477 600p 8755A 1800p 5278 00 Bn 7404 100 74293 140 7418299 250p AN103 200p LM389 180p 5 76489 400p 1802CE 650p 9901 E3 5 220p 74298 225p 7415921 300p POAp 74351 225p 74LS324 624 350p POAp 74365A 100p 7415348 250p 1006 74366A 100p 7415352 150p 74367A 100p 7415953 150p 100p 74368A 100p 7415356 220p 74376 200p 74LS363 180p AY1 5050 99 LM391 180p SN76495 400p 26504 412 3902 5 900p 811596 220 AY3 127C 750p LM392N SPO256AL2 6502 400p Tmigag01 355 CRT5027 811597 220p CRYSTALS AY3 1350 350p LM393 100p 800 6502A 650p 759902 350p CRT5037 418 BILS98 220 32 768 AY3 8910 400p LM394CH 350 7120 150 6800 230P 78010 TU EF9365 6 8815120 400p ed AY3 8912 500p LM709 50 7130 160 6802 300p 2 0 3596 tF9366 636 9602 220 iooKHZ 400 LM710 50 7204 150 6809 650 MC6845 650 9637AP 160P 200 2 400p CA3018A 100p LM71 70 TA7205 80 68809 12 280 3506 MC6BASSP ZN425E 8 350p 7405 7406 7407 7408 7409 7410 TA 4 CA3028A 150p LM725C
199. IC until the whole keyboard status has been read INTERFACING Music keys for the BBC microcomputer Using the computer s sound unit or external generators this economical polyphonic keyboard interface makes a musical instrument and an educational tool for storage analysis and display of music Potential of the microcomputer as a tool for teaching editing and perhaps even composing music is great as the amount of music related software currently avail able will testify This software however suffers from one serious drawback the means of enter ing musical information into the computer These means include the computer s typewriter layout keyboard and sometimes games paddles or joysticks but all are clumsy slow and error prone which is a great discouragement to the musician as opposed to the computer enthusiast attempting to use the computer creatively There systems that include the natural input device for a musician a music key board but they are mainly intended for computer based synthesizer applications Best known of these are probably the Fairlight Computer Musical Instrument costing around 20 000 and the Alpha Syntauri add on for the Apple computer costing around 2500 The Alpha Syntauri is intended for use as a synthesizer but there is now some elementary teaching soft ware available for use with it Some other mainly American music teaching systems were recently reviewed
200. IDGE 8521 645 69 WAYNE KERR VHF ADMITTANCE BRIDGE 8801 125 70 WAYNE KERA AF SIG GEN 121 10H2 120kHz 40 74 ADVANCE DUAL STAB DC PS P P 3 0 30V0 1A twice Metered 79 AVO MULTIMETER 7X 25 80 AVO MULTIMETER 8s from 45 81 AVO TRANSISTOR TESTER TT169 with leads As new P amp P 2 88 AIRMEC MODULATION METER 210 3 300MHz 90 BRANDENBURG POWER SUPPLY 374SEL 0 1000 75 91 BRANDENBURG POWER SUPPLY 2500 0 2 5 125 97 GREEN SYNTHESISED OIGITAL SIGNAL GENERATOR 161800 1 9 9 Sine Square 600 410 MARCON FM AM SIG GEN TF20028 10KHZ 88MHZ with SYNCHRONIZER 600 411 MARCDNISIG GEN 2012 400 520MHz FM 300 412 MARCONI MOD METER TF2300S 2 1000MHz iun 413 S E LABS STROBE SM8 125 414 RACAU AIRMEC SIG GEN 365A 1 320MHz AM FM 2325 375 B amp KTAPERECORDERtype7001 600 383 ove RF MILLIVOLTMETER 411A 500KHz 1GHz us 10 MARCONI DIFF DC VOLTMETER TF26060 1100V 275 390 GRFREQ METER 8 DISCRIMINATOR 1142 A 200 3916 TUNED AMPLIFIER amp NULLDETECTOR 1232 A 150 392 CLAUDE LYONS VOLTAGE STAB TS2 AC 240V 12 100 398 KINGSHILL STAB POWER SUPPLY 500 Metered 0 60V 0 0 5A P amp P 4 40 LOUD SPEAKING EXECUTIVE TELEPHONE PUSH BUTTON Many functions including 10 number memory repeat dialling etc Will connect to GPO System Brand New 25 each P amp P 4 SAMPLE OF STOCK SAE or taiephone ter LISTS Please check availability before ordering Carriage all units 7 VAT to be adde
201. II Disassembler allowing direct Angled 165p 215p 290p 440p 24 Fee Woa 1205 modification data in HEX ASCII b 2909 24 Male Male 9 50 DIN41612 dorel Continuous display of left for completion of pro IDG Pen DIU 385p 4508 24 Male Female 9 50 2x32 waySt Pin 230 275p 2x12 way Vic 20 350p gramming i 2 32 Ang Pin 275p 320p ax ii S m i i 3x32 t 260p X23 way Continuous display of current addresses as they are TEXTOOL ZIF DIL HEADERS 3x32wayAng Pin 375p 400p 2x25 way 29 2 being programmed SOCKETS 24 5 75 od 2 Tipe 1OCSR 8278p A C3S0p 2x28 way Spectrum 200p 28 pin 8 00 40 pin 9 75 me For 2 x 32 way ple ify spac 36 way 250p 40 y please spec p The programmer comes complete with cables software amp pn 50 TP ing C fae operating manual DIL SWITCHES 24pn 100p gt 5 aed 2x43 w8y 395p 89 2 50 carriage Software on disc 2 extra 4 way 70 8 way 130p 28 200 14 pin 375p 16 pin 400p 1x 77 way 400p 6 way 100p 10 way 150p 40pin 200 40 pin 10 30 2x50 way s100cenn 600p 4 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com EIE 74LS292 900 Jaara 1209 74LS293 120p LINEAR ICs COMPUTER COMPONENTS MODULATORS 7401 442827 74152927 6M
202. Ives Cambs designed and built in Britain 17 4BG Tet 0480 63570 VIDEO TERMINAL BOARD 80 characters 24 lines 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 EPROMs Full scrolling at 9600 baud with 8 switch selectable rates 5232 interface Bare board with 2 EPROMS and program listing 48 plus VAT Send for details or CWO to AAA ELECTRONICS AM Electronics Wood Farm Leiston Suffolk IP16 4HT Tel 0728 831131 CIRCLE 17 FOR FURTHER DETAILS 86 A Quick neat andeasy it s so easy and tidy with the Easibind binder to file your copies away Each binder is designed to hold six issues and is attractively bound and blocked with the WIRELESS WORLD logo Price U K 4 30 including postage packing and Overseas orders add 35p per binder Nat Giro No 5157552 Please allow 3 4 weeks for fulfilment of order Payment by ACCESS BARCLAYCARD VISA Send coupon below detailing credit card and signature Why not place your order now Send the completed coupon below with remittance payable to Easibind 42 Hoxton Square London 1 6NS Order Form WIRELESS WORLD enclose P O cheque value S foras vo binders Years required ae 4
203. LL ROAD EAST BIRKENSHAW BRAOF ORD 8011 2ER TEL 0274 684007 WANTED REDUNDANT TEST EQUIPMENT RE CEIVING AND TRANSMITTING EQUIPMENT VALVES PLUGS SOCKETS SYNCHROS ETC 848 Six channel chart recorder with six colour facility 59 Twin pen recorder with semi conductor amplifiers 2mV 20 V I ranges 98 Variable AC PSU two meters 25A 50v transformer so lated 69 Decade capacitance box predsion 1 11 total migofarads 49 Low ohms meter 29 Sweep generator Signal Generator Stab psu s Teieprinte Lab microscope 89 6 v 8 A rechargeable batteries make portable search lights 5ea FM AM Generator Tektronix Cali brator Fibreoptic light supply variable intensity Centrifuge Infra Red Gas Analyser variable stabilised EHT supply Tektronix Waveform Gen erator Pye Megohmmeter TV Sweep Generaror Water Conductivity Meter Akratork Torque Guage Video Oscillator 7 track postable recor der Record 4 chart recorder 49 Singie to 3 phase converter Dissolved oxygen meter NiCad charger FM AM Modulation Meter 0403 76236 2016 HNC Electronics See yourself in video If you re a qualified electronics technician keen on video and want to work in the world of video production talk to Unipart We keep all our customers and staff in the picture about promotions news training etc through our own exciting Channel 5 video communications package Right no
204. LOAD WATTMETER CT214 30 400mc s 20 200 watts meter indication 50 75 ohm 55 MAR CONI TF142E Distortion Meas Set 45 also TF995 A2 CT520 Sig Gens 1 5 220Mc s AM FM with book 100 RADAR RANGE CAL CT379 mains 45 X BAND RESONATOR direct freq cal 9170 9470 with 0 to 100 Db var atten meter indication 23also X band Tx loads WG 15 est 50Kw PK 25 POWER amp DRIVE UNIT for 240v provides 12v at 5 amps or 24v at 2 5 amps DC stab and RF O P at 10 cyrstal freq in range 2 8 Mc s O P 0 to 2 watts into 50 ohm all transis tested 55 ELEC BRIDGE TESTER for 200 250v provides earth neutral test or neutral to ext earth or can be used as ext bond tester as balance meter with cal poteniometer 0 5 ohms in carrying case with leads 25 CON DENSERS Sprague 2700 Uf at 250v size 51 2X3 with insul case heavy duty type new 3 50 ea 6 for 18 ARMY AERIAL KITS with 30ft 1 mast 10 sections plus 2x16ft whips with guys stakes insulators carrying bagetc can be used asvert Ae or mastnew cond 46 DEVIATION METER TF934 CT219 mains operated freq 2 5 100Mc s meas deviation 0 to 75Kc in 3 ranges with book 55 TAPE RECORDERS MOD EMI model RE301F two chan table version 65 Ferrograph Series4 two chan in small racks 85 also Series 6 single chan new cond with book 85 ELEC BELLS 6 dia 24v DC new 11 50 SOLENOIDS for 12v DC new 3 80 ea METER mains voltmeters 200 300v circa Jackfields Cables Connectors and Wiring Aids inthe new FFD C
205. Literature received 8 1 Uosat Il relocated joint tv Data collected froma and telephone cable recent computers in the New products cellular radio start classroom exhibition Sen computerized dictionary satellite weather map This issue has been affected by the continuing receiver network between members of the National Union of ists and controller 1 We se to readers and advertisers published on 15 August WWW americanracdiohistorv com Adelson M 1 T ysis an andan an displas gt Kosi4 by Spams Bhawan Sh anker p Watkinson Front cover pictures David Read s PAL colourtv enhancement board also pictured on page 37 comprising PAL modifier and comb filter decoder NEXT MONTH Laboratory equipment for measurement in linear motion includes a computer to air interface Detection of rider position enables RML computer to carry out experiments and display results In Stage Lighting System forty 1 kilowatt circuits are remotely controlled with one cable linking desk and dimmers A Z80 multiplexes data from the controls Dr Ken Smith of Kent University contributes a short series on power supply design concentrating on the switched mode variety And John Adam s SC84 switch regulated power supply is suitable for any application requiring an efficient simple and economical power unit with either fixed o
206. NMENT OVER 11 000EA eSTATICINVERTORS 12 or 24 VOLT INPUT 240 VOLT AC SINEWAVE OUTPUT VARIOUS WATTAGES e XY PLOTTERS AND RECORDERS VARIOUS e FERROGRAPH SERIES 7 RECORDERS MONO 100 STEREO 150 e LOW NOISE AMPLIFIERS 500MC S TO 40G CS IN VARIOUS RANGES MADE BY WATKINS JOHNSON 110 OR 240 VOLT MAINS INPUT 25 TO 50 SIGNAL GENERATORS VARIOUS 995 80 TF 2015 10 5 510 5 AM and FM 675 e TF 8010 85 10 485 5 100 e TF144H 100 e TF 1060 2 75 AND B 100 B 150 HP608 100 HP614A 2100 e HP618B 100 e HP620A 100 e TELONIC SM 2000 SWEEP GENERATORS L3 and L5 PLUG INS 4 TO 75MC S 60 TELDNWIC SWEEP GENERATORS 2003 850 TO 2150MC S 275 TF1313 BRIDGE 100 e TF791 DEVIATION METER 100 TF893A POWER METER 50 AERIAL MAST ASSEMBLY 30FT HIGH COMPLETE WITH 16FT WHIP AERIAL TO MOUNT ON GUYROPES INSULATORS BASE AND SPIKES ETC IN HEAVY DUTY CARRYING BAG NEW 30 e RACAL FREQUEMCY COUNTER 836 250 e TEKTRONIX PLUG INS 1A1 50 1A2 40 1A4 100 M 50 All items are bought direct trom H Government being surplus ecuip ment price 15 ex works S A E for enquiries Phone tor appointment fc demonstration any item Also availability change VAT AND CARRIAGE EXTRA EXPORT TRADE ANO QUANTITY DISCOUNTS GIVEN JOHN S RADIO WHITEHALL WORKS 84 WHITEHA
207. OM PLETE WITH ISB ADAPTOR ARU10A 100 WITH MANUAL CREED 75 TELEPRINTERS FITTED TAPE PUNCH GEARBOX FOR 50 AND 75 BAUDS 110 01 7 AC SUPPLY IN ORIGINAL TRANSPORT TRAY SEALED IN POLYTHENE LIKE NEW 15 EA REDIFON TT11 AUDIO TELEPRINTER CONVERTOR RECEIVER SOLID STATE SUPPLY 110 OR 240 AC MAQE FOR USE WITH ABOVE TELEPRINTER ENABLING PRINT OUT OF MESSAGES RECEIVED FROM AUDIO INPUT OF COMMUNICATION RECEIVER 15 WITH CIRCUIT TESTED REDIFON TT10 CONVERTOR 5 ABOVE BUT INCLUDES TRANSMIT FACI LITIES 20 e OSCILLOSCOPES STOCKS ALWAYS CHANGING SELAB S 111 SOLID STATE 18MC S 175 COSSORCDU150 35MC S 200 e TELEQUIPMENT 075 50MC S 300 TEKTRONIX 465 100MC S 1000 e SOLARTRON 01740 50MC S 300 e TEKTRONIX MAIN FRAME TYPE 7704 750 7504 600 7704A 1000 e FM RECOROER SANGHMD SABRE 111 14 CHANNELS 350 e TRANSTEL MATRIX PRINTERS AFTIR 5 LEVEL BAU DOT CODE UP TO 300 BAUDS FOR PRINT OUT ON PLAIN TELEPRINTER PAPER 50 to 100 e TRANSTEL AS ABOVE BUT ALSD 8 LEVEL ASC11 CCITT NO 2 AND CCITT NO 5 LIKE NEW 200 ARMY FIELD TELE PHONE SETS TYPE F L AND J LARGE QUANTITY IN STOCK 6 TO 15 OEPENDING ON TYPE AND QUANTITY AVAILABLE P 0 R DON 10 TELEPHONE CABLE HALF MILE CANVAS CONTAINERS 20 e MIGHT VIEWING INFRA RED AFV PERISCOPES TWIN EYEPIECE 24 VOLT DC SUPPLY 100 ORIGINAL COST TO GOV ER
208. OPPY DISKS MEET ANSI DIN ECMA IBM JIS AND SHUGART SPECIFICATIONS EVERY DISK IS CERTIFIED AND GUARANTEED TOBE 100 MINI FLOPPY DISK Sv 5i DISKETTES PRICEPER Certified for Single OR Double QUANTITY DISC Density media with hub ring 1 10 10 40 50 90 100 1 5 548 161 117 112 105 PRICES EXC VAT 01 05 5 481 170 123 117 110 MD2 DD S48tpi 2 00 144 137 1 29 MD1 DDS S96tpi 1 86 1 41 1 35 1 28 02 00 0 5 961 2 33 176 1 68 1 60 180 L 750 40 tpi suitable for 40 track 96 tpi Suitable for 80 track PRICE PER BOX OF 10 OF 10 CARRIAGE CHGS PLEASE SEND 2 FOR BOX OF TEN ANY QUANTITY ABOVE 10 ALLOW 5 FOR NEXT DAY DELIVERY per 100 23 00 VHS Beta 35 00 38 00 cat playing time Computer C15 15 minutes 24 00 Cassettes C20 20 minutes 25 00 High quality low noise cassette tapes Short play leaderless construction for use with computer cassette systems Each tape in individual plastic library case with index card HOW TO ORDER For disks all 50 per box of ten for p amp p First class mailfor small packets next day delivery for heavier ones For cassettes allow 5 carriage costs min order is 100 for next day elivery Post carriage costs include VAT P V TU BES E d Telephone Dept E 0254 36521 104 ABBEY STREET 0254 33611 ACCRINGTON LANCS BB5 Telex 635562 Griffin G for PV TO MANUFACTURERS WHOLESALERS BULK B
209. PROTECTION BATTERY with order Offer applicable to mainland UK only amp TEST LEADS INCLUDED TRADE ENQUIRIES INVITED FULL RANGE OF METERS ON APPLICATION Please allow 15 days for delivery CIRCLE 12 FOR FURTHER DETAILS Lynwood GD1 VDUs Intelligent Green micro controlled RS232 printer port 101 key Full Video ONLY 149 15 5 Burroughs MT686 7 TD710 Intelligent Green 12 VDU with 3micros and 64K store RS232 Programmable Only 199 new or 149 S H 15 P amp P Videcom Apollo VDUs Stylish 15 Green Z80 controlled VDU with printer port and lots of very advanced features Only 399newor 249 S H 15 P amp P Centronics 306 Line printers Professional fast 120 cps superb d 80 column printer Parallel i f ONLY 99 15 00 Computhink Act 800 Computer system Dual floppies eon and lots of business sane tine emen NLY 1200 RADFORD Audio Measuring Instruments Audio Amplifiers Loudspeakers and Loudspeaker Components for the professional and enthusiast RADFORD AUDIO LTD Diablo 630 heel rinter Diablo Hitype 2 Daisywheel Tractor unit Calcomp 565 Drum Plotter Othou steps _ ONLY 450 10P amp P 10 BEACH ROAD WESTON S MARE AVON BS23 1AU BECKENHAM PERIPHERALS Callers welcome N
210. RN IEL L 1 0024241 247 24 2441 dT HEN BBR INT 24 COND 24 ALLURE WARNING z EVIE INL TURNS 4203 341 5447 0 ST 2 Dub Renae C24 45 MIP EVIE 34 2 GUTU THA LONLA JOIE MIHI 450244 L 4G0SUB341 4000 T TURN L 600 Or EVIE UI X 34 2412240 214010240510 622241 te Sal 21450105 eo 734 92434 0 CIO TURN LEID TU 4 347 GOT OD 62st 34p 34 340 134 344 AAD 3450 105 2452714 641224124 41124 17075 45 Fig 1 Line interface and auto answer section Isolation from the line is via a transformer and for the ring detection cir cuit an opto coupler An auto dialler could be added by the user if required MULTI STANDARD MODEM Other useful options include the ability to send Xon and Xoff commands to halt temporarily the output from the distant compu ter and to echo incoming charac ters back to it this allows the other operator to see what he is typing There may be some advantage too in redefining the output of certain keys on the key board In particular the effect of the delete key seems to vary from one computer to another For Viewdata systems such as Prestel it is convenient to have the return key send a character Some of the bulletin board systems listed here have adopted the so called Christensen or Xmodem protocol
211. RTER 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 1 1 01 661 3130 MICHAEL DOWNING 01 661 8640 ASHLEY WALLIS 01 661 8641 Northern Sales HARRY AIKEN 061 872 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 International Agents and the Advertisers Index appear at the back of this issue 01 452 1500 Lro 01 450 6597 ACCESSORIES BasicllRom ws 02000 Rer BBC Micro Computer System View Word Processor Rom 2 52 00c Disc Cable 6 00d Wordwise W P 34 00 DoubleDiscCable 8 50d OFFICIAL D EALER ACORN COMPUTER SYSTEMS BCPLROM Disc 87 00b 3M DISCS with Lifetime Warranty eres BBC Model B 5346 00 Disc Doctor Utility Rom A s ER Of Please phone for availability BBC Model Econet 389 00 TermiEmulatorRom 528004 40 05 522006 BBC Model B DFS 8428002 U TRACALCRom BBCPublications 6500c SOTSS DD Pitot 10 poe BBC Model B DFS
212. Road Teddington Middlesex TW11 8LL Telephone 01 943 4477 Telex 23920 Euhire CIRCLE 64 FORFI FURTHER DETAILS TOROIDAL TRANSFORMERS We are now able to offer a range of high quality Toroidal transformers at very competitive prices 30VA 6 27 50VA 7 73 80VA 8 51 120VA 9 33 160VA 11 43 300VA 15 27 Prices include P amp P and VAT Available in the following voltages 6 0 6 9 0 9 12 0 12 15 0 15 18 0 18 22 0 22 25 0 25 30 0 30 35 0 35 40 0 40 45 0 45 50 0 50 Qty discount 50 plus 10 100 plus 20 TRADE ENQUIRIES WELCOME AIRLINK TRANSFORMERS LTD 28 Bullfields Sawbridgeworth Herts Tel 0279 724425 137 Standard Ranges in a variety of sizes and stylings available for 10 14 days delivery Other Ranges and special scales be made to order Full Information from HARRIS ELECTRONICS London 138 GRAY S INN ROAD W C 1 Phone 01 837 7937 Telex 892301 __ CIRCLE 27 FOR FURTHER DETAILS CIRCLE 63 FOR FURTHER DETAILS 20 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com Clifton Chambers 62 High Street Saffron Walden Essex CB10 1EE Telephone 0799 24922 Telex 818750 CIRCLE 46 FOR FURTHER DETAILS 25289999 Continental Specialties Corporation 100 MHZ Frequency Counter Instant frequency indication from 5Hz to 100MHz no range selection problems brilliant 8 digit LED display mains o
213. S amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com Continued from page 62 the p s d the output voltage changes to drive the v c o to the new frequency Operation of the phase locked loop is exactly analogous to a servo loop it has a natural fre quency damping factor and a bandwidth witha second order low pass filter characteristic Effectively what the 1 1 does is to recover from the frequency of the input signals the original changes in voltage that drove the in the modulator As the of the 1 1 is identical to that of the 566 it is not surprising that the changes in voltage levels at the output of pin 7 are similar to those applied to the input of the v c o of Fig 6 The voltage change applied to the v c o of the modulator was 430mV 13 33 12 9 the voltage output from the 565 pin 7 is thus of the same order maximum operating vol tage of the 565 i c is 26 volts It cannot therefore operate from the 15 volt supply rails and was con sequently chosen to operate from the 15 volt supply rail and ground 15 volt supply rails were chosen because of the large voltage drive required by the tri angle to sine wave converter of Fig 6 it will not operate satisfac torily from 12 volt supplies The two inputs of the 565 1 pins 2 amp 3 require an identical d c bias that is slightly less than the half supply voltage The poten tial divider consisting
214. SAE DIGITAL MULTIMETERS UK C P amp ins Bench type 1 00 Hand held 5 PROFESSIONAL SERIES d Thandar Bench Portables 355 3 digit LED 29 ranges 10 AC DC 20 Meg ohm 0 25 basic 85 TM356 314 agh LCD 27 ranges 10A 0 20 Meg ohm 0 25 basic TM3SI 41 digit LCO 29 ranges 10A Lr 20 Mag ohm 0 1 basic Optional carry case 5 95 Thuriby Bench Portables x Optional carry case 18 00 1503 43 digit LCO 0 05 basic 10 resolution plus frequency maasurament up to 4MHZ AC DC 115 00 10 Amps 159 00 1503 47 digit LCO as above but 0 03 basic 175 00 1054 4 digit LCO True AMS version 185 00 1905 5 2 it Intelligent multimeter resolution D ols basic 325 METRIX HAND BENCH PORTABLES ITT Size 188 x 86 x 50mm Rotary controls MX522 34d It LCO 21 ranges 10A AC OC 2 ohm Basic 0 5 67 00 MX562 3 digit LCO 29 ranges 10 AC OC 20 ohm Basic 0 2 Plus continuity tester 95 00 M X563 True RMS 314 digit 30 ranges 10A AC DC 20 Meg ohm 20HZ to 2 0 1 basic 155 00 MX575 41 digit True RMS 21 ranges 10A 0 up to SOKHZ 0 05 basic 175 00 HAND HELD MODELS Controls S Slide R Rotary Push button All feature AC OC volts OC amps many with AC amps ohms etc UK C P 5 ALL MODELS WITH CARRY CASE 025 12 range 024 OC 2 Meg ohm 5 24 43 K0305 14 range 10A 0 2 Meg ohm 5 24 30 KD30C 26 range A
215. SINGLE CHANNEL AMPLIFIERS TSS4663 Gain 28 46dB adjustable Maximum output 63dBmV Power requirement 14V 170mA TSS3062 Gain 12 30dB adjustable Maximum output 62dBmV Power requirement 14V 26mA DRIVER AMPLIFIERS TS1030FM FM driver amplifier 1048 Gain Maximum output 3048 Power require ment 14V 10mA TS103083 Band 111 driver amplfier 1048 gain Maximum output 30dBmV Power requirement 14V 10mA TS1030UHF UHF driver amplifier 1088 gain Maximum output 30dBmV Power require ment 14V 10mA 1510405 Single channel UHF driver amplifier 1048 gain Maximum output 40dBmV Power requirement 14V 10 Quote channel required DISTRIBUTION AMPLIFIERS TE2042 Domestic distribution amplifier 1 input 1 output Gain 2048 Maximum output 42dBmV TE1638 Domestic distribution amplifier 1 input 2 outputs Gain 1698 Maximum output 2 at 38dBmV TS2046 40 860MHz Gain 2048 1888 VHF Maximum output 46dBmV TS2846 40 860MH2 Gain 2888 UHF 2248 VHF Maximum output 46dBmV TS2845 Separate UHF UHF inputs Gain 28dB UHF 22dB VHF Maximum output m 752054 40 860MHz Gain 2048 UHF 1848 VHF Maximum output 54dBmV TS2060 40 860MH2 Gain 2048 1848 VHF Maximum output 609 CHANNEL CONVERTERS 155865 Gain 5508 UHF 5588 VHF 4248 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 requir
216. Schottky gate with a very fast rise time so the loading of data is assured With this data stored in the shift register the trailing edge of the carry pulse loads a new value from v d u memory into and the cycle repeats This means that pixel output begins two char acter periods after the start of a scanning period As mentioned earlier the controller also sup plies some direct tv Junction of R 127 amp 270k on tv p c b 220 2N2369A d To pad ontv p c 1k from which Ry was lifted HSYNC 1k du EE as From end of R72 in tv tv signals one to enable the display so that the screen may be blanked during non display peri ods such as during flyback and a second to indicate when the char acter position being accessed corresponds to the setting of the controller cursor register As with M lines these signals will be del ayed and taking the example of the display enabling signal they must be delayed by one and a bit character periods if they are to become active just as pixels for the first character on the line are clocked out of the shift register One enhancement made to the Hitachi 6845 is that it is possible to delay the output of these two control signals by one or two character periods which saves on i cs These signals are given a one character period delay and syn chronized by a two bit latch ICs which is also clocked by
217. UCC Micro Film Reader Cassette Type 35 Marconi Transmission Line Test Sel Type TF 1267 40 Marconi Variable Attenuator 7 5ohm Type TF 1073 25 20 60 amp Alternator amp Generator NoiseF iller 1 00 Instrument Fans 4 1 2 x 41 2 240 110 1 50 each Garrard Car Cassette Player Mechanisms Stereo Head 2 50 Tektronix Oscilloscope Probes 10 each Pye Rx Ni Cad Batteries 3for 1 00 Mullard Vari cap TV Tuners Type ELC 2003 Ex Brand New Sets 3 50 Pye Cambridge Vanguard 18 Way Control Leads 400 Sony 1 2 Video Tape 5 Reels 200 BNC Plugs 75 50 IC Test Clips 28 pin 4 40 pin 2 Circulators 590 720 Mhz N sockets 25 Transistors Type 2N3055 4for 100 Transformers 30 volt 2 1 amp 100 Transformers 36 volt amp 1 Samp 100 Transformers 600 0 600 250mA pius 460 0 460 230mA 1000 Variac 2 5 amp 8 amp 15 amp 20 25 amp Loudspeakers Richard Allan Type 12 12 150hm 6 00 Semiconductors at 5p each 128 65 BC173C 8 328 149 113 12 ZTX213 R2517 184007 P amp P or Carriage and V A T at 15 on total must be added to ail METEOROLOGICAL BALLOON orders Callers very welcome strictly be tween 9 a m and 1 p m and 2 and GEC RECEIVERS with Water Activated Battery contains 5 p m Monday to Friday inc all weather sensors fully solid state 5 Model BRT 400 120 ea
218. UIT iN FAIR USEO CONOITION RACAL SYN THESISERS FREQUENCY GENERATORS MA350B SOLIO STATE FOR USE WITH 79 RA217 1218 ETC 100 10 150 250 1 6 5 10 31 6MC S 100 e MA1350 FOR USE WITH 17 RECEIVER 6100 to 150 2596 PRECISION FRE QUENCY STANDARD SMC S 1MC S 100KHZ 10010 150 PANORAMIC ADAPTOR RAGE 150 RA137 LF CON 10 TO 980 5 75 218 INDEPENDENT SSB UNIT 50 RA153 AND RA 253 TWIN CHANNEL RECEIVER 1 TO 30 MC S THIS IS VIRTUALLY TWO 1175 iN ONE CASE 150 to 200 RA1218 SOLID STATE RECEIVER WITH ELECTRONIC FREQUENCY DISPLAY TO 1082 FREQUENCY 1 TO 30 MC S 500 RA6217 RECEIVER SOLID STATE COMPLETE WITH SEPARATE SYNTHESISER INCLUDES FM A VERY HIGH GAIN SENSITIVE AND EXTREMELY STABLE RECEIVER NORTH AMERICAN RACAL MADE 400 RA337 LF CON VERTOR 3 TO 980KHZ FOR USE WITH SOLID STATE RECEIVERS 150 e EDDYSTOME COMMUNICATION RECEIVERS 958 SOLID STATE HIGH STABILITY 100KH7 TO 30MC S 350 to 400 EC964 7K SOLID STATE SINGLE CHENNEL SBB MAINS OR BATTERY 1 6 TD 27 5 5 AND 400 to 535KHZ 100 WITH MANUAL PLESSEY PR1556 SOLID STATE 60 5 30 MC S 400 REOIFON SSB RECEIVER R499 SOLID STATE 10 FIXED CHANNELS RANGE 1 5 TO 30MC S AND 255 2 TO 525KHZ MAINS OR BATTERY C
219. UP 10 8 16 50 18 MIDRANGE 10 8 100 MID 25 MAJOR 12 46 16 30 16 12 85 30 26 WOOFER 12 8 80 HI FI 25 AUDITORIUM 15 8 16 6 Woofer 37 DISCO GROUP 12 4816 4 16 DISCO GROUP 12 4816 7 PA 20 DISCO GROUP 12 8 16 100 PA 26 DISCO GROUP 15 8 16 100 PA 35 REPAIR service to most Baker loudspeakers SPEAKER COVERING Samples S A E CABINET WADOING 18in wide 35p ft MOTOROLA PIEZO ELECTRIC HORN TWEETER 3 in square 5 100 watts No crossover required 4 8 16 ohm 798 x 3l in 10 HORN BOXES complete 200 watt 30 300 watt 35 Size 16x6x6in Black vinyl covered with handle Post 4 CROSSOVERS TWO WAY 3000 c s 30 watt 3 60W 3 50 100W 4 THREE WAY 950 cps 3000 cps 40 watt rating 4 60 watt 6 100W 10 LOUDSPEAKER BARGAINS Please enquire many others in stock 4 ohm 7 x 4in 2 50 6 2 8x 5in 3 8in 3 50 70W 16 ohm 2541n 3in 2 5x 6 x 4in 7 x 4in Sin 2 50 3in 10W 4 8x5in 3 Bin 4 50 Win 5 121 6 25W 6 50 60W 13 50 15 ohm 2Vun 3Van 5x 3in 6x 4in 2 50 62in 10W 5 8in 4 10 7 25 ohm 3in 2 5x 6x 4in 7 x 4in 2 50 120 ohm 3an d a 1 EMI 13 2x8in Bass amp Tweeter 4 or 8 ohm 10 watt 8 pp 1 Dept 1 337 WHITEHORSE ROAD CROYDON Open 9 6 Closed all day Wed Sat 9 5 Books and Components Lists 32 stamps Minimum post packing charge
220. UYERS 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 HENSONLTD 21 Lodge Lane North Finchley London N 12 5 minutes from Tally Ho Corner 1613 ARTICLES FOR SALE BRIDGES waveform transistor analysers Cali brators Standards Millivoltmeters Dynamome ters KW meters Oscilloscopes Recorders Sig nal generators sweep low distortion true RMS audio FM deviation Tel 040 376236 1627 Townley Times FREE Mail Order newspaper of Bargains Relays Diodes Thyris tors Capacitors Resistors Bridge Rectifiers Cable Straps High Speed Fuses and Mechanical Components Harehill Todmorden Lanes OL14 5JY Tel Todmorden STD 070 681 4931 2530 100 HI FIREVIEWING need a young person to help me test hi fi products during June July and August 1984 Pay around 80 wk You must have an interest in hi fi and music a knowledge of electronic principles and minimum qualific ations of O Levels in a science subject and English C
221. Videotimebas correction television sound EP8000 and EP4000 EPROM Emulator Programmers 1 Software personality programming of NMOS HMOS CMOS EPROMs both single amp triple rail up to 16k x 8 bytes EP8000 Expandable to program PROMs with BP5 Signetics PROM adaptor Emulation of all EPROMs up to 8k x 8 bytes with the EP8000 and up to 4k x8 bytes with the EP4000 No personality cards or characterisers required Use as stand alone programmer slave programmer or EPROM development System 1 Checks for misplaced reversed inser tion and shorts on data lines EP8000 Memory mapped video O P in addi tion to LED display allows full use of powerful editing facilities including block Byte move insert delete match highlight shift define displacement calculation Comprehensive O RS232 serial port parallel port Ex stock EP8000 8k x 8 RAM 695 12 del VAT EP4000 4k x 8 RAM 545 12 del GP Industrial Electronics Ltd Unit E Huxley Close Newnham Ind Estate Plymouth PL7 4JN CIRCLE 001 FOR FURTHER INFORMATION Programming Systems from Stock revesttsie I3 ti jkluis P8000 Production EPROM Programmer Programs NMOS HMOS CMOS EPROMs up to 16k x 8 bytes both single amp triple rail No personality cards or characterisers required Up to 8 EPROMs programmed simultaneously Simple menu driven operation
222. Why ILP 3 t 110 x 50mm 2 6K 9x017 30 30 1041 Regul 18 Regulation 8 9 Ex stock delivery for small egulation 18 34010 6 6 664 2 3 Regulation 6 9x018 254395 892 4 IY 4 E x01 9 8 89 d 9x026 40 40 78 quantities 1x010 6 6 250 3 011 9 9 444 5 012 666 7 013 15 75 1000 R 12017 9 9 166 3 012 12 12 333 5x013 533 72014 8 18 aga 3 063 25452 634 Gold service available 21 days o Pn 125 215 256 4 44404 122422 91042 55 55 5 68 manufacture for urgent deliveries 5 222 9 028 110 5 68 2 1x014 083 25015 2522 320 7x01 30 30 500 95029 220 284 5 year quibble guarantee E 0 48 3017 30 30 33 D 206 12018 25505 428 9 030 240 260 Realistic delivery for volume 13017 050 33028 10 A 5x026 200 7x025 45445 333 orders 1030 133 45 7x033 50 50 3 00 No price penalty for off 072 7x028 110 272 orders 0 66 7x029 220 136 21 7x030 240 125 Prices including P amp P and VAT Mail Order Please make your crossed VA Size Size cheques or postal orders payable to ILP Post to ILP Electronics Ltd Dept 3 15 0 7 43 160 5 1290 Electronics Ltd Graham Bell House Roper Close 30 i 15 08 225 E 1630 Trade We will open your credit account Canterbury Kent CT2 7EP 80 3 1081 500 8 2673 immediately upon receipt of your first Tel 0227 54778 Telex 7 120 4 1173 625 9 3163 order 965780 For 110V primary insert O in place o X in type number For 220V primary Europe insert
223. X510 ZTX531 ZTX650 ZTX651 ZTX652 ZTX653 2TX750 ZTX751 ZTX752 27 753 IN34A 1821 14823 14914 9916 1 4001 44002 144003 144004 144005 14006 144007 144009 INA150 14448 146400 INS401 1 5402 15404 1 5406 145407 5 102 115 BA133 BA138 BA142 BA155 BA156 BA157 158 159 BA182 BA20 BA202 16 8A317 BA318 BAX13 88105 881096 BY126 CIRCLE 69 FOR FURTHER DETAILS WWW _ americanradiohistorv com ELECTRONICS amp WIRELESS WORLD JULY 1984 SCR s TRIACS DIACS THYRISTORS 4 8 amp 12 Amps Texas T0220 Suttix A 100V B 200V 300V D 400v M 600V 4 TIC106A 49p TiC106B 51p 06 TIC106D TIC106M 8A TIC 16A TIC116B 16 TIC116D TIC116M 12 TIC126A TIC1268 TIC126C TIC126D TIC126M TRIACS Texas 400 70220 Case TIC206D 4A 69p 2250 6 79p TIC2260i8A 92 TIC2360 12A 1 25 TIC246D 16A 1 35p TIC253D 20A 1 99p TIC263D 25A 2 25 DIACS many inc specials see our E24 Series 2410 47V 13 Wan E24 Series 3 3 to B2V BRIDGE PIV shown in brackets 1 2amp wo1 100 WO212001 WO41200 08 800 2 amp type Square with hole 501 100 5024200 04400 508 800 6 amp type Square with hole PWO01 100 95 PWO020200 99 041400 1 300 PWO6 600 139p 25 amp type Metal clad with hole 011100 2 62 02 200 275 041400 3 25 K06 600 BYW64
224. Xmodem protocols and numerous other features Current versions have a Prestel mode which supports colour Viewdata graphics including double height characters and can download telesoftware The price is 34 including v a t Software for the TRS 80 is available from Molimerx Ltd who offer two communications packages Smart Terminal at 25 30 and Modem 80 at 30 48 communications program to run under CP M 80 is available to members of the CP M User s Group Details in return for a stamped addressed envelope from the group at 72 Mill Road Hawley Dartford Kent Individ ual membership costs 7 50 per year Logging on First select the appropriate sig nalling standard and mode using 5 and 5 At this stage S should be in the centre off line position Dial up the computer of interest and when its answering tone is heard move S to the on line posi tion This will establish commu nication disconnecting the tele ELECTRONICS amp WIRELESS WORLD JULY 1984 phone handset at the same time With some of the bulletin board systems listed in the box it may then be necessary to type a few carriage returns to start things off At the end of the call S should be moved back to the centre posi tion to break the connection In the Viewdata mode disconnec tion occurs automatically when the Prestel computer drops its carrier This may happen prema turely if the RTS signal is removed as this may occur mome
225. Y BACK GUARANTEE Part of our value 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 NG OF E IG HT including instruction card power supply and carriage 395 VAT 454 25 esa Lombard House Cornwall Road Dorchester Dorset United Kingdom Telephone Dorchester 0305 68066 Telex 418442 CIRCLE 58 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com 35 CABLE T V HEAD END AND REPEATER AMPLIFIERS SINGLE CHANNEL AUTOMATIC GAIN CONTROL AMPLIFIERS TAG4863 Gain 4898 maximum output 63dBmV Regulator or 898 Power requirement 14V 210 TAG4063 Gain 4088 maximum output 64dBmV Regulator or 1698 Power requirement 14V 210mA
226. a nominal value of 12 90V Thus by switching the transistor on and off the voltage on pin 5 is modulated by 10 about its centre value of 13 125V The input stage to the transistor has been designed for either t t 1 levels between 0 and 5V or RS232 type signals 3 to 4 15V If both types of input are required there is no reason why two tran sistors should not be used with their collectors sharing a common 39k resistor It is of course important that the transistor of the unused input be in its off state 1 non conducting Apart from the voltage on pin 5 the frequency determining components of the 566 i c are the 9 1k ohm resistor on pin 6 and the 3 3nF capacitor on pin 7 With these chosen values the output frequency for a voltage of 7 8 5 is f 1 2 4RC i e 9990Hz Thus when the logic level on the input varies between low and high the frequency out put of the 566 i c varies between about 9 and 11kHz output from pin 4 of the 566 i c is a symmetrical triangu lar waveform of about 3V pk pk with a positive d c bias voltage The triangle to sine wave con verter needs quite a large voltage drive and the variable gain stage is included for this purpose The tri angle to sine wave converter uses the non linear Ips Vps transfer characteristic of a p channel j fet to shape the trian gular waveform The output from it is a little less 1V r m s witha distortion factor of less than
227. ach over and to trills and glissandi without prob lem Negative going interrupts can be produced by taking the strobe lineto the non inverting input of a comparator whose input is biased just below 2 5V so that it responds only to negative going pulses and to the inverting input of a further comparator whose non inverting input is at just above 2 5V which responds only to positive going pulses The LM393 dual comparator is ideal for this purpose since it works with a 5V supply and has open collector outputs which can be wired together to produce OR gat ing Figure 2 is the final circuit Resistors R provide bias for the strobe rail and R and C are R and C for each key Fig 1 Resistors provide bias for the comparators IC Resistor R forms collector load and resis tors Rs ss provide some hystere sis usually a good policy when using comparators to improve noise immunity and switching times and to reduce tendency to spurious oscillations The input voltage on IC must not be allowed to fall below ground and it can be seen from Fig 1 that the strobe rail can do this hence Continued on page 29 Switch opened Switch closed Fig 1 Outline of the keyboard s interrupt generator Closing or opening the switch causes the voltage on the strobe rail to act as shown Each pulse causes an interrupt Any key changes state Interrupt generated on CBI
228. aking use of obsolete 405 line v h f television transmitters which can be modified for this type of work IBA have already donated several Band III equipments to hospitals in Aberdeen Bristol and Cambridge and have earmarked further equipments for this purpose when Band television is finally phased out in January 1985 Telecommunicati ons Act The Telecommunications Act 1984 received Royal Assent on 12 April 1984 and Part VI provisions relating to wireless telegraphy incuding amendment and enforcement of the Wireless Telegraphy Acts will shortly become law The new Act appears to provide the DTI with the means of stamping out unauthorized and illegal use of transmitters of all types provided always that sufficient effort is put into tracing them Manufacturing selling offering for sale or hire of restricted apparatus becomes forthe first time an offence Having without reasonable excuse such equipment in one s custody or control or importing it will also be an offence Manufacturing includes assembly of component parts Immediate seizure of equipment under a search warrant becomes possible if there is any doubt as to identity or address not even a warrant is necessary Where such seizure is later confirmed by the Court the Secretary of State can as at present dispose of it as he thinks fit The Act also makes pro vision for payment of the radio Interference Service from money provide
229. al Voltmeter Pantechnic present the most adaptable high powered amplifier ever oe 453 605105 9318 959 00 Tektronix 7403N Main Frame 750 00 HEWLETT PACKARD SYSTEM Hewlett Packard 182A Main Frame550 00 431 Power Meter 75 Features Hewlett Packard 182C Main Frame395 00 8052 Impulse Sound Level Meter200 00 HIGH POWER up to 1 2kW single ended Hewlett Packard 182A 4 Channel Plug In a Broadband Sampling LOW VOLUME s Cubic foot inc Heatsink and MmeBase igi 75 ats Generator 1000 00 3480A Digital Voltmeter 135 00 VERSATILE Delivers more than 1kW into 108 ohms Telequipment D83 50MHZ 1900A Pulse Generator 1925A Word OR 2 600W into 21080 Dual Trace 450100 144 4 St dad R4 x W in i arconi andar X 300W o 2 19 40 ANALYSERS cd um s Hewlett Packard Fourier Analyser 54518 Marconi 8010 Signal Generator 100 00 OR 1x 300W into 210 40 with 7900A Disk Drive and Low Pass Radiometer SMG1 Stereo 1 x 150W into 4 to 80 Filters A to D Converters Etc 2 500 00 Generator 250 00 Etc etc RHODE SCHWARZ Racal 9908 Counter Timer poene 500 00 Racal Universal Counter 9835 100 00 Having been closely involved in a wide variety of OEM applications of their amp SHF Signal Generator 17 to 5 0 A k boards Pantechnic became aware of numerous implementation problems often GHZ 850 00 mae Kerr Logarithmic LCR EU left untackled by other amp board manufacturer
230. allation and maintenance of communication systems preferably in Home Office Senior Wireless Engineer telecommunications training of vital national importance the field of mobile radio and be capable of the day to day supervision of a small section of technical instructors and administrative staff The post requires an officer with a good knowledge of telecommunication practice and principles including micro electronics and the capability of preparing and presenting courses which are essentially orientated towards the maintenance of telecommunication equipment coming into service because of the World Administrative Radio Conference WARC Frequency Conversion Programme Salary for this Stanmore based post will be within the range 10 575 12 660 including 500 Outer London Weighting according to qualifications and experience SALARIES UNDER REVIEW RELOCATION ASSISTANCE MAY BE AVAILABLE For further details and an application form to be returned by 13 July 1984 write to Civil Service Commission Alencon Link Basingstoke Hants RG21 1JB or telephone Basingstoke 0256 68551 answering service operates outside office hours Please quote ref T 6252 The Civil Service is an equal opportunity employer 2638 BORED 2 Then change your job 1 Electronics Test Engineer 8 500 280 and instrumentation and calibration Herts area 2 Bench Service Engineer 8 500 Hand held radio and allie
231. allycarry Carrickfergus N Ireland BT38 9LF Tel 09603 78330 MULTIBOARD COMPUTERS 29 v emo ocomputers CIRCLE 50 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com 33555515 Evary card winner vei 8C Bus system can for host of applications Process Con Ba ch Counting Robotics Colour Graphic Displays CAC CAM In Manufacturing Telecommunications Insirumentation Laboratory Testing Security Systems Plant Control Data Collection and Distribution Also in smaller companies it can handle Accounts Payroll Wardprocessing Stock Control Program Compilation and Data Base T Management whilst still being able to run specialist applications And because there is no wasted capacity with a Gemini a system can cost a good deal less than you might think With Gemini you ccn buy a complete system upgrade your existing 80 Bus system or build your own So when you ve had a look at the pack of cards below plug yourself into our dealer network o discover how opening a new pack of cards with Gemini will help you pick a winner T These represent just a small selection from the range of over 25 cards p GM813 CPU 64K RAM BOARD This card provides system 4 GM837 COLOUR GRAPHICS BOARD 256 X 256 sixteen MHz 780 CPU 64K user RAM and both serial and parallel colour graphics display Out
232. ample low power transmitters at major outdoor and sports events This may however be deferred until the end of the second session of the ITU Regional Administrative Conference at Geneva next October to December when frequency assignments between 100 108MHz are expected to be agreed for the European region Vienna Convention The events during April surrounding the siege of the Libyan People s Bureau were calculated to re inforce the very worst fears of signals intelligence people The American ABS network started the ball rolling by claiming that Libyan messages to London had been intercepted deciphered but then not passed on to the police in time for them to take greater precautions during the morning of April 17 Such a leak apparently from American sources if true must rank alongside the three classic occasions in the 1920s when it was openly revealed in the British Parliament that Russian diplomatic traffic was being read This led inevitably to the USSR introducing secure ciphers and WWW americanradiohistorv com theloss of a valuable source of information As a result British Intelligence became very wary of passing sigint even to the Cabinet 6 Today diplomatic traffic be unconditionally secure truly random one time keys or more often computationally secure requiring excessive computer time to crack Clearly some of what can be plucked form the air can still be read if o
233. and comb luminance filter of Fig 34 together with the optional sync separator sandcastle pulse generator and extra field blanking of Fig 36 Sound fc carrier ATTENUATION dB 4 6 FREQUENCY Mhz T T T ui preferred values 8 Scale up from 20015 GROUP DELAY ns 8 0 2 4 6 8 10 FREQUENCY MHz Errors caused by rounding components of Fig 87 bottom circuit to preferred values are shown by the group delay response above Fig 88 Input step rise tme 20015 overshoot 0 6 Group delay ripple and other losses in performance caused by using preferred capicitor values are shown in these pulse and step test results Fig 89 Half amplitude duration of input pulse 200ns overshoot 1 1 TELEVISION From sound trap see Fig 81 Chroma out to e g Pin3 TDA3561A Fig 93 Circuit of modified chroma path filter when using the better i f s a w filter Subcarrier equivalent frequency 35 067MHz is only 0 5 to 2dB down 75 AMPLITUDE dB a 66 6 8 10 FREQUENCY MHz Fig 94 Amplitude performance of the chroma path filter Limited This unit has a perform ance specification of Two video outputs at 75Q amplitude response 1dB to 5 5MHz balanced unbalanced sound outputs harmonic dis tortion 0 5 MAX u h f coverage channels 20 70 diffe
234. and switching points where the real intelligence and flexibility of the system resides The full range of services is available to all the switching points but pro grammes are only transmitted down the secondary links to each customer when they demand a specific tv channel or service It is envisaged that each wide band switching point will be able to service up to 300 customers with cable runs up to 500m Even though the Fibrevision trial used optical fibres for these secondary links it is considered that cost still favours small bore coaxial cables at least for the next few years Eventually the secondary links will also be optical fibres Each customer will be able to receive two simultaneous tv channels and a range of f m stereo sound encoded by frequency division multiplex on their 120MHz band width secondary link A customer termination unit a small set top u h f converter and a remote control handset completes the information control chain Where a super primary link to the super head end is relatively short it is intended to utilise 50um graded index fibre driven by a 0 85 semiconductor laser On the longer super pri mary links it may be necessary to use l 3um monomode fibre Each link will be composed of ten fibres There will be five fibres for a full range of off air and subscrip tion television with each fibre carrying four frequency multi plexed frequency modulated tv channels resulting in a to
235. aning Every batch of completed boards is is sued with a signed certificate of confor mity and quality 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 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 SERVICES PROM EPROM amp PLA Programming service from original device or list Most devices catered for Charges 2 25 per copy 5p per 16 bytes manually entered VAT extra S A E Appreciated M GAFFNEY 17 Solway Close Fearnhead Warrington WA2 OUP 2622 ANALOG COMPUTERS LIMITED CAPACITY NOW AVAILABLE FOR FOR THE BEST PCB SERVICE AVAILABLE Circuit Design amp Development Digital and Analogue xArtwork Layout PCB artwork layout and mechanical detailing P O approved standard xBoard Manufacture Prototype to semi production excellent rates Wiring amp Assembly assembly wiring and cable forming Flow solder ing facilites available Test Full test facilities available One or all services available Please telephone Chelmsford 0245 357935 or write to HCR Electronics The Industrial Unit Parker Road Chelmsford 30mins from Liverpool Street St 1169 SPECIALISED SUB CONTRACT SERVICES Custom Design
236. around cause Tr to be driven in opposition to Tr on the first beat of each bar to give an accentuated pip Time signatures of 2 4 3 4 or 4 4 are selected by a switch Supplies of between 5 and 18V may be used I used two PP3 batteries to give 18V in the prototype Steve Kirby East Molesey Surrey Microprocessor teaching aid Using the WAIT command the Z80 microprocessor can be made to execute one instruction at a time under control of a manual switch If all the address data and control lines are monitored the processor can be seen fetching storing information and carrying out commands While the switch is open WAIT is low When the switch is closed the upper bistable device is clocked and WAIT goes high Simultaneously pulses from the processor clock feed the lower bistablei c and after two rising edges the output of the lower device goes low and resets the upper one Thus WAIT returns low after one or two clock cycles and sets the lower bistable i c Note that dynamic memory content will be lost since the memory refresh circuit cannot operate The circuit has been used with a ZX81 no ram expansion connected through the 23 row connector to make internal soldering unnecessary A binary to hexadecimal converter and display on the data lines is a useful addition Peter Hall University College London Simple clipping detector No setting up is required on this simple clipping detec
237. atalogue m FUTURE FILM DEVELOPMENTS P O Box3DG 114 Wardour Street London WIA 3DG England Telephone 01 434 3344 amp 01 437 1892 Telex 21624 ALOFFD G Cables Allotrope London Wl CIRCLE 07 FOR FURTHER DETAILS scale size 4 sq new 15 also ameters DC 500 amps with shunt new 11 50 Collect items Aerials Pye 70 73 Mc s Ground planes new 10 ea Racks 6ft 19 with doors ex Vtrs 30 ea Above prices include carr postage amp VAT Goods ex equipmentunless stated new List 34 available on request A H SUPPLIES 122 Handsworth Road SHEFFIELD S9 4AE Tel 0742 444278 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com Hyperthermia progress Much attention in recent years has been focused on radiation hazards very close to high power radio transmitters Less notice has been taken of the advances being made in the medical use of r f heating by h f v h f and microwave transmitters particularly for hyperthermia treatment of malignant cancer tumours Although hospitals have used heating by r f power diathermy for about 50 years recent work has concentrated on the development of more effective coupling of the r f power into the affected part of the body by means of improved applicators A recent report from the Biomedical Engineering and Instrumentation Branch of the American National Institutes of Health in Bethesda Maryland notes that while hyperthermia offers
238. ate wherever situated the mission may employ all appropriate means including diplomatic couriers and messages in code or cipher However the mission may install and use a wireless transmitter only with the consent of the receiving State CUBE BBC SECOND PROCESSORS equivalent to the BBC Microcomputer Features include Real time clock CUBE BeebFLEX 6809 Second Processor Unit leaflet on our CUBE BBC Eurocard extensions is also available Control Universal Lt EuroBEEB EuroCUBE 65 6502 Second Independent Processor EuroCUBE 65 is 6502 multi function SBC CPU It is both a second processor and a stripped down industrial EuroBEEB is EuroCUBE with 16kB BBC BASIC Interpreter ROM and 8kB battery backed CMOS RAM memory on board Four RAM ROM memory sockets up to 16kB per device Battery back up for CMOS RAM and clock VIA providing 16 digital i o channels ACIA providing a bi directional RS 423 422 serial port The BBC Micro acts as an intelligent terminal file server to EuroBEEB Turnkey feature allows automatic power up and run CUBE bus connector for rack mounting with peripheral Eurocards Fully supports the FLEX operating system on the BBC Microcomputer Housed in self powered beige metal enclosure with 2 spare CUBE Bus sockets Widerange of software available to rununderFLEX macro assemblers and cross assemblers compilers and cross compilers and high level languages Supplied in 4
239. ations Following details show how to adapt a Ferguson 3845 which is the type used by most of the present Scientific Computer group and give guid ance for modifying other models Make sure that the set you choose is one with an isolated supply i e that there is no electrical connec tion between the mains and inter nal tv circuits or use an external isolation transformer The Fer guson set has a double wound mains transformer as do many portable tvs nowadays but check to make sure if you use set other than the 3845 Apart from the risk to yourself if you use a live chassis set you stand a good chance of permanently repro cessing large amounts of expen sive circuitry should something untoward occur are sy low hi nto the menory Note that sui she o it vat ot which the From the circuits in the tv set Fig 2 find where the sync signal is separated from the video the polarity of the sync signal the cathode and grid pins of the c r t socket which of the two is driven with video and the potential on the other In the case of the 3845 these points are the end of R nearest the back of the set nega tive sync pins two and one respectively the cathode and zero volts Modifications required are to break the sync signal path within the set in this case by unsoldering and lifting away the end of R and remaking the path with one half of a two pole change over switch the oth
240. ay be varied by a foot control Hirsh Jacobson Merchandising Co Ltd 91 Marylebone High Street London 1 EWW 219 PROM REMOVER New from Sweden are these i c removers which can pluck a rom from its socket without damage to the p c b orto the circuit For once the model numbers seem to make some sense 2428 is for 24 and 28 pin devices while 3640 is for 36 and 40 pins Called Prom outs they are available from Welwyn Tool Co Ltd 4 Black Fan Road Welwyn Garden City Herts AL7 1EH EWW 220 NEW PRODUCTS REEL RECORDERS Analogue sound recorders designed for audio and video production work have been manufactured by Tascam The 40 series comprises three different machines the 42 with two tracks for stereo and 7 5 or 15 in s tape speed the 44 with four tracks and the same two speeds and the 48 with eight tracks on 0 5in tape and a single speed of 15in s The machines can all use the SMPTE time codes and may be locked on to time code synchronizers and search and cue facilities are available using the real time counters The machines use ceramic capstans to improve performance and minimize wear Three heads are used and flux levels of 250nWb m or 320 may be accommodated NAB or IEC DIN equalization may be used The tape transport is heavy duty servo controlled with claimed low wow and flutter figures Optional plug ins provide synchronization with automated broadcast equipment or remote
241. ay performance The modified chroma filter will offer a better chroma bandwidth and reduced 7 8kHz twitter at the chroma transitions if it is adjusted to match the s a w filter response chroma sideband symmetry optimizec as was similarly indicated in Fig 82 When the s a w filter with the performance of Fig 96 is in use e g the SD155 the best chroma filter is the gaussian band pass filter of Fig 34 For this Fig 52 shows the amplitude response and Fig 53 the group delay per formance with Fig 52 b indicat ing the clean chroma transitions that can be obtained Mullard are expected to intro duce two new tuners later this year the U343 for potentiometer tuning and the U344 for use with a frequency synthesizer These use ELECTRONICS amp WIRELESS WORLD JULY 1984 low noise high dynamic range mosfet stages and include the first i f bandpass coupling stage and driver amplifier for the s a w fil ter The tuner i f board then need only comprise a front end tuner s a w filter and the inte grated i f amplifier demodulator TDA3541 together with a few dis crete components ref 11 Design of high grade receiver For really high quality sound and vision to feed into a comb type decode the B B C have designed a u h f tv receiver type RCI 511 being manufactured under licence by SPT Video WWW americanradiohistorv com by D C A Read B Sc Eng M I E E Fig 90 Board contains PAL modifier
242. base correctors Fig 3A Received TV picture by probe antenna Fig 3B Received TV picture by coconut tree branch TREE TV continued from page 26 the relative permitivity of water alone which is the dominant con tent of the green vegetation fol iage is around 80 at microwave frequencies In the literature low loss die lectric loaded aperture antennas and dielectric rod antennas are well known for their directional beam mode antenna radiation pattern Low loss dielectric rods have been used in practice with Teflon polystyrene 622 5 Thus after carrying indepth studies of the dielectric data cited above and the works of Zucker King Ulaby Anderson James et al weconceived ively of the idea to use the green vegetation canopy as an antenna Structure ELECTRONICS amp WIRELESS WORLD JULY 1984 We concluded that a suitably located Papaya tree of height 3 to 5 metres at 10 to 25km distance hasthe properties to pick up Band 3 tv signals from the tv tower which can be easily tapped by a suitable feeder line probe to the tv set However no attempt was made to optimize the quality of tv picture received by the organic tree antenna structure either by developing more efficient antenna probes or by adopting antenna arraying techniques In depth studies are called for to overcome the effects of hostile environments wind rain snow and to improve the s n ratio of the received
243. bitious and are seeking anew challenge these opportunities will allow you to develop your career in selling high technology products and will open up exceptional promotional paths in several different areas We can also offer an attractive salary package including company car for U K direct sales staff over five weeks annual leave staff pension and free life assurance scheme plus many other benefits associated with a major employer If you are interested please telephone Graham Addison to find out further details on Windsor 07535 63101 Or write giving ful details of career and current salary to Personnel Officer Racal Dana Instruments Ltd Duke Street Windsor Berkshire Racal s people are Racal s success 96 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com As candidate you will have degree in electronics and experience in one or more of the following Customised Chips High Density PCB assemblies CAD CAM Computer Based Systems using Pascal Assembler or BITE Proprietary Test Systems eg Gen Rad Membrain Marconi and Hewlett Packard To support the growth of the above mentioned engineering division Out This is a first class career opportunity for a person with knowledge client also has vacancies for Engineers in less Senior positions and experience of Hi Tech Electronic and Automatic Test Equipment Development Your technical nterest will be immediately
244. c orders accepted Quotations given for Large Quantities Please allow 7 days for delivery All brand new Components All valves are new and boxed Ring for iterns not listed We stock 3 000 items 9 amp 12 THE BROADWAY PRESTON ROAD 1205 0 WEMBLEY MIDDLESEX ENGLAND TBA396 0 60 Telephone 01 904 2093 amp 904 1115 6 TBAS20 0 75 Telex 932885 Sunmit CIRCLE 13 FOR FURTHER DETAILS TAG4443 0 444 TAAS SRRSSRARSASSSAGR extremely competitive price includes several sophist facilities not normally ted You can Choose frorn a range technology high reliabi amp ranging from 20 watts to 500 walts litier 15 a compact t with man ludi crophone of 60 120 requirements b Whiteley AUDIO SYSTEMS Over half a century of sound experience CIRCLE 73 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com PCBTOOLS Repair and reworking of printed circuit boards is claimed to be simple and economical with miniature power tools from Foredom Based on a motor unit and a flexible shaft drive the tools can be used to clean alter and modify boards with a variety of attachments including buffs brushes sanding discs abrasive wheels ball cutters burrs drills and saws Power is supplied by a 0 1hp electric motor through the flexible shaft at speeds from zero to 14 krev min Speed m
245. cable Remote firing also means that the triacs can be mounted next to the load which simplifies mains filtering Channels may be added by using further comparators isolators and triacs Advantage is taken of the LM339 open collector outputs to eliminate series resistors at the three phase control sections and directly discharge the ramp capacitor Transformer output should not exceed about 6V to prevent excessive dissipation in the LM339 Tim Williams Tunbridge Wells Kent ELECTRONICS amp WIRELESS WORLD JULY 1984 cES lt q ge b i gt po bh Cool and calculating Analog fast CMOS digital multipliers It takes the leader in real world overheated multifriers that are signal processing to come up with a plugged into your sockets right now family of fast digital multipliers as In addition we are proud to cool and calculating as CMOS announce our proprietary single port No more power hungry ECL NMOS 16 16 multiplier accumulator and bipolar multipliers encumbered with ADSP 1110 for new low cost designs hefty power supplies heat sinks and and 24 x 24 multiplier ADSP 1024 cooling fans for high accuracy applications No more power related design In the coming months Analog headaches reliability problems or costs Devices will be moving its entire DSP that make your temperature soar product line into a new two micron CMOS digital multipliers keep a
246. ce programmed the system may also be used connected directly to a microprocessor unit where it will function as a pseudo eprom Elan Digital Systems Ltd 16 to 20 Kelvin Way Crawley West Sussex RH10 2TS EWW 206 DECADE OSCILLATOR LEVELL ELECTRONICS have a range of oscillators cover ing frequencies from 0 02 Hz to 2 MHz There is a FUNCTION GENERATOR that provides sine 4 square triangular pulse and ramp waveforms with high a ee 2 output levels over a wide range 3 m weis are aes with 5 Qo analogue tuning and sine and square wave outputs digital tuned series are as detailed below de geh amp FREQUENCY 0 2 Hz to 1 22 MHz on four decade controls E ACCURACY x0 02 Hz below 6 Hz A 2 Pn 0 3 from 6 Hz to 100 kHz 1 from 100 kHz to 300 kHz 3 above 300 kHz SINE OUTPUT 5 V rms down to 30 pV with Rs 6000 DI DISTORTION lt 0 15 from 15 Hz to 15 kHz lt 0 5 at 1 5 Hz to 150 kHz METER SCALES 2 Expanded voltage and 21 4 dBm SIZE amp WEIGHT 260 x 180 x 180 mm 5 4 kg mms TG66B TG66A Battery Mains amp model 295 battery model 310 Prices exclude VAT Free delivery in the UK QUANTITY DISCOUNTS available We supply many other instruments including FUNCTION GENERATORS COUNTERS OSCILLOSCOPES dB amp MICROVOLTMETERS LEVELL ELECTRONICS LTD
247. ch each plus 1 p p plus V A T Barclaycard and Access taken Official orders welcome ww2 5 STATION ROAD LITTLEPORT CAMBS 6 10 60 PHONE ELY 0353 860185 CIRCLE 65 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com CASSETTE RECORDER Micro controlled cassette recorder 2 Description of cassette recorder for use with microcomputer continues with description of f s k modulator and demodulator The main criteria for choosing a suitable encoding technique for recording serial data from the output of microcomputer RS232 or t t 1 levels are in my opinion reliability circuit sim plicity and perhaps most import antly the ability to be used with any good set of recording play back electronics The microcom puter user is primarily concerned with reliability and ease of use of any encoding technique He is not interested in very high speed techniques if half the time the data is recorded or played back incorrectly or if the tape recor der settings need constant adjustment There have been a number of designs in various electronic magazines for high speed recording techniques The fastest of these of which lam aware was for 4800 baud I also have had some experience of designing suitable encoding techniques for high speed serial data recording and am therefore very aware of the problems Readers may recall the series of articles in this mag
248. ch plugs into one of the computer s joystick ports This software key as Microdeal call it must be in place to enable the cassette to load properly The company hopes the device will put an end to unauthoried tape to tape copying since without it the cassette is useless And Microdeal believe that copying the module itself would call for resources beyond those of the home user The key or dongle was developed to Microdeal s specification by Northern Software Consultants of Newcastle upon Tyne It costs about 2 and can be applied to cassette or disc programs for almost any microcomputer For business computers a version can be made to interface with an RS232 port different key is required for each title WWW americanradiohistorv com Microdeal will be adding the key to several new programs on their Tom Mix Software label They hope to discover whether increased sales to frustrated pirates will outweigh those lost to schoolchildren who might otherwise have bought the game by pooling their pocket money Also fitting in to the RS232 port of a computer is the Sesame security key from Polytech Engineering Services Ltd Without inhibiting the use of the port any software used with the Cell news Trials for Racal s cellular radio telephone system to be known as Vodafone to start in December 1984 ahead ofthe original schedule over a 150 square mile area of London The service wil
249. co founder of Ambit International recently sold to Bulgin told E amp WW Amstrad has increased reliability of its products over the years and will continue doing so We expect a 2 or 3 return rate the biggest problem will probably be with people who haven t read the instructions properly and those who spill tea in the cassette mechanism Main i cs used are the 6845 c r t controller for 80 column text and up to 640 by 200 picture elements an 8912 three channel sound generator and an 8255 parallel i o device Screen memory is 16K Thereisa Centronics parallel printer output andan expansion port but regrettably the connectors the edge of the p c b and not gold plated The keyboard and its separate numeric and cursor control pad is full size and uses familiar keytops but has a membrane switch matrix underneath to keep costs down Matsushita membrane technology is used conductive rubber against gold plated p c b contact areas 50 theoretically at least it should last a long time Considering that the average consumer is now wary of microcomputer manufacturers who promote products using predictions made by design engineers Amstrad would be risking too much to promise all this but to present only part of it especially when one takes into account Britain s current aggressive home microcomputer market Delays inthe introduction date could be devastating The company expects to produce 200 000 units
250. coder and it provides a few kbit s spare data capacity for supplementary pur poses Choice of modulation techniques The choice of a modulation tech nique for any digital transmission system results from a compro mise between the required band width the signal to noise ratio required to achieve an acceptably low received bit error rate this gt Receiving demodulating and measuring equipment inside BBC survey vehicle ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com by Hartwell BBC Research Department Ted Hartwell joined the BBC in 1963 after serving four years as a design and development engineerin industry Most of his time in the BBC has been spent in the studio engineering department at the Television Centre in West London where he worked as an engineer and more recently as a technical writer He became Research Author at the BBC s Research Department last year Table 1 Proposed baseband coding for experimental digital stereo sound with terrestrial television Audio bandwidth 15kHz Pre emphasis CCITT Audio sampling rate 32kHz Samples per block 32 Audio coding 14 10 bit near in stantane ous comm panding 640kbit s Scale factor bits 3 per block per Chan nel 6kbit s Error protection 32kbit s for sample words Error protection for 4kbit s scale factor bits Framing 8kbit s Available
251. coo CMOS process This process enables head whether your application calls for the cycle times for all parts to improve digital filters FFTs matrix operations roughly a factor of 2 5 to one For acceleration example we will be offering a 16 x 16 DIPs flatpacks LCCs and space multiplier with a 60nS multiply time saving pin grid arrays our improved a low power CMOS technology second source products offer addition to major speed break throughs comparable speed at less than 1 20th on industry standard parts watch for the power All at competitive prices us to announce a broad line of they ll replace the proprietary DSP devices during 1984 POWER SPEED nS PART DESCRIPTION REPLACES SSC AME CAN ANE M Te ADSP 1080 8x 8 MULTIPLIER MPY 08HJ 0 09 85 100 115 ADSP 1008 8x 8 MULT ACC TOC 1008J 0 1 105 120 140 ADSP 1081 8x 8UNSIGNED MULT MPY 8HUJ 0 1 75 90 105 ADSP 1012 12x 12 MULTIPLIER MPY 12HJ 0 15 110 130 150 ADSP 1009 12x 12 MULT ACC TDC1009J 0 15 130 155 180 ADSP 1016 16 16 MULTIPLIER MPY 16HJ 0 15 145 170 200 ADSP 1010 16 16 MULT ACC TDC 1010J 0 15 165 190 220 ADSP 1110 16x 16 SINGLE PORT MAC PROPRIETARY 165 190 220 ADSP 1024 24 x 24 MULTIPLIER PROPRIETARY 200 235 275 Contemporary ECL and Bipolar parts are spec d for a maximum CASE temperature of 1 25 C Due to their high dissipation
252. creen terminal By touching squares on the screen operators can answer incoming calls call up background information make internal and external calls all regular numbers are stored and dialled automatically and send or receive telexes The link from Gatwick to Birmingham was for two ofthe 12 terminals in use at Gatwick Another communications system installed by BT at Gatwick is for the air traffic controllers Through ADEKS Advanced Design Electronic Key System allows controllers to get in instant touch with other controllers and with telephone lines Mike Morris a director of BT National Networks expressed his pleasure at receiving the order from the Civil Aviation Authority He hoped that similar organizations in other countries would follow suit Expanding American teletext National Association of Broadcasters has joined the FCC in its proposals to authorise American tv stations to provide paging and a variety of data transmission services in the tv signal vertical blanking interval The services should include video games and computer programs and other interactive services The decision to provide these services should be left to the market place In its submission the NAB said that the system was technically sound promoted competition and conductive to spectrum efficiency It also said that the services should not be subject to common carrier regulation Cable services which are obliged to
253. d communications equipment Advanced field Croydon 3 Technical Support Engineer 11 000 car Design test and service of office automation systems Overseas travel Berks 4 Test Engineer Test and troubleshoot minis and micros Berks area Service Engineer 10 000 car Computerized info data retrieval systems Training in U S A Middx area Hundreds of other Electronic and Computer vacancies to 12 500 Phone or write Roger Howard C Eng M I E E M LE R E CLIVEDEN CONSULTANTS 92 The Broadway Bracknell Berkshire Tel 0344 489489 1640 CLIVEDEN Outstanding opportunities to move into Sales or Sales Management U K amp Export The expansion in our markets means that we urgently need to recruit the following staff for key positions in the U K and overseas SALES ENGINEERS TECHNICAL SUPPORT ENGINEERS AREA SALES MANAGERS REGIONAL SALES MANAGERS We are Racal Dana Instruments Ltd an international manufacturer of sophisticated electronic test and measurement instrumentation for the radio communications ATE and microprocessor based industries We are looking for men or women educated to at least HNC level in electronics who have a solid basis of practical experience Knowledge of the radio communications industry would be advantageous and for overseas sales a second language French or Spanish would be useful If you are am
254. d by Parliament and operational responsibility for this service will be transferred from British Telecom to DTI The Act abolishes the advisory committee of the 1949 Act and strengthens the powers of the licensing authority number of ways including the ability at any time to revoke or vary the terms of any broadcasting or communications licence in the interests of ELECTRONICS amp WIRELESS WORLD JULY 1984 COMMUNICATIONS COMMENTARY national security or relations with the government of a country or territory outside the UK Sending of false or misleading messages becomes an indictable offence DTI have the right to prescribe technical requirements for services It remains to be seen how strictly the Courts will interpret the amended Wireless Telegraphy Acts and the effort that will be put into enforcing them On the face of it it would seem to be an instrument capable of quickly putting off air the broadcasting pirates and the more numerous pseudo amateurs such as the International C B around 6 6MHz Less easy to suppress will be the unlicensed amateurs and c b operators who may still find it possible to pass unnoticed for a time by operating in accordance with the licences they have omitted to obtain It seems likely that con cessions will be made soon to small time broadcasters by the introduction of some form of community radio or special event radio licence involving for ex
255. d keyboard with 67 quality GOLD normally open switches on shops etc Supplied in a used but working GREEN switch for high det text standard X Y matrix Complete with 3 LED indicators amp i o cable ideal micro Condition applications and matching BBC colour conversions etc pcb DIM 15 x 5 24 95 Carriage on keyboards 3 00 ONLY 55 00 PLUS 9 50 CARR 6 INS scheme make this monitor ideal for the most exacting user Brand new and Fully Guaranteed only 199 00 10 00 carr 2 SEMICONDUCTOR DERE NO SUPER STERU SOON D aa Mixed Semis amazing value contents Join the communications revolution with our RAN 4 22 include transistors digital linear triacs range of EX TELECOM data modems Made to Made to the very highest diodes bridge recs etc etc All devices most stringent spec designed to operate spec the TEC Starwriter 2 TTL grab bags at a price which two up to 300 baud full duplex ANSWER or CALL Processor electronics MODEM 20 1 Compact unit for use with Supplied absoiutly BRAND NEW with 90 day guarantee and FREE daisy wheel internal transformer isolated regulated DC supply all components mounted on two fibre glass PCB boards which hinge out for ease of service many internal controls for linearity etc The monitor accepts standard Call for Details Post 4 Packing on all fans 1 6
256. d to total of Goods and Carriage STEWART OF READING M 110 WYKEHAM ROAD READING BERKS RG6 1 1 Telephone 0734 68041 Callers welcome 9 a m to 5 30 p m Monday to Saturday inclusive CIRCLE 22 FOR FURTHER DETAILS 42 The Microvalue Group dealers shown below represent part of the Gemini network For expert advice and full details on the Gemini System contact your nearest dealer today AMERSHAM COMPUTER CENTRE LTD 18 Woodside Road Amersham Bucks HP7 Tel 02403 22307 Telex 837788 BUSINESS amp LEISURE LTD 16 The Square Kenilworth Warwickshire CV8 1ED Tel 0926 512127 CENTIFLEX MICROSYSTEMS LTD Unit 6 Perry Road Staple Tye Harlow Essex CM18 7NW Tel 0279 442233 ELECTROVALUE LTD 28 St Judes Road Englefield Green Egham Surrey TW20 Tel 07843 3603 Telex 264475 E V COMPUTING 700 Burnage Lane Manchester M19 NA Tel 061 431 4866 HENRYS RADIO 404 Edgware Road London W2 Tel 01 402 6822 LEEDS COMPUTER CENTRE 55 Wade Lane Merrion Centre Leeds 152 8NG Tel 0532 458877 OFF RECORDS LTD Computer House 58 Battersea Rise Clapham Junction London SW11 1HH Tel 01 223 7730 PARKSTONE ELECTRONICS LTD 18 Station Road Lower Parkstone Poole Dorset BH14 8UB Tei 0202 746555 SKYTRONICS LTD 357 Derby Road Nottingham NG7 2DZ Tel 0602 781742 TARGET ELECTRONICS LTD 16 Cherry Lane Bristol 51 3BG Tel 0272 421196 NEWBURN ELECTRONICS LTD 58 Manse Road B
257. ddressed and the data on the bus lines being different from that planned by the v d u controller The result is speckling on the screen which particularly during scrolling can almost obli terate the wanted information Common solutions to this are to force the video output to the black state during c p u accesses or to only allow access ELECTRONICS amp WIRELESS WORLD JULY 1984 to the v d u during flyback ods i e when the video is nat urally suppressed Unless done sere selective blacking can ly noticeably reduce display intens ity the second solution reduces the rate at which characters can be passed to the screen Terminal type or i o mapped v d us appear to the c p u as input output channels so their advantage is in not occupying any system memory Their disadvan tage is in circuit complexity Cir cuits must be provided for receiv ing and interpreting commands as well as data For example the i o mapped v d u must recog nize a request for the character at a particular screen location in cluding transfer of the screen coordinates information im in access or the need to clear the rest of the current display line and return the cursor or next screen location pointer to the left hand margin on receiving the carriage return control character 15 common practice to pass data to WWW americanraciohistorv com memory mapped by J H Adams John Adams
258. directional running I think by the way that Mr Hill is wrong to state the rotor is not a permanent magnet You can feel the holding force if you turn this hf noise stopper ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com qme by finger and thumb and generate about 50 volts or so in one winding by running it as a dynamo Also I have some motors from the States including a Rapid Syn with four coils which has a magnetic hold so strong that itis hard to turn by hand This performs very well as it has 12 volt coils and better torque than the Slo Syn Despite this one seeming error the article is most interesting as I have made up a plotter in the past using ordinary motors and a potentiometer balance circuit to do transistor curve tracing It was not very good and needed to be refined so it was scrapped Your write up leaves out some important details for me since it would be nice to make up a stepper plotter controlled by Basic and digital to analogue output from the computer with a potentiometer to compare positions The ball bearing idea 1s a good simple I have used system of crossed ball races with silver steel rods and this has proved quite good See sketch A further article dealing in much more detail with the electronics of the plotter would be welcome to me and I suspect many others A J Quinton Thorpe Bay Essex TECHNOCRATIC BONDAGE Yo
259. e each emitter is embedded in its own individual medium 8 All radiating media have similar characteristics and as a corollary exist within or throughout each other and have a general propagational velocity of c where remote from matter 9 The characteristics of media in 8 may be modified in the proximity of considerable conglomerates of dense matter Proposition 7 was onginally stated by Michael Faraday Phil Mag Vol 28 No 188 May 1846 and as misinterpreted by Clerk Maxwell to have the meaning of 5 and thus taken as providing the basis for his equations of the electromagnetic field When 5 appeared to have been rendered untenable by some rather inept exercises in research Einstein raised his 1905 paper in an attempt to show that we can have as many ethers as we like he made the mistake of implying that all receivers of radiation must be embedded in their own individual ethers this being the interpretation he gave of 2 Faraday s proposition 7 amounts to the complement of this and avoids the complication of 2 Although 1 may be invalid if the physical universe has a centre point about which it is in rotation and 2 cannot be tested unless its ambiguity is resolved 3 5 7 8 and 9 can be subjected to physical investigation to varying degrees of determination It is doubtful that the members of professional bodies are as yet prepared to embark on such work since it wou
260. e full IEEE 488 standard includes the capability to pass control to another controller connected to the same bus Most GPIB controllers commercially available include this capability typically as a high level language statement Also several commercial 1 5 1 devices are available which implement this GPIB feature As recently as February 1984 your magazine described an interface module available for the BBC microcomputer using 1 6 1 device which includes bus control transfer More than one controller may have access to peripherals a single GPIB through the existing standard using software It is not necessary to spend time designing a hardware multiplexer for GPIB controllers The user who finds that he needs to attach several controllers to his bus will find a neater and quicker solution by selecting his bus controllers with this capability built in There are several well known international manufacturers of GPIB instrumention and several less well known national ones who can supply GPIB controllers with pass control as a standard feature J Summers Application Manager Fairchild Camera and Instrument UK Ltd IS LIGHT VELOCITY A CONSTANT The questions about relativity theory will not go away Michael M Albahari Is light velocity a constant February letters is mistaken if he considers that the issue could be resolved by accurate measurement of time and distance the real conflict is betw
261. e higher so they should stand in the ratio of 1 1 5 In practice the Two digit rule will prevent this from always being met and rounding of a calculated value will be required This must always be in the sense to close the gap between the two values since the other way will produce a hole into which components could fall and so be lost This consideration also leads to the conclusion that when rounding has taken place the next value must be based on that rounded value and not the calculated one This destroys once and for all any elegant arithmetic relation Lastly in order to keep the total number of values down as far as possible it is sensible to select the 1096 values from those already existing in the 596 range if possible and the 2096 from the 10 We can now see where this reasoning gets us Starting initially from the lowest value previous selected value selected x1 5 value 1 1 5 1 5 2 25 2 2 3 3 3 3 4 75 4 7 Now the problem On this basis the next value should be 7 0 although it could be less and the next is over 10 by quite a bit Let us therefore consider what happens if we calculate back from 74 FEEDBACK 10 We will now have a value 6 7 although it could be more So there are four possible values available all of which would meet the holes criterion 6 8 is the only one to appear in the 5 range orin the 10 range for that matter Mr Scott tells my namesake
262. e portable recorders are carried whilst recording inertial effects can cause timing shifts of several lines The drum attempts ELECTRONICS amp WIRELESS WORLD JULY 1984 to rotate at constant speed with respect to the earth owing to its inertia and if the v t r is turned about the drum axis the drum phase will change until the drum Servo can correct it This is often erroneously referred to as gyros copic error Video tape is also subject to dropout where the playback r f level is too low to resolve the fre quency Although the mechanism of dropout cannot in itself change H sync Normal cycle Burst swing lag i cycle Burst Swing lead a Inverted lt cycle Burst swing lag gs cycle Burst swing lead WWW americanracdiohistorv com by J R Watkinson M Sc B Sc Fig 10 In PAL subcarrier must be at odd multiple of one quarter line rate for U and V spectral peaks to interleave with luminance Y Unlike NTSC there is no dominant component at 1 2f points Fig 11 Quarter cycle H burst swing combine to give four line sequence normal and inverted pairs which is not absolutely defined One cycle of burst 6 5 approx cycle sc lead change VY cycle sc lead 180 change 72 V cycle sclead change cycle sc lead 180 change 1 28
263. e self diagnostic testing routines built in for fault findings As a trump card Thorn EMI are hasty to point out that the system is compatible with the IBM PC and expect to find a large market for the device amongst micro users Thorn EMI Datatech Ltd The Mill Wookey Hole Wells Somerset BA5 1BB EWW 210 NUJ Reed International dispute This space is one result of the continuing dispute between members of the National Union of Journalists and Reed International subsidiaries Business Press International Butterworths Hamlyn Books and IPC Magazines ADAPTIVEH F RADIO A radio system which improves frequency management for communication networks that have several transceivers is announced by Racal Messenger The VRM4550FS combines frequency scanning receiver with a selective call transmitter It monitors up to ten pre selected frequency channels locks automatically onto a received signal and decides if it is the station being addressed before warning the operator of an incoming message This facility enables the optimum receiver frequency to be selected from the ten pre programmed channels by the transmitter station taking into account the existing h f propagation conditions Sets of the transceivers can have a different selection of channel frequencies so that networks can interlace or overlap while being secure from each other With a transmitting power of 100 or 120W the synthesized frequency tran
264. ea SA5 514 EWW 207 NEW PRODUCTS SATELLITE WEATHER MAPS The use of new circuitry anda study of users requirements has enabled Feedback to produce a weather satellite system the WSR513 at a fraction of the cost of similar systems The basic version will receive the APT automatic picture transmission signals from orbiting satellites in the 136 to 138MHz band The addition of extra modules and a parabolic dish antenna allows reception of S band transmission from geosynchronous satellites in the 1690 to 1697MHz band basic version is supplied with a helical omnidirectional antenna which incorporates a single stage preamplifier This feeds a tuneable v h f receiver and the a m subcarrier from this is output to a decoder which converts it to digital form which is entered into the internal memory and provides a synchronizing signal The memory is continuously scanned by the raster timing generator and images are converted back to analogue signals and displayed onthe screen Front panel control allows the selection of resolution and format and local or satellite time for scan resolution and this can retain or remove the Doppler effect caused by satellite motion The version to receive S band transmissions includes alow noise preamplifier in the dish antenna The signal from this goes through an r f switch which is used to select S band or APT transmissions Controls include channel selection auto
265. ection to Netway local networks The full capacity of the system is a large multi node network incorporating up to 254 Netway processors each having a combination of up to 32 workstations and host ports though the system can start by serving just one or a few workstations Scicon Ltd 49 Berners Street London W1P 4AQ EWW 209 87 HARD DISK DRIVES HOT LINE DATA BASE Fully refurbished DIABLO DRE series 30 2 5 Mb disk drives DEC RKOS NOVA TEXAS compatible Front load Free stand or rack mount 530 00 type lid removal 8295 00 me3029 PSU unit for 2 drives 125 00 THE ORIGINAL FREE OF CHARGE dial up data base DIABLO DRE 44 4000A B 5 5 ex stock from 995 00 B 10005 of stock items and one off bargains 10005 of spares for 530 4000 3200 ex stock ONLINE NOW 300 baud full duplex CCITT tones 8 bit Plus in house repair refurbishing service Call tor details or ordre 0 1 6 79 1332 unit is duis an removable top lid filtering trip Switc ower un EX STOCK INTEGRATED CIR LEDs mounted on Ali front panel rear cable entries etc etc Units are in good but used condition Supplied for D8085AH 2 D8086 D8257 5 240v operation complete with full circuit and tech man one quality computer cabinet with integral switched mode PSU Mains filtering and twin fan cooling Originally made for the famous DEC PDP8 comput
266. ed TSC3660 Repeater Gain 16 36dB UHF 10 3048 VHF Maximum output 60dBmV TCUV AsTCUU except UHF to VHF converter Quote Channels required TSC3665 Repeater Gain 16 36dB 10 3048 Maximum output 65dBmV TCVU As TCUU except VHF to UHF converter Quote Channels required TSC3060 Repeater Gain 10 3048 VHF Maximum output 60dBmV QUALITY AT LOW COST TAYLOR BROS OLDHAM LTD LEE STREET OLDHAM TEL 061 652 3221 TELEX 669911 _ CIRCLE 72 FOR FURTHER DETAILS SPECIFICATION 1015 ANALOGUE DC Voltage 0 25 2 5 25 250 SPECIFICATION 6010 DIGITAL 5 10 Amp AC DC i e s rs 10 50 250 1 x 170 x 89 x 38mm 50 d po EUM eight 400g inc battery 0 to 1 MegOhm in 3 amp Current 200uA to 10 gt 3 ar os oltage mV to i Resistance 2000 1020 0 ARMON ELECTRONICS LTD Siz2 amp Weight 105 x 63 x k input impedance 1 x olay Digit 13mm LCD Heron House 109 Wembley Hill Road 19 RANGES COMPLETE WITH O load Protection ranges Wembley Middlesex 8AG BATTERY AND TEST LEADS Accuracy 0 5 DC Volts Telephone 01 902 4321 3 lines TELEX No 923985 28 RANGES EACH WITH FULL Please add 15 to your order for VAT P amp P free of charge Payment by cheque ES OVERLOAD
267. edition is available now from the RSGB sales counter price 5 89 or by post price 7 14 THE MICROWAVE NEWSLETTER TECHNICAL COLLECTION Compiled by J N Gannaway G3YGF S J Davies G4KNZ This new book comprises a collection of technical material published in the Microwave Newsletter from April 1980 to May 1983 The material is copied directly from typewritten originals and is 3GHz compiled in sections covering 1 2 3GHz 3 4GHz 5 7GHz 10GHz general narrowband 24GHz Millimetric Bands Oscillator Filter Design Antennas Calculating Bearings Radiation Hazards Test Equipment Size 4 140 pages Price 6 00 from RSGB sales counter or 6 83 including P amp P OTHER RSGB PUBLICATIONS A Guide to Amateur Radio 19th edn Amateur Radio Awards 2nd edn Amateur Radio Operating Manual 2nd edn HF Antennas for All Locations Radio Amateurs Examination Manual TOth edn Radio Communication Handbook paperback Teleprinter Handbook 2nd edn Television Interference Manual 2nd edn VHF UHF Manual 4th edn The RSGB is the national society representing all UK radio amateurs Membership is open to all interested in the hobby including listeners The Society publishes a range of books log books and maps for the radio ama teur A large selection of other radio and electronics books are also stocked a full list is available on request Contact the membership ser vices section for more informati
268. een incompatible philosophical hypotheses The complex of notions embodied into the Special Theory of Relativity and from which the General Theory was developed by processes of logic is based on two propositions selected from several alternatives 1 All inertial frames of reference are equivalent in their physical characteristics 2 Light travels in any fixed direction with the same velocity c in all inertial reference systems Professor Albert Einstein stated 2 as a corollary to 1 in his 1905 paper Electrodynamics of Moving Bodies but notwithstanding the validity of 1 it is impossible to give unambiguous interpretation of 2 because velocity exists between two physical entities andis not something that resides independently within frames of reference Implicit in the theory as developed from 1 and 2 are two generally unstated propositions 3 Electromagnet radiations impinge upon the surfaces of all materials conglomorates from unoccupied space with the same velocity c 4 Unoccupied space has no characteristic which regulates the propagation of radiations crossing it except to guide it in a straight path To render 3 and 4 some appearance of plausibility Einstein made the suggestion that The relations between co ordinates of two systems in uniform motion relative to each other cannot be indentical with those of Newtonian physics in which simultaneity is absolute The prob
269. elf system offers every facility imaginable to the home constructor Just look at program in monitor board Floppy disc controller for two 5 25 inch 40 or 80 track 64K main system ram 128K alpha graphic simulated drives disc ram Battery backed realtime clock calendar Alpha display of 108 colums by 24 rows of 128 columns by Battery backed ram for storing system startup parameters 72 rows Two serial RS232 1 0 ports 50 19200 baud under software True high resolution graphics with 768 x 576 resolution control High speed hardware vector generation using NEC 7220 Centronics compatible printer output port graphics controller Point line rectangle circle arc and Parallel keyboard input port area fill facilities Composite video and separate video sync outputs High speed ram disc for fast data access Buffered expansion buss for user added enhancements Up to 256K silicon disc eprom on plug in eprom carrier Auto configuring FLEX disc operating system boot 12x9 5in through hole plated main PCB 3x4in eprom FLEX which is supported by MICROBOX is a well proven industry standard disc operating system with a wealth of available software packages Basic Forth Pascal PL9 and C high level languages as well as assemblers word processors and electronic spreadsheet are currently available Clever programming techniques have permitted the inclusion in the system monitor of a boot program that aut
270. en compared to any ways Plug tacle Conn 1 end 145p 165p 240p 350p Solder Grey meter currently available similar programmer In addition to normal 16 Ped iria 1208 2 210p 230p 345 540 36 way plug Centronics eprom programming now able to load your favourite 268 175b 150p 2405 24 Ribbon Cable with Sockets 25 25 25125 1500 basic programs onto eprom E 200p 160 320p 20 pin 26 34 pin 40 36 way socket Centronics 20 way 85b Menu Driven Software provides user friendly options 40 220p 190p 340p 1end 160p 200p 280p 300p 5 50 5 50 26 way 120p for programming the eprom with 50 235 200p 3900 2ends 290p 370p 480p 525p 24 way plug IEEE 5 00 4 75 34 way 160p a Basic programs 24 socket IEEE 5 00 4 75 40 way 180p b Ram resident programs D CONNECTORS Ribbon Cable with D Conn Mtg Skt Ang pin 30 way 200p c Any other program No ot ways 25 way Maie 500p Femaie 550p 24 way 6 00 36 way 6 50 Y Programmer read blank check program verity at MALE 55 37 any address addresses the Eprom Solder 80 105p 160p 2500 RS 232 JUMPERS URO EDGE wee selection is simplified by a single rotary Angled 150p 210p 250p 365p 25 way 0 CONNECTORS CONNECTO RS FEMALE ji T 24 Single end 5 00 DIN 41617 Plug 01 0 156 Programming voltage selector switch Solder 105p 160p 200p 335p 4 Singl Femal 525 vas Full Editor with ASC
271. ence and ability and be able to mend a much needed analogue recorder yet tomorrow have the ability and enthusiasm to switch your attention to helping out a scientist with his her broken computer controlled spectrometer Aged around 30 you should have a qualification in Electronics or Instrument Maintenance such as the City and Guilds Full Technical Certificate together with 5 to 10 years experience servicing electronic equipment knowledge of modem electronic instruments and their can struction and an understanding of the electronics interface with computers is essential We offer a competitive salary depending on experience and ability Excellent benefits include five weeks holiday pension and life assurance scheme and generous assistance with reloca tion expenses as appropriate Please write enclosing a full CV and quoting ref WRL 276 to A Murdoch Personnel Officer The Wellcome research Laboratories Beckenham Kent BR3 3BS 2613 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com Wellcome 101 Classi ed ICLES FOR OPTOELECTRONICS DATA BOOK 1984 by Texas 6 00 DIGITAL ELECTRONIC CIRCUITS amp SYSTEMS by N M Morris PRICE 5 45 MICROELECTRONICS A PRACTICAL INTRODUCTION by R A Sparkes PRICE 8 50 SOLDERING IN ELECTRONICS by R J Klein Wassin Wassink PRICE 51 00 Price OPTICAL FIBER COMMUNICATIONS BY Keiser PRICE 9 50 DIGIT
272. entral London location Padding ton Phone write NOEL KEYWOOD 64 Castellain Road Maida Vale London W9 1bX 01 289 3533 PCB HAND ASSEMBLY any quantity Highest quality at sensible prices INTER ESTED Phone 01 274 3070 2570 QUARTZ CRYSTALS OSCILLATORS AND FILTERS of types Large stocks of standard items Specials supplied to order Personal and orders welcomed SAE for lists please OEM support thru design advice prototype quantities production schedules Colledge Electronics Mernott Somerset TA16 5NS Tel 0460 73718 2612 e Crystal 2764 EPROM250NS 5 65 FD1771 Foc 17 50 75p P amp P VAT PREMIER MICROSYSTEMS LTD 208 CROYDON RD LONDON SE207YX 01 659 7131 MALDEN SURREY 2538 7838 Anytime ACCURATE w SS RELIABLE 2 enguities send in stamps for brochure QUARTZ CRYSTAL CO LTD Q C C WORKS WELLINGTON CRESCENT 01 942 0334 amp 2985 8493 SHEETMETAL FOLDERS 18 x 18G Vice or Bench model 38 Leaflet 01 890 2569 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com ARTICLES FOR SALE COMMUNICATION RECEIVERS RACAL SOOKC S TO 30MC S IN 30 BANDS 1 5 WIDE RA17 125 RA17L 150 RATI7E 225 NEW METAL LOUVRED CASES FOR ABOVE 25 ALL RECEIVERS ARE AIR TESTED AND CALIBRATED IN OUR WORKSHOP SUP PLIEO WITH DUST COVER OPERATION INSTRUCTIONS CIRC
273. er system costing thousands of pounds Made to run 24 hours per day the PSU is fully screened and will deliver a massive 5v OC at 17 amps 15v DC at 1 amp and 15v 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 7415112 7415373 SD5AAs ico enden by 2 81 news ietter 49 95 19 wide 16 deep 10 5 high i size up to 1000 watt load Useable area 16 w 10 5 h 1 7407 2102 6 4116 3 2127 compact completely cased unit with 3 pin fitted Also available LESS PSU with FANS etc Internal dim CALL SALES OFFICE FOR PFICES COOLING Keep your hot parts COOL and RELIABLE with our range of BRAND NEW professional lt cooling fans 99XUOI Dim 92 x 92 x 25 mm N Miniature 240 v equipment fan complete with finger guard 9 95 GOULD JB 3AR Dim 3 x 3 x 2 5 compact very quiet running 240 v operation NEW 6 9 BUHLER 69 11 22 8 16 v DC micro socket Up to 750 watts 9 99 19 w 16 d 10 5 h 19 95 Carriage amp insurance 9 50 5 CASED Superb little unit made by HITACH in ergonimcally designed free standing case Very high definition will displa small but readable 132 columns wide 12v D CENTRONICS 739 2 opp 800 so ideal for mobile NE The Do Everything Printer at a price that will Supplied in AS NEW Condition
274. er This makes the circuit capable of being used with a much wider range of cassette deck recorder playback electron ics overcoming some of the problems associated with the high frequency pre emphasis cir cuitry The triangle to sine wave converter is also a variation of a circuit to be found in the Signetics book It is possible to adjust the sine wave total harmonic distor tion to less than 1 by setting the amplitude of the triangular wave form correctly Phase detector Demod d Ref d 15V RS232 type o p ttl 15V The heart of the f s k modu lator Fig 5 is the voltage con trolled oscillator i c the 566 These i cs are designed to oper ate with a nominal voltage on their modulation input pin 5 8 below the positive supply rail i e 7 8 A modulation of this vol tage by 10 produces a modula tion of the frequency output by the same amount For a V of 15V V 8 is 1 875V Plus and minus 10 of this value gives vol tages of approximately 1 69 and 2 06V below the positive supply rail i e actual voltages on pin 5 of 13 31 and 12 94V the 1 5kQ and 12kQ resistors produce nominal voltage on pin 5 of 13 33V When the transistor is conducting the 39kQ resistor is effectively in parallel with the 12kQ reducing the effective resistance to about 9 2kohms The voltage on pin 5 when the transistor is conducting is thus reduced to
275. er input of which is a combina tion of the two sync signals The other half of the switch 15 used to connect a decoupling capacitor to the 74 585 4 bit comparator produces a signal on and low respective an tO and the menory appears 5 is able iva gt a arn Further decoding is necessary though to ensure tha this ber oe c Peg e AA Mil access several things It switches the that they feed bus address lines into the memory to the menory and 68455 This last point is necessa a 4 6MHz 280 processor Maximum 64K byte ram 58K byte ram available using SciDOS Display Up to 32 lines of 96 characters full 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 drives may be used either single or double dens 85232 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 asynch ronous 5 to 8 bit with 1 1 5 or 2 stop bits RTS and CTR signals conrol serial data flow Eight bit parallel data input is buf fered by schmitt i cs Eight bit par allel output drives five 1 1 1 loads The mos i o lins operate event counters
276. er with the cutters we were extremely impressed Naturally we also tested them with wire and were equally pleased with the results We decided to offer readers the alternative of a set of the three most vital tools comprising top cutters side cutters and snipe nose pliers smooth inside jaws are approximately 434 long In shops this set Set A would compras cost about 29 70 but our price to readers is 19 50 incl VAT and UK p amp p s SACS Our alternative choice is the above set plus a pair of round nose pliers which Nose Pliers are extremely useful for shaping wires etc This set Set B comprising the four tools would normally cost 38 but we are offering it at only 24 75 incl TOP CUTTERS VAT and UK p amp p flush cutting We regret the tools are not available separately only the sets as offered SIDE CUTTERS To order either of the use coupon or photocopy or on plain paper and send with crossed cheque PO made out to Wireless World Offers Send to Pliers Offer 48 Beauchamp Place London SW3 1NX Allow up to 28 days for delivery UK addresses only Closing date July 31st 1984 VAT receipt will be supplied if SAE is enclosed with order Coupon to Wireless World Pliers Offer 48 Beauchamp Place London SW3 1NX Please send me Pliers Cutters Sets NAME please print Set A at 19 50 ADDRESS Set B at 24 75 for which enclose total SNIP
277. erface 1 Dual Floppy Disk Drive iai MSAN net LA36 Console 3 500 Ww u TERMINALS VT100 VDU TERMINALS LOW COST VOUS The world s best selling VDU Dont make Two of the most do with a look alike buy the popular all purpose genuine article at only 695 VOUs on the market Range of options available i e HAZELTINE 4500 VT XXAA 20mA 112 E cH VTIXXAB Advanced 325 Video 75 NEWBURY VTIXXAC Printer 7009 325 LA36 DECwriter KSR TERMINALS SPECIAL PURCHASE DAISY WHEEL purehase al moet popu IA HYTYP 11 Cps terminal providing Column pu A e dde quality upper lower case printing Tractor feed printer with microprocessor control and integral stand and solid die cast aluminium frame CHOICE Receive only bidirectional model with 12 bit parallel 295 n input and with 20mA variable 10 12 325 pitch printing with EIA RS232 OUR SPECIAL PRICE ONLY Also available Recerve only 395 version model inclusive of integral desk LAS price unit 250 and 275 respectively A copy of our trading Conditions be 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 uc zw zi 2 49 FOR FURTHER DE E CIRCLE 49 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 Electronic Brokers 8
278. ericanracdiohistorv com HAND HELD TERMINALS TESTERS A number of hand held terminals may also be used as support devices for communications equipment Such devices made by G R Electronics have been used to test p a b xs multiplexers and other processor based systems for commissioning and installation of such systems in the field The 14B for example has a 14 digit display 92 character memory and RS232 and or 20mA loop interfaces as standard Options include a rechargeable battery pack making it completely independent of outside power sources and RS422 432 interface for longer cable signals Larger memories and more facilities are offered by the 42B and 42C terminals which have 40 character displays battery operation with memory protection signalling up to 9600 baud and from 8K to 64K of ram Different protocols are optional and the units can store diagnostic routines for on site testing and can capture data for later analysis The company also offers an acoustic coupler and a data recorder to complete a battery operated system for the collection and transmission of data G R Electronics Ltd Fairoak House Church Road Newport Gwent NPT EWW 215 FIBRE OPTICMODEM High data rates low transmission line costs and freedom from electromagnetic interference are three of the several benefits claimed for Easydata s Raycom 2000 fibre optic modem A dual RS232 interface allows two separate pe
279. erify and other utilities e One vears tull guarantee provided e lotally compauble with 5 drives e Direct Drive TECHNICAL PERFORMANCE Single Density Double Density Capacit 250K Bytes S00K Bytes Recording density 4 915 BPI 9 830 Track density 100 TP 100 TPI number of tracks 40 each side 40 each side Recording method PM Rotational speed 300 RPM 300 RPM Transfer rate 125K Bits Sec 250K Bits Sec Access time track to track 3 ms 3115 Access time seuling 20 ms 20 ms Motor start time 0 5 sec 0 5 The Opus Super 3 Microdrive is now available from W H Smiths and leading specialist shops Dual disc drives are also available lor 460 OPUS SUPPLIES LTD 158 Camberwell Road London SE5 OEE Opening hours 9 00 6 00 Monday Friday CAD 01 701 8668 9 00 1 30p m Saturday SZ 01 703 6155 fo Opus Supplies Lid 158 Camberwell Road London SES ORE Please rush me the following ALL PRICES INCLUDE VAT amp CARRIAGE THE OPUS _ a SUPER 3 Lenclose acheque Or please debit my credit cardaccount with the amount Mv Access Barclayeard please tick M FOR USE WITH YOUR MICRO CIRCLE 33 FOR FURTHER DETAILS Telephone Opus us M ESTABLISHED 30 YEARS U K RETURN OF POST ORDER SERVICE ALSO WORLDWIDE EXPORT SERVICE RECORD DECKS 240 volt A
280. ers RF Capacitors RF Resistors Terminations RF Transistors Readout Tubes Receiving Tubes Rectifiers Relays Silicon Controlled Rectifiers ALSO AVAILABLE 501019 501019 5 501020 501074 801076 501077 501078 501080 501080 6 501080 7 501088 501089 501098 601115 501115 01127 01131 01133 501133 601134 501134 501134 501134 501135 501135 501136 501143 501143 501144 501158 501201 501202 501212 501212 501214 501216 501219 5012194 5012201 5012225 501222 57 0 501224 2 SD1229 F1 501229 STUD 5012446 01256 501262 501270 501272 501272 2 601278 5012781 501285 501300 5801303 501216 01317 01405 01407 01407 501410 60141021 01410 01412 501412 501413 501414 501416 501418 501421 501428 501429 Solid State Replacements Spark Gap Tubes Tetrodes Thyratrons Transistors Transmitting Tubes Travelling Wave Tubes Triodes Tube Sockets Accessories Vacuum Capacitors Vacuum Interrupters Vacuum Relays Vibrators Vidicons X Ray Tubes A replacement guide to dozens of Motorola Transistor part numbers Stocks of orlginal RF Devices from such manufacturers as MOTOROLA RCA GE TRW MSC ACRIAN TOSHIBA FUJITSU NEC MITSUBUSHI PHILLIPS AMPEREX and others CHIMNEYS CONNECTORS POWER TUBE ACCESSORIES FINGER STOCK SOCKETS ENQUIRIES Quotation for any types not listed S A E Cash Postal Order of Cheque with order CREDIT POSTAGE VAT Account
281. est Horsley Leatherhead Surrey You do your journal no service by continuing to publish these embarrassing articles by Dr Murray It is true that there are serious imperfections in both Relativity and Quantum Mechanics and if Dr Murray confined himself to explaining them to your readers one could not object even if one had doubts whether he was the man best qualified to do so But it is really too much when although apparently not able to offer any constructive comment himself he jeers at those men who have over the years painstakingly put these theories together Newton is supposed to have said tht he saw so far because he stood on the shoulders of giants No such humility from Dr Murray who can apparently see nothing from an even better vantage point The community of theoretical scientists Dr Murray s despised establishment is well aware of the imperfections of fundamental theory but is far from complacent about them On __ _ _ _ the contrary it continues to devise procedures for obviating them while at the same time looking for more fundamental changes which would remove them altogether A consensus is beginning now to emerge on what the basis of a new theory might be As usual in these matters the roots of the new theory go back a long way originally to Hamilton s quaternions but more significantl
282. ets include a received signal strength meter of some sort Often this doubles as a power level indicator The entry bar indicates a bar graph indica tor as distinct from a moving coil meter mc Receiver sensitivity the figure shown is where possible for the f m mode Power needs some hand held sets tolerate a wide range of sup ply voltages while mobile sets work best on the 13 8v provided by a reasonably healthy car bat tery Figures for current indicate the consumption on standby and while transmitting on high power Battery mA hour storage capac ity of the standard battery Most portable sets are supplied with nickel cadmium rechargeable batteries Batteries of other sizes may be available as an accessory many sets portable and other wise have a smaller battery not indicated here for memory ret ention Amateur Electronics UK 504 516 Alum Rock Road Birmingham 8 Tel 021 327 1497 6313 Yaesu Arrow Electronics Ltd 5 The Street Hatfield Peverel Essex Tel 0245 381626 NDi Lee Electronics Ltd 400 Edgware Road London W2 Tel 01 723 5521 Standard Lowe Electronics Ltd Chesterfield Road Matlock Derbyshire DE4 5LE Tel 0629 2817 2430 4057 Trio Belcom Microwave Modules Ltd Brookfield Drive Aintree Liverpool L9 7AN Tel 051 523 4011 Numerous preamplifiers power amplifiers converters and transverters Modular Electronics Ltd 95 High Street Selsey Chichester Sussex Tel 0243
283. explanations of other theories and facts Science likes a fundamental theory if it is felt on balance inexplicable things outweigh the unsatisfactory aspect of introducing new inexplicable idea and provided that it does not lead to inferences which conflict with observations In other words a fundamental theory has to be useful it must survive Occam s razor and it must be refutable by established facts Now the special and general theories of relativity wave mechanics gauge theories and so on are all fundamental in this sense All that their advocates claim for them is that if you assume them to be true you explain a wider range of facts than you can if you assume them to be false It is not a valid objection to a fundamental theory to say that it embraces a concept which clashes with your old preconceived ideas or that it cannot be derived from something else Science has always had trouble getting people to modify their tenaciously held ideas the sun revolves around the earth action at a distance 15 conceptually impossible and so on Even today people get stuck with wrong ideas through failing tolook at all the evidence a clockmaker would say that the great property of a pendulum is that its period is constant but a church bellringer would say that theone thing which makes change ringing possible is the fact that a small changein the amplitude makes a big difference to the period J G D Pratt W
284. ffices The party is now looking for ways to provide services and hardware support to those constituences Brian More of Dragon Data feels that the bouancy of the home computer market has been overestimated and that most people who get home computers do it purely and play games or because they are curious about computers He is looking for a buyer and one may be at hand Tandy Corporation whose Color Computer is very similar internally to the Dragon 32 has expressed an interest initially in taking over the servicing and repair of the Dragon but possibly in continuing the manufacture as well Camputers manufacturers of the Lynx computer which never really got off the ground having sold only some 10 000 units are also looking for a buyer The business computer market is now greatly influenced by the coming of the IBM personal computer Such large corporations can use their capital and their marketing expertise to produce a machine that is easy to mass produce and can provide full documentation and support in both hardware and software The smaller companies such as Tycom find it difficult to compete with such powers Software Key A fresh attempt to counter home Software piracy has been launched by the Cornish company Microdeal with the inclusion of the protection device with one of their latest computer games Buzzard Bait a game for the Dragon 32 comes with a small resin encapsulated module whi
285. for further 14kbit s development Overall bit rate 704kbit s 17 DIGITAL AUDIO Input Amount by which bit pair carrier changes phase 0 i e change 90 180 270 3 Rest states af carrier phase 90 apart Input bit stream bit pairs 10 11 Transmitted phase changes o 270 180 Rest states af carrier phase Fig 1 In the differential coding process four bit pair combin ations which modulate the car rier cause it to change phase by the amount shown in the table a Carrier has four possible rests state 90 apart b An example of carrier rest states adopted for the input bit pair sequence 00 10 11 and 01 is shown in c b 01 90 The carrier phase is assumed ta be initially in rest state 4 41 4 4 2 3 usually determines the carrier power required and cost The last item is particularly important here because it is highly desirable to minimize the cost of the dec oder required in domestic receiv ers The broad family of four phase shift keying systems offers the best compromise between the requirements above and a particular variant known as four phase differential or quadrature phase shift keying was chosen for the experimental system Four phase d p s k had been success fully used by the BBC in earlier contexts so experience had Frequency of second sound carrier Level of second sound carrier Modulation of the second
286. franchise should be the aquisition of BTs present telephone system assets This would privatize BT geographically piece by piece with the licensee operating a single system for telephones and tv Those awarded franchises should offer a common carrier service only and lease capacity for tv channels or other services to programming and marketing companies Control of such entertainment channels could be through the proposed cable authority These proposals would counter the problems found in the US where it has been found that cabletv only provides more channels and if those channels are also available over the air then the cable systems begin to founder Only in Washington DC has the telephone company proposed that they provide the cable system to be leased to cable tv companies That should be the way forward for Britain says Mr Partridge if it wants to learn from US mistakes and take its telecoms into the futue Communications in the air British Telecom persuaded British Caledonian to run part of its Gatwick operation from Birmingham at Communications 84 They did this to demonstrate the capabilities of Touchdown a communications link between the aircraft controllers and groundstaff which allows for the arrangement of schedules for re fuelling and repairs check destination and arrival times book crews and aircraft check passenger loads and the provision of on flight catering All this is done from a touch s
287. fset and alternate magnifier 375 00 2 Qual trace 20 MHZ lab port with sweep 5 CAT 00 375 422 Dual 40M HZ portable with DC offset and alternate amplifier 580 00 V353F 35 MHZ dual trace lab port with sweep delay 5v CRT 580 00 650 Dual 2 lab portable with dual lime base 850 00 Also In stock V134 storage VC6015 digital storage scopes Scopes Vector 4 TV monitor available CROTECH 3030 Single trace 15MHZ 95 component tester 169 oo 3132 Qual 20MM2 an 5 CRT Algebraic 2 mod plus component comparator and OC source outputs 283 00 3035 Single trace 10 MHZ comp tester 5 CAT TRIO 2 years warranty 6053310 Single trace 10 MHZ 5mV 75mm display Mains port 139 00 CS1562A Dual trace 10 130mm CRT 10 1 microssc with 2 probes 260 83 C3 1566A Dual 20MHZ 140mm 0 5 microssc with 2 probes 326 00 amp THANDAR aut noni 110A 10MHZ battery bench portable 10 32 x 8mm display Size 255 x 150 x 50mm 165 00 Optional carry cass 5 95 AC adaptor charge 6 95 Rech 11 00 EDUCATIONAL MIXED QUANTITY amp EXPORT DISCOUNTS We would be pleased to quote Contact sales oifice at 406 TRANSISTOR TESTER Direct reading PNP NPN and diodes leakage etc General purpose TCI 23 43 UK 65 PROBE KITS In wallets with adaptors a
288. g 1kW by using freshly cut date palm and coconut branches of length 1 5 and 3 metres respectively The vegetation cover with rea sonably good signal to noise ratio Anew simple method to tap the r f energy captured by the leaves branch was reported at the same time And most recently we Fig 1 Field receiving site ELECTRONICS amp WIRELESS WORLD JULY 1984 received signals from the Banga lore tv transmitter using a few live papaya trees one at a time only of height around 3 to 5m in length and located firstly at 12km and later 25km away from the trans mitting tower Experimental set up In this last experiment a few pap aya trees used one at a time of height around 3 to 5m were WWW americanradiohistorv com by S P Kosta K N Shamanna R Bhawani Shanker K S Rudralingappa V R Katti Y P Kosta Dr Shiv Prasad Kosta gradu ated from Jabalpur University and took his Ph D in Telecom engineering in 1969 at the same university Dr Kosta is a specialist on antenna and transmission line systems and has more than 120 research technical papers to his credit He takes keen interest in basic research problems relating to electrom agnetics antenna and micro waves and has guided students for M Tech and Ph D degrees Recently Dr Kosta conceived of using trees and salt solu tions as tv and radio antennas for very high and microwave frequencies Presently Dr Kosta
289. gineers and enthusiasts provides a c r t display of more than 3000 text characters 36000 picture elements or a mixture of text and graphics A visual display unit v d u passes information from a com puter to its operator It consists of a display device a monitor or a tv and digital circuits to con trol an area of memory holding a representation of the image to be displayed Data written into this memory from the computer is read out for processing and com bination with control signals to produce the necessary monitor input signals This being a vital part of a computer large scale integrated circuits of varying complexity have been produced to simplify the design of v d u digital circuits There are two fundamental types of v d u cir cuit memory mapped and i o mapped In a memory mapped system memory storing characters to be displayed on the screen is part of the system s addressable mem ory The advantage of memory mapping is that the processor can make rapid transfers to and from the v d u as fast as its own memory cycle which for a Z80B means 300 000 characters per second Also as the memory 1s under processor control it is relatively easy to implement unusual screen features such as scrolling the display left or down main disadvantage is that the v d u memory takes up memory available for programs unless paging is used and as the screen resolution and hence the amoun of memor
290. he DRE7100 2005 we pleased to offer another bargain package as follows BRAND NEW American MFE Corp in i iz ze E model 700 DOUBLE SIDED 8 Disc Drives AA on De Massive storage Capability up to 1 6MBytes Full IBM compatability External power requirements OSCILLOSCOPES arc 5V at 12 and 24V at 11 Full spares TEKTRONIX 453 Dual trace 50MHz 3 back up available U K Elcomatic s Current list DOLBY NOISE WEIGHTING FILTERS TELEGUEWENTD75 Dual trace 50 2 pem is over 315 Poa Cat No 98A Noise weighting filters for CCIR ARM HEWLETT PACKARD 1707ADual trace75MHz 180 INCLUDING MANUAL signal to noise ratio measurements As new units 40 each 1 p amp p TRIO CS1575 5MHz Dual trace 250 INC CARRIAGE amp INC VA ss RE uc Le TEST EQUIPMENT BECKMAN TURNS COUNTER DIALS MEGAPHONES EAGLE MV8SN New 40 DRE 4000 SERIES DRIVES Miniature type 22mm diam Counting up to 15 BEAVER Model E57500 Automatic test equipment turn Helipots Brand new with mounting instruc MARCONI TF868 LCR Bridge Data Recording Equipment 5 5 exchangeabie disc drives tions Only 2 50 each MARCONI TF2604 Electronic Mutti Meter 000 for 275 inlcuding power unit MARCONI TF893A Audio Power Meters 1000 WATT AUDIO AMPLIFIER 85 for inter factory office
291. he horizon 20 to 24 at the meridian to allow receiving stations to aim their aerials without the need for an elevation rotor Further information on these experiments is to be distributed through French stations on 144 170MHz 10kHz and 3670 10kHz Here and there The Australian society WIA has succeeded in persuading their Government to re establish the special low import tariff 2 on amateur transmitters and transceivers This concession was lost inJune 1983 when an Australian manufacturer of marine communications equipment complained that some imported amateur radio equipment had been modified and illegally sold for use in the maritime service The low import tariff was granted on the basis that there is no Australian production of amateur h f transceivers The Olympic Games torch run that starts on the East Coast of the USA and will pass through all the 48 contiguous States before it ends at the Los Angeles venue on July 28 is being co ordinated by amateur radio communicators travelling in the fleet of support vehicles under the aegis of AT amp T Several Australian amateurs have been granted experimental permits permitting transmission on 196kHz 1830 meters on condition that only backyard aerials are used With output powers of about 100 watts and fairly short aerials about 10m high resulting in effective radiated powers of less than 0 5 watt telegraphy contacts are being made over distances of
292. he most flexible computer cards around expansion cababilities are Impressive using the NASBUS and compatible BO BUS expansion cards Expansion includes hi res colour graphics full CP M disk system and much more Send SAE for full leaflets NASCOM 2 kit 225 00 NASCOM 2built 265 87 SOFTWARE MDIS INTELLIGENT 015 55 For all CP M based machines 50 00 HI RES For Gemini and others please enquire Provides Pseudo high resolution graphics 15 00 DISKPEN C Version 3 Low cost word processor for Gemini and others 018488 enquire 50 00 Plus large range or overlays for Olskoen HENRYS CP M UTILITIES DISK 4l Proprams for the CP M Systems programmer 574 format 15 00 8 format 17 35 Ask for details on all of above WHEN OROERING PLEASE SPECIFY FORMAT REQUIREO Contact Computer Dept If uncertaln C Copyright Cubegate Ltd all rights reserved All above available 10 retailers and distributors contact Computer Dept for details COMPUTER POWER SUPPLY Switched mode Stablilsed Self protecting S C protected etc 220 240V 5V 3 12V 2 44 40 cycle 5V 0 54 12V 0 54 Suitable Apple replacement COMPUTER FANS CU7983 115V 50 60Hz 12 13W Impedance protected use 2 in serles for 230 44 x4 x1 Two for 8 70 UK 70p 220 240V as new only 4 78 UK 500 each 2020 CS Professional computer case 2 18
293. her than constant relative velocity Einstein s early success 1911 in deriving the red shift formula for a gravitational field could only be explained by assuming he used relative instantaneous velocity Finally does the wavelength change under conditions of relative motion between a light source and observer while the velocity of the light is constant The constancy of wave length and associated wave number is an unwarranted carryover from classical physics and even Einstein himself showed his conservative nature is making this latter assumption G Blondeau CANMET Dept of Energy Mines amp Resources Ottawa Ont CANADA Tam beginning to get the hang of much that you have recently printed in spite of the titles it has had nothing to do with relativity Science comprises a considerable body of facts and theories which support one another and which are widely considered to be true This body can grow in two very different ways We may wake up to new implications of what is already accepted new that is in the sense that no one had got round to digging them out before or we may add new facts which fit in to the old body and so consolidate it That is we may build on the old structure But we can also work on the foundations Some of the theories in science are fundamental which means that their truth cannot be inferred from other accepted facts or theories their sole purpose is to provide
294. histicated computer controlled test gear for production testing of our products Future test equipment will be an Interesting mix of digital and analogue circuitry aimed at increasing the automation of the production testing operation If you are able to conceive design and implement production test equipment with minimal supervision we d like to hear from you These positions are based in our Chessington Engineering Centre but some visits to our factories in the North East and Lancashire will be required at infrequent intervals Salaries are obviously dependent on qualifications and experience but will reflect the importance of future test gear projects to the Company s long term development Interested 2 Then write or phone Harry Brearley Rediffusion Consumer Manufacturing Ltd Fullers Way South Chessington Surrey KT9 1HJ Telephone 01 397 5411 REDIFFUSION 2408 ELECTRONIC INSTRUMENT FIELD SERVICE TECHNICIANS Sartorius Instruments is a world leader in electronic weighing in the research quality assurance and allied industries The product range is expanding fur ther into industry and personnel are required to supple ment our already established Field Service team Areas with a vacancy include the South Midlands and Northem home counties plus a relief engineer prepared to travel nationwide Successful applicants will service and install our elec tronic we
295. hm with carry case leads etc YF501 59 13 UK 65 Shop HENRYS 404 406 Edgware Road London W2 Computers 01 402 6822 Equipment 01 724 0323 Components 01 723 1008 Shop AUDIO ELECTRONICS 301 Edgware Road London W2 Test Equipment Audio Communications 01 724 3564 All mail to Cubegate Ltd 151 Floor 406 Edgware Road London W2 RETAIL MAIL ORDER EXPORT INDUSTRIAL EDUCATIONAL DIGITAL CAPACITANCE 2500mtd 6 ranges _ 220 240V AC UK 4 ins 1 00 Banch portable all sine square triangle TTL etc External sweep mode FUNCTION Thandar 16101 0 02HZ to 200KHZ various facilitles 105 00 Thandar TG102 0 2 2 to 2 2 various facilities 155 00 Jupiter 500 0 1 Hz 500 KHZ 110 00 Thandar Pulse Bench portable T6105 5 2 to 5MHZ Varlous acillties 105 00 Optional carry case 5 95 AUDIO Loader LAG27 5 band sine square Q P 0 5V RMS Olst 0 05 10H2 to 1MHZ Leader 61204 5 band 10HZ to 1MHZ to 0 3V AMS Into 600 ohm 0 05 dist sina squara 145 00 Leader LAG125 5 band 10HZ to 1MH7 to 0 3 RMS Into 600 ohm sine squara burst signals 0 03 dist 330 TRIO AG202A 4 band 2087 to 200KHZ 10V RMS O P 0 5 dist OSC 0 10V PP 0 89 00 TRIO A8203 5 band 10HZ to 1MHZ 0 1 dist RMS 0 P 139 00 TRIO 8402 6 range 100KHZ to 30MHZ RF 0 1V RMS Int ext mod 72 00 Leader 18817 6 band 100KHZ to 150MHZ 06
296. ied with demo and development programs on cassette and full software instruction 37 2 50 BBC EPROM PROGRAMMER timer Both offer full built in safety It can handle up to 5 eproms at a time with an average erasing time of about 20 mins 59 2 p amp p UV1 as above but without the timer 47 2 p amp p For Industrial Users we offer UV140 amp UV141 erasers with handling capacity of 14 eproms UV 41 has a built in UV140 61 UV141 79 p amp p 2 50 taneously with device sizes up to 16K X 8 bytes Devices supported range from 2704 to 27128 in single and three rail versions Simple menu driven operation ensure easy eprom selec tion and reliable programming mini mum programming times 695 6 carriage features CONNECTOR SYSTEMS Eprom programming and develop ment work EP 8000 can emulate and program all eproms up to 8K X 8 bytes can be used as stand alone unit for editing and duplicating EPROMS as a slave programmer or as an eprom emulator 695 a A fully self contained mains powered eprom programmer 1 0 CONNECTORS JUMPER LEADS AM PHENOL RIBBON housed in an attractive finished case It is able to program Speedblock Type 47 Ribbon Cable with Headers 2716 2732 32A 2764 amp 27128 s in a single pass It is sup Noof Header Recep Edge 14 16 24 40 pin N ECTORS CABLE plied with vastly superior software wh
297. ifying transis tors The waveforms of the sys tem are as shown in Fig 99 and the display picture shown in Fig 100 illustrates before and after the application screen photograph taken from a Mullard publication Picture enhancement with colour transient improvement circuit Itis possibleto improve the R GB signal where the chroma band width has been restricted to supp ress crosscolour resulting in risetimes in excess of 500ms On improving speeding up the rise times care has to be taken not to exaggerate the crosstalk e g increased U V 12 5Hz flicker By using a switched equalizer under the control of the differen tiated luminance signal to mini mize cross colour increase the U and V i e B Y and R Y chrominance steps be improved This is possible because of the good correlation between the luminance and chrominance picture informa tion i c to improve colour transients is the Mullard TDA4560 shown in Fig 101 This uses the differentiated input R Y and B Y chroma to con trol and chroma delay switching The effect of using such tech niques is for a chroma positive going transition as seen in Input Chroma transition Subjectively improved rise time i Delay switched out Additional delay added Fig 102 Waveforms showing chroma edge enhancement by delay switching Timing delay adjustments ensure video transition corresponds with scan velocity modula
298. igh levels to the modulator input The output from the demodu lator pin 7 which is applied in ternally to the input of the v c o needs to be filtered for the p 1 1 to operate satisfactorily This 15 achieved in this circuit by the 27nF capacitor connected between pin 7 and the 15V sup ply rail For the chosen v c o operating frequency of 10kHz and a rate of 2400 baud this value has been found to be satisfactory Itis also satisfactory for lower rates but possibly not for a higher rate of 4800 baud Unfortunately I have not been able to try this out To provide t t and RS232 type output level theoutput from the demcdulator on pin 7 needs to be amplified This is achieved using an op amp as a comparator and the output from pin 6 as the reference level The output from pin 7 is further filtered by the sim ple two stage ladder filter com posed of 5 6kQ resistors and 4 capacitors The band edge of the ladder filter is chosen to be approximately half way between the maximum keying rate 2400 baud or 1200Hz and twice the input frequency about 20kHz 1 capacitor connected between pins 7 amp 8 acts in the same way as that between pins 6 amp 5 of the 566 i c i e to improve high frequency stability Similarly the capacitor across the inputs of the op amp comparator does the same thing The 1MQ resistor connected from the inverting input of the op amp to the 15 volt rail ensu
299. ighing instrument systems Primary responsibi lities will be problem solving of Sartorius equipment con tract maintenance and customer liason Education to a suitable allied qualification ie C amp G TEC Electronics is preferred for the relief engineer A successful trouble shooting ability in electronics exper ience of balance scale service or maintenace of fine instruments is otherwise necessary On appointment you will spend 4 weeks training in our workshop in Belmont Candid tes must be in possession of a current driving licence and ower 23 years of age A company car is pro vided In additional to the above vacancies trainees are required for general electronic and mechanical balance maintenance at our in house service centre at Belmont Surrey If you would like to apply for a position Please write for an application form to the Service Co Ordinator Saratorius Instruments Ltd 18 Avenue Road Belmont Surrey Telephone No 01 643 8870 2621 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com EARLY RESPONSIBILITY IN ELECTRONICS Are you recently qualified HNC H TECH or DEGREE with hands on sandwich or work experience in both analogue and digital circuitry and electronic test knowledge and with the abil ity to programme in Basic Thenif you have theinitiative to take responsibil ity forthe design construction and maintenance of specialised and proprietary test equipment c
300. integrated Circuits Klystrons Klystron Amplifiers 25 2290 25 2347 25 2369 28C2370A 25 2379 25 2395 25 2407 25 2420 25 2494 25 2509 25 2531 25 2538 25 2539 25 2540 25 25456 9 BFROY BFR96 BFY90 BLw29 BLW60C BLW6EOCF BLW64C3 BLW78 BLW80 BLWB1 BLW90 BLw98 39 BLX65 8LX67C 85 67 BLX68C3 BLX6BCF BLX69A BLXS4A BL X98 BLYB7C BL YB8C BLYBBCF BLYB9C BLY90 BLYSICF BLY94 MRF208 MRF212 MRF221 MRF229 MRF231 MRF232 MRF233 MRF234 MRF237 MRF238 MRF239 MRF240 MRF243 MRF245 247 MRF260 MRF264 MRF309 MRF316 MRF317 MRF321 MRF323 MRF326 MRF327 MRF329 MRF412 MRF421 22 MRF426 MRF427A PRODUCTS Magnetrons Microwave Tubes MRF428 2 MRF433 MRF449A MRF450 MRF453 MRF453A MRF454 MRF454A MRF455 MRF455A MRF458 MRF466 MRF472 MRF475 75 MRF492 MRF497 MRFS15 MRF517 MRF620 MRF544 MRF646 MRF64B MRF750 MRFB46 MRF90 MRF904 MRF911 MRF5175 5176 MRF5177 MRFB004 PT3134A PT3134B PT3134C PT31340 3134 PT3161A PT316 B PT3161C PT31610 PT31 61F PT3503 PT4261A PTA2618 PT4261C PT43 6C PT43180 PT4316E PT4316F PT5661C 8751 20 PT883 PT8837 PT8838 PTBB8S4B PT8861A PT8864A PT8874 PT9795 9797 PT9841 PT9847 501005 501006 501012 3 501012 4 501013 5010346 501015 501018 6 Microwave Semiconductors Photomultiplier Tubes Phototubes Planar Triodes RF Amplifi
301. into several broad per formance areas aS we would expect from the previous look at fibres sources and detectors The majority of installations have operated at a wavelength of around 0 85 using medium performance graded index fibre with silicon avalanche photode Modutator driver Modulator Information Source ps Transmission medium tector receivers Fig 2 Where the main consideration was not maximum repeater spacing l e ds have normally been used because of their lower cost resulting in repeater separations of around 6km in the 30 45Mbit s and 7km in the 100 140Mbit s range The latest phase of the first generation systems has seen the use of the dispersion null at 1 3m with low attenuation fibres resulting in even greater spacings for medium data rates An additional advantage aris ing from the increased repeater spacings is that well over 5096 of the connections between major Switching centres within cities can now be made repeaterless with an increase in reliability and decrease in cost This has also been the pattern of experience in N America Europe and Japan Optical fibres are not usually laid as a single fibre Instead a number of them eight being common are made up into a cable around a steel strength member Output amplifier Preamplifier Information Electronic systems Optical systems ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradi
302. io Electronics Henson House of Instruments 2 2 2 ILP ElectroniCS 48 Langrex Supplies Ltd 90 Levell Electronics 92 Opus Supplies 59 63 82 PM Components 78 79 PyeUnicam 5 e ren Inside Back Cover PAGE Radford Electronics esee 36 Radiocode Clocks 221 Radio Components specialists 60 Radio Society of Great Britian 70 Electronics 82 Research Communication Ltd 20 Robot UK Ltd sees 8 RSIValv ce en 90 Sherwood Data Systems 92 Sowter Ltd 84 South Midland Communication 68 Special Products Distribution 54 Strumech Engineering 10 Stewart of Reading 42 Surrey Electronics Ltd 2 2 2 2 6 Taylor Bros eerte eoe neenon 1 4 02 Thander Electronics Ltd Thanet Electronics Thorn EMI Instruments Thurlby Electronics 2 Valradio Power Ltd 2 2 4 15 Vigilant Communication 24 Whiteley Electronics Wings Appeal
303. ired for Tr The capacitors in the line interface may have to withstand ringing voltages and transients on the line and so it is important to fit suitably rated types for the prototypes 250V metallized film capacitors were chosen If the constructor does not intend to add an auto dialler there is no need for RL RL or their associated components R g R and C but a wire link should be added in place of the contacts of RL The spark gap across the tele phone line is included for safety although some commercial modems do without It should be able to withstand the voltages developed during ringing without breaking down Suitable types are available from Electrovalue Ltd LSI circuits for teletext and view data the Lucy generation Mullard Technical Publication M81 0001 June 1981 The auto answer circuit is iso lated from the line by an opto coupler The zener diodes are to protect IC against damage by over voltages and to define a threshold level below which it will not respond n a c ringing vol tage causes the level on pin 3 of the inverter IC to fall trigger ing the monostable The tele phone will continue to ring for a few seconds until the second monostable is triggered by the rising edge at pin 4 At this point pin 1 of the Am7910 is pulled low causing it to begin its answering sequence and the line seize relay RL closes The time constant of the second monostable is
304. itterns Westbourns WAT GPT 2537 TURN YOUR SURPLUS i 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 PROFESSIONAL DESIGN SERVICE Ana logue RF circuit System design Specialising in microwave amplifier oscillator and network design MOTOROLA 6805 6809 series micropro cessor design development capability All work carried out to a high standard by competent profes sional engineers Trontech Electronics Design Services 81 Finchampstead Rd Wokingham Berkshire Tel 0734 790103 2439 1391 DESIGN AND MANUFACTURE ANALOGUE DIGITAL RF AND MICROWAVE CIRCUIT AND SYSTEM DESIGN Also PCB design mechanical design and prototype small batch production Ad enmore Limited 27 Longshot Estate Bracknell Berks Tel Bracknell 0344 52023 656 DESIGN AND DEVELOPMENT SERVICE RF transmitters and receivers Telemetery U H F V H F Anologue and digital circuits control sys tems Full manufacturing facilities RCS Electron ics Wolsey Road Ashford Middx Phone Dr Eric Falkner on 53661 2637 SMALL BATCH PCBs produced from your art work also DIALS PANELS LABELS Camera work undertaken FAST TURNAROUND De tails Winston Promotions 9 Hatton Place London ECIN 8RU Tel 01 405 4127 0960 9797
305. l also start up before its schedule date of March 1985 initially covering London cities inthe south Wales and the midlands and along several motorways The second phase is to bean expansion into the north of England plans for Scotland and Northern Ireland are to be announced later this year Racal have also launched a new company Racal Vodac to distribute install and service subscriber equipment Another company was necessary as the licencee for the system is not permitted under the terms of the licence from marketing the consumer equipment Consumer equipment for the BT Securicor Cellnet system is system interrogates the key which responds only if the correct password is used Any copy ofthe software will only work on a computer fitted with the same key and as there are approximately 100 million possible codes made up out of ASCII control characters in effect this means only one computer can use it Each device is supplied with a randomly selected code together with notes and a flow chart on how to incorporate the interrogation routine into a program It has been estimated that it would take fast computer about 20 years to crack the code WW230 to be manufactured in Japan by NEC After a world wide search for a manufacturer to these products BT decided that NEC were the only people with the facilities and expertise to provide the system The equipment will include both car mounted mobile radiophones a
306. l vertical and cheap and reliable data storage Supplied in tested prior to despatch Dimensions in typ ONLY 2 MINUTES Interna 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 tDIOT adjustable baud rates quiet operation plus Options Floor stand 12 50 Supplied complete with circuit 240 volt AC PROOF operation ONLY 395 00 PP 3 00 many other features Supplied complete KSR33 with 20ma loop interface 125 00 operation ONLY 45 00 PLUS 9 50 CARR Data sheets on request with manual Guaranteed working 130 00 or Sound proof enclosure 25 00 _ 24 CASED Again made by the untested 85 00 optional floor stand 12 50 th a similar spec as the 12 monitor COLO MO Carr amp Ins 10 00 PROFESSIONAL KEYBOARD OFFER Originally teed for large screen data NOVEX NC 1414 CL Fully cased brand new An advantageous purchase of brand new surplus allows a great QWERTY full travel display ranwa gnt chassis keyb offer at fractions of their odindi cote are case aim 287 pA E ei 4 col L tC 7204 60 ASCII 60 key upper lower control parallel TTL MES PA REB TTL Output plus strobe Dim 12 x 6 5 amp 12 DC 39 50 ideal unit for schools clubs inputs Internal speaker and audio amp DEC LA34 Uncode
307. ld be inexpedient to demonstrate that their uncritical commitment to relativity theory may have been mistaken C B V Francksen Farnborough Hants XY PLOTTER Iam prompted to write to you because of the very interesting XY plotter by P N C Hill Iam retired now from running a plastics injection factory but have long been keen on electronics photography astronomy For a number of years Ihave been experimenting with a method of printing colour photographs direct on to paper by scanning as in the facsimile process This started with EF50s and multiplier cells and progressed to transistors and has involved many different models using ballpens and also carbon paper for the image I even tried a mixture of metal indicators soaked into paper with glycerine and electrodes of copper nickel and molybdenum to mark the paper So far the carbon paper has seemed the best to manage with limited funds to spend on research Inthe course of these experiments I have used various steppers including the Clo Syn motors from Stewart Not being good enough with logic circuits I have had to use simple chips like the 4017BE which give a decade count from simple pulsing and can be made to count lesser steps by reset from one of the outputs The 4017 is used for 400 steps by the circuit shown in my sketch A useful chip is the SAA1027 which will drive a Slo Syn motor andreverse in an easy manner but my circuits have been mainly for uni
308. le i c for colour transient improvement taken from the data sheets for the TDA4560 Vp 12V Luminance input signal Clamping circuit Gyrator delay ceils Y output ty r Colour afterence input signals 250 ELECTRONICS amp WIRELESS WORLD JULY 1984 Differenhating stage Differentiating stage Switching Integrator stage pulseformer gt t stage Switching and storage stage 2220 WWW americanradiohistorv com and storage Velocity modulation output ty 90 5 R Y m Typical output transitions 150ns 2220 41 MAINS ISOLATORS Pri Sec 120V 2 20 5 82 1 50 60 949 1 80 100 11 08 2 00 200 15 59 225 250 18 97 2 64 350 23 41 2 70 500 2923 2 95 750 4128 370 1000 53 00 400 1500 6837 470 2000 27 5 10 3000 115 35 0 5000 20365 0 4115 240V sec only 400 440 ISOLATORS 400 440 to 200 240 60 9 50 1 80 100 11 08 2 00 200 15 68 225 250 18 97 2 40 350 23 47 2 10 500 29 23 2 95 1000 52 98 4 00 2000 5 00 300 11537 0 6000 228 75 0 24 12 or 12 0 12V 2x12V Secs Pri 240V TN 24 Price P amp P 50 25 or 25 0 25V TRANSFORMERS 100 459 27 30 15 15 0 15 250w 154 93 500W 239 50 2x25V Tap Seca 5 7 8 2x15V Tap Sec Voits 10 13 15 17 2 25 30 3 4 5 6 8 9 10 12 15
309. lectromag netic interference and the lack of fire risk in sensitive areas The range of parameters that can be measured can conveni ently be classified into mechanical force pres sure deformation Nelectrical field strength polarization current magnetic field strength polarization temperature In most cases these measurands produce changes in the refractive index or in the absorption of the fibre but some of them will modulate luminescence effects The table presents information on the categories of modulation and detection that may be used with each of the five different opti cal parameters Some of the most sensitive fibre sensors constructed use an interferometric technique in which the optical phase shift pro duced in a fibre by interaction with the measurand is compared to the phase of a reference arm Rotation sensors gyroscopes with sensitivities around 10 2 degrees per hour are currently operating Similar techniques can be applied to phase shifts pro duced by pressure changes on the fibre resulting in acoustic hydro phone sensors with higher sensi tivities than piezoelectric types Magnetic fields can also be detected by phase techniques if the optical fibre is coated with a magneto restrictive material Mechanical displacement can be measured by several arrange ments of intensity sensing between movable fibre ends either with an orthogonal or a slant cut Vibration detection
310. lem of interpretation ofthis assertion in terms of experience is the real stumbling block for relativity theory the late Professor Herbert Dingle strongly suggested that no meaningful interpretation is possible Some further propositions which readers may like to comtemplate are 5 A unique universal medium or aether propagates radiations at the velocity c 6 Material conglomerates moving through the aether of 5 suffer spatial contractions along the axis of motion in proportion toits rate and concomitantly their internal processes are retarded In his 1905 paper Einstein recognised the Lorentz Fitzgerald contraction time dilation effects as consequences of 2 the former effect being considered as apparent and the latter as real which was a blatant inconsistency The development of the General Theory requires the Lorentz Fitzgerald effects to be physical it is not generally stated that this in turn produces difficulties with the dynamics energy possessed by rotating entities and the ELECTRONICS amp WIRELESS WORLD JULY 1984 Www americanradiohistorv com development of the theory to require an increase of mass with increase in velocity through the ether violates the principle of energy mass conservation Some further propositions are 7 Electromagnetic radiation emanates from every emitter with a velocity relative to that emitter and remains directly related to that emitter indefinitely i
311. listing enables the user to add any particular programming needs as may be required The programmer card is the same cost as the TDS 900 c mos computer both are 179 95 Triangle Digital Services Ltd 100A Wood Street London E17 3HX EWW 223 85 LINSLEY HOOD 35 Watt Complete Kit MosFet 79 50 45 Watt Complete Kit MasFet O P 83 50 Reprints of Original Articles from Hi Fi News 1 VAT 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 412mm wide 254mm deep and 145mm high Automatic switched speaker protection is included as standard Cost of ail parts is over 120 Our complete stereo kit price 105 50 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 and 50 postage STEREO AMPLIFIER MODULE Ready built and tested quality power amplifier module complete and ready to use Mains input 220 240v with power to spare for tuner and tape deck Size 190 x 110 65mm TUNER AND PRE AMP MODULE Matching unit to above Contains Long medium and short wave AMtuner Stereo FM tu
312. lso manufacture chargers which range up Vaseline Spray K90 Video Spray 33 Graphite Spray 100 Antistatic Spray K101 Fluid Spray and of course Positiv 20 positive photo resist for printed to 60 amps URS For further details please contact E M S Manufacturing Limited Chairbarough Rosd Special Products Distributors Ltd 81 Piccadilly London W1V OHL H g h Wyco m be Tel 01 629 9556 Telex 26500 answerback RACEN Bucks Cables Speciprod London W1 Tel 0494 448484 Details from CIRCLE 11 FOR FURTHER DETAILS CIRCLE 32 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com OPTICAL FIBRES Fibre optics communications by Brett Wilson Part 3 Systems and applications This last article in this three part series looks at the range of applications in which fibre optic sys tems are being introduced In view of the very low energy levels involved in fibre optic transmission they are best suited to the transfer of information rather than power It is in this area that they are making a major impact even at this relatively early stage of their development Indeed British Telecom has recently announced that it will be ordering no more coaxial cable after 1985 for the telephone network due to their growing commitment to fibre optics It has been predicted that over half of all trunk telephone traffic will be carried on optical fibres by 1
313. ly developed since it was first introduced This new edition has been re written to include as well as the basic introduction to the subject an up to the minute account of such innovations as satellite and cable flat panel receivers 3 D displays and digitization of TV signals 4 50 Softcover 160 pages 13 95 COLOUR TELEVISION SERVICING Second Edition Gordon J King Softcover 192 pages Softcover 350 pages 11 50 Order from your Bookseller direct from Newnes Technical Books Borough Green Sevenoaks Kent TN15 8PH CIRCLE 37 FOR FURTHER DETAILS Jackfield Wiring STEREO STABILIZER STEREO PRIQUEMCY SOFTER M DUC Me ic Rack mounting frequency shifter for howl reduction in public address and sound reinforcement Mono version box types and circuit boards also available SURREY ELECTRONICS LTD The Forge Luck s Green Cranleigh Surrey GU6 786 Telephone 0483 275997 FREQ CONV I P 240v O P 115v 400c s 1 phase 100 Va sine wave new transis unit 85 RTTY Test Sets ATE type TDMS 5 or 6 mains operated 35 ea NOISE GEN CT207 1053 100 600mc s mains operated with book 35 POWER UNIT bench p u to oper ate ARC 52 set mains provides semi stab O P of 28v DC at 15 amps tested 38 POWER SIG GEN mains operated self contained in rack case tunes 1 5 to 12Mc svar RF O P approx 20 watts into 75 ohm metered O P direct cal with 75 DUMMY
314. m LTD SAE for LIST TEL 0934 41 6033 by appointment 34 Rod abet and enquiries Kent 1 3JL SS SL NE SSS ee CIRCLE 23 FOR FURTHER DETAILS CIRCLE 57 FOR FURTHER DETAILS 36 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com TELEVISION Improving colour television decoding Viewing tv pictures at work and at home over several years using various decoding methods David Read found the comb filter method an undoubted improvement with a 26in screen But inprovements to other video processing blocks are needed to fully appreciate the picture This postscript recommends an acoustic surface wave filter for i f use and discusses other picture enhancement techniques Most of the signal processing improvements that the home viewer can make to PAL decoding RGB drive and wide band comb filtering have been covered in this series of articles One remaining area for investiga tion is the tuner i f strip Although the ten years old design originally described in these pages 1975 Oct Dec is still in use and gives good results parti cularly with extended comb filter methods of PAL decoding it is felt that the design and circuit board cannot be recommended for building today with dis crete inductors providing all the i f bandwidth shaping and post demodulator group delay equali zation It has been remarked that the board looks more like a Man hattan sky line There is also a
315. many other factors including resistance to overloading resistance to out of band signals and the quality of the filters The sensitivity figures should not therefore be taken on their own as an index of the receivers overall merit As it is with cars so with transc eivers even the cheapest will get you from A to B if the road is open So what are the advantages of buying one of the more expen sive models With radios even the costliest cannot offer extra speed But it can provide a range of features designed to make a session at the microphone more interesting and less tiring Among these are extra memo ries for storing commonly used frequencies additional scanning modes accessories such as a voice synthesiser to supplement the front panel display plug in radio frequency modules for other bands an interface unit enabling the transceiver to be controlled automatically by the users computer and of course more transmitter power and a better receiver Notes on the table Price the distributor s UK price including v a t Style entry indicates whether the set is intended for portable mobile or base station use How ever for many mobile units it is possible to buy desk top consoles with mains power units and for some portables car fixing kits are available Modes f indicates narrow band f m s indicates s s b c indi cates c w Other bands this survey includes one or two dual band models
316. matic scan synchronization semi automatic picture acquisition and the selection of a specific part of the image for storage in the memory Apart from its obvious uses in weather prediction the system may be used as a teaching aid in geography and in the study of the technical and engineering aspects Each equipment is supplied with a comprehensive installation and operation manual as well as information on satellites and the prediction of orbits Feedback Instruments Ltd Park Road Crowborough East Sussex TN6 2QR EWW 205 EPROM EMULATOR For usein conjunction with their E series of editing eprom programmers Elan have introduced the E11 eprom simulator which can speed up program and hardware development by simulating a target eprom Programs may be run checked and easily altered before being committed to permanency in a eprom One E11 may be used to simulate any of the current range of 24 and 28 pin devices including 2716 2732 2764 27128 and 27256 Two units in a master slave configuration may be used to provide twin eprom simulation or 16 bit simulation The is available in two versions one up to 16K of memory 27128 the other up to 32K 27256 Data is entered into the main programmer which is connected ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanraciohi to the E11 thetarget eprom and to the microprocessor control system The E11 has an access time typically of 175ns On
317. modulation is more or less dead on v h f despite one or two attempts to revive it the few stations still using a m equipped mostly with second hand commercial radiotele phones The multi mode set also makes a useful building block for forays into the higher bands by providing a stable frequency source for multiplying up through devices such as varactor triplers Technical features Commercial amateur radio equip ment has changed considerably during the last few years Perhaps the most conspicuous develop ment in v h f transceivers at least is that digital frequency synthesizers have almost entirely displaced switched crystal oscil lators and free running variable frequency oscillators True continuous tuning has become virtually a thing of the past in 2m equipment Most sets TRIO FM DUAL BANDER tune in steps governed in the first instance by the frequency of the synthesizers v c o With f m equipment for the European mar ket the step size is often 12 5 or 25kHz This gives easy tuning of the numbered f m channels on 2m which are spaced 25kHz apart So an f m only set which scans in smaller steps may be awkward to handle when rapid retuning is called for However in many synthesized sets the chan nel spacing can be programmed by the user On s s b tuning steps as small as 100Hz are the norm But s s b sets also have a clarifier or receiver incremental tuning con trol r i
318. mulative recycling and thus prevent excessive blur For the domestic receiver a simple enhancement technique is to modulate the line scan velocity Fig 92 Component location for PAL modifier comb filter board It is useful to check the coil bases with the board before winding any coils particularly the center tapped ones Chip provides additionally the 2 fsc feed required by the PAL modifier in Fig 34 The sandcastle pulse to the TDA35614A can be supplied from the TDA2591 2 3 These two signals may already be available in existing receiver designs but check that it is a 2 locked oscillator if this signalis to be extracted Set for max chroma at TP and min 78k gu transitions m fs Modifier a E 2 2 links for 180 266 phase Field 175 blanking 18 59 _ Space for on board regutator fj 15 625kHz Carrier balance on M1596 Set amp 433MHZ Link for isolating with feton lum fitter output Link for isolating tum filter input Adaptive notch threshold ELECTRONICS amp WIRELESS WORLD JULY 1984 ATTENUATION dB 4 1 uhf input f test O Channel select bcd thumbwheel switches Remote select Phase shift set Signal if demodulator Carrier f 335MHZ foc sound carrier GROUP DELAY ns 50155 100 055 22
319. n Centre on 13 and 14 April 1985 A postage stamp featuring the amateur radio station H44SI of the Solomon Island amateur radio society was issued last December as one of a set of three stamps forming a World Communications Year set During early June French amateurs operated a special station TK6JUN at Ste Marie du Mont Utah Beach to mark the 6 June 1944 D Day landings by Allied forces On this side of the Channel GB4BLC operated from the Royal British Legion centre at Nettley Southampton as part of an Operation Overlord project during the D Day anniversary week RSGB annual subscription is being increased by 2 to 16 50 fromJuly 1 In a recent prosecution for the illegal use of 6 6MHz transmitter Robert Burwell was fined 250 with 50 costs It was stated that French air traffic control had complained of interference to its operations caused by the transmitter July mobile rallies include Worcester club at Droitwich High School Ombersley Road onJuly 1 West Manchester club at Burtonwood Motorway Service Area near the junction of M6 and M62 on 8 July Cornish club at Camborne Technical College Pool on 15 July West Kent Radio and Electronics Fair at Royal Victoria Hall Southborough on 21 July Anglian rally at Stanway School Colchester and McMichael rally at Bells Hill Stoke Poges both on July 22 Rolls Royce rally at Sports amp Social Club Barnoldswick and Scarborough rally at The S
320. n appear together at the end of the pipeline see the timing diagram The controller provides a register for positioning a cursor which can be made to flash a register for use with a light pen and a facility for inter laced video Together with multi VIDEO ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com 0 1 9 5 7 LEJI Q Q LOES X 9066 9 5 VILSTIL SLE Sots JNASA 4 9851 JNASH 99451 10651 405 6LE3 E 7 EJ 2 L i 089 089 Wey dzz z 1 1089 ZHWZL 0 LOt1g Y DOL 06 bg 94 09 55 07 DE e of uw te 0 949 20 yt 59574 454517 7 iy 1515182 MEJ LSSI 60E 3 33 WWW americanradiohistorv Sw ITEM by Gy Oy DARE 5 as ps Ag LE PUD DLE 27 02 ISNA Thy Ely 22 Pun oze SION3M 261 200 092 052 07 DEZ 977 002 DIZ 081 96 091 0 06 27 DEL 221 00619 ELECTRONICS amp WIRELESS WORLD JULY 1984 VDU timing Synchronization in this v d u using pipelining see text is critical and depends on two signals NOT CARRY and the dot clock Dot clock 12307 pin 6 I SPECIAL FEATURE plexers selecting memory c p u or controller lines some high speed logic too fast to build into
321. nction so it is provided on the board an inter rupt pulse is sent to the STI at the start of the strobe pulse and after a pause of approximately 0 5s further pulses occur at approxi mately 20Hz Overall speed ofthe repeat system may be adjusted by changing the capacitor value the 0 5s hold off only may be adjusted by altering the 390kQ resistor and the repeat frequency by altering the 1 8kQ resistor In all cases reducing the value increases the speed of operation The i c used for keyboard repeat IC also supplies the 2 4576MHz signal for bit rate generation 1 recommend that you avoid a National Semiconduc tor part for this i c CD4093BE RCA or MC14093BCP Motor ola being suitable Table 2 Interrupt vectors in memory Address OFFOO 0 02 9 04 OFFO6 OFFOC OFFOE OFF10 OFF12 OFF14 OFF16 OFF18 OFF1A OFF1C OFF1E 1 0 line 2 Timer D Timer C line 5 Timer B Receiveerror Timer A Service routine 1 0 line 0 keyboard interru 1 Oline1 P line 3 pulse width event B line4 pulse width event A Transmit error Transmit buffer empty Receive buffer full line 6 disc controller INTRQ line 7 disc controller These are addresses of the two consecutive locations in memory at which the interrupt controller will expect to find the starting address of the service routine for that particular interrupt the driven pin the cath
322. nd hand held portables The mobile sets will be available in December this year with the portables following later in 1985 If the cellular system is as successful and popular as both BT and NEC think it will be then there is a chance of manufacturing facilities being transferred to the UK The first working pilot system of Cellnet was to be demonstrated in London early in June to cover 3 000 square miles and give continuous coverage over central London extending to Heathrow and Gatwick Airports ELECTRONICS amp WIRELESS WORLD JULY 1984 THE SOURCE Electronic Brokers 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 meet 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 BRYANS TEKTRONIX SOUTHERN Logic Analyser XY T Recorder 7001 with DF tore annels up to A y 1024 words deep State A4 Size 100MHz sample rate X Y Ranges 1mV to 1V Per CM Price 2 000 Slew Speed 49 CM Second 1 Timebase 0 1 to 10 Price 750 Illustrated with 7603 d ro Mainframe Extra Hu MS ENSE 37 e 178 Linear IC Test for
323. ner and pre amp with switched inputs for tuners tape and pickup Complete with flywheel drive and cord assembly Size 400 x 220 x 63mm Special offer for both items only 16 90 300 SERIES AMPLIFIERS LINSLEY HOOD CASSETTE RECORDER CIRCUITS Complete record and replay circuits for very high quality low noise stereo cassette recorder Circuits are optimised for our HS16 Super Quality Sendust Alloy Head Switched bias and equalisation to cater for chrome and feric tapes Very easy to assemble on plug in PCBs Complete with full instructions Complete Ste ca Bacord Play ME HIE eae 25 26 VU Meters tosuit 2 30 each Reprints of original Articles 75p No VAT STUART TAPE RECORDER CIRCUITS Complete stereo record replay and bias system for reel to reel recorders These circuits will give studio quality with a good tape deck Separate sections for record and replay give optimum performance and allow a third head monitoring sys tem to be used where the deck has this fitted Standard 250mV input and output levels Full details are in our lists Reprint of Original Articles 1 30 No VAT ALPS FF317U FM FRONT END Beautiful precision made High Quality variabie capacitor tuned FM FrontEnd with Dual gate MosFet The tuning capaci tor also has 2 AM Gangs and built in 3 1 reduction gear Covers full FM range of 87 to 109MHz Supply needed is 12V at only 30mA Max Inputs are provided for AGC and AFC signals These have recently
324. ning to the day of classical mechanics and theaether On the other hand some have raised more fruitful suggestions concerning the physical basis of the relativistic or e m Doppler shift Surely at this stage in the career of that theory it should be evident that the theory suffers from a number of definite shortcomings a it is physically incomplete i e certainly questions of physics are still left open by the theory itself and b as basically a correction factor to classical electrodynamics it suffers from a instrumentalist interpretation that prevents these fruitful physical questions from being asked i e the theory concerns rigid rods and clocks but does not directly have a microbasis Assuming that there is some validity in these observations on the theory the following questions seem to be quite open What is the physical basis for the constancy of light s velocity if there is relative motion between source and the observer especially since the classical physics requires that velocity to vary What is the physical basis for clocks or any process running slowerv the inertial 76 system of which it is a part is in relative motion How is the special theory related physically to quantum mechanics Does the paradox of the twins that age at different rates depend more on relative acceleration than on relative velocity Is the special theory valid for systems in instantaneous velocity rat
325. nly with difficulty or signals intelligence would not have retained its importance But the idea that almost all diplomatic traffic can be read immediately on receipt can serve only to encourage the Libyans who know whether they sent such a message and other countries to change to more secure ciphers The leak furthermore served no useful purpose WPC Fletcher was already dead If NSA or GCHQare able to decipher such messages virtually without dealy it may indeed have been blame worthy that a warning did not reach the Metropolitan Police before the shooting But finding a scapegoat is a doubtful advantage ifin the process a source is blown Diplomatic radio communications form one of the fixed services not entirely transferred to satellite A stroll though Belgravia or other embassy districts of London reveals many h f aerials ranging from very large log periodics to the barely visible compact transmitting loop aerial on the roof of the US embassy in Grosvenor Square Diplomatic communicatons remain an important market for h f equipment Foreign embassies however do not have an automatic right to set up radio links Paragraph 1 of Article 27 of the Vienna Convention on Diplomatic Relations 1961 reads receiving state shall permit and protect free communication on the part of the mission for all official purposes In communicating with the Government and the other missions and consulates of the sending St
326. nsformers to speakers Speaker matching transformers all powers Column Loudspeaker trans formers 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 ANC EVEN SINGLE TRANSFORMERS Many standard tyres are in stock and normal despatch times are short and sensible OUR CLIENTS COVER A LARGE NUMBER OF BROAD CASTING AUTHORITIES MIXING DESK MANUFAC TURERS RECORDING STUDIOS HI FI ENTHU SIASTS BAND GROUPS AND PUBLIC ADDRESS FIRMS Export is a speciality and we have overseas clients in the COMMONWEALTH EEC USA MIDDLE EAST etc Send for our questionnaire which when completed enables us to post quotatians by return E A Sowter Ltd Manufacturers and Designers E A SOWTER LTD Established 1941 Reg No England 303990 The Boat Yard Cullingham Road Ipswich IP1 Suffoik P O Box 36 Ipswich IP1 2EL Ergland Phone 0473 52794 amp 0473 219390 Telex 987703G SOWTER CIRCLE 47 FOR FURTHER DETAILS JAPANESE TR D 5m YELLOW 0 10 LED 5mm GREEN 010 BRIOGE RECTIFIERS 0 16 5 MEMORIE 21 sss VOLTAGE REGULATORS 18 0 35 Bas ELECTROLYTIC 47000 16 rrrrrzzrzrccr AN 020 TRIPLERS P1195 2 ORPI2 60 ORPS 820088 R20108 5 5560 BLU ee Please add 50 P amp P and at 15 Govt Colleges et
327. nt drum speed The visible part of the picture is thus _ compressed into a shorter part of the field period and the interval where the head is between tracks rate change of0 1 A direct will be extended Owing to the horizontal alignment condition this extension will be 3 off tape lines at 2X as there is 4 one track jump at every drum revolu tion There are normally 312 lines in a field but at 2 speed an extra 3 can be fitted into the same field period This holds the key to a much simpler way of cal culating the line period which is 64 X 312 5 312 5 3 5 03 298 This can easily be generalised if the specific speed 5 is unity at normal speed H 312 5 S 1 3 5 This equation is to be preferred since no approximation has been made and no knowledge of drum dimensions or tape format is needed except the size of the video offset of It is very easy to arrive at the equation for other standards For example in 525 60 NTSC C format the video off set is 23H The equation follows from that Table 1 shows the effect of applying a variety of speeds to the equation Interes tingly in reverse the field tracks are stretched in time the back wards head jumps lose for each track jumped and the verti cal interval is encroached upon The change head tape speed also changes the apparent frequency range of the f m car rier and consequently the levels and amplitude of the
328. ntal system is compatible with the widest possible range of domestic receivers In May test transmis sions were made of a television programme with stereophonic sound using the experimental system described The results of both series of tests are very encouraging the BBC is pres ently having discussions with the IBA and the receiver industry to establish an agreed UK Standard ence between the main sound carrier and the added digitally modulated carrier Also because of the more noise like nature of a digital signal the visibility of any interference patterns is reduced further which enables the main sound carrier to be maintained at or near its full level avoiding the increased buzz on sound prob lem found with the analogue two carrier system A thorough investigation of the digital option carried out at the Research Department led to over air tests of an experimental system conducted outside nor mal broadcasting hours from the BBC2 transmitter at Wenvoe in South Wales and its associated rebroadcast relay stations during the autumn of 1983 ref 1 This particular area was chosen because the terrain is hilly and multipath propagation of normal television signals very evident The area contains a large concen tration of rebroadcast relay stations which enabled assess ment of the digital sound signal when subjected to the cumulative effects of distortions in a long chain of such stations This article discusses
329. ntarily while files are being saved to cassette or disc it may be best to fix RTS permanently on in the modem This can be done by linking pins 13 and 14 of IC it may then be wise to cut the track between pin 13 and the 25 way socket to avoid contention when the full RS232 interface is used The third position of 5 allows the modem to auto answer calls from other computers This facil ity is allowed only in the 300 baud answer modes and in V 23 mode with S set to reverse Acquisition of a carrier in the back channel is indicated by LED and in the main channel by LED LED lights when the cir cuit is powered and flickers dur ing transmission of outgoing data When a call is auto answered LED lights and LED comes on when the modem is holding a line To test the modem off line set S to the test position The modem should then echo charac ters typed at the keyboard back to the screen Note that this test may not work in the V 23 mode since the Viewdata terminal soft ware will set the RS232 driver and receiver to different data rates Some databases to try The following bulletin board sys tems are run by private individ uals on a voluntary basis No charges are made for use of their facilities which include message handling software downloading and news Forum 80 systems use seven bit word with even parity and one stop bit others have an eight bit word with one stop bit and no parity bit
330. ock an i o mapped v d u in serial form which restricts the charac ter rate to about 1000 s Proces sor i o operations not so ious or fast as memory ones making something of a bottle neck of the i o channel however the possible division of process ing between the main c p u and the v d u circuits can lead to a reasonably fast system Also as v d u memory only has one con troller it can be dynamic without any problems arising It should now be apparent that there are pros and con s to both methods There are further rea sons affecting the choice Word star a popular word processing program is an example of soft ware which can work well with either system but which shows off its best features when modified for use with a memory mapped v d u My solution is to use both systems a memory mapped display for monochrome charac ters and medium resolution gra phics and an i o system for high resolution colour graphics This prompts use of two monitors a john Adams is currently working on the high resolution colour system which we plan to describe in a future article Ed monochrome one for dense char acter display where typically close up use renders a colour monitor tiresome to read unless perfectly adjusted and a full colour output with the option of character formation Controllers The Hitatchi HD6845S used in this design until recently num bered HD46505S is a developed
331. ode in this case to suppress the tv video sig nal in computer monitor mode In the 3845 a resistor is also con nected to this switch and to the junction of the height con trol and R which looking at the back of the set is the leftmost terminal of the height control This allows automatic adjust ment of picture height to the opti mum for tv and computer The video signal is brought in on a short length of screened cable and buffered by a 2N2369A transistor before being applied to the tube grid All connections are made through the tube socket the prototypes being about lin square pieces of Veroboard 66 mounted directly on the back of the tube socket This is the recommended position as long wires will ruin the video quality When making this interface remove the tube socket from the tube while soldering and use stiff wire to mount the interface board onto the socket and flexible wire including the screened wire to link from it to the switch etc in order not to put strain on the socket and c r t neck Most port able sets have the 3845 type of circuit where the cathode is driven and the grid is at zero volts If neither the grid nor cathode is at a low potential then some form of level shifting must be used or better a different type OEA 0 OEC F OFO OFt OF2 OF3 OF4 OF5 OF6 OF7 OF8 9 OFD OFE OFF 000 001 002 003 004 005 006 007 Wire links from gr
332. of Ethernet uses a central passive star cou pler to enable 16 users to com lt Skm Secondary links lt 500m Fig 4 British Telecom s proposed multi star wideband network will use fibre optics in all but the short final link to the customer Fig 5 Ethernet style local area network uses a bi directional data highway approach compared to the enclosed path of a Cambridge ring lan Station Transceiver Ethernet LAN Station Cambridge ring LAN WWww americanradiohistorv com Fi y 57 Locomotive generator and synchronizer OPTICAL FIBRES Outward bound optical highway R Receive Fig 6 D Net optical lan combines a data highway and star return making it more like an open ring References 1 J E Midwinter First generation trunk transmission systems capabilities and limitations IEEE Journal on selected areas Communications vol SAC 1 1983 pp 381 6 2 E Iwahashi Trends in long wavelength single mode transmission systems and demonstrations in Japan IEEE Journal of Quantum Electronics vol QE 17 1980 890 6 3 J Fox D I Fordham Wood and D J Ahern Initial experience with the ton Keynes optical fibre cable tv trial IEEE Transactions Communications vol COM 30 1982 4 W Tsend and Chen D Net new scheme for high data rate optical LANs IEEE Journal on selected areas in Communications vol SAC 1 198
333. of a movable membrane from ref lected light is also popular One of the most widespread uses of amplitude detection is the sens ing of a Gray code from an encoded disc or shutter with res olutions available down to 10 Finally modulated microbending loss can be used by clamping a fibre between two plates with a periodic mechanical grating In general amplitude detection methods are less sensitive than phase modulated sensors and in addition suffer from unwanted and variable signal attenuation and temperature problems ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com DOUBLE SIDED 3 DISCDRIVE ATA SINGULAR PRICE For only 229 95 and that includes VAT and all the necessary leads you can have an OPUS 500k double sided disc drive And remember 2 disc drives are fast becoming the standard for home and business use This is an even bigger bargain than it sounds For vou re getting a double sided drive at the price that other company s sell single sided drives for It reads and writes to the disc cartridge from both sides giving you twice the on line capability of other 3 drives And theres no need to flip the disc over STATE OF THE ART TECHNOLOGY FEATURING e Easy i0 connect to the BBC Micro Double sided e Compatible with most other makes e One touch cartridge load e Comprehensive manual e 3 ms access time e Free disc cartridge e Portable compact and reliable e Format v
334. of the 4 7kQ resistor and 3 3kQ resis tors produces the required d c bias on pins 2 amp 3 via 3 3kQ series resistors The audio input may be to either of these two inputs via a suitable decoupling capacitor As the lowest audio signal frequency is not less than 9kHz the decoupling capacitor may have a conveniently low value of 22nF The components that deter mine the free running frequency of the v c o of the 565 i c which should be the centre frequency of 10kHz are the resistor pin 8 a 6 8kQ resistor in series with a 5kQ variable and the capacitor on pin 9 The values chosen are the same as those for the v c o of Fig 6 except that the resistor is made adjustable For a 10 fre quency deviation the amplitude of the audio input signal can vary from 10mV to 1V r m s and still maintain good tracking of the input frequency The volume setting of the record playback electronics on playback of the recorded signal is thus non criti cal and a mid way setting of CASSETTE RECORDER 100mV r m s ideal The expected direct voltage variation on the output of pin 7 for an input signal with frequency deviation of 10 15 as men tioned earlier about 430mV This can be adjusted to 215mV about the reference voltage level on pin 6 by adjusting the value of the 5kQ variable resistor This is most easily achieved by connect ing the output of the modulator to the input of the demodulator and applying logic low and h
335. of the tree The inner con ductor of the BNC connector EMRI 506 projecting around 3mm was pierced through first into the trunk and then at the end point of the stem supporting the green leaf of the tree Fig 1 The maximum signal tapping point was found after many trials from which we found that the piercing end of the inner conduc tor should touch the moist wet portions of the tree xylem phloem chloren chyma etc The other end of the coaxial cable was connected to a Sony portable receiver model CVM 111E The BNC connector is not necessary to tap the r f energy Fig 2 A bare sharpened inner conductor end of RG 58A U cable itself should be used in practice to economically receive television signals Observations The signal received with the probe antenna alone at the height of the tapping point was very hazy unreadable at 12km distance and practically identification of the picture wasn t possible Fig 3 Further signal was received by the probe alone at 25km dis tance The signals received from the papaya tree trunk its one green leaf and the dipole antenna at 12km and 25km distance were of good readable quality The v s w r under best conditions of reception was around 1 5 Only the leaves pointing clearly toward the tv transmitting tower without obstruction received good televi sion pictures To achieve higher gain better s n ratio of the received tv picture standard antenna ar
336. ohistorv com After a post doctoral fellowship at Manchester University and a yearteaching in Baghdad Brett Wilson returned to Manchester 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 is now back in Manchester this time at UMIST His Ph D wasona high speed laser stroboscope for magnetic bubble research Fig 1 Principal components of optical communications system 55 E x gt ta uw RE Fig 2 Longer wavelength laser systems offer the best combination of repeater spacing and data rate but shorter wavelength l e d systems are less costly 10 100 BIT RATE Mbit s 1000 Fig 3 Tree and branch topology is best suited to broadband broadcast distribution in contrast to the star configuration which permits much easier installation of up stream Star topology selection signalling OPTICAL FIBRES Most of the cables are installed in existing ducts where their small size is a great advantage in an already crowded environment Lengths of around 1km of optical cable are usually pulled through the ducts before being jointed using V groove or arc fusion techniques For second generation sys tems effort is being concent
337. omatically loads and configures the operating system to the MICROBOX hardware requirements The on board ram and eprom discs are seen by the operating system as conventional disc drives The ram disc has the capacity of a 40 track single density disc but with an access time 10 times that of a floppy disc Eprom discs are supported by way of a Send cheque to Micro Concepts CIRCLE 30 FOR FURTHER DETAILS ELECTROVALUE The Wings Appeal Fund helps to maintain the RAF Association Home for Disabled and Chronic Sick Care is essential for those who have served their country and who are inneed So please help by giving all you can foran emblem in WINGS WEEK in September or send a donation to show that you care To Royal Air Forces Association Appeals Dept DS Porand Rd Worcs WR14 2TA _ lenclose a donation of for the Wings Appeal Fund plug in eprom carrier which has provision for four 8 16 32 or 64K eproms into which can be programmed the operating system and any other often used programs by way of the built in programmer MICROBOX can each be allocated as floppy ram or eprom types so providing if required a completely silicon configuration FLEX supports up to four disc drives which in A startup kit for the advanced MICROBOX system is available and consists of Bare PCBs 8K system support monitor FLEX system support disc constructional notes
338. ominal service area limits for BandIV and V transmis sions The system is more rugged than either colour television pic tures or teletext with regard to multipath propagation effects ghosting In March with Home Office agreement the BEC conducted similar tests from the BBC2 transmitter at Crystal Palace to Background to BBC experiments For many years there has been interest in the possibility of add ing stereophonic sound to exist ing television services and the BBC has investigated a number of possible methods In all cases an additional sound signal 5 required to carry the stereo infor mation and in some cases the additional signal is suitable for the transmission of two inde pendent sound signals as may be required for example to provide a bilingual service Methods investigated include the pilot tone system as used for stereo radio broadcasting in the UK the Japanese f m f m system and the German two carrier system all of which employ an analogue second sound signal and digital sound similar to that proposed for direct broadcasting by satellite television The first two methods have certain limitations in this context and were not pursued as serious contenders The German method WW November 1981 Page 40 in use on a limited basis in that country appeared more promising and engineers at the BBC Research Department devised a variant of this method adapted to the PAL System I as used in the UK T
339. omponents Buyers Guide Jan 1985 Dec 19th Single Board Computers Mar 1985 Feb 16th IEEE Instruments 1985 April 19th Power Supplies July 1985 2151 VDU s Sept 1985 Aug 16th Communication Receivers For details regarding advertising Contact Bob Nibbs 01 661 3130 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com TRANSCEIVER SURVEYS Two metre transceivers A survey of amateur radio equipment for the popular 144 146MHz band For most newly licensed radio amateurs the two metre band is a natural starting point It is the lowest band available to those without proficiency in morse code It is also the most popu lous there are no worries about finding other stations to talk to Most equipment now in use on 2m is factory built almost invar iably in the Far East and a wide choice is available with prices starting at a little over 100 But it is still possible for the construc tor to get on the air with a home built rig at a cost of perhaps a few tens of pounds The average choice is likely to be a narrow band f m set for use mainly in the channelized region above 145MHz This type of rig closely resembles the sort of c b set from which many new licensees have recently graduated the con trols are few and simple and operation involves little more than pushing the button and talk ing For this reason experienced operators of
340. on multiple cir cuits and complete master slave backup NEW OPTIONS A continuously expanding range of fully integrated software and hardware is available for both series of Radiocode Clock equipment Standard op tions now include IRIG B precision serial RS232 V24 1mS resolution General purpose parallel o p FSK record replay system Keypad entry of alarm times Calibrated systems for Keypad entry of time date increased accurac Radiocode Clocks Ltd Unit 19 Parkengue Kernick Road Industrial Estate Penryn Falmouth Cornwall Tel Falmouth 0326 76007 Circuit Services Associate Time code generators Intelligent slave systems Standard frequency outputs Stopclock operation CIRCLE 45 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 1 WWW americanradiohistorv com ELECTRONICS amp Wireless Wor over 70 years in ind pendent electronics publishing J July 1984 SEP 9 1984 Volume 90 number 1582 Digital stereophony Television reception Multi standard modem with television with papayatree by Richard Lambley by E H Hartwell antenna Third and final article Tests on digital four phase details the line interface Del ro of by S P Kosta et al plus software suggestions 227 Novel technique couples r f and some telephone transmitting adaitional energy from vegetation numbers to ty stereophone
341. on about amateur radio the RSGB and its publications All publications sold by the RSGB are available at dis counted prices to members RSGB Publications Cranborne Road Potters Bar Hertfordshire 6 3JW CIRCLE 39 FOR FURTHER DETAILS 70 This little devil can This must be the smallest 2M FM mobile available today measuring only 38mm H x 144mm W x 177mm D It has all the features that you probably require included in this microprocessor controlled unit In addition if you feel lonely and can t find anybody on the band just press speech and the optional built in Speech synthesizer will tell you the frequency you are tuned to This is a boon to the blind operator or to those that tuck their rigs out of sight Brief features 25 1 Watt output green LED readout scanning memories and programmable limit band scan priority scan programmable duplex splits 25 and 5 Khz v tuning steps 10 memory channels with lithium back up cell normal and reverse repeater switch dual VFO internal The World System speaker and optional speech synthesizer Just ask for a leaflet and we ll be glad to send you one Thanet Electronics Limited 143 Reculver Road Herne Bay Kent England 1e1 O2273 63859 63850 Telex 965179 CIRCLE 38 FOR FURTHER DETAILS Wireless world EDITORIAL FEATURES 1984 ISSUE PUBLICATION DATE DATE FEATURE Sep 1984 Aug 15th Digital Multi meters Dec 1984 Nov 21st C
342. one 0752 332961 Telex 42513 NMC2732 532 NMC27C32 CIRCLE 903 FOR FURTHER INFORMATION WWW americanradiohistorv com
343. ontact us by telephone and we will send you a form or write to us with full c v and an indication of your salary requirements Telephone CHERTSEY 62671 Personnel Department KentIndustrial Measurement Limited Hanworth Lane Chertsey Surrey Electronics Engineers 49561 Communications Design in High Tech Country ELECTRONICS amp WIRELESS WORLD JULY 1984 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 Medical Elec tronics and we re here to serve your interests Call us now for posts in Design Test Sales or Field Service at all levels from 6 000 16 000 Technomark Engineering amp Technical Recruitment 11 Westbourne Grove London W2 Tel 01 229 9239 Appointments THE EUROPEAN MOLECULAR BIOLOGY LABORATORY AResearch Institute Situated in Heidleberg West Germany INVITES APPLICATIONS FOR THE FOLLOWING POST SYSTEMS INTEGRATOR The successful candidate will be responsible forthe conception and implementation of Microcomputer Hardware and Software for usein various projects with the Laboratory such as on line Image Processing and Graphic Display Systems Systems already in use in the laboratory are based on 280 and M68000 processors in the VME standard configuration A knowledge of these systems is
344. opgate Street LEEDS LS1 4BB 0532 43564 CIRCLE 67 FOR FURTHER DETAILS anh ns 82 ELECTRONICS amp WIRELESS WORLD JULY 1984 Www americanradiohistorv com AWARD WINNING TAPE STREAMER Using standard 0 5in computer tape the 9800 tape streamer from Thorn EMI Datatech may be used as archival back up for hard disc data and for transferring data from mini to mainframe computers The 9800 while taking a standard reel of tape is amazingly small and the combination of electronic mechanical and software design combined with its ergonomic and aesthetic appeal has won for it a Design Council award The combination of hard disc and tape has become established in main frame computer usage for some time With many peripherals and minicomputers however there has been a lot of reliance on floppy or hard discs and a system failure can lead to the loss of valuable data The use NEW PRODUCTS of a back up or archival tape can overcome the vulnerability of such a system Datatech recognised a need for a high speed high capacity desk top tape store which was comparatively low in cost hence the development of the 9800 Compatible with any computer system the machine can automatically lace the tape through the tape path and onto the take up hub The tape cannot be put in the wrong way round the machine will refuse to accept it and signal an error Internally all circuits are on plug in cards and there ar
345. or ANS one item to include in our ads we are packing all these items into the BARGAIN PARCEL OF A ram cara 499 00 modes Switchable CCITT or BELL 103 amp LIFETIME Thousands of components at giveaway prices Guaranteed 10 be worth LAX34 AL LA34 tractor teed 85 00 202 Housed in ABS case size only 2 5 x 8 5 atleast 3 mes what you pay Unbeatable value Sold by weight 1000 s of EX STOCK spares for DEC 9 2286 00 2 5 4 25 pp 1 25 5kls 5 90 1 80 gt 24 11 15 8 periperhals For further data details on other EX STOCK 10615 10 25 225 20 kis 17 50 475 ty all modems 10 00 PRICES PLUS VAT A All prices quoted are for U K Mainland paid cash with order in Pounds Stirling PLUS VAT Minimum order vaiue 2 00 Minimum Credit 10 00 Minimum BONA F IDE account 5 Governmentdepts Schools Universities and established companies Call for details All types of Computer equipment and spares wanted for prompt CASH PAYMENT isc 20 00 Where post and packing not indicated please ADD 1 00 VAT Warehouse open Mon Fri 9 30 5 30 Sat 10 15 5 30 We reserve the right to change prices and specifications without notice Trade Bulk and Export enquiries welcome El Ji c _ 32 Biggin Way Upper Norwood London SE19 3XF LECT 01 679 4414 27924
346. or local technicians in the maintenance of stu dio equipment and mainly small short and medium wave transmitters and aerials Applicants should be familiar with the operation and repair of studio equipment and small transmitters and must be able to advise and instruct people with non technical backgrounds in these skills The postis initially for three years ona basic salary Because of extensive travel itis unlikely to suit applicants with families provides Spanish language training pre departure orientation including instruction in teacing methods insurance air fares and various allowances For a job description and application form please senda brief c v to Overseas Programme 22 Coleman Fields London N1 7AF quoting ref ww The Catholic Institute for international Relations operates a secular over seas programme and is a memberof the British Volunteer Programme 2614 ELECTRONICS TECHNICIAN required for expanding South London company in the amusement industry Applicants are expected to have the appropriate qualifications minimum HNC and have experience of electronic engineering The work is interesting and varied involving repairs fault finding and some research and development Salary scale 18 currently 8 400 9 000 per annum Applications giving full details of age qualifications and experience WWW americanracdiohistorv com 93 Appointments ee mm mm
347. ould be the problem Fitting one of our replacement heads could restore performance to better than new Standard mountings make fitting easy and our 1 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 see The following is a list of our most popular heads all are suitable for use on Dolby machines and are ex stock 20 Stereo Head This is the standard head fitted as orginal equipment on most decks 5 11 90 High Beta Permalloy Head hard wearing higher per formance head with metal capability 8 06 HS16 Sendust Alloy Super Head the best head we can find Longer life than Permalloy higher output than Ferrite fantastic frequency response 9 91 HQ551 4 Track Head for auto reverse or quadrophonic use Full specification record and playback head 9 73 Piease consult our list for technical data on these and other Special Purpose Heads 481 Latest version Double Mono 2 2 Record Play head Replaces R484 8 90 SM166 Standard Mounting 2 2 Erase head Compatible with above orHQ551 4 Track head 5 90 ME151 Non StandardMounting2 2Erasehead 4 25 H524 Standard Erase Head Semi double gap high effi ciency 1 50 H561 Metal Tape Erase Head Ful double gap 4 90 RS7106 Audlo Visual Head 1 2 plus top 1 4 10 82 Tape Head De magnetiser Handy size mains ope
348. ound pin to Select addresses of the i o ports The i o allocation used in the system software is given in Table 1 Links need only be included should these be changed for experimental pur poses If this is not envisaged they may be left out altogether Parallel i o is catered for by uncommitted eight bit input and eight bit output ports a control port used for keyboard input and output to the disc drives and sys tem There is an option for the eight bit parallel output port Use 7415273 and make link 202 for a standard eight bit of set considered Normal settings for are off off on on mapping the v d u at hexadecimal addresses 0800 09FFF switched in by VDUSEL being high Other permutations are possible for experimentation SC84 s disc operating system SciDOS with utility software costs 36 extended Basic with graphics is 22 50 and Basic with enhanced file manipula tion i o control numeric con stant string handling and 12 digit precision is 31 50 These prices include v a t and postage and become 24 15 Disc controller track register Disc controller sector register Disc controller data register Notused STI indirect register STI parallel i o port STlinterrupt pending register B STI interrupt pending register A STlinterrupt inservice register B STlinterrupt inservice register A STlinterrupt mask register B STI interrupt mask register STI pointer vector register
349. oward the end of 1982 the BBC conducted over air compa tibility tests of this variant from the BBC transmitter at Crystal Palace outside normal broadcast ing hours The tests indicated that the system was only margi nally compatible interference between the additional sound car rier and the main sound carrier gave rise to picture patterning which to avoid required reduc tion of the main sound carrier However reduction of the main sound carier to 13dB below the vision carrier as in Germany caused increased buzz on sound in some existing receivers During the period that various options for analogue stereo sound with television were being assessed the status of digital techniques in domestic equip ment had changed considerably and consumer products such as the digital audio disc with its attendant high quality sound had become available Also the BBC proposes using an internationally agreed system of digitally coded sound for d b s These advances led to the consideration of a dig itally modulated second sound carrier to convey the stereo sig nal A digitally coded signal is more rugged than its analogue counterpart and may therefore be transmitted at a lower level This reduces the level of any interfer ELECTRONICS amp WIRELESS WORLD JULY 1984 Vision corrier frequency Main sound carrier centre frequency Proposed Second sound corrier frequency confirm that the experime
350. pa Scarborough both onJuly 29 Pat Hawker G3VA 9 TOROIDAL TRANSFORMERS PDA 7 DAYS DELIVERY FOR SMALL QUANTITIES Secondary Primary V A V ii MSIE US 3v 30v 0 120 3v 30v 0 120 m 3v 30v 80 3v 30v 0 120 725 120 3v 30v 0 120 8 00 160 3v 30v 0 120 900 225 30 0 120 1 a 300 3 30 0 120 13 50 _ 500 3v 30v 0 120 19 00 4 625 3v30v 0 120 2400 1 Prototype Sample Service Available For Special Requirements With Short Lead Time For Production 2 Quantity Prices Available On Application 3 Mail Order CHEQUES TO WYE WINDING CO ACCESS CARD WELCOME We also manufacture to customer requirements laminated transformers R F chokes 1 Inductors and current transformers CIRCLE 43 FOR FURTHER DETAILS WYE WINDING Co CHESTERFIELD ENGLAND Tel Chesterfield 0246 70297 8 9 Telex 54284 10 27 STATION RD BRIMINGTON 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 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
351. pes 224 50 3 p amp p 8034 PHASE LOCKED SIGNAL SOURCE using low frequency reference crystal Speci RF POWER AMPLIFIERS Tuned to your specified ba a inthe gt range 10 250MHz S pii til ren outputin the range 1 600MHz Output 10mW 10dBm 79 50 2 p amp p TYPE 9105 10 mW input 3 watts output 160 00 10 00 p amp p TYPE 9113 TELEVISION FREQUENCY CONVERTER Changes channels in the range 40 TYPE 9155 3 watts input 30 watts output 240 00 10 00 p amp p 1000 2 242 5 p amp p TYPE 9156 As above with integral mains power supply unit 9056 1500MHz PRESCALER Divides 100 1500MHz 320 00 15 00 p amp p by 69 50 2 p amp p 9106 100 mW input 10 watts output 180 00 10 00 p amp p 9086 FM TRANSMITTER 88 108 2 50 watts RF output 24V supply Complete mod TYPE 9158 10 watts input 80 watts output 320 00 10 p amp p ularsystem 380 20 p amp p TYPE 9157 As above with integral mains power supply unit TYPE 9087 As above with integral mains power supply unit 400 00 15 p amp p 4404 25p amp p x RESEARCH COMMUNICATIONS LTD g st UNIT 3 DANE JOHN WORKS GORDON ROAD CANTERBURY KENT 1 TELEPHONE CANTERBURY 0227 56489 CIRCLE 36 FOR FURTHER DETAILS ston 01 943 LB BE Ring for latest stock informz Used test equipment calibrated to manufacturers original specification 99 Waldegrave
352. position the decimal point Manual range changes can be achieved using the UP or DOWN range push buttons and the HOLD facility is sometimes useful to stop automatic range changes Resolution on volts is 10uV and on current Resistance measurements down to 10 pcssible The dynamic range of the decibel function is 30 to 60 Overload protection is excellent and includes spike protection to 2 5kV Basic d c accuracy is 0 03 The displays are seven segment 0 43 red LEDs of the high efficiency type with range and decimal point being automatically annunciated autozero facility is provided and autopolarity means no lead switching and 10uV 4 digits 28500 counts True r m s up to 20kHz Autoranging or manual range selection Big bright high efficiency LED display 30 to 60dBm function Up to 2 5kV spike protection Diode test facility B C D version available IEEE488 compatible with Omnibus 081 option British design and manufacture by Farnell DETAILS FROM FARNELL INSTRUMENTS LIMITED SANDBECK WETHERBY WEST YORKSHIRE LS22 4DH positive or negative reading clearly indicated The sampling rate is 3 readings per second An overrange condition is indicated by all displays flashing TELEPHONE 0937 61961 TELEX 557294 FARIST G around the 19999 count The manual facility may be used to increase resolution as the DM141 provides up to 28500 counts on overrange CIRCLE 5FORFURTHER DETAILS
353. put to either PAL UHF or RGB GM811 CPU BOARD An industrial standard 4 MHz 280 GM816 MULTI BOARD Provides three Z80A PIO devices controller board with parallel and serial I O together with a plus CTC and battery backed Real Time Clock perce memory papacy GM848 SERIAL I O BOARD Utilises two Z80A SIO chips GM888 CPU BOARD A new card featuring the Intel 8088 providing four synchronous asynchronous serial channels with processor to provide a dual processor system software selectable baud rates GMB32 SVC BOARD Provides conventional 80 x 25 or 40 x 25 GM836 NETWORK INTERFACE BOARD Provides RS422 screen format together with graphics capability Includes full communication protocol for networking CPU boards keyboard support and overseas character sets 862 256K RAM BOARD Supports both page mode and extended addressing facilities and can be used with all of the Gemini CPU cards 833 512K RAM DISK BOARD Provides psuedo disk facility MultiBoard system GMB29 FDC SASI BOARD Combines floppy disk controller and SASI board supports up to four floppy disk drives plus The dea ler s choice Winchester controller cards Gemini Microcomputers Ltd 18 Woodside Road Amersham Bucks England HP6 OBH Tel 02403 28321 Telex 837788 P MULTIBOARD COMPUTERS M ELECTRONICS amp WIRELESS WORLD JULY 1984 43 WWW americanradiohistorv com 44 Multi Standard MODEM AM 791
354. puter input or broadcasts Numbers in circles refer to pins on the cathode ray tube controller socket The tv circuits must be isolated from the mains ves text SPECIAL FEATURE SC84 microcomputer continued from page 34 output is captured in an eight bit latch by the trailing edge of the next carry pulse and held dur ing the next memory cycle This allows the eprom to produce the dot pattern for character zero while character one is being brought from memory The trail ing edge of the next carry pulse occuring 500ns later allows plenty of time for the eprom to submit a dot pattern This pulse enables parallel loading of the shift register used to convert the dot pattern from eprom into a serial stream of pixels Being syn chronous the shift register does not load the dot pattern until the rising edge of the dot clock which occurs while the load input is low This edge occurs just before the end of the carry pulse and might not at first appear to be consist ent with the synchronous philos ophy propounded earlier as there is an undefined delay between this clock edge and ending of the carry pulse Note though that it is this same clocking edge which advances the synchronous coun ter and thus ends the carry pulse which must therefore change after the rising edge of the clock Also the required holding time for the loading signal after shift register clocking is zero and the clocking signal is from a
355. r variable output John also gives some SC84 construction tips 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 5 1 Available on microfilm please contact editor By post current issue 1 30 back issues if available 1 40 order and payments to EEP Sundry 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 545 Telephones Editorial 01 661 3614 Advertising 01 661 3130 See leader page Telex 892084 BISPRS G 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 Quadrant Sutton Surrey 5 2 545 Telephone 01 661 3248 Subscriptions Oakfield House Perrymount Road Haywards heath Sussex RH 16 Telephone 04444 459188 Please notify a change of address USA 549 40 surface 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 Husiness Press International Ltd 1984 ISBN 0043 6062 WWW americanradiohistorv com Editor PHILIP DARRINGTON 01 661 3128 Deputy Editor GEOFFREY SHO
356. r battery operation an accuracy of 4 parts per million 1 count and totally automatic operation all this for only 116 00 with GSC s new Max 100 frequency counter Just take a look at our spec Where else could you find anything similar at the price Frequency range 5Hz 100 MHz Input impedance 1M shunted by 10pF Sensitivity 30mV from 1KHz up to 50MHz 120mV r m s over full frequency range Timebase accuracy 74 parts in 106 from 5 to 45 C Maximum aging rate 10 parts 106 per year Over frequency indication Low battery power alarm Operates from dry or rechargeable cells an external 7 5 to 10VDC supply or a car battery an adaptor Dimensions 45 x 187 x 143mm Options 12V adaptor battery eliminator r f TOMORROW S TOOLS TODAY antenna low loss r f tap carrying case ep rsen ak post Fili in the coupon for further details Goods despatched within 48 hrs summ GENE Gm amm GLOBAL SPECIALTIES CORPORATION G S C UK Limited Dept 7D Unit 1 Shire Hill Industrial Estate Saffron Walden Essex CB11 100 FREQ COUNTER Unit price inc P amp P 15 VAT 136 85 zen al ez 1 Address G S C UK Limited Dept 7D Unit 1 Shire Hill Industrial Estate enclose cheque P O _ E __ Barclaycard Access
357. r resist ance and electrical power in the form of a constant current for the repeater electronics is obtained via a continuously welded copper cylinder jacket The overall diameter of the completed cable will be just over 20mm under half the diameter of the previous copper coaxial TAT 7 cable The underwater repeaters which have not yet been finalised will probably use up to four laser transmitters one actively employed and the other three as standby units This is thought to be necessary because of the limited lifetimes so far achieved with 1 1 45 coupled with the enor mous cost of underwater repairs Optical detection is performed by InGaAs p i n diode rather than ana p d because of complex ity of providing a high voltage supply to an a p d silicon bipo lar transimpedance preamplifier is used in preference to a GaAs unit because as yet silicon fabri cation technology is more proven than that required for GaAs Active waveform retiming is car ried out at each repeater by clock extraction circuitry Various monitoring circuits transmit operational information back to the shore based stations Broadband information services The use of optical fibre technol ogy has been much discussed with respect to the re cabling of Britain where a single unit on the customers premises would provide access to a wide range of tv channels and interactive infor mation service Connections between the customer s unit
358. ral and being there Positioning of the performer becomes 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 ANTENNA TUNER NEW 0 1 30MHZ IMPROVES RECEPTION switched series para llel bandpass adapts to absorption wavemeter field strength meter modulation monitor 25 20 TIME WRONG MSF CLOCK is ALWAYS CORRECT never gains or loses SELF SETTING at switch on 8 digits show Date Hours Minutes and Seconds auto GMT BST and leap year can expand to Years Months Weekday and Milliseconds parallel BCD output for computer audio to record and show time on playback receives Rugby 60KHz atomic time signals only 15X15X8 cm built in antenna 1000Km range GET the TIME RIGHT 72 70 Each fun to build kit ready made to order includes all parts case by return postage etc and list of other kits PROGRAMMABLE WEEKLY TIME SWITCHES TELEVISION SOUND TUNERS Please send me information on Timeswitches Television Tuners Ambisonics i RA dto m ERN CAMBRIDGE KITS 45 WG Old School Lane Mitton Cambridge Tel 860150 Minim Electronics Limited Lent Rise Road Burnham Slough SL1 7NY Tel Burnham 63724 ww7 CIRCLE 68 FOR FURTHER DETAILS 48 ELECTRONICS
359. rated on long haul high speed commu nications where the cost is affected strongly by repeater spacings Hence it is natural to uselaser driven monomode fibres in their minimum dispersion region at 1 3um Repeater spac ings of 20km are typical with data rates of 400Mbit s being employed NTT Japan over routes ultimately several thou sand kilometres in length Most field trials however have been conducted with shorter routes of around 100km The promise of low loss trans mission with high data rates is obviously of great importance in the area of underwater telephone cables In addition the lower weight and smaller size of optical fibres compared to copper coaxial cables is of great economic and handling importance considering the long lengths of cabling approximately 6500km involved in a transatlantic crossing The various agencies concerned have mapped out the nature of the first optical fibre transatlantic tele phone cable TAT 8 to be installed in 1988 It is intended to operate multi ple optical fibre pairs at 280Mbit 5 equivalent to 35 000 two way voice channels with repeater spacings of more than 35km Monomode fibre will be used excited by 1 3um injection laser diodes Strength is provided by the usual arrangement of central and peripheral steel elements with cushioning from interstatial Distribution centre 7 user Tree and branch elastomer and an external pol yethylene coating Wate
360. rated unit prevents build up of residual head magnetisation causing noise on playback 454 Curved Pole Type for inaccessibie heads 4 85 Please add part cost of post packing and insurance as follows INLAND Orders up to 10 50p Orders 10 to 49 1 Orders over 50 1 50 OVERSEAS Please send sufficient to cover Surface or Air Fost as required Add 8 channels to your scope New OM358 multiplexer 169 vat AN Ne 227222222772 The Thurlby 358 gives any oscilloscope an 8 channel display Observing many waveforms simultaneously can be essential when analysing sophisti cated equipment Application areas include microprocessor based products data transmission systems A to D converters frequency synthesizers etc The 358 is ideal for digital equipment it can often solve problems that would otherwise need a fast logic analyser but unlike dedicated logic test instruments it is equally suited to analogue waveforms The OM358 has a bandwidth of 35MHz and 3 calibration accuracy Each input has an impedance of 1MQ 20pF and accepts signals upto 6 An 8 channel 4 channel or single channel display can be selected with triggering from any channel Colour data sheet with full specifications available OM358 with two BNC cables 197 80 inc P amp P and VAT CIRCLE31 FOR FURTHER DETAILS Thurlby Electronics Ltd Thurlby New Road St
361. ray techniques using a few suitably located Papaya trees or a few suitably oriented leaves need to be studied in depth Under average conditions slow breeze and feeble rain the observed tv picture quality was fairly satisfactory Theoretical model To a first order of approximation one may simulate either suitable symmetrical geometrically shaped freshly cut or live vegetation branch or a bunch of branches like fern date palm bottle brush as a standard well known die lectric rod antenna configura tion or papaya coconut type live branch leaf as a thin dielectric sheet aperture antenna The exact constitutive par ameters of a green leaf are not well known Because of the very large static dielectric constant of water one can well expect that the moisture content of the leaf will have a predominating influence A reasonable estimate of the complex dielectric constant of green foliage Du and Peake can be made from the following equa tion CCS Ds gt p Ta i w Ge f lv f where g the ionic conductivity due to dissolved salts of the fluid in the leaf G is the fraction of water content f is 16GHz have the usual meanings and the conductivity of the dissolved salt may vary widely but is assumed here to be 0 2 to 0 4 X 10 Further the effec tive relative dielectric constant of the medium can also be
362. rcome for broadcast quality units and studio cameras may still be some way off Largest exhibit at NAB was mounted by Sony Corporation at a cost of over 1 million They featured their in Betacam integrated camera recorder and a complete high definition system NBC have begun distributing network programmes to 22 affiliate stations via satellite and plan to increase this to 150 stations by early 1985 About 17 million US homes 19 of tv homes now have v c r machines still significantly below UK penetration Amateur Radio Moonbounced TV Andrew Emmerson G8PTH has passed along news from Maurice Clot of what promises to be a remarkable and unique experiment aimed at gaining a world first in amateur television French amateurs are to attempt moonbounce of television signals transmitted on 1255MHz using an aerial with a calculated gain of the order of 90dB To make this possible the French electricity authorities have granted permission for F9CH and F6BGR to use the 10 000 square meter plane metal reflectors of the French experimental solar oven near Fontromue East Pyrenees as an aerial with a dipole element replacing the normal crucible and with the computer programmed to follow the moon instead of the sun It is planned to use frequency modulated vision signals with a transmitter power of 140 watts during tests between July 9 andJuly 13 when the moon will be low enough on t
363. rential phase and gain 4 and 4 max 2 and 2 typi cally Physically it is 2U high full bay width unit Channel setting tun ing is by front panel thumbwheel 0 2 Fig 91 Alternative self contained decoder board Fig 34 amp 36 circuits not used incorporates TDA35614 with the luminance notch filter of Fig 77 and the chroma high pass filter of Fig 81 hard wired at the p c board edges Board also has copper tracks laid out for RGB output stages if needed for video processing improvement similar to that in the TX10 receiver Fig 41 May issue Boards available from WWW americanracdiohistorv com Fig 100 Resulting picture improvement with scan velocity off and on screen photographs taken from a Mullard report switches which control a synthe siser a rear D plug enables remote control Details of the internal operation are shown in Fig 97 the notes on this block diagram explain the functions Other methods of picture enchance ment There are excellent picture enhancers that rely on picture storage and can provide both hori zontal and vertical aperture cor rection By recycling the informa tion taken from the picture store with new pictures as they arrive noise reduction is achieved But on movement zonal adaptive 300 GROUP DELAY ns 0 2 406 8 10 FREQUENCY MHz Fig 95 Group delay response of the high pass chromafilter techniques are needed to stop cu
364. requency of the main sound signal and at an amplitude of between 20 to 25dB below it This is a larger fre quency spacing than that used in the earlier BBC tests on the ana logue two carrier system where a spacing of about 6 3MHz was best because of the greater band width about 700kHz of the dig itally modulated signal compared with that of the f m signal The upper limit on the spacing of the second carrier from the vision carier was determined by adjacent channel interference both from the viewpoint of inter ference from the digitally modu lated signal into the vestigial side band of the upper adjacent chan nel and vice versa Laboratory tests indicate that with the second sound carrier at a level of 20dB below the vision carrier level interference from the digitally modulated second sound carrier into the upper adja cent channel is not a problem and complies with the CCIR recom mended protection ratio In fact the main sound carrier is the limiting factor for interference into the upper adjacent channel this remains true even when the main sound carrier is reduced by 3 to 10dB below the vision car rier Interference from the upper adjacent channel into the digital sound channel seems more likely because the CCIR recommended protection ratio in this direction is much more tolerant Any interference to the digital sound channel from the vestigal sidebands of the upper adjacent channel vision signal is pict
365. res that a logic high level is output from the op amp when no audio signal is present on the input to the demodulator Two outputs are provided from the op amp one at t t l levels suitable for coupling directly to 1 1 1 i c inputs and one at an RS232 type level I must confess at this point that although I have shown the modulator and demodulator cir cuits of Fig 6 and 8 with RS232 type inputs and outputs I have ELECTRONICS amp WIRELESS WORLD JULY 1984 not tried them out on my own computer preferring to use 1 1 1 levels It is my understanding that RS232 type inputs and out puts normally invert the t t l logic levels In so far as I have shown the RS232 type inputs and outputs being used this should not matter since if the modulator is connected to the demodulator then high input on the modula tor will produce a high output from the demodulator However in the absence of an audio signal input to the demodulator thet t 1 output should be high If the RS232 type connection is used on the output of the demodulator this will also be high subse quent RS232 input on the micro computer may invert this to a logic low on its t t type output To invert this logic the 1MQ resistor connected between the negative input of the op amp comparator and the 15 volt sup ply rail should be connected to the 15 volt supply rail instead A final article will describe the up down tape counter and record
366. rine transceiver with all channels and every operating convenience imagin able yet small enough to fit comfortably in your hand incorporating the latest in efficient CMOS components the Mariner 99 goes a step fur ther in prolonging the life of bat teries with its unique power save mode using just one seventh of the power required by common squelched moni toring The multimatch facility is not restricted to the usual by usual we refer to main stations dual or triple watch but will in fact cope with up to 10 chan nels These memories can also be used in conjunction with the priority channel mode For those intrepid explorers who venture across the Atlantic you will be pleased to hear this handheld also copes with all the US channels including the weather channels NOW AVAILABLE AT 245 VAT inc nicads and wall charger DON T FORGET THE SMC 104M 6 channel handheld IS STILL AVAILABLE AT 160 VAT inc nicads and charger E SOUTH MIDLANDS COMMUNICATIONS LTD CSD gt gt OSBORNE ROAD SOUTHAMPTON lt Tel 0703 867333 Thx 477351 SMCOMM G CIRCLE 56 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 28 FOR FURTHER DETAILS IN VIEW OF THE EXTREMELY RAPID CHANGE TAKING PLA
367. ripherals to have access to the full duplex data channel operating at 100Kbit s over a range of one km Interconnection of RS232 interface between adjacent remote sites permits cascading and allows the system to be extended for up to 10km A fibre splicing technique has been incorporated into the system and this is claimed to take one third of the time needed normally to make splices and yet offers a high fidelity connection into each modem The modems are priced at 250 each and saving is claimed from the use of single strand fibres lower in cost than the equivalent twin strand or screened twisted pair cables normally used Easdata Ltd 7 Charleton Rise Welwyn Herts AL6 9RP EWW 217 s 3 MARCONI SIGNAL GENERATORS TF2002A S illustrated 2 272 AM FM 750 9 TF2002 As above but AM only 450 MARCONI TF1066B AM FM Generator 10 470MHz 0 2uV 200mV output FM Deviation up to x 100kHz MARCONI 995 5 AM FM Generator Narrow deviation model 995 covering 1 5 220MHz 450 TF2015 10 520MHz AM FM TF144H AM 10kHz 72MHz 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 ixe 225 RALFE ELECTRONICS 10 CHAPEL STREET LONDON NW1 TEL 01 723 8753 Er eet Mis 1 6MB 8 FLOPPY DISC DRIVES gt gt Sporn New Stock Emi N After our recent sell out of t
368. ronics I set my sights cautiously on a mean frequency of 10kHz i e 9kHz and 11kHz for the low and high frequencies A bit rate of 2400 has a highest frequency content of 1200Hz when a train of succes sive ones and zeros are being transmitted Thus this figure was taken as the highest rate that could be easily be transmitted using the two nominal frequen cies of 9kHz and 11kHz Actu ally by pushing the mean f s k frequency up to 12kHz and careful design of the demodulator stage it should be possible to record at 4800 baud Alternatively it should be possible to drop the mean frequency to 6kHz and still be able to record at 2400 baud F s k modulator amp demodulator circuits The circuits of the f s k modula tor and demodulator are shown in Figs 6and 7 Iclaim nooriginality ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com q 3 by A J Ewins Fig 6 F s k modulator based on Signetics circuits but with triangle to sine converter for greater flexibility in choice of record playback circuitry Fig 8 Internal layout of 565 1 1 Audio Fig 7 F s k demodulator using Signetics 565 phase locked loop 62 CASSETTE RECORDER for these being but a variation of circuits published by Signetics in their book on the 566 v c o and 565 1 1 integrated circuits To the circuit of the modulator I added a triangular to sine wave form convert
369. s sion periods alternating with three minutes of listening the life expectancy of a battery pack is likely to be in the region of two and a half hours The current drain in the stand by condition is a detail worth seeking out on the manufac turers data sheet Some of the early portables had led displays which were so heavy on current that they had to be blanked for much of the time But if the user anticipates long periods of inten sive operation it is worth looking for a model with a quick change battery pack so that a spare can be slipped in when the output starts to droop With certain sets the manufacturers offer a choice of packs in different sizes some of them having a higher than usual nominal voltage to give increased transmit power The receiver Receivers too have their share of design improvements Ceramic filters offer excellent filtering at low cost and new low noise r f devices are bringing enhanced performance in the front end Beginning to make an appearance in commercial two metre equip ment is the gallium arsenide fet But it is worth bearing in mind that fashionable components do not automatically make a set bet ter Receiver sensitivity usually features prominently in radio manufacturers promotional material though the figures quoted are not always expessed in the same units and it can be diffi cult to raw meaningful comparis ons However the goodness of a receiver is affected by
370. s BBC Research Department Report 1972 6 7 J Sabatier and F Kretz Sampling the components of 625 Line television signals EBU Review no 171 Oct 1978 8 G D Roeand D C Read Patent 2256 77 Comb Filters for PAL Coders and Decod ers Nov 1977 UK patent 2256 77 9 C K P Clarke 1982 High Quality Decoding for PAL inputs to digital YUV stu tos pi BBC Research Department Report 10 P G 1 Barten and J Kaashoek 30AX Self aligning 110 In line Colour TV Displa Mullard Technical Note 119 PJM Sijbers and J Zeelen Philips Technical One and a SAW filter in a high vision i f channel Elec tronic Components and Applications vol 5 1 Nov 1982 12 A Oliphant 1982 Weston Clean PAL BBO Research Department Report Fine adjustment 4144 0605 Switching voltage 0 90 180 270 5 Threshold Switch Fig 98 Block diagram describing a method of scan velocity modulation to improve picture sharpness Luminance transition Signal entering limiter Deflection field in tube neck Resulting transition enhancement at picture tube Spectral energy inthe transition but due to band width and RGB drive slew rate limitations this does not reach the tube face AMPLITUDE 21035 MHz LY Suitable section of spectrum to operate scan velocity mod Fig 99 Example of waveforms occurring in a scan velocity modulation circuit Fig 101 Functional block diagram of an availab
371. s These problems specifically of VHF Signal Generator 25 to 480MHZ Marconi Electronic size and thermal efficiency became particularly aggravated at high powers and SLSV 185 00 TF2604 125 00 considerably lengthened OEM product development Marconi Displays TF 2212 100 00 Sweep Signal Generator 400 to 1200 MHZ By including thermal design in the totality of board design it has been possible to SWU 225 00 reduce the size of the electronics and increase the efficiency of the transistor to UHF Signal Generator 300 to 1 000 MHZ Marconi XY Displays 2213 1t 25010 heatsink thermal circuit The combined effect of this has been to dramatically SDR 145 00 HEWLETT PACKARD PSU increase the volumetric efficiency of the amplifier heatsink assembly The SYSTEM UHF Test Receivers 280 to 4600 MHZ 6433B Power Supply 0 36v 10A 195 00 Amp offers 1 2kW of power in a space of 180mm x 102mm x 77mm excluding PSU USVD 175 00 6448 Power Supply 0 600v 1 5 195 00 and Fan Selentomat Type USWV 225 00 6453 Power Supply 0 15v 200A 275 00 The basis of this considerable advance is the PANTECH 74 Heat Exchanger designed and manutactured by us By eliminating the laminar air flow found in Stereodecoder Standard MSDC 225 00 Bradley Pulse Generator 1768 195 00 UHF Power Signal Generator SCRD275to CCTV Video Cameras 2 3 Vidicon 75 00 conventional extruded heatsinks heat transfer to the environment is greatly 2750 MHZ 05 to 50 watts 400 00
372. s available subject to approved references Add 1 00 to order under 50 value prices are excluding VAT please add 15 to order and postage GUARANTEE goods to specification and sold with manufacturers warranty CIRCLE 66 FOR FURTHER DETAILS WWW americanradiohistorv com ELECTRONICS amp WIRELESS WORLD JULY 1984 DIGITAL AUDIO Digital stereophony with television Tests on digital four phase d p s k technique of transmitting additional sound information for tv stereophoney show the system to be more rugged than for either teletext or colour television pictures A single high quality broadcast audio channel requires a band width of at least 15kHz Simple linear quantization of an audio signal requires at least 13 bits per sample for acceptable broadcast quality Near instantaneous digi tal companding however enables the number of transmit ted bits per sample to be reduced to ten with negligible degradation in quality Assuming a 15kHz audio bandwidth a sampling rate of about 32kHz is required to satisfy the Nyquist criterion and thus avoid unwanted alias effects The minimum bit rate for a single high quality audio channel is therefore about 320kbit s To this must be added the bit rate needed to transmit additional data such as framing words parity bits for error detec tion and the scale factor words associated with near instantane ous companding Two such chan nels therefore require
373. s 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 Isolated video driver Designed for connecting computer video output to a non isolated domestic tv this circuit uses a readily available 6N139 optical coupler RS Components operating at 1 1 current transfer ratio Positive video modulation is assumed and for the UK a composite video signal bandwidth requirement of 6MHz Voltage gain of the fet stage is about four The source is directly coupled to the next stage which approximates a current drive for the coupler led Bias current of around 9mA determined by the fet drain source resistors and supply voltage keeps the optical coupler transfer characteristic in its linear region Capacitor C negates the effect of Miller capacitance in the driver transistor and C extends frequency response to above about 800kHz by quickly removing stored charge in the transistor emitter during voltage transitions Resistor R is set for optimum rise and fall times Collector current in the opto coupler is about 7mA allowing low resistor values to be used to shunt Miller capacitance ELECTRONICS amp WIRELESS WORLD JULY 1984 so that the transistors can operate a
374. s of gulmohr canna bottle brush coconut date palm fern etc as electromagnetic antennae struc tures at microwave frequencies These studies reveal that certain geometrically shaped vegeta tion dueto water and chlorophyll content vis a vis their dynamic complex dielectric properties can sustain propagate and radiate electromagnetic waves from their structure if suitably excited A gain varying from 2 to 5dB over an exciter probe antenna from selected vegetation canopies at 1000 3000 and 4000MHz has been achieved with satisfactory impedance matching character istics The radiation pattern of the exciter probe antenna be shaped with increased its gain axially when it excited an e m wave on vegetation cover struc ture range of branches from a single tree branch to a bunch of a few branches kept in a plastics cone to maintain a dielectric rod antenna configuration of the bunch were used to achieve bet ter radiation pattern characteris tics with a gain of around 5dB over that of the exciter probe antenna In all these studies a probe helix at the end of a vegetation branch was used to excite an e m wave on the vegetation structure The radiation characteristics so observed were found to remain so long as the vegetation structure is fresh and start to deteriorate with increase in dryness We further reported experi mental studies to receive Band 3 television signals from the Banga lore transmitter radiatin
375. s the compu ter might be processing input R3 Ro 4k7 5 102145104 C1 Q9 1n 22 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com information in real time suggest ing that time should not be wasted by scanning the keyboard unnecessarily These conditions were met dy making the system interrupt driven and bit mapped Ttis means that any change in key board status due to a key being pressed or released produces an interrupt signal causing the com puter to read the status of all the notes on the keyboard On read ing the keyboard the computer stores a bit mapped image zero for an unpressed key one for a pressed key of the current board status for subsequent anal ysis display sound generation etc Hardware A four octave C C 49 note key board is used Initially the 49th note proved a minor nuisance since 48 notes can be neatly mapped into six bytes However in the final design it turned out to be convenient to read the key board in eight bytes so the system can accommodate a five octave keyboard One byte is used to check that spurious noise pulses have not sent the interface byte counter out of step with the read ing software Keyboard and key switches used are those sold by Maplin Electronic Supplies as the basis of their Spectrum Synthesizer nc connection with the well knowr microcomputer The key switches are unusual in that they are simply coiled
376. sceivers operate between 1 6 and 30MHz A small display indicates the selected channel while an audible tone and aflashing light warn the operator of an incoming call Racal Messenger Ltd 5 Bennett Road Reading Berks RG13 EWW 211 WORD PROCESSED TELETEX An adaptor has been devised by BT to provide the Merlin word processor with the facility to connect to teletex services This claims Merlin the business machine branch of British Telecom provides the ability to exchange text information in a rapid error free and cost effective manner Using the de facto standard for electronic mail the system will communicate with any other teletex terminals of any manufacture The system has been developed by BT research engineers and has undergone a series of network user trials prior to its public launch As well as providing teletex protocol the system offers auto dialling auto answer for unattended operation store and forward operation allowing messages to be transmitted at times when the charges are lower automatic logging of all documents sent and received and a full character set ensuring that the copy is received exactly as sent Future expansion will include inter working with telex and packet switched services Merlin don t provide an address all you need dois pick up a telephone dial 100 and ask for Freephone Merlin EWW 212 ELECTRONICS amp WIRELESS WORLD JULY 1984 Polynet local area network
377. slot mini rack with power supply 64kB DRAM supporting monitor ROM CUBE BeebFLEX sideways ROM and TUBE interface Please ask for our new Catalogue which fully describes the CUBE range of 6502 6809 Eurocards Anexplanatory colour Manufacturers of the CUBE Range of Industrial Microcomputer Systems Andersons Court Newnham Road Cambridge CB3 9EZ Tel Cambridge 0223 358757 Telex 995801 GLOTX G From 167 00 ex VAT 328 90 ex VAT CIRCLE 18 FOR FURTHER DETAILS E VA ODIS TRANSDUCER and RECORDER 5 and SYSTEMS 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 05 S 49 51 Fylde Road Preston Laboratories PR12xQ Limited Telephone 0772 57560 CIRCLE 53 FOR FURTHER DETAILS Visual monitoring of anything anywhere by phone in seconds with Robot Phoneline TV Robot s Phoneline TV systems provide a low cost efficient solution to the problem of visually monitoring remote installations meters gauges traffic weather water levels or any subject large or T Phoneline equipment works well with standard equipment and converts the broadband video signal from the camera to narrow band audio tones for transmission via the dial telephone network
378. springs soldered to a p c b at one end and touch ing a bus bar on the p c b at the other end when the key is pressed the p c b is also supplied This seemingly effective keyboard is easy to assemble and much cheaper than using conventional organ key switches Some initial problems were experienced due to key bounce caused by spring vibration but these were solved by inserting lengths of soft foam plastic at the edge of the p c b where the switches are soldered to damp the vibrations The BBC microcomputer user port is connected to the B lines of a 6522 versatile interface adap tor v i a It carries eight data lines D two handshake lines CB a number of ground lines and the computer 5V supply Through programming the v i a can be made to generate an inter rupt signal when CB changes from high to low or alternatively low to high but not both For the keyboard a response is required when any key is pressed or released and even if a number of other keys are already held down so a means producing a suitable interrupt signal is needed Figure 1 shows basic key con nections in which two equal resis tors establish a steady state voltage of 2 5 on the strobe rail Each key switch is conncted to a network made up of and Initially C has a potential differ ence of 2 5V across it lower plate 5V upper plate 2 5V When the switch is closed the lower plate potential falls initially by 5V
379. states for the input bit pair sequence 00 10 11 and 01 are illustrated in c Choice of second sound carrier The relative levels of the vision and sound carriers and the fre quency spacing between the main and second sound carriers have to be chosen to give good compatibility with existing receivers whereby interference to the picture or main sound Table 2 Modulation system for experimental digital stereo sound with terrestrial television 6 55MHz above vision carrier 204 with respect to peak vision carrier 4 phase d p s k at 704kbit s 700kHz 10dB with respect to peak vision carrier channel is kept to a minimum The frequency and level of the second sound carrier must also be chosen so that the digital system works reliably throughout the service area of normal television reception A third requirement is that the second sound carrier must not interfer with transmit ters operating on adjacent televi sion channels The first and third requirements have been investi gated in the laboratory and the second during the field tests in South Wales Inevitably these requirements conflict and a com promise has had to be sought Theory and laboratory tests indicate that to avoid interfer ence to or from the main fre quency modulated sound signal the additional digitally modu lated sound carrier woudl need to be spaces 6 5MHz or more above the vision carier i e 0 5MHz above the rest f
380. step on or Reverse CIRCLE 24 FOR FURTHER DETAILS Trackdown SWITCHMODE power supply Barlec Richfield and SGS have the solution L296 SWITCHING REGULATOR y scostetiecive 222 Short circuit protected 9 Output over voltage m 1 protection Switching frequency 5 1v to 40v output to 200kHz DIDI 4A output current Very high efficiency YY amp Upto160w output sewer p Thermal shutdown eProgrammable current Remote inhibit and limiter sync input amp Soft start oo circuit for crowbar now better served to serve you better amp Reset output For com a plementary evalu T Precise 2 ation kit please write to ep West Sussex RH135PX chip reference Barlec Richfield on your A member of the IBR Electronics Group Very few components company headed paper 4 CIRCLE 10 FOR FURTHER DETAILS 24 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com Television reception with papaya tree antenna Novel technique couples r f energy from vegetation canopy to receive tv signals Back in 1979 we conceived of using green vegetation canopy as an r f antenna and conducted feasibility studies with a live cyp ress plant and freshly cut date palm leaf branch at 1000MHz to successfully demonstrate it Later we conducted experimen tal studies to use vegetation canopy leaves and branche
381. system documentation component supplier list PRICE 95 V A T FLEX disc operating system for MICROBOX including editor and assembler 75 V A T 8 SKILLICORNE MEWS QUEENS ROAD CHELTENHAM GLOUCESTERSHIRE GL50 2NJ Telephone Cheltenham 0242 510525 Out of a very wide ran some of the more popu e of types we show arly demanded ones The full range currently stocked will be found in our latest free A Z price amp products list Please mention this journal when contacting Electrovalue MINIATURE TOGGLES 7000 Series 250V 2A 120 V 5A Single double three and four pole configurations inc Centre Off On and biased CK WAVECHANGE with adjustable stops 1P 12 way 2P 6W 3P 4W 4P 3W_ 6P 2W SWITCH KITS RA Shaft Assemblies up to 6 wafers DP Mains switch Screens Spacers PUSH BUTTON Miniature Single and Double Pole Changeover Standard Latching and momentary SLIDERS Miniature amp Standard SP and DP in 1 2 or 3 positions Many other types such as for timing and other special applications BRITAINS LEADING QUALITY COMPONENT Please tick if receipt required orinformation on RAFA Membership SUPPLIERS SEND FOR FREE 32 PAGE 2 LIST ATTRACTIVE DISCOUNTS FREE POSTAGE GOOB SERVICE amp DELIVERY 28 St Jude s Road ELECTROVALUE LTD 2259 Egham Surrey TW20 OHB Tel 0784 33603 Telex 264475 North 680 Burnage Lane Manchester 061 432 4945 EV Computing Shop 700
382. t which allows the receive frequency to be offset slightly from the transmit fre quency this is to help resolve off channel transmissions On the more expensive multi mode sets there may also be a control to pull the transmitter frequency slightly for satellite working Whth this the operator can comp ensator for Doppler shift as the spacecraft approaches recedes In some of the cheapest sets the hand held portables fre quency selection is by means of a bank of thumbwheel switches This method works well enough if the switches are reliable though some users may prefer to pay a bit more to have a digital display giv ing positive indication of the tuned frequency Many recent portables have a low power liquid crystal display with a calculator WWW americanracdiohistorv com Tr 19715843445 323104 3802 01 pue 820 9 20 Sa npos 29115903045 83104 2911990 40 4123409 PJIN 9531 623 JaztSayQUAS 823104 9105003 01235 n s d Japooua auo 218 1847806 5811408 20 dn 32eq 20 20 j1un sapuedxg GZ yazisayzuds 428906 iun Aeqdstp 041u02 ajoway J1e sayeads die sayeads jayoeaq 811408 1195004 MSZ 620 20 Japuedxj 533ed pjIN dee seauty 399552 ued 2 1008 20
383. t 25 pieces Write or phone for list Please add 50p post amp packing to orders under 15 and VAT to total Access amp Visa welcome 24 hr phone service on 054 422 618 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 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanradiohistorv com mM 10015 z x 4 Philips Fluke s Hameg Full Colour Catalogue Test Equipment Send for your free copy now nee New Generation ortable ultimeter with 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 itself n in the an m invaluable when taking readings in dimly lit areas The PM2518X also offers autoranging 20 199 8X amp current range true RMS measurements Complete with Batteries on voltage current extended 4 digit capability dB relative reference and much Also available without much more 1 year warranty period Luminescent Display at 165 PM2519 01 Automatic Multimeter 70 Series Handheld Multimeters The new Philips PM2519 01 Digital New range of 3 DMMs from Fluke Fluke JF
384. t card number Or of course you can buy at our showroom between 9 00 6 00 Monday Friday 9 00 1 30pm Saturday Microvitec Cub 14 monitor Please send me AHigh Resolution Colour Monitor s at 4229 95 each ex Connection lead s at 6 00 each I understand carriage per monitor will cost an extra amp 7 00 A High Resolution Monitor including VAT lead and carriage costs 279 39 Lencloseacheque for amp Orplease debit my credit card account with the amount of amp My Access Barclaycard please tick no is MODEL REFERENCE RESOLUTION 1302 2 High Resolution 580 X 470 Pixels CRT 14 SUPPLY 220 240v 50 60Hz EHT Minimum 19 Sky Maximum 22 5kv VIDEO BAND WIDTH 10MHz DISPLAY 80 characters by 25 lines SLOT PITCH _INPUT VIDEO 0 41mm R G B Analogue TTL Input SYNC Separate Sync on R G B Positive or Negative EXTERNAL CONTROLS Onoff switch and brightness control Name Address Please state the make of your computer pus Telephone Opus Supplies Ltd CIRCLE 34 FOR FURTHER DETAILS WWW americanradiohistorv com s Fig 2 Amonitor is best for high density text display but a monochrome tv set with minor alterations can give satisfactory results This modification for Ferguson Ultra 3840 3845 3847 3848 6840 and 6845 tvs allows the set to be switched between com
385. t cater for com plete tracks In this extreme case a maximum size jump will take place whenever the travel limit is approached The head jump must take place during the vertical interval 1n order that it shall not occur in a visible part of the picture There is however a further difficulty In C format vertical interval sto rage is optional and vertical detection is done by locating the equalising pulses which are at the end of the main field track These pulses are relatively narrow and could be missed in the case of dropout They are thus predicted and validated by counting lines along the field track The 37 line timing shift between adjacent fields has been mentioned if a jump takes place this shift has to be taken into account in order to locate the equalising pulses cor uc en the tape speed is varied the head to tape speed changes causing the off tape sync pulses to change frequency the tape head contact is not con tinuous the machine has to maintain sync from track to track by counting extrapolated H sync pulses at the same frequency as they are coming off the tape A circuit is incorporated which measures the off tape line period in cycles of a reference clock and which can generate H pulses sep arated by that period during the vertical interval By counting these H pulses and modifying the count by 31 lines for every track jumped the machine can always know where it is in a field and
386. t maximum speed Direct current supply for this stage may come from the tv in valve sets the sound output valve cathode might be used The prototype gave rise and fall times of 200ns corresponding to bandwidth of 5MHz which should be sufficient for most home computers Bandwidth is mainly limited by the opto coupler and faster devices should work with only minor modifications since the driver bandwidth is about 20MHz Layout is critical all tv circuit WWW americanracdiohistorv com tracks should be separated from the grounded side by at least 4mm for insulation and signal paths should have minimum stray capacitance Video signal from 759 coaxial cable is terminated and should be about 1V pk at the input and large values of C are required for faithful reproduction of frame sync pulses Output is about 4V pk and may need to be divided for some sets J A McLay Ballincollig Co Cork Ireland 8 to 12V chassis 49 instruction i CIRCUIT IDEAS 0v 45V Repeat for 01 07 Agro A45 c pu and memory control lines Accentuated metronome Loud regular pips clearly audible even above my attempts to master the guitar are generated by this metronome Each pulse from IC triggers a fixed duration pulse from IC which drives the loudspeaker through Tr Normally common collectors of Tr are approximately at ground potential but counting and decoding circuits
387. t would not be neces sary to provide an additional one for the extra note However this would lead to reading only six bits per byte causing either wasted memory if the inputs are to be stored or a complex software re Further unless complicated wiring was used to connect keys to multi plexers which would not lend itself well to p c b layout the bit mapping involved would need extra software The small addi tional cost of two extra multiplex ers used offers two advantages By taking six keys to each mul tiplexer seven on the last one an octave of 12 notes fits into two multiplexers This makes it much easier to keep track of which bit represents which note Bit zero pin four of all the multiplexers is grounded Thus the first byte read should be FF hexadecimal since the outputs are inverting Keyboard software and control are outlined in a second article 29 QUALITY COMPONENTS FROM CRICKLEWOOD This list contains only fraction of our stock which is constantly being updated Prices quoted are for one offs quantity discounts by negotiation Official orders from Schools colleges Goods Dept etc welcomed WE SPECIALISE IN CREDIT CARD PHONE ORDERS A quick call will check stock position and current prices Prices subject to change Add 60p p amp p 15 to all orders Catalogue 40 A4 SAE envelope All in stock items despatched same day unless notified C EES S dies RIC ELE
388. tal of 20 broadcast channels Of the remaining five optical fibres constituting the 10 fibre link three will be for dedicated tv bandwidth channels such as on demand video library and video tex again multiplexed four per fibre Each fibre will be optically modulated by analogue intensity modulation The remaining two fibres will carry switching and control signals one upstream and one downstream At ahub site the optical signals are simply regenerated and rel ayed out to the wideband switch ing points A firm decision does not seem to have been taken whether to use an injection laser diode along with an avalanche photo detector at 0 85um graded index fibre for the primary links or whether to upgrade an 1 1 4 or 1 4 at 1 3mm with a fet receiver again using graded index fibre What is cer tain is that in the primary links the five fibres containing the 20 broadcast tv channels will be opti cally tapped to serve several switching points The primary links between hub sites and switching points will be less than 5km in length Within each wideband switch ing point a microprocessor con trolled matrix type of routing switch will route the 20 broadcast tv channels as demanded by each of up to 300 customers Each cus tomer will be able to receive two channels simultaneously Requests for individual video pro grammes in the form of discs will be relayed up through the system to the super head end
389. tc BNC Iittings for scopes counters generators etc 6 90 X1 X10 Switchable 10 00 0 8 26 Demodulator 16 00 X100 16 00 UK free with other Item or 65p par 1 to 3 kits 189 00 PRICES EXCLUDE VAT ORDER BY PHONE BY POST OR CALLIN SEE FOR YOURSELF 5 Send large SAE 20 UK Specification sheets 7 Any modei 59 Up to 1000 insta CIRCLE 4 FOR FURTHER DETAILS ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com Order by Post with CHEQUES ACCESS VISA or you can telephone your orders Available through Lombard Tricity Finance State which Send SAE Schools colleges companies Export free on written request nt credit 69 AMATEUR RADIO CALL BOOK 1984 edition Published annually this comprehensive directory of amateur radio stations in the UK amp Republic of Ireland incorp orates over 18 000 new callsigns and over 10 000 amendments Alt notified by the Department of Trade and Industry between August 1982 and February 1984 It also includes lists of RSGB affiliated societies groups and special callsigns For most entries the address published is the station location This gives the VHF UHF enthusiast an easy reference for beam directing purposes This new
390. ted to E of IC the transistor shown should have a base resistor and IC is the left hand section On IC Qand Q should betransposed We apologise for these errors 51 Remote volume control Heart of this circuit which requires only contact closures for volume increase decrease is a 4051 eight channel multiplexer operating in analogue mode The setting of this variable attenuator depends on output states of a 4029 up down counter which is stepped through on contact closures under control of a buffered clock signal from pin eight of the 4069 inverter Frequency of the clock is RC 2 2 and a 555 timer ensures that the volume level is low when the circuit is switched on One 4051 is required for each further audio channel the maximum number of channels only being limited by 4029 drive capability Dennis J Eichenberg Ohio USA Out In Amplitier 12V C 1 CK C PC PB B U D BIN BCD 4029 0 0 PD PALIN 2 150k 1 400 1N4148 Multi core cable Sk VV Dark Bright Mains filtered 100k 11000 5k 10V 100 ed E 1 52 WWW americanradiohistorv com Three channel light dimmer Using a non linear ramp to linearize power output this light dimmer with three channels requires few components and allows triacs to be fired remotely through non mains carrying
391. ten prefer single sideband operation where the technical demands are greater and the rewards higher With weak signals s s b has a consid erable advantage over f m and is essential for serious long dis tance working Nevertheless many old hands do use f m A chat on two metres possibly through the local repea ter can be a pleasant enough way of whiling away the traffic jams on the way to work type of set which has grown rapidly in popularity in recent times is the hand held portable transceiver Small enough to fit into the pocket it can be taken anywhere and for those with something grander at home it makes a convenient second rig The latest models offer perform ance figures and features scarcely For a more complex transceiver suitable home construction see Forresters design in Wireless World November 1982 to April 1983 with a postscript in August 1983 ELECTRONICS amp WIRELESS WORLD JULY 1984 inferior to those of larger units Most hand helds offer f m only though there is at present one s s b model The third main transceiver type is the basestation This is typically quite a large and com plex unit normally mains pow ered but often with a d c supply option for use with a car battery Most ready built basestation units are multi mode sets pro viding all three of the common amateur radio transmission modes narrow band f m s s b and for morse code c w Ampli tude
392. tep Down 240 10115 150W 9 250W 12 500w 14 2 _ GENERAL PURPOSE LOW VOLTAGE 12 x 8 1 30 16 6 1 30 14 x 9 1 75 12 x 12 1 80 16 x 10 2 10 Tapped outputs available Price Post ALUMINIUM BOXES 4x 4x 1A 1 20 4x 21x 2 1 20 3x 2x1 120 amps e o T2 dores and IV amp 6 8 e s 5 Pethe Eaa a 10x 7x3 3 60 12x 5x 3 3 60 2 amp 6 8 10 12 16 18 20 24 30 36 40 48 60 10 50 2 12 B Xx 3 4 30 9 x 4x 483 6 8 10 12 16 18 20 24 30 36 40 48 60 12 50 2 POTENTIOMETERS 5k 2meg LOG or LIN 1 5 50 DP 90 Stereo 1 5 5 8 10 16V amp 250 1 0 8 12V 5 5 00 1 1 10 DP 61 30 Edge Pot 5 S SP ap 6V 2 amp 2 00 1 150 15V 1 4 00 1 _ STER f150 60 m A 15 0 15V 2 amp 5 00 1 MINI MULTI TE Post 50p ma 50 1 20V 1 amp 4 00 1 3v 3 4 00 20 0 20 1 350 1 Pocket size moving coil instrument 4000 o p v 11 9 0 99 50 1 50 1 2 amb 4 00 1 ranges DC volts 5 25 250 500 AC d HRS 50 500 90 9 1 amp 3 50 20 40 60 3 50 2 hms 600 0 0 10V 2 amp 4 00 1 25 0 25 2 5 50 1 1000 DC amps 0 250uA 0 250mA Ohms 1030640 2amp 5 50 61 24v 5 amp twice 12 00 2 100ma 506 30 17 2 5 00 1 xean D MiroAme EZI BED 43 Ranges 1 000 AC DC 20 MEG 10 Post 1 12 0 12V
393. the carry signal At the other end ofthe system the 74LS85 four bit comparator produces a signal at pin 6 when and VDUSEL are low and Ay is high i e an address on the address bus is in the range 08000 to O9FFF and the v d u memory is switched into the memory Note that the four matching com parator inputs are switched so it is possible to relocate the area in memory at which the v d u appears switch on low The address is set up before MREQ by the 280 so the comparator signal can activate MEMDIS to inhibit a system memory cycle Further decoding is necessary though to ensure that this is a memory cycle MREQ is gated so that v d u signal SEL only goes low during a true v d u memory access Select signal SEL does several things It switches the four 7415157 multiplexers so that they direct bus address lines into the v d u memory and con nect the system WR signal to the memory and HD6845S The v d u memory and the 6845 are always selected so they would be incorrectly written to if WR wasn t gated It also enables the data bus buffer and clocks a set reset latch made from half of an 74LS00 When set this latch clears the 74LS273 forcing a dis play of one dot row of the charac ter generator corresponding to code 000 which happens to be blank The latch is reset by the character clock This latch sup presses the speckling effect men tioned earlier the algorithm being any c p u access during the
394. the development of high frequency power supplies to customer specifications We re offering excellent negotiable salary dependent upon qualifications and experience plus the usual big company benefits Assistance with relocation expenses may be available where appropriate interested Then please write enclosing a brief C V to Joan Thorpe Personnel Department GEC Telecommunications Ltd P O Box 53 SEC Coventry 1HJ Telecommunications Product Management Engineer Audio Mixing Consoles Sony Broadcast Limited one of the world leaders inthe professional sound broadcast and recording industry markets a complete range of professional audio equipment throughout Europe the Middle East and Africa In addition to microphones analogue tape machines mixing consoles and RF communication products we are also at the forefront of digital audio technology An excellent opportunity has now arisen to join ateam responsible for the product management of our professional audio equipment The successful applicant will provide support on our full range of mixing consoles There will be combination of in depth technical involvement with inter departmental and customer liaison This position will also entail some overseas travel as required Applicants should be educated to HNC Electronics or equivalent and have several years experience in the professional audio industry Knowledge of the operational feat
395. the rea sons behind the choice of par ameters used for the experimen tal systems together with a sum mary of the test results WWW americanradiohistorv com Fig 2 Frequency bands occup ied by the colour picture com ponents and sound signal of one television channel with the proposed digital sound signal added References l S R Ely 1983 Experimental Digital Stereo Sound with Terrestrial Televison field test from Wenvoe October 1983 BBC Research Department Report RD1983 19 2 D F Reid and N H C Gilchrist 1977 Experimental 704kbit s Multiplex Equip ment for two 15kHz Sound Channels BBC Research Department Report RD1977 38 3 M J Kallaway 1976 Experimental Four phase Differential phase shift keying System to carry two High quality Digital Sound Signals BBC Research Department Report RD1976 20 The vision carrier level is taken as the peak vision carrier power at the tips of the sync pulses and the levels of the main and second sound carriers refer to the respec tive levels of the unmodulated carriers 19 TWO STAGE 5 STRIPLINE PREAMPLIFIERS 9010 Tuned to your specified channels in bands IV or V TYPE 9051 9046 VMOS WIDEBAND LINEAR POWER AMPLIFIERS 4W 10W 20 watts RF output Without tun ing Power gain 10dB 24V supply TYPE 9046 100KHz 100MHz 4 watts k E 22 284 50 3 50 p amp p 9051 15MHz 20
396. the user port no specialist installation required No ROMS Supplied with extensive applications software Please phone for details 29 00 2 50 carriage ATTENTION All prices in this double page spread subject to change without notice PRINTERS ACCESSORIES MONITORS CASSETTE SOFTY EPSON 80 325 Paral Printer Lead 10 00d Microvitec 1431 14 RGB Std Res 179 00a RECORDERS This low cast intelligent eprom pro EPSON RX 80 FT 250 00a erial Printer Lead 8 00d Microvitec 143t PS 14 RGB PAL Sound 225 00a rammer can program 2716 2516 EPSON FX 100 480 00a EpsonSerial interface 2K8148 60 00c Microvitec 1451 14 RGBB MedRes 295 00a SANYODR 101 30 00b joa 2732 an adaptor 2564 EPSON DX 100 6375 00 EpsonSerial Interface 8143 650 00 Microvitec 1441 14 RGBHiRes 420 00a DatexSlimLine 20 00c ond 2764 Displays 512 byte page on Printer Sharer Cable Set 88 00c FX80Dust Cover 4 00d 203120 RGBStd Res 287 00a BBC Tape Recorder 2B 50b v dosis ri JUKI6100 Daisy wheel 350 00a Epson Paper Roll Holder 17 00c KAGAVision Ex 12 RGB 195 00a Cassette Lead 3 00d TV has a serial and paralle rou MCP40Col Printer Plotter 110 00a FX 80 Tractor Attachment 37 00c KAGAVision II HiRes 260 00a Computer Grade C 12 cassette 0 45d tines Can be used as an emulator cas Grafpad Graphics Tablet 1
397. this year and sell them mainly through Dixons Boots Comet and Rumbelows Amstrad Consumer Electronics plc Brentwood House 169 Kings Road Brentwood Essex CM14 4GF EWW 208 COMMUNICATIONS PROCESSORTO EASE NETWORKING Instead of employing separate communications devices protocol converters data concentrators multiplexers cluster controllers packet processors or nodal processors the Netway communications system from Scicon combines all ELECTRONICS amp WIRELESS WORLD JULY 1984 these functions into a single unit The system can be configured to connect virtually any type of microcomputer terminal wordprocessor and local area network with host computers from IBM ICL DEC and Burroughs Subsequent WWW americanracdiohistorv com additions of dissimilar equipment to the network can be accommodated by upgrades to the disc held software Netway has multiple distributed microprocessors within its hardware structure which has been optimised for communications It uses a dynamic multi tasking multi programming operating system called NCOS The central unit of the system Netway 200 with its 800Kbyte disc drive can be configured on line if necessary to support local or remote microcomputers and other devices using the protocols of the host mainframe Netway 200s works in conjunction with Netway 100s which interface individual devices into the network and with the Netway 150 which provides remote conn
398. tion Chroma band pass filter Luminance notch low pass filter Composite videc differentiatar or band pass filter High pass drive amplifier Limiter Fig 102 Picture enhancement tech niques and various methods of aperture correction can have adverse effects multiple images and movement blur viewers have said that the picture appears as if looked at through speckled glass Also if the noise spectrum lies in the 2 3MHz region noise on the final picture can be increased After viewing many live programmes it was concluded that it is better to get back more of the signal as originally generated at source REFERENCES 1 Drewery J O Filtering of Luminance and Chrominance Signals to Avoid Cross colour in PAL Colour System BBC Research Department Report 975 36 See also BBC Engineering 1976 2 Mullard Limited Mullard House Tor rington Place London WCIE 7HD Scan Velocity Modulation for the 30AX Tube TDA4560 40 3 Fischer T Digital v l s i breeds next tv receivers Electronics 1l 1981 eitmeier G A The Effects of analog on the picture quality of compo nent digital television systems SMPTE Journal Oct 1981 5 Auty Read amp Roe Colour picture improvement using simple analogue comb filters BBC Engineering Dec 1977 no 108 pp 28 33 Also SMPTE Journal Oct 1978 6 n C K P Digital standards conver sion Comparison of colour method
399. tive is a syn chronized event re triggered by reception of a previous locomo tive back at the terminus R the message delay through the sys tem is tightly bound At the far end of the highway the star coupler distributes the trains of information back to the receive terminals of all the stations Just as there can be more than one train on the line between Manchester and Lon don so will D Net support more than one train at a time given a detailed knowledge of the maxi mum propagation time bit slot lengths and number of stations This configuration seems extremely attractive at very high speeds beyond 100Mbit s because it retains a higher effi ciency than a passive bus arrangement Fibre optic sensors One of the aims of research work ers in the field of fibre optics has been to stabilize the transmission of information along an optical fibre against commonly encoun tered environmental changes for example pressure temperature strain etc they have succeeded to an extent where in many applications fibre optics is or will soon be the preferred trans mission medium In contrast at the opposite end of the applic ations spectrum there have been efforts to exploit variations in the same transmission parameters with respect to environmental disturbances in order to produce a range of fibre optic sensors transducers ref 5 Parameter Mechanism Coherence mode fibres Amplit
400. to the input of Continued on page 67 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com HIGH RESOLUTION THAT COMES HIGHLY RECOMMENDED 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 and remember as more and more resolution is available with new micros the need for a better display will be that much greater High recommendation indeed from Personal Computer News Meanwhile Acorn User said It seems that all normal and medium resolution monitors including the Sanyo are simply inadequate to deal with the Beeb s graphics and text output The JVC was excellent giving clear legible results Was the JVC better than the Microvitec Would I buy one Yes to both questions Our RGB high resolution colour monitor 580 X 470 pixels sells for 4229 95 excluding VAT that s a saving of over 100 compared with other leading monitors of similar specifications The unit has a 14 screen and is suitable for the BBC Micro Electron Sinclair QL Lynx Oric Apple and most other leading micros And naturally there s a year s full guarantee If you order your monitor by post you ll receive it within ten days by courier service Simply post the coupon below to Opus Supplies Ltd 158 Camberwell Road London 5 5 OEE Or telephone 01 701 8668 quoting your credi
401. tor for audio power amplifiers When positive output swing exceeds Vort Vat Vct Voe Vy the led lights Values shown are for a 34 0 34V supply and switch the led on at 64V pk pk but they may be altered to suit any single or dual rail power amplifier Tolerance on the switching point is about 0 5V due to junction effects Resistor R and the diode protect Tr during negative swing Conduit 4081 4401 gt D b 50 ELECTRONICS amp WIRELESS WORLD JULY 1984 4069 WWW americanradiohistorv com Artificial daylight For applications including tropical fish tank lighting this circuit gradually changes lamp brightness from off to full on in 25 minutes or vice versa depending on the switch position bridge rectifier and shunt zener diode provide mains synchronized d c pulses Triac firing through an opto coupler is from a unijunction transistor whose time constant is determined by a fet acting as a variable resistor The capacitor which biases the fet is charged or discharged depending on the switch position If R is disconnected brightness remains constant for at least 24h through charge in C J Clegg Doncaster Yorkshire Accurate switched gain for op amps Using a cheap array of seven equal resistors provides accurate switched op amp gains of one two five and ten times Resistance ratios for these gains in anon inverting amplifier are
402. transport control Each machine has both XLR balanced 6009 connections with a recording level headroom of 28dBm and phone unbalanced 10kQ connections Internal switching enables a 8dBm operating level Tascam see the use of the 40 series to be in smaller studios video post production dubbing and in training and education In contrast they have taken the opportunity to upgrade the two series 50 machines which they claim to be in the full professional league The 50 series now includes the 10dBv phono outputs and balanced 4dB balanced connections The two track 52 now has front mounted input and output level controls with pre and post fader switching The 50 series also offers remote control facilities for the transport and for selection of channels All switching and preset controls are available on the front panel Model 58 offers eight tracks on 0 5in tape Both the 52 and 58 machines have their bias and equalization set for use with high output low noise tapes such as Scotch 226 or Ampex 456 and may be easily adjusted to the correct parameters for such tapes If a particular low bias tape is to be used a small modification is needed to adjust the preset s range Distributor Harman Audio UK Ltd Professional Products Slough Bucks SL2 5DD EWW221 WWW americanradiohistorv com ju SERIAL COMMUNICATIONS Much more than a dumb buffer 15 the serial communications card which includes an on board M6800
403. tream low speed signalling so that customers may indicate to the star switching cen tre which service or channel they want at any given time The ELECTRONICS amp WIRELESS WORLD JULY 1984 Www americanradiohistorv com switching centre then routes the required signal down the cus tomers line which obviously only need sufficient bandwidth for one service at a time The pri mary routes from the main con trol centre to each of the switched star centres must of course be able to carry the full range of ser vices simultaneously British Telecom has gained valuable experience in this field with their Milton Keynes Fibrevi sion experiment in which 18 houses received a full range of services via optical fibres Based on this experience BT are pro posing a Multi star Wideband Network offering broadcast tv d b s tv subscription tv pay per view videotex alphanumeric and photographic individual video e g library discs home data services The proposed topology of the network is shown in Fig 4 The originating site or super head end would house the data library as well as the off air tv and video equipment This site would be connected by optical fibre super primary links up to approxi mately 20km in length with no repeaters to a number cf hub sites Each of these hub sites would simply regenerate and dis tribute the information over pri mary links to a maximum of 120 wideb
404. uality disc drives 250K 1 2 Mbyte high reso lution Monochrome 12 screen Expansion slots for printer modem upgrad able to 2Mbyte or Winchester 20Mbyte Computer based on CP M system Professionally made light alloy enclosure User manual and 10 diskettes 5 1 4 S W module Data Flow as starter pack included in price CP M is Digital research Trademark a selection from our huge stocks items reconditioned unless otherwise stated NEW SUMMER 84 CATALOGUE NOW OUT Covering our large stocks of Systems Peripherals Modules Terminals and Graphics equipment DEC SYSTEMS NEW PDP11 70 DEC DISK DRIVES TEN Ed 8102 DISK DRIVES FOR 11 23 SPECIAL PURCHASE FUME eo RIV22AK RLD 10MB Cartridge M20 Console 255 000 Disk Drive with 22 Bit Control Module _ with Cable and POP11 44 512KB cratch 2 x RMO2 Disk Drives Brand New 24 500 H9642 Cabinet 120 Console 35 000 PDP11 34A CPU 1019 Chassis 256KB MOS Cabinet 2 x RK07 Disk Drives 7 Multiplexor VT400 Console 10 250 DEC POP11 23AB CPU 514 Chassis 128KB MOS Memory MULTIPLEXORS DW11J 4 line Interface The universally popular 0 11 series ad NS Floppy Disk 0211A 8 line Master 1 800 Cabine 0218 8 line Expander 995 25738 Set 22750 POP11 23 128KB 2 x RLO2 Oisk Drives DIT Cabinet VT100 Console 7825 CIRCLE 51 FOR FURTHER DETAILS Port 03v cpu 5 Crasse 64KB 1 1 Int
405. ude refractive index change Wavelength refractive index Time Resolved Transient absorption or emission behaviour with feedback Polarization Changes inthe gyratory optical tensor 58 Interference between signal and reference fibre or different propagation modes in multi Modulation of transmitted light by absorption emission or Spectral dependent variations of absorption emission and Optical modulation and detection schemes as classified in an informative survey of fibre optic Detection Fringe counting or phase shift detection Analogue or digital Amplitude comparison at two fixed wavelengths or analogue signal for scanned wavelength Time delay pulse analysis Transit time of closed fibre loop Polarization analyser and amplitude comparison m Fibre gyroscope hydrophone multimode gauge for dynamic strain measurement Examples Straln pressure gauge using modulated micro bending loss Optical encoders Temp measurement by variable Fabry Perot cavity birefringent crystal semiconductor bandgap shift Temperature gauge by time decay ofrare earth ion fluorescence Nuclear radiation diagnostics using Cerenekov light Faraday rotation magnetic field transducer for non contact Current measurements Such sensors would exhibit many potential advantages usually for the same reasons as in commu nications namely electrical iso lation freedom from e
406. ur April leading article put the blame for restrictive aspects of our society on technocrats But government ministers rely on the advice from their ministers i e from civil servants and it has long been notorious that few graduates in science subjects make their way to the higher ranks of the civil service I guess that in addition to the fact that few of those who apply are View on end of rod showing ball races End plate Position of leds if required 1N4007 75 accepted it is probable that few apply So far from our troubles being due to technocrats many are due to the fact that few of those in a position to influence policy have what might be called an engineering outlook a knowledge of scientific fact and method plus some appreciation of the human side of management On the narrow issue of GCHQ Ican only say that those who go to work in such an establishment should be forewarned of the burden which security will place on them From the little which I have seen from the outside I would regard this burden of knowing things which must on no account be disclosed as the most serious factor associated with such work D A Bell North Humberside RELATIVITY Much discussion concerning the Special Theory of Relativity has appeared of late both in your letter columns and in other publications even to the extremes of scrapping the theory altogether and retur
407. ure dependent which meant detailed ELECTRONICS amp WIRELESS WORLD JULY 1984 studies of the power density spectrum with a variety of picture signals As expected from the vestigial sideband shaping the power density spectrum falling into the digital channel is triangu lar power density decreasing with increasing spacing from the interfering vision carrier This indicates that the frequency of the second sound carrier should be kept as close as possible to that of its parent vision carrier These conflicting require ments lead to a frequency spacing for the digital sound channel of 6 55MHz above the wanted vision carrier i e 0 55MHz above the main f m sound car rier Fig 2 Parameters of the modulation system adopted fo the experi mental equipment are given in Table 2 Conclusions The South Wales tests show that the experimental digital system is adequately resistant to impair ments to digital sound signal reception arising from low field strength multipath propagation ignition interference and distor tions in a long chain of transpos ers The results clearly show that when receiving low field strength signals directly from the main transmitter at Wenvoe the digi tal sound signal wil not on aver age fail before the picture became unacceptably noisy when receiving signals via a red broadcast relay station trans poser the average failure point occurring at a field strength well below the n
408. ures of mixing consoles and experience of console design would be particularly relevant We offer attractive salaries together with first class conditions of employment and relocation assistance will be given where appropriate If interested please contact Mike Jones Senicr Personnel Officer Sony Broadcast Ltd City Wall House Basing View Basingstoke Hants RG212LA Tel 0256 55011 u SONY Broadcast Sony Broadcast Ltd City Wall House Basing View Basingstoke Hampshire RG21 2LA 11 Telephone 0256 550 2619 THE PAPUA NEW GUINEA UNIVERSITY OF TECHNOLOGY ELECTRONIC SERVICE UNIT CHIEF TECHNICAL OFFICER COMPUTING Applications are invited for the above position which becomes vacant at the beginning of 1985 Duties include planned maintenance and repair of an extremely wide range of electronic equipment upkeeping of servicing records advisory service to academic staff supervision of technical staff and training of Technical Officer trainees The Electronic Service Unit is housed in recently enlarged air conditioned quarters and has a wide range of modern test equipment Computer facilities are available Applicants should be qualified to Technician Engineer level and should have substantial experience of electronic workshop technique and management Experience with microprocessor controlled equipment and microcomputers would be an advantage Salary Chief technical Officer Computing
409. w we need two technicians to back up our production team in our studios and on location You ll carry out routine maintenance and emergency repairsina 2 camera studio 3 machine editing suite and a fully equipped A V theatre photo studio and record library Location shooting and some setting up of presentation equipment on site will be required If you have an HNC or equivalent electronics some knowledge of video techniques and equipment and essentially a strong personal interest in electronics we will provide a competitive salary and comprehensive U NIPART 17 s 1 benefits Please write initially for an application formto SS PRESS lan Wells Personnel Manager Unipart International Unipart House Cowley Oxford 2PG 2629 Appointments Instrument Service Engineer fora key role in new ideas and technology 10 000 Beckenham Kent to join the Wellcome Foundation Limited a major group of chemical and pharmaceutical companies with headquarters in the UK and a turnover close to 700m As site based Instrument Service Engineer you would become a key member of the Instru ment Maintenance team for a group of engineers whose responsibility it is to provide anced electronic and precision mechanical engineering capability to the company This is a most unusual job and we believe you will have to be an unusual person to succeed in it You will need a very broad range of experi
410. was where they expected it to be They managed to turn on the 2MHz beacon to discover that the satellite was undergoing a weekly temperature cycle and that there were major problems with the 2MHz beacon system Now they have managed to bypass the problem by using the on board computer and have been able to send commands on the command uplink It is still necessary to stabilize the craft to prevent the temperature cycling and to get the main antenna pointing earthwards Then it will be possible to have a complete system check out and find out how many of Uosat 2 s functions are still working Even if everything else functions propertly it will not all be able to be used because of the use of the computer to bypass the 2MHz problems OED on computer The compilers of the new edition of the Oxford English Dictionary have decided to commit it toa computer This will enable the original 13 volumes to be expanded by the four supplement volumes and any new words can be easily inserted right up to the moment that the edition is prepared for printing There are over half a million entries which include over two million illustrative quotations giving a total of over 80 million characters In addition there is a variety of typefaces including Greek phonetic characters mathematical symbols and scientific formulae The system is to be based around an JBM 4341 central processor with both tape and disc storage printers and over 20 v
411. written as E 6 gt 001 where 15 the effective dielectric constant and g the effective con ductivity Du and Peake measured values of the relative dielectric constant 1 01 to 1 04 and effective conductivity g 0 2 to 0 4 X 10 mho m of the green leaves with varying percentage of water content 10 to 5096 and the volume concentration of the leaves in the range of 0 0003 to 0 001 at v h f They have also found that dielectric constant 15 nearly independent of frequency in the v h f band Spence and Heisler have reported dielectric constant of jungle environment as 1 02 and conductivity 10 mho m It is also known that Continued on page 29 ELECTRONICS amp WIRELESS WORLD JULY 1984 WWW americanracdiohistorv com VARIABLE SPEED VIDEO Variable speed video playback Using C format video recorders over a wide speed range Discussion continues with a description of the effect of the recording process on video waveforms At 2 and at 0 a single track jump is required every drum revolution whereas at 1X 3X a two track jump is required At intermediate speeds a sequence of single and two track jumps is made A single track jump will always be made but if the bimorph dis placement exceeds one track at the end of a field a two track jump is needed This process can e extrapolated up to any speed as necessary until the travel of the bimorph canno
412. y about the average phase A swing of 135 corresponds to 90 between the lines Spectrum interleaving demands a quarter cycle offset between subcarrier andline frequencies a direct result of PAL V switch Burst swing 15 another direct result of using V switch The combination of these two gives some interesting results The quarter cycle shift means that subcarrier phase advances by 90 from the start of one line to the next Burst swing is also 90 from line to line but alternately avanced and retarded On some lines then the 90 advance of the subcarrier cancels the 90 retarded burst giving nochange whereas on others the 90 subcarrier advance adds to the 90 advanced burst causing a 180 change resutt of this is a four line sequence containing relative to H pulses two identically phased bursts and two identicaily inverted bursts Figure 11 shows these effects burst phases normal andinverted are determined by the state of a squarewave of 1 4 line rate As 625 will not divide by four ittakes four frames before a given relationship between the burst phase control signal and the vertical pulse repeats The 25Hz offset is negligible within thefour line sequence described but it causes the four frame sequence to contain 2500 unique lines This extremely long sequence must never be broken if the signalis to be broadcast and this adds to the complexity of videotape editors and time
413. y required for a display increases less and less of the addressable memory remains for the program Paging is a technique where a block of memory can be tempor arily switched in place of another Use of paging means that v d u memory doesn t appear to take up any space in the main memory map with the proviso that soft ware that sends irformation to the v d u mustn t be in the mem ory segment switched out when the v d u is switched in and the penalty that v d u access is slowed down by extra switching software Other problems with memory mapped v d us are the extra circuits required to switch address lines to the v d u mem ory the arbitration needed and the screen disturbance which can occur when the c p u accesses the memory The problem of arbi tration is most relevant when dynamic memory with its need for orderly memory access is used As dynamic memory is cheaper and as higher resolution requires more and more memory this can lead to extra complexity or expense With static memory it is simply a matter of giving the c p u which will after all control the arbitration process priority in addressing and accessing v d u memory The disturbance occurs when the c p u gains con trol during active display period The v d u control cir cuits take bytes from memory in an orderly manner and pass them on for processing into video infor mation When a c p u cycle occurs this is interrupted the location a
414. y show the SE enety system to be more rugged than for either teletext 55 colour television pictures 31 Fib ti SC84 microcomputer 1019 0 3 22 With its own and communications Music keys forthe BBC controller SC84 s v d u by Brett Wilson microcomputer module allows 3000 text This last article looks at the bv R M Adelson characters 36 000 picture range of applications in Ec enim iM ien mer elements ora mixture of which fibre optic systems I the both are being introduced computer s own sound 37 generator or an external 61 m Improving colour Mi trolled 27 television decoding 3 by D C A Read E Variable speedvideo _ of David Read s series by A J Ewins by J R Watkinson includes Description of f s k John Watkinson continues surface wave filter and modulator and his description of the other component details demodulator for the effects of variable and discusses additional solenoid operated machine tape head speed on the picture enhancement for use with video waveform techniques microcomputers REGULARS 7 49 74 Communications Circuit Ideas Letters commentary RS422 to 232 converter Preferred values A use for tv isolated video driver GPIB combiner comments transmitters diplomatic remote volume control Is light velocity a constant radio telecommunications opto isolator circuits XY plotter act moonbounced tv Technocratic bondage 1 2 6 7 Relativity News
415. y to the work of Eli Cartan at the beginning of the century Cartan showed that a geometrical space could be discribed not only by vectors and tensors but also by more elemental entities variously called half vectors or spinors These entities were first used in physics by Pauli and slightly later by Dirac who in 1930 constucted a relativistically covariant wave equation in which electron spin is inherent What is now becoming apparent is that the spinor formulation may also be required to remove the difficulties of macro theory Dr Murray may denounce these developments as even more counter to common sense than Minkowsky space but then common sense has never been of much help in theoretical physics The nub of the matter is however easily explained to any reasonably competent mathematician Spinors are a sort of complex number distinguished from ordinary complex numbers by the fact that their law of multiplication is not in general commutative that is 15 not necessarily equal to BXA Ina group of spinors there is usually a sub group whose multiplication law is commutative and whose properties palely reflect those of the full group in the present case this sub group 1 the complex numbers What physics in general has been doing up to now is to use complex numbers when they should have been using the full group Thus they have been in much the same situation as electrical engineers trying to make do with real numbers

July - American Radio History

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