Home

Multiple- Source Lighting For Pro Photo Portraits

Contents

1. iji zur 2 ni EA m s 664664 6 I 4 MS WUN5ONHd 4 009 2 Icy Le gt RE s us ZOOPNT E o 4l 3 0000000000000000000000000000000000090 508 21914 ndo 8808 ul Pela lal ls a t sie iz m AOT 25 54 Tsay w 41 ST 21 ct 7 t Vs AU RSdeca dum 27 OU Fig 2 Complete schematic diagram minus dc power supply for Digital Signal Generator add on March 1991 MODERN ELECTRONICS 31 Say You Saw It In Modern Electronics a Ta m PARTS LIST Semiconductors U3 U4 U5 74HC373 U6 74HC04 U7 74HC139 U8 27C64 09 6264 U10 8284A U11 80C88 012 82 51 U13 81C55H D1 D2 D3 IN4002 diode 1 6 144 crystal Capacitors C19 thru C26 0 l F monolithic C18 C28 C29 C30 22 uF 16 vol
2. C ur 2 ss 2 2 o W 21 o a U g at 3 0 S 3 gt g Es v o lt 5 2 3 og O g o c o uc m gt 2 Ee eg 2 ME o o 3 om a oM oZ O Say You Saw It In Modern Electronics Electronics Workbench The electronics lab in a computer m SO oR 905 WN N Gh WO ean An example of the unique yan On screen test instruments NS e Bode plotter Function generator Multimeter Dual trace oscilloscope Electronics Workbench is pretty amazing Jerry Pournelle InfoWorld Electronics Workbench is simple and intuitive to use yet powerful Build circuits easily with the mouse driven graphical interface Simulate both analog and digital circuits Test circuits with on screen simulated instruments 3s 2 ciecurr 7 F GO 860 x d R tu t gt ES vov Tj pe SJ a 2 4 3 4 FT i 5 i E NE gt 550 t ix 1 x t 1 1 t 29 k JEDE 29 2 E i t o E ra E Analog Module Digital Module Special Offer Electronics Workbench for only 295 with this
3. sinner 203 287 1976 FAX ORDERS AND BIDS ACCEPTED Liectritied WE WILL TRY TO BEAT ANY PRICE ON ANYTHING FROM ANYWHERE A TRULY PROFESSIONAL STAFF WITH A COMMITMENT TO SERVICE COMPUTER COUNTRY AMAZING ONLY 5 1699 GOLDSTAR 120 Day On Site Service Additional On Site Service Available SHARP MZ 100 LAPTOP Fast 10 MH2 8088 CPU High Definition Backlit Supertwist Display 640 x 400 Resoution with 4 Shades of Gray 2 Internal 3 5 720K Drives 640K of Ram Expands to 1 6 MB Battery incl or AC Operation S0 Keys with Numberic and Cursor Kaypads Para lel Serial Clock MB DOS 3 3 8 GW Basic 322 Wight 10 8 lbs 1 Year Warranty from Sharp Sham Returbished Brand New Co AMAZING Options Availe ble Quantity Discounts 100 IBM Corrpatible 549 386SX 16MHz 512K Installed Baby AT Case 200 Watt ower Supply Mi BIOS ZERO WATT STATE 80387SX Socket Up to 4MB on the Motherboard 101 Deluxe Keyboard 386 20 MHz System Includes 40 MB System amp Goldstar Color Monitor 1MB High Speed DRAM expands eS to 10 MB Memory Upgrades Avail 40 MB Seagate Hard Drive 28 MS ALPHAWORKS SOFTWARE Larger Drives Available 1 2 MB Floppy Drive VGA Monitor Card Wordprocessor Spreadsheet Data Base Manager Spellchecker and Thesaurus Communication Software and Tutorials 8 Slots Reset
4. C Air Conditioning Heating amp Refrigeration diagnostic card to identify individual defec Name please print Age tive RAM chips locate interfacing problems and pinpoint defective support chips Plus Address Small Engine Repair 11 Security Electronics you learn to use your QuickTech diagnostic software to test the system RAM and such City State Zip Accredited Member National Home Study Council 4 031 E NEW PRODUCTS For more information on products described please circle the appropri ate number on the Free Information Card bound into this issue or write to the manufacturer Autoranging 100 MHz Analog Digital Scope Leader Instruments Model 3100D 100 MHz analog digital oscillo scope features separate 4K memories for display and reference 40 Ms s maximum sampling rate and 100 Ms s equivalent sampling It also of fers CRT read outs with cursors for voltage time frequency phase and ratios for voltage time and dB as well as additional comment lines Re sults can be downloaded to a com puter via a GPIB interface to an HP GL plotter for hard copy printout Up to four waveforms can be stored in memory Waveform expan sion of held information is possible from x1 to x100 with automatic interpolation Data stored in the dis play memories can be simultaneously displayed and overlaid onto data re called from the reference memories
5. 340 E FIRST ST DAYTON OHIO 45402 IDLER TIRE KIT This popular kit contains 170 of the 1 5 mostpopula lt gt 5 idler tires 10 each of 17 different 24112 save d money by having the right tire in stock Also included is a comprehen sive cross reference listing over 80 manu facturers assembly numbers and over 200 model numbers All tires are available individually for reorder 49 MD 400 900 VCR REPAIR PARTS KIT With this convenient kit you can BSE von Mam do most of your VCR repairjobs 21 same ao As parts for RCA Hitachi Sanyo Lloyds Panasonic Sony Sharp JVC and more Over 45 parts in all All parts are available individually for MD 400 950 89 VCR SPRING ASSMT A wide T of springs kK used brand V Springs etc 11 tension springs and 5 pressure springs MD 430 300 317 VCR WASHER 55 assortment Clutch springs idler springs tension Awide assortment of plastic washer used in clutch ass mblies and idlers 150 pieces split ring and regular MD 430 305 5 we CALL TOLL FREE FREE CATALOG 1 800 338 0531 CIRCLE NO 39 ON FREE INFORMATION CARD EDITORIAL I Printed Circuits As you know many of our construc tion projects are accompanied by printed circuit board foil patterns and component placement guide
6. J Fillmore 93015 49 Powerful Disassembler Snooper Help File Disassemble Searh Prnt a L k 5 emit A Processor 8085 87 no paiches iiid SABES Oey NN executable 2 3 One 1001 8 500720 ne Jump i lt ro sign program mo snorb00724 mp shorib 0 6t 2271 turns it mon 000 0 5m u 00 24 into fs ox 02s WOAD b 02 28 assembly ze x Bep 1 es bx 0 030 o5 12h un anguage mo WORD PIA 00711 source codd pon THA sino 2 so unique but Snooper is intelligent It automatically comments the source code and labels jump targets Snooper even includes a patcher to make small changes to a program without time consuming reassembly For more extensive changes Snooper is compatible with Microsoft and Borland assemblers Snooper gives you commented source code for almost any DOS file including COM EXE SYS Its pull down menus and on line help make disassembly fast and easy So what s this good for Well it s the best way around to learn assembly language and to make changes to software when you don t have the source code Cat SNPR 49 Order today Please rush the following products to me right away understand my purchase is covered by Central s 30 day satisfaction guarantee 11 I m not ready to o
7. REMOVE IC s FASTER _ THE 7 SECOND IC REMOVER 8 A4 with this simple invention than any other method including 6 000 vacuum de Soldering stations Speed up your repairs and salvage hundreds of good IC s per hour from junk boards Won t damage IC s or circuit board This is a money making labor saving tool Fits Radio Shack or Ungar soldering irons soldering iron not included Complete set of 8 desoldering bits Remove6 thru40 piniC s 89 95 Complete set of 10 desoldering bits Remove 6 thru64 pinlC s 1 1 4 95 LEARN THE SECRETS OF HOW TO FIX ELECTRONIC EQUIPMENT FASTER ON OUR REPAIR TECHNIQUES ON VIDEOTAPE Learn our techniques and make more money repairing electronic equipment These tapes are packed with much practical information that will Save enough of your valuable time to quickly pay for the tapes Learn from an expert what fails why it fails how to find it faster and how to fix it faster Much of this information is available nowhere else These tapes start at the beginning for beginners but cover each subject so thoroughly that even old pros will tearn valuable new techniques and skills SEND PAYMENT WITH ORDER AND WE WILL PAY SHIPPING ORDER 14 TAPES FOR 499 95 OR SEND 575 00 FOR ALL 16 TAPES How to use a Voltmeter 1 hr 51 min 39 95 How to use alogic probe and logic pulser 39 95 abo
8. 39 95 Job opportunities and money making opportunities In electronics 45 min 39 95 Troubleshooting and locating component failures 1 hr 10 39 95 Power Supplies Linear and Switching 42 min 39 95 VRS ELECTRONICS BOX 813 ME SELMER TENNESSEE 38375 TELEPHONE 601 287 1594 CIRCLE NO 29 ON FREE INFORMATION CARD March 1991 MODERN ELECTRONICS 77 AVCOM s New PSA 65A Portable Spectrum Analyzer The newest in the line of rugged spec trum analyzers from AVCOM offers amaz ing pertoimance for only 2 855 AVCOM S new PSA 65A is the first low cost general purpose portable spec trum analyzer that s loaded with features It s small accurate battery operated has a wide frequency coverage a must for every technician s bench Great for field use foo The PSA 65A covers frequencies thru 1000 MHz in one sweep with a sensitivity reater than 95 dBm at narrow spans he PSA 65A is ideally suited for 2 way radio cellular cable LAN surveillance MODERN ELECTRONICS MART Classified Commercial Rates 1 per word 15 word minimum 15 00 prepaid Word count includes name and address ZIP code and abbreviation each count as one word P O Box number and telephone number count as two words each Indicate free cate gory heading Computers Communications Electronics Video or Miscellaneous A special heading is available for a
9. FORTY NINE PROJECTS 3312 23 95 2613P 17 95 books are hardcover unless number 15 followed by a for paperback THE THYRISTOR BOOK WITH FORT Y NINE PROJECTS 3307 26 95 Counts as 2 1604P 17 95 3360 29 95 Counts as 2 3374P 16 95 2987P 16 95 3145 19 95 FREE when you join the Ecectaonics 15 Easy Electronic Projects 3 From Delton T Horn 5 ex Projects you can build some unique Z Value EN some old favorites from the author s INS vast treasury of electronics know how Delton T Horns All Time Favorite Electronic Projects Membership Benefits 9 Big Savings In addition to this introductory offer you keep saving substantially with members prices of up to 509 off the publishers prices Bonus Books Starting immediately you will be eligible for our Bonus Book Plan with savings of up to 80 off publishers prices Club News Bulletins 15 times per year you will receive the Book Club News describ ing all the current selections mains alternates extras plus bonus offers and special sales with scores of titles to choose from Automatic Order If you want the Main Selection do nothing and it will be sent to you automatically If you prefer another selection or no book at all simply indicate your choice on the reply form provided You will have at least 10 days to decide As a member you agree to purchase at least 3 books within
10. TW Ham Radio Bookstore Main St Greenville NH 03048 0498 ORDER FORM Please send me the following issues 3 50 each IU Fer Owics 800 457 7373 Number ordered 2 3 50 each NAME Total Payment Enclosed ADDRESS CITY Say You Saw It In Modern Electronics RACK CHASSIS FOR THE CONSTRUCTOR CONSTRUCTED OF ALL ALUMINUM PARTS THE FRONT amp REAR PANELS ARE CLEAR BRUSHED ANODIZED THE BALANCE OF THE PARTS ARE BLACK BRUSHED RU 1 75 SHIPPED FLAT UNASSEMBLED ANODIZED MODEL SIZE H W D PRICE SEND FoR mer CATALOG 1845 1 75 19x5 28 00 AL 3 RACK CHASSIS RACK PANELS 1RU7 125x19x7 30 00 SHEET METAL PUNCHES 18010 1 75 x 19 x 10 32 00 2 HAND PUNCH TOOL 2805 350x19x5 30 00 Perla R 2RU7 350x19x7 3200 ANO OUR UNE OF OVER 29010 3 50 x 19 x 10 34 00 SEMLPROFESSIONAL 3RU5 525x19x5 3800 MO PRODUCTS 3RU7 525x19x7 40 00 LM 3RU10 5 25 x 19x 10 42 00 FACTORY SESCOM INC UPS GROUND FREE 2100 WARD DR SHET DAY 00 HENDERSON NV 89015 U S A 702 565 3400 FAX 702 565 4828 CIRCLE NO 13 ON FREE INFORMATION CARD CABLE MATE INC Are You Tired of Paying Outrageous Fees All makes and models of cable equipment shipped within 24 hrs Quantity discounts For free catalog send S A S E to Cable Mate Inc 450 Shag Bark Algonquin 60102 C O D orders accepted CALL FOR PRICES TODAY 80
11. ergy available and is divided between flash heads Hence there s no need for steering diodes This supply could be implemented with a full wave rectifier circuit with a bit better charging efficiency Construction The minimal design power pack can be built into a much smaller enclo sure than was recommended above A double U shaped utility box measuring 8 6 x 3 inches is suit able Again you should collect all the components to be used before set tling on a given size enclosure No chassis as such is needed for building the power pack The top of the enclosure serves as the control panel on which you mount the POW ER Switch POWER indicator lamp READY indicator lamp fuse holder SYNC connector and a handle One of the 6 x 3 inch ends of the enclosure accommodates the three Sockets for connecting the flash heads to the power pack Secure the power transformer to the underside of the control panel and attach the single energy storage capacitor to the other end of the box with a ring clamp Use terminal strips to mount the few circuit components and wire together the components using the point to point scheme Compared to the more elaborate design this minimal design power pack is much simplified Neverthe less it s an easy and inexpensive way to get involved with multiple head lighting setups If you go this route and later wish to upgrade to the more elaborate design the compo nents can be directly sa
12. instructions to in the 8085 1D started and store these processor instructions In permanent memory in a 2816 E PROM Teaches you about input and output ports computer bmers Budd your own keyboard and leam how io scan keyboard and display previous computor knowledge required Simple easy understand instrucbon teaches you to wnte in machine langui ROBOTICS KIT FOR ABOVE 8010 71 95 Sine Square Triangle Ramp 210 2MHz Freq Counter 10MHz SV at 5A Fuly regulated Short circun protected with 2 limit control 3 separate supplies 660 with Analog Meters 175 GF 8015 without Freq Meter 179 WE WILL NOT BE UNDERSOLD amp SALES INC 15 Day Money Back Guarantee NLA 1245 Rosewood Deerfield 60015 2 Year Warranty sre sesion 810 IL Res 7 Tax 800 292 7711 708 541 0710 WRITE FOR FREE CATALOG CIRCLE NO 36 ON FREE INFORMATION CARD March 1991 MODERN ELECTRONICS 17 Project March 1991 Modern Electronics Telephone Call Restrictor Computerized device prevents outgoing calls to 1 900 and 976 toll numbers By Steve Sokolowski ome ten years ago the tele S phone company introduced a new type of service that fora predetermined price per minute let callers dial numbers to listen to 60 second comedy skits This dial it service is now thriving Now there are a horde of phone services prefaced by 1
13. 0 1 4F ceramic disc 3 7 15 25 volt electrolytic C4 C5 22 nF 25 volt electrolytic C6 C8 450 pF ceramic disc 10 11 2 200 25 volt electro lytic C12 C13 0 1 4F tantalum C14 C15 0 22 yF tantalum Resistors 4 watt 5 tolerance R1 220 000 ohms R2 R5 470 000 ohms R3 R4 15 000 ohms R6 4 700 ohms R7 R11 R20 10 000 ohms R8 R10 18 000 ohms R9 R12 R14 3 300 ohms R13 2 200 ohms R15 6 800 ohms R16 R17 5 600 ohms R18 R19 33 000 ohms R21 500 000 ohm panel mount linear taper potentiometer Miscellaneous F1 0 5 ampere slow blow fuse L1 L2 50 4H inductor S1 Spdt toggle or slide switch S2 Spst toggle or slide switch T1 24 volt 300 mA center tapped power transformer Perforated board with holes on 0 1 inch centers and suitable soldering hardware see text suitable enclo sure see text sockets for all DIP ICs fuse holder ac line cord with plug microphone panel mount con nectors lettering kit clear acrylic spray 4 inch spacers machine hard ware hookup wire solder etc Say You Saw It In Modern Electronics positive excursion Select a point and draw an imaginary line down to the carrier signal You ll notice that if the carrier signal is positive the chopped signal is also positive and vice versa In essence the carrier sig nal is multiplying the chopped signal by 1 and 1 create true multi plication the chopped sign
14. 941 t AWN Ou In hexadecimal Low Frequency Output Format Tone in Hz 3 2 1 0 1 209 1 336 1 477 1 209 1 336 1 477 1 209 1 336 1 477 1 336 1 209 1 477 1 633 1 633 1 633 1 633 Ormen or COO a C Que D or or OK Of Continued page 76 72 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics DISCHARGE PROTECTION 3329 29 95 Counts as 2 10018 539 95 2898 15 95 2809 29 95 SELECT 5 BOOKS for only 5495 S values to 127 70 IK and get a FREE Gift NX 5 X SAN 3260 22 95 Your most complete source for electronics books for over 25 years A ENCYCLOPEDIA OF ELECTRONIC CIRCUITS VOLUME ONE 1 1 1 3 1938 60 00 Counts as 3 FIBEROPTICS AND LASER 2981 16 95 BOUR ELECTRONICS PROJECTS 1367P 24 95 DEL IET ALDIO ER UMENT 3219 27 95 Counts as 2 3258 Counts as 2 27 95 Counts as 2 VOLUME TW Osal 3031P 17 95 2880P 14 95 BEGINNER S TV REPAIR 804 521 95 1897P 15 95 Counts as 2 SS Ul rer EECTRONN amp E ELECTRONIC 6 PROJECTS 3205 24 95 3275 22 95 THE 24 COMPARATOR 58 800K WITH
15. Circuit details for an ac oper ated supply that meets these require ments are shown in Fig 3 E The power transformer for this supply circuit should be a plug in wall type unit to provide isolation between the 117 volt ac line and low voltage cir cuits in the Call Restrictor In operation the low voltage ac output from the secondary side of 77 is rectified to pulsating dc by the bridge rectifier made up of D through D4 The pulsating dc is then filtered to pure dc by C8 after which it is reg ulated to 5 volts by C8 and further filtered by C9 for delivery to the re maining circuits in the Call Restrictor Construction As you can see from the multiple sec tion schematic diagram in Fig 3 this is a fairly complex project However bear in mind that a lot of the circuitry shown represents repetitious wiring OL 1808 4 To Point C 9 1 To Point D e 6 9 1 199 3 814 220K Ril 1 478 8870 14 To 101 Pin 36 To ICI Pin 37 hr To ICi Pin 38 To ICL Pin 39 101 Pin 1 To 14 Pin 7 T Point A lL To Point B DISCONNECT RELAY n 202222 Point Line Sense Relay Contacts Red t A B To Restricted To Telephone Telephones Line J2 J1 Green Point D Oc 00 Green To 11 Pin 2 22 24 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics Wall Transformer Fig 3 E PARTS LIST
16. O Visa 1111 111 1 1 1 Card Expiration Date Signatur uum VISA CHARGE BY PHONE 9 AM to 4 30 PM Eastern Time from Ohio 1 800 523 9109 from all other states 1 800 321 2155 to the instrument s keypad By de tecting and acting upon these tones the 8031 is capable of tapping into the line via an output signal sent to the relay circuitry The G8870 receiver chip in the Call Restrictor is a very complicated de vice Older DTMF receivers required large bulky audio filters The G8870 on the other hand incorporates all the needed filtering inside an 18 pin IC Unlike other receivers of this type the G8870 does not need addi tional circuitry that would allow it to be connected directly across the tele phone line On board the G8870 is an opera tional amplifier that can be wired as a differential amplifier Details for the internal circuitry pinouts and pin functions of this chip are shown in Fig 2 Note that the telephone line wires across pins 1 IN and 2 IN through a series of resistors and ca pacitors that are wired to form the differential amplifier arrangement Internal circuitry of the G8870 di vides the input dialing tones into their high and low groups processes them and converts them into the bi nary table shown in the box Note that the G8870 chip requires a 3 58 MHz crystal for operation while the 8031 requires a crystal that is three
17. PASS Publishing P O Box 570 Stony Brook NY 11780 COMPUTERS COMPUTER Breadboard Interface works with any computer Plans 2 R amp L Electron ics Box 878 Lebanon OR 97355 COMMUNICATIONS PAN COMM INT L CATALOG Over 350 Kits Plans Books about Licensed unlicensed AM FM broadcasting Ham CB SW DX amplifiers 1750M transmitters Surveillance devices Computers Software Science Proj ects MORE 1 00 refundable Box 130 ME3 Paradise CA 95967 CLASSIFIED ADVERTISING ORDER FORM Mail this form with payment to MODERN ELECTRONICS Classified Dept 76 N Broadway Hicksville NY 11801 Name Street Address City State Zip Check category you wish to be listed under or note a special heading 6 additional you want Audio Communications Computers Miscellaneous Wanted Electronics Video Special Heading PRINTEACH WORDSEPARATELY Notethat P O Box numbers and telephone numbers must be counted as two words each Circle additional words you wish boldfaced at 20 more each initial boldface word is free Minimum charge is for 15 words Free Boldface 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15 16 16 17 17 18 18 19 19 20 20 PLEASE ADD Extra Bold Words 20 cents Special Heading 6 TOTAL PAYMENT ENCLOSED Check or Money Order Payment may also be made by MasterCard or Visa For this please fill in info
18. Semiconductors D1 thru 04 134001 silicon rectifier diode IC1 8031 microcontroller IC2 74L S373 octal D type latch 1 3 6264 15 SRAM memory IC4 74LS138 3 to 8 line decoder IC5 Programmed 2764 EPROM see Note below 1 6 08870 DTMF decoder see Note below IC7 CD4066 hex inverter IC8 7805 fixed 5 volt regulator Q1 2N2222 or similar general purpose silicon transistor Capacitors C1 C2 30 pF ceramic disc 2 2 16 volt electrolytic 4 7 10 0 1 ceramic disc C5 C6 0 01 uF ceramic disc 8 9 330 16 volt electrolytic Resistors 4 watt 10 tolerance R1 thru R8 R15 10 000 ohms R9 R10 R13 100 000 ohms R11 R12 47 000 ohms R14 220 000 ohms Miscellaneous RY 1 S volt dc spst reed relay RY2 Teltone line sense relay see Note below T1 12 6 volt 150 mA plug in wall type transformer XTAL1 11 059200 MHz crystal XTAL2 3 58 MHz crystal Perforated board with holes on 0 1 inch centers and suitable Wire Wrap or soldering hardware see text sockets for all DIP ICs suitable en closure machine hardware hookup wire solder etc Note The following items are available from Suncoast Technologies P O Box 5835 Spring Hill FL 34606 G8870 10 Tel tone line sense relay 5 75 programmed 2764 EPROM 7 six conductor tele phone cord 1 25 11 059200 MHz crys tal 1 75 Add 2 50 3 50 in Canada S amp H per order Florida residents please
19. Special purchase of new rechargeable nickel cad batteries 1 2 volts 1800 mAH PRICE REDUCED ON 10 OR MORE CAT HDNCB C 10 pieces for 42 50 4 25 each 100 pieces for 375 00 3 75 each POWER SUPPLIES 5 3 AMP Electronics 5N3 1 New prepped power supply with wires and connectors Soldered to the inputs and outputs Open frame style 4 94 X 4 03 X 2 Input 115 Vac UL and CSA listed Regulated CAT PS 53 10 00 each 12 Vdc 5 AMP ACDC Electronics 12N5 or equiv Input 100 240 Vac wired for 115 Vac Output 12 Vdc 5 amps Open frame style 7T X 4 3 4 X3 high Regulated CAT PS 125 37 50 each 24 Vdc 2 4 AMP Power One Inc 24 2 4 Input 115 230 Vac wired for 115 Vac Output 24 Vdc 2 4 amps Open frame style 5 62 X 4 87 X 2 50 CSA listed CAT PS 2424 30 00 each TOLL FREE ORDER LINES 1 800 826 5432 CHARGE ORDERS fo Vien MaaterCard or Discover TERMS Minimum order 10 00 Shipping and handling for the 48 continental U S A 3 50 per order All others including AK HI PR or Canada must pay full shipping All orders delivered in CALIFORNIA must include state sales tax 6 96 6 1 2 96 7 Quantities Limited NO C O D Prices subject to change without notice Call Toll Free or clip this coupon FHEE 60 Page Catalog Containing over 4 000 ITEMS ALL ELECTRONICS CORP P O Box 567 Van Nuys CA 91408 CIRCLE NO 35 ON FREE INFORMATION CARD March 1991 MODERN ELEC
20. and brings you crystal clear pictures WARNING The Digital Video Stabilizer RXII is in tended for private home use only It is not intended to copy rental movies or copyrighted video tapes that may constitute copyright infringement Visa M C COD 3 FEATURES Easy to use and asnapto install The best and the most exciting Video Stabilizer in the market State of the art micro chip technology 91009 automatic no need tor any troublesome adjust ments Works on all types VCRs TVs and Monitors Light weight 8 ounces and Compact 1x3 5x5 Beautiful deluxe gift box Uses standard 9 Volt battery which will last 1 2 years Similar units sold else where for 99 or more UNCONDITIONAL 30 DAYS MONEY BACK GUARANTEE FAST UPS DELIVERY Air Shipping availabie ToOrder 1 800 445 9285 or 516 568 9850 49 95 ea S 4torp amp h M F 9 6 battery not included SCO Electronics Inc Dept CME3 581 W Merrick Rd Valley Stream NY 11580 Jerrold SB w Tri Bi SuperTri Bi TBM Jerrold 450 combo Scientific Atlanta SA 8536 Pioneer Oak KN12 dE Hamlin MLD 1200 Tocom Stargate Panasonic 2 14 US Cable TV 4100 N Powerline Rd Bldg F 4 Pompano Beach FL 33073 1 800 445 9285 For Our Record I the undersigned do bereby declare under penalty of per jury that all products purchased now and in tbe future will pale be used on C
21. cluding hard to find items Call toll free 1 800 776 3700 American Design Compo nents Dept 112 031 815 Fairview Avenue Fairview NJ 07022 SURVEILLANCE COUNTERSURVEIL LANCE equipment catalog transmitters de tection equipment phone caller identifica tion 10 00 EDE P O Box 337 Buffalo NY 14226 SURVEILLANCE Audio Video Infra red Laser Equipment Industrial or Private 500 Item Catalog 7 00 Security Systems 3017D Hudson New Orleans LA 70131 ssi Say You Saw It In Modern Electronics e Confused by today s electronics e Looking to learn and develop your building skills e Want to explore beyond Amateur communications CALL TOLL FREE 800 457 7373 OMMUNICATIONS lt UARTERLY 282 Just 27 95 for a one year charter subscription usa only Save 2 OO off the regular yearly rate COMMUNICATIONS QUARTERLY will push the technical envelope to the limit Articles will be selected from only the very best available State of the art electronics like direct digital synthesis digital signal processing and computer control will be fully investigated and explained so that you can take advantage of these new technologies COMMUNICATIONS QUARTERLY will also have articles that cover high speed data communications the latest in antennas using computer designed models plus much more COMMUNICATIONS QUARTERLY is the publication you ve been looking for Challenge yourself tech
22. connectors in their respective loca tions Place a control knob on the shaft of the GAIN control Crimp and solder the free end of the other ac line cord conductor to one lug of the POWER switch Then use hookup wire to bridge from the other lug of the switch to one lug of the fuse holder and another wire to bridge from the other lug of the fuse holder to the unused transformer pri mary solder post Place a fuse in the fuse holder Interconnect the circuit assemblies and components mounted on the front panel as needed using hookup wire Make sure each connection goes to the proper pins on the circuit board assemblies Checkout amp Use Make sure U through 4 are not plugged into their sockets Connect the common lead of a dc voltmeter or multimeter set to the dc volts func tion to any convenient point in the circuit that is supposed to be at ground potential Plug the line cord of the transmitter into an ac outlet and set the POWER switch to Touching the probe of the meter to pin 7 of the UZ and U2 sock ets and pin 6 of the U3 socket should yield a reading of 15 volts Similar ly touching the hot probe to pin 4 of the and U2 sockets and pins and pins 4 and 14 of the U3 should yield a reading of 15 volts When you recertain that your wir ing is correct power downthe Trans mitter and plug the ICs into their re spective sockets on the main board Temporarily discon
23. correct the problem Even if you do not have access to an oscilloscope you can test opera tion of the Call Restrictor You do this simply by plugging its transform er into an ac outlet lifting the hand set from any telephone instrument connected to the line through the project and key the numbers 9 7 and 6 As the last digit is dialed the Call Restrictor should interrupt the line and you should hear dead silence Then 2 seconds later you should hear a dialtone Repeat this test by dialing 1900 and then 0 The line should go dead after each is dialed and you should hear a dialtone 2 sec onds or so later So far you have learned that the Call Restrictor will block the calls you do not want to get through Now dial legitimate number This time there should be no disconnect and the call should go through as it normally would As an added security measure the Call Restrictor is designed to prevent any call from being dialed out in the event someone accidentally or pur posely unplugs the power transform er from the ac line The Call Restrictor will now silent ly stand guard over your telephone line preventing unauthorized calls from being made to those toll ser vices that have been inflating your monthly telephone bill If you have been plagued by high bills for use of these services the Call Restrictor should pay for itself in short order ME o Re Say You Saw It In Modern Electronics
24. tiple peripherals Configuration of the hardware is automatically performed via a software utility provided with the stan dard product An on board floppy con troller operates as a standard AT style controller or as a secondary controller for athird and fourth drive An external con nector provides easy access for tape drives CD ROMs optical disks and other SCSI devices The AL 4000 architecture has features aimed at maximizing performance in cache and non cache environments Both read and write transfers are cached Un like cache programs that reside in system main memory and generally work with DOS the AL 4000 cache is independent of the operating system Certain operat ing systems and applications discourage caching outside control of the operating system software The AL 4000 was spe cially designed to offer cache memory and operate as a non cache adapter This was accomplished by creating a control bus equipped with its own SRAM memo ry and dual EPROMs In addition to providing impressive performance across the EISA bus the AL 4000 has high performance on the SCSI bus as well The AL 4000 incorpo rates a new SCSI II protocol chip Al though most disk drives today have raw transfer rates below the SCSI I 5 MB s limit many of the drives entering the market include cache memory With 256K of cache and look ahead schemes drives will soon be able to transfer in syn chronous mode at above SCSI I rates T
25. 1 800 44 HEATH 1 800 444 3284 r L YES Please send me a FREE copy of the HomeWorks by Heathkit Catalog Send to Heath Company Dept 079 034 Benton Harbor Michigan 49022 Name Address ED 240 Bull Data Systems Inc CIRCLE NO 50 ON FREE INFORMATION CARD ELECTRONICS NOTEBOOK Foil SEMICONDUCTOR Fig 2 The most important types of strain gages ble to detect strains along more than one axis by using two or more gages that are aligned in different directions One way this is accomplished is to stack two or more gages on top of each other as shown in Fig 3 SINGLE Another way to detect the direction of strain is to form several gages each aligned in a different direction on the same substrate The result is known as a strain gage rosette The principal direc tion of strain can then be calculated by in STACKED Fig 3 Single axis left and stacked right strain gages 60 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics serting the resistance changes of each gage into an equation whose derivation is Biven in Experimental Stress Analysis and Motion Measurement by R C Dove and P H Adams Charles E Merrill Books 1964 The same equation is given in Experimental Methods for Engineers by J P Holman McGraw Hill 1984 Figure 4 shows one kind of strain gage rosette A more common kind incorpor ates a cir
26. 2 775 20MHz Elenco Oscilloscope FREE DMM Elenco 35MHz Dual Trace 375 with purchase of Good Io 50MH m MO 1251 ANY SCOPE High luminance 6 CRT Qual Trace a 1mV Sensitivity BKV Acceleration Voltage 105 Risa Time X Y Operation Z Axis TV Sync Delayed Tnggering Sweep 2 1 Probes e Includes 2 P 1 Probes All scopes include probes schematics operators manual and 3 year 2 yrs for E enco scopes world wide warranty on parts amp labor Many accessories available for all Hitachi scopes Call or write for complete specifications on these and many other fine oscilloscopes WE NOW True RMS 4 1 2 Component Tester 6 CRT X Y Operation SCOPE PROBES P 165MHz 1 10x 519 95 P 2 I00MHz Ix 10 523 95 Digital LCR Meter CARRY E Digit Muttimeter Muttimeter Amm 1C 1801 COMPLETE LINE M 7000 CM 365 125 er 135 65 Measures FLUKE 05 DC Accuracy AC DC Voltage amp Amps cei 1uH 200H Resi Resistance to 2000M 1 5 basic aps 1p 200ut MULTIMETERS iis viis Diede Logic amp Trans tast Zero control Res 01 204 Models and daluxe case Capacitance to 200uF with case 1 83 23F 85 Functlon Generator Triple Power Supply XP 620 5F 87 Blox Aseombled m 56 9000 27F 8050 7 1545 73 8060 19001 210 15V at 1A 129 75 8062 28 95
27. 53 Electronics and You 201 PART 2 AC 71 min Electronics and You VT 202 PART 3 SEMICONDUCTORS Electronics and You VT 205 PART 4 POWER SUPPLY LEARN ELECTRONICS FROM VHS VIDEO TAPES CALL TOLL FREE AT 1 800 678 6113 mail check or money order to UCANDO VIDEOS BOX 928 GREENVILLE OH 45331 Our Video Tapes Are Designed To Make Learning Electronics Fun and Easy Electronics and You VT 207 PART 6 OSCILLATORS Electronics and You VT 208 VCR MAINTENANCE amp REPAIR VT 203 54 _ 32 95 INTRODUCTION TO VCR REPAIR VT 204 110 l 1 CIRCLE NO 32 ON FREE INFORMATION CARD 16 MODERN ELECTRONICS March 1991 obtained with the MFJ 208 vhf SWR analyzer from MFJ Enterprises without having to use a transmitter SWR meter or other equipment It permits accurate trimming of an antenna at a specific frequency im mediate observation of the results when an antenna is shortened or lengthened perfect adjustment of a mobile whip antenna finding the ideal place on a car for a mobile antenna seeing how SWR changes as a vehicle is driven under an overpass checking the SWR of the input to an amplifier and more In use the antenna to be tested is simply plugged into the coaxial con nector on the SWR analyzer the analyzer is set to the frequency of in terest and the SWR is read For m
28. 6 surcharge First word only is set boldface caps at no charge Add 20 for additional boldface words Non Commercial Rates FREE to subscribers as space permits maximum 15 words A recent MODERN ELECTRONICS mailing label must accompany ad advertisers with Box addresses must supply permanent address and telephone number Copy is subject to publisher approval Mailing Information Copy must be received by the publisher by the 25th of the third month preceding the cover date Send Advertising material with check or money order or credit card information Visa or MasterCard only with number and expiration date to MODERN ELECTRONICS Classified Department 76 N Broadway Hicksville NY educational production and R amp D work Options include frequency extenders to enable the PSA 65A to be used at SAT COM and higher frequencies audio demod for monitoring log periodic anten nas 10 KHz filter for 2 MHz DIV range carrying case AVSAC and more For more information write FAX or wr i F BRINGING HIGH TECHNOLOGY DOWN TO EARTH 500 SOUTHLAKE BOULEVARD RICHMOND VIRGINIA 23236 804 794 2500 FAX 804 794 8284 TLX 701 545 CIRCLE NO 31 ON FREE INFORMATION CARD Call 800 992 9943 Over 35 000 Electronic Components Call Today for Your CIRCLE NO 46 ON FREE INFORMATION CARD 78 MODERN ELECTRONICS March 1991 11801 VIDEO T V NOTCH FILTERS PHONE RECORD ING EQUIPMENT BROCHURE 1
29. Allow each coat to dry before spraying on the next Line the ac cord entry hole with a rubber grommet Then mount the fuse holder and circuit board assem blies in place using suitable machine hardware and 44 inch spacers for the boards Referring to Fig 7 and Fig 8 wire together the circuit boards Route the ac power cord into the enclosure through its grommet lined entry hole and tie a knot in it about 10 inches from the end inside the enclo Fig 10 Layout details for circuit board assemblies inside enclosure Large board at top is main transmitter circuitry Power supply circuitry is on two smaller boards shown at bottom Fig 11 Typical DSB C AM modulated signal as display ed on the CRT screen of an oscilloscope VOLTS gt BOO na oS Sz Say You Saw It In Modern Electronics March 1991 MODERN ELECTRONICS 45 Tw pO A E E e Sd sure Tightly twist together the fine wires in one conductor and sparingly tin with solder Determine how long the other conductor must be to reach one of the solder posts connected to the power transformer primary leav ing some slack Cut this conductor to length strip inch of insulation from it tightly twist together the fine wires and sparingly tin with solder Connect this conductor to either transformer primary solder post Mount the GAIN control POWER and MIC SIGNAL switches and AN TENNA MICROPHONE and SIGNAL IN
30. At Your Own Pace amp In Your Own Home Discover Your Career Potential In The Fast Growing Field Of High Tech Electronics you re anxious to get ahead and build a real career you owe it to yourself to find out about the Cleveland Institute of Electronics CIE can help you discover your career potential in the fast growing field of high tech electronics A career that will challenge and excite you every day reward you with a powerful feeling of personal accomplishment and deliver a level of financial security you may have only dreamed of before As the leading school in home study electronics CIE has helped over 150 000 students in the U S A and over 70 foreign countries get started in this exciting field To find out how CIE could be helping you read on then send for a CIE catalog TODAY A Growing Need For Trained Professionals The career opportunities shown here are only a few of the challenging high paying careers you could enjoy as an electronics technician You could be the brains behind the scenes of an exciting TV broadcast trouble shoot life saving medical equip ment design exotic new aeronautics systems CIE s job oriented programs offer you the quickest possible path to the career of your dreams And CIE also features military and union re training to build on what you already know Dozens 01 Fascinating Careers To Choose From Even if you aren t sure which career is best for
31. Hewlett Packard IBM Mannesmann Tally NEC Okidata Panasonic Printronics Seikosha Televideo Texas Instruments Toshiba 3199 179 149 DAC EASY LIGHTNING A Disk Caching ist 69 95 Call for Pricing Substantial Quantity Electrified Discounters x HOURS Mon Thurs 9AM 7PM ORDERS 800 678 8585 Fri Sat 10 6PM ONLY Customer Service amp Technical Support 203 287 1976 1066 Sherman Avenue CIRCLE NO 27 ON FREE INFORMATION CARD Dealer Inquines Invited Aa Proes sted are Cash Discounted Add 2 172 for MasterCard or AMEX Not fespormble for typographical eras Prices subject iD without notos Conn reudan add 6 sales Lax NY Sales Add NY Tar Quantities ere do not ndude kegm 3 weeks ior Personevcompany check dearance 20 festocking fes minmum on reume Compattalty not guaranteed Some system options may be relrbwhed IBM of intarnatonal Business 30 DAY MONEY BACK GUARANTEE Fuit Refund of HARDWARE Price on all Advertised Products Catalog Sent with All Orders Hamden CT 06514 FAX 203 248 8680 FAX ORDERS AND BIDS ACCEPTED V MODERN ELECTRONICS THE MAGAZINE FOR ELECTRONICS 8 COMPUTER ENTHUSIASTS MARCH 1991 18 26 38 47 59 66 68 VOLUME 8 NUMBER 3 FEATURES Telephone Call Restrictor Computerized device prevents outgoing calls to 1 900 and 976
32. Manhattan includ ing the twin towers of the World Trade Center and the Statue of Liberty the air conditioning tends to be somewhat less than effective Winter or summer it s about 90 by the time I leave in the even ing And if my PC and laser printer have been for more than a very few hours 1 go home medium rare Needless to say if I don t have to use the PC it stays off Over the years I ve also tried other methods to get me on the straight and narrow I ve had a variety of electronic organizers including the Atari Portfolio I reviewed a while back a Casio Boss and a Sharp Wizard Most of these are gather ing dust on a shelf or have been returned to the vendor They re all effective but they re also very time consuming to set up and use Personal Information Manager PIM software is another good organiz ing system but like the electronic orga nizers it s time consuming to set up and use and must be used conscientiously to be effective Most of the time I ve relied on the popular DayTimer notebooks though this last year I ve been using a clone of the almost ubiquitous Filo Fax It may not be state of the art in tech nology but for the 12 or so it cost it does let me keep track of appointments and other commitments For the past several months however I ve been using acouple of packages from Power Up that let me have the best of both worlds Calendar Creator Plus and Top Priority
33. Modern Electronics tached I then attached wires to the un painted end of the piano wire and to the conductive paint The completed strain gage is illustrated in Fig 7 When the wire was flexed the electrical resistance between the particles of copper in the paint changed It was therefore possible to monitor the movements of the rocket simply by connecting an ohmme ter to the piano wire conductive paint strain gage Conductive paints and inks can be used to make many kinds of strain gages The paint can be applied as a thin zig zag curved or straight line It might even be possible to make a template so that strain gages with similar dimensions can be made Whether or not two such strain gages with the same appearance also have the same resistance is another matter though Variations in the thickness of the conductive paint can make significant differences in the resulting resistance In any case of course the paint must be applied over an insulating surface And there must be a means for attaching leads to opposite ends of the painted re gion Often leads can be bonded directly to conductive paint It s also possible to solder leads to some conductive paints A better approach is to apply the paint to a very thin flexible etched circuit substrate on which a pair of electrodes have been formed You can then solder leads to the copper foil electrode Flexible copper clad substrate is available from some electronics
34. Postage amp Handling 4 00 Add a 23 channel Digital Signal Generator an 8088 based Computer Experimentet Platform to the Function Generator Board This project operates as a stand alone Digital Signal Generator capable of generating 23 different digital signals simultaneously Custom signal generator programs as well as 8088 based computer experiments Language Programming in upcoming articles down loaded from any IBM compatible Learn about Computers Digital Circuits and Assembly Postage amp Handling 4 00 OPTIONS Power Supply Kit 634 95 54 00 Matching Black Steel Cabinet 37 50 4 50 PH COMPLETE YOUR LAB With A Prototyping Station Features both solderiess and wire wrapping ing RE ignal With cables connecting 80 signals from the Digital Computer Experimenters Platform to the Prototyping Station 69 95 Postage Handling 54 00 OPTIONS Power SUB 34 95 54 00 Matching Steel inet 37 50 4 50 PH MasterCard Visa Accepted 203 355 2659 NETRONICS RESEARCH ANO OEVELOPMENT uMTED 333 Litchfield Road New Milford CT CIRCLE NO 48 ON FREE INFORMATION CARD CIRCLE NO 49 ON FREE INFORMATION CARD LICENSED ELECTRONIC TECHNICIAN aA Earn up to ager 30 an hour i and more NAE y 2 3M Learn at home in s i pare time ae 8 m No prev
35. RS Page 49 AMC 61 AS Electronics S hp 15 ii 78 B amp B Electronics 82 C amp S Sales n Cable Connection M Cable Mate Inc Cable Plus ES 82 Cable Ready Company 67 Central Computer Products M Cleveland Inst of Elec 19 Cov Command Productions ot Communications Quarterly 79 Consolidated Electronics 57 Cook s Institute 16 Deco Industries 25 f 57 5 9 Educalc 64 Electrified Discounters Cov 3 Electronics Book Club i al Global Cable Network P Grantham Heath Co T Information Unlimited Interactive Image Tech Jensen Tools KD Video Kelvin Electronics Listen Electronics MCM Electronics Electronics Mouser Electronics NRI Schools Netronics R amp D Ltd Pacific Cable Co Inc Parts Express International SCO Electronics Sescom Smith Design Technical Challenge Inc Trans World Cable Co U S Cable U S Cyberlabs Ucando VRS Electronics Video Tech Viejo Publications Visitect Inc We d like to see your company listed here too Contact Jonathan Kummer at 516 681 2922 Electronic Adver tising or Ken Wood at 407 264 0545 Computer Advertising to work out an advertising program tai lored to suit your needs CIE Gives You The Training You Need to Succeed
36. The Truth About Ef fective Bits from John Fluke Mfg Co Inc demystifies effective bit resolution EBR in digital storage oscilloscopes EBR has been the cause of much confu sion in the test and measurement commu nity This new Guide chronicles the mi gration of the DSO from its parent the oscilloscope and reviews sampling bandwidth and rise time accuracy versus resolution bits and effective bits and fac tors that affect accuracy and resolution In addition it provides insight on how EBR is measured how bandwidth relates to EBR how S N and EBR are related to each other and details of error sources CIRCLE NO 33 ON FREE INFORMATION CARD LEARN TO CLEAN MAINTAIN REPAIR FAX MACHINES HUGE NEW UNTAPPED MARKET prom Over 8 million Fax machines in homes offices predictions are for over 25 million by 1992 B Work fram yaur home van B Home study program gets you started servicing fax machines in 2 weeks B No special toals equipment needed Earn additional profits selling fax Supplies Fax machines are not cheap therefore you can get good for the repair Average Fax machine requires professional service every 18 months Home study training program includes full instruc tions on EVERY ASPECT of Fax maintenance repair FULL COVERAGE of how to set up your home based service business FREE DETAILS CALL 1 800 537 0589 Or Write To Viejo Publications Inc 5329 Fou
37. The six bit port is used as an in put port to read the program selec tor If the download mode is select ed the six bit port is available to pro duce digital signals or to act as an port The program toggles the ports to produce the digital signal trains The programs simply initialize the 8155 to configure the ports and timer operation Outputs are then set tothe value desired at the beginning of the digital signal train The system loops until the next change is required at which time the ports are changed This process is duplicated changing the loop time and the output data to produce the desired signal train The counter timer can also be used to produce digital signals In square wave mode the timer can be turned on and off to produce a predeter mined set of pulses The program then jumps to the beginning or waits for a system reset to begin again e Program ROM The program ROM is mapped at FE000 Unlike other processors the 8088 series 3 U looks for the first instruction at loca tion FFFFO which is 16 bytes from the top of the 1M address space The program starts with a jump to the base address of ROM After running When clocked the 74LS165 eight bit serial shift register shifts data toward the serial output pin X Parallel data is entered directly into registers that are enabled by a low level at the SH LD s
38. You ll be entitled to unlimited access to CIE s faculty and staff to assist you in your studies via a toll free 800 number six days a week 24 hour turnaround on grading your submitted exams CIE Bookstore privileges a patented learning method reference library a student faculty and alumni electronic bulletin board and a free issue of CIE s school newspaper The Electron All this knowledge and support will put you on the road to understanding digital electronics microprocessing principles computer systems telecom munications and much much more All This and Much More For ONLY Free Issue of The Electron Build your personal burglar alarm Instructors available 6 days a week 20 lesson books containing 39 theory and hands on training lessons and exams 90 Bookstore Privileges Patented Learning Method Electronic Bulletin Board 24 Hour Grading mum mam KA Yes send me CIE s 39 Introductory Electronic and Electricity Lessons and Equipment __ Address ____ City _ State Age Phone _ n EE BOOKSTORE 1776 East 7th Street Cleveland Ohio 41114 216 781 9400 BKO1 Total Merchandise Ohio Residents add 7 Sales Tax California Residents add 6 1 2 Sales Tax 1 Total this order Method of Payment Amount Enclosed Personal Check or Money Order CJ Master
39. add 6 state sales tax PARTS SUPPLIERS B G Micro P O Box 28209 Dallas TX 75228 214 271 5546 Digi Key Corp 701 Brooks Ave S Thief River Falls MN 56701 0677 1 800 344 4539 JDR Microdevices 2233 Branham Lane San Jose CA 95124 1 800 538 5001 If you have any experience at all in building circuits you should fairly easily build the Call Restrictor You can mount the components on perforated board that has holes on O l inch centers preferably with copper rings around each hole and point to point wire them together with Wire Wrap or soldered connec tions Your first step is to photocopy the schematic diagram sections so that you can strike off each wire run as you make it according to the Mas ter Wiring List Begin construction by mounting the sockets for the various DIP ICs on the circuit board If copper rings surround the holes on your board solder only the four end pins into place Use solder sparingly to avoid getting it on all but about inch of the pin lengths If your board does not have copper rings around each hole and the socket pins do not pro vide a friction fit bend the four end pins slightly outward to hold each socket mechanically in place Do plug the ICs into the sockets until af ter preliminary voltage checks have been made and you are satisfied that your wiring is correct After mounting the IC sockets mount the various components on the board If you are using the
40. are necessary for large systems are not used here The 8088 CPU is a relatively straight forward hardware device Address Data bus lines A0 through A7 are multiplexed so that they share this function with the eight bit data bus without creating conflicts or colli sions Address pins 16 through PAI9 are also multiplexed with various status signals In both cases the address informa tion is presented on the output pins of the 8088 during the first part of each machine cycle and is latched in to U4 through U6 when the CPU is sues an ALE Address Latch Enable signal During the remainder of the machine cycle time the low order address pins become the eight bit bi directional data bus and address lines PA16 through PA19 become CPU status pins All 19 address bits are latched and are connected to the 8088 Platform bus The bus includes all address da ta and CPU contro signals that are used as part of the 8088 Computer Experimenter Platform Clock Generator The 8088 re quires the use of 8284A clock genera tor U10 This circuit supplies the 8088 with a special clock signal that has a 33 duty cycle and is half the crystal frequency When power is turned on or the system is reset the 8284 generates a master reset Signal that is used to reset all peripherals and the CPU A symmetrical system clock labeled PCLK is generated for the 8088 system bus The 8284 also has provisions via the RDY and AEN signals that su
41. axis when in its MODULATOR ANTENNA BUFFER Eis Book of used n the AM Transmiter 6 Block diagram of the circuitry used in the AM Transmitter project March 1991 MODERN ELECTRONICS 41 vo inv 6 2 eo TO T OTH 2 2 3 Bru o o gt 39057 Hnos 96v IWI NI vNOIS Ort ent 2 ba ak za 1O c que 0400 4202 Q 5102r HZ 1937135 L 39067 92 9 9 13 91H ABA Lv 15 anro T Say You Saw In Modern Electronics 42 MODERN ELECTRONICS March 1991 EEUU Fig 7 Schematic diagram of basic AM Transmitter circuitry PARTS LIST Semiconductors BR1 200 volt 1 ampere bridge rectifier module D1 thru D4 1N4148 or similar small signal diode Q1 Q3 2N3904 silicon npn transistor Q2 Q4 2N3906 silicon pnp transistor U1 U2 LF356 operational amplifier U3 LM1496 balanced modulator U4 LM3046 transistor array U5 LM17816 15 volt fixed regulator U6 LM7915 15 volt fixed regulator Capacitors C1 C2 C9
42. current to reach the pre set limit the supply automatically switches to constant current mode The Model 1611 can be powered from 100 to 240 volt ac sources comes with hookup leads spare fuse parts list user manual and schematic diagram The supply measures 12 D x 64 H x 4 4 W 295 CIRCLE NO 14 ON FREE INFORMATION CARD Courteous Service Discount Prices Fast Shipping PEREEES IRONIES 567 Van Nuys 91408 New FLASH UNIT This NEW compact flash unit comes from a U S manufacturer of cameras Unit operates on 3 Vdc and measures 2 1 2 X 1 1 4 Ideal for use as a strobe warning light or attention get ter Complete with instruction on how to wire CAT FSH 1 3 75 each 10for 35 00 I New Reduced Price TOFLASH CAPACITOR Rubicon CE photollash capacitor 0 79 dia X 1 1 high These are new capacitors that have been prepped with 1 4 black and red wire leads soldered to the terminals 210 Mfd 330 Volt CAT PPC 210 1 25 each 10 for 11 00 100 for 100 00 Large quantities available Call for pricing FLASHING L E D Diffused L E D with built in flashing unit PULSE RATE 3 Hz 5 Volt 20 ma Unit continually flashes when 5 Volts is applied Operates between 4 5 Volts and 5 5 Volts T 1 3 4 size IDEAL AS AN INDICATOR BED CAT LED4 ae GREEN CAT LED4G 0 YELLOW CAT LED4Y nd 1 00 each 10 tor 9 50 100 for 90 00 HEAVY DUTY NICKEL CADMIUM C BATTERY Yuasa 1800C
43. for DSB and SSB are fairly complex Double Sideband With Carrier DSB C is the technical designation for standard AM which is what com mercial AM broadcasters use to de liver music news weather sports etc to their audiences The frequen cy spectrum of DSB C looks much like that of DSB except that it con tains a spike at carrier frequency fe with both bands along for the ride as in Fig 1 D The tradeoff between these AM modulation techniques is a matter of efficiency versus ease of implementa tion and cost of demodulation Be cause consumers want low cost re ceivers thesacrifice made is lower ef ficiency Greater efficiency is real ized in SSB and DSB systems but cost is much greater for receivers be Carrier Yref Digital to Analog Converter Digital Control Logic cause a synchronous modulator is needed for reception and demodula tion of DSB and SSB signals To be able to hear the information contained in an incoming signal the receiver must use circuitry that multi plies the incoming signal by a sine wave signal of exactly the same fre quency as the carrier Multiplying the incoming signal again shifts the spec trum But now the negative going spectrum falls into the place it started from but is at twice the original carri er frequency making it easy to filter out Thespectrum shifted to the orig inal position allows you to hear the information The circuitry required to achieve this
44. line The only conductors you need for this project are those that have red and green insulation on them If there are other conductors clip them away close to the beginning of the remaining outer plastic jacket Strip inch of insulation from the ends of the red and black insulated conductors Route these conductors through their respective entry holes in the en closure and solder the free ends of the conductors to the appropriate solder posts Make certain your connec Say You Saw It In Modern Electronics tions are properly polarized This done use plastic cable ties to secure the cables to the enclosure with suit able machine hardware Leave a bit of slack in the cables inside the enclo sure The ties will prevent the cables from being torn loose Checkout amp Use Before putting the Call Restrictor in to service it is a good idea to perform preliminary voltage checks to ascer tain that you wired it correctly For this test you need a dc voltmeter ora multimeter set to dc volts Clip the common lead of the meter toa point on thecircuit board assem bly that is normally supposed to be at ground potential Convenient points for this connection are the negative leads of C8 and C9 in the power supply section Make sure that the only IC on the circuit board assem bly is three pin regulator C8 Plug the wall mount transformer into its ac outlet Then touch the probe of your meter to pin 40
45. line for about 2 sec onds and then reconnect it again to wait for the next dialing sequence The sequence of required events are permanently stored in an EPROM Upon power up the EPROM pro gram is read into a 6264 memory chip Once this program is read the 8031 executes each step in the re quired sequence Once the restricted numbers are sensed the program tells the 8031 to deenergize a relay whose contacts are in series with the telephone line 1 1 0 PORT 1 1 PORT 1 2 PORT 1 3 PORT 1 4 PORT 1 5 PORT 1 6 PORT 1 7 RESET SERIAL IN 10 SERIAL OUT 11 INTERRUPT 0 12 INTERRUPT 1 13 TIMER COUNTER 0 TIMER COUNTER 1 15 WRITE 16 READ 14 CRYSTAL 1 18 CRYSTAL 2 19 GROUND 20 400b WH When the contacts of the relay are open the relay acts much like a tele phone hookswitch It electrically re moves the telephone instrument from across the line simulating put ting the handset back in its cradle After the 2 second off period has timed out the 8031 re energizes the relay This action closes the contacts and re establishes connection of the instrument to the phone line At this time a dialtone is once again re stored At the conclusion of these predetermined events the 8031 re arms itself The Call Restrictor is designed to be placed on a line that uses only tone dial type instruments The 8031 responds to the dual tone multi fre quency abbreviated DTMF see Dual Tone Multi Fr
46. meter will indicate the correct f stop for proper exposure as a func tion of film speed It will result in cor rect exposures saving you time and always fire the heads to discharge the capacitors and trigger circuits before stowing your gear Do this by firing the system with the TEST button and DPL20 Dancing Plasma to Music and Sounds Assembled 79 50 5 5 SECURITY AND PROTECTION DEVICES immediately switch off ac power film Shutter speed doesn t have any ITM10 100 000 Voit Intimidator up to 20 Assembled 129 50 1 i 1 7 Invisible Pain Field Blasi Wave Gen Assembled If at any time you must gain access ef fect on exposure because the flash PSP4K Phasor Sonic Blast Wave Pistol Kit to the interior of the power pack ex is only about a millisecond in dura LIST10 Infinity Xmtr Lislen in Via Phone Assembled 199 50 4 2 2 TAT30 Automatic Tel Recording Device Assembled 24 50 ercise extreme caution Bear in mind tion With focal plane shutters how VWPM7K 3 Mi FM Auto Tel Transmitter Kit FMV1K FM Voice Transmitter Kit HOD1K Homing Tracking Beeper Transmitter Kit EASY ORDERING PROCEDURE TOLL FREE 1 800 221 1705 or 24 HRS ON 1 603 673 4730 or FAX IT TO 1 603 672 5406 VISA MC CHECK MO IN US FUNOS INCLUDE 10 SHIPPING 100 00 amp UP ONLY ADD 10 00 CATALOG 1 00 OR FREE WITH ORDER INFORMATION UNLIMITED P 0 BOX 716 DEPT ME 9 AMHERST NH 03
47. mind when building the transmitter keep all wire runs and component leads as short as possible and mount the power supply on a separate board A suggested layout for the main board is shown in Fig 9 The 01 02 preampison theend the U3 modula tor is in the center and the U4 oscilla tor is on the left The output section Q1 through Q4 D1 through D4 and their support components are at the far left and along the top of the board The modulator is fed from both sides and the output is at a cor ner of the board away from the mi crophone preamplifier circuit Begin assembly by mounting into place the four IC sockets Do not plug the ICs into the sockets until you re directed to do so Then mount the other components in the loca tions shown for them Some resistors and the diodes mount on end to con serve board space Refer to Fig 7 Wire together the components Take care in making connections to the IC sockets elec Say You Saw It In Modern Electronics oo COGEUHELUPOESECENEPNENUSS SE 4 u L trolytic capacitors diodes and tran sistors The microphone and signal inputs antenna output GAIN control R21 and MIC SIGNAL selector switch 51 mount off the board Provide solder post pins on the board for circuit ground 15 and 15 volts the microphone and sig nal inputs antenna output MIC SIG NAL selector switch and GA
48. of the C socket pin 20 of the C2 socket pins 26 and 28 of the C3 socket pins 16 of the C4 sock et pins 1 27 and 28 of the C5 sock et pin 18 of the C6 socket and pin 14 of the C7 socket At all locations your reading should be 5 volts If you fail to obtain the proper reading at any indicated point power down the project by unplugging its transformer from the ac outlet Cor rect the problem before proceeding When you are certain that every thingis okay with your wiring power down the project and wait a minute or so for the charges to bleed off the electrolytic capacitors in the power supply Then plug the DIP ICs into their respective sockets Make sure each is properly oriented and that no pins overhang the sockets or fold un der between ICs and sockets If you have an oscilloscope you can make an operational check of the Call Restrictor as follows Clip the common ground lead of the scope to circuit ground in the project and the lead of the scope to pin 11 of CI Power up the project by plugging its transformer into an ac outlet and observe the scope display If everything is okay you should ob serve pulses appear on the CRT screen These pulses last for only about 0 5 second their presence in forming you that the program data in the EPROM is being read by C1 If you fail to observe pulse activity on the screen of your oscilloscope power down the Call Restrictor and
49. pages 16 95 focuses on uses for transconduc tance and Norton op amps OTA projects include direct coupled differential am plifier agc amplifier low power Schmitt trigger four quadrant multiplier ran dom music maker Norton amplifier projects include wide bandwidth high gain amplifier under voltage detector low and high temperature alarms func tion generator etc All three books provide schematics and operating details for circuits dis cussed Though no pc guides are given the projects presented are basically sim ple and can easily be built using tradition al point to point wiring techniques From Modern Electronics author Steve Sokolowski comes The Talking Telephone Tab Books soft cover 337 pages 17 95 a book sure to excite the telephone project enthusiast Its title is also the name of the main featured proj ect and 14 other interesting projects are provided as well some of which appeared in the pages of Modern Electronics as construction projects Among the other projects featured are English style two tone and melody ringers high tech mu sic on hold adapter dialed digit dis plays digital telephone lock talking tele phone ringer and synthesized speech for your telephone How it works schemat ics parts lists construction including pc and component placement guides and installation details are given NEW LITERATURE DSO Application Guide An Application Guide titled
50. parts suppliers and surplus dealers among others A very simple strain gage can be made by cementing a length of conductive foam plastic to an object that is subject to bending compression or expansion The resistance of the conductive foam will in crease when the foam is stretched and de crease when it s compressed For repeat able results it s essential that connec tions to the foam be stable Optical Strain Gages Many types of strain gages can be made with the help of optoelectronic compo nents and optical fibers For example simple displacement sensors can be made by placing between the arms of a slot type optoisolator a vane attached to the object in which strain is to be detected If the vane has an angular profile and if it s carefully positioned the slightest move R1 R3 1K 2 2 SEE TEXT RS Loo Vour RS R47 STRAIN GAGE BALANCE Fig 6 Schematic details of a strain gage amplifier circuit Say You Saw It In Modern Electronics DIGITAL VIDEO STABILIZER ELIMINATES ALL VIDEO COPYGUARDS While watching rental movies you will notice an noying periodic color darkening shift un wanted lines flashing or jagged edges This is caused by the copy protec tion jamming signals em bedded in the video tape such as Macrovision copy protection DIGITAL VIDEO STABILIZER complete ly eliminates all copy protec tions and jamming signals
51. plied to the tube this trigger pulse ionizes the internal xenon gas so that the capacitor in turn discharges through the very low resistance of the ionized gas and produces a light pulse of very short duration Nearly 500 volts dc appears across the flash tube and cable conductors when the storage capacitor is charged The trigger capacitor charges to about 150 volts which also appears on the third cable conductor Within the head housing when the tube is fired the voltage at the secondary of the trigger transformer is a pulse with a magnitude of at least 4 000 volts and may even approach 10 000 volts with certain transformers Conse quently component layout and cable type should be selected with these voltages in mind Fit the flash head with adequate hardware to permit it to be attached to a standard light stand A tilt head is particularly useful for aiming the flash to direct light in a specific direc tion during use Power Pack This part of the sys tem requires construction from scratch Here we give you a choice between two versions of power pack to build bare bones and a more elaborate design both of which can power up to three flash heads The major difference between the two de signs is the amount of loading each applies to each flash tube when the tubes are fired in parallel When using multiple flash heads powered by a common power pack Say You Saw It In Modern Electronics each flash tu
52. power supply is also avail able to the prototyping station to be used with experiments that draw less than 100 milliamperes of current You can add a separate power supply to the prototyping station when build ing projects that draw more than 100 milliamperes Computer Platform Bus When you conduct experimental computer projects you want all 8088 CPU sig nals plus the 8155 I O signals at the prototyping station The second 40 pin connector ties the address data control and chip select signals to your prototyping station This per mits you to perform experiments us ing the 8088 microprocessor and its RAM ROM and 8155 I O as the host All you must add is the experi ment components and the program Power Supply This project re quires a power supply capable of de livering 5 volts at ampere and Over 75 000 active amateurs in over 125 countries throughout the world read and enjoy a different kind of ham magazine every month They read CQ It s more than just a magazine It s an institution SUBSCRIBE TODAY 36 MODERN ELECTRONICS March 1991 12 volts at 100 milliamperes ME o o Mr c 8 5 3 a 8 0 Ay o s 24 85 vo DN TUN gt 293 29508 gt gt gt 1 29 42 20 N 2 e 3 z 5 amp a 8 2 x 8 gt gt gt e 2 az
53. present To understand what is meant by side bands visualize the audio spectrum in terms of frequency This can be re presented in a graphic manner in much the same way as audio equip ment frequency response curves are presented Speech can be simplified into a fre quency curve that has a hump cen tered around 5 kHz as in Fig 1 AI though the hump appears to be sym metrical in Fig 1 A it isn t It s shown like this for simplicity As Shown speech consists of a range of frequencies with greatest concentra tion in the middle of the range and a tapering off at both ends of the curve A phantom curve that depicts neg ative frequency is also shown in Fig 1 Negative frequency is an im portant concept in gaining under standing of the modulation and trans mission process A spectrum analysis of the human speech reveals a range of frequencies that can be divided into fundamental carrer Modulating ii N Detected Signal Filtered Signal 27 Fig 2 Representations of modula tion transmission detection and fil tering of a signal March 1991 MODERN ELECTRONICS 39 Fig 3 A simple AM detector circuit arrangement parts as a summation of sinusoids Mathematician Fourier hypothe sized that any continuous function can be represented as a summation of sine waves starting at a fundamental frequency and adding to it higher fre quencies harmonics which a
54. rms at 22 Hz The input and all outputs are made via standard RJ 11 modular jacks Ring loading is rated at 5 0 REN The unit measures 6 L x 4X W x 2 H and weight 1 lb 10 oz CIRCLE NO 8 ON FREE INFORMATION CARD SMT Pick Up Pencil OK Industries offers a safe and easy way of handling static sensitive com ponents with its new VP 150 Series vacuum pick up pencil The pencil is made from static dissipative materi als and offers two user selectable vacuum deactivation modes Contin uous deactivation of the vacuum is accomplished either by removing a finger from a bleed hole in the hand piece or using a foot operated switch The VP 150 can be used with OK In dustries SMT 80 board holder and SMT 815 component carousel 176 CIRCLE NO 9 ON FREE INFORMATION CARD Wireless Car Alarm Midland International s new Model 73 375 provides a motion detector and vibration sensor for automotive security Powered from a vehicle s cigarette lighter socket or a cord that connects directly to a vehicle s elec trical system it also features an emergency back up power system battery optional so that disconnec tion of the alarm from the vehicle au tomatically sounds the alarm This alarm detects motion and sounds the alarm if an attempt is made to tow or push the vehicle in which it is installed It also detects shock conditions such as glass break age When the alarm triggers it sounds dual 110 dB sirens for 9
55. the camera you R use if the flash is mounted on it you get very restrictive illumination because light aimed at your subject from the same axis as the lens can produce flattening and very unflattering front light This flash on camera arrangement is also the cause of red commonly seen in color photos of people For effective photography lighting you need more than one light sourcein lo cations that are off camera Though use of a flash gun with a flash head that can be tilted upward to bounce light onto the subject pro vides a bit of improvement it isn t a good solution Light reflected bounced off the ceiling onto your subject from a direction may be more flattering but the intensity of the light that reaches your subject is con siderably reduced when compared to direct flash intensity Consequently unless you use a fairly powerful flash gun the light falling on your subject may be too weak to provide adequate exposure without a fast lens For effective portrait photos what you really need is a multiple head flash system like the triple head de sign described here Our Triple Head Flash System is designed to meet three important criteria for good in door studio quality photos One is the modeling light which is the dom inant light that establishes the direc tion of principal illumination and is seldom located at the lens axis It de fines butterfly Rembrandt 45 etc typelight Next is fi
56. the next 12 months and may resign at any time thereafter Ironclad No Risk Guarantee If not satisfied with your books return them within 10 days without obligation Exceptional Quality Ail books are quality publishers editions especially selected by our Editorial Board MDNE391 A shipping handling charge and sales tax will be added to all orders 3138 60 00 Counts as 3 S IMPROVING TY SIGNAL RECEPTION MASTERING ANTENAS AAR SWEA atii 2970P 16 95 ANTENNA HANDBOOK FILTER DESIGN 3355 26 95 Counts as 2 162 HOMES REMOTE CONTROL Sent CTS gt Bes P Mein ar 2735P 16 95 gem ta HOME ELECTRONICS FIX IT BOOK 2790P 14 95 2883P 17 95 card is missing use this address to join ELECTRONICS BOOK CLUB Blue Ridge Summit PA 17294 0810 Publishers Prices Shown 1991 ELECTRONICS BOOK CLUB LEARN VCR CLEANING MAINTENANCE REPAIR EARN UP TO 1000 A WEEK WORKING PART TIME FROM YOUR OWN HOME Secrets Revealed NO Special Tools or Equipment Needed THE MONEY MAKING OPPORTUNITY OF THE 1990 S IF you are able to work with Common small hand tools and are familiar with basic electronics i e able to use voltmeter understand DC electronics IF you possess average mechanical ability and have a VCR on which to practice and learn then we can teach YOU VCR maintenance and repair FACT up to 90 of ALLVCR malfuncti
57. toll numbers and any attempt to access them by dialing 0 By Steve Sokolowski The Modern Electronics Computer Experimenter Lab Part 3 Adding a combination Digital Signal Generator and 8088 microprocesor Computer Experimenter Platform to the Dual Channel Function Generator By Martin Meyer AM Radio Transmission How AM radio transmission works and mini power AM transmitter you can build and use for experimenting By Bob Mostafapour Triple Head Photo Flash System Gives amateur photographers the advantage of multiple source studio lighting systems for shooting professional quality portraits By Maurice P Johnson COLUMNS Electronics Notebook Electronic Strain Gages By Forrest M Mims III PC Capers Calendar Creator Plus and Top Priority Personal Information Manager Software from Power Up By Ted Needleman Solid State Devices A SCSI II Adapter Ruggedized SRAM and BurstRAM By Joseph Desposito DEPARTMENTS Editorial Printed Circuits By Art Salsberg Letters Modern Electronics News New Products Books amp Literature Advertisers Index 4 MODERN ELECTRONICS March 1991 EDITORIAL STAFF Art Salsberg Editor in Chief Alexander W Burawa Managing Editor Dorothy Kehrwieder Production Manager Emily Kreutz Production Elizabeth Ryan Art Director Barbara Terzo Artist Pat Le Blanc Florence V Martin Linda Romanello Phototypographers Hal Keith Ilustrator Bruce Morgan Photograph
58. you CIE can get you started with core lessons applicable to aif areas of electronics As you advance CIE makes job opportunities available to you through the bimonthly school paper The Electron Practical Training At Your Own Pace Through CIE you can train for your new career while you keep your pres ent job Each course allows a gener ous completion time and there are no limitations on how fast you can study Should you already have some electronics experience CIE offers several courses which start at the intermediate level State Of The Art Facilities amp Equipment In 1969 CIE pioneered the first elec tronics laboratory course and in 1984 the first Microprocessor Laboratory Today no other home study school can match CIE s state of the art equipment And all your laboratory equipment is included in your tuition cost There is no extra 6 1 5 yours to use while you study at home and on the job after you complete your course Earn Your Degree To Become A Professional In Electronics Every CIE course you take eams you credit towards the completion of your Associate in Applied Science Degree so you can work towards your degree in stages And CIE is the only school that awards you for fast study which can save you thousands of dollars in obtaining the same electronics education found in four year Bachelor s Degree programs Write for details today Send For Your Cat
59. 0 422 0525 708 658 2121 EB Nolllinoisorders Hours 8 00 am 5 00 pm central time kx x PRESENTING A CABLE TV DESCRAMBLERS STARRING x d amp 4 JERROLD HAMLIN OAK AND OTHER FAMOUS MANUFACTURERS FINEST WARRANTY PROGRAM AVAILABLE LOWEST RETAIL WHOLESALE PRICES IN U S ORDERS SHIPPED FROM STOCK W ITHIN 24 HRS ALL MAJOR CREDIT CARDS ACCEPTED FOR FREE CATALOG ONLY 1 800 345 8927 FOR ALL INFORMATION 1 818 709 9937 PACIFIC CABLE CO INC 73252 RESEDA BLVD DEPT 1208 RESEDA 91335 Cable TV Descramblers If you find a better deal we ll better our deal Jerrold Hamiin Oak Sclentific Atlanta Zenith Ask about our extended warranty program COD Visa M C welcome Free Call Free Catalog Video tech 800 562 6884 3702 S Virginia St Ste 160 304 Reno NV 89502 CIRCLE NO 20 ON FREE INFORMATION CARD March 1991 MODERN ELECTRONICS 81 NEW PRODUCTS DSP Head Unit The interior of a car can be trans formed into a variety of listening en vironments with Pioneer Electronics USA Inc s Premier KEX M900 three source head unit with built in digital signal processor The DIN size unit is said to bethe first to com bine DSP capability with CD con troller an AM FM receiver and a cassette tape player DSP creates digital sound field control and provides digital equaliza tion It permits selection of st
60. 0 sec onds and then automatically resets The alarm can be turned on and off with an ultra miniature key chain remote control device that operates from up to 30 feet away One beep sounds to confirm that the alarm is armed and two beeps indicate when it is disarmed The remote controller can also be used as a switch 14 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics The remote controller has 2 186 user programmable codes The alarm unit is equipped with an external siren jack for use with a remote siren Shock resistant LEDs light to indi cate when power is on and the alarm is armed the armed LED pulses to get attention and serve as a visual de terrent to potential thieves CIRCLE NO 19 ON FREE INFORMATION CARD Specialty Microphone Audio Technica s Model PRO 35R remote power condenser micro phone is said to be ideally suited to close miking applications for high intensity musical instruments to pro vide undistorted output in sound fields as great as 141 dB SPL It in cludes an AT8418 UniMount in strument mount that surrounds the microphone with foam to eliminate instrument noise and provide wind screening A rubber buffered spring clamp securely mounts the micro phone without marring the surface of the instrument and a gooseneck per mits precise microphone placement for optimum sound pick up The PRO 35R comes with a per manently attached 5 9 foot min
61. 00 MI CRO THinc BOX 63 6025 MARGATE FL 33063 1 305 752 9202 VHS VCR Repair Solutions Sets I II IV V VI Each contains 150 symptoms and cures updated cross reference chart free assistance 11 95 each all six 59 95 Eagle Electronics Box A 52053 Locks Lane Granger IN 46530 VIDEO Training Tape Mechani Problem Diagnosis SMPTE standards explained shows how professionals diagnose mechanical problems on VCR s 65 minutes 24 95 includes shipping in U S A Send check VISA or M C TENTEL 4475 Golden Foothill Pkwy El Dorado Hills CA 95630 ELECTRONICS SPEAKER enclosure design booklet Equa tions not found elsewhere crossover coilwrap ping information 3 00 Dennis Lance Ent P O Box 5986 Station L Edmonton AB Canada T6C 4G5 CALLER ID displays phone number of person calling you after first ring stores phone num bers of 14 recent calls 89 95 ppd EDE P O Box 337 Buffalo NY 14226 716 691 3476 KINETIKITS from KINETICO electronic kits outputting light or sound Free catalog KINETICO P O Box 1634 NY NY 10114 0508 MINIATURE FM TRANSMITTERS Track ing Transmitters Voice Disguisers Bug De tectors Phone Devices More Available in kits or assembled and tested Catalog 2 00 XANDI ELECTRONICS Box 25647 B9 Tempe AZ 85285 5647 SURVEILLANCE COUNTERSURVEIL LANCE devices catalog Cameras bug detec tors video camera detectors tran
62. 00 items including loads of name brands 3 000 RCA GE parts alone and the largest selection of Japanese semiconductors in the country But as an MCM customer you ll enjoy even more like a friendly well trained sales staff technical assistance when you need it and a GIGANTIC INVENTORY that lets us ship more than 98 of all orders within 24 hours So what are you waiting for Call TOLL FREE 1 800 543 4330 NOW to get your FREE ONE YEAR SUBSCRIPTION to the CIRCLE NO 45 ON FREE INFORMATION CARD March 1991 MODERN ELECTRONICS 7 MCM Electronics Catalog SOURCE NO ME 58 MODERN ELECTRONICS NEWS JAPAN RADIO GOES DIGITAL Some radio listeners in Japan were recently treated to digital broadcasts from a satellite It s called Radio GIGA transmit frequency is measured in gigahertz To receive its digital signals requires having a small satellite dish and a special tuner that s attached to a TV set Furthermore the commercial free broadcasts will be scrambled in April requiring purchase of a decoder 230 plus 5 30 per month For this one will get 24 hour broadcasts of mostly relaxing music It s claimed though that sound quality is equivalent to that of an audio compact disc with no static or hiss to mar reception The broadcaster Satellite Digital Audio Broadcasting hopes to have 700 000 paying customers within two years Such expectations aren t as high as you might think because there are few rad
63. 031 that the storage capacitors may have potentially injurious charges on them So exercise care when the unit is open Discharge all capacitors be fore you do any internal testing ever speeds must be slow enough to ensure that the curtains are fully open when the flash does fire This means you must use X sync usu ally at 4 second or slower ME 58 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics ELECTRONICS NOTEBOOK m Electronic Strain Gages By Forrest M Mims III The strain gage is an electronic transduc er that senses physical expansion com pression or bending of a surface A strain gage is usually bonded directly to the sur faceit s designed to monitor Additional ly some strain gages can monitor the dis placement of a surface from a short dis tance away Many types of strain gages are used for dozens of different applications Before we discuss several ways you can make strain gages of your own let s find out how they re used and examine some typi cal kinds of commercial strain gages Applications Among the most important applications for strain gages is continual monitoring of mechanical structures subject to com pression expansion flexing and torsion Shown in Fig 1 is a pictorial representa tion of each of these kinds of strain De pending on their location in the structure steel girders in a highway bridge may be subject to either compr
64. 1 is used to C2 Pulsing allows the low order address information to passthrough on pins 2 5 6 9 12 15 16and 19 of C2 while data informa tion is stopped Along with the en abling pulses from C4 and the read or write signal from 1 separate ad dress and data bus information is de livered to their appropriate chips at the proper times Examining sections A and B of Fig 3 you can readily see that all ad dress and data lines are wired in par allel with C3 If not for the enabling March 1991 MODERN ELECTRONICS 21 50 Port 1 8 1 1 3 3 4 4 5 5 6 6 7 7 8 18 163 18 8031 17 6264 15 T a XTALL B UE e 32 18 19 38pf B 33 L Ab 17 16 aL ILLI 35 34 el 12 3 anae 7 31 6 gM oo 5 39 2 29 38 Reset 3 29 1 16 V G 2 2 22 RD 164 1415138 50 Addr 89009 Addr To ICS Pin 28 Addr BEBOSH To IC Pin 1 Fig 3 Complete schematic diagram of Call Restrictor is shown here in five parts labeled A through E Fig 3 A 22 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics Ri 10K x 8 10103 Pin 11 Pin 12 Pin 13 Pin 15 Pin 16 Pin 1 Pin 18 Pin 19 Pin 2 Pin 23 Pin 21 Pin 24 Pin 25 Pin 3 Pin 4 Pin 5 To 104 Pin 15 Addr Oh To Pin 29 pulses created by C4 data and ad dress conflicts would occur between IC4 and 1 5 Pull up resis
65. 15 South 46th St Phoenix AZ 85044 5399 Phone 602 968 6231 FAX 800 366 9662 CIRCLE NO 47 ON FREE INFORMATION CARD AMAZING SCIENTIFIC amp ELECTRONIC PRODUCTS LASERS AND SCIENTIFIC DEVICES VRL2K 3mw Vis Red Laser Diode System Kit LLIS1K Laser Beam Bounce Listener Kit 199 50 LHC2K Visible Simulated 3 Color Laser Kit 44 50 107 40 Watt Burning Cutting Laser Plans RUB4 Powered Pulsed Drilling Laser Plans 16040 1 to 2mw HeNe Vis Red Laser Gun Assembled 199 00 LLS1 Laser Lite Show 3 Methods Plans i SD5K in the Dark Kit EML1K Electromagnetic Coil Gun Kit MCP1 Hi Velocity Coil Gun Plans LEV1 Levilating Device Plans EH1 Electronic Hypnotism Techniques Plans 10 00 HIGH VOLTAGE AND PLASMA DISPLAY DEVICES mp CH rcs NN E a Cautionary Notes Storage capacitors must be able to hold a high energy charge and not leak or discharge over long periods of time In ternal losses must be very low These de sirable factors for a good storage capa citor also contribute to making it a po tentially lethal device Even a comput er grade electrolytic capacitor can hold its charge for many hours even days Another mark of a good capacitor is low internal resistance which means that there s nothing internal to limit the discharge current if the terminals are shorted together The factors that g
66. 445 RF Frog 100 450 TF More i o RE AM Modulation ol KHz CALL FOR Contains all the desired leatutes lor doing experiments Vanable RF output Features short circuit protection all supplies SPECIAL PRICING or FM capability Soldering Station 10MHz Oscilloscope Temperature Probe Color Convergence Generator Tempergture Controlled 4 T 96 200 1 3000 Pu 110 13 5275 29 95 7 TOMHz DC or AC Sericondudor S rJ Tnggered Sweep ppm inest in the industry Vert amp Hor protect 10 rock steady patterns 69 95 Reads Vots amp Freq aiptalmutmeters S8F302F dt LCD AC Current Meter LEARN TO BUILD AND PROGRAM 814010 2 COMPUTERS WITH THIS KITI 69 95 if INCLUDES Ports Assembly and Lesson Manual Model 1000 Amps MM 6000 Date amp Peak hold 7 47 ohm to 1M amp 100K pot ran Des Case 9620 Capactor Blox Fully regulated end rout protected 129 00 470 to 10 575 without meters 39 95 Digital Triple Power Supply XP 765 GF 8016 Function Generator Staring trom scratch you build completo system Our Micro 249 tramer loaches you to wnte RAMs ROMS and run 8 8085 microproces 0 20V at 1A 249 which uses machine language IBM PC You wii write the 0 20V at 1A
67. 6 100 volt 1 ampere silicon rectifi er diode D7 400 volt 1 silicon rectifi er diode SCR1 200 volt 1 ampere or moresili con controlled rectifier Capacitors 1 8 500 volt electrolytic C2 C3 C4 600 or 800 4F 500 volt computer grade electrolytic C5 22 nF 50 volt electrolytic 0 22 0 400 volt paper Resistors 10 tolerance R1 R2 R3 1 000 ohms 10 watt wire wound R4 1 megohm 1 watt carbon R5 470 000 ohms 1 watt carbon R6 533 000 ohms for 1 mA meter movement 5 3 megohms for 100 4A movement R7 10 ohms watt carbon R8 180 ohms carbon R9 470 ohms 4 watt carbon R10 5 000 ohms 10 watt wire wound R1I R12 R13 2 megohms 2 watt car bon Miscellaneous F1 3 ampere slow blow fuse F4 100 watt second 450 volt flash tube with suitable reflector and hous ing GE FT118 or similar 11 6 3 volt ac panel lamp M1 1 mA or 100 4A meter movement see R6 above S1 S5 Spst toggle or slide switch S2 Sp3t non shorting rotary switch S3 Spst normally open pushbutton switch S4 Sp3t shorting rotary switch SO1 Polarized jack T1 700 volt center tapped power transformer with 6 3 and 5 volt windings see text 4 10 10 000 former Suitable enclosure see text bayonet fuse holder pointer type control knobs for S2 and 54 C clamps for mounting storage capacitors bayonet panel lamp holder sockets for flash head ca
68. 6 R14 L 17 R14 R C7 R 18 C7 L 5V IC7 pin 7 GND 14 5V IC8 IN C8 D2 K D4 K COM C8 C9 C10 B D1 A D3 A GND bus OUT C9 C10 T bus Q1 Collector RYI coil B Base R15 R Emitter GND coil T 5V contact 1 RY2 coil T contact 2 CS L red instrument line RY2 coil T Red telephone line coil B Green telephone line coil B C6 L green instrument line contact 1 GND C5 R9 L C6 RIO L Note Numbers in parentheses are pin designa tions for IC specified and letters in parentheses indicate A anode diodes only K cathode diodes only L left R right T top and B bottom IC pins to which no connections are made are not listed one end panel and a pair of entry holes through opposite ends of the enclosure for the telephone line and the cable that goes to the telephone instrument s to be monitored Final ly drill a small hole near the tele phone line and instrument cable en try holes If you drilled any holes through metal deburr them to re move sharp edges and line the entry exit holes with rubber grommets Mount the circuit board assembly March 1991 MODERN ELECTRONICS 71 Say You Saw It In Modern Electronics Dual Tone Multi Frequency Tone dial telephones produce a special kind of DTMF an acronym for Dual Tone Multi Frequency signal devel oped by Bell Laboratories more than 25 years ago DTMF uses pairs of eight specially selected audio tones t
69. 7 914 232 3878 CIRCLE NO 28 ON FREE INFORMATION CARD CONSOLIDATED ELECTRONICS Get two of the most valuable electronic catalogs ever These 2 catalogs contain over 16 000 hard to find electronic parts amp 2 equipment VOL features 112 pages of high quality test equipment VOL Il features 144 pages of electrononic parts tools amp cross references Send 5 check or money order or call today amp use your VISA or MasterCard 1 800 543 3568 CONSOLIDATED ELECTRONICS INCORPORATED 705 WATERVLIET AVENUE DAYTON OHIO 45420 2599 FAX 1 513 252 4066 TEL 1 513 252 5662 TELEX 288 229 COMPUSERVE 76057 3347 EASYLINK 62850013 CIRCLE NO 21 ON FREE INFORMATION CARD 4 VOLUME 1 PAR SONNE EE March 1991 MODERN ELECTRONICS 57 All the tools amp test equip ment you need for hobby or work Electrical electronics computers communica tions sound systems all the tools meters and other equip ment you need to doa professional job Top technicians and field service personnel prize their Jensen tool kits Our new 232 page Master Catalog will show you why You ll discover hard to find items the latest high tech developments soldering stations wire amp cable accessories and many more quality products you want and need Send for your free copy today 4 JENSEN TOOLS INC a 78
70. 900 for dating sports and what have you as well as 976 horoscope and tarot cart reading services and credit card applications services Prices for using these services which appear on your monthly telephone bill range from 75 cents to a whop ping 30 for a call that can last as short as 2 minutes If you are fed up with high month ly telephone bills resulting from the abuse of dial it services by say your children fight back with our Tele phone Call Restrictor When this computerized device senses any out going call beginning with 1900 or 976 it disconnects the telephone in strument from the line In addition it also detects when the 0 button on the instrument s keypad is pressed to prevent operator assisted connec tions to these services The Call Restrictor installs be tween any line to which telephone in struments are connected and the tele phone line It does not interfere with normal calling You can easily re coup its modest cost in just a month or two of lowered phone bills Project Overview The Call Restrictor makes use of an inexpensive 8031 controller chip This chip is basically a computer squeezed into a 40 pin package whose pinouts are detailed in Fig 1 The 8031 must be told what to do In the case of the Call Restrictor the 8031 must monitor the telephone line to detect dialing If the number being dialed starts with 1900 976 or 0 the 8031 must immediately disconnect the telephone
71. AND NEW 90 Day Warranty Model 3584 IBM 5182 Demos 299 200 CPS Wide Carriage Color Printer PANASONIC KXP 1124 New 279 24 192 CPS 63 NLQ Narrow Quantity TOSHIBA 301 Below Cost New 229 Laptop Printer 24 Pin 180 CPS SEIKOSHA SL 80AI 229 24 Pin Narrow 135 CPS 54 NLQ 3 165 24 149 RITEMAN by C ITOH 119 120 CPS 60 CPS Exp Narrow Carriage 6 159 Over 24 CALL ONLY 12 155 AT amp T FULL PAGE SCANNER AT amp T CRT 327 12 TTL wm Includes IBM Compatible Interface Card Tilt amp Swivel Black amp White Monitor BRAND NEW The Includes AT amp T PAGE POWER SOFTWARE 90 Day Warranty INCLUDES AT amp T 1024 Card gt Draw Scan and Fax Package List 1390 gt SCANNER poa Includes Microsoft Runtime Windows Resolution Works on All IBM AT XT s amp Compatibles 5 1 1 9 has BRANDNEW 200 DPI Full Page 400 DPI Half Page 6 115 12 109 24 105 Over 24 CALL ONLY Half Tone feature for Photographs SAVE OVER FREE 1 Year Warrant NCR 15 Green TTL 75 aie ee with NCR Monitor Card 640x400 List 1190 P9 ONLY 7 59 1 YEAR Q Q Quantity Discounts Available ave over Warranty 438 Dealer Inquines invited x Electrified Discounters sso erm UAE 800 678 8585 2m 1066 Sherman Avenue Catalog Sent with All Orders Hamden CT 06514 Customer Service amp Technical Support eer
72. DEALS AT amp T 40 MB Tape Backup Kit MINISCRIBE 3675 62MB RLL 5 1 4 NEW MINISCRIBE 8450 40MB ALL 3 1 2 NEW 199 SEAGATE ST 138A 32MB ALL 3 1 2 199 eSEAGATE 5 4051 40MB 8189 SPEED UP BOARD DAC EASY BREAKTHRU 286 Make Your 8088 Computer A 80286 Computer 12 MHz SPEED UP BOARD For Your 8088 Computer SAVE 75 BRAND NEW IBM PC XT or Compatible BRAND NEW 1000 FASTER THAN A REGULAR PC Replace Your Old CPU with an Intel 80286 Microprocessor Inciudes a 80287 Math Co Processor 510 with 16K Cache Memory and Zero Wait Azcess Easily Installed in 5 Minutes Sottware Compatibility is Virtually UNLIMITED Full Matr Warranty and Technica Support 199 299 Monitors Amdek Apple AT amp T Goldstar Hitachi IBM Magnavox Mitsubishi NEC Pacard Beil Panasonic Princeton Graphics Samsung Seko Sony Tatung Zenith Full HT MINISCAIBE 84 38 30 8 811 3 1 2 NEW SEAGATE ST 238 30MB RLL 5 1 4 1 2HT TANDON TM 262 20MB MFM 3 1 2 WESTERN DIGITAL MFM XT Cont w Cables 49 RLL Controllers tor XT and AT s Available CALLI MINISCRIBE Warranty 6 Months NEW DRIVES Seagate amp Tandon Warranty 90 Days OEM Pulls QUANTITY PRICING AVAILABLE CALLI Printers ALPS Apple Brother Canon Citizen C ITOH Diablo Diconix Kodak Epson Fujitsu Genicom
73. HAND HELD SCANNER FROM LOGITECH Edit scanned images with advanced graphic tools in PaintShow Plus included with ScanMan Plus Scan directly to the MS Windows clip board TIFF or PCX files with ScanMate a LOGITECH SERIES 9 SERIAL MOUSE 69 50 SERIES 9 SERIAL PS 2 MOUSE 74 50 SERIES 9 BUS MOUSE odes 79 50 Catchword OCR Pa mua 9128 50 PS2 Version Scanman 219 50 256 Grey Level Scanman 339 50 MAC Version Scanman utility that will speed up your hard disk TRACKMAN and improve its reliability D High Resolution Stationary Mouse GET combines the scattered file segments on your disk Gsm is into complete sequential files thereby increasing TrackMan is a revolutionary new input device H YOUR disk speed and efficiency This will allow your hard that combines the advantages of both a MARDDIR and a trackball UP TO your hard disk will not only respond quicker it will SPEED also last longer 4950 easy to use 6 00 Shipping Ergonomical design for quick comfortable action al High speed autofire both hase and T handle grip buttons X amp Y axis trim adjusters JS 606 19 50 Switchable buttons 5 j Auto ce
74. ICD 08559 MARCH 1991 2 95 CANADA 3 95 THE MAGAZINE FOR ELECTRONICS amp COMPUTER ENTHUSIASTS lur Triple Head Photo Flash System 47 E m Build A Digital Signal Generator And Computer Experimenter Platform Mini Power AM Transmitter m Working With Electronic For No License Experimenting Strain Gages Dallas Semi onductor Cyber Card 4M SRAM p 68 An AM Transmitter Project p 38 74820 08559 MICROSCIENCE MODEL 4090 E amp 1 1 1 MB wntormattea 93 MB Formatted Access Speed 18 MS 1 3 1 2 w Frame RLL 4 MS Access Track to Track VOICE COIL DRIVE 1 Year Warranty QUANTITY DISCOUNTS AVAILABLE 5 399 WE WILL TRY TO BEAT ANY FRICE ON ANYTHING FROM ANYWHERE Cal TRULY PROFESSIONAL STAFF WITH A COMMITMENT SERVICE PRINTER POWER MONITOR MANIA GENICOM 5010 LASER PRINCETON GRAPHICS Pages Per Minute 300 DPI Ultra Sync 14 Color Monitor Monito HP COMPATIBLE 1 735 MB of Memory Cards 14 Multisync Ultra Hi Res 28 Dot Pitch e Six Resident Fonts Parallel Serial Includes Toner 800x600 i on BRAND NEW Special Full 90 Day Warranty AMAZING G from Princeton rel Quantity Discounts p Refurbished Mint Condition List 5800 Available 211 IBM VGA COLOR 13 Viewing Area 640x480 31 Dot i IBM 5182 COLOR PRINTER BRAND Model 7544 S01 Heavy Duty Wid
75. IN con trol These will be connected later during the final assembly stages Temporarily set aside the main trans mitter circuit board assembly As shown in Fig 10 the power supply is best wired on two small pieces of perforated board Mount the power transformer bridge recti fier and filter capacitors on the larger of the two boards the remainder of the power supply circuitry on the smaller board Refer to Fig 9 to wire the power supply circuit making sure to observe correct capacitor po larities and regulator and bridge rec tifier pin identifications Use solder posts with which to make interconnections between all three boards and the primary circui try of 1 Label each pin on all cir cuit board assemblies according to its function for easy identification Use any size metal enclosure that accommodates the circuitry and pro vides sufficient panel space on which to mount the connectors and controls see lead photo a suggested layout for the panel Drill mounting holes for the circuit board assemblies and fuse holder and an entry hole for the ac line cord through the rear panel Then drill mounting holes for the connectors and controls through the front panel When done deburr all holes to remove sharp edges Use a dry transfer lettering kit or tape labeler to apply appropriate leg ends on the front panel If you use dry transfer lettering spray two or more light coats of clear acrylic over them
76. INARY DATA LINE FROM 8155 PAS OUTPUT AA HEX 10101010 BINARY Low HIGH DATA LINE 6 FROM 8155 PAG OUTPUT AA HEX 10101010 BINARY DATA LINE 7 FROM 8155 PA OUTPUT AA HEX 10101010 BINARY Low 8155 TIMER OUTPUT SIGNAL TIMER QUT CLOCK INHIBIT SIGNAL 8155 PBO mon op to CSH LON PIN LOW DATA TS LOADED INTO THE REGISTORS 8155 PBL TAKES VALUE OF BIT 7 WHEN BIT 7 BIT 6 5 4 BIT 3 BIT 2 1 TAKES THE VALUE OF BIT 7 WHEN SH LD GOES LOW SL LON GOES LOW OUTPUT LEVELS AT H PIN 8 GNO PIN 16 5 165 FUNCTION TABLE INPUTS SH LON CLK FONCTEON L PARALLEL CONNECTIONS TO DIGITAL SIGNAL GENERATOR H H X NO CHANGE H NO CHANGE NORMAL OUTPUT 7 RTED OUTPUT 3 Fig A Timing details pinouts for address timer out normal out and inverted out and function table for 74LS165 Say You Saw It In Modern Electronics March 1991 MODERN ELECTRONICS 35 ra GA acer am DIN ERA CoU 208801 So A l CUM C COSE Digital Signal Generator 8088 Com puter Experimenter Platform The ROM program initializes the 8251 setting it up to wait for data from the computer The data format selected is 9 600 baud eight data bits and one stop bit The receiver clock signal is generated in the 8155 counter time
77. OF ELECTRONICS ENGINEERING GIE 4251 CYPRESS DRIVE JACKSON MISSISSIPPI 39212 CIRCLE NO 42 ON FREE INFORMATION CARD Telephone Call Restrictor from page 71 To Telephone Line Restricted Telephones Fig 4 Details for installing Cail Restrictor into your telephone sysiem in place using suitable length spacers and machine hardware If the cord coming from the wall mount trans former has a plug on it cut off and discard it Separate the conductors of the cord a distance of 1 4inches Strip inch of insulation from both con ductors Tightly twist together the fine wires in each conductor and sparingly tin with solder Route this cable through one entry hole in the enclosure and tie a strain relieving knot in it about 5 inches from the un finished end inside the enclosure Connect and solder the two conduc tors to the appropriate solder posts Determine where you will mount the project Select a secure location such as your basement where the project is not likely to be discovered This location must be near an ac out let and between the incoming tele ee Se a eS SE 76 MODERN ELECTRONICS March 1991 phone line and any telephone instru ments that are to be monitored see Fig 4 Cut the telephone line at the selected location If necessary use a telephone extension cord to effect installation Remove 1 inch of outer plastic jacket from both cut ends of the tele phone
78. ON CARD Programmable Soldering Station Tamper proof temperature setting quick heating and increased thermal recovery permit a new programmable soldering station from Contact East to consistent high quality soldering with less dwell time on pc boards and heavy ground planes Tip tempera Say You Saw It In Modern Electronics ture can be set on a numeric keypad at less than 2 ohms and leakage volt between 400 and 899 0 9 age is rated at less than 0 6 mV The Once set the temperature cannot be station meets MIL STD 2000 DOD changed without use of a supplied STD 2000 WS 6536E DOD STD programming card A memory sys 1686 DOD HDBK 263 specifica tem permits the iron to be shut off tions The 117 volt ac station comes and turned on without requiringthat with iron holder sponge program temperature be reset each time ming card and 50 watt iron with The housing iron and cord are three conductor line cord 299 made of static dissipative material CIRCLE NO 5 ON FREE INFORMATION CARD for safe use in static sensitive appli cations Resistance to ground is rated ELENCO amp HITACHI PRODUCTS DISCOUNT PRICES uM RSOs Real Time amp Storage Oscilloscopes From HITACHI Mey Compact Series Scopes 74 Continued page 82 The RSO its the new solution View Acquire Test Tronster ond Document Your Wavetorm Data 4 Channel 100MS s Model introductory Price 100MS s 25MS s on 4
79. Optional 100 MHz scope probe with 10 1 attenuator 27 50 3 50 P amp H For Dual Channel Function Genera tor February 1991 Complete set of electronic compo nents including pc board but not power supply or cabinet 69 95 4 P amp H Optional 5 and 12 volt power supply kit one required for both Generators 34 95 4 P amp H Optional black steel cabinet one re quired for combination Function Digital Signal Generator 37 50 4 50P amp H MasterCard and VISA accepted on all orders pulses and square wave trains Programs to produce the signal trains can be written on and down loaded from an IBM PC or compati ble computer or they can be run from fixed programs stored in ROM The programming mode is selected via DIP switch S2 Simple user pro grams can be written using the Debug program supplied with DOS No pro gramming experience is needed for writing these simple programs e The Microprocessor The 8088 CPU U11 is a member of a family of devices that have become the world s most popular series of micro processors If you are going to study any microprocessor this Lab series is an excellent place to start Basic Sys tem architecture and the instruction set is compatible with all newer pro cessors except for memory width address size and added instructions The 8088 microprocessor used in this project is set to operate in mini mum mode That is special control and status signals that
80. PECIALIZE IN DEALER PRICING QTY 1 10 20 Jerrold SB 3 89 00 56 00 48 00 Jerrold Type Tri Bi 119 00 69 00 65 00 Scientific Atlanta SA 3 129 00 80 00 75 00 Hamlin MLD 1200 99 00 59 00 45 00 Oak N 12 Vari Sync 99 00 59 00 58 00 Jerrold 550 Converter 99 00 75 00 68 00 Jerrold 400 DRX 3DIC With Built in 58 3 169 00 109 00 100 00 1 800 327 3407 Call us lor prices on large quantities K D Video PO Box 29538 Mpls MN 55429 CIRCLE NO 41 ON FREE INFORMATION CARD ELECTRONICS NOTEBOOK INSULATING LAYER PANO WIRE CONDUCTIVE PAINT Fig 7 Details for fabricating a piano wire Strain gage ment of the object to which it s attached will change the photocurrent through the phototransistor of the optoisolator Another very sensitive approach is to point the beam from a small laser at a tiny mirror cemented to the surface of the ob ject being monitored The reflected beam should form a spot of light on a fixed white surface some distance away The slightest movement of the object will cause the reflected beam to move notice ably This method is particularly good for detecting torsional strain Optical fibers can be used to make very sensitive strain gages You can quickly demonstrate the sensitivity of an optical fiber as a strain gage simply by injecting the light from a helium neon or diode las er into one end of the fiber The light emerging from the opposite end of the fi ber sho
81. TRONICS 15 NEW PRODUCTS Oxide Penetrating DIP Clip Test clips that penetrate oxide build up on DIP IC leads are now available from Pomona Electronics The six DIP Clip test adapter models function similarly to standard test clips but feature a roughened stainless steel surface coating on their serrated con tacts to provide good electrical con nections on contaminated surfaces These clips provide hands free testing of standard DIP ICs with pin counts from 8 to 40 The 0 04 wide contacts are separated by molded in sulating barriers to permit connec tion to be made on boards without the fear of accidental short circuiting of adjacent contacts The upper contact pins on the clips are 0 025 by 0 028 to accept Wire Wraps or miniature test clips IC jumper cables flat ribbon cables with 8 through 40 pin sockets at one end can also be used to connect these clips with instrumentation Device contacts are tarnish resis tant nickel or gold plated beryllium copper surface coated with the roughened stainless steel Gray glass filled nylon provides insulation for up to 500 volts rms at 1 ampere and up to 20 maximum Models 5649 5650 5692 5693 5694 and 5695 are 8 14 16 20 24 and 40 pin clips respectively 9 70 to 31 each CIRCLE NO 2 ON FREE INFORMATION CARD VHF SWR Analyzer A complete picture of antenna SWR over the entire 2 meter band can be PART 1 DC
82. Wire Wrap technique to wire the circuit use Wire Wrap posts to hold these components except the relays which mount via their own pins in place soldering the component leads to the posts on the top of the board Once the components are in place refer to the Master Wiring List and begin with the JC socket to make your interconnections As you make each wire run trace its path on your photocopy of the schematic in a con trasting pencil or pen color As you 20 properly polarize your connec tions to the socket pins electrolytic capacitors relays and diodes Make sure your connections to the pins of and C2 are correct Note that the latter is the only IC that should be mounted on the board at Continued on page 71 Oo 1 L L LLL A m itid March 1991 MODERN ELECTRONICS 25 Say You Saw It In Modern Electronics Project The Modern Electronics Computer Experimenter Lab Part 3 Adding a combination Digital Signal Generator and 8088 microprocessor Computer Experimenter Platform to the Dual Channel Function Generator By Martin Meyer ast month we gave details for building and using an an alog Dual Channel Function Generator that had room on its pc board for adding a digital signal gen erator which is the subject of this in stallment This add on is a continua tion of a series begun in the January issue with a build it yourself low cost Digital Storage Oscillosc
83. XT cards power supply and keyboard Up to 1 meg on motherboard Disk cache program built into BIOS Quadtel BIOS 7 2 MHz 8 slot 125 8 Mhz 5 or 8 slot 179 10 MHz 5 or 8 slot 179 12 5 MHz 5 or 8 slot 209 16 MHz 5 or 8 slot 299 CALL FOR RAM AND QUANTITY PRICES VANTAGE 20 MHz SX 499 FEATURES The new INTEL 386 SX PA MIE ded RE 599 00 Up to 8 Meg onboard me 48 Hour burn in Shadow Ram AMI BIAS with bullt in Diags PERFORMANCE BENCHMARKS LM 25 4 SI 22 MIPS 3 44 COMPATIBILITY Same as 386 25 22 VANTAGE 386 25 amp 33 MHz CACHE BOARDS FEATURES 48 Hour Burn in Discrete TTL Up to 16 MB 32 bit memory Shadow RAM AMI BIOS with bullt in Dlags PERFORMANCE BENCHMARKS 386 33c Landmark 52 3 5 7 438 999 386 25 Landmark 42 2 5 5 932 5799 Here are just a few of the satisfied customers who saved thousands of dollars for their companies by using D P COMPUTERS to upgrade their systems ALLIED SIGNAL NASA MOTOROLA U S GOVERNMENT BLUE CROSS BLUE SHIELD 801 532 1004 COMPUTERS 801 596 1520 735 So 400 West Salt Lake City UT 84101 We accept COD VISA Mastercard or Personal Checks 30 Day money Back guarantee CIRCLE NO 152 ON FREE INFORMATION CARD Learn to troubleshoot and service today s computer systems as micro Train the NRI way and lear
84. able TV systems with proper authorization from local officials or cable company ofticials in accordance with all applicable federal and state faws FEDERAL AND VARIOUS STATE LAWS PROVIDE FOR SUBSTANTIAL GRIMINAL AND CIVIL PENALTIES FOR UNAUTHORIZED Signed CIRCLE NO 40 ON FREE INFORMATION CARD 89 56 99 79 30 Days Money Back Guarantee Free 16 page Catalog Visa M C COD or send money order to US Cable will Beat Anyone s Price Advertised in this Magazine Dept No Florida Sales CIRCLE NO 43 ON FREE INFORMATION CARD 63 FREE ONE YEAR SUBSCRIPTION Keep abreast of the fastest growing part of the computer industry The EduCALC Catalog features the cutting edge in handheld computation at discount prices Calculators handheld computers Informators and specialty calculators from Hewlett Packard Texas Instruments Casio and Sharp We also have a comprehensive line of accessories books and software for these machines All this at the best prices around You can count on our friendly well trained staff to help you with all your needs and keep you up to date on new products we offer same day express shipping and toll free ordering numbers EduCALC 27953 cabot Rd Laguna Niguel 714 582 2637 CIRCLE NO 30 ON FREE INFORMATION CARD CN p How do 1 get Use the more data free info card K D VIDEO FOR ALL YOUR CABLE TV NEEDS WE S
85. ace of the board Machine the enclosure as needed including drilling a hole for entry of the ac line cord Plan on mounting a carrying handle on the top control panel near the center of gravity Don t drill the holes for the handle until after you ve assembled the pow er pack and can better judge where this point will be Because the power transformer is a bit heavier than the storage capacitors this point will be a bit to the rear of enclosure center Arrange the holes for the POWER in dicator POWER switch and fuse holder at oneend of thecontrol panel and those for the sync cable socket and TEST switch in the other corner The third terminal board will mount on the underside of the panel beneath the carrying handle This 52 MODERN ELECTRONICS March 1991 makes for short leads between capa citors steering components and out put sockets The two rotary switches and meter movement holes should be drilled and punched through the top control panel Switch 55 should mount under the top panel on a small L bracket This Switch isn t an operating control You open it only to insert 10 into the charge path during initial form ing of the storage capacitors You then close it to short out R10 for nor mal power pack operation By mounting components on the three terminal boards you can use point to point wiring to make all in terconnections when you re ready to wire together the components and as semblies Since the curren
86. ad Regular price 650 00 save over 350 NOW Method of Payment 81 Cheque Lh Visa Card Number Name on Card Signature Name Title Organization Address State City Tel THIS OFFER EXPIRES ON MARCH 31 1991 C MasterCard Expiry Date Zip Cl Amex Oms pos 3 5 O L MS DOS 5 25 Special offer x 295 00 shipping and handling 2 of order Evaluation version x 10 00 shipping and handling included Macintosh Amount Total Send order form and payment to Interactive Image Technologies 908 Niagara Falls Boulevard Ltd North Tonawanda NY 14120 2060 Tel 416 361 0333 CIRCLE NO 119 ON FREE INFORMATION CARD Fax 416 368 5799 Communications AM Radio Transmission How AM radio transmission works and a mini power AM transmitter you can build and use for experimenting By Bob Mostafapour ou may have wondered how radio waves are transmitted or why transmission is done in a certain way Or perhaps you shied away from building a radio transmitter because you thought such a project would be difficult re quires a special FCC license and re quires hard to find costly compo nents Actually a radio transmitter especially amplitude modulated one is one of the easiest circuits to build using only readily available low cost components In fact build ing an AM transmitter is a major fo cus of this article An
87. al must be fed through a filter to smooth out sharp edges This is accomplished in the final circuit Project Circuitry Shown in Fig 6 is the block diagram of atransmitter circuit you can build and use for experimental purposes A microphone the low level signal from which is amplified by an on board preamplifier stage or a high level signal that doesn t undergo pre amplification can be used as the modulating signal source The carri er signal comes from a 1 MHz oscil lator for easy tuning of the transmit ted signal on a standard AM broad cast band radio The modulator in this transmitter chops and filters the carrier and mod ulating source signals The final stage buffers the modulator and de livers the output from the transmitter to the antenna As shown in Fig 7 the preamplifi er section is the straightforward two stage UJ and U2 noninverting op amp circuit It s selected by setting S to the alternate position shown The purpose of the preamplifier section is to match the impedance of the micro phone to the impedance of the U3 balanced modulator The gain of each stage in the preamplifier is 30 yielding an overall gain of 900 30 x 30 Two stages were used in the pre amplifier because of the limited gain bandwidth product of inexpensive op amps Though extremely high gain is possible with one op amp a narrower bandwidth would have resulted Capacitors C and C2 in the non inverting amplifier con
88. al of 5 4 volts that s applied to pin 3 of U3 These dc off sets create the envelope needed for DSB C transmission The output of the oscillator at 12 of U3 is clamped at two diode drops of approximately 1 2 volts by DI through D4 The switching mechanism inside U3 is a differential transistor pair that requires only a small voltage to Switch states The smoothing filter that rounds out the sharp edges cre ated by the chopping action is made up of C8 and L2 Without this filter the transmitter would be less efficient because it would waste power on har monic frequencies If you change the carrier frequency you must also re calculate the values of C8 and L2 Capacitor C3 buffers the dc ap plied to pin 1 of U3 and prevents back feeding to U2 Capacitor C7shorts to March 1991 MODERN ELECTRONICS 43 2 Fa eo 2 CT FUSE 120 60Hz BRIDGE C10 2200uF C11 2200uF Fig 8 Schematic diagram of power supply for the AM Transmitter ground high frequencies at pin 4 of U3 allowing proper bias to be ap plied to this pin Bridging resistor R9 sets theinternal bias for U3 Internal ly thetwo emitters of the differential transistor pair meet at R9 Thus the modulating voltage creates a current through R9 and consequently a voltage across this resistor The output of U3 is a current that s fed through R20 to obtain a voltage for transmission The high output imped
89. alog Today Computer Assisted Manufacturing Military Electronics Consumer Electronics Personal Training From A Renowned Faculty Unlike the impersonal approach of large class room study CIE offers you one on one instructional help 6 days a week toll free Each CIE lesson is authored by an independent specialist backed by CIE instructors who work directly with you to answer your questions and provide technical assis tance when you need it grit ED Sc CIE World Headquarters Cleveland Institute of Electronics Inc 1776 East 17th St Cleveland Ohio 44114 YES Please send me your independent study catalog For your convenience CIE will have a representative contact you there is no obligation Print Name Address Apt City State Zip Age Check box for G I Bill bulletin on educational benefits O Veteran Active Duty Mail This Coupon Today a i Area Code Phone No zi VOICE TIMER N m F LOCK m E CLOCKS OFF AL 8 NT Dew Fam A B STEP RESETS NB IF SHIFT AF RF HOUR MINUTE FLOCK A B HF VHF EIE 1MHz 4 ye ZUR the world bands with Kenwood s R 5000 R 2000 and 2 1 Listen in on foreign music news and commentary Monitor local police fire and other public safety services as well as the Mari
90. ance of U3 requires a buffering stage to accomplish transmission The buffering stage is a straightfor ward emitter follower arrangement that has a gain of 1 Since 15 volts is available a class AB circuit was devised Front end transistors and Q2 are con nected as diodes that bias output transistors Q3 and Q4 An antenna not longer than 2 to 3 feet must be used with this transmit ter to assure the broadcasting range is limited to the immediate area Power for the transmitter is pro vided from the 117 volt ac line by the circuit shown schematically in Fig 8 This circuit arrangement provides regulated 15 volts Regulators U5 and U6 reduce the incoming dc volt ages and regulate them to 15 and 15 volts because the biasing volt MOUNTING 95 04 R19 12 d NU R16 UNDER R15 C6 RN 614 812 riz Fig 9 Suggested component layout for main transmitter circuitry on perfor T R6 ms 62 ated board 44 MODERN ELECTRONICS March 1991 ages in various stages is based on 15 volts dc Center tapped power transformer 77 provides outputs for the positive and negative voltages re quired by the transmitter circuitry Construction The simplest approach to construc tion is to wire together the compo nents on perforated board that has holes on 0 1 inch centers using sol dering hardware Use sockets for UJ through U4 Two points to keep in
91. and Turbo Buttons Keylock 3 1 2 5 1 4 and 2 1 2HT 3 1 2 Drive Bays Clock Calendar 1 Year Warranty 14 VGA Coior Montor 1425 Plus with Tit amp Swivel Upgrades Available 101 Keyboard DOS 3 3 with Basic B Siots 1 32 5 16 Bit 2 8 Bit Paralle SeriavClock Calendar 200 Watt Power Supply 80387 Socket Novell Certified 16 Bit 1 Year Parts amp Warranty WARRANTY GOLDSTAR TOLL FREE CUSTOMER SUPPORT LINE Goldstar XT Turbo and 286 16 MGHz Systems are Available CALL 386 25 and 386 33 MHz Systems Available Now CALL SYSTEM OPTIONS SUPER SYSTEM OPTIONS 4 Drive 79 Clock Calendar Card 29 Indi Controller 149 Pa Se ClVGameCard 49 Indi Controller 199 Memory Upgrade to 512K 69 Add 30MB Drive Ind Controller 249 Memory Upgrade to 640K 99 Add a 40MB Drive Controller Speaal AWESOME 0286 TURBO 10 16 MHz Fully IBM Compatible Zero Wait State 512K Installed Full Size Case 200 Watt Power Supply Award BIOS 101 Keyboard Up to 4MB on Motherboard B I O Slots 80287 Socket Reset and Turbo Button Keylock and LEDS 1 YEAR WARRANTY FCC Approved Class Produced by JCC SUPER SYSTEM 8088 1 TURBO COMPUTER SYSTEM rive IBM Compatible System with 256K Memory 1 Halt Height 360K 5 1 4 Drive INSTALLED Dual Speed 4 77 MHz and 10 12 MHz TURBO 256K Instal
92. arge capacity storage capacitor takes longer than a small one to discharge Flash units with electrolytic capacitor values in the hundreds of microfarads produce a flash that lasts a few milliseconds Since the power supply generally runs continuously during a photo session the charging circuit con FLASH HEAD typical of 3 ANODE F A BorC S01 SYNC CONNECTOR attempts to charge the storage capacitors even during the flash dis charge period Therefore the series z charging resistance must also keep the power supply from attempting to keep the flash tube alive by supplying T current directly to the tube If this oc curred the tube would quickly be de stroyed Hence the series charging resistance assures that discharge cur rent comes from only the storage ca 2 pacitor and directly from the power supply li 3 see text 1A i 5V Fi 1 117Vac Fig 2 Complete diagram of more elab orate power pack circuit design 50 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics CNN t EE The time required to recharge the storage capacitor is a determining factor in the rate at which flashes can be repeated Another factor is the need to limit the number of flashes per unit time that the flash tube ex periences because each discharge generates heat in
93. aries and engineering companies One of the best sources of applications information is Pressure Strain and Force an annual publication available to serious inquirers from Omega Engineer ing Inc Box 4047 Stamford CT 06907 Omega also sells a wide variety of metal foil strain gages adhesives and strain gage amplifiers and other instruments ME nn 64 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics BOOKS Electronic Projects Bookson how to build interesting and en tertaining projects occupy a favored niche among electronics enthusiasts This month brings us a bevy of books in this category all of which should pique your interest if you like to build projects We begin with an interesting book by Rudolf F Graf amp William Sheets Video Stereo and Optoelectronics Tab Books Inc soft cover 355 pages 18 95 It of fers 18 projects including printed circuit techniques and materials multi purpose video link transmitter video effects gen erator low frequency active antenna converter wireless headphones and speakers and ultra sensitive picoamme ter electrometer Circuit descriptions and construction information schemat ics parts lists pc guides and component placement diagrams are given Photos of the projects and in some cases of visual effects enhance presentations Next Gordon McComb s Gadgeteer s Goldmine Tab books soft cover 406 pages 18 95 should intere
94. ax imum flexibility the battery oper ated SWR analyzer can be taken to an antenna in the field for measure ments which eliminates any distort ing effects that can be introduced by the coaxial line The SWR Analyzer operates on a 9 volt battery for portable use and on 117 volts ac with an optional MFJ 1312 adapter It comes with an output jack into which a frequency counter can be plugged to provide digital numeric display of the test fre quency The analyzer measures 7 5 x 2 5 x 2 25 89 95 analyzer 12 95 ac adapter CIRCLE NO 3 ON FREE INFORMATION CARD Say You Saw It In Modern Electronics Multimeter Leads A silicone rubber multimeter test lead set with right angle or straight shielded banana plugs and fully insu lated alligator clips is available from Test Probes Inc San Diego CA The Model TL1000 can test a maxi mum of 1 000 volts rms and current to 10 amperes Cable length is 1 2 meters Straight plugs are shielded with spring loaded retractable safety sleeves right angle plugs with fixed rubber sleeves Two leads and two fully insulated alligator clips the latter made of hard plastic for safety and durability are supplied in the TL1000 package Push on hook tips and spade lugs are just two of the accessories that fit the TL1000 Others include adapters for meters with recessed male inputs and extender sleeves that link cables for greater length 14 CIRCLE NO 4 ON FREE INFORMATI
95. back computer even older PC and XT compatibles regardless which version of DOS you use Backpack comes in four configurations 5 25 360K drive Cat BACP360 299 5 25 1 2M drive Cat 12 299 3 5 1 4M 720K drive Cat BACP 14 299 3 5 2 8M drive also read writes 1 4M and 720K Cat BACP28 399 backpack Let Your UU the Work of amp Repetitive Keystrokes How To Talk To Your Computer If you have trouble memorizing all those complicated Control Alt Shift Function commands then Voice Master Key is just for you Now you can simply speak the command bold zoom etc into Voice Master s headset and see it done instantly New Advanced Capabilities The new Voice Master software recognizes up you can plug your printer into the Voice Master System II box System II also includes an external speaker and text to speech to 1 024 words each of which can activate a software different macro Macros can include pre Voice Recognition invokes macros w voice recorded digitized speech or sound files which input New software recognizes over 1 000 words Includes developer kit for sound editing Quick simple installation Includes controller card software and headset Voice Master Key System includes headset amp external Voice Master Order Today Voice Master Key Cat VOIM 149 Voice Master Syste
96. be included if desired For example you might add a voltmeter circuit to monitor charge status as in the more elaborate design In Fig 4 power transformer 77 has a single untapped secondary winding that drives half wave rectifi er DI Because a 6 3 volt winding isn t available for a pilot light neon lamp and its series resistor connect across the ac line after POWER switch 51 and fuse F1 to serve as a POWER indicator Also note that the 150 volts for charging trigger capacitor is taken from bleeder resistor R2 as is done in the Fig 2 circuit However an additional Voltage tap is made in 100 WS PARTS LIST Semiconductors D1 1 000 volt 1 ampere silicon recti fier diode D2 400 volt 1 ampere silicon rectifi er diode SCR1 200 volt l ampere or greater silicon controlled rectifier Capacitors C1 8 zF 500 volt electrolytic C2 600 to 800 4F 500 volt comput er grade electrolytic Resistors 10 tolerance R1 1 000 ohms 10 watt wire wound R2 R7 1 megohm 1 watt carbon R3 470 000 ohms 1 watt carbon R4 15 000 ohms V watt carbon R5 470 ohms carbon this divider between R2 and R3 to supply gate bias to SCRI The SCR trigger circuit is included in this minimal power pack to avoid having 150 volts and high trigger cur rents appear at the camera shutter contacts as would occur if the cam era shutter was directly used to short the trigger capacitor s The half wave rec
97. be should have its own trigger transformer and capacitor to ensure reliable triggering Parallel connected flash tubes should be of the same type if a common stored en ergy source is to divide equally among the tubes Make sure that the energy discharged into any one tube never exceeds the energy watt sec ond rating of that tube The more elaborate power pack contains a storage capacitor for each flash tube in the setup each of which charges to the energy rating of a sin gle tube Thus each storage capaci tor charges to a 100 Ws energy level To ensure that no tube becomes over loaded which could happen if one tube receives the charge of more than one energy capacitor each tube and its energy capacitor is isolated from the others via steering diodes This makes for a bit more elaborate power pack and permits loading each parallel connected tube to its full en ergy rating with attendant greater total ight output It makes little difference whether you use half wave or full wave recti fication except that the full wave supply has a higher ripple frequency that s a bit more efficient in charging the storage capacitor s Availability of a specific transformer can be the guiding factor in your choice be tween half or full wave rectifier cir cuit In any case transformer voltage must be selected according to the 300 WS PARTS LIST Semiconductors D1 thru DS 1 000 volt 1 ampere sili con rectifier diode D
98. bility for unsolicited manuscripts Al low six weeks for delivery of first issue and for change of address Printed in the United States of America Postmaster Please send change of address notice to Modern Electronics 76 North Broadway Hicksville NY 11801 CQ Communications Inc is publisher of CQ The Radio Amateurs Journal Popular Communications Modern Electronics CQ Radio Amateur Spanish CQ and the CQ Amateur Radio Buyer s Guides Say You Saw It In Modern Electronics BEST PRICING ON GENIUS GUARANTEED Includes GM 6000 Mouse Serial Mouse 350 1050 DPI 2 or 3 Button Mouse Mode Dr Genius Software Genius Menu Library User Manuals Genius Mouse Pocket Genius Mouse Pad 9 to 25 Pin Adapter INCLUDES Genius Tablet 12 12 AutoCad Template and Menu File Genius Menu Maker and Menu Library Dr Halo Sofiware Up to 1000 lines per inch resolution Plugs inio standard serial port TABLET with Stylus 279 50 GM6X MOUSE 50 800 DPI w 9 pin Serial amp Dr Halo em GMF303 MOUSE 350 1050 DPI top of the line GS4500 HAND SCANNER 100 400 DPI GS4500 with Prodigy OCR Software GSC105 Color Hand Scanner THE LOGITECH SERIES 9 MOUSE AND MICROSOFT WINDOWS 3 0 Bundled 5 424 149 50 6 00 Shipping SCANMAN
99. ble kit and 118 174 MHz VHF capability with VC 10 option Optional Accessories R 2000 VC 10 VHF converter e DCK 1DC cable kit for 12 volt DC use R 5000 VC 20 VHF converter e VS 1 Voice module e DCK 2 for 12 volt DC operation e YK 88A AM filter e YK 88SN SSB filter 88 CW filter e MB 430 Mounting bracket Other Accessories SP 430 External speaker e SP 41 Compact mobile speaker e SP 50B Mobile speaker e HS 5 Deluxe head phones e HS 6 Lightweight headphones KENWOOD U S A CORPORATION COMMUNICATIONS amp TEST EQUIPMENT GROUP P O BOX 22745 2201 E Dominguez Street Long Beach CA 90801 5745 KENWOOD ELECTRONICS CANADA INC P O BOX 1075 959 Gana Court Mississauga Ontario Canada LAT 4C2 KENWOOD pacesetter in Amateur Radio CIRCLE NO 10 ON FREE INFORMATION CARD many deluxe features such 88
100. bles flash head cables flash heads see text tripods or stands for flash heads ac line cord with plug spacers terminal boards see text dry transfer lettering kit spray paint and clear acrylic spray see text stand s for flash tube s suitable wire see text machine hardware hookup wire solder etc These items are for the flash head assem blies You need one of each per assembly trigger trans March 1991 MODERN ELECTRONICS 49 voltage rating of the storage capaci tor s and flash tube s There are some interesting aspects to the interrelationship between the power supply and flash head The power pack charges the storage capa citors between flashes fairly rapidly so that you can snap another photo again quickly A time constant relat ed to the charge time involves the value of the storage capacitor and series resistance the charge path T From this you can see that larger value capacitors take longer to charge through a given resistance smaller resistance speeds up charging but results in heavier current flow However current flow must be limit ed for safe repetitive delivery without excessive heating Similarly discharge of the storage capacitor through the flash tube which has been ionized by the trigger pulse may see a low resistance path of say 3to 6 ohms or so Discharge can then occur in only a few millisec onds depending on the value of the h capacitor A l
101. c software for fast accurate troubleshooting Refer ence manuals with guidelines and schematics peripheral adapters as parallel printer ports serial communications ports video display memory floppy drives and hard disk drives Only NRI gives you such confidence building real world experience Only NRI gives you both the knowl edge and the professional tools to succeed as today s in demand computer service technician No experience needed NRI builds it in NRI training gives you practical hands on experience that makes you uniquely prepared to take advantage of today s opportunities in computer service You learn at your own convenience in your own home No classroom pressures no night school no need to quit your present job until you re ready to make your move NRI starts you with the basics building on that foundation step by step until you have the knowledge and skills you need for success And all throughout your training you ve got the full support of your personal NRI instructor and the entire NRI technical staff always ready to answer your ques tions and help you achieve your training goals FREE catalog tells more Send today for NRI s big free catalog that describes every aspect of NRI s innovative computer training as well as hands on training in other growing high tech career fields If the coupon is missing write to NRI School of Electronics McGraw Hill Continuing Education Center 4401 Connecticu
102. can operate in conjunction with each other on the PC or Macin tosh but they re also a very useful ad Calendar Creator Plus left and Top Priority right from Power Up Software Corp junct to my manual organizer which is the way I usually use them Both Power Up programs are similar in packaging and documentation They come with both 5 25 and 3 5 inch disk ettes and a booklet style manual of about 50 pages or so Each separate manual is organized along the same lines explain ing what the program does and taking you through set up and use of the pack age The manuals are well written and have lots of illustrations both containing screens you ll encounter and reports that you can generate Calendar Creator Plus CCP as its name implies allows you to print custom calendars that reflect your appointments deadlines and other events of impor tance Version 3 0 which is the version I ve been using doesn t have the fancy clip art libraries that some of the other calendar management programs seen provide but Power Up says that Version 4 0 due out about the same time as this review will have clip art I haven t found the inability to mark Halloween with a little jack o lantern or Thanksgiv ing with a turkey to be much of a detri ment but tastes and needs vary What CCP does allow you to do how ever is generate a very complete variety of calendars in numerous formats De pending upon which p
103. ch works and giving construction details before proceeding to the next Flash Heads Only a minimum of circuitry is included inside a flash head see Fig 1 A three conductor cable terminated in a plug connects each flash head to the power pack through a mating jack This cable should be wired directly to the com ponents in the flash head not through a plug jack arrangement Flash tube leads shouldn t be sub jected to strain They re best secured to solder lugs or support terminals at the points the cable conductors or trigger transformer leads attach Connect the high voltage secondary of the trigger transformer directly to the trigger band on the flash tube Each flash head must be equipped with a separate trigger transformer and trigger capacitor One side of the trigger capacitor connects to the Say You Saw It In Modern Electronics a ee et ee ee I SU CE eee a 5 A ul SE primary of the trigger transformer while the opposite input end of the capacitor is brought back through the cable to the power pack where it s accessible to the firing circuits In essence the trigger capacitor simply connects back to the opposite end of the trigger transformer when the flash is to be fired The primary circuit is completed so that the capa citor discharges through the trans former in only a few microseconds to generate a high voltage firing pulse at the transformer secondary Ap
104. channels simultaneously 100MHz 4kw x tch 2kw x 2ch tkw s ch 6145 4 695 00 Compact Full Feature Models Delayed Swoop Lightweight 13155 2mV Sens 3 Yr Warranty Model 1065 40 5 5 100MHz 4kw ich 2kw 2ch VC 6045 3 049 00 Shown 20MS s SOMHz 2kw x ach 6025 2 295 00 This series provides new functions such as CRT Readout Cursor measurements V 1085 1065 665 20MS s 50MHz 2kw 2ch VC 6024 2 049 00 Frequency Ctr V 1085 Sweeptime Autoranging and 20MS s 20 2 2kw x 2ch VC 6023 1 749 00 Trigger Lock using a 6 inch CRT You don t teel the compactness in terms of performance and operation RSOs from Hitachi feature such functions as roll mode averaging save memory smoothing interpolation pretriggering cursor measurements plotter Interface and RS 232C interface Wah the comfort of ana og and the power of digital V 660 60MHz Dual Trace 1 195 V212 Hitachi Portable Scopes V 665 60MHz Dual Trace w Cursor 1 345 435 DC o50MHz 2 Channel DC offset V 1060 100 Dual Trace 51 425 0 function Allemate magnifierfunctlon 1065 100MHz Dual Trace w Cursor 1 695 Dual V 525 CRT Readout Cursor Maas 1 025 V 1085 100MHz Quad Trace w Cursor 2 045 V 523 Delayed Sweep 995 V 1100A 100 2 Quad Trace w Cursor 2 295 V 422 40MHz Dual Trace 795 V 522 Basic Model 895 V 1150 150MHz Quad Trace w Cursor
105. ck open 55 plug the line cord of the power pack into an ac outlet and set the POWER Switch to You can set 4 so that all three capacitors are connected to the charge line Moni tor the voltage across each of the switched in capacitors in turn and note that one or more may not charge to more than say 200 or so volts af ter a minute or more of charging time This is characteristic of un formed capacitors Turn off ac power to the power pack and allow the capacitors to dis charge through their bleeder resis tors Youcan accelerate discharge by shunting a 500 ohm 10 watt power resistor from the terminal to ground Don t just short the capaci tors to ground with a screwdriver or other very low resistance path Re member to observe all applicable safety precautions when working around the storage capacitors and voltages involved Repeat this charge discharge sev eral times and you ll notice that each time you do the capacitors should charge a bit faster to a slightly greater voltage Depending on the history of the capacitors it should be possible to reach a charge of about 400 volts on each capacitor A capacitor may need more cycles before it charges to this voltage If so continue the pro cess until all capacitors reach this level or more You can now connect the flash heads to the power pack to continue the forming process It s now possi ble to discharge the capacitors by fir ing the flash heads as th
106. consider ably greater than that of foil and wire gages Whilethey produce a much greater resistance change for the same strain than do foil and wire gages silicon strain gages can t be used to measure large strains since the silicon element is very brittle Other electronic sensors can measure strain but for various reasons they aren t used nearly as much as resistive devices They include inductors and capacitors whose electrical parameters are changed by movement of one part of the compo nent with respect to another They also include piezoelectric devices that gener ate a voltage when strained Configurations Two basic kinds of strain gages are shown in Fig 3 The single element gage is de signed to detect strain along a single axis While strain often occurs only along a single axis some structures are subjected to twisting torsion and bending as well as stretching and compression It s possi Say You Saw It In Modern Electronics March 1991 MODERN ELECTRONICS 59 DISCOVER EXPERIMENT LEARN ADVANCE ELECTRONICS LASERS CAD CAM HOME STUDY HEATHKIT HOMEWORKS Now you can learn beginning to advanced electronics at home with the same courses used today in the world s top colleges and tech schools and pay a lot less You ll learn just what you want when you want at your own pace The complete story is in our free catalog Homeworks by Heathkit Order yours today call toll free
107. ct the flash heads to and from the power pack always power down the power pack A flash head may fire on its own when being connected if its capacitor is already charged It s a good practice to energize the system and make a few test firings be fore actually starting to take pic tures This will assure you that the capacitors charge properly and even do minor reforming before a shoot 5 PICKS UP A WHISPER 50 FEET AWAY The model WAT 50 miniature FM tranmitter uses a 4 stage circuit NOT to be confused with a simple wire less microphone Simply snap the unit on top of a 9V battery and you can hear every sound in an entire house up to 1 mile away Use with any FM radio Tunes to any frequency from 70mhz 130mhz Easy to assemble kit includes all parts and instructions Only 29 98 tax incl The WIRELESS TELEPHONE TRANSMITTER model WTT 20 is only about the size of a dime yet transmits both sides of a telephone conversation to any FM radio with crystal clarity Completely automatic Uses power from the telephone line itself never needs a battery Up to mile range Tunes from 70mhz 130mhz Easy to assemble kit includes all parts and instructions On ly 29 98 tax incl Call or send MO VISA MC for Immediate delivery Single kit orders include 1 50 S amp H FREE SHIPPING on orders of 2 or more All orders shipped by U S Mail COD add 4 00 Personal checks allow 21 days DECO INDUSTRIES BOX 607 BEDFORD HILLS NY 1050
108. cular pattern of three strain gages arranged 120 degrees apart Bonding Strain Gages Strain gages are usually cemented to sur faces to be monitored If you don t prop erly bond a strain gage to the surface it may not respond to the strain you want to monitor Both the strain gage and the sur face must be absolutely clean to insure a uniform stable bond It may be neces sary to first buff the surface with emery paper and to then scrub with a cleaning solvent for best results Various kinds of cement can be used to bond strain gages Duco cement can be used with paper base gages Cyanoacry late adhesives are often used with foil gages resin substrates Whichever you use it s important that the cement be completely dry or cured before readings from the strain gage can be considered re liable Even though the cement around the edges of the gage might be cured the cement under the central portion of the gage might still be wet For detailed infor mation about bonding commercial strain gages see the literature supplied by the various manufacturers Temperature Problems Foil and wire strain gage performance is affected by temperature in at least two ways Since the resistance of the metal foil or wire that forms the element of the gage varies with temperature changes in temperature can cause erroneous signals Another temperature effect can result when the coefficient of expansion of the strain gage differ
109. cussion on theory applications and experiments of interesting ana log digital and computer circuits System Overview The Digital Signal Generator serves as the stimulus that allows you to ex Say You Saw It In Modern Electronics amine experiments that involve digi tal circuits You wire the circuits to be explored on a solderless bread board or a Wire Wrap prototyping board depending on personal pref erence and complexity and use the Oscilloscope or Logic Analyzer to observe both inputs and outputs The advantage of using a Logic Analyzer when working on digital circuits is that you can observe both inputs and outputs simultaneously If you were to study the operation of a 74LS165 shift register for exam ple you would find that you need eight data signals a signal to load the data into the register and a clock to shift the data out ofthe registers The Digital Signal Generator described here produces the needed signals while the Oscilloscope lets you ob serve inputs and outputs Computer circuits like analog to digital A D and digital to analog D A converters input and output ports memory ROMs interrupt systems displays and digital signal processors DSPs can be studied us ing the 8088 test platform included in this project For example A D and D A converters wired on the Wire Wrap prototyping board can be con nected to the I O ports An analog signal supplied by the Function Gen erator conn
110. d as a programmable attenua tor by feeding the signal into its volt age reference pin Digital control logic switches the attenuation of the signal at a high rate creating the car rier to produce modulation This implementation is limited by the bandwidth of the D A converter and requires extensive support logic Balanced Modulator Chip The versatile low cost and readily available LM1496 balanced modula tor IC can be used for DSB C SSB and DSB modulation Choice of modulation depends on how you bias this chip In operation the LM1496 circuit modulates two signals by chopping the modulated signal at the rate of the carrier frequency in effect using the chopping operation as a multiplier see Fig 5 Internally the LM1496 uses two sets of transistors configured as dif ferential pairs and only a small volt agetoswitchatthecarrier frequency The differential pairs are fed by con stant current sources biased by exter nal resistors and the modulating sig 1 MH2 OSCILLATOR AMPLIFIER SELECT INPUT SIGNAL CARRIER SIGNAL CHOPPED SIGNAL Fig 5 How signal chopping results in amplitude modulation nal Therefore the dc offsets applied to the input determine the type of transmitter configured Close examination of Fig 5 reveals that chopping is indeed multiply ing For example look at the input signal at the top of the illustration at any time along the
111. d you don t need a license for this one We begin here with a discussion of AM radio transmission in all its guises Then we present full details for building a low power license free AM transmitter that broadcasts a signal that can be received with any AM broadcast band radio Because the transmitter radiates less than 1 milliwatt of power from its short an tenna no FCC license is required to build and operate it You can voice modulate the transmitter through a microphone or from a higher level source like a tape deck or compact disc player simply by flipping a switch AM Transmission Amplitude modulation or AM is a means by which two signals are com bined so that one modulates the other The signal to be modulated called a carrier is usually constant and much greater frequency than the modulat ing signal The modulating signal can also be fixed in frequency though it s usually variable and in the audio range so that voice music and other m u A Li TRA NSMITTER sounds can be heard after demodula tion at the receiving location Though an audio frequency signal can be transmitted directly econom ics among other reasons dictate that it be impressed on a carrier This is because transmission and reception of asignal depend on antenna length The lower the frequency to be trans mitted the longer the antenna need ed at both ends If an audio signal of say 5 kHz were to be transmitt
112. e Carriage 132 Column NEW High le 200 CPS Draft 110CPS Correspondence 35 CPS NLQ UNBELIEVABLE VALUE Prints Black 4 Colors and 8 Colors BiDirectional Dot Matrix BRAND NEW 9 Wire Parallel Interface Tractor Included AMSTRAD COLOR VGA FRONT BOTTOM REAR PAPER FEED List 1 995 ULTRA Res 12 VGA PC Model 12HR Paper Rack Available Tilt amp Swivel 720x480 Anti Glare Screen i 512 Change liebe es 39 9 2 8 1 YEAR WARRANTY Quantity Pricing CALL 90 Day BRAND MEW 1 Warranty STB VGA Extra Card Nw CITIZEN MSP 50 300 CPS 50 NLQ Narrow Carriage 9 Wire Epson IBM AMDEK 600 LOR Compatible Push or Pull Tractor Zero Tear Off Top or Bottom Feed Automatic Paper Loading 8K Buffer Parallel Interface 14 RGB Color 600x200 List 550 18 Month Manufacturers Warranty Green Amber Switch Tilt amp Swivel 1 9 9 rap Sens Ribbons Avalable 269 BRAND NEW ONLY Color Kit 7 Colors 59 SPERRY RGB COLOR Serial Interface 49 Font Card Sans Serif Orator 59 3 249 6 245 12 239 24 229 PRINTER POWER LIMITED QUANTITIES 14 Cotor Monitor w Color Card DIABLO DBOIF 499 80 CPS Ltr Qity w Sheet Feeder Returbished 40 200 1695 New 389 330 CPS 66 NLQ Wide Carriage CENTRONICS 1368 New 299 180 CPS 34 NLQ Wide Heavy Duty BR
113. e discharge load Close 55 and continue to charge and fire the heads until the ca pacitors can be charged to at least 450 volts in a reasonable amount of time 20 to 30 seconds The capacitors have now been formed and should accept full charge It s a good idea to cycle capacitors of the electrolytic type even if un used by charging and firing a few times every month or so This keeps the capacitors fully formed and obvi ates having to go through the re forming process again To form ca pacitors from scratch or after un known periods of time on the shelf may take hours to accomplish if in terna heating is to be minimized This is the reason for using at least 5 000 ohms of charging resistance in the initial forming steps The operat ing circuit uses only 1 000 ohm values for charging resistors R7 R2 and R3 These resistors limit the charging currents applied to fully formed capacitors They also limit the maximum current drawn from the power supply and keep the flash tubes from suffering hangover from current coming directly from the power supply instead of from only the storage capacitor After you secure the side panels to the enclosure there s little chance for electric shock from the power supply or flash system Of course complete ly enclose the flash heads since high voltages appear at the tube terminals The interconnecting sockets for at tachment of the heads to the power pack are polarized t
114. e re ports The most frequently used report at least for me is the Daily To Do list which is the printed version of the To Do Today screen mentioned above It lists the tasks Priority tasks first that are either past deadline without having been completed or that have the current or no date entered as the due date The Daily To Do list also has a list of completed tasks that haven t been wiped from the system as well as room for penciled in ad ditions as the day progresses Other reports include files listings cat egory listings a completion report by due date a weekly check off report which shows an entire week s events and goal cards that list all subtasks as signed to a particular goal As with Cal endar Creator Plus you can print these reports in a wide variety of sizes includ ing several organizer sizes to fit popular systems such as DayTimers and FiloFax and even my 12 knock off Calendar Creator Plus and Top Priori ty aren t miracle solutions How effective they are depends on how they re used and how often I m still not all that orga nized and the piles are still being built and toppled But I m a lot more orga nized with these two programs than I was before I started using them At 59 95 for Calendar Creator Plus and 99 95 for Top Priority I think they re well worth the money ME Products Mentioned Calendar Creator Plus amp Top Priority Power Up Software Corp 2929 Cam
115. ects to the ANALOG input The processor program can invert filter and limit the range or simply turn the data around and out to the D A circuit You monitor circuit re sponses and actions using the analog and logic analyzer features included in the Digital Storage Scope Analog circuits like operational and power amplifiers comparators filters sensors and power control circuits can be wired on the prototyp ing station and evaluated using the Function Generator and the Digital Storage Scope You can use the pro totyping station to build hundreds of useful circuits that illustrate basic ac and dc circuit principles magnetic and transformer principles power supply operation and to demon Say You Saw It In Modern Electronics DIGITAL STORAGE SCOPE AND LOGIC ALYZER LOGIC AND ANALOG PROBES PROTOTYPING STATION DIGITAL SIGNAL AND FUNCTION ENERATOR CT DAROHO DO DZD ED DIGITAL STORAGE SCOPE LOGIC ANALYZER LOGIC AND IANALOG PROBES PROTOTYPING STATION CIRCUITS LAB DIGITAL SIGNAL AND FUNCTION GENERATOR 40 PIN CABLE Or DZORW nOr DZD 23 DIGIT SIGNALS DIGITAL STORAGE SCOPE AND LOGIC ANALYZER NALOG PROSES PROTOT YPING STATION DIGITAL SIGNAL AND FUNCTION GENERATOR OF CIRCUITS Lae Fig 1 Overview of how various Experimenter Labs ca
116. ed di rectly the antenna would be an im practical length Its length is calcu lated using the wavelength formula A cf where is wavelength in meters c is the speed of light considered to bea constant 300 000 000 meters per sec ond and fis frequency in Hertz Hz Since we already know two of the un knowns for this formula the speed 38 MODERN ELECTRONICS March 1991 at Oe ANTENNA ME SIG NAL E 9 va a 9 SIGNAL IN of light and frequency antenna wavelength is calculated as follows c f 300 000 000 5 000 60 000 meters A A As you can see 60 000 meters 60 km is an exceedingly long antenna length The cost of building such an antenna would be prohibitive as would be installing it Using a high carrier frequency such as 1 5 MHz to convey the 50 kHz signal considerably shortens the effective length of the antenna needed to transmit it This reduces both cost and real estate on which to mount the antenna When a carrier signal of a considerably greater frequency than that of the modulating signal is used only the frequency of the carrier need be considered in the wavelength for mula used to calculate antenna length Say You Saw It In Modern Electronics Fig 1 Frequency distribution details for A speech range profile B modulated spectrum showing both negative and Dositive frequency components C SSB spectrum and D DSB C s
117. equency box elsewhere in this article signals gen erated when a number is punched in ADDRESS DATA 0 ADDRESS DATA 1 ADDRESS DATA 2 ADDRESS DATA 3 ADDRESS DATA 4 ADDRESS DATA 5 ADDRESS DATA 6 ADDRESS DATA 7 45V ADDRESS LATCH ENABLE PROGRAM STORE ENABLE ADDRESS 15 ADDRESS 14 ADDRESS 13 ADDRESS 12 ADDRESS 11 ADDRESS 10 ADDRESS 9 ADDRESS 8 Fig 1 Pinouts for the 8031 microcontroller used in this project 18 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics A Shocking Offer Now for the first time in CIE s 56 year history you do not have to be enrolled at CIE to receive our introduc tory Electronic and Electricity Lesson Modules Available for a limited time to non students for the shockingly low price of only 99 50 With CIE s patented AUTO PROGRAMMED method of learning you ll quickly learn and then master the basics of electronics and electricity and then move on to DC AC circuit theories fundamentals of bi polar junction transistors BJT field effect transistors FET wiring diagram and sche matic readings component identification soldering techniques and much much more Your commitment to CIE ends with your payment but CIE s commitment to your Success just begins when you receive your 39 lessons exams binders and equipment This special introductory price includes all the benefits and assistance CIE normally extends to its students and graduates
118. er Joe Desposito Forrest Mims III Ted Needleman Contributing Editors BUSINESS STAFF Richard A Ross Publisher Art Salsberg Associate Publisher Dorothy Kehrwieder General Manager Frank V Fuzia Controller Catherine Ross Circulation Director Melissa Kehrwieder Data Processing Carol Minervini Data Processing Karen Nauth Customer Service ADVERTISING SALES ELECTRONIC ADVERTISING Jonathan Kummer 516 681 2922 FAX 516 681 2926 COMPUTER ADVERTISING Ken L Wood 407 264 0545 FAX 407 264 0473 Offices 76 North Broadway Hicksville NY 11801 Tele phone 516 681 2922 FAX 516 681 2926 Modern Electronics ISSN 0748 9889 is published monthly by CQ Communications Inc Subscription prices payable in US Dollars only Domestic one year 18 97 two years 36 00 three years 53 00 Canada Mexico one year 21 00 two years 40 00 three years 59 00 For eign one year 23 00 two years 44 00 three years 65 00 Foreign Air Mail one year 76 00 two years 150 00 three years 224 00 U S Government Agencies Subscriptions to Modern Electronics are available to agencies of the United States government including military services only on a cash with order basis Requests for quotations bids con tracts etc will be refused and will not be returned or processed Entire contents copyright 1991 by CQ Communications Inc Modern Electronics or CQ Communications Inc as sumes no responsi
119. er control over what you re doing in the end They pro vide various design checks do some automatic juggling around of foil traces and connections to provide you with the best layout and even set up things for automated pcb produc tion and parts assembly We examined a bevy of such pro grams ranging in price from roughly 200 to 2 500 which we planned to present in this issue However we re holding off until next month in order to do as much justiceto the reviews as possible Working with one of the programs myself I can tell you first hand that it s easier said than done first time out The same goes for schematic capture programs One isn t born to it It requires some strong efforts to work it all out and I d guess some fair amount of time to make it an effici ent alternate to hand laid foil pat terns few of our writers have been doing this for professional reasons over the years however and I ve ob served them moving along the CAD path at a brisk pace So I know it can indeed be done better this way But you ve got to make the investment in dollars and put in learning and prac tice time to make it pay off The PC CAD world of rats nests vias autorouters color layers li braries nodes force vectors post processing mirroring solder masks and the like can be very rewarding in both a personal sense and for car eer reasons On the latter there are plenty of well paying job openings for people who
120. ession or expan sion Airplane wings are subjected to flexing Shafts and axles are subjected to torsion Many structures can experience more than one kind of strain and the di rection of maximum strain can vary over a period of time Strain gages permit the strain experi enced by these structures to be continual ly monitored over their lifetime Strain gages can also provide a warning when excessive strain occurs The ability of a strain gage to detect strain makes possible many kinds of sen sors For example a strain gage can be at EXPANSION CTENSION COMPRESSION tached to a pedestal that supports a weight to form an accelerometer When the object to which the accelerometer is mounted moves the weight tends to re main at rest This causes the pedestal to bend thereby distorting the strain gage A Strain gage can be bonded to a flexi ble diaphragm and used to detect pres sure changes in sealed vessels When bonded toashaft a strain gage can detect torque when the shaft is rotated A dis placement sensor can be made by mount ing a strain gage on a flexible arm that s moved by flowing gas or liquid or a me chanical force Commercial Strain Gages Most commercial strain gages have a sen sing element made from a thin metal wire or a foil pattern with an electrical re sistance that changes when the element is compressed expanded or bent Some strain gages have a silicon sensing ele ment Figure 2sh
121. etal a new alloy specially de signed for this contact arrangement was developed in conjunction with AMP Inc s Advanced Development Labora tory and is much harder than gold Each pin is six thousandths of an inch of solid usable metal Each time Cyber Card is inserted any oxidation or debris build up on the pins is wiped clean be cause of the connector s 250 gram nor mal force which further increases the card s dependability The reliability of a card also depends on the number of contacts each of which isa potential failure point CyberCard re duces the number of contacts from the typical 68 to just five which greatly im proves reliability This reduction is made with a special chip the DS1280 3 Wire to Bytewide Converter that supports up to 4 megabits of memory using only three input signals clock data and reset in addition to power and ground JEDEC standard bytewide SRAM in side the card is adapted to a three wire 1 megabit per second serial interface with the D51280 With Cyclic Redundancy Check CRC circuitry the chip also monitors serial data transmission through the connector detecting any connection problems This ensures integrity of the card s data transfers Since memory cards can be subjected to harsh environments and handling by the user CyberCard has special provi sions to keep internal chips safe Cyber Card s ground contact pin is extended to ensure that it makes first and breaks las
122. figuration limits dc gain to about 1 This elimin ates the possibility of saturation of either amplifier at dc The JFET op amps provide immunity to noise at high input impedance The U4 oscillator section is the familiar Colpitts configuration It s simply a differential pair with an LC tank and feedback to provide re generation The modulating fre quency can be changed here with ease The values of capacitor and inductor L in parallel determine car rier frequency using the formula 1 2 1 With values of 50 uH and 450 pF for LJ and respectively fac tors out to 1 060 kHz or 1 06 MHz This frequency is in the middle of the AM broadcast band If you use a dif ferent transmit frequency recalcu late the values of and L using the above formula LM3046 U4 is simply four npn transistors on the same piece of sili con inside the chip The oscillator could be built using discrete compo nents but the LM3046 approach is better because its matched transistors are on the same substrate and with stand the same processing parame ters The transistors also heat and cool together for more stability LM1496 U3 is configured for DSB C transmission by offsetting the dc component applied to the in put using R O and R11 The poten tial at the junction of these two resis tors is 9 6 volts The values of R8 amp and R9 are the same as those of R71 and R O but their arrangement pro vides a potenti
123. for evaluation purposes Other features include automatic horizontal and vertical ranging se lectable averaging from 2 to 256 bits smoothing pre trigger view dual timebase with calibrated delayed sweep alternate sweep roll mode and trigger and universal 90 to 125 volt ac power supply CIRCLE NO ON FREE INFORMATION CARD Telephone Line Autoswitch SmartMax II from MaxTrek Inc Hayward CA allows two or more devices to share a single telephone line and automatically switches any of them as needed by an incoming call Two versions are available The Model 6000 provides automatic switching between a telephone in strument and fax machine while the Model 6500 adds automatic switching for a third device that can be a com puter modem credit card terminal or other accessory Both models offer such common features as simple plug in installa tion for single line phones power to handle multiple extension telephone instruments compatibility with US phone systems TADs and fax ma chines a sentry mode for nighttime operations programmable ring count for more switching options a hold feature extended transfer and selec tion menu Touch Tone and rotary dial transferring capability and choice of operating modes to fit a wide variety of applications Power for SmartMax II comes from an ac outlet The device con sumes 7 3 watts on idle and 17 watts during the ring cycle Its ring output is 90 volts
124. hat are generated by the telephone instrument These tones are further divided into groups of four low tones and four high tones A tone is the algebraic sum of one low tone and one high tone frequency An example of the basic tones and the combined tone is shown in Fig A The top waveform is the row 3 825 Hz tone the center waveform the column 2 1 336 Hz signal and the bottom waveform the combined row 3 and column 2 waveform as it is transmitted over the telephone line Rows and columns refer to the conven tional Touch Tone keypad layout Rows are numbered horizontally in consecutive order from top to bottom while columns are numbered consecu tively from left to right as illustrated in Fig B Note that for special communi cation functions tone dials can include additional keys labeled with the letters A through D and the symbols and Each keypad key occupies a unique ANNA M V Fig A DTMF tone pairs generated when button 8 on a Touch Tone keypad is pressed include a row 3 852 Hz low group top column 2 1 336 Hz high group center and algebraically com bined bottom tones position ina4 x 4 matrix With this ar rangement the 5 button is located at the juncture of row 2 and column in the matrix the 7 button at the juncture of row 3 column 1 and so on Pressing any given button on the Touch Tone keypad results in genera tion of the algebraic sum of theto
125. he AL 4000 can accommodate the high est performance disk drives The AL 4000 carries a lifetime warran ty Initial small quantity and evaluation boards are being sold for 895 each which includes 2MB of cache memory Rugged SRAM Card Dallas Semiconductor 4401 S Beltwood Pkwy Dallas TX 75244 has developed a nonvolatile four million bit SRAM credit card size package that is rugged ized for industrial environments Devel oped in conjunction with AMP Inc the DS6417 CyberCard EV 4 megabit mem ory withstands 50 000 insertions and withdrawals This superior durability is a result of new chip development and a new metal alloy used for the contact pins According to the company existing memory cards require gold plated con p M ON 68 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics tact pins for extended use But because gold is soft and the coating is typically 30 micro inches thick the plating wears away quickly exposing the base metal be neath When the base metal such as nickel plating over copper is exposed for any length of time oxidation occurs and the connection is no longer reliable Solid gold contacts would work but they would be too expensive and too soft CyberCard has no plating Instead it uses a new solid metal that is 2 000 times thicker than gold plating and withstands insertions until the metal disintegrates That m
126. he burst sequence of the i486 processor With burst memory protocols proces Sors can quickly transfer a succession burst of consecutive memory words per bus cycle rather than a single memory word per cycle Since these burstRAMs are designed to support 50 MHz clock rates they can keep up with even en hanced versions of the 68040 and i486 yet to come The MCM62960 synchronous RAM provides cache memory for memory ad dress protocols specific to Sparc micro processor applications The MCM62940 MCM62486 BurstRAMs and the MCM62960 syn chronous static RAM are packaged in a 44 pin plastic leaded chip carrier PLCC E A Say You Saw It In Modern Electronics I E Telephone Call Restrictor page 25 From To 1 1 pin 1 IC6 15 2 RY2 R 3 15 1 9 C3 16 IC3 27 17 IC3 22 18 XTALI T 19 C2 T XTAL1 B 20 IC1 31 C1 B C2 B R42 L GND 21 1 305 22 1C304 23 1 301 24 1C3Q3 25 1 3 2 26 1 4 1 27 IC4Q 28 IC4 3 29 1C5 2 30 1 2 11 32 IC2 18 IC3 19 33 IC2 17 IC3 18 34 IC2 14 IC3 17 35 IC2 13 IC3 16 36 1 2 8 1 3 15 1 6 14 37 1 2 7 1 3 13 1 6 13 38 1 2 4 1 3 12 1 6 12 39 IC2 3 IC3 11 IC6 11 40 C3 5V IC2pin 1 IC2 10 C4 B GND 2 IC3 10 5 IC3 9 6 1 3 8 9 1030 12 ICX 6 15 1 3 5 16 1 3 4 19 1 3 3 20 4 5V this time Include o
127. he tape deck or CD player from the radio Having verified that the high level input works power down the trans mitter and unplug the tape deck or CD player from it Plug your micro phone into the MICROPHONE jack and set the SELECT switch to MIC Power up the transmitter and speak into the microphone If you fail to hear your voice coming from the AM radio or the signal sounds distorted adjust the GAIN control until the sig nal sounds clean Experimenting This Transmitter project serves well as a basis for studying DSB C ampli tude modulation The LM1496 bal anced modulator can easily be con figured for DSB and SSB modula tion though additional filtering is needed to complete the design How ever the buffer oscillator and in put stages remain as they are shown Implementation of SSB and DSB also requires a suitable receiver to pick up and demodulate the trans mitted signal DSB C modulation simplifies things because just about everyone already has a standard AM broad cast band radio to receive its trans missions If you have a shortwave re ceiver that can tune SSB transmis sions you can experiment with the SSB and DSB transmission Say You Saw It In Modern Electronics Project Triple Head Photo Flash System Gives the amateur photographer the advantages of multiple source studio lighting systems for shooting professional quality portraits By Maurice P Johnson egardless of
128. her events of impor tance Version 3 0 which is the version I ve been using doesn t have the fancy clip art libraries that some of the other 66 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics calendar management programs seen provide but Power Up says that Version 4 0 due out about the same time as this review will have clip art I haven t found the inability to mark Halloween with a little jack o lantern or Thanksgiv ing with a turkey to be much of a detri ment but tastes and needs vary What CCP does allow you to do how ever is generate a very complete variety of calendars in numerous formats De pending upon which printer you re using Calendar Creator Plus can generate cal endars of up to 11 by 17 inches Most of your calendars however will be printed on letter or legal size paper or the special paper Power Up offers for several sizes of organizers The sharpest and most at tractive calendars are generated on a laser or Hewlett Packard DeskJet printer but the software does support almost any dot matrix printer that can emulate Ep son or IBM graphics Data entry which can be the most time consuming part of using a program such as this is facilitated by features such as wildcards using the asterisk in repeat ing fields and the Overlay Util
129. hift load input Note re verse slash symbol indicates that the load input is active low The 74LS165 also features a clock inhibit and a com plemented inverted serial output Clocking or shifting data that has been entered into the registers is accom plished via a low to high transition of the clock input while SH LD is high Parallel loading is inhibited when the SH LD pin is held high The logic level at the serial input is present at the output after the first eight shifts pro vided no additional parallel data has been loaded Applications The 74LS165 is used to convert an eight bit parallel data format into a serial for mat which is desirable when sending data over a two conductor link or when shifting parallel data into serial inputs This device was used in the Digital Stor age Oscilloscope to transfer the data from the eight bit parallel display mem ory to the serial display registers inside the LCD These registers require the data be in serial format The 8251A USART used in this proj ect has this type of register embedded in a relatively complex device to transmit eight bit parallel data to the serial RS 232 output pins Other shift regis ters convert serial data to the parallel format which is required at the receiv ing end of serial data if data is to be en tered into an eight bit parallel port Lab Experiments The object of this experiment is to gen erate eight bit parallel data a shift cl
130. highly ex perienced in distance education teaching by correspondence through printed materials computer materials fax and phone No commuting to class Study at your own pace while continuing on your present job Learn from easy to understand but complete and thorough lesson materials with additional help from our instructors Our Computer B S Degree Pro gram includes courses in the BASIC PASCAL and C languages as well Assembly Language MS DOS CADD and more Our Electronics B S Degree Pro gram includes courses in Solid State Circuit Analysis and Design Control Systems Robotics Analog Digital Com munications and more An important part of being pre pared to move up is holding the right college degree and the absolutely neces sary part is knowing your field Grantham can help you both ways to learn more and to earn your degree in the process Write or phone for our free catalog Toll free 1 800 955 2527 or see mailing address below e Accredited by the Accrediting Commission of the National Home Study Council GRANTHAM College of Engineering Grantham College Road Slidell LA 70460 SOLID STATE DEVICES Fig 2 Dallas Semiconductor s Cyber products includes the DS6400EV Extra Volume version of CyberCard pack to cram in more electronics CyberCard comes with up to 4 mega bits of memory Because of a built in lithium energy source and low leakage CMOS circuitry the
131. ia ture cable The microphone itself measures 0 98 inch long and weighs just 0 25 ounce It can be powered by any source capable of delivering 9 to 52 volts dc CIRCLE NO 11 ON FREE INFORMATION CARD Variable DC Power Supply B amp K Precision s Model 1611 bench type power supply offers a contin uously variable 0 to 50 volt dc out Say You Saw It In Modern Electronics put at 2 amperes with 0 01 regula tion and less than 1 mV rms ripple The supply is rated for continuous operation at maximum output power without overheating It features two analog meter movements for simul taneous monitoring of voltage and current output Two current ranges are selectable and have coarse and fine adjustment controls to assure precise settings Built in are reverse polarity pro tection from an external dc source overload protection thermal protec tion short circuit protection and current limiting The and out puts are fully isolated to permit either polarity to be floated or grounded ac cording to the application Two Model 1611 power supplies can be parallel connected to double avail able output current or series con nected to double available output voltage Automatic mode selection chooses between constant current and con stant voltage with a LED lighting to inform the user which has been se lected In constant voltage applica tions a current limit can be preset such that if variations in the load cause the
132. ight specially adapt able pins identified as PORT at pins 1 through 8 of JCJ Using this port through program control informa tion can be read from and written to these pins Operation is like the case with the data bus but with an excep tion no enabling pulses are needed to turn on any specific chips By telling 1 to output a decimal number between 0 and 255 you can place any combination of 05 and 1s on the port pins Also under pro gram control the 8031 can be di rected to read the binary code applied to these pins Note that STROBE pin 10 of JC6 is connected to PORT pin 1 PORTI 1 In the Call Restrictor the program in C5 tells C1 that a valid tone has been detected by only when pin 1 of ZC is at logic 1 In con trast if pin 1 of C1 is at logic 0 the 8031 refuses to acknowledge as us able information the binary data on the data bus Another section of the project that uses PORTI is the base circuit of QJ On initial start up pin 3 of C3 is at logic 1 This voltage is applied to the base of Q1 through R15 At this time RY1 is energized and its contacts are closed These now closed contacts can be used as a telephone hook switch By wiring the contacts in se ries with the red insulated telephone line conductor as shown in Fig 3 D any telephone instrument con nected to the line is under control of IC1 not the caller If JC senses that 1900 976 or Oare the first digits dialed when a calli
133. in 7 above 9 Vas Negative power supply voltage normally grounded 10 TOE through D3 internal pull up provided on chip 11 DO TOE provide code corresponding to last tone 12 DI See pin 11 above 13 D2 See pin 11 above 14 D3 See pin 11 above 15 StD when voltage on St GT falls to less than Vig 16 ESt signal causes ESt to return to logic 0 17 St GT stant its state a function of ESt and voltage on St 18 Vaa Positive power connection Pin Functions for the G8870 DTMF Receiver Decoder Chip Gain Select provides access to output of front end differential Reference Voltage nominally V44 2 can be used to bias inputs Clock Input 3 58 MHz crystal connects between pins 7 and 8 Three state Output Enable Input logic high enables outputs DO Three state Data Outputs with pins 12 13 14 when enabled by Delayed Steering Output presents logic 1 when received tone pair has been registered and output latch is updated returns to logic 0 Early Steering Output presents logic 1 immediately when digit algorithm detects recognizable tone pair any momentary loss of Bidirectional Steering Input Output Time Output voltage great er than V detected at St causes device to register detected tone pair and update output latch voltage less than Vs frees device to accept new tone pair GT output resets external steering time con Fig 2 Details for G8870 DTMF receiver chip used in this project A Block dia gram of internal circ
134. ined will the bridge become unbalanced Noise Problems Strain gages exhibit such tiny changes in resistance that it s usually important to guard against electrical noise that might interfere with the measurement of the re sistance change Noise can enter the strain gage directly if its exposed wire leads touch the metal structure to which the gage is bonded Noise can also be in duced into the strain gage s wire leads particularly if they re long These prob lems can be prevented by using shielded cable and by carefully insulating any ex posed wire leads and connections Amplifiers You can use a digital multimeter to mea sure the very small changes in a strain gage s resistance In most applications however an amplifier is used to beef up the very tiny voltage or current changes caused by strain Figure6shows how to connect an oper ational amplifier to a strain gage that forms part of a Wheatstone bridge The bridge circuit permits the output to be set to any desired level simply by adjusting R4 Theresistance of R4 should be some what greater than the maximum expected resistance of the strain gage Automatic temperature compensation can be provided by using identical strain gages for 1 and R3 Increasing R5 in creases the circuit s gain and hence its sensitivity to strain The output voltage of the circuit in Fig 6 decreases as the resistance of R3 in creases In other words an increase in strain cause
135. io stations in Japan due to an equal facilities policy between cities As a result Tokyo s 12 million people share only four FM stations two commercial one public and one that carries only school lectures The digitally transmitted music will be able to be copied on digital tape recorders OPTICAL DISK DATA STORAGE JUKEBOX A 5 1 4 optical disk drive jukebox the LF500 Autochanger from North American Philips LMS Company in Colorado Springs was recently announced It s a data backup and archival storage device rather than a simulated Wurlitzer however But the Autochanger does hold up to 32 removable 653MB ISO standard optical disk cartridges and is able to mix WORM and rewritable media It s said to be compact enough to fit alongside a workstation or desk AN ELECTRONIC NOTARY A digital time stamping service prototype developed at Bellcore is said to be able to affix a tamper proof time stamp seal to any electronic document The challenge was that unlike with paper and ink there hasn t been a way to tell if part of an electronic document had been tampered with if it was carefully overwritten or fully wiped out The basis of the cheat proof system is the creation of hidden unalterable identifiers such as a hash value combined with electronic time stamping In essence it imposes a digital fingerprint INTEGRATED DSO TELESERVICING Tektronix introduced the first commercial teleservicing software that incorporates three function
136. ious experience needed No costly school No commuting to class The Original Home Study course prepares you for the FCC Commercial Radio telephone License This valuablelicenseis your professional ticket to thousands of exciting jobs in Communications Radio TV Microwave Maritime Radar Avionics and more even start your own business You don t need a college degree to qualify but you do need FCC License No Need to Quit Your Job or Go To School This proven course is easy fast and low cost GUARANTEED PASS You get your FCC License or money refunded Send for FREE facts now MAIL COUPON TODAY COMMAND PRODUCTIONS FCC LICENSE TRAINING Dept 206 P O Box 2824 San Francisco CA 94126 Please rush FREE details immediately NAME ADDRESS CITY STATE 21 2 2 2 2 2 222 2 2 2 J e dl March 1991 MODERN ELECTRONICS 61 ELECTRONICS NOTEBOOK Fig 4 Full bridge rosette strain gage configuration blems is to connect two identical gages in a Wheatstone bridge as shown in Fig 5 One gage the sensor R3 is bonded to the surface to be monitored The second gage the reference or compensation gage RI is installed on a nearby surface that s identicalto the first but not subject to strain As long as both gages are in stalled in the same way both will remain at the same temperature The bridge re mains balanced and no current flows Only when the sensor gage is stra
137. is expensive and requires many components to implement AM Radio Detection Graphic examination of DSB C transmission and reception demon strates the economy of this format Referring to Fig 2 carrier signal A Modulation 1 106 Output Modulation Output intact as in Fig 1 B Although the transmitted signal contains redun Fig 4 Ways of achieving amplitude modulation by the A logarithmic method and B the analog to digital method ei a a a am c r c n 00 40 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics is multiplied by dc offset modulating signal B to yield transmitted com posite modulated signal C Signal C is received and input to the detec tor arrangement shown in Fig 3 The simple diode resistor capacitor cir cuit shown is all that s needed to re trieve the transmitted signal Of course a receiver would also contain a preceding r f amplifier and an amp lifier to drive a speaker The demodulated signal exiting the detector is usually ragged as shown in Fig 2 D After final filtering rag gedness is removed producing a clean signal like that in Fig 2 E Recall that the double sidebands contain the same information Hence efficiency can be measured as the ra tio of the power of one sideband to total transmitted power From this it s easy to see that SSB is most effici ent and DSB C is least efficient The DSB C transmitte
138. ities that let you delete rename copy and merge overlays Once you ve finished with your over lay just select PRINT from the main menu The software will let you choose a size and style and then print your custom cal endar If you run into any problems the manual has a short but to the point troubleshooting section and context sen sitive on line help is available by pressing the Fi key Top Priority installs in a similar man ner and is just as easy to use However in stead of calendar oriented events it lets you maintain complex and complete to do lists Although I use only a single list with everything I can think of on it you can create different lists for different pur poses Top Priority lets you enter a task with a set due date or deadline or an event like an appointment that has both a date and time When used together with Cal endar Creator Plus you can enter data in either of the packages and export and im port deadlines and appointments back and forth When used in this manner the two pieces of software operate somewhat synergistically Top Priority also offers a host of fea tures that I don t use much but can con siderably extend its power You can pri L P r i1 i p caa r E Say You Saw It In Modern Electronics oritize tasks using the letters A through Z with A having the highest priority This places priority tasks at the top of your lists and also reminds you
139. know their way around CAD for generating both schematics and pcbs not to mention other computerized drawing modes for engineering and manufacturing purposes Now that we have a batch of 386 Personal Computers we re giving se rious consideration to doing more of our drafting and printed circuit board work with them Their auto matic forward and back annotation will do more to ensure that foil pat terns schematics and parts lists accu rately reflect each other and do it fast Additionally a change in one area is automatically reflected in the others More and more electronics and computers are being wedded to each other Welcome to the world of high tech hd an 6 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics LETTERS NENNEN For Greater Safety The Supply for IC Experi menting schematic diagram that ap peared in the January issue of Modern Electronics would benefit enormously in terms of both user and experimenter cir cuit safety with addition of another 1 5 capacitor in the other leg of the ac linein put As the circuit stands diodes can fail and the possibility of a shock hazard ex ists because there is no realisolation from the ac line John Hoffman Manhasset NY Religious Convictions Not An Issue As subscribers to Modern Electronics my son and I admire the fact that you do not consider faith or religious conviction of your writers when eval
140. laborate design is shown sche matically in Fig 2 This version has a center tapped transformer and two diodes for full wave rectification Say You Saw It In Modern Electronics In addition to the impedance of power transformer 77 series resis tors limit the charging current Inde pendent storage capacitors are used one per flash head to permit each flash tube to be fired at maximum en ergy Yet any tube will never be over stressed since steering diodes D3 D4 and D5 isolate the capacitors from each other If one flash tube fails to fire its associated capacitor doesn t discharge The other capaci tors won t be effected nor will the unfired capacitor dump into those that do discharge This keeps any flash head from ever being over stressed while full energy is supplied to each tube For convenience shorting switch S4 permits one or two of the storage capacitors to be disconnected from the charging path if only two or one flash heads are needed during a pho to session Doing this can speed up charging time resulting shorter cy cling intervals between shots Meter M1 monitors the voltage on any selected storage capacitor You can select the storage capacitor to be monitored with S2 The series resis tance of the meter was selected so that a reading 90 of full scale rep resents full capacitor charge The slight overvoltage scale allowance can be useful if high line voltage is ever encountered M
141. le and well organized to help protect your valuable copies from damage Cases and binders designed to hold a year s issues may vary with issue sizes Constructed of heavy reinforced board covered with durable leather like material in color Title hot stamped in gold silver MODERN ELECTRONICS Free personalization foil for index ing year Cases V notched for easy access Binders have special spring mech anism to hold individual rods which easily in This allows magazines to be fully opened for easy readability Jesse Jones Industries Dept Mod E Quantity Cases Binders 499 East Erie Avenue Philadelphia PA 19141 One 7 95 9 95 Pleasesend cases binders Three 21 95 27 95 Modern Electronics Magazine Six 39 95 52 95 1 Enclosed is _ d m x Add 1 per case binder postage 1 Charge my Minimum 15 and handling Outside USA 1 American Express Visa 2 50 per case binder U S 11 MasterCard Diners Club funds only Card Exp Date Signature Charge Orders Call TOLL FREE 7 days 24 hours 1 800 972 5858 Print Name_ _ _ Address No PO Box Numbers Please City State Zip PA residents add 6 sales tax SATISFACTION GUARANTEED ea a ee March 1991 MODERN ELECTRONICS 69 Earn Your B S Degree in ELECTRONICS or COMPUTERS 2 S By Studying at Home Grantham College of Engineering now in our 4181 year is
142. le to mount on tripods or other supports Being able to tilt is also a plus into their respective flash tubes When searching for suitable flash tubes look for ones intended for 450 to 500 volts across them GE No FT 118 and similar types Try to obtain heads that include tubes trigger transformers and suitable reflectors to minimize any modifications need ed to adapt them for light stand use Suitable capacitor values are in the 500 to 800 range These capaci tors should be rated to handle 500 working volts but in a pinch you can get away with capacitors rated at 450 volts You can parallel connect small er value capacitors to obtain the de sired value if need be You also need a power transform er of thetype used to power tube type TV receivers amplifiers or radios The transformer should have a sec ondary winding rated at 650 to 700 volts and a center tap to drive a full wave power supply circuit trans former with no tap on the secondary winding and capable of delivering 325 to 350 volts can be substituted for a half wave power supply circuit Se lect a transformer rated at not less than 50 mA The greater the current 48 MODERN ELECTRONICS March 1991 rating the faster the charging cycle for the flash head storage capacitors and the shorter the cycle interval be tween shooting pictures To avoid confusion we ll deal with the elements that make up this project one at a time discussing how ea
143. led B Slots 8087 Socket 150 Watt Power Supply Deluxe Keyboard Full Size Case tor 4 1 2 HT Drives 1 Year Parts amp Labor Warranty on Base Unit Produced by JCC Add 2nd 360K 5 Add 10MB Drive Add a 20MB Drive 239 3865 286 SYSTEM OPTIONS 512K Upgrade for 3365286 1 Full Meg 99 40MB Hard Drive special MEMORY Upgrade Avail lot 3865 286 CALL 60MB Hard Drive Contoller Dual H0 FD 79 80M8 Hard Drive 1 2 8 or 360K 5 4 Drive 79 110MB Hard Drive Special 720K 3 1 2 Drive 79 LARGER HARD DRIVES AVAILABLE 1 44MB 3 1 2 Deve requres DOS 3 35 99 IRWIN 20M8 Tape Back Up System 20MB Hard Drivc 169 AT amp T 40 MB Tape Backup 30MB Hard Drive 199 AT ParalleV Seria Game Card 386SX or 286 or SUPER SYSTEM OPTIONS DOS 3 1 32 33 01 39 49 69 79 NCR 15 GREEN with NCR Card 99 Parallel or Seniai Cad 19 AT amp T 12 Biack amp White TTL and AT amp T Card 99 VGA Monitor and V 3A Card 398 12 Monochrome Hi Res TTL 59 14 gt RGB Color Mor tor w Color Card 149 Color Graphics w P inter Port 39 Monochrome Graphics Card with Printer Port 39 ORIVE WARRANTIES VARY CALL FOR DETAILS COMPUTER PRODUCTS Computers Acer Altos Apple Citizen Compaq Goldstar JCC Leading Edge Quadrant Mitsubishi NEC Packard Beil Panasonic Samsung Sharp Toshiba Trinity Unisys WYSE CUERO Pricing Available HARD DRIVE
144. ll in light that you use to illuminate the shadows created by the main light This light can be lo cated near the lens axis but is subor dinate to the main light The third and final criterion is independent background lighting that acts as a hair light for a degree of back lighting to separate the subject from the background It can be used as a rim light or side light We offer here two different but similar multiple head flash system designs One provides 300 watt sec onds of power and features a bevy of bells and whistles The other more conservative system provides 100 watt seconds of power and omits some convenience features The ver sion you build will almost certainly be determined by availability of cer tain components EE Se ee rr Se March 1991 MODERN ELECTRONICS 47 Say You Saw It In Modern Electronics Design Considerations A convenient per tube power level for a home studio system lies in the 100 Ws watt second range Such a unit requires power packs that supply 450 to 500 volts dc This is a feasible voltage for home construction and provides a very useful light level There s no need for miniaturiza tion or powering from a source other than the 117 volt ac line for a studio setup The flash heads are intended to mount on light stands the power pack to rest on the floor The flash heads consist of flash tubes with reflectors and a minimum of electronics Trigger transformer
145. lling its special address Without enabling pulses to turn on the various chips data con flicts would occur due to the fact that all peripheral chips are wired in parallel to the common eight bit data bus to which pins 32 through 39 of ICI connect The Call Restrictor requires three enabling pulses The first at address 0 hex 0H is used to enable program device C5 With every ground pulse reads the program information from C5 The second address is at 0 0 hex 0 000 where the same grounding pulses are used to enable IC6 every time you want this chip to sense the DTMF tones across the line Because C6 requires a positive voltage to enable its output one stage of hex inverter C7 is used to convert the ground pulses from C4 into the positive pulses needed by C6 The final address at 8000 hex 8000H uses the ground pulses to enable memory chip C3 Along with the proper read and write ground pulses C4 allows C1 to place infor mation in and extract data from memory chip 1 Also required is the data bus over which eight bit words are read from or written to memory This also in cludes reading of program material from C5 Intel uses the multiplexing technique to use pins 32 through 39 of ICI for both thelow order address bus and eight bit data bus To extract the required address or data information at the correct time octal D type latch C2 is used Here pulses from ALE pin 30 of
146. lvaged and re used in it Using the Project Operating either of the flash units is almost instinctive The flash heads plug into the power pack and a sync cable attaches between the camera and the pack Two of the flash head units should have 10 10 15 foot long Say You Saw It In Modern Electronics cables and be fitted with tilt heads for use as modeling light and back ground rim hair light Locate these flash units at a distance from the camera Tilt heads let you aim light at a subject from various angles The third flash head gets a 6 foot long cable Positioned close to the camera this flash head provides fill in light It doesn t need a tilt head because you ll usually direct its light straight onto your subject from es sentially camera position If you wish you can fit to this flash head a normally open pushbutton switch that can be used to short across the CABLE TV DESCRAMBLERS BARGAIN HEADQUARTERS eJERROLD HAMLIN OAK ZENITH SCIENTIFIC ATLANTA 6 month warranty We ship C O D Lowest retail wholesale prices FREE CATALOG Global Cable Network 1032 Irving St Suite 109 S F CA 94122 NO CALIFORNIA SALES ORDER TODAY 800 327 8544 CIRCLE NO 24 ON FREE INFORMATION CARD trigger capacitor line so that you can test fire the heads from camera posi tion instead of having to reach for the TEST switch on the power pack Whenever you connect and discon ne
147. m II Cat VOIM2 199 play back when activated A Sound Development System Ideal for experimenters and software developers you can make sound files for spoken advisories music sound effects etc Sound files can be played through the headset or Speech Thing external speaker of the functions can be controlled from C BASIC ASM Voice Master Key System II interfaces with your PC through the parallel printer port Increase i ad Productivity Waiting for a file to print can be frustrating unless you have a printer buffer This buffer quickly absorbs your file so you can get back to work fast The buffer quietly feeds the file to your printer withoul slowing down your computer Don t wait order today Holds about 360 double spaced pages Includes power supply so it will hold data even if your com puter or printer 18 turned off Repeat function to print extra copies Free Space indicator 512K Parallel Buffer 129 Cat 512 Serving Computer Users Since 1982 Holds 360 Pages 30 Day Money Back Guarantee 1 800 456 4123 805 524 4189 24 Hour FAX 805 524 4026 330 Central Avenue Fillmore CA 93015 Visa MasterCard AMEX Discover Add 5 50 Shipping residents add sales tax Ad Code 137 2 CIRCLE NO 154 ON FREE INFORMATION CARD iLearn to Modify ANY Software PUTANS Name
148. memory is nonvola tile for over 10 years in the absence of ex ternal power Dallas Semiconductor offers three families of Cyber products with identical contact interfaces The DS6200 series called CyberKey is shaped and sized for a key chain 2 375 x 1 120 inches The DS6300 CyberCards the size of credit cards except for thickness measures 3 370 x 2 125 inches The DS6400EV is an Extra Volume version of CyberCard to pack more electronics see Fig 2 Prices of these Cyber products in 100 piece quantity range from 3 50 for 096200 CyberKey with 64 bit read only memory to 250 for a Cyber Card EV with 4 megabits of memory Receptacles for the Cyber series start at 3 90 in 100 piece quantity Protocol Specific Memories Motorola MOS Memory Products Div P O Box 6000 Austin TX 78762 intro duced a family of synchronous 32K x 9 fast static RAMs tailored for the Motoro la Intel and Sparc microprocessors 70 MODERN ELECTRONICS March 1991 For the 68040 microprocessor the 62940 BurstRAM utilizes the burst memory protocol of the processor The 68040 itself initiates three bursts However subsequent burst addresses are generated internally by the MCM62940 in the same sequence as by the 68040 For the i486 microprocessor the MCM62486 BurstRAM provides a simi lar solution The processor or the cache controller initiates the burst mode but BurstRAM generates subsequent burst addresses imitating t
149. n tific Atlantic Oak Zenith Order yours today 800 962 6836 BUSINESS OPPORTUNITIES MAKE Become an American Electronics Dealer Profit opportunities since 1965 Call Jerry Norville 1 800 872 1371 CABLE EQUIPMENT CABLETV SECRETS the outlaw publica tion the cable companies tried to ban HBO Movie Channel Showtime Descramblers Converters etc Suppliers list included 9 95 Cable Facts Box 711 ME Pataskala Ohio 43062 MISCELLANEOUS ASIAN LADIES want correspondence for friendship marriage SUNSHINE INTER NATIONAL Dept TW Box 5500 Kailua Kona Hawaii 96745 808 325 7707 THAILAND Women Seek Marriage 100 Photo Brochure 2 00 Club Thai Box 0974M Miami FL 33233 ATTRACTIVE ORIENTAL LADIES seek ing correspondence marriage Professional introductions since 1984 Asian Experience Box 1214TZ Novato CA 94948 415 897 2742 INVESTIGATION CAREER Quick home study Become a professional Free informa tion Since 1971 SIR P O BOX 716 PRO VO UTAH 84603 800 272 6680 JOIN the regulars Televisions to fur coats thousands of items all under 10 00 free gift Alaska Outreach Box 33685 Juneau AK 99803 ELECTROPLATING 75 minute video in structs plating chrome nickel gold on small parts With textbook 29 00 or details Regal Publications Box 1071 Provo Utah 84603 1 800 955 6014 VISA MC AX Order Back Issues of Month s amp Year s
150. n to service all computers as you build your own fully AT compatible micro now with 1 meg RAM 20 meg hard drive and exciting new diagnostic hardware and software Jobs for computer service technicians will almost double in the next 10 years according to Department of Labor statistics making computer service one of the top 10 growth fields in the nation Now you can cash in on this exciting opportunity either full time industry technician or in a N computer service business of your own once you ve mastered electronics and computers the NRI way NRI s practical combination of reason why theory and hands on building skills starts you with the fundamentals of electronics then guides you through more sophisticated circuitry all the way up to the latest advances in computer technology Train with and keep a powerful AT compatible computer system plus popular Microsoft Works software Only NRI gives you hands on training with the finest example of state of the art technology the powerful West Coast 1010ES computer As you assemble this fully IBM PC AT compatible computer from the keyboard up you actually see for yourself how each section of your computer works You assemble and test your computer s intelligent keyboard install the power supply and 5 1 4 floppy disk drive then interface the high resolution monitor Your hands on training continues as you install a powerful 20 megabyte ha
151. n be configured strate how games voice video and ultrasonic circuits work to name just a few of the may things you can do with this system The Digital Signal Generator 8088 Computer Experimenter Platform is built on the same circuit board as sembly you used to build last month s Dual Function Generator This keeps the cost to less than 140 for the combination Dual Function Generator Digital Signal Generator 8088 Computer Experimenter Plat form system Circuit Description To generate the digital signal trains in the Digital Signal Generator add on an 8088 microprocessor 8K of RAM 8K of ROM an 8155 I O port timer and the required support circuits are used The circuitry for all this is shown schematically in Fig 2 A and Fig 2 B With this ar rangement digital signal trains are generated by toggling the U 3 output port signals The timer can be pro grammed to produce a variety of March 1991 MODERN ELECTRONICS 27 95 619 55 8169 5 214 5 9Tu 519 219 TIU ors 924 RE 22 OOUNT ots 824 Say You Saw It In Modern Electronics 28 MODERN ELECTRONICS March 1991 18 NOlUN3N35 UNDIS 1 2t 2 9 QN LH
152. n the circuit board assembly six extra solder posts for wiring the telephone line the line to the telephone instrument s to be monitored and the cord from the power transformer When you finish wiring the circuit board assembly including making connections to the six extra solder posts carefully go over all your wir ing checking off the runs on the Master Wiring List Note mark the Master Wiring List From To IC3pin 2 1050 3 1650 4 ICS 4 5 1656 6 IC5 6 7 1050 8 IC5 8 9 IC5 9 10 1 5 10 11 IC5 11 R8 B 12 1 5 12 7 13 1 5 13 6 14 GND 15 IC5 15 R5 B 16 IC5 16 RA B 17 IC5 17 R3 B 18 1 5 18 2 19 1 5 17 1 20 IC4 10 21 1 5 21 23 1 5 23 24 1 5 24 25 1 5 25 26 IC3 28 5v IC4pin 4 1 4 5 8 GND 6 IC4 16 5V 7 1 1 7 5 IC5 20 IC5pin 1 R1 thru R8 T ICS 27 28 5 14 GND IC6pin 1 R9 R RII T 2 R10 R R12 T R13 L RIXR 4 RII B RIZ B 5 IC6 69 GND function and polarity of the six extra solder posts on the board for refer ence later If you made any wiring errors correct them now House the circuit board assembly inside any enclosure that accommo dates it The enclosure can be metal all plastic or metal and plastic Ma chine the enclosure for mounting the circuit board assembly Then drill an entry hole for the cable the wall mount transformer cable through From To 7 XTAL2 R 8 XTAL2 L 10 IC7 2 1
153. ne channels and the many other SERVICES super easy Other useful features RUE ie Convener eps include programmable scanning large built in speaker 110 volt AC or 12 volt DC operation with optional DCK 2 cable VHF capability 108 174 with the VC 20 option dual 24 hour clocks with timer and even voice frequency readout with the VS 1 option R 5000 The R 5000 15 a high performance top of the line receiver with 100 memory channels and direct keyboard or main dial tuning makes station selection 2 1 Wide band scanning receiver easier One hundred memory channels with message and band marker direct keyboard or VFO frequency entry and versatile scanning functions such as memory channel and band scan with four types of scan stop The RZ 1 is a 12 volt DC operated compact unit with built in speaker front mounted phones jack switchable AGC squelch for narrow FM illuminated keys and a beeper to confirm keyboard operation Optional Accessory e PG 2N Extra DC cable inja jajajajaa The RZ wide band scanning receiver covers 500 kHz 905 MHz in AM and narrow or wideband FM The automatic mode selection function makes listening The R ms band all receiver with 10 morbo channels mable scafining dual 24 logks with timer all mode squelch and noise blankers a large front mounted speaker 110 volt AC or 12 volt DC operation with the DCK 1 ca
154. nect the links O between the oscillator microphone preamplifier modulator and output buffer sections Power up the Trans mitter and check the input section with a low level signal from a signal generator Usean oscilloscope to ver ify that proper gain is obtained at pin 6 of U2 If you observe saturation flattening of the signal waveform peaks you may have to install a voltage divider to correct for this After verifying that the preamp circuit is working properly power down the Transmitter and generator Disconnect the latter and plug into the MICROPHONE jack a micro phone Power up the Transmitter once again and speak into the micro phone as you observe the scope dis play You should see a variable am plitude frequency waveform dis played with peak to peak excursions amounting to a few volts Next check out the oscillator sec tion Touch the input probe of your scope to the anode of D3 and note that there should be at this point a square waveform of approximately 1 06 MHz unless you chose a differ ent frequency for the carrier Peak excursion of this signal should be ap proximately 1 2 volts If the signal obtained is considerably off fre quency change the value of C6 to bring it in line Tolerance here may affect frequency Restore the links between the mi crophone preamp oscillator and modulator circuits but don t restore the link between the modulator and output b
155. nesre presented by the row and column at that juncture Forthe 5 button thetone gen erated would be the algebraic sum of 770 Hz low tone group and 1 366 high tone group and for the 7 button the algebraic sum of 852 and 1 209 Hz When DTMF dialing was introduced in the 1960s comparatively large capa citors and inductors were used for gen eration of pure sine wave frequencies Today DTMF keypads use ICs that are under crystal control to generate syn thesized stair step waveforms DTMF equipment like the G8870 DTMF de coder used in the project described in the accompanying article can receive and decodes these stair step signals into its corresponding binary output as list ed in the table It is the binary output given in the last column of the table that is directly coupled over a four bit data bus to the 8031 microcontroller used in the project 9 15 edi Fig B Standard Touch Tone type key pad keys can consist of a matrix of four rows and up to four typically three columns Keys labeled A through D and and f are for special purpose commu nication applications Each key gener ates one tone from the low and high groups to output their algebraically combined waveform Touch Tone Keypad Key Tone Frequencies and Hex Outputs Key High Frequency ID Tone in Hz 697 697 697 770 770 770 852 852 852 942 941 941 697 770 852
156. nically Stay up to date The Enhancement 8 High pyme of HF Signals by Range Receive Polarization Control 8 Digital Signal Processing Working in the Frequency A Communications System Using ona with all the latest developments in the fast paced ransee 3 arrowband world of electronics 1 Transmitter IMD W Interface Your LX oer B Basic Concepts LI anes on Computer 2 m Power Inequity of Scattering Unity Grade the 1750 Meters Spec zer Parameters Spectrum Analyzers Spectrum Analy Act now Subscribe Today Foreign surface 39 95 per year Air mail rates upon request COMMUNICATIONS QUARTERLY a publication of CQ Communications Inc 76 North Broadway Hicksville NY 11801 USA Cable Converters And Descramblers Why Pay a High Monthly Fee For FREE Catalog Call or Write CABLE CONNECTION 1304 E CHICAGO ST SUITE 301 ALGONQUIN IL 60102 708 658 2365 No Illinois Orders ACIDC VOLTAGE AC DC CURRENT PR 400 DIODE TEST Stock No LOGIC TEST 990092 LED TEST GOOD BAD 95 3ODAY LOW BATTERY Warnin moner sack CONTINUITY TEST BUZZER TRANSISTOR GUARANTEE 20 mHzFREQ COUNTER VISA moa KELVIN Electronics 7 Fairchild Ave Plainview NY 11803 516 349 7620 1 800 645 9212 FAX 516 349 7830 SURVEILLANCE TELEPHONE Monttor room conversations 175 00 Monitor room amp telephone conversations 275 00 Diale
157. ntain Ave Dept ME FX Los Angeles CA 90029 CIRCLE NO 37 ON FREE INFORMATION CARD U S CYBERLAB JOINS FORCES WITH NICK GOSS EXTREME HIGH TECHNOLOGY KITS PRODUCTS MATERIALS NOW YOU CAN BUILD YOUR OWN HIGH TECHNOLOGY PRODUCTS HOME AND SAVE MONEY PROJECTS FROM LASERS PC BASED PERIPHERALS AND TEST EQUIPMENT TO RARE EDISON AND TESLA TYPE LABORATORY APPARATUS JOIN THE CYBERLAB TEAM TODAY SEND 2 TO U S CYBERLAB INC RT 2 BOX 284 PRODUCTION FACILITY WEST FORK AR 72774 501 839 8293 VOICE FAX CIRCLE NO 38 ON FREE INFORMATION CARD March 1991 MODERN ELECTRONICS 65 WPC CAPERS Calendar Creator Plus and Top Priority Personal Information Manager Software from Power Up By Ted Needleman I hate to admit it but I m just not the world s most organized person In fact my idea of organization is to have lots of rather neat piles And my idea of filing is to know within two or three piles in either direction which pile has the infor mation I need My position as a mid level manager usually requires me to juggle several tasks at once And where they drop is where they stay at least until the next time I need to access the task again It s notthat I don t havethetools to do the job There s a powerful 386 PC on the desk in my office It has 4MB of RAM and 110 MB hard disk I try not to leave it on very much though While the view from my office window is spectacular I can see most of lower
158. ntering Dual port game card 19 50 360 degree rotation for greater accuracy 6 00 Shipping 4 stabilizing suction cups BUS Trackman 94 50 oneru 800 344 2370 dee Prices subject to change i LANDMARK UTILITIES V2 0 Benchmark test software for PC XT AT 386 amp 486 Determine the effective speeds of CPU MATH VIDEO DISPLAY CIRCUITRY Speed test is easy to use lt incorporates pull down menus kabosa or mouse access and a complete on screen manual for the ultimate in CAT Reader OCR A Trainable Accurate OCR Software for Hand Held Scanners Fully to read any font Monospaced proportional or kerned text Convert any scanned text ASCII format Automatic Text 6950 Merging COD aad 4 00 tfi Technical Challanga 15 fos restocking Allow 10 business days N COR POR ATE D ecks to clear tor c 601 Oakwood Square East Aurora New York 14052 NYS add 8 sales tax APO C nada Hawan 716 655 0400 Puerto Rico additional 85 00 sniping ESTABLISHED 1985 Compatability can not be Quaranseed List Price 295 12 2450 ssam CAT Image 69 50 600 Shining FREE SHIPPING IN NEW YORK STATE 600 some MOST ORDERS BEFORE 2 PM EST WILL SHIP SAME DAY CIRCLE NO 148 ON FREE INFORMATION CARD Express International Inc
159. o be female on the power pack and male on the flash head cable The trigger circuit as brought to the camera carries only 3 4 volts and thus avoids any prob lems in camera handling relative to the higher pack voltages 100 Watt Second Design The elaborate power pack discussed above includes operating conveni ence features and maximizes the en ergy directed to each flash head March 1991 MODERN ELECTRONICS 53 2 lt lt 100 1M n Bur R6 C2 50 2M 800uF 500V R8 180K FLASH HEAD o 12 51 1 2W 117 po T 5 400V NOTE FLASH 1a S2 Plug and socket connections TUBE R5 TEST C repeat for each of 470 S01 three flash heads SYNC CONNECTOR c lt Fig 4 Complete schematic diagram of minimal power pack circuit design whether one two or three heads are used for a photo session The mini mal power pack shown schematical ly in Fig 4 is less versatile but still useful It can apply 100 Ws total en ergy to flash heads and can fire two or three heads provided the charge energy is divided among the heads for a total of 100 Ws With this ar rangement one head could be fully loaded two heads fire with 50 Ws each and three heads share the charge at 33 Ws each Many simplifications are made in the Fig 4 circuit though some fea tures of the Fig 2 300 Ws power pack can
160. o into making a good storage capacitor in its intended application can also make it dangerous A capacitor charged to 75 to 100 joules watt seconds contains considerable energy When discharged in the normal manner into a flash tube you ll hear a very audible snap as the tube fires and a very noticeable amount of heat will be radiated from the flash tube This is because the 100 joules of energy are being dumped into about 6 ohms of tube resistance at a current of 75 to 100 amperes for a few milliseconds The discharge current can vaporize the tip of a screwdriver if a charged ca pacitor were to short it with such an essentially zero resistance shunt Short EE ing session Test fire the system with the TEST button on the power pack or on the fill in light head before start ing to trigger the system with the ing the capacitor with zero resistance can tear it apart internally and create destructive internal heating Don t ever attempt to discharge a capacitor in this manner The proper way to discharge capaci tor is to shunt its terminals with a power resistor carefully avoiding personal contact with the leads or terminals Ex perienced personnel who work around high voltages keep one hand in a pock et or behind their backs to avoid injury and death when working around high voltage high energy storage capaci tors You should adopt this as a work ing rule as well When discharging capacitor
161. ock clock inhibit and shift load logic 34 MODERN ELECTRONICS March 1991 An Example of a Digital Experiment Using the 74LS165 some housekeeping routines the program checks program selector Switch S2 to determine if you want to use a built in program or download a custom program from an IBM com signals to stimulate the 74LS165 and then view the inputs and outputs on an oscilloscope or logic analyzer Signals necessary for this experiment are stored in the Digital Signal Genera tor Digital Experiments ROM Let us look at how simple it is to generate the signals if the program that generates the signals is downloaded from an IBM PC or compatible computer The first signal to be generated is a shift clock The 8155 timer counter is ideally suited for this task There is no need to get into the actual programming steps at this time What follows 15 a flow chart that indicates the simplicity of the process Refer to Fig A as you go along 1 Initialize the 8155 ports as outputs 2 Initialize the timer to produce a square wave 3 Load the timer divider to divide the 3 MHz timer input to produce a 10 kHz square wave 4 Output AA hex to Port A to make it the parallel data input to the 74LS165 5 Output CO hex to Port B to set clock inhibit and SH LD X high 6 Output 80 hex to Port B to set SH LD low 7 Output 50 hex to Port B to set clock inhibit low and SH LD high 8 Turn on timer for 9 counts 9 Turn
162. off timer off 10 Jump to step 4 Connect the signals to the 74L S165 as detailed in Fig and start the pro gram Verify the results shown in the timing diagram with either your scope or logic analyzer The program includes some addition al code to determine the delay between operations Other than this you can see that programming is not complicated and could even be fun to do on your own Try changing the data at step 4 and note the results Check that QH X isthe inverted or complemented QH uri ess ee SS Say You Saw It In Modern Electronics patible If you select a custom pro RAM RAM is principally used to control to the RAM based program gram the program jumps to the one store the programs you download Used in the system is 8251A pro selected and begins generating digital from a PC or compatible computer grammable communication inter signals as required It then loops until After the UART receives the custom face U 2 This device permits down you press the RESET button program the system ROM transfers loading of custom programs into the DATA LINE FROM 8155 OUTPUT AA HEX 10101010 8INARY HIGH DATA LINE 1 FROM 8155 PAL OUTPUT AA HEX 10101010 BINARY LOW HIGH DATA LINE 2 FROM 8155 PAZ OUTPUT AR HEX 10101010 BINARY DATA LINE 3 FROM 8155 PAS OUTPUT AA HEX 10101010 BINARY Low HIGH DATA LINE 4 FROM B155 PA4 OUTPUT AA 10101010 B
163. omentary action pushbutton TEST switch S3 permits firing the charged flash heads to test the sys tem Pressing S3 grounds the trigger capacitors of all connected flash heads to fire the tubes The current that flows in this trigger line is a bit high for camera shutter sync con tacts especially when several flash heads are fired with a common sync switch A simple way to upgrade the firing circuit is to use an SCR to com plete the discharge path of the trigger capacitor s With SCRI connected as shown its anode to cathode cir cuit absorbs the current that flows through the very low resistance trig ger capacitor return path when firing the system In turn SCRI is triggered by the much lower voltage delivered to its gate from the camera shutter contacts SYNC CONNECTOR SOI be any polarized socket for connection from the camera to the power pack trigger interface One side of the sync cable goes to the gate voltage source the other to the gate of SCRI Because the amount of current flowing in this path is very low no arcing or spark ing will occur Therefore no signifi cant wear of the camera sync con tacts will result Power transformer 77 selected for this version of the project has two ad ditional secondary windings The 6 3 volt winding permits use of POW ER indicator while the 5 volt winding is the source for the SCR gate voltage Transformers that don t have these secondary windings can be used but y
164. ons are due to simple MECHANICAL or ELECTRO MECHANICAL breakdowns FACT over 77 million VCRs in use today nationwide Average VCR needs service or repair every 12 to 18 months Viejo s 400 PAGE TRAINING MANUAL over 500 photos and illustrations and AWARD WINNING VIDEO TRAINING TAPE reveals the SECRETS of VCR mainte nance and repair real world information that is NOT available elsewhere Also includes all the info you ll need regarding the BUSINESS SIDE of running a successful service opera tion FREE INFORMATION CALL TOLL FREE 1 800 537 0589 Or write to Viejo Publications 5329 Fountain Ave Dept ME Los Angeles CA 90029 CIRCLE NO 34 ON FREE INFORMATION CARD EARN YOUR B S E E DEGREE THROUGH HOME STUDY Our New and Highly Effective Advanced Place ment Program for experienced Electronic Tech nicians grants credit for previous Schooling and Professional Experience and can greatly re duce the time required to complete Program and reach graduation No residence schooling re quired for qualified Electronic Technicians Through this Special Program you can pull all of the loose ends of your electronics background together and earn your B S E E Degree Up grade your status and pay to the Engineering Level Advance Rapidly Many finish in 12 months or less Students and graduates in 50 States and throughout the World Established Over 40 Years Write for free Descriptive Lit erature COOK S INSTITUTE
165. ope and optional eight channel Logic Ana lyzer module This month s Digital Signal Gener ator add on generates up to 23 simul taneous digital signal trains that will be used as signal inputs for upcoming digital experiments A main feature of this project is that you will be able to start learning about programming the 8088 series microprocessor A limited understanding of program ming though not necessary for these projects will allow you to integrate digital parts that require software in terfacing into your projects An 8088 microprocessor in the Digital Signal Generator comes sup plies all the necessary bus signals permitting the instrument to also be used as a platform to build test and learn about peripherals and pro gramming of the most popular series of microprocessors ever introduced In future articles we will present cart cw WEE EE ENGGM SE 3 m d projects using the 8088 microproces sor in this project as the base proces sor Figure 1 gives an overview on how the various experimenter Labs could be configured Next month we will describe a Prototyping station that connects the equipment together and begin our 26 MODERN ELECTRONICS March 1991 To s at Pm 201 DIGITAL cec ELECTRONICS ovt a LE amp i emt DII DONOR a A dus ANALOG FUNCTION GENERATOR dis
166. ou must obtain the voltages for the POWER indicator and SCR trigger from the main secondary winding we ll show you how this is done later when we discuss the mini mal power pack circuitry Construction Before you can decide on what size enclosure to use for the power pack circuitry collect the major compo nents that must go into it and from their physical sizes determine the di mensions of the enclosure you need Typical computer grade capacitors measure 2 inches in diameter by 5 inches high The power transformer may occupy a similar volume These components dictate enclosure size especially since three storage capaci tors are involved The prototype of this power pack shown the lead photo was built in toal2 x 7 x 6 inch aluminum utili ty box which nicely accommodated the power pack circuitry Note that this enclosure provides ample vol ume for the components and a satis factory control panel layout Re movable 7 x 12 inch panels serve as the sides of the enclosure and all March 1991 MODERN ELECTRONICS 51 Fig 3 These two views of author s prototype of the 300 Ws unit show the zig zag pattern you should use to fit the power transformer and storage capacitors on a minimum of enclosure real estate components attach to the box itself One side wall not removable side panel accommodates the controls and indicators for the project and serves as the top panel of the enclo sure Most majorcomponent
167. ows a simplified outline view of all three kinds Foil gagesare by far the most common They resemble tiny etched circuit boards A film of copper nickel alloy or similar metallic foil several micrometers thick is laminated onto a thin flexible substrate The foil is then etched to produce a grid or whatever pattern is desired Overall re sistance of a typical foil strain gage may range from around 30to as much as 3 000 ohms Gages with a resistance of a few hundred ohms are most commonly used When the gage is distorted the resistance of the foil changes An important feature of foil strain gages is that they can be made with very uniform characteristics They re also FLEXURE J OR SHEAR TORSION Cru ST Fig 1 Important types of mechanical strain durable and light in weight Still another important advantage is that multiple strain gages can be easily made on the same substrate This means a single very thin compact sensor can detect the direc tion of expansion compression and rota tion of a substrate being monitored Wire strain gages are no longer as im portant as they once were Their opera tion is dependent on the well known fact that the resistance of a wire increases as the wire is stretched The wires used to make strain gages vary in diameter from around 12 to 25 micrometers Silicon strain gages employ a bar of sil icon with a thickness of around a 0 25 millimeter Their resistance is
168. pport multi processor operation These pins are not used in this application Address Decoders The 8088 can address 1M of memory The ROM is positioned at the very top of mem ory Starting at F8000 if a 32K ROM is used or FE000 if an 8K ROM is used System RAM is positioned at 32 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics Hard to Find Unique PC Products at Incredible Prices Installs on ANY laptop or desktop in seconds Connect Floppy Drives 3 5 amp 5 25 To Parallel Printer Port In 30 Seconds Flat Adding a disk drive has never been this up your hard disk in easy Imagine attaching a floppy drive to your half the time laptop or desktop computer in under 30 Backpack allows ox 1 seconds even on PCs with built in disk you to connect controllers high density amp Backpack is an external floppy drive that drives to any plugs into your parallel printer port Your printer plugs into the back of the Backpack drive There are no interface cards to install you never even open your computer You can have a single 3 5 or 5 25 drive and use it on all the computers in your office just by plugging it in Backpack drives transfer information to your computer at the same speed as ordinary floppy drives but install in only seconds Connecting a high density 3 5 or 5 25 inch drive to your computer can allow you to
169. pus Dr San Mateo CA 94403 415 345 5900 SAVE MONEY DON T RENT CABLE TV DESCRAMBLERS CONVERTERS amp ACCESSORIES Save hundreds of dollars owning instead of renting from the cable company Easy to order and install Name brands Pioneer Oak Panasonic Jerrold Scientific Atlanta and more We re famous for lowest prices excellent service and immediate delivery All products fully warranted Your satisfaction is 100 guaranteed CABLE READY Company CALL FOR FREE FULLY ILLUSTRATED 16 COLOR CATALOG 800 234 1006 March 1991 MODERN ELECTRONICS 67 Bill SOLID STATE DEVICES A SCSI IT Adapter Ruggedized SRAM and BurstRAM By Joseph Desposito In this column I cover two products that Transfer use specialized devices rather than the Control devices themselves One is a SCSI II con troller and anotherisaruggedized SRAM Logic card New memory devices for high BMIC DATA speed processors finishes it off 82355 BUS SCSI Bus 32 Bit Caching m ma Controller SCSI H Adapter 2 WD33C93B ALWAYS Technology Corp 31336 Via Colinas Suite 101 Westlake Village CA 91362 announced an ultra high speed Extended Industry Standard Architec ture EISA SCSI host adapter This AL 4000 board provides very fast data transfer rates up to 33 megabytes se cond MB s and operates in caching and non caching modes The adapter is for 32 bit 386 and 486 EISA computers The AL 4000 fea
170. r which is cleared and reset for user ap plications after downloading Downloading of custom programs is another good example of the need to develop basic programming skills It requires that all operating parame ters be set via software initialization The only way data is removed and tested is via a polled or interrupt pro gram The system waits for the data stream to begin and then jumps to the downloaded program when the trans mission has been completed Various jumpers must be connect ed to meet the requirements of a stan dard IBM COM format pins 4 5 6 and 20 of P must be connected to gether This is easily accomplished by strapping J1 Data output signals from the computer swing between 12 and 12 volts Resistor R32 diodes D2 and D3 and IC condi tion the input signal so that it is TTL compatible which is a requirement of the 8251A Generator Bus The Digital Signal Generator bus consists of a 40 pin header that accepts 25 mil 0 025 inch diameter wires These wires connect directly to your prototyping station as shown in Fig 2 B Next month we will describe a prototyping station in which two rib bon connectors connect all signals available in the Digital Signal Gener ator directly to a prototyping station that utilizes popular plug in bread boards and a Wire Wrap system The Digital Signal Generator bus consists of the 22 I O lines plus the timer and clock signals from the 8155 The
171. r tap calls you when phone is used 305 00 9r Sma du Range Unlimited 6 month warranty Phone Tap Catalog 3 00 LISTEN ELECTRONICS 603 Elgin Muskogee OK 74401 1 800 633 TAPS amp Available the telephone CABLE TV BOXES Descramblers Converters FREE CATALOG TRANS WORLD CABLE CO 12062 Southwest 117th Ct Suite 126 Miami Florida 33186 800 442 9333 2 5 E 249 converts any scope into a 100MHz spectrum analyzer 60dB display dynamic range SMITH DESIGN 30 day refund VISA MC 1324 Harris Dresher 19025 215 643 6340 CABLE TV DESCRAMBLERS ALL TYPES 800 582 1114 FREE CATALOG ELECTRONICS 7958 Pines Blvd Suite 276 Pembroke Pines FL 33024 80 MODERN ELECTRONICS March 199 MORSE Code No Problem You can in crease your speed no matter how many times you ve failed before Results guaranteed when you follow the instructions PASS Publish ing s CW Mental Block Buster program helps you explode mental blocks that hold you back Based on 40 years of research the CW Mental Block Buster uses guided meditation dynamic visualizations and powerful affirmations to blast through mental blocks You can do code That means new bands more contacts more fun This is not a CW practice tape The CW Mental Block Buster audio cassette and practice booklet are only 24 95 ppd in the US NY residents add 1 87 sales tax Quantity discounts available for classes
172. r uses power to transmit both sidebands and the car rier This being the case efficiency is a maximum of only 33 percent Modulation Methods To build an AM transmitter you need a modulator to multiply a carri er frequency by a modulating signal that contains useful information You can do this electronically with logarithmic conversion and addi tion use of digital to analog D A converters etc Because it s readily available low in cost and easy to implement the project to be de scribed employs the D A circuit for its modulator Operational amplifiers can be con figured to integrate differentiate and amplify signals each function implemented by feedback elements An integrator for example requires a capacitor in the feedback loop If the feedback element is a nonlinear device like a diode or transistor you can design a logarithmic converter like that depicted in Fig 4 A With such a circuit adding the log of two signals and then taking the antilog produces the equivalent multiplied signal In theory this would work but putting it into practice can be a real nightmare The bandwidth con Say You Saw It In Modern Electronics sideration of the op amps would make this implementation prohibi tively expensive and a large number of op amps would be needed to im plement such an arrangement With support circuitry D A con verters can be used for modulation as in Fig 4 B A D A converter can be use
173. rd disk drive today s most wanted computer peripheral now included in your course to dramatically increase the data storage capacity of your computer while giving you lightning quick data access you build a fully AT compatible 8 ncludes AT compatible 20 Meg ES ing c ti N e ackage Plus you now work with today s most popular integrated software package Microsoft Works learning to use its word processing spreadsheet database and communications utilities for your own personal and professional applications But that s not all Only NRI gives you hands on training with the remarkable R A C E R plug in diagnostic card and QuickTech diagnostic software from Ultra X professional state of the art diagnostic tools that make computer troubleshooting fast and accu rate H 2 277777 Your NRI computer training includes all this NRI s unique Discovery Lab for circuit design and testing Hand held digital multimeter with talk you through instructions on audio cassette Digital logic probe that lets you visually examine computer circuits The new AT compatible West Coast 1010ES computer with high speed 80286 CPU 101 key intelligent keyboard 1 2 meg high density floppy drive 1 meg RAM expandable to 4 meg 64K ROM 20 megabyte hard disk drive MS DOS GW BASIC and Microsoft Works software R A C E R plug in diagnostic card and QuickTech diagnosti
174. rder now but please make sure on your mailing list Address ST telephone E Res Specify County Q Check Money Order enclosed Q Charge my Visa MC AMEX Discover Card Exp Driver s License 4 Signature Qty Cat Description Subtotal CA Res Add Sales Tax Central Computer Products Dept 137 2 330 Central Avenue S amp H Price Total 26 00000 to permit use of interrupts if needed for Platform applications Lines A18 and A19 are decoded by U7B A18 and 19 are high the ROM is selected otherwise RAM is addressed Chip U7B decodes the I O addresses Provisions have been made for four I O devices by decoding ad dresses A6 and A7 when the IO M pin 28 of U11 is low I O decoder U7B generates chip select lines at locations 4X 8X and CX The Digital Signal Generator uses Port CX for the U73 and Port 8X for UART U12 e The 8155 I O Port In this project U13 playsa key role The 8155 device consists of two eight bit and one six bit I O ports that can be configured to be either inputs or outputs The six bit port can be programmed to be status pins the eight bit ports oper ate in a handshaking mode Also included is 14 bit timer counter that provides either a square wave or terminal count pulse out puts
175. re mul tiples of the fundamental These fre quencies have phase relationships that can be shown through trigono metric identities to be negative frequencies When the desired signal that con tains the information to be transmit ted is multiplied by a high frequency carrier modulation is the result During modulation the baseband signal being shifted up in frequency centered at the carrier frequency f Modulation also creates a copy of this signal shifting it in the negative direction as a negative frequency as shown in Fig 1 B Notice that the modulated signal at fe contains both upper and lower sidebands Recall that the shifted spectrum at f has what was once the negative and positive profiles of the speech spectrum Consequently it contains redundant information since only one profile is needed to convey the desired information Therefore filtering out one of these humps won t diminish the transmit ted information The process of filtering out one of the humps is where single sideband gets its name from After filtering is accomplished only one sideband re mains to be transmitted as illustrat ed in Fig 1 C Double Sideband Asits nameindi cates DSB transmits both sidebands dant information the design of the DSB transmitter is simpler than the SSB transmitter Without sideband filtering the transmitter is less costly and easier to build At the destina tion though the receivers
176. rinter you re using Calendar Creator Plus can generate cal endars of up to 11 by 17 inches Most of your calendars however will be printed Priority gee the Things Puar on on letter or legal size paper or the special paper Power Up offers for several sizes of organizers The sharpest and most at tractive calendars are generated on a laser or Hewlett Packard DeskJet printer but the software does support almost any dot matrix printer that can emulate Ep son or IBM graphics For the past several months however I ve been using a couple of packages from Power Up that let me have the best of both worlds Calendar Creator Plus and Top Priority can operate in conjunction with each other on the PC or Macin tosh but they re also a very useful ad junct to my manual organizer which is the way I usually use them Both Power Up programs are similar in packaging and documentation They come with both 5 25 and 3 5 inch disk ettes and a booklet style manual of about 50 pages or so Each separate manual is organized along the same lines explain ing what the program does and taking you through set up and use of the pack age The manuals are well written and have lots of illustrations both containing screens you ll encounter and reports that you can generate Calendar Creator Plus CCP as its name implies allows you to print custom calendars that reflect your appointments deadlines and ot
177. rmation below Credit Card Number Expire Date Print Full Name Signature EE Say You Saw It In Modern Electronics HUGE COMMUNICATIONS CATALOG 88 pages including amateur shortwave and scanner equipment Universal Radio 1280 Aida Drive ME Reynoldsburg OH 43068 COMMUNICATION AT ITS BEST AR 900 234 AR 1000 453 BC 200XLT 269 BC IO0XLT 215 BC 800XLT 266 BC 760XLT 290 BC 210XLT 199 plus low prices on CB s and RADAR DETECTORS TURBO ELECTRONICS PO Box 8034 Hicksville NY 11802 Questions Welcomed 516 938 1946 CABLE TOCOM VIP TEST CHIP For Models 5503 VIP and 5507 Unlike any other turn on this one works Easily installs in just seconds 50 00 each No Calif sales Call 213 867 0081 CABLE DESCRAMBLERS Jerrold 400 450 Tri Bi SB 3 Scientific Atlanta Oak To com Lowest Prices Example Jerrold from 25 00 No Calif Sales Call us last and see 213 867 0081 ZENITH Z Tac Special test board installs easily in minutes and turns on decoder for all modes Great for flashing problems Only 50 No Calif Sales Call 213 867 0081 FOR SALE DESCRAMBLERS brands Special Combo Jerrold 400 and SB3 165 Complete cable descrambler kit 39 Complete satellite descrambler kit 45 Free Catalog MJO IN DUSTRY Box 531 Bronx NY 10461 0208 CABLE TV EQUIPMENT CABLE TV converters and descramblers dis count center Jerrold Tocom Hamlin Scie
178. s Frequently a pcb is made available for purchase at a modest price This is noted at the end of the article s Parts List If it isn t listed you have to make your own board from the plans pictured or go to point to point connections with say wire wrapping If there are a lot of components in the circuit or you wish to make as compact a product as you can the pcb route is the most desirable one to take There are many waysto do this as evidenced by the host of articles on the subject that we presented over the years Having a foil pattern pub lished here makes it real easy But what if you don t have one Again we ve presented ways to roll your own that are simple to do Simple and effective that is if your parts count isn t great or you don t care about laying out a pattern in the best way to conserve board space requirements or you only plan to make one board rather than a number of them that might require another company to produce them on automatic production equipment If you deal with a rather complex cir cuit and or wish to hold down the size of a board as much as possible you may turn to computerized pcb layout programs They re indispensable for profes sionals But CAD computer aided design methodologies call for a soft ware investment that ranges from moderate 100 to 500 to high thousands of dollars Furthermore there s a rather steep learning curve for the higher priced ones which give you great
179. s and trigger capacitors are the only trigger components in the flash heads The remaining triggering cir cuitry is housed inside the power pack which is the major element in the system since it encompasses the storage capacitors charging power source control and monitor ele ments and triggering circuitry To obtain effective energy light conversion a full amount of energy should be supplied to each flash tube in a multiple head system To achieve this the applied potential must be at least 400 volts but not more than 550 volts for reliable firing You must take care to avoid subjecting the flash tube to greater than 550 volts or the tube will be irreparably dam aged From the foregoing you can see that there s a very definite voltage window between 400 and 550 volts that defines power pack voltage levels The power pack must there fore bedesigned to load the tube to a 100 Ws energy level within these voltage limits Also each flash tube should be loaded to this energy level whether one two or all three flash heads are in use for a particular pho to session This is accomplished with a separate storage capacitor in each flash head These capacitors charge in parallel from a single source but they re electrically isolated from each other for independent discharge MU Fig 1 Flash heads selected should have built in flash tubes and trigger trans formers They should also be ab
180. s data communications data management and waveform graphics It uses standard phones a Hayes compatible modem and an RS 232C interface between a Tektronix 2230 Portable Digital Storage Oscilloscope and an IBM PC XT AT or compatible or two DSO s With this computer service waveforms can be transferred to a service center for further analysis speeding field troubleshooting This is a lot better than trying to describe some complicated waveforms verbally Software price is 295 ee gt 8 MODERN ELECTRONICS March 1991 Say You Saw It In Modern Electronics The Upgrade Specialists 90 s Power MPUTERS THE POWER OF NEW SYSTEM FOR A THIRD OF THE COST VANTAGE 386 25 MHz 699 00 FEATURES Made In USA 2 year warranty 48 hour burn in Chlps and Technology chipset INTEL 386 25 processor Shadow Ram AMI BIOS with bullt In Diags Up to 8 Megs on board Simms PERFORMANCE Landmark 33 Norton 28 2 MIPS 4 33 COMPATABILITY Supports DOS 05 2 WIndows 386 Deskview 386 UNIX NOVELL VANTAGE 486 25 MHz 1999 00 FEATURES 80486 25 MHz CPO Rev Cl Bugless Version 8 16 bit AT slots 8 KB internal cache memory Burst Mode support Up to 16 MB onboard memory 2 year warranty Made In USA PERFORMANCE BENCHMARKS LM 114 10 SI 38 80 MIPS 10 97 BULLET 286 MOTHERBOARDS 5 8 slot models for PC or XT Uses your PC and
181. s use well insulated clip leads attached to a 10 watt resistor of say 500 ohms resistance At tach one clip to one terminal of the capa citor Then carefully touch and hold the other clip to the remaining terminal for several seconds Repeat the procedure several times to make sure the capacitor is fully discharged even if you re working circuit that hasn t been powered for hours or several days Work with one hand only remove any rings and watches before you start and an alert apprecia tion of what charge can do And always handle any capacitor as if it s fully charged to a lethal voltage An integrating flash meter is a very useful accessory and is highly recom mended when using this project Place the meter at the location of HVM7K 75 000 Volt DC Variable Output Lab Source Kit 5 5 1063 Ray Gon Kit project energy without wires camera sync contacts your subject and aim it toward the NIG9K 12V 115 VAC Hi Out Neg fon Generator 8 x EMATK Telekinelic Enhancer Electric Man Assembled When you re donetaking pictures camera while you test fire the system LGSK Lightning Display Globe Kit BTC1K Worlds Smaltest Tesla Coil Kit BTC3K 250KV Table Top Testa Coil Kit BTCS 1 5 Million Volts Tesla Coil Plans Jacobs Ladder 3 Models Plans GRA1 Anli Gravity Generator Plans PFS20 Plasma Fire Saber Assembled The
182. s be ing placed the EPROM program in structs the 8031 to ground pin 3 This cuts off and deenergizes When the relay contacts open the telephone line connection is auto matically broken After 2 seconds ICI re applies a logic 1 to pin 3 to re activate the relay and restore dialtone Any number dialed to make an outgoing call that the project will permit is stored in memory in the Call March 1991 MODERN ELECTRONICS 23 Restrictor When you hang up means must be found to have 1 erase the current number before you can dial another number to avoid conflict This is accomplished by Tel tone line sense relay RY2 shown in Fig 3 D whose internal contacts close every time a telephone instru ment is lifted off hook By connecting one side of RY2 to ground and the other side to PORTI pin 2 of C1 the 8031 can act upon the hang up signal If PORT1 senses ground condition at pin 2 JC is in structed to erase the current number from memory Operation of RY2 is straightfor ward This relay senses the current flow when the contacts of are closed and the handset of the tele phone instrument is taken off hook When both sets of contacts are closed a conductive path is created for the dc voltage coming from the tele phone line to flow This causes RY2 to energize and close its contacts just before a new number is dialed The Call Restrictor requires a 5 volt 100 mA dc supply for opera tion
183. s from that of the sur face to which it is bonded Changes in temperature can also cause uneven ex pansion of either the surface or the gage thereby giving rise to an erroneous indi cation of strain The easiest way to solve both these pro PE ITA AL ES LE RTT Say You Saw It In Modern Electronics BUILD A DIGITAL STORAGE SCOPE As Part Of The Complete Modern 199 95 Electronics Computer Lab Vertical Sensitivity 01 v div AC DC Coupled Ext Trigger Input Single Sweep Mode Screen Freeze Mode 199 95 Postage amp Handling 6 50 OPTIONS Add an 8 channel Logic Analyzer and view up to 8 digital signals simultaneously perfect FEATURES 20 Mhz sec Sample Rate 5 us to 5 sec div Sweep Rates LCD with 64 x 240 Dot Resolution Provisions for Adding Optional Second Channel Requires 5V 12V Power Supply for viewing CPU Bus signals Postage amp Handling 53 00 Power Supply Kit 34 95 4 00 PH Matching Black Steel Cabinet 37 50 4 50 PH Deluxe 100 Mhz Scope Probe with 10 1 Switch 27 50 3 50 P H EXPAND YOUR LAB Add A Dual Channel Function Generator With An Add On 23 Channel Digital Signal Generator The Function Generator features two separate Sine Triangle Ramp and Square wave generators 10 Hz to 100 Khz Ideal for upcoming Analog and Modulation theory experiments Requires SV 12V Power Supply 69 95
184. s mount on the other side wall which also serves as the floor of the enclosure On one end of the enclosure should go the sockets for the cables that con nect the flash heads to the power pack No actual chassis is needed since all components mount to either the enclosure walls or on small ter minal boards If you use the utility box described above position the storage capaci tors and power transformer in a zig zag pattern see Fig 3 to fit theavail able area on the bottom panel Plan on using ring clamps for mounting the capacitors and 14 inch spacers to support the transformer so that its leads can fan out under the trans former and obviate the need for drill ing extra holes Plan your layout so that two small terminal boards mount near enough to the power transformer so that its leads reach the appropriate points on the boards without requiring you to extend them with wires Mount on one terminal board the components associated with the high voltage rectification section namely the rectifier diodes filter ca pacitor C7 and resistors R4 and R5 On a second terminal board that will mount near the transformer mount D6 C5 R7 and R6 with SCRI R9 and D7 at one end of the board Mount on a third terminal board D3 D4 D5 RI R2and R3 The resistors on this last board are 10 watt units that operate at nearly 500 volts Usea high quality board material and leave 4 inch of space between the re sistors and the surf
185. s the output voltage to de crease This operating mode can be re versed by transposing the positions of R3 and R4 The 741 op amp is readily available and inexpensive Much better op amps are VOLTS Fig 5 How to connect a strain gage to a Wheatstone bridge available and these should be used for precision applications Many other strain gage amplifier circuits are available as well You can find them in application notes published by strain gage makers and manufacturers of op amps Do It Yourself Strain Gages It s possible to make strain gages using commonly available materials and sup plies Years ago I was studying the move ments of a small guided rocket in a home made wind tunnel that was strapped to theside of my car I needed a way to mea sure the displacement of the rocket in re sponseto guidance commands The rock et was mounted on a stiff length of piano wire that flexed when the rocket moved The obvious solution was to attach a strain gage to the piano wire But I didn t have a strain gage The solution to this measurement prob lem was deceptively easy First I coated all but the ends of the wire with a layer of insulating paint After this layer of paint dried I applied a coat of conductive paint over the insulating paint and the exposed end of the wire to which the rocket was at UR C C P M 62 MODERN ELECTRONICS March 1991 Say You Saw It In
186. smitters communications and much more Catalog 3 00 DSP P O Box 1275 ME Redondo Beach CA 90278 DIGITAL AUDIO SAMPLER Digitally re cord and playback any audio source with spe cial effects Microprocessor controlled elec tronic project For detailed plans send 10 00 to P O Box 341 Dearborn Hts MI 48127 CABLE Converters ALL MAJOR BRANDS For information amp orders call 1 800 782 0552 e FREEWAY INC s m p Box 5036 Burnsville MN 55337 BUILD from easy to follow schematics audio mixers equalizers stage studio business home basic to sophisticated feedback con trollers active filters guitar super fuzz box loudspeaker enclosures including car van power supplies more vSSE reliability Send 5 00 for descriptions Reasonable prices von Sprecken Sound Engineering Dept C Box 1315 Clinton MS 39060 SURVEILLANCE COUNTERSURVEIL LANCE Guaranteed lowest prices Unbeliev able Detectors Jammers Transmitters Phone Security Cameras Personal Protec tion Books More Huge catalog 5 00 Re fundable PROTECTOR Box 520294 Salt Lake City UT 84152 50W SUBWOOFER Add awesome bass to your home stereo system This is an excellent performing component not cheap junk Complete plans 18 00 C Rotthoff Box 70 Atlanta GA 30274 FREE CATALOG Save hundreds on sought after electronic electro mechanical and com puter related hardware and components in
187. st science fair enthusiasts and mad scientist ex perimenters not to mention the ordinary hobbyist experimenter in its diversity of topics Among its 55 space age projects you will find a plasma sphere Van de Graff generator Tesla coil and Kirlian photography He Ne and solid state laser experiments and projects optical data link variable rate xenon strobe see in the dark viewer experimenting with su perconductors and biometal materials espionage devices robotics and more Operating details schematics parts lists construction hints and where to obtain unusual parts are provided The only shortcoming is that no pc guides are pro vided but a big plus is an appendix that gives full names and addresses of sources of supply and further reading No less than three offerings come from Delton T Horn all published by Tab Books and all soft cover The Compara tor Book 185 pages 15 95 offers 49 projects a comparator generator light and dark detectors window comparator two bit flash converter temperature range detector and more The Thyristor Book 205 pages 16 95 offers four layer diode and laser circuits alternative dc power controller triac demo circuit triac light dimmer light cross fader self activated night light digitally controlled ac switch and u d llli nM E S Say You Saw It In Modern Electronics light dimmer and wide range timer 49 Easy Electronic Projects 216
188. t Thus power is applied and removed in the same sequence every time the card is inserted and withdrawn affording an ex tra margin of safety to stored data Static electricity discharges through the ground pin before the signal pins make contact Say You Saw It In Modern Electronics safeguarding the integrated circuits in ternal to the card from electrostatic dis charge ESD In addition all contacts are recessed to keep away other sources of static electric ity such as finger contact Intended for use in rugged industrial environments CyberCard is ultrasoni cally welded to form a rigid enclosure With the number of contacts reduced to just five and the gold plating removed normal pressure on the contacts was in creased to break through dirt and films found in the industrial environment In contrast a card with 68 high pressure contacts would have intolerable inser tion withdrawal force and quickly wear away the gold plating Organize and Protect Your Copies of Wi MODERN ELECTRONICS Now there s an easy way to organize and keep copies of your favorite magazine readily available for future reference Designed exclusively for ME by Jesse Jones Industries these custom made titled cases and binders provide the lux ury look that makes them attractive additions to your book shelf desk or any location in your home or office Whether you choose cases or binders you ll have a storage system that s durab
189. t Avenue NW Washington DC 20008 NEW Training now includes Ultra X e is a registered trademark of International Business Machines Corp diagnostic hardware and software for quick QuickTech are registered trademarks of Ultra X Inc accurate troubleshooting Now you train with and keep the SEND TODAY FOR FREE CATALOG latest in diagnostic gno hardware McGraw Hill Continuing Education Center MFI 4401 Connecticut Avenue NW Schools Washington DC 20008 x and software the extraordinary R A C E R plug in diagnostic courses card and QuickTech diagnostic S CHECK ONE FREE CATALOG ONLY WM approved software both from Ultra X Microcomputer Servicing 0 Computer Programming nder m 1 nftha utomotive Servicing Locksmithing ill chec Using these state of the art Systems Analysis 1 Paraglegal for details tools you learn to quickly Li Industrial Electronics amp Robotics 1 Electrician 1 C PC Software Engineering Using Building Construction dr ter C Telecommunications O Desktop Publishing amp Design problem on XT AT EGER Word Processing mome Business 11 TV Video Audio Servicing cer rc ptm Electronic Music Technology Bookkeeping amp Accounting 80286 80386 and E M C Fiction Nonfiction Writing C Basic Electronics compatible machines You discover how to use the R A C E R
190. t ra dial Resistors 4 watt 5 tolerance R25 R26 510 ohms R27 10 000 ohms R28 R29 1 000 ohms RS1 Five resistor 10 000 ohm resis tor SIP RS2 RS3 Nine resistor SIP Miscellaneous S1 Spst normally open momentary action switch S2 Seven position DIP switch J9 Three position single in line header J10 Power connector J11 five position single in line header J12 J13 40 pin socket strip P1 DP 25 connector Printed circuit board suitable cab inet see Note below etc Note The following items are available from Netronics R amp D Ltd 333 Litch field Rd New Milford CT 06776 tel 203 355 2659 For Digital Signal Generator Complete set of electronic compo 10 000 ohm nents mount on last month s Dual Channel Function Generator pc board 69 95 P amp H Optional 5 and 12 volt power supply kit one required for both Generators 34 95 4 P amp H Optional black steel cabinet for combination Function Digital Sig nal Generator 37 50 4 50 P amp H Also Available from Netronics R amp D Ltd For Digital Storage Oscilloscope January 1991 Complete set of electronic compo nents including pc board but cabinet power supply or probes 199 95 6 50 P amp H Optional eight channel Logic Ana lyzer 59 95 3 P amp H Optional 5 and 12 power supply kit 34 95 4 P amp H Optional IC socket kit contains 33 sockets 9 50 1 P amp H
191. t the legends Again allow each coat to dry before spraying on the next coat Mount the various components and subassemblies in their respective location Then refer back to Fig 2 to wire together the circuit Take care when doing this to properly polarize the electrolytic capacitors and diodes and properly base the SCR Make certain that the connections to the sockets into which the flash head ca bles plug are properly polarized Wire the ground and trigger capa citor feeds in parallel Be sure to feed the high voltage leads independently to each storage capacitor since each flash head has its own separate storage capacitor A word of caution Electrolytic ca pacitors that have been sitting around unused for a long time have a tendency to lose storage capacity and must be re formed before they be have properly An unformed capaci tor won t fully charge and may heat internally if excess current is applied to it Forming isn t difficult but it must be performed before you try to Say You Saw It In Modern Electronics put the power pack into service Your wired power pack includes everything you need to form the stor age capacitors as follows Resistor R10 at the input of switch 54 is in cluded just for the forming proce dure Opening 5 inserts 10 the charge path to limit charging current when forming the capacitors Forming is a straightforward pro cess With the flash heads discon nected from the power pa
192. tandard AM spectrum Thus for a 1 5 MHz 1 500 000 Hz carrier effective antenna length is calculated as follows c f 300 000 000 1 500 000 200 meters 3 3 At 200 meters in length this consid erable improvement over the 60 000 meter antenna length needed to trans mit the 5 kHz signal directly If the carrier frequency is further increased to 30 MHz only a 10 meter long an tenna would be needed for transmis sion and reception of the signal Modulation is the key to transmit ting useful low frequency informa tion on a high frequency carrier This is done by electronically com bining the two frequencies so that they produce a composite signal that s then radiated from the trans mitting antenna Amplitude Modulation Many forms of modulation are cur rently used for transmission and re ception of radio waves including amplitude modulation AM fre quency modulation FM pulse mod ulation PM pulse code modula tion PCM etc Our focus here is on AM which includes such techniques as single sideband SSB double Say You Saw It In Modern Electronics sideband DSB and double side band with carrier DSB C Each technique has its advantages to re commend it as well as its unique drawbacks To understand the dif ferences between these techniques we ll discuss each in turn Single Sideband SSB is a type of signal that s transmitted with only one of its side bands
193. that you ve as signed a priority to a particular task You can also use Top Priority for a simplified project tracking and manage ment system The software allows you to define a task as a subtask These sub tasks are components of a larger overall task which then becomes a goal For example the goal of writing this col umn could be broken down into a num ber of subtasks such as decide what to write about this month obtain pack ages install packages pack ages etc This lets you break large tasks down into smaller tasks which are simpler to track You can also use the field provided for Category When you enter something into this field you can filter your lists and print only those categories you re inter ested in Top Priority even has a note that allows you to append up to 630 characters to an entry Accessed by press ing the F4 key this feature is useful for leaving yourself a reminder I generally use it when I schedule a follow up call for several weeks in the future You can run Top Priority in TSR ter minate and stay resident or stand alone mode When installed as a TSR the LT T key combination brings up the program You can then add to your lists or edit them You can also view the To Do To day screen Because I don t like to leave my office PC running I generally use the software in stand alone mode and print th
194. the KEX M900 The optical link in creases S N reduces distortion and upgrades sampling rate and D A conversion to eight times one bit Fulllogic control and an SLX head are featured in the cassette section The head provides increased tape pressure to increase the magnetic field and minimize dust build up and con tains oxygen free pure copper wire that improves linearity and reduces signal loss Other features include a dual azimuth head music search and Dolby B C noise reduction A one button smart remote con troller permits a button to be pro grammed to perform a selected fre quently used task that is not already present on the controller This Detachable Face Security sys tem permits removal of the faceplate that contains all buttons and con trols leaving only a blank faceplate in the dashboard to deter potential thieves 1 200 CIRCLE NO 6 ON FREE INFORMATION CARD OAK M35B COMBO 539 95 amp MORE OUR PRICES ARE BELOW WHOLESALE CABLE DESCRAMBLERS Jerrold Zenith Hamlin Sci Atlanta Pioneer CABLE PLUS 14417 Chase St 481 C Panorama City CA 91402 1 800 822 9955 Other Info 1 818 785 4500 NO CALIF SALES DEALERS WANTED CABLE TV CONVERTERS Attention Cable Viewers Jerrold Zenith Oak Scientific Atlanta Hamlin Tocom and many others Ch a BEST PRICES 1 800 826 7623 S B amp B Inc 4030 Beau D Rue Dr Eagan MN 55122 ADVERTISERS INDEX
195. the tube that must be dissipated between flashes How ever the charge time of the power pack is more of a limitation than the allowable repetition rate of the flash tube So the power supply itself will be the determining factor for flash repetition rate Storage Capacitors Having estab lished that a transformer secondary potential of 350 volt rms or a full wave 700 volt center tapped secon dary winding will provide a peak po tential near 500 volts the next step is to select suitable storage capacitors So called computer grade electrolyt ic capacitors of good quality low in ternal series impedance are suitable Your objective is to operate the flash tube near its full watt second rating for maximum energy to light output efficiency Loading is related to the voltage across the capacitor and its value in microfarads by the equation Ws CV where Ws is the energy in watt seconds C is capacitance in microfa rads and V is the charge voltage in kilovolts With 500 volts avail able Ws 0 125 C Thus 500 F de livers 62 5 Ws 600 F provides 75 Ws and 800 F supplies 100 Ws A 1 000 4F capacitor is a bit large de livering 125 Ws which is the absolute maximum rating of the tube How ever 1 000 F capacitor could be ef fectively used if the power pack volt age turns out to be a bit lower than the 500 volt peak being discussed 300 Watt Second Design The power pack circuitry for the more e
196. tifier circuit charges storage capacitor to 100 Ws somewhere beyond 450 volts READY lamp 72 shunted across part of the resistive voltage divider made 54 MODERN ELECTRONICS March 1991 R6 2 megohms l watt carbon R 8 180 000 ohms watt carbon Miscellaneous panel lamp assembly with built in limiting resistor I2 Neon lamp S1 Spst toggle or slide switch S2 Spst normally open pushbutton Switch SO1 Polarized jack T1 350 volt power transformer Suitable enclosure ring clamps for capacitors terminal boards bayonet fuse holder ac line cord with plug materials for flash heads see 300 WS Parts List carrying handle spacers machine hardware hookup wire sol der etc up of R7and R6 indicates when C is charged but doesn t indicate voltage as charge progresses It lights only when a preset charge is reached TEST switch 52 across the 150 volt trigger bus lets you test the flash sys tem as in the Fig 1 circuit Three output sockets are included in this design to permit you to connect mul tiple flash heads to the power pack with the same head circuit as used in the more elaborate design How ever the total 100 Ws charge on a single storage capacitor is all the en Say You Saw It In Modern Electronics T LL ODD D DDDDDDEELUDUDCOLTOC DLCOOOQO GULSSSOLLLLLOIOAAAA A L LLLAtXG l OAMOAALAARL 1 io Ennii
197. times higher in frequency About the Circuit The Call Restrictor is a fairly com plex electronic device Because of this the overall schematic diagram is broken into five sections as shown in Fig 3 A through E Section A il lustrates the wiring required for 8031 controller 8K memory C3 and 3 to 8 line decoder C4 that is used to enable C3 EPROM C5 in section B and DTMF receiver chip C6 in section C Also shown in Fig 3 C is the tran sistor driven relay that inter rupts and restores the telephone line connection Figure 3 D shows the wiring for a second relay RY2 used 20 MODERN ELECTRONICS March 1991 BIAS CIRCUIT CHIP REF CHIP HIGH GROUP BIAS POWER FILTER DIGITAL DETECTION ALGORITHM ZERO CROSSING IN DETECTORS IN GS LOW GROUP a od E fal 25 gt HM NN ea 9 A 9 d lt 0 8 3 5 i N 2 8 5 5 5 4 9 4 2 o fal a Cin PG pt 4 il R 13 2 25 9 mt ry z Say You Saw It In Modern Electronics Function 1 IN Noninverting Input 2 IN Inverting Input 3 GS amplifier for connection of feedback resistor 4 Vref to mid rail 5 IC Internal Connection 6 IC Internal Connection 7 OSCI completes internal oscillator 8 OSC2 Clock Output see p
198. tors RJ through R8 in Fig 3 B apply a con stant 5 volts to the eight address data lines Section C of Fig 3 shows the in terfacing required for the Call Re strictor Points C and D connect di rectly across the incoming telephone line as shown in section D Because of the characteristics of the differen tial amplifier at pins 1 and 2 of 6 the direct connection between the two causes no ill effects to the tele phone line The differential amplifier also provides the FCC mandated line to equipment isolation Note that C6 wires across the tele Say You Saw It In Modern Electronics c Fig 3 B phone line through C C2 R9 and RIO Only tones generated by the tel ephone instrument are permitted to enter C6 After processing by inter nal filters and converters out puts at Do through D3 pins 11 through 14 the binary equivalent of the input tones This is the data JC reads and acts upon when the need arises Because of the way C6 is wired data information is always at the da ta output of this chip even when no button on the keypad of the tele phone instrument is pressed To sur mount this C6 is equipped with a STROBE line at pin 10 which is at log ic 1 only when a valid tone pair are in troduced at the input of this chip Hence 1 is programmed to accept the output from only when pin 10 of C6 is high The 8031 has e
199. ts involved in charging average less than 1 am pere ordinary hookup wire will do for these portions of the circuit However the discharge path from storage capacitors to sockets to flash heads carry current pulses of 75 to 100 amperes for a few milliseconds necessitating use of heavier wire No 180r heavier duty and well insu lated at the minimum Locate the holes for the three sock ets into which the flash head cables plug in one end wall of the enclosure When you finish machining the en Say You Saw It In Modern Electronics closure deburr all holes drilled and punched to remove sharp edges Thoroughly clean all exterior sur faces of the enclosure with scouring powder and fine steel wool Then thoroughly rinse the enclosure and dry it The scouring powder and steel wool will have left behind a fine to which paint will adhere Spray a light base coat of enamel paint in your choice of color on all ex terior surfaces and allow it to com pletely dry preferably two or more days Then lightly rub the painted surface with dry steel wool and wipe away all dust Spray onto the first two or more light coats of the paint allowing each coat to thoroughly dry before spraying on the next When the paint has completely dried use a dry transfer lettering kit to label appropriate legends at the control connector and indicator lo cations Follow up with two or three light coats of clear spray acrylic to protec
200. tures a very large cache memory up to 32 MB and is equipped with an 80286 microprocessor that serves as a data manager and cache controller Fig 1 The microprocessor Cache Memory 0 to 32 MB CPU 80286 Floppy Disk Controller ff WD37C65C Boot PROM amp Interrupt Logic FLOPPY Fig 1 ALWAYS Technology s AL 4000 EISA SCSI host adapter features a very large cache memory and is equipped with an 80286 microprocessor that serves as a data man ager and cache controller utilizes a separate bus with 128KB of SRAM and two EPROMS This separate control bus allows the AL 4000 to achieve very high transfer rates and facilitates its use as a non caching adapter The AL 4000 utilizes a unique technol ogy called burst mode transfer This feature of EISA offers ultra high speed transfer rates by allowing data to be buf fered or held in the cache and then transferred across the 32 bit bus at mini computer speeds Burst mode transfer technology re quires large amounts of memory so AL WAYS equipped the AL 4000 with eight SIMM sockets that accommodate up to 32MB of user installed page mode cache memory Either 256KB 1 or 4MB memory chips can be installed To ensure continued EISA compatibil ity the ALWAYS host adapter uses an Intel 82355 Bus Master Interface Con troller BMIC to provide the interface with the EISA bus The AL 4000 supports systems that in corporate additional disk drives and mul
201. uating their work for publication It is particularly gratifying that you have chosen to con tinue publishing the fine works of Forrest Mims III during a time that he has suf fered from the ugly discrimination of other magazine editors We continue to enjoy Modern Elec tronics and intend to renew our sub scriptions Atlee Kohl Irving TX just read your January Editorial and couldn t believe what Scientific Ameri can is doing these days This country was founded by people of diverse religious beliefs who toiled to make sure our free doms would be for everyone My person al belief is that Mr Mims is one of the most respected men of our time To crush his pen would surely set us back into the Dark Ages Robert DeVincent Jr Provo UT If you have any thoughts comments or other feedback you would like to Share with us or our readers feel free to jot them down and send them to us Ad dress all correspondence to Modern Electronics Letters Editor 76 North Broadway Hicksville NY 11801 lt gt Say You Saw It In Modern Electronics MCM ELECTRONICS 650 CONGRESS PARK DR CENTERVILLE OH 45459 4072 A PREMIER Company MCM ELECTRONICS CATAL OG The Swiss Army Notebook Computer MCM Electronics A Well Balanced Parts Catalog If all you want is a huge assortment of high quality parts and components we can tip the scales in our favor in a flash After all we stock more than 16 0
202. udio jazz club concert hall or stadium ef fects through digital recreation of di rect and indirect reflections Three digital EQ functions can be tracked on a dot matrix LCD display A sev en band digital graphic equalizer fea tures six user presets and a digital three band parametric EQ permits equalization of three bands each in the front and rear channels in 4 oc tave increments from 20 Hz to 20 kHz Digital parametric bass and tre ble control can be used in conjunc tion with these functions Pioneer s Supertuner IV quartz PLL electronic tuner is featured in the AM FM section Twenty four presets and best station memory are provided The tuner scans the bands to select and set the six strongest sta tions in an unfamiliar area An exclusive one bit zero cross distortion free D A converter with double step noise shaping prevents generation Of zero cross distortion for improved conversion accuracy nina and low level linearity An eight times oversampling digital filter pro vides extremely low distortion and accurate phase linearity Used with Pioneer s 50 multi play changer the CD section can be programmed for up to 32 se lections from each disc in a six disc magazine The memory permits up to 72 individual disc titles to be pro grammed the titles appearing in the digital display during play An optional optical link transmits the digital audio signal from a Pio neer multi play CD changer to
203. uffer circuits just yet Check the output of C9 while feeding a low level signal from your signal genera tor into the MICROPHONE input jack Set the panel switch to MIC during this test The scope should display a waveform similar to Fig 11 If you fail to obtain a modulated signal display check the connections to U3 Use your meter to check the dc bias at pins 1 and 4 for presence of 9 6 volts and 5 4 volts respective ly If you obtain different readings resistor connections are incorrect When the output signal from the modulator looks okay power down the Transmitter and restore the link between it and the buffer section Powering up the Transmitter there 46 MODERN ELECTRONICS March 1991 should be no difference in signal at the input and output of the buffer Now plug your antenna into the connector on the Transmitter You should observe no change in the sig nal displayed on your scope If every thing works as described you re ready to go on the air Plug the output cable from a tape deck or CD player into the SIGNAL IN and a 2 to 3 foot length of solid hookup wire strip inch of insula tion from one end first ANTENNA jacks Turn on your transmitter a nearby table or portable AM radio and tape deck or CD player and start a tape or disc playing Set the SELECT switch on the panel to SIGNAL Then carefully tune through the middle of the band on the radio until you hear the program being played on t
204. uitry and B pin functions in the Call Restrictor By placing R Y2 aline sense relay in series with both the red and green insulated tel ephone line conductors the 8031 can intelligently detect whether or not the handset of the telephone instrument is on hook This is accomplished by monitoring pin 2 of C for the pres ence of a ground voltage Figure 3 E shows the circuit de tails for the ac operated power sup ply for the project This is a classic full wave bridge rectifier arrange ment with capacitive filtering and regulation to a tight 5 volts via C8 When the Call Restrictor is in op eration the internal oscillator of JC runs at 11 059200 MHz the frequen cy controlled by crystal XTALI By making use of address lines Ao through Say You Saw It In Modern Electronics A12 ICI can grab needed informa tion anywhere within a range of 8 000 bits hence the use of 6264 15 RAM chip C3 in the section A cir cuitry Although the full 8K memory locations are not used in the Call Re strictor cost of the 6264 RAM chip is so low that no other smaller RAM need be considered Address lines A13 A14 and A15 decoded into chip enabling ground pulses with the aid of 4 Binary codes generated by C at pins 26 27 and 28 are converted into single ground control signals By applying grounding pulses at the appropriate times with a running program any one of eight peripheral chips can be activated simply by ca
205. uld strike a photodetector con nected to an audio amplifier When the fiber is still the only sound from the am plifier will be a gentle rushing noise which is always present Depending on the kind of fiber and the coherence of the laser when the fiber is slightly disturbed the amplifier will emit sounds ranging from thumps and clicks to musical chirps You can use an optical fiber strain de tector to trigger an alarm or counter when the strain exceeds acertain threshold For this purpose a level detector should be connected to the detector amplifier s out put The level detector switches a logic circuit when the amplitude of the signal changes sufficiently The simplest way to accomplish this is to couple the signal from the amplifier into one input of a comparator A voltage divider connected to the comparator s second input can be used to set the trigger level The output of the comparator can go to a one shot if it s necessary to stretch the pulse long enough to trigger an alarm Additional Information A brief but good introduction to strain gage principles is given in Experimental Methods for Engineers by J P Holman McGraw Hill 1984 Manufacturers of strain gages publish applications infor mation that provides valuable informa tion on how to select install and use vari ous kinds of strain gages You can find the names and addresses of strain gage manufacturers in various trade director ies available at libr
206. ut resistors and their failure modes 1 hr 39 95 about capacitors and their failure modes 1 hr 28 39 95 All about inductors and their failure modes Part Includes inductors transformers flybacks pinball coils solenoids 39 95 All about inductors and their failure modes Part ti Includes magnetic clutches relays of ali types other devices 58 min 39 95 Ail about diodes and their failure modes includes rectifiers SCR s Zeners triacs LED s 55 min 39 95 All about transistor failure modes 56 min 39 95 How to solder like a pro with lots of time saving circuit board repair techniques including some of the fastest ways to change IC s you ever saw 1 hr 30 min 39 95 All about electrical contacts connectors connec tions and their failure modes common and uncommon problems symptoms good us 39 95 How to use the oscilloscope to track down digital failures 39 95 How to read schematics and use them for trouble shooting Part i Covers monitors how to find monitor problems with wiring diagrams gives symptoms where to look covers both raster Scan and X Y monitors 56 min 39 95 How to troubleshoot digital integrated circuits includes microprocessors what goes wrong and how to find it how to use the best literature on IC sand where to getit 1hr 45 min

Download Pdf Manuals

Related Search

Related Contents

Manual de Instalação do SAT  ranuradora / roll groover rainureuse / ranhuradura  PT - Australia Telescope National Facility  Manuale tecnico centrale DCA75  2014 09 05 Flyer MDA53 web  2N EntryCom IP Bedienungsanleitung  VL6000 - Velleman  Liste des étudiants du cours  Cipermetrina bobina  

Copyright © All rights reserved. Failed to retrieve file