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!-MR!1The Magazine for people who build electronic gadgets!CONTENTS /INDEXTEST EQUIPMENT PROJECTS9Digital Prototyping System -for bench -topExperimenters32 Ribbon Cable Tester24CUSTOM SOUNDFOR YOUR CARThat Detroit or Tokyo hunk ofiron and plastic you call "transportation" could stand an up -liftin the radio -audio departmentconsidering that the old heap isgoing to pile up more than six digit ABLESWe tell you how to assembleyour own multi -lead cables, including those very expensivepre -assembled ribbon jobs,with the greatest of ease.48SUPER"IfOF28MAKE YOURONUSENSITIVESIMPLEVOLTMETERIIIoscilloscope48 Super Sensitive Simple VoltmeterMini Audio Generator for all sound51systems75 Meg -O- Dapter- checks out insulationresistance83 Scope CalibratorPROJECTS FOR THE FUN OF IT20 Soundbox -80 -add sound to TRS -80games24 Custon Sound for Your Car61 Syndle -the Electronic Candle69 Electronic Slot Machine98 455 -kHz Beat Frequency Oscillator61SYNDLEThe flickering light of a candle hasfascinated man throughout thecenturies. Now you can do thesame without fear of burning yourself or losing the house, by usingan electronic candle that simulatesthe flame's characteristics. To turnit off, you may try to blow it out!42 Single Sweeper One -step -up yourDid you ever think that youcould measure the voltage onthe AGC bus without interrupting the receiver's circuit action.This test circuit can do it andlet you read as low as2 millivolts.79THREE BANDSHORTWAVECONVERTERCOMPUTER PROJECTS28 Make Your Own Computer Cables54 Retrofitting the Sinclair /Timex Computerfor a standard video output-for93 CPP1 Code Practice Processorand stepping -up HamsPROJECTS YOU CAN'T PASS UP-for34 MoCo (Moving Coil) Preamplifieraudio Buffs58 Electronic Flasher for Your Car65 JBL System for Musicians-you build theenclosurePull in the hottest shortwavebands -49 -, 41- and 31meters -plus U.S. timestation WWV with this all -FET,tunable converter.93CPP1CODE -PRACTICEPROCESSORNow you can learn the differencesbetween the dahs and dits, andpick up the required code speed toget your Amateur Radio ticket froma single -chip processor.98455 -kHzBEATFREQUENCYOSCILLATORCrystal -controlled, count -downcircuit helps you tune to thecarrier with accuracy, providingBCB listeners with a new tool.new79 Three -Band Shortwave Converter87 Pro Cabinets for Home-Brew Projects92 Extra - Low -Power Pilot LightDEPARTMENTSEditorial -news on how to Subscribe4 New Products1Coverage Cover8 Advertising Index5our Readers101 Postage -Paid Free Information Cards8 Letters from

NEW PRODUCTSADAPTER, is an RS232 interface adapter forthe Zenith model ZTI personal- informationterminal. The ZTI terminal contains an integral 300 -baud modem for communicatingwith computers over telephone lines. Thisnew interface allows it to function also as anRS232 terminal to communicate with com-puters at the user's site.The interface plugs in between the ZTIkeyboard and power supply, supporting alldata rates available from the ZTI (110 through2400 baud). The retail price of the RS232adapter is 69.00.Magnolia Microsystems, Inc., 2264 15th Ave., West, Seattle,WA 98119.-CIRCLE 820 ON FREE INFORMATION CARDRADAR WARNING,The Bearfinder Quest,provides a four -step relative distance information display, using LED signal- strengthindicators. The first indicator andMAGNOCIRCLE 818 ON FREE INFORMATION CARDaccompanying slow audible beep announcesthe acquisition of the radar signal. Thesecond, third, and fourth indicators each illuminate when a motor vehicle has traversedone-half the remaining distance to the radarsource. As each indicator illuminates, the audible beep becomes faster and faster. Whenthe last indicator illuminates, the sound issteady, warning that the radar source is near.The Bearfinder Quest receives both X- andK -band signals from all types of radar, including moving and hand-held pulse types. It isdesigned for installation on the sunvisor or onthe dash of a motor vehicle. The small, compact case is just 5- inches wide, 13/4- incheshigh, and 4- inches deep, is made of extrudedaluminum, and weighs approximately onepound. It is available only from the factory,and comes with plastic carrying case, velcrosquare for attachment to the dash, visor düp,instructions, and a one -year warranty. Theprice is 239.00.Bearfinder Co., Inc., 324North Dixie Drive, Vandalia, OH 45377.-POWER SUPPLIES, the QPS Series, are inlow -profile design featuring two flushmounting surfaces for easy installatiorr inOEM applications.QPS models have an input of 115 -volts AC 10 %, 47- 400Hz. Voltage /current ratingsare 5 to 24 volts, at 3 amperes. Some features of the QPS series include infinite resolution adjustments, adjustable foldback currentaRadio-Electronics BOOKSTOREBuild Your Own Satellite TV Receiver8 -Ball Satellite TV AntennaBuild Your Own RobotTV Descrambler (January. February 1981)LI Video Entertainment (January 1982)Your Own Computer (October 1981)Radio- Electronics back issues (1983)(January, February 1983 not available)Write in issues desiredRadio-Electronics back issues (1982)(January 1982 not available)Write in issues desired 7.00Radio -Electronics back issues (1981)(March, December 1981 not available) 5.00 12.00Write in issues desired 3.00 2.00 3.00 3.00LISpecial Projects (Winter 1980)Special Projects (Spring 1981)Special Projects #4 (Summer 1982)Special Projects #5 (Winter 1983) 4.00. . 4.00 3.00ri Special 3.00 4.00.Projects #6 (Spring 1983)Radio -Electronics Annual 1983 3.00All About Kits 2.50 2.00 2.00Modern Electrics (Vol. 1. #1 2.25CIRCLE 819 ON FREE INFORMATION CARD 4.95limit, no overshoots on turn on /turn oft orpower failure, and lowest output deratingsHow to Make PC BoardsApril 1908)order any of the items indicated above, check off the onesyou want. Complete the order form below, include your payment, check or money order (DO NOT SEND CASH), and mailto Radio -Electronics, Reprint Department, 200 Park Ave.ToSouth, New York. NY 10003.with temperature. Computer -grade components are used exclusively. Transformersuse the UL- recognized Class B insulallionARTICLEPlease allow 4 -6 weeks forMONTHdelivery.IIWireless & Electrical Cyclopedia(1918) (176 pp)YEARyou need a copy of an article that is in an issue we indicate isunavailable you can order it directly from us. We charge 50 per page. Indicate the issue (month & year), pages and articlePAGESdesired. Include payment in full, plus shipping and handlingcharge.MAILTO@ 50k eachTOTAL PAGESTOTAL PRICERadio -ElectronicsSP -7Reprint Department, 200 Park Ave. South, New York, NY 10003Sales Tax (New York State Residents only) Shipping & Handling (U.S. & Canada only) (Includes FIRST CLASS POSTAGE) 1.00 per itemAll other ( 2.00 per item, sea mail) ( 4.00 per item, air mail) Total Enclosed NameAddressSlateAll models in the series are UL478recognized and are 100% tested before shipment. All carry a 3 -year transferable warranty, and each of the single- output linear powersupply units is priced at 19.95.Deltron,Inc., PO Box 1369 Wissahickon Awe.,NorthWales, PA 19454.-All payments must be in U.S. fundsTotal price of orderCitysystem.ZipSTEREO PROCESSOR, model 6140, takesaudio sub -carrier signals from a satellite receiver and decodes them for use with anordinary home -stereo receiver system. It willalso allow monaural audio sub-carriers to beheardthrough hi -fi speakers for added enjoyment of satellite video programming.Decoding of separate, multiplex, or matrixstereo is accomplished via front -panel pushbutton selectors. Two independent luring

cable programs, video -games, VCR's,Videodiscs, satellite receivers, or home computers at their fingertips.The model VS -6004 also allows the viewerto monitor and edit programs being recordedon a VCR or copied from one VCR to another.High -isolation switching circuits reduce in-drives microcomputers bananas, and manysystems even create their own pollution. Disks and printers often create enough electricalinterference to disrupt an entire program;nearby electronics equipment can beaffected as well.CIRCLE 821 ON FREE INFORMATION CARDcontrols are provided for selecting the sub carrier channel desired in the range of5.5MHz to 8.0MHz. A selectable IF filter allows reception of high -fidelity programming,with low distortion.For tuning favorite stations easily, four independently pre -set positions may beselected using the PROGRAM switch. Popularsub -carrier frequencies have been preprogrammed at the factory on all four of thosepositions. The TUNE position on the switchallows the user to select alternate sub carriers.The model 6140 has a suggested retailChannel Master, Diviprice of 359.00.sion of Avnet, Inc., Ellenville, NY 12428.-VIDEO SWITCH, model VS -6004, providesan inexpensive way to control all TV or Video signal sources connected to a TV set fromone convenient location. By simply flipping aswitch, up to four signal sources may beattached to a TV set and two to a VCR. Viewers will have easy access to off-the -air orCIRCLE 822 ON FREE INFORMATION CARDteraction between signal sources, and prevent interference. The completely passivedevice requires no AC power to operate, andis compact and lightweight. Bandpass isChannels 2 through 83; all connections are75 -ohm type.The model VS -6004 is priced at 41.75.Winegard Company, 3000 Kirkwood Street,PO Box 1007, Burlington IA 52601.-COMPUTER POLLUTION CONTROL, TheMagnum Isolator, is designed to control severe electrical pollution. Electrical pollutionCIRCLE 823 ON FREE INFORMATION CARDThe Magnum Isolator incorporates heavyduty spike /surge suppression and featuresfour individually quad -Pi filtered AC sockets.It will control pollution for an 1875 -watt load;each socket can handle a 1000 -watt load.The Magnum Isolator is priced at 200.95.Electronic Specialists, Inc., 171 So.Main St., PO Box 389, Natick, MA 01760.(More on page 6)-COVER COVERAGEProbably the most exciting phase of preparing a magazine for publication is thegeneration of a suitable cover picture to tellour newsstand magazine readers what wehave to offer them in the issue. And that isexactly what we have done on our cover.However, we did use a few props to dress upthe photographic scene, and I'd like to tellyou about them.Our publisher, Larry Steckler, came upon an unusual tool cabinet (Item A) marketed by Concept 2001, Inc. that gave himvisions of a tidy workbench at home wherethe tools he used most often would alwaysbe in reach. He dug into his pocket andmade the purchase on the spot-that's inpulse buying. When I saw the tool cabinet, Iexperienced impulse larceny! However, thebest I could do was borrow the unit for theAcover shot of this issue of Special Projects.The photo reveals that decorative, washable, plastic tool cabinet with an assortmentof brackets and clips holding all sorts oftools -many of which you'll recognize.Should you care to obtain more informationon the Concept 2001 cabinets and accessories, circle number 872 on the Postage -PaidFree Information Card bound in the back ofthis issue.OK Industries, Inc. was kind enough toloan to us their model SA -3 TemperatureControlled Soldering System (Item G). Itlooks like something that NASA designed,and works as well as their space shuttles, soI decided to use it on this issue's cover. Afingertip control on the SA -3 Hermits accurate and useful temperature regulation of thesoldering tip whereby the experimenter hasthe required heat necessary to solder IC'sonto boards and remove #14 solid copperwire from chassis ground lugs. Now, theneed for more than one soldering iron on thebench, or the dangerous replacement of hotscrew-in soldering tips, has been eliminated. What I like best about the SA -3 is thefeature of reducing the heat on the tip to alow value when the soldering sequence isinterrupted, and then setting the temperature to the desired level for getting back towork quickly. The SA -3 makes sense andOK makes it. Want more information? Thencircle Number 873 on the Postage -Paid FreeInformation Card and mail it today.The other equally attractive items on thecover are projects made by our authors.What is more important: We give you thecomplete construction details so that youcan make your own! Here's the lowdown oneach:-abattery- operated electronicSyndlecandle (Item C) that looks like the realthing. it flickers and dims at a random rate.it is the kind of mood -setter you would addto any room in your home to create anatmosphere. That is the Editor's Choice forthis issue.cleverDigital Prototyping Systempackaging of two probes, clock outputs, andpower supply (Item B) for the test -benchdesigner.Single Sweeper One -an advanced project (Item F) for the digital experimenter andserviceman who still is using yesterday'soscilloscope that does not feature a single sweep blanking circuit.455-kHz BFOmini -project (Item D)that you've talked about but never reallyundertook to assemble. Now you have noexcuse -we give you the complete plans.-a-aMini Audio Generator-At last, apocket -size device (Item E) fortroubleshooting audio systems, providingfrequencies throughout and beyond thelistener's frequency range with output -levelcontrol.That covers the projects found on thecover, but there's so much more in this issuethat I'm sure you'll be involved with projectbuilding until we publish our Fall 1983 issueof Special Projects. Till then, happy build-Julian S. Martining!

NEW PRODUCTSPRINTER, model DMP -100, is a dot -matrixprinter with graphics capability. It prints 50characters per second at 10 characters perinch, and has a bit -image mode to allow print-can be printed on an 8 -inch line, with underline capability. The user can select 10characters per inch (80 columns at 27 linesper minute) or expanded at 5 characters perinch (40 columns). The printer measures516X 16 x 81/4 inches and weighs 83/5 pounds. Itoperates from 120 -volts AC at 60 Hz, uses 15watts, and is U.L. listed. A ribbon cartridge isincluded.ing of fully -addressable, high- densitygraphics. Using an optional screen print program, the model DMP -100 can produce detailed black- and -white graphics printoutssimilar to those on the TRS-80 Color Computer screen display.The model DMP -100 has 80 upper andlower case 5 x 7 dot -matrix characters whichThe model DMP -100 is priced at 399.00. -Tandy Corporation /RadioCIRCLE 824 ON FREE INFORMATION CARDShack, 1800 One Tandy Lane, Fort Worth,TX 76102.MICROCOMPUTER, the Vector -4. incorporates both 8 -bit and 16 -bit microprocessors and presents a choice of several operating systems. It calls on 16 -bit commands tospeed up selected 8 -bit operations. To provide maximum program -developmentflexibility, multiple operating systems areavailable for the Vector -4, including CPA,MS -DOS, and OASIS.The Vector -4 includes a detached key-RadioElecironics.board, conveniently located integral floppydisk drives, and a green-phosphor video display screen that is treated optically to eliminate reflection and glare.With a single -board microcomputer designfor compactness and reliability, the Veda ,-4comes standard with 128K of internal RAM,expandable to 256K. Memory- mapping logicallows the Z -80 to access the entire mainmemory in 64K increments. There are alsothree S -100 card slots for accommodatingSPECIAL REPRINTBUILD A BACKYARD SATF' 11TP T!! RECEIVERSold OutOtt pressSixth printing:rintingPrinting-JustNow AvailapleSeventhReprintsDon't miss out again!Send away today for your 36 -pagebooklet containing a complete reprintof all seven articles in the series onBackyard Satellite TV Receivers byRobert B. Cooper Jr.This all- inclusive report gives you allthe data you need to build your ownBackyard Satellite TV Receiver.TELLS ALL ABOUT domestic satellite communications, with full detailson how you can pull those elusive TVsignals from space.LEGAL REQUIREMENTS, technical specifications, and how you, theRadioElectronicsproaches to making one that willwork for you.Cost.To order your copy:Complete coupon and enclose it withyour check or money order for 7.00,plus 1.00 for postage and handling.We will ship your reprint within 6weeks of receipt of your order. Allothers add 4.00 for postage. NewYork State residents must add 58csales tax.ANTENNA DESIGN. and exactly how you can build a sphericalantenna, while keeping total earthstation cost for the complete systemunder 1,000.THE FRONT END is critical whenyou build your own system. We helpyou explore several different apINSatellite TV Reprints45 East 17th StreetNew York, NY. 10003wantreprintsdling & Postage.I have enclosed add sales tax.Ihome constructor, can meet them.Find out what mechanical and electronics skills you need.RECEIVER CHARACTERISTICS,technical details and specifications,along with examples of actual recsIv, rs built at comparatively low@RECEIVER-SYSTEM hardware, andhow it goes together to bring you direct- from -satellite TV reception inyour own home.SP-7Pisase p,nl(Name) 7.00 each, plus 1. Han- (sneer address)N YState residents musttaro(State)Iz)PICIRCLE 825 ON FREE INFORMATION CARDcommunications interfaces, peripheral controllers, or other specialized input /outputboards. The graphics capability is based on asingle-IC CRT display controller and timesharing of main memory between the CPUand the video -display controller. Thal provides faster access to screen memory, bypermitting it to be anywhere in the 128K mainmemory. High -resolution graphics is provided via a 640 x 312 pixels display.Two versions of the Vector-4 are availlable:the 4/20, with two 51/4-inch, 630K floppy -diskdrives., priced at 4495, and the 4/30, with asingle 630K floppy and a 51/4-inch, 5 megabyte Winchester drive, priced at 5995. Bothversions use Vector's proprietary Dualmodedisk controller, which has automatic error detection and correction circuits. -VectorGraphic, Inc., 500 N. Ventu Park Road,Thousand Oaks, CA 91320.SP

et%nies . VElRádio,.#748784sUMMER198 SYNDLEThe Electronic Candlethat f ickers likea Wax Taperße rragaZt e'or people whobuilb electronic projectsBuild it for TUNINTRODUCINGMAKE PRO CABINETSOUR NEWSUBSCRIPTIONOFFER!for Home -Brew ProjectsBecome aCharter MemberSubscriber!3-Band Shortwave ConverterBectronic Slot MachinePreamplifier for moving coilPhono CartridgeSnundbox -80 for ComputerGame SoundsGet every issue!FTototyping Power SupplyTest Gear 'ProjectsFibbon-Cable TesterSUBSCRIBETODAY!Meg -O- Dapter for OVMMini -Audio GeneratorScope CalibratorSingle Sweeper One BlankerUse the orderJBL Sound Systemfor the musician!form below.Subscribe Today!YOU'RE THE KIND OF READERthat doesn't want to wait, you can orderyour next copy of Special Projects now.Special Projects is crammed full ofelectronic projects that you won't beable to wait to build for yourself. You canexpect top-notch digital projects, fun -toplay electronic games, valuable add -oncomputer projects, BCB and shortwaveIFreceivers, photographic /darkroomgadgets, devices to improve your car'sperformance, test equipment ideas, andmore in every jam -packed issue ofSpecial Projects.TO HELP YOU TO BE SURE thatyou don't miss any future issues ofSpecial Projects- SUBSCRIPTIONSARE NOW AVAILABLE!YOU CAN HAVE THE NEXT FOURISSUES of Special Projects delivereddirectly to your home for only 9.00. Wepay the postage. If you want the nexteight issues, you can even save a dollaroff the newsstand price. Get eight issuesfor 17.00.EVERY ISSUE OF SPECIAL PROJECTS will continue to contain a varietyof construction articles to suit everytaste. In addition, feature articles onelectronics fundamentals, test equipment and tools will round out each issue.Of course, we will continue to providenew product and literature listings tokeep you up to date on the latest developments in electronic technology.GET IN ON THE ACTION! Orderyour next issue of Special Projects today. Use the convenient order couponbelow.-11SpecialProjectsSUBSCRIPTIONDetach and mail today to:SPECIAL PROJECTSSUBSCRIPTION DEPT.200 PARK AVE. SOUTHNEW YORK, N.Y. 10003don't miss any issues. Send me the next four issuesI want to be sureof Special Projects for 9.00: starting with #8. Postage is free in U.S.For Canada add 3.00. Foreign add 7.00.SP-7CASH WITH ORDER ONLYAllow 6-8 weeks for the first issue to arrive.Please printI(Street Address)copies of Special Projects #8Send meat 2.25 plus 1.00 postage and handling for US, Canada and Mexico.U.S. funds only. All other countries add 2.00.(City)IL(Name) want to be sure don't miss any issues and want to save 1.00 too.Send me t

No matter what your requirements in interconnection proaucts, w have just what you are looking for. DIP, Socket, . Los Angeles, Ca 90036 (213) 938 -0166 MIDWEST/Texas/ Arkansas /Okla. Ralph Bergen . RETROFITTING SINCLAIR COMPUTER STANDARD When -- m - much -- can be JBL S EM