CONTROL HOME SECURITY SYSTEM LOW- FREQUENCY RADII CIR REMOTE Popular Electroilics Bulbi A oineSecu rìtv System A commercial-quality system that includes multiple zones, auto -dialer support, adjustable entry and exit delays, and more An Emergency Remote Control For Your Car Disable your car, flash your lights, sound your horn, and more with this easy -to -build .. security accessory G There's a lot of to be had at the bottom r quency spectrun Car Naugatjon es- Nfntfeam -.- .._D _. _- - 3T-7:T _.. lfq:!lltnitdAlílldillltld!l:l.f.11.11udLll : i A look at the first 6 0_ 6: a :44 7 gri3iC: F:-E95 46 system offered by a $3.50 U.S., ROBERT D,A1-111 ESP iSr..f,y 3G-AO # V37 U.S. automaker $3.95 CAN. GERNSBACK C.7;i'_r! www.americanradiohistory.comAmericanRadioHistory.Com Design and Veñfy Cfrcuîts. Fast. CM PPPPP Complement Your Test Bench Here's why Electronics Workbench belongs on your test bench: Wires route themselves. Connections are always perfect. 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INTER TIVE CIRCLE 167 ON FREE INFORMATION CARD www.americanradiohistory.comAmericanRadioHistory.Com OCTOBER 1994 Popular Electronics Vol 11, No 10 A GERNSBACK ¡41' PUBLICATION T C O V E R S T O R Y 31 Build a Home Security System Crime is one of this country's top problems, but this full- featured, commercial -quality security system can help reduce your risk of becoming a crime statistic. It features multiple protection zones, programmable entry and exit delays, autodialer support, panic inputs, and much more -John Taylor, Jr. C O N S T R U C T I O N 47 Build a Multifunction Car Security System Page 31 Flash your lights, sound your horn, or even disable your ignition from up to 100 feet away- Anthony J. Caristi 62 Build a One -Tube AM Receiver Get great high -fidelity performance from this easy -to -build conversation piece -Larry Lisle F E A T U R E S 41 Variable Frequency RF Oscillators Page 47 This introduction to variable- frequency oscillators shows how they work, and how you can use them in your own designs - Joseph J. Carr 55 Ground Zero There's a lot of fun to be had at the low- frequency end of the radio spectrum -Karl T, Thurber, Jr 75 Navigation Systems Go Mainstream Learn about the first car -navigation system to be officially offered by a U.S. car maker -Bill Siuru Page 75 Inc -B Bi- County Boulevard, Farmingdale, NY 11735. Second - POPULAR ELECTRONICS (ISSN 1042 -170 -XI Published monthly by Gernsback Publications, 500 subscription rate U.S. and possessions $21.95, Canada Class postage paid at Farmingdale, NY and at additional mailing offices. One -year, twelve issues, all other countries $29.45. Subscription orders payable in U.S. $28.84 (includes G S.T. Canadian Goods and Services Tax Registration No. R125166280), © 1994 by Gernsback Publications, Inc. All rights funds only, International Postal Money Order or check drown on a U.S. bank. U.S. single copy price $3.50. Inc. Popular Electronics trademark is reserved. Hands -on Electronics and Gizmo trademarks are registered in U.S. and Canada by Gernsback Publications, Publications, Inc. Printed in U.S.A. registered in U.S. and Canada by Electronics Technology Today, Inc. and is licensed to Gernsback Mount Morris, IL 61054-9932 Postmaster: Please send address changes to Popular Electronics, Subscription Dept., P.O. 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Because of possible variances in the quality and condition of materials and workmanship in this magazine. for the safe and proper functioning of reader -built protects based upon or from plans or information published claims any responsibility 1 www.americanradiohistory.comAmericanRadioHistory.Com O C T O B E R 1 9 9 4 Popular Electronics P R O D U C T R E V I E W S Larry Steckler, EHF, CET. editor -in -chief and publisher 18 Hands -On Report EDITORIAL DEPARTMENT Carl Laron, editor OrCad Schematic Design Tools 386+ Robert A. Young, associate editor John Yacono, associate editor 63 Gizmo Teri Scaduto, assistant editor Evelyn Rose, editorial assistant Videonics digital mixer, Sonance in -wall speakers, Brother P- Marc Spiwak, editorial associate Touch PC labeling VCR system, Plus+ Control Tower universal Joseph J. Carr, K4IPV, remote control, and much more contributing editor Marc Ellis, contributing editor Jeffrey K. Holtzman, C O L U M N S contributing editor Don Jensen, contributing editor Marc Saxon, contributing editor 6 Multimedia Watch Multimedia and the MAC -Marc Spiwak PRODUCTION DEPARTMENT Ruby M. Yee, production director Karen S. Brown, 22 Antique Radio production manager A "baby boomer" from Britain -Marc Ellis Kathy Campbell, production assistant Think Tank 24 ART DEPARTMENT Some hobby circuits -John Yacono Andre Duzant, art director Russell C. Truelson, illustrator 77 Computer Bits Fishing for knowledge -Jeff Holtzman Jacqueline P. Cheeseboro, circulation director 82 Circuit Circus Michele Torrillo, POPULAR ELECTRONICS Monitor and detector circuits - Charles D. Rakes bookstore BUSINESS AND EDITORIAL 85 Dx Listening OFFICES Gernsback Publications, DX on the tropical bands Inc. -Don Jensen 500 -B Bi- County Blvd. Farmingdale, NY 11735 1 -516- 293 -3000 87 Ham Radio FAX:1.516- 293 -3115 Using a double -balanced mixer -Joseph J. Carr President: Larry Steckler SUBSCRIPTION ß9 Scanner CUSTOMER SERVICE/ Scene ORDER ENTRY Not -so- private security -Marc Saxon 1- 800 -827 -0383 7:30 AM - 8:30 PM EST D E P R T E T Advertising Sales Offices A M N S listed on page 138 3 Editorial Composition by Mates Graphics Cover by Loewy Design 4 Letters Illustration by John Zeilinski 10 Electronics Library 45 ABC AUDITED 16 New Products 80 Electronics Market Place Since some of the equipment and circuit- ry described in POPULAR ELECTRONICS may relate to or be covered by U S. 95 Popular Electronics Market Center patents, POPULAR ELECTRONICS dis- claims any liability for the infringement of such patents by the making, using, or 138 Advertiser's Index selling of such equipment or circuitry, and suggests that anyone interested in 139 Free Information Card such projects consult a patent attorney. 2 www.americanradiohistory.comAmericanRadioHistory.Com SURVEILLANCE EDITORIAL & SECURITY FM TRANSMITTERS MINIATURE (KITS) 3 -VOLT FM XMTR, up to 300 ft. indoors, 1500 ft. outdoors PHONE XMTR, range to 500 ft., uses phone-line power Sound -Activated XMTR, range to 500 ft. 2 -STAGE XMTR, 9 -Volt, very powerful A MATTER OF SECURITY All above require simple soldering at 2 to 4 places. Broadcast on std FM band. Assemble in less than 5 In poll after poll, when Americans are asked what the number - minutes. Any of the above $29.95** one problem facing our country is, crime ranks at or near the TELE CALL FORWARDER.