^^^^^ ^ ^ JANUARY 1992 tlectnimcs. TECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE BUILD THIS SWEEP/FUNCTION GENERATOR AND FREQUENCY ^"""T1]^ ||H||| Square, trianale ^iM^^^MBBj Jj|H^^^^^^B^^P^ and sine^waves BpE - ^^^^^^^^^^^^^^^^ counter?^ ^■^^^^^^^^^^^1^1^01 S^Hl CABLE TV's MAGIC BULLET Find out how it works^^Hm BUILD A J MONITOR EXERCISER M A convenient S ^QPg troubleshooting ■ tool for computer monitors TURN ANY PHONE INTO A HIGH-QUALITY SPEAKERPHONE Build R-E's Speaker Mate! ANALOG-TO-DIGITAL CONVERSION Experimenting with the IBM PC GERWSBflCK PufluCAIlOfJ FLUKE AND PHILIPS - THE (GLOBAL ALLIANCE IN TEST & MEASUREMENT FLUKI PHIUPS PHILIPS Introducing SCOPEMETEK There^s More Than One Reason to Reach for It* In fact, lliere's every reason to reach fof ScopeMeter Because only ScopeMeter combines the expertise of Fluke and Philips to brir^g you a dual-channel digital scope along with everything youVe come to expect from Fluke digital multimeters. The result: an integrated scope-and^mull^meter that lets you see a waveform and digital meter display at the same time from ttie same input. Or sv/itch between dedicated high-performance Scope and Meter functions with the touch of a key. That makes it faster and easier than ever to capture, store and analyze precisely what you're looking for. At a price that looks good. too. To get your hands on a ScopeMeter, contact your Fluke safes office or your nearest Fiuke distributor For more product information, call 1-800-44-FLUKE. ScopeMeter. Now there's only one to reach for. Simply Easy* Built toTake It. Completely sealed against water, dust and contaminants, • EMI protected and measures up to 600 votts rms. • fluggetJ construction with shock-resislant hofster. ■ Three-year v/arrantv from fluke, Double Dut>^. • 50 MHz digital storage scope and 3000-CDum [figital multimeter in one hesdheld package. • Precision Win Max Record and 40 ns Glitch Capture make it easy to troubleshoot intermittent failures. » Simultaneous wavetDrm and digital disf33ay on a backfit screen you can read across ttie room. * Intuitive front panel layout for simple, straigtitfofward operation • Pop'Ejp menus and five function keys for easy control. » Autosei automatically sets voltage, time and trigger f unctions ' Safety-designed BNC conr\ectors and probes simplify floating measurements. aUW it SEBiiSSCOPEMETEH SEUCTigKliUlDE TrueBMSVoni OiDde Test Time/Divrsion Digital Dflld^or Special Muitimetei Oscllla$£0|te Gliich Capture Wavtlorm &etU0 Wemof) Wavelorm FIUKE IT FLyiCE95 f FlUKEl^ ' -a ana TrTg|>tf Ylei mV/divTn lOQV.div ByNuiiibei o1 Cycles. Events. Tima, U\n Av^rj-gs Record. Resative iw^). dBm. dBV, mi AudJo Watts. Scjie Fiiqytnev. Sfnajthifig;' C^tarlffe Aigri ■ Average V*ha bit Persistence. Win Mji Rgcord Slam jrnj ReuN 8 Wavetanni Sim ind Rtaie to Mulrif^. Inven. Fifltfocinregfit* iy T^iTia Frfquflncy. Smocuhirn)'' a5-?^-C inyrtKt Goes Wherever You Go. i * Runs on rechargeable NiCad Batteries, standard C^ceils or the included line voltage adapter/tjattery ct^arger * Adjustable uit-stanci comes iti fiandy as a hanger too. * Compatible witli a v;ide range of Fluke multimeter accessories. i f FLUKE. 1^ CIRCLE 121 ON FREE INFORMATION CARD January 1992 eIi 35 SWEEPAFUNCTION GENERATOR Generate square, triangle, and sine waves with this inexpensive benchtop instrument MicKaei A. Lashansky 43 SPEAKER MATE Turn any regular telephone into 3 high-quality speakerphonef David Plant 47 MONITOR TESTER Troubleshoot computer monitors without hooking them up to a computer. Garth Price 59 EXPERIMENTING WITH ADC FOR YOUR PC Build a low-cost automatic data-capture system, James J* Barbarello 33 CABLE TV'S INFAMOUS BULLET How a New York cable company zapped srgnaf pirates. Ken Foley 50 WORKING WITH LED^S A close look at a variety of LED circuits. Ray Marston ■ iMJ;^;^y;,i:rB7! 6 VIDEO NEWS What's new in this fast* changing field. David Lachenbruch 22 EQUIPMENT REPORTS McGraw-Hill Science & Technical CD- ROM. 69 HARDWARE HACKER VGA adapter for the Mac LC, computer monitors, and more, Don Lancaster 73 AUDIO UPDATE Reader questions, Larry Klein 75 DRAWING BOARD More on automotive voltage regulators. Robert Grossblatt 84 COMPUTER CONNECTIONS The future of multimedia mayhem. Jeff Hottxman Vol 63 Ho. I 1991 ANNUAL INDEX tffit4t:\ Volume 62 PAGE 63 PAGE 33 96 Advertising and Sales Offices 96 Advertising Index 12 Ask R E 14 Letters 86 Market Center 30 New Lit 24 New Products 63 1991 Annual Index 4 What's News Si 6 10 mZKctronics Even though a dependable hjnc- tion generator and frequency coun- ter are invaluable pieces of test equipment — ones that are a neces* sity on a professional test bench — they're often simply beyond the means of the hobbyist Until now. that is. Our sweep/function gener- ator and f req uency counter produces up to a 2.5-MHz square, triangle, or sme-wave output with a 1- to 20-volt peak-to-peak amplitude^ and it costs just $300 to build. In addition, the instrument features a TTL or CMOS 0.5- to 15-volt peak output, and can be used as a 150 MHz frequency counter. For all the details, turn to page 35. THE FEBRUARY ISSUE GOES ON SALE JANUARY 7. BUILD THIS SCANNER CONVERTER It allows unrestricted coverage of the 800-MHz band. CIRCUIT COOKBOOK Our in-depth survey of LED*s continues with practical chaser and bargraph circuits, SWEEP/FUNCTION GENERATOR AND FREQUENCY COUNTER Part II provides all the construction details. NEW LIFE FOR AM RADIO? Will AMAX receivers breathe new life into the AM band? 4% mnd Mrarkm«nihfp u%cd by ludcrs. RADIC>£L£CTnOlltCS dt^ddinrs mc^y r«spoRiibiFrty for t»l Mii ind praf>«f fa nd i ggw tfl rwd+f-buiEt projccte (used ypoo Qt fwm pUn» or kiformibon pufaiish*d m this mif^At^- 5«fic« %i)tnm of th« «'mi^Hn«M >nd c^xv^^r d»ai^«d m RADtO- ELECTRONICS mxf relite to ot bt eenf*t«^ by U S patents. FtAO«0-EL£CTnON)CS iftftciwfns any It^^Hy kit th« mbifigvfnvnf of tuch p«lertt by the nuking, tmng. or **n*nq of any %ucii •qviprnvrri or c^OiUtry. tnd tugg^fti ihiit anyont m^mtfiQ m *uch ^UftUi consult * patent attorney. RADHD ELf CTRONCS aSSNOtm-THfiSJ - in Ji^r . Publr%Mmor^-tti^fb^Crf7nbxkPubh<^bttn%.\nc ,5O0-BB« County Boulevard, F j inmin9da]« , ^^Y 1 1735 S^O^d-CLa^ ^ FVstAga p*'d M Fftrmi n^d aIc . MV And idd^tGnt,\ m«i!dnublkh«f COrrORlAL DEPAIITMENT Mare SprMrak* «uacia.t9 editor Kim Dynleavy, T«rt Scaduto, as aittant vimt J«Hroy K. Holtzman compuier editor Robert GrosftblaK, cireuiU editor Larry Ktein. audio editor David Lachertbruch contributing uditor Dort L^ncD^tftr contribirtirtg editor Kathy Terenxif edlloriar assistant ART DEPARTMENT Ajidro Diixant, art ditQCtor Injao Le«« itlMStratpr Ru»«aII Tru«t«on, tllustratof PftODUCnOM DEPARTMENT Ruby M* Y««« prDdtictkin director Janice Sex, (Hjitoml prttducbon Kftrefi S. Brawn advertising production Mare«tta Afnoiovo production n % sjista nl CIRCUU^TIDN DEPARTMENT Jacqueline P> CheeselKMti circutation director Wendy Alenko ci rculati on a naly st Theresa Lombardo circulation ^si stent Mkhele TorHlIo^ reprint bookstore Typography by M^ktes GraphiGS Cover pholo by Diversified Photo Seivke^ RadiO'Electfonks is indexed in Applhtt Science S Technology Ind&it and R^AderA Guid6 to Periodical Liter- a fore. Mtcrofilm ik Microfiche edilions are a^irablo. Contact circulation depart- ment far details. Advertising Sales Offices listed on pa^e BB. Radio^OectJDnics Executinie 9nd Adminis^li^ OfBctS V5t6- 293-3000. Stibscnbef Customer Service: t-soo-sed-aGsz, Order Entry for New Subscribers: 1-80CI-999 7im j.j3 QrcuMliurt 159. Don t Wait, This Offer Can't Last! Reg. Price, $259 •Full range -10Hz to 3GHz. • LCD display (daylight visibility). • True state-of-the-art technology with the high speed ASIC. • NiCads & Charger included, • Ultra-high sensitivity. • 4 gate times, ' Extruded metal case. • Compatible with MFJ207. Suggested options TA100S: Telescoping Whip Antenna.,, $ 12. CC30 Vinyl Carry Case $ 14. BL10: LED Backfight..,.- 15. BL28: El Backlight for use in roomlight and low light.., 45. &G2d: Bargraph Signal Level Indicator ...$100. TCXO 30: Precision ±0.2ppm 20 to 40°C temp. compensated time base $100. Universal Handi- Counter"' Model 3000, $375. and Bench Mode! 8030, $579. Both offer frequency, period, ratfo and time interval. 5821 NE 14th Ave. • Ft. Lauderdale, FL 33334 5% Shfp/Handling (Max. $10) U.S. & Canada. 15% outside continental U.S.A. Visa and Master Card accepted. Call for free catalog - Factory Direct Order Line: 1-800-327-5912 FL (305)771-2050 • FAX (305)771 -2052 m CIRCLE ia9 ON FREE INFORMATION CA^O WHAT S NEWS A review of the latest happenings in electronics. Wireless data communication for mobile workers Incorporating Motorola "s RPM400i radio packet modem, a notebook- size, battery-operated computer from IBM (White Plains> NY) will allow users to access and input information to a mainframe computer from re- mote locations. Service tecfinicians. for instance, could use the 9075 PCradio Model 002 to obtain tech* nical information or order emergency parts without leaving the job site. The modem incorporates the smallest and lightest data radio cumently avail- able, according to Motorola. The PCradio operates over the ARDIS network, a partnership of IBM and Motorola that was formed last year to provide nationwide wireless commu- nications to Fortune 1000 compa- nies, and the Mobtdata network in Canada. The unit uses an 80C186 micTOprocessor and operates at ei- ther 5 or 10 MHz. The model 002. whose wireless modem operates at up to 4800 bps. can also be used writh telephone communications networks (at 2400 bpsX PCradio can send or receive fax copies over cellular net- works at up to 9600 bps and over INCORPORATtNG MOTOROLA'S radio packet modem, IBM'S PCradio can pro- vide a wireless link to larger IBM comput- ers via radio or cellular-based communl- caUons— ideal for police officers check- ing license*plate numbers, saies reps requiring immediate information on prod- uct inventories, or service technicians or- dering emergency parts. landlines at 2400 bps. On cellular net- works, with an optional handset. PCradio can be used as a telepfione. Two other PCradio models will also be available: The model 001 is a basic unit for conventtonai telephone com^ muntcations: the model 003 is de- signed for cellular based communica- tions, includes a cellular modem, and can also be used with standard tele* phone networks. As we go to press, FCC approval has just been granted. Highly sensitive moisture sensors Researchers at Sandia National Laboratories (Albuquerque, NM) have fabricated from silicon ex- tremely sensitive moisture sensors capable of making accurate humidity measurement inside IC's. Besides their excellent sensitivity and quick response time, the sensors offer several other advantages, in- cluding consistent performance at temperatures higher than lOO^C. But their primary advantage lies in the fact that because they are made of silicon — the same basic material used to manufacture IC*s — the sen- sors can be made by manufacturing methods that are compatible with the standard techniques used to make ICs. That "complete compatibility" of equipment and procedures holds the promise of the future manufac- ture of so-called "smart sensors ' that combine the sensor and micro* electronic logic elements on the IC chip. That opens the door to such applications as environmental control in buildings by integrating a smart hu- midity sensor within heating, ventila- tion, and air-conditioning CHVAC) systems. The capacitor-type sensors use a material known as oxidized ponDus silicon COPS) as the moisture-ad- sorbing dielectric between the two electrodes in the capacitor. When water vapor contacts the sensor it permeates through the porous vol- ume between the electrodes, caus- ing a net change in the dielectric constant of the porous volume, which is then monitored by measuring the capacitance of the device. Law-enforcement aircraft A light utility aircraft has been spe- cially modified by the British company Pilatus Britten Norman to accommodate state-of-the-art sur- veillance and anti-narcotic detection equipment manufactured by West- inghouse Electronic Systems Group (Baltimore. MDX The modified plane, known as the Mu It i- Sensor Bur- veillance Aircraft, or MSSA, features ijjj ! 1 J THE WEST1NGH0USE Multi-System Sur- veiltance Aircraft (KSSA), a specially modified light ptane fitted with advanced detection and interdiction technologies, is designed for law*erYforcement and anti- narcotic surveillance missions, a unique, bulbous nose that provides enough room for the installation of sensors and avionics systems, in- cluding the radar and infrared imaging system that form the heart of the MSSAs ability to detect and track unusual activity on the ground or in the air. night or day In addition to the radar G000 •5 FfGQ Ranges •variable Rosmve Pom Proto-Board station Special! w Model SC-9000A •3 Wire K Line snput •Function Generator •Triple RDvver Supply •8 USQiC 0 Feature Packed! HiTACHi Oscilloscope Model V>^12 Dual Trace •DC tL . -a^v •6' t*f^ PROBES INCLUDED^ HITACHI Dual Trace Oscilloscope yg|yg| lOO NOW ^598' MOder V-355 PROGtS INCLUOeOf Fordham ASK FOR YOUR FREE CATALOG TOLL Tea Service fit Shipping Charge Schedule Conlinentai US.A, FOR ORDERS AOD FOH ORDERS ADD iO-25 S^50 i $601-750 . SIBOO S60O :S75I1,000 StfiOO sSMOS s?io stooM ?5o saooo 523: 300 Stow iS150MDOO $2^50 $mm i $2.001233 w S3Si)o Whats new in the fast-changing video industry. DAVID LACHENDRUCH • "Flat" tubes. The catch^phase for next years color TV sets will be "flat tubes." Panasonic was the first in this latest flat-tube wave, introduc- ing the "SuperFlat" under its pre- mium Prism brand name. The SuperRat scored a big success in Japan under the name "Gao/* which means "kmg of pictures." The tube has a computer-designed faceplate which isn't really flat but has consider- ably less curvature than a conven- tional tube. In addition, the faceplate is extremely dark, providing more contrast, and new electn^nics supply the power and focus to realize the contrast without a loss of brightness and detail Not to be outdone, most other Jap* anese companies are now preparing their flatter tube versions. Sony will field a "Super Trinitron" in the United States in 1992. and Hitachi. Mit- subishi, and Toshiba are also flatten- ing out their iBceplates in Japan. All of this raises the question: What is **flat'*? In a previous go-round. Toshiba developed the "FST." which originally stood for the ■ flat square lube." However the tube wasn't ei- ther flat or square, so Toshiba changed the phrase to "flatter squar- er tube/' still preserving the acronym "FST" Thomson Consumer Electronics, whose European tube operation has been selling a tube with a computer- designed faceplate — not quite flat, but with a flat appearance — took a poke at Panasonic s Superf fat at a recent trade show with the slogan, "Super Planar world "s first super flat tube — 4 million sold to date." Then along came Zenith, which is develop- ing a truly flat-faced tube, the FTM (for "flat tension mask") tube that uses a piece of plate glass for a face. Zenith filed a complaint with the Bet- ter Business Bureau's National Ad- vertising Division urging it to stop manufacturers from advertising "re- duced curvature" tubes as "flat." But, somehow. "SuperReducedCur- valure" doesn't have that special ring to it. How about going back to "Gao?" • Digital sound for VHS, First there was a longitudinal monophonic audio track on VHS. then longitudinal stereo, then hi-fi helical stereo. Now, finally, digital stereo is here. In Japan, JVC, Panasonic. Mitsubishi, Hitachi, and Sharp have introduced Super VHS recorders with digital audio tracks. The digital sound will be avail- able only with S-VHS because the layout of the standard VHS signal doesn't have enough space for digital audio. The digital*sound recorders* having analog longitudinal and helical tracks as well, are compatible with previous recorders. The digital-audio system can record two channels at 48'kHz sampling frequency. 16 bits, or four channels at 32 kHz. 12 bits. Principal use of the recorders in Ja- pan will be the tape satellite broad- casts that have digital audio. There's no word on whether the digital-sound recorders will be exported. • Public electronics show. The latest advances in TV'Sh VCR s, cam- corders, and home multimedia prod- ucts will be on display to the pubfic as the Consumer Electronics Show (CES) in Chicago opens its doors to actual "consumers" for the first time in its 25-year history. It's expected to attract as many as 100,000 visitors from the Chicago area and beyond. In the past, CES has been for the trade only but this year's show, which will rjn from May 28 through May 31 . will have two public days. May 28 and 29 will be trade-only days, as v/ill the morning of Saturday. May 30, but the show will be open to all visitors from noon Saturday through 6 PM Sunday at the McCormick Convention Cen- ter and the Hilton Hotel. The nominal admission price will be $10, but it's expected that dealers and exhibitors will distribute cut-rate tickets. The shows sponsor is the Electronic In- dustries Association's Consumer Electronics Gn>up (ElA/CEG). • Camcorder format war. The 8mm format was the clear winner in 1991 in the battie of the camcorder formats, with the VHS-C {compact) and full-size VHS models trailing with about equal shares. The ElA tallies sales of "compact" VCR's and full- size VHS. The "compact" category includes both 8mm and VHS-C. For the six months from April through September 1991, compacts outsold full-si2e units by 70% to 30% Cbut for the nine months through September, full-size models represented 33.2% of the total). The ElA doesn't break down compacts between VHS-C and 8mm, but the U.S, Commerce De- parlment keeps track of imports of 8mm as a separate category, without breaking down between VHS and VHS-C model imports. In the latest available figures, for 1 991 's first seven months. 8mm constituted 42% of im* ported camcorders. Applying these figures to the ElA s data, this indt* cates that the ratio in 1991 v^rked out to roughly 40% 8mm and 30% each VHS-C and full-size VHS. But don t count VHS-C out. The VHS-C proponents, led by Ranasonic and JVC, are mounting a major cam- paign stressing compatibility of VHS- C with VHS home VCR decks by means of the VHS adaptor that comes with all VHS-C camcorders — not to mention a forthcoming genera- tion of VCR's that can accept both VHS and VHS-C cassettes without adaptors. The latest trends in camcorders In- clude "digital zoom," an electronic extension of optical zoom to pn^vide as much as 100:1 zoom ratio, at least theoretically At that magnification^ however so much detail is lost that the picture isn't very viewable. Other trends are color LCD viewfinders: in- ternal titles, including pre-selected on-screen messages such as "Birth- day Party." "Wedding," "Our Vaca- tion/' etc.; and remote controls to permit the user to operate the tripod- mounted camcorder while he or she is in the picture. R-E 48HOUR ELENCO & HITACHI PRODUCTS SHIPPING DISCOUNT PRICES 1-800-292-7711 VC-6023 VC-6024 VC'6025 VD-StMS ^ 20MHz. 20MS/S _ SmHl, 20MS/S _ 50MHz, 20MS/S _ lOOMHi, 40MS/5_ 100MHz. 1D0MS/S HiTQcni Hbu :iertes iPortabffl Rvdili-time Digital: Stofago CHcillo^capAS^ _ Si, 695 _ Si .995 _ S2J93 _ £2.995 . S4.495 RSOs frDcti Ktac^i l«a^r« tdO moda. avafa^ing, sav« fnemory, SHioottun^, inttrpo£a£>on, prvtr^ggflfing, cufsor measurfliniftti Th»» scopes ena^jl^ more accurait, sucfi Hjncxvts OS rtardoapy via a ptotter tntftrtua an? wayefomi transfer vta tn« RS-232C interface. En/oy ine comion oi analog an4 tr>9 po«9r fo digtfaJ 25MHz E lenco OscM loscQpe $349 S-1325 • Dua] Trace • ImVSensHivjty • 6* CRT • X-Y Operation fj J • TV Sync ' {2} 1 X, 1 0x Probes mduded SPECIAL BUY V-212 - 20MHr Scope S425 Hitachi Portable Scopes DC to 50MHz, 2-Chonfiel. DC olfiet furtc* tton, A demote magnifief function V*S25 ' CRT ReadouU Cursor Meas S995 V*523 - Deiaye^f Sweep 5975 V*522 ' Basic Model S875 V-422 - 40MHz S775 V-223 - 20MHz delayed sweep $695 ' 20MHz deluxe S625 HITACHI COMPACT SERIES SCOPES Ths serws providts rrifiy n^w tunctjora siJC^ bs CRT FisadcKr^ CufSOf rn«a£ur»frnm {V* 1 08S'i 065A"665A), Fr»- Ousnqr Ctr. |V-10B5), SMWpCiTn* AuUsran^ing. Da^yM 5w«p and TnpoAf Locii u&no * S-meft CRT.Yoli dont t**' E m unns ^ pvtormnnca ana opwabon V-660 - 60MHI. Dual Trace v-eesA ^ 60WHZ. dt. w/cunor _ v^ioeo - 100MH2. Dual Trace V'1065A ' lOOMHi. Dt w/Ojrsor _ V-1085 - 1 0OMHz. QT. w/cursor _ V-11 OOA - 1 0OM Hz. Qt/ad Trace _ V*1150 - 150MH2. Quad Trace . Si. 149 St,345 SI .395 SI .649 SK995 S2J95 S2.595 Elenco 40MHz Dual Trace iGoodIo 4495 '''''' S-1340 High luminartce 6' CRT • 1 mV Sensitivity i Tn;« 10KV Acceleraiion Votiage i 1^ •^^y f • I7ns Rise Time JtJiJ^J • X-Y Operation • Includes (2) lOx Probes M scopes includfi prob«$, schornalics, 6p«ralors manual and 3 year (2 yrs lor Elenco scoporj. Poblbhed by CIE exclusively for our sty dents and alumni. Yours free when you rn|u«st a QE Course Catalog r L f yoy want to le^rn about elecfron- ics, and earn a good income with that knowledge then ClE is your best educationaJ value. crE'5 reputatmn as the worfd reader in home study electronics is based solefy on the success of our graduates. And wo ve earned that reputation with an unconditional commitment to provide our students with the very best electronics training. Just ask any of the T50,000-plus graduates of the Cleveland Institute of Electronics who are wo/krng in high-paying positions with aerospace, computer, medicaf, automotive and com muni- catron firms throughout the world. They ir telJ you success didn't come easy. ..but, it did come.. ..thanks to ClE. And today, a career in etec- tronlcs offers more opportunjtres and greater rewards than ever before. cms COMMITTED TO BEIWG THE BEST...JfSJ ONE AREA. . . . ELECTRON! CS. ClE Isn't another be^everything-to- everybody schooL We teach only one subject and we believe we re the best at what we do. Also, ClE rs accredited by the National Home Study Council* And with more than a 1 ,000 gradu- ates each year, we're the largest home study school specializing exclusrveiy in electromcs* ClE has been training career-minded students Nke yourself for nearly 60 years and weYe the best at our subject ..... ELECTRONICS ... BECAUSE ITS THE ONLY SUBJECT WE TEACH? ClE PROVIDES YOU WITH A LEARNING METHOD SO GOOD, ITS PATENTED, CIE's AutO'prog rammed lessons are a proven learnrng method for burldrng valuable electronics career skifls. Each lesson fs designed to take you step*by- step and princrple-by-prlncrple. And while all ClE fessons are designed for indQpendQnt study, CIE's instructors are personally available to assrst you with just a toll- free calf. The result is pratti€2il training... the kind of experi- ence you can put to work in today's marketplace- LEARN BY DOING.„WrTH STATE-OF- THE-ART FACILITIES AND EQUIPMENT, In 1969, ClE pioneered the first Electronics Labora- tory course and in 1 984, the first Mircoprocessor Laboratory course. Today, no other home study school can match CIE s state-of-the-art equip- ment and training. And aM your laboratory equipment, books, and lessons are included in your tuition. It s all yours to use while you study at home and for on -the -job after graduation. PERSONALIZED TRAINING. „TO MATCH YOUR BACKGROUND. Whife some of our students have a working knowledge of efectronics others are Just starting out. That's why we've developed twelve career courses and an A.A.S. Degree program to choose from. So, even if your not sure which electronics career is best for you, ClE can get you started with WHY CHOOSE ClE FOR YOUR TRAINING? ■ 1 50,000 successful graduates from every country around the world. ■ Only ClE rewards you for fast study. ClE offers an Associate Degree program based on actual study time used. The faster you complete your degree the less your overall tuition. • State-of-the-art laboratory equipment is yours to keep and it comes assembled, ready for hands-on experiments, ■ Approved for educational benefits under the QA. BiU for veterans and other eligible persons, ■ Upon graduation, ClE offers free preparation to pass the Certified Electronics Technician Exams. core lessons applicable to afl areas of electronics- And every ClE course you take earns you credit towards comple- tion of your Associate in Applied Science Degree. So you can work toward your degree in stages or as fast as you wish. In fact, ClE is the only school that actually rewards you for fast study, which can save you thousands of dolfars. SEND TODAY FOR YOUR CIE COURSE CATALOG AND WEXl SEND YOU A FREE 24 PAGE CIE ELECTRONICS SYMBOL HANDBOOK! FINANCIAL AID AVAIL^^BLE TO QUALJFIED INDIVIDUALS. □ YES! I want to get started. Send me my CIE school catalog include ing details about the Associate Degree Program. (For your convenience, CIE will have a representative contact you - there is no obligation.} ae34 N^me: City:. State: Zip: . Age: Phone No, [ . ) . . Check box for G.I. Bulfetin Benefits □ Vereran J Acnve Duty CLEVELAND INSTITUTE OF ELECTRONICS 1778 East 17th SircGt Clevoland^ Ohio 44 11 4 (216) 781-9400 A school of lh«uwnds. A cli)Ss of one Since P934. ASK R E Write to Ask R-E, Radio-Electronics, 500-8 Bi-County Blvd., Farmingdale, NY 11735 fa 6 a: 12 AUDIO LIGHT rd like to build a device that will turn on a tight if the decibel sound level of a band exceeds a preset level at a distance of 75 to 100 feet, rd like the device to be ad- justable between 60 and 120 deci- bels, and when the sound hits the preset level a light will come on and stay on until the sound drops again. Do you have something that can help me? — C. Jones, Broken Arrow, OK Every time I go to a wedding or other large family affair i think dt>out building something like that. It seems that I always wind up sitting right in front of the band s speakers. SeriOLTSly though, this isn't a diffi- cuH thing to design but you can get yourself terribly confused by thinking about things like the distance in feet or the sound levef in decibels. What you're really talking about is building yourself an amp to drive a simple VU meter that can be scaled for really high sound levels. Calibrating it to detect a particular sound level at a particular distance should be just a matter of tweakmg a potentiometer The easiest way to put together a circuit like this is to build it around one of National Semiconductor's LM3915 s. That chip will take an ana- log signal, do all the voltage scaling for you. and give you ten logarithmic outputs that are just what you want for a VU meter While it's a really simple chip to use. I would suggest very strongly that you get a data sheet for it before you start using it. The circuit in Fig. 1 is a good begin- ning for the project you have in mind. It will take four mike inputs, amplify them, and use the outputs to drive an LM3915 set upas a VU meter. One of the nice things about the LM3915 is that simply switching one connection will give you either a bar or dot output. The schematic has the chip arranged for a dot output since you're inter- ested in having a light trigger from only one of the outputs. When you build the circuit, you can hang up to four mikes around the room and use Aim^zo-^^ — If FIG. 1 — TO TURN ON A LIGHT whenever the sound level in a room exceeds a preset levels you can use one of Nalional Semiconductor's LM3915's (see text). the potentiometer shown in the sche- matic to calibrate the LM3915 out- puts any way you want. Even though IVe shown the LED s connected to the chip s outputs, you'll probably v^nt to use one of the outputs to trigger the light you re- ferred to in your letter. 1 have no idea how bright a light you want to use. but it's a safe bet that you won't be abfe to connect the bulb directly to any of the outputs of the LM3915. You just won't be able to get the drive current you need. You can, however, use any of the lAMP RG. 2— TO DRIVE HEAVY current loads with an LM3S1S output you must add a transistor as shown here. LM3915 outputs to drive a transistor as shown in Fig. 2, without having to disconnect the LED. Even a small- signal transistor such as a 2N2222 is chunky enough to light a bright nine- volt bulb as shown. If you want a larger bulb — something like an AC line powered 100-watt bulb — use the transistor's output to power a relay whose contacts can handle the cur- rent required by the bulb. A relay with contacts rated at two amps would certainty be more than adequate, COMMERCIAL LIMITER I've reached my limit as far as television commercials are con- cerned since some of them are so loud Tm afraid they're going to destroy the speaker in my televi- sion set I've been looking for a circuit that would detect a rise in volume and reduce the level go- ing to the speaker I found a cir- cuit called the ^'Commercial Zapper" in an old issue of Radio- Electronics (Feb., 1983), but it blanks out the audio and all I want to do is reduce it Do you have anything that will help solve my problem or at least point me in the right direction?— D, Alford Jr., Li- buse, LA \'m fully aware of the problem you' re talking about . ! don " t know how its possible for people to fall asleep in front of the TV any moiB since every time I try it. the commercials keep viking me up. Nothing is more an- noying than just being on the verge of flaking out during some mindless pap on the tube and being jolted awake by some voice screaming out the virtues of four wheel drive, gourmet dog food or the dirt-eating power of an old de- tergent in a new box. Maybe we should all stick to pubitc television, pledge drives and all. The FCC sets strict limits on the audio level that can be sent over the publicly owned (that includes you and me) airwaves and, believe it or not. the people whose grand mission in life is to say as little as they can in as many words as possible always man- age to stay within the FCC limits. Tve read studies about this and even did some of my own spot measurements to verify it- Tm sorry to report that we can t gel them for a violation of the FCC guidelines. Most of the program audio on the tube has a dynamic range that goes from dead silence to the maximum allowed. The people responsible for the commercials you're complaining about keep the audio level up near the top most of the time and, as far as silence goes, hey, they're paying for thirty seconds and unfortunately they can do anything they want with that time — however obnoxious it might be. The Commercial Zapper" you saw in Radio-Electronics was de- signed to put VCR's in pause during commercials so you could automat- ically eliminate them while you were taping black-and-white movies- The theory behind it was that the color- burst reference signal would be ab- sent during the movie and present only during the commercials. By de- tecting burst, you could tell when a commercial was coming on and out- put a signal that would put your VCR in pause. Most bnDadcasters leave the burst signal active all the time now, even during black-and-white transmis- sions, so the Commercial Zapper. while great back then, wouldn't do a lot for you now. And. since you want to reduce only the level of the sound, there are much better ways to get the job done. Before we start talking about sche- matics and circuits, there s one big thing you should keep in mind. Modi- fying any of the stuff inside your TV, even just the audio circuits, can be an extremely dangerous undertaking. Owning a TV set is kind of like being married — it can give you a lot of plea- sure if you sit back and enjoy it but you can be in for a lot of trouble if you open it up and fool around with the way it works. There are lots of haz- ardous components in a TV and lhey*re operating at voltages that can kill you if you're not careful about what you're doing. If you don't have a good deal of electronic experience under your belt, you should stop reading this right now and switch most of your viewing to public television. Be warn- ed about the hazards in involved. In order to automatically cut the level of the audio from your TV when it reaches a preset tevel you're going to have to modify the audio circuitry in the TV — or at least be able to identify it so you can add to it. You shouldn't do anything to your TV unless you have the paperwork and service man- uals so you can locate and identify the circuitry that deals with the audio. !f you don't have or can't get the paperwork but are still determined to modify it. the safest places to get the audio are either at the volume control or the speaker Unplug the TV from the wall and VERY CAREFULLY dis^ charge the second anode and high* voltage capacitors to avoid a possible shock hazard. Modem TV s use very low leak components and they can hold 3 charge for a long time. The circuit you're looking for is an audio limiter^ — one that will tum the volume down for you whenever the sound gets too loud. Since it's diffi* cult to modify the TVs existing audio circuitry, the best way to do it is to run the audio through a small add-on board. There are lots of limiter circuits but I've been using the limiter circuit shown in Fig. 3 for several years in several applications. All the current that is drawn by the continued on page 82 Home Automation from Heath, the catalog that has it all*.* Enter the world of Home Automation. Remote lighting and appliance controls, Securrt)^ alarms and lighting. Automated thennostats, \1deo monitoring sv^stems. Whole-house securit>^ s>^stenis. They're all yours in the Heath Home Automation Catalog, To receive j^our FREE copy, call today toll-free. 1-80(K44-HEATH (l-aMM44^84) W^- 'ill - 5Sf ■! iij^ip. Heaih Companv Marketing Dept. 020-130 Benton Harbor. Ml 49022 ClRCUe 86 ON FREE INFOFIMATlON CARD LETTERS Write to Letters, Radio-Electronics, 500-8 Bi-County Blvd.. Farmingdale, NY 11735 DIGrTAL SINEWAVE GENERATOR I enjoyed the article "Digital Sine- wave Synthesizer" by Steven D. Swift (Radto*Electronics. Oc- tober 1991). About three years ago, I designed an almost identical circuit for work, I needed a precisely con- trolled sinewave generator that pro- duced srx specific frequencies. Based on my experience, I have some comments for the more ad- vanced and creative hobbyists who are building this project. I have not looked at the contents of the author s EPROM. but Fig. 2'C on page 44 led me to believe that his sme-lookup table contains the zero- cn^ssing values of 80 H at 0'' and 1 80'' on the waveform. Harnnonic distor- tion can be slightly reduced if the ta- ble is offset slightly fronrrthese values (by adding 0.5 degrees to the calcula- tion, for example). I can prove this mathematically^ but the reasoning might be cleaner if you think of the zero crossings as crossover notch distortion. The rate of change of am- plitude of the sinewave should be maximum at the zero crossings. It should not dwell there. The the- oretical limit of the THD is 0.7% (for 256 steps in an 8-b(t EPROM) if this suggestion is followed. The authors circuit shows a dis- crete implementation that should work perfectly Large programmable logic devices, such as the EPt800 series, have architectures ideally suited to the adders and registers that form the heart of the circuit. That is how I implemented my circuit. If only a few output frequencies are re- S quired, a second programmable logic ^ device or an array of gates can be I used to generate the 'A'" inputs to ^ the adders. That reduces the flex- g ibility of the circuit, but also elimi* 1 nates the hassle of looking up binary ^ codes. E If dual outputs are required, two :g circuits that are clocked by the same ^ clock generator can be constructed. Those outputs can be locked to- 14 gether in phase, or varied in phase if an offset generator is placed be- tween the "S" outputs and the sec- ond sine-lookup table EPROM. That then makes possible 26 discrete phases. The author s circuit has no adjust- ment for amplitude or phase. Those can easily be added in one more op- amp stage. When 1 constructed my circuit. I had to back off from 8 bits of resolution at higher frequencies. That caused no problems because higher frequencies were nearer the corner frequency of the low-pass filter, and. therefore, harmonics caused by larger steps were attenuated anyway BRUCE CARTER Port Orange, FL AUDIO SWEEP MARKER GENER- ATOR UPDATE Anyone building my **Audio Sweep/Marker Generator" (Radio- Electronics. February and March 1991) nnight encountera pnDblem that we cannot explain. It concerns 1011. an 8-input nand gale. Two sources of information on the pinout arrange- ment show that there is no internal connection to pin K In the PC layout, pin t is connected to pin 2 to make the foil pattern layout a little simpler That arrangement worked well with my prototype. However, I am inde- bted to Mr Gordon La Grange of Baytown. TX. for pointing out that he had to snip off pin 1 before he could get a proper output fn3m the NAND gate. That output is not shown prop- erty in Fig, 13-e on page 59 in the fvtarch issue. The correct output is properly described in the paragraph almost directly below Fig. \3-k. If you invert the pulses in Fig. 13-e and make them no wider than a single line width, you'll have a correct picture. JOHN WANNAMAKER TRUE TESLA COIL? In the article entitled "Solid-State Tesia Coil ' (Radio-Electronics, September 1991), the circuit is de- scribed as an end-fed Tesia coil I would like to point out that, in actuality, this is not a true Tesia coil in that Tesia dealt with separately tuned circuits (the primary and the second- ary). While it is true that Tesia did use an end -fed resonator in his Colorado Springs "Magnifymg Transmitter." an actual RF-coupled coil was used as the signal generator The basic idea for an end-fed reso- nator was devised by a French inven- tor named Dr. Raul Oudin, who based his work on the experiments of an- other Frenchman, D Arson val. DAr sonvals work centered around what is known as the DArsonval Solenoid, Its purpose was to create, via an in- ductive/capacitive lank circuit, thera- peutic RF currents to treat various iKKiily dysfunctions. Oudin reasoned that high voltages could be produced if one were to attach a second coil to DArsonval "s tank circuit- If one examines Tesia "s patents re- lated to his work in early radio, it be- comes quite evident that the true definition of the Tesia coil must in- elude separate circuits. I would also fike to comment on the size of the secondary coil in the proj- ect. In the case of Tesia s Magnifying Transmitter the extra (or free-reso- nant) coils inductance was actually very low in comparison to the sec- ondary winding that was driving it. The main problem is one of adjusting the frequencies so that the resonant coil runs in the current- fed mode, rather than becoming a simple exten- sion of the driving primary. In the case of the Radio-Electronics project, that would imply that the external secondary winding could behave sim- ply as additional v^ndings of the high- frequency ferrite transformer T2. if any readers wish further clarifica* tion on this. I would suggest the man- uscript entitled "Tesia Coils — An RF Fbwer Processing Tutorial for Engi- neers." by Kenneth & James Comm. Ph.Ds. ffs available from Corum & Associates. 8551 State Route 534, Windsor. OH 44099. BRENT C. TURNER Villa f^rk, CA TUBE AMPLIFIERS REVISITED At this late date. I would like to add my two cents' worth to the ongoing discussion on tube audio annpliffers. I must first admit that I like tube ampli- fiers and have built several of them myself. I believe that correctly designed tube and solid-state amplifiers proba- bty do sound the same, as long as you don't drive either one into clipping. However, to never drive an amplifier into clipping at any point in its circuit requires that suffictent voltage and current be available from each stage, so as to always meet the demands made by the next device. In most tube audio amps, everything up to the final stage is run in Class A1, where the tube is a pure transconductance device, whereas a transistor requires current. Another advantage to tube amps is the fact that they operate at low cur- rents and high voltages. It is much easier to make such a supply smoother and "stiffen" Modern high- end amplifiers and home-built ones made by knowledgeable "audio ama- teurs" use very large values of filter capacitance in their power supplies to provide a high level of resen/e input voltage. Finally, tube amps are simpler and use fewer active devices. The classic Dynaco uses one voltage-ampfifier tube and one phase-inverter triode — both in one envelope as s 7199 — to drive its output tubes; the notorious Carver Silver Seven uses essentially the same basic circuit, A solid-state amplifier comparable to the Dynaco, using only discrete parts, would use two dozen transistors. So. while I must admit that there are some great solid-state amplifiers, I am going to stick with the tube ones. The tubes are still available, the trans- formers can be found, and the elec- trical power to run the heaters doesn't cost much. The added bene- fit to my home-built tube gear is that 1 had a lot of fun building it and spent very little mon^. CHRIS L. DONALDSON Blue Springs. MO COMPUTER CLASHES CONTINUED I really do think that Mr Chengs comments in the April "Letters" col- umn went a bit far — and so did Mr. Holtzman's reply. The entire ex- change brings to mind the old tale about the blind man and the efephant; it really is tough to discern the big picture through all the fog. As one who has programmed extensively for 80X86 PC's. Amigas. and other com- puters, I have more comments than I can fit in a reasonably sized letter, A few wilt have to do. First, on standardization: As Mr Holtzman pointed out, the desirable part about standardization is that it facilitates communication. There are two flip sides. One is that many soft- ware Cas well as hardware) suppliers don't want communication. Suppliers of programs for CAD and music scor- ing are especially notorious — they want you locked tn tight. The second is that standards are often ages out of date — witness the NTSC televi- sion standard — to the point of stifling innovation. The niche machines are a paradox. They owe their existence to the fact that in one important sense they are more standardized than PC's. No two PCs are alike, even in such funda- mentals as memory organization, vid- eo graphics layout, and interrupt organization. As we all know, that causes no end of problems. Within the CPU itself, the instruction set is an unstandardized chaos, having on the order of a thousand individual quirks. Even the largest, best-cap- italized organizations have been able to cope with that, so that compiled code tends to be a wretchedly sub- optimal joke. The lessons of the old mainframes have yet to be learned. The upshot is that things that aren't done often enough to support multi- biltion-doliar software companies are often best done on niche machines, especially if speed, large memory, or a GUI is desired, or interrupts are needed. Sure, a Lotus or a Microsoft can handle the problems caused by dozens of graphics drivers, dozens of extended memory drivers, more than 500 printer drivers, dozens of slightly different serfa! and parallel ports, hun- dreds of quirky BIOS variants, and hundreds or maybe thousands of hard-disk variants. The person who writes a specialized program for filter analysis and sells a few hundred cop- ies probably can't make it multi-com- patible, except by resorting to lowest-common-denominator user Earn Your B.S. 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Even then, its never fBally certain that the prt>gram that njns on my PC will run on the PC next door— and getting it to print properly on the system next door is well nigh out of the question. So. what will become of those 60 million PC s, plus the Macs, Amigas. Ataris. and so on? Its sad, but hu- manity has been down this mad be- fOfB. and we Find that horse carts, though they were once as abundant proporttonally simply aren't permit- ted on the freeway Those computers aren't going to make it either though some, notably the DOS PC, may well hang on for a long while as windows in some POSIX^OS/2-Windows-DOS' Sparc-Mac-PC-Amtga machine of the future, CAfter all, if it were worth the trouble, it wouldn't be all that hard to Simulate an Apple or Commodore 64 of seven years ago on a 486 PC, high-end Mac, or hrgh-end Amiga — fesfer than real time!) And that raises what should be the hottest issue of all, something far more important than ranting and rav- ing over doomed PC's versus doomed Macs versus doomed Amigas. The issue is our own data, which we must somehow get out of that DOS window and onto that ma- chine of the future — to say nothing of moving it from one application to an- other or to a supercomputer. We have allowed much of our data, en- tered laboriously and at tremendous expense, to become embodied in files that are formatted in obtuse, se- cret, and unstandardized ways. It is high time that the software manufacturers who practice this are forced to change. They are in effect thieves who have stolen from us what is rightfully our property. It is lime to insist that all software that we buy have the capability to disgorge our data in full, including such things as the coordinates of graphical objects, in an open, published-data-inter- change format. As a symbolic dis- couragement to theft and extortion by software manufacturers, and to al- low third parties to assist m retrieving the stolen property without fear of litigation, it is time to amend the copyright law to explicitly permit re- verse engineering in any program that stores output but won't provide it in an open format, irrespective of any and all language to the contrary in the licensing "agreement. ' We have been down this road be- fore. Compiler suppliers once swore that royalty-free function libraries would end the world. Much the same was said of ANSI- standard C. and of spreadsheet DIF files, and so on. Od- dly enough, the world is still here. So to any manufacturer who feels this proposal is unreasonable. I say this: Maybe your problem rs that your are making money by holding your cus- tomers up for ransom, rather than by providing a good product. If so, the sooner you are out of business, the better— preferably on terms that are as punitive as possible to you, your investors, and your bankers. You are not indispensable, regardless of who you think you are or how big you are. There are hungry hordes waiting in the wings to replace you. PAUL SCHICK Madison, \M R-E LEARN Chan/ Mainiain/ Rbwr CAMCORDERS HUGE EXF'ANDING MARKET! VViitk hoifi >iNii hiM»iHi' |kir1-1iiiK> fjr lull liiiu/! Xn jHHif i-\fK-iit-iM m'^tkHl AviT,ii;f nm Immk tit ai^ililv ^ of the main logic board, install the power supply iim\ 1 .2 meg high-density floppy disk drive, then interface your high-resolution moniton What's more, you now go on to install and test a powerfiil 40 meg IDE hard disk drive — today's most-wanted computer periph- era! — inciuded in your course to DIAGNOSTIC HARDWARE AND SOFTWARE It A.<:.H.k plug in diagnostic tanJ :inU Quick! tch mtnu il riven sf if I ware, boih fnmi rtjrhi-Xi j^iVL' you hinds^n t xpL ricncc with today's pn>jcs:s tonal diagnostic imils DISCOVERY LAS t ;ijniptt-ti' hrt-4t3bH:i;ird]ng sysiem lets ift'sijin .11 id iiifidify- Lin II it >, diJgiioSL- mh} ncjmir &uits LESSONS t-kMr, ilhivtnied texts huitd ) uur undcfst^Lndin^ 1)1' LonipuEL-r7> step by step MONITOR Eli^h' resolution, nonglarep I i" HI. nKinothronic jiuinittir with tilt and »wlvi't DIGITAL LOGIC PROBE Simpliftcs analjp-zLng digiLaJ circuit optratkm DIGITAL MULTIMETER rruft-s^ional test vn^imm^n tot quick and asy ntcasur^mcms SOFTWARE f BAfil<:, and (Xipuliir Mit r<:fS)>rt Works iipplicatioiiK w if [wan- dramatically tncreiise your com- puter's data storage capacity while giving you lightning- quick data access. But ihat*s ni)t all! Professional diagnostic hardware and software makes troubleshooting fast and accurate Your NRI training now includes a remarkable diagnostic pack- age that allow^s you to quickly locale and correct defects in IBxVI XT, AT 80286/803B6, and shows you how and service likeNRI! IEW[ 40 MEG HARD )ISK DRIVE! \iu tnMuLl this Hi iiK'^ IDU tarti disk ilrivx- iiiunnill) , \m ;rcatcr ttata storage t apaLily jid dau access iipccd NEW! 3B6SJE.20 MHz MINITOWER COMPUTER! Fcsuirci 32 bit i*l).iHfi^v t I'E L 1 mt'g RAM, tV4K HtJM, i > mt^ [iigh^«i>iT>" rluppy disk drive NRI givc5 you the confidence and the know-how to step into a full-time, oioncy-muking curccr as an industr}^ technician, even start a computer service business of your own! No experience necessary... NRI builds it in With NRI, \'ou leam ai your own pace 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. And all througliout your tndning, you have the full support of your personal NRI instructor and the NRI technical staff, always ready to answer your questions and give you help when- ever you need it, FREE catalog tells more. Send today! Send today for NRJ's big, free catalog that describes every^ aspect of NRI's innovative computer training, as well as hands-on training in 'IT/vidco/audio ser\1cing, telecommunications, indtistriai electron- ics, and other high-growth, higlvteeh career fields. If the coupon is missing, write to NRI School of Electronics, McGraw-Hill Continuing Hducation Center, 4401 Connecticut Avenue, NW, Washington, DC 20008. IIIM ii a regisLtTcd Iradciiuik of lntcTn;itk>iul Bu.vinc.'w Mic tilac) tkjfp. QuickTctrh and K..A.C.E.R. are rc^mtl iratlcmarius of tJUrA-X, Inc. West Ccast is a mrrnbtT of t\K Syniaj( <^roiip. compatible computers. You'll use your Ultra-X Quickl ech diagnostic softvt^arc to test I lie system RAM and such peripheral adapters as panillel printer ports, serial communications ports, video adapters, and floppy and hard disk dnves. You 11 go on to use your (tAXLHJt diagnostic card, also from Ultra-X, to identify indi%HduaI defective RAy\ chips, locate interfacing problems, and pinpoint defective support chips. This ingenious diagnostic package is just one more way School of Electronics McGniw-Hill Coit Uniting lidicaUon Center 4401 C □ Basic Electronic* For career courses approved under (il JJIII Q cheek ftir tlet^iUs O Computer Programming □ Securit>- Electronics □ Electronic Music TecJincilogy □ Desktop Puhlbhing □ PC Software EnRtnecdnK Using C Name (Picaiic prinO Ape Address CLty/Stotc/7ip Accrejdited Member, MatEonaf Home Study Council 3Q12 EQUIPMENT REPORTS McGraw-Hill CD-ROM Science and Technical Reference Set c i o _© w a ■u EE 22 Everything you ever wanted to knovi/ on a disc. CIRCLE 10 ON FREE INFORMATION CARD What would you say if we told you that you could have easy access to all of the McGraw-Hill Concise Encyclopedia of Science and Technology and the McGraw Hill Dictionary of Scientific and Technical Terms without having to giME up any room on your alrBady crowded bookshelf of reference and data books? Thanks to the CD-ROM format, all of that fits on a disc that looks just like a standard audio CD, The Concise Encyclopedia, which contains sonne 7700 articles and 1700 photos and line drawings, is a condensed version of McGraw-Hiirs 20-volume encyclopedia. It has been one of our favorite desk references for the past severa! years because of its broad coverage of more than 75 major science and engineering disci- plines. Unfortunately the book is a bit unwieldy — it has more than 2000 pages, is ZV2 inches thick, and weighs several pounds. The Diction- ary of Scientific and Technicaf Terms is another impressive reference, with 117.000 terms and definitions. Unlike a book, you need the right computer equipment to read a CD- ROM, First, of course, you need a CD-ROM drive with the Microsoft CD-ROM extensions that allow DOS to access it. (The extensions are sup- plied when you purchase a drive,) You also need an IBM AT or better PC with 1 megabyte of expanded memo- ry compatible with the UM CLotus- Intel-MicnDsoft) specification, and a minimum of 1 megabyte of free space on your hard disk drive. If you want to view the graphics, you'll need a VGA graphics card and monitor If you want to output text to a printer, you'll need a LaserJet or compatible. A mouse is supported, but not required. As long as you have enough space on your hard disk, you'll run into little problem installing the software. A setup program on the CD-ROM cop- ies files onto your hard disk, and modifies your CONFIG.SYS and AUTOEXEC.BAT files. Using the database Once the installation ts finished, you're ready to jump into the database/The retrieval software. Dis- cover is your interface to the refer- ence set There are several ways to get to the information you want: graphic access, alphabetical access, link-phrases/terms, and complete text search. Graphic access is the way to go if you don*t know the precise term or phrase you want lo find information on. A color graphic, "Mirror of the Cosmos" appears on the screen, re* fleeting the major disciplines of the encyclopedia. You could click on "En- gineering/' for example, and then be presented with another graphic — this time it s a laboratory bench with note- books and textbooks scattered around and on shelves, with titles such as "Electrical Power" "Tele* communications," "Physical Elec- tronics," and "Electronic Circuits/' When you click on one of those, you're brought to another non -graph- ic menu, which allows you to further narrow your choice. For alphabetic access, you display the table of contents. But since all 7700 articles can't fit on the screen, you have to "expand" it alphabetically to get to the choice you want. Accessing a "link phrase" is. how- ever the best way to find information if you know what you're looking for It s the fastest method, because it works by finding the hypertext links in each article and illustration. The provision of hypertext ca- pabilities is an important feature of the reference set. The links allow you to jump for one article to another as you pass terms of interest. Any major links are indicated on the screen in color You can navigate the data in the reference via the 'links'' that tie the data together. So if you were reading an article on electronic listening de- vices, you might see links to "Ampli- fiers ' or "Radio Transmitter." It is also possible to do a word search on the entire database, but that inefficient searching takes an awful long time. We found the data base to be r^fa- trvely easy to use. although we would have preferred to have an on-disc tu- torial. After all, there's certainly enough room on the disc for a multi* megabyte tutorial. We think that the McGraw-Hill CD^ ROM Science and Technical Refer ence Set is a very strong product. Before you buy however, consider that the paper versions are available for a total of just over $200, The CD- ROM, which has much lower prcsduc- tion costs, selfs for $495. R*E CABLE TV CONVERTERS AND DE- SCRAMBLERS SB'3 $79.00 TRI-BI $95.00 MLD-$7g.OO M35B S69,00 DR2-DIC SI 49,00. Spectal combos available. We ship COD. Quantity discounls. Call lof pricing on other producis- Dealers wanied. FREE CATA- LOG, We stand behind our products where others fail. One year warranty ACE PROD- UCTS. P.O. Bon 5S2. Saco, ME 04072 T (800> 234-0726. CIRCLE 75 ON FREE INFORMATION CARD ! HWTOGETANrTMNC COMPUTER CRACKING. INFORMATION TRACKING, culling edge audio video sur- veillance, electronic traihrig, night vision, sur- veillance photography, mlelligence kits, cellular, pager, fax interception, recorders, scrambling and sources. ALL NEW — BOOK II HOW TO GET ANYTHING ON ANY- BODY— Lee Lapin. "Really scary stuff"— Charles Jaco, CNN. $38.50. ISECO, 2228 El Camino, No. 349-R, San Mateo, CA 94103. CIRCI^ t94 ON FREE INFORMATION CARD APPLIANCE REPAIR HANDBOOKS— 13 volumes by service experts; easy-^to- understand diagrams, illustfations. For major appliances (air conditioners, refrigerators, washers, dryers, microwaves, elc.)* alec, housewares, pefsor»al-care appliances. Basics o^ solid state, setting up shop, te^t instruments. S2.S5 to S5,90 each. Free brochure. APPLIANCE SERVICE. PO Box 799. Lombard, IL S0148. t-{312) 932-9550. CIRCLE 84 ON FREE INFORMATION CARD THE MODEL WTT-20 IS ONLY THE SIZE OF A DIME, yet transmits both sides of a tele- ptione conversation to any FM radio with crystal clarity Telephone line powered * never needs a battery f Up to mile range. Adjusta- ble from 70-130 MHZ- Complete kit $29.95 * 51,50 S * H, Free Shipping on 2 or more! COO add S4. Call or send VISA. MC. MO. DECD INDUSTRIES. Box 607, Bedford Hills, NY 10507. (914) 232-3870. CIRCLE 127 ON FREE INFORMATFON CARD FUNCTION GENERATORS WITH INTEL- UGENT 100MHz FREQUENCY COUNTER. Sne, square, triangle, ramp. DC d Sync, TTL outputs. Seven frequency ranges: 2 Hz (o 6MH2 (FG-506). 2H2 to 13MHz (FG-513^. In- telligent 100MHz frequency counter with period mode. Continuous, trigger, gate, clock, sweep and e)cternal frequency modes. Un^ Log sweep. Adjustable duty cycfe/symmetry. Voltage controlled frequency functions. TCXO with ippm/yr. aging rate {optional). FG-506 S695.aO; FG-513 S1295.00. Calh, 300-664-9838. AMERICAN RELIANCE INC., 9952 Baldwin PL, El Monte, CA. 91731, CIRCLE 17G ON FREE tNFORMATION CARD CREATE INTELLIGENT PROJECTS WITH THE VERSATILE 28 PROGRAMMABLE MICROCOMPUTER. This powerful comput- er was designed for flexibility and can be used for various electronic projects, 10 )ntensi\'e. Up to 20 MHz operation. Download programs or njn EPflOM code. Special hardware fea- tures included. Prices from $125.00. Battery^ backed RAM, X-assembler. and other opt ions available. CALL FOR FREE BROCHURE. MJS DESIGNS, INC., 1436 W. Broadway Rd., Suite B165. Tempe, AZ 65262. (602) 966-36ia CIRCLE 179 ON FREE INFORMATION CARD CALL NOW AND RESERVE YOUR SPACE • 6 rate S940,0O per each rnsertion. • Fast reader service cycfe. • Short lead time (or the placement of ads, • We typeset and layout the ad at no addilionaf charge. Call 516-293-3000 to reserve space. Ask for Arhne Fishman. Limited number of pages available. Mail materials to: mini'ADS, RADIO-ELECTRONICS. 500- B Bi^County Blvd.. Farmingdale, NY 11735, FAX: 516-293-3315 II II [ 5 MINUTE ASSEMBLYI MONEYBACK GUARANTEE! Attach the VT-75 chip to any 3V'12V battery and you have the most power- ful miniature transmitter you can buy anywhere. Tiny Law Enforcement grade de- vice allows you to hear every sound — even footsteps— over 1 mile away on any FM radio or wideband scanner. 80-130MH2. lOOmW output 1 VT-75 microtransmitier complete $49,95 4-51.50 S & H, Visa, MC. MO. COD'S add $4.00. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. I^SOO-759-5553, CIRCL£ 127 OH FREE INFORMATION CARD FREE CATALOG! ELECTRONIC TOOLS & TEST EQUIPMENT— Jensen's new Master Catalog, available free, presents major brand name electronics tools, tool kits^ and test in- struments, plus unique, hard-lo-find products for assembly and repair and custom field ser- vice kits avaitable only from Jensen. All fully described and illustrated. Enjoy free technical support and rapid, post-paid delivery any- where in the Continenta! USA. JENSEN TOOLS. INC.. 7815 S, 46lh St., Phoeniic, A2 85044. Phone: 602-960-6231; FAX 1*800^36&-9e62. CJRCLE 115 ON FREE INFORMATION CARD NEW PRODUCTS Use the Free Information Card for more details on these products. Oi § -? 8 C 2 I lij g or 24 HUlIIIVMniOri COUNTER. Especially well-suited for the communications indus- try. B&K Precision 's t856 multifunction counter can be used to make highly accurate and repeatable measurements of radio transmitter frequency right up to the microwave range. It exceeds the require- ments for adjusting trans- mitter frequency to FCC standards* as required for radio stations or land mobile, radio telephone fe- ceivers. Because the 1856 extends to 1 .3 GHz. it even covers cellular channels. The counter has a 5-Hz to 1.3-GHz bandwidth and a TCXO (temperature- compensated crystal os- cillator) timebase with 0,5- ppm stability at 3 and 1-ppm stability from 0 to 50°C. The moden856s functions include frequen- cy, period, period average, and totalize. The period- measurement function, used for very low-frequen- cy measurements, makes CIRCLE 16 ON FREE INFORMATION CARD it easy to measure tone-en* coding functions used in may types of communica- tions systems. In the total- ize mode, useful in count* ing the number of opera- tions performed by produc- tion machines or in quality- control tests, pulses from 5 Hz to 10 MHz are counted up to 99.999.999. Reset and hold can be performed using a switch, or using a remote start/stop input. The compact model 1856 measures 2.5x9,4 X 7.5 inches and weighs 3.3 pounds. It's large, high-intensity. 8-digit LED readout provides kHz/pis, MHz/ms. gate, and overflow indicators. A detachable power cord, a schematic, parts list, spare fuses, and an instruction manual are included. Op- tional accessories include an antenna for conve- niently checking transmit- ter frequency and a 10:1/ direct probe. The model 1856 multi- furiction counter has a sug- gested list price of $495. — B&K Precision. 6470 WestCorlland Street, Chi- cago. IL 60635; Phone: 312-889-1448. ACCELERATION SENSOR. According to Analog De- vices, their 4DXL'50 is the industry's first surface mi- cromachined acceleration sensor Caccelerometer) and the only one to offer complete signal-con- ditioning and self-test cir- cuitry on-chip. Designed primarily for automotive ap- plications such as collision detection, active suspen- sion« and anti-skid braking systems » the device mea- sures acceleration in a sin- gle plane of sensitivity over the ± 50-g range to an ac- curacy of 5%. Self-test cir- cuitry is activated by a digital command and guar- antees operation of both the sensor and associated signal conditionmg to stated specifications. That CIRCLE t7 ON FREE INFORMATION CARD is a vita! feature in applica- tions such as air-bag sys- tems. The ADXL50 mea- sures only 500p,m x 625M.m, much smaller than other types of micro- machined sensors. Unlike other accelerometers that monitor the resistance change of stressed piezoresistors to detect acceleration, the ADXL-50 measures the changes in capacitance, and is there- fore insensitive to tempera- tune changes. The sensor operates in a force/balance mode. Volt- age is applied to the sen- sor, which produces a force exactly opposite to that caused under acceleration. The sensor therefore re- mains at rest at all times, and the nonlinear mechan- ical properties of the silicon structure can be effectively ignored. Signal-con- ditioning circuitry provides excitation signals for the sensor, then amplifies and linearizes the analog out- put signal to 0.25 to 4.74 volts. The AD XL 50 acceler- ometer costs $23.00 (100 s) and $5.00 in auto- motive OEM quantities. — Analog Devices, Liter- ature Center. 70 Shawmut Road. Canton, MA 02021. DMM ACCESSORIES, Anew ime of modular test ac- cessones from Fiefdpiece is designed to solve such on-site servicing problems as not having the right test lead for the job, alligator clips that pop off of test points, and too-short probe tips. The solution is simple but innovative: All the ac- cessory connectors, in- cluding the connection between the probe tip and the probe handle, are stan- dard banana plugs orjacks. A female banana jack, buift into the "handle" of the de- luxe test lead, fits a sleeved male banana plug. The line includes a variety of probe tips, alligator clips with pig- tails, and a current clamp head, all of which plug onto the end of the deluxe test lead. One test lead end can be plugged into another to double the length of the test lead; with the addition of an alligator clip, it's pos- sible to build an 3-foot CIRCLE 18 ON FREE INFORMATION CARD ground lead that is unlikely to come apart. The ac- cessory kit, model ADKIO includes a pair (red and black) of each of the follow- ing: 42-inch test leads, small and large alligator clips, and short VMncU) and long C3-inch) probe tips, packed in a plastic box. The box has room for the model ACH current clamp bead, which can be used with Fieldpiece "Stick"- style DMM's as well as any multimeter with ImVDC resolution (most meters). The small-head cfamp fits into tight spaces and mea- sures current up to 300 amps. Also available is the ALCt leather case, which holds a DMM and ac- cessories. It has a belt loop on the back and leather loops on the front hold two extra probe tips or the ACH current clamp head. The leather case can accom- modate a "Stick," Fluke 70 Series (without the boot), or Beckman 220/150 Se- ries (without the tilt stand) multimeter. It is available with the accessories and current clamp head as model ALCK8. The ADKIO accessory kit. ACH current clamp head, ALC1 leather case, and ALC8 leather case with accessories and current clamp head cost $26.95, $24.95. $24.95, and $59.95. respectively.^ — Fieldpiece Instru* ments, Inc., 8322B Ar tesia Blvd., Buena Park, CA 90621: Phone: 714-9921239: Fax: 714-992-1239, UV-LIGHT-8L0CKING EPROM LABEL. When used on EPROM packages, a UVopaque write-on label I — _ ^ EPRCM's are safe f ro« uv with BP labels IBIbLLLLLL CIRCLE 19 ON FREE INFORMATION CARD from DATAKiCat# EP^D gives added assurance that the burned program will not be accidentally erased by stray light from fluorescent lannps or other ultra-violet sources. The la- bel consists of a white po(y- urethane layer for writing, a black opaque-vinyl layer and a layer of pressure- sensitive adhesive. The flexible film construction conforms to EPROM pack- ages having raised win- dows. The label can be removed wrthout leaving an adhesive residue on the EPROM package. Sized to fit on top of a 24-pin wide DIP the t.1 X 0.46-inch la- bel will accommodate three lines of standard type. It can be written on with a typewriter, bali-point pen. soft pencil or any platten feed computer printer. Cat# EP-1, containing Train at HOME to be an Eledrnnics Technician \ M the demand for cixnputef^ and mttmproct^sorv in bu5irtcs^< manuMcruring and communic.iiium continue!^ lo grow, doe^ the net>d for quiilifit'd technicijni, U'l not unit^Util for OT^pffiencfd techniCFtins to iMm fmm S '10,000 to more thiin S 4 0.000 J year. ' Now ihrouf^h Puopfcs Collcf;?** of IndefKMidont SiudlL^s you cin triiin for lUis exciling iivki svilhuul irvterru|?ting your joi) or home life. • Indu^trtdl Elect ronic^H & Micfoproce>^r Technology • Communkattons El^ronio with Mlcrc^ processor Technology • Compute? Sefvicitig & Electionic* Teehmitogy • Specialised A^^ociate Oegiee In Elearooic^ Technolofcv Pro^essioml Equipment h tncbded J Depending on the program you §elet:t, you'll peftecT youi skills using this advanced equipment, included in thi> price of tuition: • IBN'V'Compatibl^ Personal Compulor ■ Digital Multimeter • Digital Logic Probe • Elenco Oscilloscope • Portable Cellular Tefephone Enbance Yotir Trainlrig Peoples College introdtice? ^^nn- irjsnmii rtrsts to make youT leamirrg e^-peiience mont* completer • Accelerated Learning S^'siem — a scientifically prm^ study- system that help^ yov (earn fa^er diHi easi«?T than ever before, •Video Tutor Training Tape* — give you a pefmanenl. vi^uaJ record of infonnati^-e lecTUfes artd cIoscHip demonstrations. • Experience labs — protessiooally designecf ex peri men IS that give you handsHKi "bench" experience. • Industry Cerittlc-ation Training Cuitk'' — pmviiJt'd with tour of our programs. PretKires you iot examinations you may take for your professional license or certification. aymeni PUi Tcjhelp VI I'M •fW] > [art I'd on ycjur c^lucation. Peoples Co1k»H,£' Ims rtitiLKL'tl luidtin rates and o^fer^ low monihty ihiymcni pLins with no finance fees. So Council YES! ! M outd like 1o know more about your * Ir^tnjrtg programs. Send a catalog to: * I I I Name _ Addreu City _ State Zip Phone # Peoples College ; I U I N J P t N I N r 5 T U D I E S I 231 Academy Drive « P.O. Box 42t7&8 | Ki»!mmee, FL 34742-1 76fl , . 0 1, rwpi^ Cf^Hie R0192 , CmCLE 190 ON FREE INFORMATION CARD 147 UVopaque EPROM la- bels on three sheets, costs $4 00 — DATAK Cor- poration. 55 Freeport Blvd.. #23. Sparks. NV 89431 : Phone: 702-359-7474; Fax: 702-359-7494. SERIAL LINE MONITOR/ PROTOCOL ANALYZER SOFTWARE. DataScope Version 2.0 transforms a PC into a passive or active RS-232 data and signal- line monitor that can elimi- nate guesswork while deal- ing with serial transmis- sions. The upgraded ver- sion of Paladm SoftvimrBS program is still capable of collecting 8 megabytes of data and signal information with microsecond time* stamp resolution, but has been enhanced with tiled concurrent window dis- plays and a pull-down menu interface. Up to four unique CIRCLE 20 ON FRIf INFORMATION CARD and simultaneous displays can be active at the same time, pruviding passive, in- teractive, and historic monitoring in any user-se- lected combination. Dis- play tiles can be combined to create larger windows, and on of four presentation filters (mixed, alternating, C0M1, or COM2) can be applied to every window. DataScope can opefBte at all possible rates up to 1 1 5.200 baud, while match- ing user-specified trigger strings against incoming data. It offers full archive- parameter control com- bined with pre-, center-, and post^rigger position- ing. Character translation sets can be replaced or al- tered by the user to modify the translation strings and/ or attributes for each source separately. Version 2,0 runs on all IBM-PC- compatible machines with MS-DOS 2,1 or above. 256K of available RAM. and at least one serial port. DataScope Version 2,0. with connector shells, ca- bles, and a comprehensive manual, costs S249.— Paladin Software. Inc.. 3945 Kenosha Ave- nue. San Diego. CA92117: Phone: 619-490-0368. CEBUS-NETWORK DE- VELOPMENT PROOUCTS, An mtegrated circuit, a modem subsystem, and an evaluation system from In teflon Corporation will enable manufacturers and application developers to implement carrier sense/ multiple access CCSMA) networks over standard AC electrical wiring. The pnDducis are based on In- tellon's patented ''Spread Spectrum Carrier"* tech- nology, which is being con- sidered by the Electronic Industries Association as the power-line signalling standard for its Consumer Electronics Bus CCEBusX The CEBus power line standard offers more than 100 times the speed of the power line signalling meth- od most widely used today, and will enable communi- cation and control among electrical devices, sen- sors, and control systems in homes and commercial buildings. The Spread Spectrum Power Line Modem pusHBunoni TECHNOLOGY AT PRICES THAT WONT PUSH YOU OVER THE EDGE • Environmentally Engineered Formulations • Chemicals For AN Your Repair/Production Needs • Quality Products Since 1965 Call Today For More tnformaiion Manufacturers Reps Wanted WE DARE YOU TO COMPARE! llRCTg Wa $HOAC, 1^ TOnC 11T04 Yesterdsy's Vatuns, Tomorrow's T&chnoi€igy CABLE - TV TUNABLE NCTCI1 riLTERS ■ FOR ELIMINATION OF SEVERE INTERFERENCE ■ FOR "CENSORING' OF ADULT BROADCASTS • 45 da AT CENTER FRSQUENCy •SdB AT 2 MHZ FROM CENTER • 2dB insert™ LOSS MODEL TUNES TO CHANNEL PRICE SHIPPIMG 23H 2 or 3 [Of 6 rre(ef ham) S30 NO 46FM 4, 5. Of 6 1 or any FM sUilion) S30 SHIPPING 713 7.8.9, 10, 11, 12, Of 13 S30 OR 1417 \MAl tm. 16(C), Of 17(0) S30 c.o.a 1822 16(E) J9(F). 20(G). 21{H^ Of 22(1} S30 CHARGES 3 for $75-10 for $200 - Mix or Match 30 DAY MONEY BACK GUARANTEE (3 FILTER LIMIT) FAST DELIVERY CAU. TOLL FREE FOR C.O.D. OR SEND CHECK TO ORDER STAR CIRCLITS RO. BOX 9491 7 LAS VEGAS, NV 89193 1-800-535-7827 CIRCLE m ON FREE INFORMATION CARD (SSPMl built around the SSPM IC is said by Intel^ Ion to be the first inte- grated circuit to implennent the EIA s proposed CEBus power line physical layer standard. The 28-pin chip operates at the CEBus standard rate of 1 0.000 "I " bits per second. It gener- ates and receives all the re- quired signalling informa- tion, handles the CEBus physical layer protocol, and assists the higher-layer protocols. The modem board, which can be at- tached to a power supply and a host microprocessor that supports CEBus pro- tocols, helps speed ap- plication development by freeing engineers from de- veloping and testing the power line network hard- wane. The evaluation system allows developers to evalu- ate CEBus and Spread CIRCLE 21 ON FREE tNFORMATION CA8D Spectrum Carrier tech- nology and to implement a demonstration CEBus CSMA network that com- municates over AC power wiring, which can be used to model and analyze net- work characteristics by creating and running vari* ous traffic-loading sce- narios. The system in- eludes software that runs on any IBM or compatible PC and three complete CEBus network nodes. It features an electronic mail system to demonstrate the network and its ca- pabilities. The evaluation system costs S3.495; the SSPM chip and the modem board (pictured) cost less than $5 plus a one-time. $2500 li- cense fee in OEM quan- tities and $105 in quantities of ten, respectively — In- tefloit Corporation, 5150 West Highway 40, Ocala. FL 32675: Phone: 914-237-7416; Fax: 914-237-7616. BEZEL SELECTION. De- signed for use in the elec- tn^nics industry as a frame for LCD displays, tit's Bezel CIRCLE 22 ON FREE INFORMATION CARD Beautifut comes in four popular sizes that fit most LCD small-character dis- plays. Available in colors (red. yellow, and blue) as well as black and white. Bezel Beautiful is molded in UL-iisted. machinable, en- gineering-grade plastic. Molded with a slightly con- cave, outward curve from mounting edge to mount- ing edge, the bezel auto- matically adjusts itself to align without any gaps or spaces against any panel. Once mounted, it will re- main flat on the face of the product to which it has been bonded for the life of the unit. It can be attached using the heat-seal meth- od, sheet-metal screws, or a glue gun. The bezels come in four sizes, with measurements in inches for the viewing area of 1x2.5. 0,7x1.8. 0.7 X 2.5. and 0 J x 3.5. rtn Save on cable rental fees! € ICABLE TV I IDESCRAMBLERSI tWE'LL BEATS I ANY PRICE I 5 JERROLD-TOCOM-ZENITH 5 S HAMLIN-OAK-PIONEER J SCIENTIFIC ATLANTA S I I - 24 HOUR SHfPMENTSf ' MONEY BACK GUARM4TEEi • OUANTITY DfSCOUNTSf MASTER CAHD / AMDC / VISA / aO.D. Have make and model number of equipment used in you area ready. I CALL TOLL-FREE 1 1-800-284-8432 ^ I CABLE WAREHOUSE § 0 101 17 West Oakland Park Blvd. ^ Suite 5 IS, Sunflse, FL 33351 f ^ NO FLORIDA SALES ^ CIRCLE 186 ON FREE INFORMATION CARD NO COMPLICATED ELECTRONICS. NO EXPENSIVE INSTRUMENTS: Home study course shows you how to make good money in VCR repair. An amazing lact: you can do more than four out of five VCR repairs with ordinary tools and basic fix- it proce- dures. Our home study pro- gram shows you how. Learn all of the systems, mechanisms, and parts of almost all brands of VCRs, With no expensive instru- ments. W^o complicated elec- tronics. No fancy workshop. The step-by-step texts and close personal attention from your instructor make learning easy. Texts, course materials, and tool kit are sent to your home. Graduate ready to make up to S50.00 or more per hour in your own spare- time or lull -time business. Send today for your free career booklet. Or call 800-223-4542 Name City . State . Zip. The School of VCR Repair 2245 Perimeter Park, DeptVA342 .Atlanta. Georgia 30341 Bezel Beautiful is priced at less than a dollar each in OEM quantities. — Inter- national Instrumenta- tion Incorporated (1111. Box 3751, Thousand Oaks. CA 91359; Phone: 805-49S'7673, TRI-FIELD METER. The 7h- Fietd Meter from AlphaLab mdependentiy reads AC electric fields, AC magnet- ic fields, and radio/micno- waves with muiti-direc- tional sensors that read field strengths in all direc- tions simultaneously. It reads all three types of fields numerically and with a safe/borderline/high scale, weighted propor- tionally to the fields effect on the body Thresholds are based on epi- demiological and laborato- ry studies. Although no absolute hazard thresholds have been established, re- r CIRCLE 23 ON FREE INFORMATION CARD duction of relative ex- posure is advised. The meter conr>es with bat- teries, instructions, and a one-year limited warranty TheTri-Field Meter costs $100 postpaid. — Alpha^ Lab. 1272 East Alameda Ave., Salt Lake City, UT 84102; Phone: 503-621 -9701. 32'SWITCH CONTROL CARD> An eight'bit comput- er board from AccuSys. dubbed the 32 Switch Reed Relay Card grves any PC the ability to select and control 32 analog or digital signals with ease. Any sig- nal up to 100 voits and 10 vvatts can be controlled by the computer Because there is no addness limit to the number of boards that can co-reside in a single PC. one computer can control the connection of hundreds of signals by plu- gging in as many switch cards as there are available slots. The 32 Switch '■ X V : --I I I I I ! CIRCLE 24 ON FREE INFORMATION CARD Cards ability to route multi- ple analog signals through a single interface elimi- nates the need for redun- dant modems. When com- bined with higher capacity external relays, the card is capable of more active functions. For instance, when combined with an ap- plication that senses ener- gies, it can switch off water heaters and household ap- pliances when they aren't needed and automatically close ventilation systems or call the police or fire de- partment when sensing a fire or break-in. The 32 Switch Reed Re- lay Card, including soft* ware interface examples with source code in As- sembler, BASIC. C, For- tran, Cobol and dBASE, costs $395 — AccuSys, Inc, 3695 Kings Row, Reno. NV 89503: Phone 702-746-1111. I 28 The World's Most Popular Probe Model SPIOO 100 MHz SwitchabTe Ix-lOx . . 43 l^rec pr More SPIOO Probes Have Been Sold Worldwide Than Any Other Probe Ever Made • Universal For Tektronix. HewlctI Packard, FhilipK, Leader, B&K. Kikusui, Hitachi, Beckman and oiher OKCillOSCOpCS Economical Subsiantial savings compared lo OEM probes 10 day return policy Guaranteed pcrfonnancc and i|Uiitity TEST PROBES. IHC. TPI tJ17S Brown Deer Road, San Diego, CA 92121 Toll Free 1^800-368-5719 Try the bulletin board system (RE^BBS) 516-293-2283 The more you use ft the more uselul it becomes. Wb support 1200 and Z400 baud operation. Parameters: B^M (S data bits, no parity, 1 stop bit] or 7E1 (7 data bits, even parity, 1 stop bit). Add yourself to our user fifes to increase your access. Communicate willi other H-E readers. Leave your comments on R*E with the SYSOP. RE^BBS 516-293-2283 CIRCLE taa ON FREE INFORMATION CARD GET THE LATEST ADVANCES IN ELECTRONICS WITH A SUBSCRIPTION TO f. iUILD A SOUI^STATE LASEH! Our handheld laser runs on batceriBsl wMArs THE FtnuRi or SATEUm tv? A knli Bt how Lhe latest cbreot-bro^i^aft prapoeala are wned St cable TV SCSEEM YOUR TELS'HONE CALLS ELECTRQNJCALLYI By bulging our ceJ3 screafier SUtLD A POITTABLE QUAD ANTENNA A hifl^>f»rfonTianoe ar^penna for JUi ENJOY THE WORLD OF ELECTRONfCS EACH MONTH! Now you can subscribe to the best elec- tronics magazine. The only one that brings you articles on— electronics projects, tech- nology, circuit design, communications, new products and much more. Radio-Electronics looks to the future and shows you what new video, audio and com- puter products are on the horizon. What's more you 11 find helpful, monthly depart- ments such as Video News, Equipment Reports. Hardware Hacker, Audio Update, Drawing Board, Communications Corner All designed to give you instruction, tips, and fun. Radfo-Elactronics gives you excittng articles like: □ ISDN: The Telephone Network of Tomorrow □ The Facts on FAX □ A Digital Phone Lock □ How To Desigr> Switching Circuil!? □ EIA*232 A real standard for serial interfacing? □ Build a synergy card for your PC U "386 Power at a '286 price □ Build a biofeedback monitor □ More on Mylliplexir^g FOR FASTER SERVICE CALL TODAY 1-800-999-7139 DONT DELAY SUBSCRIBE TODAY! Just fill out the order cord In this magazine and mail it in today. SREAS NEW LIT Use The Free Information Card for fast response. HOW TO SERVICE YOUR OWN TUBE AMP; by Tom Mitchell, Media Concepts, RO. Box 1408, Narwalk, CT 9065M408; 213-594^4717; This "how-to" course is a complete multi-media package that consists of a 247-page guidebook and a 68- minute videotape, stored m a plastic binder Designed to save musi- cians money, the program instructs guitarists on the care* servce. and modi- fication of their tube based guitar amplifiers. The au- thor claims that, by follow- ing the instructions in the course, users can diag- nose and repair more than 95% of all tube amplifier bfeakdowns and problems. CIRCLE 2B ON FREE INFORMATION CARD In a nontechnical, informal, and entertaining style, the program introduces gui- tarists to electronics, ex- plaining how to recognize components, exploring basic amplifier circuits, de- scribing tools and test equipment, and providing gj in-depth coverage of tubes, a transformers, speakers. ^ and enciosures. It dis- g cusses how to read sche- ^ matic diagrams, how to ^ troubleshoot with voltage I charts, biasing, and thecor- ^ rect ways to use an ampli- her. Included are voltage ^ charts for most common £ amplifiers, ten trou- bleshooting flowcharts, a 30 maintenance checklist, and useful reference informa- tion. Several dont-yourself amplifier modifications are also described. HMC FULL LINE CATALOG; from Hub Material Compa- ny, 33 Springfield Avenue. Canton, MA 02021; Phone: 617-821-1870; Fax: 617-821-4133; free. Containing a broad se- lection of pnoducts for elec- tronics professionals and hobbyists, this 142-page catalog features a full in- dex, a table of contents, and CO I or- coded pages to help readers find specific items. The fully-illustrated guide to electronic tools, test equipment, and sup- plies for the manufacture, assembly, and repair of electronics contains a vari- ety of brand-name, com- petitively priced products. CIRCLE 25 ON FREE INFORMATION CARD Included are tesi instru- ments CDMM's, oscillo- scopes, and datacommuni- calions and telecom- munications test sets)* tool kits and precision hand tools, soldering and deso- Idering systems and sup- plies (fluxes, solder, tips, wick, and sponges)* lamps and magnifiers, and anti- static devices (bags, wrist straps, mats, runners, meters, and ionizers. Prod- uct descriptions are ac- companied by pho- tographs and prices, as well as "Tech Tips"' and comparison lables to make selection easier. HOLIDAY 1991 HOME AUTO- MATION BY HEATH; from Heath Company, Dept. 350-058. Beoton Harbor Ml 49022; Phone; 1-800-44- HEATH; free. Consumer products de- signed for safety, security, convenience, entertain- ment, and energy manage* ment are featured in this 40-page, full-color catalog CIKCtE 2h ON FREE INfORMAT^ON CARD Aimed at do-it-yourselfers and electronics hobbyists, the catalog introduces sev- eral new productSp includ- ing an electronic drape controller that allows drap- es to be controlled by a handheld remote or be pro- grammed to open or close at set times throughout the day three air cleaners that electronically deep-clean (he air, a gas detector that sounds a loud alarm m the event of a poisonous or ex- plosive gas leak, and a wireless add-on light switch for installation in staircases or long hallways that need a light switch at each end. Also featured in the catalog are whole- house automation and se- curity systems, motion- sensing indoor and out- door lighting controls, se- curity cameras, wireless video broadcasters, and energy-saving ther- mostats. The catalog pro- vides technical information on the products, and ex- plains how the products work. Such topics as pas- sive-infrared technology. X-10 technology, and how time is measured are also discussed. AUDIO FLYER; from Parts Eipress, 34D East First St., Dayton, OH 45402-1257; Phone: 513-222-0173; Fax: 513-222-4644; free. Audiophiies and elec- tronics enthusiasts alike will appreciate the selec- tion of goods offered in this 44-page, full-color catalog. CIRCLE 27 ON FREE INFORMATION CARD The catalog is filled with au- dio sound components and accessories; cables and wires; audio accessories; cables, speaker en- closures, woofers, mid* ranges, tweeters, and full speaker systems: P.A. equipment: and cross- overs. Highlights of this is- sue include decorative wall plates and accessories for in-wail mstatled audio sys- tems: t2-gauge neon wire: in-wall speakers; several woofers: and an iso-tip butane soldering iron. R-E A Shocking Offer! Now for the first time in CIE's 56 year history you do not have to be enroHed at CIE lo receive our Electronrcs and Electricity Lesson Modules. Available for a limited tJme to non-students for the shockingly low introductory price of only S99.50. With CIE^s patented AUTO- PROGRAMMED method of learning you1l quickly leam and then master the basics of electronics and electricity and then move on to soldering techniques, applications of Kirchhoff's law, voltage and power, printed circuil boards and much, much, more. Your commitment to CIE ends with your payment, but CIE's commitment lo your success just begins when you receive your lessons, exams, binder and equipment. This special price includes the benefits CIE normally extends to its students and graduates. You'll receive CIE Bookstore privileges, a pat* ented learning method, access to CIE's student, faculty and alumni electronic bulletin board and a free issue of CIPs school newspaper "The Electron". 24-Hour grading and unlimited access to CIEs faculty is available on an optional basis. And best of all, when you decide to continue your eiectro- nics education in any of CIE's programs, you'll receive a $100,00 CIE tuition credit certificate. All this knowledge and sup- port will put you on the road to understanding digital electronics, microprocessing principles, computer systems, telecommuni- cations, and much, much, more. » free issue of "The Electron*' ' BuUd your personal burglar alarm ' Theory and hands-on training lessons and exams covering ''current and voltage " through ^'printed circuit boards*' * CIE Bookstore privileges * Patent learning sriethod ' Electronic Bulletin Board privileges AIIThis ForBnIy! sAAso * A $100.00 CIE TUITION CREDIT CERTIFICATE Yes, send me CIE*s Introductory Electronic and Electricity Lessons and Equipment a7»i Name: Street: City: _ Apt. #: State: Age: _ .Zip: Phone {_ BOOKSTORE 1 776 East 1 7th Street Cleveland, Ohio 44114 Total Merchandise: Ohio Residenls add Sales Tax: Caldomia Residents add 6 \i2% Saies Tax: Total this order: Shipping arKl Hand^rng Charges: Method of Payment: Amount Encfosed: T Personal ChecJi or Money Order "1 Master Card TVrsa S5.tK) Card Expiration Date: Signature: I ^^^^^ CHARGE BY PHONE! 9 AM to 4:30 PM Eastern Time; 1-800-321-2155 ext, 7301; In Ohio 1-800-523-9109 ext. 7301 o s K PARTS NEW] Now YouVe Talking! This book wilt help you earn your first Amateur Radio li^ cense and gel on the aif. It in- eludes all the questions on the new codeless Technician class exam and the Novice written exam. The book also provides helpfuJ lips on equipment and antennas. Illusiraied^ Over 300 pages. #62-2414 . . 1G.95 Mercury Bulb Switch, Just the thing for motion detectors, alarms, experiments and school science projects. Rated 2 amps at 12VDC, Compact Vh size envelope. #275-040 1.29 Special -Order Hotline. Your local Radio Shack slocks over 1000 popular electronic com- ponents. Plus, we can special- ordor over tO.OOO ttems from our main warehouse— ICs, semiconductors, tubes, crys- tals, even SAMS' n^anuais. No postage charges or minimum reqyirements tor this service. Come in for details^ (1) Two -Tone Plezo Buzzer. Extra- loud. Operates from 8 to 16VDG. #273-070 ..... 10.§5 (2) Electromechanical Buzzer Loud 12VDC bu^er in a sturdy metal case is great for alarms. #273-051 2,49 NEW! PC/XT Experimenter's Circuit Card, This premium - quality prototyping board fits a computer's XT expansion bus connector Features durable epoxy glass construction and plated -til rough holes on stan- dard 0.100" centers. Accepts D-sub connector shown at right. x lOVis k Visl #276-1598 29,95 (1) Stackable Banana Plugs, Jack permits "chain" hook* ups, #274-734, Set of 27159 (2) Nylon Binding Posts. hZlA^mZ Set of 2/1,59 (3) Mlcro*Ctip jumpers. 20" long. #278-017 . . . Patr/3.49 (1) NEW! Right-Angle D- Sub 25 Female Connector* Ideal for use with PC/XT circuit card at loft. #276-1504, 2.49 (2) Box /Board Combination. Molded box and 2x3V9" cir- cuit board. ^270-291 . , , 4.99 (3) 2" Slim Alligator Cilps. #270-346 . . Pkg. of 8/2.19 i4) Cordless Phone Handset Antenna. #270>1411 . . . 2.S9 Super' Bright Strobe Tube. Perfeci for photo replacement, hobby projects and experi- ments. Trigger: 4 kU Anode: 200V min, Butb is aboul 1 V?^' long and has l^-*"* leads. ^272-1145 3,29 Si 5 8 UJ 32 (1) High-Speed 12VDC Mo- tor. Up to 15,200 RPMi About 2" long. ('^273-255 2.99 (2) Low- Voltage Motor, For science projects and solar power demos. Requires Vh to 3VDC. #273-223 . , . 99C (1) Lead*Free Solder. 96% tfn. 4% Silver. 0.032* size. 0.25 OZ. ^*64-025 1.99 (2) Rosin Sofderlng Paste Flux, 1 oz. #64-021 1.79 Over 100 soldering items and tools for electronics are in Stock now at Radio Shack t nj Hl-Precfsion Thermistor. Resistance changes in propor- tion to temperamre. #27MI0 ... 1.99 (2) 509- Piece Resistor Set, V4-wail. 5% tolerance. In- cludes 54 popular values. ^i*271-3!2 Set 7,95 Car Electrical System Tester. Spot pfob^ems before you* re stranded! Plug this analyzer into your vehtcte's lighter socket. Color- coded LEDs pin- point problems in your ballery, alternator and regulator, #22*1&35 .......... 5.95 Since 192t Radio St^ack ha^ been the place to oMain up*to-date electronic parts as well as quality tools, test equipment and accessories at low prices. Our nearly 7000 locations are ready to serve you— NOBODY COMPARES Pttti jtpp^ at parucipitirtf Rjctio STiack slores a-td ieikn. Ridlo SlUcii a t iotmin ct TiFKjy Corporjiiofi CIRCLE 78 OH FREE INFORMATION CARD . Itatff 0 /hack AMEtae/t'S TECHNOLOCV STORE ' siNce f »f How American Cablevision^s ^^butteV^ zapped signal pirates. KEN FOLEY ON WEDNESDAY. MARCH 13. 1991, American Cablevlsion of Queens fired their first infamous elec- tronic **bullet/" According to American Cablevision, they fired a direct hit. Within minutes their switchboard was overloaded with calls from subscribers whose television sets had gone black. American Cablevision was ela- ted — the victims had unsuspec- tedly taken the bait. The next morning, American Cablevision sent armies of tech- nicians to service the homes of the complaining customers. They replaced the cable converter boxes, and took the dead boxes back to the electronic coroners laboraton; performing hundreds of autopsies. According to official American Cablevision records of the mass epidemic, the "Certifi- cates of Death ' were identical — Illegal chip "zaps On Wednesday April 24, 1991, American Cablevision filed a civil suit in New York City federal court against three hundred and seventeen alleged cable pirates. That was the first time such a large number of cable crooks had been arraigned togcthen Ameri* can Cablevision offered the de- fendants a deal: Pay five hundred dollars within twenty days, or face prosecution and fines from one thousand, to one hundred and ten thousand dollars. "i think this is something that eveiybody's going to have to start doing," said American Cable President Barr>^ Rosenblum, American Cablevision has ap- proximately three hundred and thirty thousand paid subscribers in Queens and Brooklyn, and es- timates it forfeits hundreds of thousands of dollars each year to video marauders, and plans to fire more bullets. The electronic m a 33 bullet is the brainchild of Jerrold ComiTiunicaUons of Hatboro, Pennsylvania. It was first fired in 1990. by Greater Media Cable of Philadelphia. In three separate assaults. Greater Media Cable blasted away, netting three hundred and sixty eight illegal converters, which garnered a bounty close to twenty thousand dollars. Wc spoke to Jim Bathold. spokesman for Jerrold Commu- nications, to confirm American Cable vis ions story that the elec* tronic bullet is a signal fired from a cable companys headquarters directly Into a customers cable convener If the box is legitimate, the customer never knows he was just zapped. But if black- market chips were installed in a basic converter to circumvent paying the monthly service charge, the bullet uses the chips own programs to neutralize the decoder and halt the cable service immediately Mn Bathold then elaborated *Tes, that is basically how^ the bullet works," he confirmed, "But it would not be in our best interest to elaborate, or explain the operational procedure in de- tail* Otherwise it tells subscrib- ers, 'Here wc come/ We have not put one word out there in writing of how it works — no press pack- ages or news releases. We es- pecially wouldn't go into detail with electronic hobbyists," he choked out laughing. Hoping to fare better in Jer- rold s engineering division, we were fortunate to reach an engi- neer that was also a reader of ELa- dio-EIectronics. His boss' boss, technical engineering super- vison Stan Dorl» said: One of the approaches pirates have been taking for years to defeat scram* bling is to physically use a de- ^ coder box to unscramble the scrambling method. That is, to ^ reverse engineer the legitimate g descramblcr's software. ^ The bullet came into being be- 3 cause one of Jerrold s customers I (a cable company) told them of g rumors that pirates were defeat- ^ ing Jerrold's scrambling tech- nology. And the cable company ffi wanted to aggressively pursue them. So Jerrold acquired a 34 number of the pirate devices through various methodologies, and reverse engineered them so that a counter measure could be developed. That counter measure was the bullet, an offensive sig- nal thai Jerrold can send down the data stream to neutralize what the pirates reverse engi- neered. That s the bullet — dou- ble-reverse engineering, Dori continued, "So by under- standing what the pirates are doing and not doing to defeat cur- rent technology, we Ye able to launch a counter-offensive sig- nal, the bullet, to defeat them." In the hope3 of discouraging customers from buying illegiti- mate descramblers, information regarding the bullet is being leak- ed from the cable industre which claims they are losing up to three billion annually from piracy. According to Jodi Hooper of the National Cable Television As- sociation, "People think cheating on cable services is like a school prank. They don't really think iJiey are committing a crime and stealing. They just don t take it seriously, " Hooper also Indicated that some cable companies are offering complete amnesty to people who come forw-ard before their systems are audited and the bullet is released. She says if the culprits wait until they are dis- covered, they will chance the pos- sibility of criminal prosecution and heavy lines. Richard Aurclio. president of Time Warner's New York City Ca- ble Group, compares cable piracy to shoplifting. "Now that wc have the technology* we re going to use it to rope them in/* But its a mi- graine for the cable industry Most of the cable companies be- gan scrambling their satellites In 1986, and are now concentrating on detecting people with de* coders and illegal hookups. The National Cable Television Association says about eight mil- lion homes nationwide are linked illegally to basic cable signals. And an additional three million homes illegally tap into pay ser- vices such as Cinemax and HBO. But from 1975 through last year, the number of basic service subscribers nationwide grew from nine million to fifty- five mil- lion. The U.S- Telephone Associa- tion reports thai the average basic cable rate nationwide jumped sixty-eight percent be- tween 1986 and 1989. So even though the cable com* panics are reporting that losses from theft hav^e tripled during the same period, cable industry revenue has jumped about seven- ty percent from over ten billion in 1986 to almost eighteen billion last year. Such large revenues have caused some consumer groups to become skeptical of the cable companies claims of being finan- cially wounded by theft. 'There is no justification for using spec- ulative high-Lheft figures to justi- fy outrageous rate increases/' says Ken McEldowney, head of San Franclsco-based Consumer Action. Another method the cable com- panies are using to detect pi- rates, is the "closed circuit radar gun," or time-domain reflec- tometer. The major draw^back with the refiectometer is that it has to be physically attached to the cable entering each home to detect unauthorized connections or decoders. Other than that, sleuthing is still done primarily by inspectors who spend their days eyeball ing exterior cables for tampering. So naturally if the cable indus- try succeeds in scaring thou- sands Into confessing, it will score a two-headed \^ctory. First by recovering millions in lost rev- enue having people sign up — as was the case for Utah's TCI Cablevlsion In 1989 where they ran a biit?: advertising campaign showing guilt-ridden signal pi- rates imprisoned — and second by having the option of keeping the bullet in reserve as a secret weapon and not necessarily hav- ing to pay the heft>^ zapper fee to Jerrold Communications. Now Time Wamen the second largest cable company with over six million subscribers in thirty six states, is threatening to start firing bullets nationwide. Are they bluffing? If they are not bluffing, they will undoubtedly catch more ca- ble thieves who are foolish enough to run to their cable com- pany to complain that their pi- rated cable box is not working properly* R-E Build this sweep/function generator and frequency counter and add to your bench-top instrument collection. MICHAEL A. LASHANSKY IF YOU RE AN ELECTRONIC PROFES' sional or advanced hobbyist, you know the value of a vvell-equf pped workbench. An important piece of basic equipment Is a function generator and frequency counter. Although few professionals are missing one from their bench, many hobbyists can t justify the expense of quality commercial units. If you Ye one of those who has put oft buying such an in- strument, we can shovv you how to build one thai produces up to a 2.5'MH2 square, triangle, or sine-wave output with a 1 to 20- volt peak'to-pcak amplitude and a 20-dB attenuator This instru- ment also has a TTL or CMOS 0.5- to 15-volt peak output as well as a sweep generator and fre- quency counter that can read up to 150 MHz. All of these features are combined in a single bench- top unit, for a price of S300. Overview Our function generator and counter produces a square, tri- angle, or sine-wave output with a continuously variable amplitude of one volt to 20 volts peak-to* peak. A 20-dB attenuator allows smaller amplitude signals to be generated. A variable 0.5 to 15- voU peak TTL or CMOS pulse out- put is also available. You can vary the DC-level content, duty cycle, or invert any of those signals. The output frequency covers seven decades, ranging from 0. 1 Hz up to 2.5 MHz. (A higher fre- quency limit can be attained by making some potentiometer ad- justments, but at the expense of a degraded amplitude and wave- form shape, which we will dis- cuss in our next article,) Fine adjusting Is achieved through a linear dial. A six-digit LED indi^ cates the output frequency of the generator or it can be used to display the frequencies of exter- nal signals. tJsing the sweep generator, any of the output waveforms can be swept linearly or logarithmically by selecting the sweep width and/ or speed with the front panel con- trols. You can also sweep the se- lected waveform under the con- trol of an external voltage, which is useful for frequenc>' modula- tion generation techniques. The frequency-counter section can either give a readout of the frequency being generated or it can measure external signals. The counter's range is from DC to 150 MHz with an input sen- sitivity of 20 millivolts. Input sig- nals can be DC or AC coupled and the input impedance is swi tella- ble between 50 ohms and 1 megohm, A prescale/non-pre- scale function is provided to make maximum use of the six- digit LED to display high-fre- quency counts. The gate time of the counter is controlled by the frequency decade switches and ofTersgate times of 10» 1, O.L and 0.01 seconds. Theory of operation All low- to mid-end function generators — including this one^ — use a similar technique for generating a wavefonn. A basic triangle wave is first generated, then massaged into a sine wave and a square wave. The block di- agram of Fig- 1 shows the basic workings of the main board. A frequency-controlled multi- vibrator drives two current switches, which alternately charge and discharge a capacitor through a resistor. The resulting triangle wave is fed either through a sine-shaper circuit, a square-wave amplifier, or straight out to the output ampli- fier section. The output of the square- wave amplifier controls the polarity of the charging voltage of the capac- itor The capacitor will charge to positive, then to negative and back again to positive, thereby creating a triangle wave with an amplitude of 2 volts peak-to- peak. The waveform frequency Is controlled by the RC time con- stant and the amount of negative voltage applied to the multi- vibrator We will explore that in more detail later The output of the square-wave amplifier is also used to drive a TTL gate and CMOS level-shifter gate combination, which allows both TTL- and CMOS-level pulse outputs. The sweep-generator section is made up of a voltage controlled multivibrator with a long lime constant. That produces a DC voltage that varies according to the voltage applied. The output can be routed to a logarithmic amplifier to create both linear and log outputs. The signal is then fed to a buffer/level control amplifier which is then coupled to the voltage-control input of the function generators main multi- vibrator The frequency- counter section is made up of an input-amplifier signal'Conditioning circuit, a di- vide-by- 100 prescaler, an Intersil 7216B frequency-counter chip, and a six-digit LED, Signals are routed through the front panel for measuring. Prescaling de- creases the resolution of the dis- play but allows 150 MHz to be displayed with six digits. The decimal point on the LED indi* cates that the dlsplav is read in kHz. IViangle-wave genemtioQ Figtire 2 shows the schematic of the current switch and the tri- angle/square-wave generator, The combination of IC WC4 and Q1-Q4 makes up the main volt- age-controlled multivibrator A negative voltage is applied lo the inverting input of ICl, which FIG, 1~BLOCK DIAGRAM OF THE FUNCTIOJ^ GENERATOR. Note how the square-wave output is continuously fed back into the current-switch input. That is done lo precisely align the triangle and square wave output through the hysteresis loop to prevent crossover distortion. RG, 2— CURRENT SWITCH, TRIANGLE/SQUARE-WAVE GENERATOR schematic. The triangle wavc^form is generated by alternately switching current sources Q2 and Q4, thereby charging and discharging C103-Ct07. As the triangle wave crosses the upper and lower levels of IC3's input, a square wave is generated at the output of hysteresis comparator IC6. JO H Q. 9 m 37 drives the base of QL Compo- nents ICl and 91 form a current sink and 1C3 and Q3 form a cur- rent-controlled switch. Tlie amount of current flowing through Ql determines the switching threshold of 1C3. As the input of ICl (pin 2) becomes more negative, the output at pin 6 becomes more positive causing Ql to conduct more current. The collector current through Ql generates a voltage at (C3* pin 3. That voltage causes ICSs out- put to switch from one state to another The inverting input of ICS is connected to the positive rail through the switch-selected timing resistors RliS through R119. lYansistor Q3 switches be- tween on and off based on the amount of current flowing through the timing resistor se- lected and QL Components 1C2, Q2, IC4, and g4 perform the same function but are 180 de- grees out of phase. A triangle waveform is gener- ated by charging and discharg- ing the selected capacitor [C103--C107) by alternately switching current sources Q3 and Q4. The time required to charge and discharge the capaci- tor determines the period of one cycle and the frequency. Course frequency adjustmcnl is set by the chosen resistor-capacitor combination, and fine frequency control is determined by the volt- age at ICU pin 2. The triangle waveform is buff- ered by Q5 and transistors ICG-c and -d. lC6-a. -b, and -eacts as a balanced differential amplifier to form a hysteresis comparator which acts as a two-state latch controlling the direction of charging. As the triangle wave- form aUcmalely crosses the up- per and lower levels of the input (1C3* pin 2 and IC4. pin 2)» a square wave is generated at the output of the hysteresis com- parator That square wave is fed back to Q3 and Q4 to control the charging current path through bridge D101-D108. The square wave is fed back into the triangle wave input for alignment with the triangle wave. The importance of the hys- PARTS LIST All resistors are V4-watt, 5% unless otherwise indicated. R101— 2700 ohms, 1% R102. Rt04, R105, R109t R111— 100,000 ohms J % R1 06— 33.200 ohms, 1% R107, R108, R11 0—1000 ohms, 1% Rt12, R1T4-3010 ohms, 1% Rti3~49,900 ohms. 1% R115. R1 20-^990 ohms, 1% Rt16, R121— 7150 ohms. 1% R117, R1 22—348 ohms, 1% R118, R123— 75,000 ohms, 1% R119, R124— 750.000 ohms. 1% R125. R126. R826. R827— 10,000 ohms, potentiometer R127, R128— 5000 ohms, potentiom- eler (part of SI 01 and SI 02, respectively) R129, R825— 20,000 ohms, potenti- ometer R201, R210, R220— 10,000 ohms R202, R222— 470 ohms R203— 390 ohms R204, R206. R219-1000 Ohms R205. R216. R217— 2700 ohms, 1% R207. R208-^020 ohms. 1% R209— 611 ohms R21 1—30,000 ohms R212— 2000 ohms R213, R214— 13.000 ohms R215— 910 ohms, 1% R218— 7500 ohms R221— 47 ohms R223. R826— 5000 ohms, potenti- ometer R224, R225, R228. R229— 2000 ohms, potentro meter R226— 10,000 ohms, potentiometer (part of S201) R227 — 4700 ohms, potentiometer R301^9.900 ohms, 1% R302, R303^11.300 ohms, 1% R304, R306— 12,100 ohms. t% R305— 309 ohms, 1% R307— 200 ohms. 1% R308, R309— 24.900 ohms, 1% R310— 127 ohms. 1% R31 1—63.4 ohms, 1% R312. R313. R32Ch^1000 ohms R314— 5100ohms R31 5—080 ohms R3ie— 150 ohms R317— 6800 ohms R318, R319— 10,500 ohms, 1% R321— 2000 ohms R322— 12 ohms R323, R324 — 1000 ohms, potenti- ometer R325— 5000 ohms, potentiometer (part of S301} R401, R402, R503, R504— 10,000 ohms R403, R404— 22,000 ohms R405— 170 ohms. 1% R406— 12.000 ohms R407— 1200 ohms R408— 2000 R409— 18,200 ohms 1% R410— 270 ohms, 1% R41 1—100 ohms, 1% R412, R414. R502— 3000 ohms R41 3— 24,300 ohms, 1% R415, R4ia«-47 ohms, 1 W R416, R417— 7.5 ohms R419— 50 ohms, V2W R420— 499 ohms, VtiW R421— 56.2 ohms, 1% R422. R424 — 10,000 Ohms, potenti- ometer (R424 is part of S401) R423 — 200 ohms, polentrometer R501— 100,000 R505 — 10 megohms R701— 10,000 ohms R702— 100,000 ohms R703— 1 megohm R704 — ^50 ohms R705, R71S— 150 Ohms R706, R712— 220 ohms R707— 470 ohms R708, R715— 51 ohms R709-R711, R713, R714, R716, R717— 510 ohms R719— 36 ohms R720— 1000 ohms R801— 7500 ohms. 1% R802— 33,000 ohms, 1% R803— 33 ohms, 1% R804, R805, R807— 5100 ohms, 1% R806, R810, R816, R817, R819, R820, R822— 10,000 ohms. 1% R608— 510.000 ohms, 1% R809— 2200 ohms, 1% RS1 1—22,000 ohms. 1% R812— 2400 ohms. 1% R813— 100 ohms. 1% R815— 150,000 ohms, 1% R818— 15,600 ohms, 1% R821— 2000 ohms, 1% R823— 15,000 ohms, 1% R824— 18.000 ohms, 1% R830, R831— 5000 ohms, potenti- ometer {part of S801 and 8802, respectively) Capacitors CIOI, C102, C204, C205— 0.1 ceramic C103, C203— 100 pF, ceramic Cl 04— 0.001 p.F. Mylar C105— 0.01 tiF, Mylar C106— 0.1 fiF, Mylar C107— 1 ijlR Mylar Ct08. C504— 15-60 pF. variable capacitor C201 — 68 pF, ceramic C202— 0.047 jjlF, ceramic C301. C303— OJ ^xF, ceramic teresis loop (IC6 pin 4) Is to en- sure that the triangle and square wave arc perfectly timed to avoid any crossover distortion. The collector of 97 is clipped to approximately 3 volts by D218-D226and fed to IC7, pins I and 9, IC7 is a dual four-input AND gate, wtiich logically and*s the input square wave with a log- ic high to produce a TTL-level square wave output. The outputs of the two gates are tied together for increased current drive, and fed to the pulse-output control circuitiy The TTL square wave Is level shifted by Q8 to 15 -volt CMOS levels, were it fs NAwned with 15 volts in IC8-a. The output of the gate Is fed in paraOel to 1C8- b, -c, and -d, where they are also NANPed with 15 volts. The outputs of lC8-fa, -c. and -d arc connected in parallel for greater drive capability and routed through S201. a lOK po- tentiometer with a SPOT switch, which controls the pulse output mode. With the potentiometer in the OFF position, a TTL- level out- put is available. TUming the po- tentiometer throws the switch, which routes the CMOS output to the BNC connector J L The lOK potentiometer controls the amount of signal available to Jl and will vary 3ie amplitude of the signal from 0,5 volts to 15 volts. Figure 3 shows the schematic of the sine shaper and output amplifier Sine-wave generation is accomplished by taking the tri- angle wave from IC6-d and feed- ing it through the nonlinear network made up of D301-D312 and resistors R301-R310. The circuit attenuates the input tri- angle wave according to its level, producing a sine-wave equiv- alent. The output of the sine shaper is fed through a high- pass filter to the input of IC9, a CA3030 op-amp, Zener diodes D313 and D314 drop the 15-voU supply voltage to ±11.3 volts to accommodate the ±12-volt re- quirements of the IC. The gain of IC9 is about 10. and can be ad- justed by potentiometer R323. The CA3030 is an inexpensive wide-band op-amp but requires some frequency compensation to work over its entire bandwidth. C302, 0304, C502— 39 pF, ceramic C305» C401 — 4-7 pF, ceramic C307— 15 pF. ceramic C308, C40e— 5-35 pF, variable capacitor C402— 120 pF, ceramic C403— 2.2 pR ceramic C404, C406— 6.8 |iF, tantalum, 20 volts C405. C407— 0.047 jjiR ceramic C501— 33 pR ceramic C503 — 10 pR ceramic C601. 0602—1000 p-R efectrolyttc, 50 volts 0603, 0604— 100 ^jlR efedrolytjc, 50 volts 0605—1 ^iR tantalum, 20 volts C701, C704-C706— 0.1 fiR ceramic C702, 0707—100 pR ceramic C703 1 0u tantalum 1 6 volts 0801—22 \lF, tantalum, 16 volts C802, 0803—220 pR ceramic C804, 0805—100 pR ceramic C806— 500 pR ceramic Semiconductors D101-D108, D2O1-O204, D206-D226, D301-D312, 0315-D318, D401, D402, D701, D702, D801— 1N4148 diode D205— 1N751, S.l^volt Zener diode D313. D314-1N746, 3.3-volt Zener diode BR1— W02M bridge diode Q1, Q4, 012, Q13, Q21™2SC1815 or MPSA05 NPN transistor Q2, Q3. 06, 07, Oil, 019, 020— 2SA1015or2N4403 PNP transistor 05, 017— 2N4416. N-channel FET 06— 2N3904, NPN transistor 09. QIO, 014— 2SC1923 or MPSH34, NPN transistor Q1&— 2N2219. NPN transistor 016— 2N2905. PNP IransiStor 016— PN5139, PNP transistor 101, 102— LM741, op-amp 103, IC4— LM308, op-amp 105. 106, 1020— CA3086, NPN five- transistor 10 (Harris) tC7— 7420, dual 4-inpul and gate 108—4011. quad kawd gate 10^— 0A3030. op-amp 1010—4066, OMOS quad bilateral switdi ICn— 7216B, frequency ojunter and LED driver (Intersil) IC12— 7815, -flS-voltvotege regulator 1013— 7805, +5-V0II voJtage regulator 1014— 7915. - IS-volt voltage regulator 1015— M010116, ECL trip^e•line re- ceiver with Schmitt trigger (Motorola) 1016— SP8629. prescaler (Plessy) 1017— LM324, quad op-amp 1018— MCI 458, dual op-amp 1019— OA3140, op-amp (Harris) SR801 — 1000 ohms, thermistor DISP1»DISP6— common-cathode LED (FND357) Other components S1-S7--4PDT-D switch 58— OPDT switch 59- S11— DPDT-D switch S12-S14— OPDT-I switch S15— DPDT on/off switch 5101— DTDP switch used with R127 (5K potentiometer) 5102— DTDP switch used with R128 (5K potentiometer) S201— SPOT switch used with R226 (10K potentiometer) S301— OPDT switch used with R325 (5K potentiometer) S401— SPOT switch used with R424 (lOK potentiometer) 5801— OPDT switch used with R830 (5K potentiometer) 5802— DPOT switch used with R631 (5K potentiometer) J1^4 — BNC panel mount connector ^ J5, J14 — 8-position female/male, 0,1- j inch centers J6 — 5-position female/male, OJ-indi centers J7, J12— 2-pos4tion female/male. 0,1- inch centers J6, J13— 6-position female/male. 0,1* inch centers J9-J11, J15, J16— 4-position female/ male, 0.1 -inch centers XTAL1— 10-MHz AT/OUT crystal T1— 115/40 volts AO, 0.5-amp transformer Fl— 0.5-amp fuse Miscellaneous: Oase (OTP-1 by Global Specialties), three 1.75*inch standoffs, two TO-5 heatsinks. three T0-220 heatsinks, three PC ' boards, tntemal wiring, fuseholder, \ 3-oonductor 18-gauge power-sup- = ply cord and strain relief. Note: The following items are available from Tristat Elec- tronics, Inc., 66A Brockiogton Ores,, Nepean, Ontario, Canada, K2G 5L1, (613) 226-7223: • A set of three etched, drilled and plated-through PC boards — $76. • All components without the PC board and case — $250. • Complete kit of all parts (un- finished front panel)— S300, • Cut and silk-screened front panel — $10- Add $17 for shipping and han- dling. Send check or M.O, The main output amplifier consists of Q9 and QIO config- ured as an unbalanced differen- tial pair and transistors Ql 1-Qi6 configured as a complementary symmetry pusii-pull amplifien A differential amplifier amplifies the difference between the sig- nals present at the base of each transistor. The input signal is fed into the base of Q9 and the out- put of the push-pull amplifier is fed back through the attenuating circuit of R409. C403, and C408 ^ and coupled to the base of QIO, g The output of the differential ^ pain Q9 and QIO, is taken from g the collector of QIC with the gain g of that signal controlled by R408 and R423. which shunts the in- .| put signal to ground, B The DC content of the output % signal is determined by the DC *V bias voltage at the base of QIO =g (that value is set by potentiome- oc ter R422 and should be adjusted to give a O-volt DC level). Panel- 40 mounted switcii/potentiometer S401 allows the user to adjust the DC base bias of QIO, which causes the output signal to ride on a DC voltage from - 10 volts to -I- 10 volts depending on the po- tentiometer setting. The output of QIO is connected to the emitters of Qll and Q14 through DC blocking capacitor C402. Transistors Qll and Q14 are used in the common-base mode with the input signal fed into the emitters and the outputs taken from the collectors, TYan- sistors Q12 and Q13 are used as diodes to connect the collectors of Qll and Q14. The output of Qll is fed to the base of Q15, which amplifies the positive half of the signal. The output of Q 14 is fed into the base of Q16 which amplifies the negative excursion of the signal. Switch S301 con- trols the amount of signal enter- ing the amplifier section through the use of a potentiometen When the ganged DPDT switch is left In its normal in posit ion. the output will swing 20 volts peak- to- peak (open circuit). Pulling the switch attenuates the signal by 20 dB, Output Impedance is approxi- mately 600 ohms In the normal switch position and 50 ohms In the 20-dB position. The frequency-counter and sweep-generator circuits are shown in Fig. 4. The sweep gen- erator consists of IC17^1C20. The potentiometer section of S801 applies a negative voltage to the inverting Input of Integrator lC17-a, The input signal is inver- ted and charges C801 until it readies the switching tiireshold of comparator lC17-b. When the switching threshold is reached the output will go high» forward biasing Q21 which discharges C801 to ground through R806. The output at IC17-a pin 7 is a positive-going ramp and is routed through the linear/log se- lection switch S801 to either the output buffer amp or the log- arithmic ramp generator. 1 ? 3 4 ^ n 1 IV 1 F!Q. 4^SWEEP GENERATOR AND SIGNAL ROUTINa Potentiometer RSaO applfes a negative voltage to IC17-a; G801 charges until ft reaches the switctiing threshold of IC17- b, which then forward biases Ql . The output at IC17, prn 7 is a posttive-gomg ramp which is routed through the llnear/tog selection switch S801 to the output buffer amp or log ramp generator 1016 Is a prescaler chip used to downscale frequencJes greater than 10 MHz. An ant hlog generator circuit Is made up of IC17-C, IC18-a, -b, lC20-a, and -b. which performs an X'-^ function- [C17-cacts as an input buffer and attenuator, lC18-a and IC20-a drives the emitter of IC20-b In proportion to the input voltage at the base of IC20-a. The collector current of IC20-b varies exponentially with the emitter-base voltage. The cur- rent is then converted to a voltage by ampllMer lC18-b. Potentiome- ter R825 sets the balance of IC18- ds output between a linear and exponential function while po- tentiometer R826 controls the output signal level. Thermistor SR801 is necessary to compen- sate for temperature drift be- cause the output of the circuit is directly proportional to the anti- log of the input voltage, and the coefRcient of the log term is di- rectly proportional to absolute temperature. Without compensa- tion. the scale factor would also vary directly with temperature. Constant gain Is achieved by making the voltage at the base of IC20'a directly proportional to temperature. The linear and logarithmic positive- going ramps are buff- ered by IC19, a CAS 140 op-amp, and are converted to a negative- going ramp. That signal is then fed into ICl pin 2 through R102. Switch-potentiometer S802- R831 controls the negative volt- age that is coupled to ICl pin 2 when it is in the normal in position, ICl is controlled by the main frequency-adjust potenti- ometer SIOL which consists of Ri27 unconnected to SIOL With S802 in the our position, the output of 1C19 will be present at ICL Potentiometer S802 sets the ievel of the ramp and controls the sweep width. It should be noted that ICl pin 2 is a sum- ming point and the voltage pres- ent from the main frequency control and the sweep generator adds together. The sweep gener- ator starts its sweep at the point determined by the initial voltage at pin 2. For maximum sweep control, the main frequency ad- just potentiometer should be turned to Its minimum leveL Frequency counter The power supply and frequen- cy counter circuit is shown in Fig, 5. The frequency counter can count either signals gener- ated Internally or measure exter- nal signals. The external signal is switch coupled through SIl di- rectly through R70L or capacl- tively coupled through C701, as shown in Fig. 4. When the input signal is directly coupled, the low-pass filter of C708 and R720 is present. Capacitively-coupled signals by- pass the low-pass filter and pass through a high-pass fil- ter Diodes D701 and D702 clamp the input to protect Q17. Switch S12 selects the gate resistor and sets the Input impedance of the circuit. TVansistors 917 and Q18 provide amplification and imped- ance matching for IC15, an MCIOUG ECL triple-line receiver with Schmitt trigger. Differential amplifier Q19 and Q20 provide a single-ended output from the dif- 9 m 41 (Ct? 0 HUE saiCT {Stq .01 .1 1 •I' 1 *J_ CG03 ii-D|irLrLr| I +5V 1 I 1 1 1 1 1 I i 1 1 1 1 I I 1 ( 1 1 1 1 1 1 I DISP5 GCEPi DtSPt 0SP7 DlSP^I FIG. 5--P0WER SUPPLY AND FREQUEHCY COUNTS scfiematic. Either an internal or e^ctefnal signal source is selected via S14 (Fig. 4). Both signal sources are fed to JC11, a frequeficy counter and LED drivef chip. For input frequencies greater than tO MHz, prescaltng is needed. Terentlal outputs of IC15. Switch S13 controls whether the input signal is fed direcUy from the in- put ampiilier or from the divide- by-100 prescaler to the counter section. The counter section can take its input from the internal source or from an external source via S14. The Internal signal repre- sents the output frequency of the frequency generator and Is taken from the junction of D221 and D224. Both signal sources are pulled up to CMOS levels by R502 and fed into ICIL an Intersil fre- quency counter and LED driver chip. The chip combines a high- frequency oscillator, decade time- base counter, an 8-decade data counter and latches, 7'Segment decoder, digit multiplexes, and 8- segment and 8-digit drivers, which directly drive muUlplexed LED's. The Input frequency of the chip is limited to 10 MHz* so pre- scallngof the Input is required to measure higher frequency sig- nals. The 7216B is a multifunc- tional chip, performing many useful measuring tasks. A 10-MHz crystal, XTALi with components C501— C504 and R505 set the Internal timebase to 10 MHz, That configuration works well with our divlde- by-lOO prescaler because the timebase can remain the same, only the decimal point takes on a different meaning. In non-pre- scaled operation, the decimal point on the LED Indicates the reading is in kHz, when the input is prescaled, the decimal point Indicates the display Is read as xlO kHz. We'll discuss more about that later Gate-time selection is con- trolled by the main frequency se- lection switches Sl-d through S7-d. They are configured to give gate times of 0.01 seconds in the 1-MHz range, 0,1 seconds In the lOO-kHz range, 1 second In the 10-kHz through 10-Hz ranges, and 10 seconds in the O.l-H?. range. The gate time select (ICll pin 14) must be connected to the appropriate digit driver to select the required time. Gate- time selection is achieved by applying 5 volts DC from one of the switches Sl-d though S7-d to the control input of one of the quad*bilateral switches of ICIO. Each of the bilateral switches of [010 controls the digit driver that Is connected to the gatc-selecl In- put. Because switches Sl-d through S7-d are dependent (only one can be engaged at any one time] only one of the bilateral switches will have 5 volts on its control Input, all the others will be at ground. Resistor R504 hardwires the function select to Implement the frequency mea- suring mode only Both R504 and R503 are required to reduce ring- ing at the input, which could re- sult in false selections. The power supply is fairly straightforward. AC line current is switch-connected through S15 to fuse Fl to the primary of TL The transformer is center tapped with a secondary voltage of 40 volts and full load current of 0.5 amps. Diode bridge BRl rectifies the AC secondary voltage and it is filtered by capacitors C601 and C602, Voltage regulators, lCi2^IC14, provide +15, +5, and - 15 volts DC, The ±20 volts DC is taken right from the bridge circuit If a 40-volt AC secondary transformer cannot be found, Zener diodes can be used to drop a high secondary voltage down to the ±20-volt range. Next time well discuss how to build and test the function generator. ft-E SPEAKERPHONES WAVE COME A LONG way since the two-piece units we used to see on the 1958 TV series, The FBI. There, an agent, played by Ephrim Zimbahst Jn, sat on his chiefs desk as they *'con- ferenced'* around the country planning the capture of the vil- lain. In those days the units were available only by a rather expen- sive lease from Ma Bell, and the talk unit and receive section had to be located on opposite sides of jl the desk to avoid acoustic feed- back — the same sort of sound that a public address system gen- erates when the speakers are lo- cated too close to the micro- phone. Today thanks to some sophis- I ticated electronics, the speaker and the microphone can now be used in a single enclosure. How- I ever, as we will discuss later, there are still acoustic considerations to contend with. WeVe all heard what the typical speakerphone sounds like, and that's probably why most of us dont already oum one. Speakerphones have also had a history of being expen- sive—until now The Speaker-Mate speak- erphone is inexpensive, com- pact, easy to build, and powered from the phone line. You'll still need a regular phone because you can't dial out on the Speaker- Mate, and it doesn't have a ringer. But its sound quality is excellent. A qualit}^ speakerphone relies on a balanced combination of electronic design and acoustic physics. With the Speaker-Mate, once an enclosure was chosen, the microphone and speaker were moved to different positions to achieve the best possible sound before making the linal de- sign. Operation Modern speakerphones work on a switching principle to mini- mize audio feedback. Neither the talk path nor the receive path are totally off, but each are attenu- ated by a factor of 52 dB, and both sit in an idling mode until one person talks. IVs similar to voice-controlled transmissions (VOX) used by ham operators, where both station transmitters are off until one operator talks; 1^ when they are through the other g station can talk. The comparison ^ ends here because with a speak- g erphone, the receiving station ^ can interrupt simply by talking ^ louder. Figure 1 is a block diagram of m the Speaker-Mate- The talk path | goes left to right on the upper half | of the drawing, and the receive S path goes from right to left. Both paths go through their respective 43 attenuators which are controlled by the attenuator control block. That section gets its data from level detectors on both circuit paths. The detectors are inter- connected with background- noise monitors. One of the requirements of the speaker-phone design is to dif- ferentiate between speech, which constantly varies in amplitude, and constant background noise. When constant and unvarying noise is heard* the attenuator control mutes both paths until speech is read. A separate detec- tor is provided to attenuate the dial tone- it is not a single tone and does not qualify as noise. The Z balance network matches both paths to the phone line. RG. 1— BLOCK DIAGRAM OF THE SPEAKER-MATE. The talk path goes (eft to right on Circuitry the upper half of the drawing, and the receive path go€S from right to left. Referring to the schematic in Fig. 2, the 600-ohm balanced telephone line is coupled to the C6 g Q 2 in 6 44 24 CB 23 22 21 C14 gol 19 17 te fll3 '^47tiF 5.1 K 15 mo CPR RLII RLOl TL01 TLII RXO RXl RLI2 RL02 TL02 TLI2 CRT C5 Mb 56K C2 .{KJ5 CD ^cc HTO- HfO HTj TXO D(l MCO R5 220K .01 C27 ; lOOG^iF Jl MODULAR PHONE JACK — — ^ I — h SI cT HOOK J ? SWtTCH RS .05 10 C12 MCI MUT VIC R11 -OS JU1 (REMOVE FCM^ EXTERWAL POWfftJ % 01 R19 33K 14 C19 4.7Hf C17 ?20iiF Rt4 T2CIK CIS?^ .1 1MEG — SAVn R15 25K M1C R1& IK C20 ■ 1 C22S4^ .1 R17 IK — VNV- Blfl mm C25 47uF 7,: 6 5 ICS J V02 GNO v.. VOl IC2 MC3411SP CD FC2 FCl C24 .1 lOK C26 m R24 5JK : R?5 ■ 10- »■ s 3 S FIG. t--MONITOR EXERCISER SCHEMATIC. When operating the unit, make sure that EGAA/GA swilch S2 is in the proper position for the type of monrtor in use. An Improper horizontal sync frequency can cause damage to deflection circuits. FIG, 2— POWER SUPPLY. If you don*t have a suitable 5-volt DC power supply available, you can build this one. color sequence Is the reverse of VGAJ Vertical sync is generated by sending horizontal sync to pin 1 oflCB-a. a 74LS393 binary coun- PARTS LIST All resistors are V4~watt, 5%. R1— 24,000 ohms R2. R3— 5100 ohms R4, RIO, R1 3— 10,000 ohms R5. RTt— 100 ohms R6, R12— 1000 ohms R7-R9— 620 ohms R14— 56ohms Capacitors CI— 1000 plE 50 volts> electrolytic C2— to piR 10 voHs, electrolytic C3-C13, C16, C17~0,01 fiR 50 voltSp ceramic C\A — 0.022 ^jlR 50 volts, ceramic Cl5— 100 pR 50 volts, ceramic Semiconductors ICl— 74HC04 hex inverter IC2— 74HC14 hex Schmilt trigger inverter IC3, IC9— 74LS164 shift register IC4— 74LS74 D flip-flop ICS— 74LS163 4*bit binary counter IC6, IC7— 74HC158 2-line to Mine selector ICS— 74LS393 dual 4''bit binary counler ICtO— LM340T-5.0 5-voll regulator 0SC1— 5.0688-MHz TTL clock oscillator OSC2^.9152-MH2 TTL clock oscillator 01— 1N4001 diode 02, 03— 1N5711 Schottky diode Q1, Q2— MPS6515 NPN transistor Other components F1— 0-25*amp AGC fast-blow fuse J1 — DE9S 9- pin female connector J2— HD DB15S 15-pin high-density female connector SI. 82— SPST switch S3— DPDT switch Tt— 120/6-3VAC transfomier Miscellaneous: AC Nnecord, wire- wrap IC sockets, metal enclosure, wire, solder^ etc. ter, where it ends up divided by 64 at pin 10 of lCS-b and fed into the CLK input (pin 8) of IC9, an- other 74LS164 shift register. The CLR input to IC9 (pin 9) ultimate- ly comes from its own qg output via IC6s A2 input [pin 5}. its y2 output (pin 7), Schmitt inverter lC2-f, and transistor Q2. Using [C9s QG output to reset itself causes a division of its clock in- put by 7. Therefore, the horizon- tal sync is first divided by 64 by ICS, then divided by seven by IC9, making a total division of 448, Therefore, a 70. 71-Hz signal (3L68 kHz divided by 448) with a pulse width is sent from IC9 pin 3 to pin 14 of J2, a 15-pin high-density VGA connector, via CIS. R13, and Schmitt inverter lC2-e. CGA/EGAl operation When switch S2 is set to "EGA/' it places a logic (a high) on pin 1 of IC6, which then connects Its "B" Inputs to tiie outputs. When S3 is set to ' Mode 1." It places a logic "0" (a low) on pin 1 of IC7, another 74HC158 selector, which connects its *W Inputs to the *'Y" outputs. Now FIG, 3— THE AUTHOR S PROTOTYPE, Perforated construction board and wire* wrap techniques were used to assemhle the project. IC7 uses OSCl as its timing source which is input at pin 2 and output at pin 4. That, in turn, is input to pin 13 of 106 and output at pin 12. From pin 12 of IC6, OSCl is to IC3s clk input (pin 8). Because lC3s qe output (pin 10) is tied back to its clr input (pin 9) via IC7 pins 5 and 7, IC6 pins 10 and 9. RL and Ql, IC3 divides OSCl by five. Output QC of IC3» which is also OSCl/5 because qe is used as the clear signal, routes 1.014 MHz (5,0688/5) to pin 3 of IC4-a, caus- ing further division by four at pin 9of IC4-b for a total division of 20 (253,44 kHz). The 253,44-kHz output from IC4 pin 9 is con- necled to pin 3 of ICS via 1C7 pins 1 1 and 9. The input to pin 3 of ICS is output at pin 4. and from there it goes to S3 and the clk input of ICS (pin 2). After IC5 divides the 253,44 kHz by sixteen* the hori- zontal sync measures 15,84 kHz, Vertical sync is generated by di- viding horizontal sync (15.84 kHz} by 256 at pin 8 of IC8. That output connects to C12. Rl, IC2- b, and pin 14 of IC7, The 61 .88 Hz vertical sjtic signal with a 190 ^jls positive pulse width is then sent to pin 9 of output jack J 1 via 1C7 pin 12. EGA2 operation When S2 is set to "EGA," it places a high on pin I of 1C6, which then selects its "B" inputs. With S3 set to "Mode 2/* it places a high on pin 1 of IC7 so it also selects '*B" inputs. With the " B" Inputs selected, IC7 uses OSC2 as Its timing source and 4,9152 MHz passes from pin 4 of IC7 to pin 13 of 1C6. The signal then connects to IC3s clk input (pin 8) from pin 12 of IC6. The qg output from 1C3 is connected to 1C6 pin 10 via 1C7 pins 6 and 7, The signal is then output at pin 9 of IC6, and connects back to the ^ CLR input (pin 8) of IC3, The g OSC2 signal is divided by seven ^ by IC3 producing 702.17 kHz at ^ IC3s QC output. The qc output from 103 ties to 104 -a, which 3! causes an additional division by 9-. 2, for a net of 14, The 35L08 kHz % from 104'a pin 5 is connected to S IC5s CLK input (pin 2) via 107 3 pins 10 and 9, and 1C6 pins 3 and | 4, The signal is further divided by continued on page 94 49 WITH We begin our in-depth survey of opto- eiectronic systems by taldng a dose /oolr at a wide variety of LED circuits. RAY MARSTON OPTICAL ELECTRONIC DEVICES ARE SO Widely used in today's consum- er-electronics that its hard to come across a product that doesn't use light-emitting diodes (LED's) in one way or another, IT you've ever had a need to use LEDb or specialized flashing de- vices in your circuit, design, we might be of some help to you. We'll start by presenting some basic information on LED's, then well take a look at some multi- LED packages. Finally, well round-off with a discussion of different t>pes of flasher circuits used for controlling LEDs. LED basics LED -s are commonly used as vi- sual Indicators because of their fast response time and high effi- ciency When compared to tung- sten-filament lamps* their typical energy conversion efficiency is ten to fifty times greater and their response time is one hundred to one thousand limes fasten LEDk are widely available in red. or- ange, yellow and green colors. Figure 1 shows the standard LED symbol and typical forward voltages of different colored LEDls. The device Is a genuine dlode» and a voltage of approxi- mately 2 volts Is produced across it when it is passing a forward current of 20 miUiamps. If an LED is reverse biased, it will ava- lanche or "Zener" at a fairly low voltage value, as shown in Fig. 2. Most LED's have maximum re- verse voltage ratings in the range of 3 to 5 volts. O ANODE (A) COLOR RED ORAJJGE yellow] green Lev 2,1V ZZV nG. 1— LED SYMBOL AHO TYPICAL for- ward vottages of standard L£D^ at Ip^ 20 AVALANCHE HEGION RG, 2— GRAPH SHOWING REVERSE bi- ased LED responding as a Zencr drode. T v.- V, LED! FIG. 3r— METHOD OF RNDING the current- Nmltfng resistance value for a given Vg and If, When an LED Is used, a re- sistor or other suitable current- Unit ting device must be wired in series with it. The current-iimU- ing resistor value can be calcu- lated for a specific forward cur- rent, ip, and supply voltage, V^, as shown in Fig- 3, being. R = (Vs'Vf)%- In practical applications, the series resistor can be connected to either the anode or the cathode of the LED. The LED brightness is proportional to the LED cur- rent: most LED*s will operate safely up to absolute maximum currents of 30 to 40 milliamps. With a DC supply voltage and a suitable line dropping resistor, the current through the LED should be maintained at a con- stant value of approximately 20 milliamps. An LED can be used as an in- dicator in an AC circuit by wiring a diode in inverse parallel uith it, as shown in Fig, 4. The diode pre- vents the LED from becoming re- versed biased on the negative hair of the sine wave cycle. For a given brightness » the line drop- ping resistance value in an A0% circuit should be one half that used in a DC circuiL When an LED is used in an AC circuit, the forward current conducts through the LED only during the positive half of the sine wave cy- cle, after the LED has reached its threshold voltage of about i,5 volts. Therefore » the LED con- ducts current less than one half the time in an AC circuit as itj does in a DC circuit. In order achieve the same averajg^ecurrenli through the LED with an AC su[ ply approximately twice as muct current must flow so the resis* tance value must be reduced by one half. One of the first problems you will encounter when using an LED is identifying its polarity. The cathode on most LEDs is identified by a notch or flat sur^ face on the component, or by ^ short lead. That practice is not universal, however, so the only accurate way to identify the po- larity of an LED is to test it in the basic circuit of Fig 3 : try the LED in both positions, when it glows, the cathode is the most negative of the two terminals. It is always a good practice to test an LED be- fore soldering It onto the PC board. 0 LED1 B1 ,0 DT ^ lff40fflT FIG. 4— AN LED USED IN AN AC circuit; D1 is wired in inverse parallel ta prevent the LED from being reverse biased. Special mounting kits are available for securing LED's onto PC boards and front panels. Those kits consist of a special mounting grommet and grooved ring shown in Fig.S-a. If mount- ing hardware is not available, you can drill panel holes and ei- ther epoxy the LED into place or solder its leads into a PC board, which can support the LED. That method is siiown in Fig, 5-5- LED packages LED's can be purcliased as sin- gle components, as sho\^Ti in Fig* !, or in a multi-LED package. The most common type of muUi-LED package is the 7-segment display comprising seven or eight LEDs packaged for displaying alpha- numeric characters. Another MOUtfTlNG GHOMMET RTOmrNGfllNG f INSTALLED) LED. GROOVED RETAINING RING EPOXY EPOXIED LEAD WIRES P.C. BOARD BACKED BY P C, eOARO RG. 5— LEO MOUNTING METHODS: (a) shows an LED mounting krt conststing of a grommet anci retaining ring, and t^) shows an LEO mounted in a drilled hole with epoxy or soldered leads. well-known type of muIli-LED package is I he bar- graph display, which is made up of Icn to thirty linearly- mounted LEDs. An ex- ample of a ten-element LED pack- age is shouTi in Fig. 6-a, Most LEDs provide only a sin- gle output colon There are, how- ever* a few specialized LED packages that provide multi- color outputs. Those devices ac- tually consist of two LEDs con- tained in one package. Figure 6-5 shows a bi*color LED which Js comprised of a pair of LEDs con- nected in Inverse parallel. The color green is emitted when the device is biased in one direction. FIG, 6— MULTI-LED PACKAGES j (a) is a 10-element LED, and (b) Is a 2-color LED which contains two L£D*s connected in inverse parallel. and red or yellow is emitted when It Is biased in the reverse direc* tion. The bl-color LED is useful for giving polarity Indication and null detection. Another type of mult I -color LED is shown in Fig. 7. This four color LED is made by mounting a green and red LED in a 3-pin common-cathode package. That device can generate green or red colors by turning on only one LED at a time, or it can generate orange and yellow by turning on the two LEDs in the current ratios shown in the table. A ver^"^ important practical point concerns the use of "sec- ond-grade" or "out-of-spec" de- vices advertised as bargain packages. Those devices often have forward voltage drops in the range of three to ten volts. Al- KCS- mm -oh LED2 RED -OA COLOR OUTPUT RED ORANGE YEUOW 6RE£H LHJ1 CURRETfT SniA lOfnA 15mA LfD2 CURREMT 5mA 3mA 0 FIG. 7— MULTI-COLOR LED; this LED gives four colors from two {unctions as shown In the current ratios given tn the table. though "second grade" LEDs may be suitable for many applica- tions, its always a good idea to test those devices before using them in your circuit » as we said earlier Multi-LED circuits A number of LED s can be driv- en from a single source by wiring all LEDs in series as sho\\Ti in Fig, 8, The supply voltage used in that circuit is equal to the sum of the individual LED forward volt- ages and the voltage drop across the line-dropping resistor. The line-dropping resistance value can be calculated by using the equation R-(Vs-VftVIf^ The total forward voltage, Vj,-,,, is the sum of the forward voltage drop of each LED. The circuit shown in Pig, 8 draws minimal total current, but is limited in the number of LEDs that it can drive, A number of tiiose series LED circuits can. FIG, 8— LEDs WIRED IN SERIES and driv- en by a single current-limUlng resistor q, n :d m g_ a m B n 51 Fia 9— A NUMBER OF SERIES LED cir- cuits can be wired in parallel, to drive mul- tiple LED's. FIG.10— THIS CiRCUlT CAN DRtVE a targe number of LED% but at the expense of high current. FIG. 11— NEVER USE THIS LED driving cir- cuit One LED will draw ali of the current liowcven be wired in paralleh so that almost any number of LED s can be driven from a single source » as shown In the 6-LED circuit of Fig. 9, An alternate but less efficient method of driving multiple LED s is to simply wire a number of dropping resistors and LEDs in paralleL as shown in Fig. 10, That t\pe of circuit will worli* but it draws a significant total cur- rent, which is equal to the sum of the Individual LED currents. Since we're on the subject of how to conned multiple LEDs. lets discuss what not lodo. Never hook-up multiple LED*s as shown in Fig. 1 L That circuit will not work properly because of in- evitable differences in the for- ward-voltage characteristics of the LEDs, one LED will usually draw most of the available cur- rent, leaving little or none left for the remaining LEDs. Three widely used types of visi- ble-output LED-controi circuits are those used far LED flashing. LED sequencing, and LED dot or bar analog-value indication. LED flasher circuits are designed to kirn an LED alternately on and olT. to give an eye-catching dis- play action. Those circuits may control a single LED» or they may be designed to control two LEDs in such a way that one turns on as the other turns off. A special LED-flasher IC is available, the LM3909, which can be used to flash an LED from a low voltage DC supply and does so at a ver>^ low average current level. Some practical LED flasher circuits using the LM3909 IC are shown later in this article. LED sequencer circuits are de- signed to drive a chain of LEDs so that each LED In the chain is switched on and off in a time- controlled sequence, so that a ripple of light seems to run along the chain, LED analog-value Indicator cir- cuits arc designed to visually ap- pear and respond as an analog meter. An analog-value LED cir- cuit drives a chain of linearly- spaced LEDs in such a way that the length of the chain that is illuminated is proportional to the analog value of a voltage applied to the input of the driver circuit, LED-flasher circuits One of the simplest types of LED display circuits is the LED flasher, in which a single LED re- peatedly switches alternately on and off, usually at a rate of one or two flashes per second, A 2-LED flasher is a simple modification of this circuit, but is arranged so that one LED switches on when the other switches off. A 2-LED transistor flashing circuit is showTi in Fig. 12, In the flashing circuit showTi in Fig. 12, Ql and Q2 are wired as astable multivibrators, with their switching speeds deter- mined by time constants R3 xCl and R4 x C2, The circuit operates at about 1 flash per second using the component values shown. The 2-LED flashing circuit can be converted to slngle-LED oper- ation by replacing the unwanted LED with a short circuit. An IC version of the 2-LED flasher is shown in Fig. 13, That design is based on the depend- able 553 timer chip, or its more modem CMOS counterpart, the 7555, The IC is wired in the asta- ble mode, with its time constant determined by R4 and CL The output at pin 3 of the IC alter- nately switches between the ground and the positive supply voltage, alternately shorting out ^^6T0 9V '01 02^ ZII3704 210704 f iG. 12— TWO^LED FLASHER circuit oper- ates at t Hz: Qt and 02 respond as astabie multivibrators while LED1 and LE02 alter- nately flash on and off. FIG, 13— TWO-LED FLASHER circuit Oper- ates at 1 Hz using a 555 or 7555 timer IC. RG. 14— FOUR-LED DOUBLE-BAR flash- er in a "cross" configuration; the flashing rate is variable from IS to 200€ flashes per minute. and disabling LEDl or LED2, The flashing circuit can be con- verted to single-LED operation by shorting out ihe unwanted LED and its associated current-limit- ing resistor A visually interesting display can be produced with a useful modification of the above circuit, shown in Fig. 14. TWo pairs of series-connected LED's are con- nected in the form of a cross so that the visual display alternately switches between a horizontal bar (LEDl and LED2 on) and a vertical bar (LED3 and LED4 on) The flash rate is made variable via potentiometer R5 and can range between 15 and 2000 flash- es per second. Flasher IC LM3909 A seemingly trivial task that sometimes faces the design engi- neer is that of providing illumi- nated power indication of the ON state of an electronic unit or the location of a passive device such as a fire ext 1 ngu isher or emergen- cy switch in a darkened room, LEDs operate reliably when main power is available, but a serious problem arises when battery- powered equipment is involved. LED indicators typically draw about 12 milliamps when illumi- nated and can therefore place a fairly heavy strain on small sup- ply batteries. Since LED*s drop two or more volts under the on condition, they can not readily be powered from battery voltages be- low about 3 volts. National Semiconductor pro- vides an ingenious solution lo the problem of LED power drain and operation from weak bat- teries with the 8-pfn LM3909 LED flasher/oscillator IC, The LM3909 IC is a low-duty-cycic (brief on period, long off period) oscillator that provides a voltage- doubled, high-current pulse to an external LED, High pulse cur- rents of up to 100 milliamps are produced from the IC. while still drawing very low civcrage cur- rents of about 0.3 to L5 milli- amps. Because of the voltage- doubling capability, the LM3909 can flash an LED even when powered from batter>^ voltages as low as LI volts, and can provide months, or even years, of contin- uous flashing operation from a '7^ RG, 15— pical ex- ternal connections for 1.5-voIt flasher operation, are shown in Fig, 15, In that particular ap- plication, iliQ LED receives cur* rent via the 270-(jiF timing capacitor CI, Rl, and Q3 for only about 1% of the time. All tran- sistors except 94 are off for the remaining part of each operating cycle. Resistor R9 draws only about 50 |xA, The timing capaci* tor 01 is charged through R2 and UW39Q9 tLBl T.5V CELL SIZI ESTIMATED B/SffTEBY LIFE UNDER COIfTJNUOUS 1.5V OF FLASHER OPERATION smotm CEa ALKALINE CELL AA zmrnns 6 tAONTHS C 7M0tfTMS 15 MONTHS D 15 mmns 30 MONTHS RG. 16— LED FLASHER USING 1.5 VOLT SUPPLY. TABLE shows estimated battery life under continuous 1.5-vott LED flashing operation. LM39D§ Q^LEDI B1 _J L5V FIG. 17-MINiMUM POWER, longer life, 1.1-Hi flasher. Average drain current Is 0.32 milliamps. FIG, 18— FAST 1.S-V0LT BLINKER; flash rate Is 2.6 Hz and drain current is 1>2 mllll- amps. RG. 19— VARfABLE-RATE FLASHER. R3 and throui^h R5 connected be- tween pins 1 and 4 of the IC. IVansistors Ql through Q3 re* main off until CI becomes charged to about I volL That volt- age is determined by the junction drop of Q4. Its base-emitter volt- age divider, consisting of R6-R7, and the junction drop of QL When the voltage at pin 1 be- comes a volt more negative than that at pin 5 ( + V^^). Qi begins to conduct and turns Q2 and Q3 on. The !C then supplies a pulse of high current to the LED, The cur- rent gain of Q2-g3 is approxi- mately 500, Transistor Q3 can handle over 100 milliamps of col- lector current, and rapidly pulls pin 2 close to ground, pin 4. Since CI is charged at that time, it forces the pin 1 terminal below ^ the ground potential value. As a g result of the pin 1 terminal being ^ less than the ground potential, g the one-volt drop across the LED ^ is greater than the supply voltage S value— Rl then limits the LED current to a safe ralue. 123 Capacitor CI alternately S charges via the timing resistor f R5 and discharges via the LED S and Rl in this application. In some other applications, the S3 short between pins 1 and 8 can be removed, enabling the capacitor to ctiarge through a total of 9 Icllohms, increasing the duty cy- cle and reducing the average cur- rent drawn. If voltage boosting is not needed, loads can be wired directly between pins 2 and 6 or pins 2 and 5 of the IC. The LM3909 IC is thus a fairly versatile device. A variety of useful applications are shown in the remaining part of this art icle. Practical LM3909 circuits The LM3909 circuits shovvTi in Figs. 16 and 17 can be used as locator beacons for fire ex- tinguishers, emergency switch- es, and boat-mooring floats be- cause of their low voltage operation and low current drain. The circuit shown in Fig, 16 gives a brief flash once every second or so, and typically draws an aver- age current of only 0.63 milli- amps. As shown in the table, that circuit will continually operate for three to thirty months from a battery, depending on the size and t>pe of cell that is used. An even longer life can be ob- tained from the minimum-power flasher circuit showTi in Fig. 17. That circuit is similar to the one described above, except that the short Is removed from between pins 1 and 8, causing the capaci tor to charge via 9 Icilohms of in- ternal IC resistance (R4 + R5). The IC then operates with an in- creased duty cycle, and reduced average current is drawn. That circuit has a typical current drain of 0.32 miUiamps. A circuit similar to that of Fig, 17 can be designed for use with a 3-volt power supply. For 3-volt op- eration, the timing capacitor val- ue should be increased to 270 ^xF for approximately the same flash 5 6 cr 54 FIG. 20— HtGH EFFfCIENCY LEO indicator gives seemingly "continuous" operation from 1.5 volts. The current drain Is 4 miNi- amps. R2 R1 LED! cc B l7 [6 IT 2 13 H + cc RASHING fREQllEHCV,Hi CI m 1 R2 RANGE BV 2.0 400jiF tK 1.5K 5-25V 15V lOO^F 3,9K IK 13 -50V lOOV 17 iaO|aF 43K IW IK S5-2€0V RG. 21— THIS WAR KING FLASHER CAN OPERATE withm 3 voltage range of 5 to 200 volts according to capacitor and resistor vafues specified in the table. rate of 1 Hz. The average drain current for that circuit is 0.77 milliamps, which is more than twice the drain current of the L5- volt flashing circuit. Another variation of the L5- voit flasher shown in Fig. 18 oper- ates at a frequency of 2,6 Hz, In that circuit, the internal timing resistors are shunted by an exter- nal 1-klIohm resistor: the charg- ing time constant is reduced, the duty cycle is decreased and the average current drain rises to L2 milliamps. The circuit gives a far more noticeable flasher indica- tion than the lliree previous cir- cuits, but at the expense of a much higher current drain. If you enjoy experimenting with circuits, you can build the variable-rate flasher shown In Fig, 19. The flashing rate is varia- lumlnation and has a rather modest battery drain of al>out 4 milHamps. All of the LED flasher circuits we have discussed in Figures 16 througli 20 are intended for oper- ation from 1.5- or 3-volt supplies. The LM3909 can also be used with much higher supply volt- ages, ranging from 5-200 volts DC. The internal 6,5-voU Zener diode, wired between pins 2 and 4 of the IC, regulates the voltage between the LED cathode and ground. Those circuit configura- tions can be made with a mini- mum number of external compo- nents, as shown in the schematic of Fig. 21. As a final circuit suggestion, you can built a useful flashlight- finder shown in Fig. 22, The LM3909, 200-plF timing capaci- SLIDE SWITCH f^ LM3909 m , LE01 SHORT PINS . 1 km BFOR SIKGLECtU LIGHTS TRAHaUCEHT CAP RING CONTACT ON BULB ASSEMBLY FLASHING LED LOCATES FLASHLIGHT IN TOTAL DARKNESS RG. 22— A SIMPLE FLASHUGHT RNDER; THE capacitor and LED are installed Inside a translucent cap Tnounted on the end of the battery. ble from zero lo 20 Hz via potenii- omeler R4. Resistors Rl and R2 are used to stabilize tlic duty cy- cle of the circuit and maintain a fairly steady apparent brlgliiness level as the flashing rate is varied. The Fig. 20 circuit is designed to give apparently continuous il* lumination of the LED when powered from a L5-vo!t cell. The circuit operates as a 2-itHz square- wave ^|enerator: resistors Rl and R2 are used to approxi- mately equalize the on and off times of the generator. The cir- cuit gives a fairly dim LED iU lor and LED are installed inside a translucent cap mounted on the end of the flashlighl. An insu- lated contact strip connects to the positive terminal of the bat- ten^ and passes through the case for connection to pin 5 of the IC. The negative terminal of the bat- leiy connects to pin 4 (ground) of the IC. If a single -cell lighl is used, short pins I and B, Draw- ing current through the lamp fil- ament simplifies wiring and causes negligible power loss since the resistance of a cold bulb is less than 2 ohms. R-E Plug a Friend into this Christmas ... and §ave $19AS: Tliis Christmas give an electrifying gift plug a friend into Radio-Electronics and brighten his whole new year! 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Funds * ******************** REM** A0CTEMP.BAS - V910629 * REM** AOC0804 A/D IC & 2S2222 Temp Probe * P£|U|****A«*« It***** ft ***************** ******* 1 CLS ; DEFINT A, X; OEF SEG ^ 64 2 OPEN "TEMP, DAT- FOB INPUT AS 1 3 INPUT #1, add,lowvoit, lowvai, hi volt, hlval 4 CLOSE #1: OUT ADD +3, 145 I^£3t{** ******* ******* UP SCREEN ********************* 5 LOCATE 1, 23: PRINT "PcTEMP TEMPERATURE MEASURIKG SYSTEM" 6 LOCATE 2, I; PRINT STRINGS{79, 220): LOCATE fl, 32: PRINT STRINGS (1$, 220) 7 FOR 1 = 9 TO 16; LOCATE i, 32: PRINT CHR3(219); SPACE$C141: CHRS(219): NEXT 8 LOCATE 12, 33: PRINT STRING$(14, 220): LOCATE 16, 33: PRINT STBINGS{14, 220) REM**************** SAMPLING LOOP ********************* 9 again: 10 OUT add +2, 0: OUT add +2, 1: REM: Take A Sample 11 % = iNF(add): v - Jt * 5 / 255 12 cent=hival - * (hival - lowvalj / loifvolt) : f aren ^ 1,8 * INT(cent) + 32 13 LOCATE 4, 33; PRINT USING "Output • f .t*f v"; v 14 LOCATE 10, 37: PRINT USING cent; : PRINT CHRS(248); *C" 15 LOCATE 14, 37: PRINT USING feren; ; print chrS(248); "F* 16 FOR i - 1 TO 500: NEXT 17 IF INKEYS » CHRS(27) THEN END ELSE GOTO again Calibration First create the data file (TEMRDAT) with nominal values for port address, voitages, and temperatures (640. 4.K 0, 0, 1001: well fine-tune those values momentarily. Then run the pro- gram to initialize the PC 10 card. Next, connect the ADC circuit to the PC lO card, plug the probe into Jl, and place the lip of the probe against a piece of ice. Using a digital voltmeter on a low range, measure the voltage across the tip and ring of the plug. Record the temperature (0°C) and the resultant voltage. Pour some boiling water in a st>Tofoam cup, place the probe in the water, and repeat the process, recording both temperature (iOC'C) and voltage. Use the two voltage values to determine the temperature coefficient of your probe. For instance, if the' OX reading were 552 mV and the lOOX reading were 342 mV. the temperature coefficient would be (0. 342-0, 552)/(100} - Prepare a lOK potentiometer as showTi in Fig. 3-b. At this point, the ADC board should be con- nected to the PC 10, the 9-volt batteries (or other power source) should be connected, and the BASIC program should be run- ning. Connect a DVM across Jl, set the calibration potentiometer so the value on the DVM equals the high value taken earlier, and adjust R12 for 0,000 volts, as shown on the PC's screen. Then set the calibration potentiometer so the value on the DVM equals the low value, and adjust Rll for a value (as shown on the screen) between 4.0 and 4.5 volts. The actual value doesn't matter, just the difference between the high and low values. Check the high reading setting gj again to make sure it is still 0,0 ^ volts, and recalibrale if neces- sary. Go back and forth between g the two readings several times. Now enter the correct values I into TEMRDAT. Make sure the I file is stored in the same sub- u directory as the program, m Now you re ready to use the probe. Just place it against the ^ item to be measured, and hold it there until you get a steady tem- 62 perature reading. LISTING 2 IF CENT < 10,5 THEN OUT 1 tF CENT > 10-5 THEN OUT ADD+l, 0 LISTING 4 OPEN "READ1KG.DAT" FOR INPUT AS 1 00 WHILE NOT EOF{ I y INPUT ni, V: FRIHT V LOOP CLOSE: END Alternate ranging It is possible to adjust the cir- cuitry and the computer program to any temperature range you de- sire. Just recalibrate the circuit and adjust the constants in TEMRDAT For example, assume you want to measure tempera- tures between — SS'^F and + 104T, First, determine the tempera- ture coefficient as described above. Next, convert the desired temperature range from ""F to "^C using the formula C = 5/9 X (F- 32), In our example, +104T is 40'C, and ™35T Is -37.2°a Then calculate the drop at those two temperatures using the fol- lowing formula* Vd - + (T X TC) where is the voltage drop at OX, T is' the temperature in X. and TC is the temperature coeffi- cient. At 40'C, Vp = 600 mV + (40'^C X -2.1 mV/"C) = 600mV -84mV = 516mV, At -37,2'C, = 600 mV + (-35'C X -2,1 mVrC] = 600 mV + 78,17 mV = 678.17 mV, Now plug in the calibration po- tentiometer (shown in Fig.. 3-5), set It to the high-temperature drop (516 mV), and adjust R12 until the output is 0.000. Then set the potentiometer to the low- temperature drop (678 mV), and adjust Rll for a value between four and five volts. Last, insert the temperature values and the high- temperature output voltage into the data file. Now the circuit is fully calibrated for the new temperature range. Software modifications You could use the probe as a low- temperature detector. Con- nect a sensitive 5-volt relay to pins 9 ( + ) and 23 (gnd) of PI, If the temperature goes below a continued on page 82 UST1NG 3 4 CLOSE #1: OUT ADD + 3, 146: OFEK * READING. OAT" FOR OUTPUT AS 1 16 FOR i = 1 TO 500: NEXT: OUTFUT tl, V 17 IF INKEVS - CHBS(27) THEN CLOSE: END ELSE GOTO again 1991 ANNUAL INDEX BEctrnnscs* Volume 62 1991 Annual Index Radio-Electronics Volume 62 Abbreviations: (ARE) Ask R-E; (AUD) Audio Update; (C) Construction; (CC) Computer Connections; (CD) Compyter Digest; (D) Department; (DB) Drawing Board; (ER) Equipment Reports; (HH) Hardware Hacker; (LTR) Letters; (VN) Video News; (WN) What's News m^Do^ P^Manmm (ARE] Nov 12 874X Pto^anvw (EslyHC) HtcSi Mm 71 PostSoijt Caitndge {Hoft7man)(CC) Hw 84 Type Manager (HoitifnAfi)(CC) M 78 AiternafDrs as Slappar Molon FGCA(3p(W99NcNCod«(S«]nft^ Ape 77 American Hentage El«ctn3fic Dictionafy, HDu^iton liMt^ (HoiczmanKCC^ Jul 77 Mq^ Th« FnantSy (HoiiinanHCC) Aug 61 Afnpifier Design, EfSDaxy wd (KlanKAU) D*c 7S Anakig Scopes (O NeaO Nov 43 AnaJog-ko-Pigiial and Dig£aHo-An^ Comwiaf^ (BigvKMf j Jul 53 Anaty^ 2 Dm Um MonitDr, Data Contiqt^ Feb 20 AnaTy^ct THO (KeidefKC) Dec 47 Answertrtg a Lonta ci RfOf©sl; Trafl&toT Functiofis Part 1 1 tKl«Jn)( AUD) Mar 74 App(« Disk fARE^ Hb 12 Artjsolt^ LANtEistic Two-StHt>5n A£'2 Ethernel Slartor KiL (Holu ma/i ] (C C) Mar 84 ASK R'i (D) Hb 12,Mar 1 2 Ap r }2, Wiy t2, (LET ) Aug 1 4 Ju n B Aug B.^p 12,0ct B Nov 12,D«c 12 Assodalion Book Resources (L arvcaaiof ) ( H H ) Jun 6S Asymetrix Corp s ToolBfid Band Shortwave Re<»^vr {ER) Ssp IB Simp4c FM TfansrniHcr (Mcllt)n)(C) Notf 84 Speai0C1 14, May 72 Jun 72 Jul 74 ^ug BG.S«p 74 Oct iZ,Nov »i.Dec 7t Aufo AmpiAefs: Do TTw Sound DSfaiwit? Apr 60^LO)Oct u BoAxi Sotfvt Tttf: Fart I Jar) 80 ^RgrtH F««]£t Ekstortipn f^imei^ A; f^i Jun 73 F^2 Jut 74 Emoeocy and Anyiiif Deaao Dec 78 FiAffsBoducte Sep 74 JavanrTtK&iQllAinotinAuttoCdbnua HiayTZ 0£M.Cystecjillodals,andRMaUtiib NQva6 PtesefcM Futute tape Canndaes. The Aug 60 Reader LaOBim^ Sonw Bouquets and Bridibats OctBl Answering a Lfiflar d F^Diesi Ilar74 AiAmiottve CnarQing Sysierm {GfcssblanHDOl Dec 75 B Bakeftzing and Laminactng (Lanca^ief HHH] Sep 67 Battery Saila Owm (AR^) JUfl B^Oct 14 Ttehnotooy (Dewey) Jmi 45 IbdL 8uld the (EadyKQ Dec 53 Bmat^ Basici iSuner) Oct 5t,(L£T}Oec 14 Blmtoig Blocks (ARE) Nov 12 Boston Sound, Tbt; Rail I iKtetfiKAUOi ^ 30 Pan It (Kktin){AUD) Fe^ B1 Buck>t>atls and CGO (Lancaster^rHH) Aug 6d BUILD (See also CONSTRUOHON) Ule Sallofy Tool ( Eady ) [Q Dec S3 the MicroFiruilyziJf [ fAtga ) (C ) Sep 47 a Ntigarivo ^on aonijraJOf {Ctinjti)(C) Jan 4l,Fe& 55 R E s CaEl ■ Alert ( Krcu edt & Plant j(C) Oct 60 Your Own E!e<:triocarrfk3gmpti ( Roberts) Jul 31, Aug 44 Your Own Macinlosti-Compialibie Computf^r(Coiby 1 1 C) Jar» 31,(LET)May 1 4 (LET)Afif 13.(LFT)Ag9 14 Buvor^ GukSe to Digital Storago Oscilloscopes (Ptintlaa) Nov 31 Cable ID (ARE! Dec 12 TracoffARE) May 12 Calt-Afort. Buikl R^El (lOeuier & P^)(C) t:k:t 60 CaJier I D (Lancastet)(HH} Aug 69 Case and Endosurw Rosi>uro0$ (l.^ux^lcrr)(t^ Nov 78 Changing Face dl SaStf bite TV (Mov 1^} (LOIM 17 Cheai^ VtaiWe Lasers, arid More %u- Om MvaniDsh-Compati^ CofTfMler iCdbfHQ Jan 31 JLET>Uay 14 (LOTApr tsiLETlAug 14 OaMContrdtf Anafysra DtfaUneMbrvtorfER) Feb 20 I^gisal l*.iriTn<>f PC-Based. G^50aciatePCM)MM(CR) Nov 22 D(UMTe«ar(^t^Kn May33 Eip e rinie fl ii f ^ Wth PC-Based Equipinent (BartareAoHO May 57^ 4A^J S3 Lmc AnatAQT fRobidnn A DnvtrocaH C) Jul 47 PC-to-TV Conwerlar (Slswis fiC 3 Oct 33 RS'232 TefnviailAxvtor ^ A;*Tnch}( C) Aug 30 Sharp ModidPC^€500RK*elCorTipuJer(EF]) Aug 22 Turn ^itKtf PC Into « Unnwsal Ftequency Counter (Grasty A SchutzHO Fib3f7jlar43 Vk>eo Capture on the Cheap> (Tcmv^HC) Dec 37 COUmiTf R COHNECnOftS (HoftznuiiMD) Jan 04 Feb7B,l^84 Apt SS.May 77,Jun 60 Jut 77.Aug ei,Sep75 Oct94,Now 92.Dec84 1fi§1 R e ti wpec tt ^ Dec 84 Evolution alStandarda.lh« AprSS FrWKty Arnga, The Aug 61 HN»OfY in 6>e MiMu Oct»4 M&dSS50 Sep 75 NMrBegkmingfcjrMiCQlyfnn. A Jid77 Npw ^^ t^Jr^im Cofffig^ indusoy. A Hw 92 Some Pndtoilons lor PC^ to Oo^ne During ihe Next Decade Jan 844Ej^T)Apr 13 Video Sundardi May 77 Runs (and Ptoastires) (KottzmwiKCC) feb 76 micri Jun 80 CONSTnUCnON «74X Pyognmmer (Eody) KovTt AudKt gww plyl wlMf GenerMor (WMftamakcr) F»& 43.Mar 55 Butid the Batlory Tool (Eady) Dec 53 ihQ Microonalyzer | Miga) Sep 47 a I^Qgativi» Ion Generotor (Cansti) Jan 41 R€¥ CaJI' Aiert (Kn^tilor £ Piii n t) Oct 60 Ybur Own E]oclrocardii>gfUp+i (Roberts) Jul 3l,Aug 44 Vbur Own Mndntosh Compaiibla Ci EZ ShOftwvw Recener (Kieuter) Jan 56 Turn Your PC mio a Unmtti Frequency GounM^ (Grasty & Senium Feb 37,lfaf 43 13m Vbu T i i e p ho nea m a I Syttem (PObnierie) Hoy 44 Dec 37 Apr4SJIarS3 OCI39 Aug 61 May 41 Jun 54 Capita on tie Cha«p1 r^inert TeleptowtColT^) ^loN jHoctt-Uiiaf (Wiedafl Wlage DoitiB (HiMw) Coritnous*^^ G a neca lO f (PlaMKO Convcneri. VSep IS Fuse {P$liuiel1isHC) Dec 63 Tuning Diodes, let's tjook al tL2ncaster}(HHj Jun 65 E56CtrOniCs VAsrhtjenchn IniaractrvQ Ima^ Tcchnotogtes' fHo?izm3n)fCC) Jul 77 ELF Gaussmetor Magnetic Reld Meter (WealtC) Apr 33 £nongy Consufrptiori Morntof {Brufol(C) Dec 3t EQUIPMErrr reports (OJ Jan 12,Feb 20,Mar 22 Apr 18, Jun 22. Jul 20 Aug a2,Sep iflnOct 22 Nov 22, Dec 22 Data Contrdsf Analyst 2 Data Line Monitor Feb 20 Fluke ModE3l 1£ Digital MuHimoter Dec 22 Model 45 Dual Display MuHirnoter Mar 22 Model 79 DMM Jul 20 Gk>bai SpeoialtiQS PCI DMM PC-Based Mudimeter Nov 22 Profolab Jan 12 Hewleti Packer 0 &460tA Portable Digital Oscilloscope Apr 18 HS3S Heavy Duly Stich" Style Multirrieter Jun 22 n L Drake R-8 WfofLd Bjnd EtKMt^ave Receiver Sep 18 Sharp ModQi PC-E500 Po<^et Computer Aug 22 Dmis T Conversiw Factors Unit Ccnverskm Solt'A^re Oct 22 Ewry Test Bench Ne^s a Good Power Supply (Gr0S5btatl)(DB) Mar 77 EvoFuHon of Standards, The {Holt2mafi)(CC) Apr 85 Ex penmen ti ng ^^Vith PC-Sased Test Eguiprr^ent (Barbareito}(C) May 57, Jun 48. Jul 53 Expefimer^ts \n Voice Rocogmlion (Cooperjf C) Apr 49 Ferroelectric IC^: Chips That Ftemember (Byers) Mir 63 FvfslA|>ps. hDC Computet Corp. (Ho5lznrjan){CC) Feb 78 FLashijghi Battery SuppHes I Lanca3ler){WH } Oct 72 Fluke Model 12 DigitaJ Multirmter (ER) Dec 22 Model 45 Du^l Display Muttimeter (ER) Mar 22 Model 79 DMM (ER) Jul 20 Ftyback Squeal (ARE) Apr 1 Z FM Stereo Standards ( Lancaster) (HH) Dec 69 Transmitior. Simple {Met[on)(C) Nov 64 Focused K-Ray Breakthrough, and More (Lanca5ter)[HH} Aug 89 Fractals and Chaos Update {Lanca3ler)i[HH} Dec 69 Frequency Counler, Universal, Turn You r PC Into a (G rasty a Schulz) [C } Fab 37 Friendly Amiga. Thu (Holi2nian}(CC) Aug 81 Frugalvision Image Capture Board Video Capture on the Cheap! (Toner) (C) Dec 37 Fuel Cells iHubscher) Jun 81^LET}Dec t4 Fulufe Products (Ktein)(AUDj Svp 74 Global Speclelbes PCI DMM PC-Based Mutlirtietef (ERJ Rroiolah (ER) Nov 22 Jan 12 H Ham Radio Cal I Alorl , QuiEd R ■ E S (Kreuter & Plant) (C ) Oct tJO HARDWAREHACKER(Lancaster}{D) Jan6fl.Feb71 Apr 71, May 65, Jun 65 Jul 68, Aug G9,Sep 87 Oct72,Nov 78,Dec69 Cheap VjSJbio Lasers, and More Feb 71 CokJ Fusion IJpdaie. and More Jan 68 Curve Fitting Fuzzy Data Oct 72 Driving Inductive Loads, arid More Sep 67 EJectnc DOflTag Coolest, and More Nov 7B Focused X-Ray Breakthrtxigh. and Mofl& Aug 69 Let s Look at Etec(Ton>c Tunjng Diodes Jirn 65 New Hackat>3e Projeci Ideas, and More Apr 714LET)Jyl % Standards Resource InformaJton, and More Dec 69 Toner Carlrk^ Retoading, More On May 65.(LEinAug 14 Understanding Translonns. and More Jul 66 Heart Monitor, Ooppler-Ultrasoynd [Jaffe)(C) Nov 49 Hercules Graphics Station Card fHoHzmanSiCC) May 77 Hewlett Packard 5460TA Porioble Digital Oscilioscope ^ER) Apr 18 High-Energy Resources ( Lancaster) (HH) Oct 72 History rn the Making tHoltzman)fCC) Oct 94 Home Iniorcom System r Use Your Telephones as a (PoiimeneJIC) May 44 Home-Energy Monitoring (Uncasier)fHH) Dec 6S Hot Troubtesbooting Trps 1 Phelps) Feb 61 Houghton Mifflin's American Heritage Dictionary (Ho}Umanj(CC) Jul 77 HS25 Heavy Duty "Slick" Styte Multimeier (ER) Jun 22 Dec 12 Jun 80 IBM Compalibflitv f ARE) XGA Adapter |Holtzman)(CC) Induction Motor Speed ConjroJs (Lancaster){HH) Feb 71 Infrared Peopte Detectors (Lancaster) [ H H ) Apr 71 "In-Package" Battery Tosiiers (Lar.caster)(HH) Apr 71 Inside Markeiing InTormation for the Audio Consumer (Kloin)(AUD) Nov 66 Switching Power Supplies (Triesley) Apt 57iMay 49 tntef S052 (ARE) Oct 8 Interactive Image Tecbnoi'ogios' EtectroofCS Iwikbench ( Ho]tzman)(CC) J u 1 77 Intercom. Home System Use Your Telephones as a {Poi mene)(C) May 44 intuitive Look At Electromagnetic Theory. An ( Rice) Aug 65.Sep 57.0ct 53,Nov 64, D«c 60 Japan . Ttie Evolution ol an Audio Coiossus {Ktein){AUD) Keyboard Tracer {ARE) J 1 ^UD) K May 72 May \2 Laser Mrtter, Poor Mans ( Renion)(G| Apr 1 7 LEDTiotiblesfAREJ Sep 12 Let's Add an Audtbie indicator to Our Logsc Probe (Gnossblait)( DB) Jun 74 Butld an Osciltoscope f {G rosstilalt)(DB) Oct ZS Look at Electronic Tuning Diodes (Lan<:as1or)(HH) Jun 65 Lm-ERSfD) Jan 9,F«b IZ.Mar 16 Apr 13, May 14, Jun 74 Jul 6.Aug t4,Sep 16 Oci 14,Nov 16, Dec 14 Lino Power From t2 Volts (CuthbertJtC) Apr 43 Logic Analyzer I RobidooK &. Dmi^ca) ( C) Jun 31t Ju 1 47 the Micro Won itor (Cooke) (C ) Oct 67^Nov 67 Logic Pnsbe A Simple. Inexpensive (Grossbtatl ) [ H H ) May 75 Audible PC Board For Our (Gro35blaM)(OB) Aug 77 Lel^ Add an Audible Indicator to (GrQssbla|t)(D6) Jurt74 Long-Play;ng i^ecorder. A (ARE) Mftr 12 M Apr 71 Mac^ne-Shop Resources (Lancastet)(HH) Macintosh-Compatible Computer, Buhtd Vcur Own ^Colby ) ( G) Jan 31 ,(LET1 my 14 fLET}Apr13,)LET)Aug14 Magnetic FieW Meter lMetE)tC) Apr 33,tLET>Jul a,(LET)Sep 16 Making Connections (Holt2man)(CC) Mar 84 M icro Monitor {Cooke){C) Oct 67. Nov 67 Microanalyzer, Build the (Miga)(C) Sep 47 M icrografx Designer 2,0 { Hoitz rtian)(CC) J u 1 77 Microsoft MS- DOS 5.0 (Hottzman) f CC ) Sep 75 Windows 30iHoltiman5(CC) Jar»64.Feb7a Wndows 3,1 [ Ho]tzman){CCj J un M Micnorta^e-Oven Tester Butki I he Micfoanalyzer {Miga)(C) Sep 47 Microwave Resources (Lancaster)(HH) May 65 More On AM Radto ( Dec 1990) ( Lrr}Feb 17 J'^OreFonls. MioDLogic (HottzrTtan)tCC) F«b 78 Moforcyde Rebuikl (ARE) Aug S MS-DOS 5.0 (Holt£men)(CC) Sep 75 Multilayer Keyboard (ARE) Jun 8 ,(LET}Se|i 16 Multimeter, Fieidpsece HS25 *Stick" Style (ER) Jun 22 iMmic on Hoki (Hausm^)(C) Nov 58 N Jan 41 ,Feb 65 Jul 77 FCC Approves No-Code (Stone) R£9^u1alions (Lancaster)(HH) Apr 27 Oct 72 LANtastic Two-Staiion AE-2 Ethernet Starter KfI, ArttsoltS (HotEvEmark)(CC) Mar 64 Negati^ve Ion Generator Build a (Carfsti)(C) Now Begin ning lor this Column, A {Holl2man)(CC) New HackabSe Project IdeaSn and Moro (Lancaster)(HH) Apr Tt NEW UT (D) Jan 2a.F^avO RtKieiwr^ Tuno in ih^ \^tof1d Wiiti (KfuutefJlC) ^.L Drake H -S World Band &hort««ve Recetver (E^ I Stp 1 B ^3def LfJtlEKs: Some BququiMi} and BnckbOfto (Klaln)(AUP> Od 82 ^odtX . Siepper hWof ^ EftdyJ(C} Apr 63 ^232 TormsiBl'MDnjlW {Av7ttcfi)(C) Aug 5Q >3te Oiargiog (ARE) Jun B.Oct U Scope. PU&ng a r4«w On* to Wark (Ranwez^ Jan SO ienigwjuciy tiemofka (Stpeto*> llir6t R&232 T«cnin^lykinior {ArtttOi^j Atig 50 Hoi TiDubtoshoOttfig Tipa (Pheta^ Feb 61 PimingaNewSoopoioVUQrk(IMi«J J»n50 i]^McxM PC-E£oaR)dbetCornptrfar(EITt Aug 32 Jin 56 Sepia R-E'a EZ. Time in the Wortd (Kr^utef KC) RL Onik« R^ World Band |ER) SJinple bui EHoctive Tost Equiprrwnit tGfos&biaciHDBj F*^ TrartsfTrti^ tWe^)fC) Ineipenaiw Lege ftotte- A ^GlDSSb^«li{^#^^ Ape 71 HovS4 ||py75 Geriefatcr (ARE) Oct 6 SynlhesjZGf; Otgiial {SwHll(0 Oct 43 iingJfr-Chonnol Filler (ARE) Aug B 5towflf Rocording (ARE) Ocl S >MPTE "n™ Code SlandJirds tUuxasl&r)(HHj Nov 71 SOFTWARE 87^X pTDgrflfTinw lEady)(C) Hcv T1 Adobo Pto^tScfipl Canridgii (Holtzman)(CC) Mar 84 Type Mariagcr (H£5[l;iniir^}(CX;) Feb 78 American Hcfitago Eloctromc Dictionary. Houghton M^Wm^ (l4ortjma/5)(CG^ Jul 77 DossTalk tar WLnt^^ . OCA (Ho(mnan)(CC) Beb 78 Coref Draw lHoltEinart)(CC) Feb 78 Elffl^jonics WbrWsencti, Interadtve Imaoe Technotog^^ (Hoft^manilCC) Jul 77 FtfUApps, hoc Compulflf Cdfpi (Hoftzmar^lfCC) Feb 78 MicrogrA Desigrw Z,0 {Hoezman)(CC) Jul 77 Mcrtnd^ MS^DOS 50 (HoltlwiKCC) Sep 75 Wrtdnn 3.0 1ltoltzmv)}^CC) J>n 76 VUM?HS 3,1 fHoltzmar^HCC) Jun 60 Mof^Fonts, MkraLogk: 1H0ttzitiarr}{0C) Feti 78 Pizazz Plu$, Appi(3&oriTtehnjques^4iiBnTtBn)(CGi WmbTB Seitmen Soluiion (ARE} Sap 12 IddBoGk 1 0. A$ynietrn Cdrp^ (HdltenanKCC) i«ti 76 Wn6emi BjOon [Hc3ltz7n^](CC) 76 Jun 60 Jun 60 (and Pleasues) rHoltzmanKCC) 76 3 0. yiGOM (HoMzmaiKCC) Jan 84M 78 Unts Y Convenioei Eidors VrrH Ctjnmtim Bcittm lER) Sotar Energy efwkVsough tL3nc3Sief)(>W) Soid Sttto Doi (pylmdiHC) Soma (^wleioni lor PC% to Ccffiw Du%ig tfM Nioct (HoUzmanKCC) Speiakar C^t^es^ " * Improve V^w A«io? (Honeycun) Fab 50 Aug 55.4LET)Oec 14 Oct 22 Nov 76 Sep 33 Jan 64 SpeaXe* Ptotocfof {\feugtit)(C) Specirum Arwiyf (K (Oot^efii^in & CanloneltC) Star>dardi Resource Intormatfort. and More (LancasrerKHH) Tho Ewjiufjon ol (Holt2mam)(CC) Vidflo (HoltznTan)lCC) SK^pper-K^orof Robot (Eady)(C) Simpio but Efleciive Te«t Equ^iment (GmssblaliHOBI Apr 76 Spadfwn Artatyz^ (Ddberstein a Cardone)(C) Aug Sl^Bep 40 THO Analyzer i Hei^m Dec 47 Tbrn ^ftiur PC lito a Uhwfsal f^agusncy Counter ((irasty & SdtutiKC) Feb 37ilar 43 THO Anafyzer {Keidd)(C} Dec 47 Tonof Caftridge ReloaiinL Men On (L^icsterKHH) liay 65 TbCai Harriaric DEsmon (ARE) Dac12 Trarraier Ft^icijons Pan II: Answfifirig a Loftier o( PttMASi (IQflirtKAUO) Mar 74 Trarism^ Simple FM (hMnKC) Nov 64 TrfMjble«)0dttngTfia.HgtrPheip8) FebSI Tm m tie vybrid wah EZ Shoftmove Recenw fKrHAet HCf Jan 56.(LET)Ocl 14 Titfn Ybi^ PC Into a UnrwcfsaJ Frequency Caumer (Grasty 6 SchMUllC) Ht> Jf.Uti 43 Aug 33,5«p 40 Dec 69 Apr 85 May 77 Apr 63 U Switching Powof Supplies. Ins^do (Tnolley) May 49tApf 57 Jan 68 Jul 68 Oct 22 Oct 60 Aug 59 NiwSB Sap 60 Aug 69 Tape Canr idges. The Pssx. FVi^sent, and Future of (K$ejn)rAUD} Aug 60 Technical Literature ( Larcai^ef )(HH j Jan S8«Fab 71 Apr 71^ «9,0ct 71 Tateoommuncations F^nonal Oommymcafaons Networtts tMe«w9) May 61 TELEPHONE Butkl R E's a^ A}^ IKreuief 6 Banl)(C) CaJ^ ID {Larcasler){^) iJkjs^ on hokl (Hausn^Hpl Phone Senfru The (CooperKQ T Btop h on t Wowwaon (Ureaaaf)ff#0 HPme tmaroom System (Foifnm)(C) May 44 Videci 'Mephone (CcA^C) Mar 45 TvTTvriaiMMCMr ^23Z (A»tiich)(C) Aug 50 Ooii. Soid State IMmdKC) Sep S3 Coils (Lanca^arKm^ Oct 73 TEST EOUlPMENr Analog Soppsa (Osteal) Nov 43 Audio SMMprWarker Gonerauy (WamamalcerHC) Fab 43.liar SS Build the Miaptti^er (MigaKC) Sap 47 Cotaf Bar Gacwater (GoiAlS(Q Jul 41 Data Contitifar Analyst 2 Data lino Monitor (ER) Feb 20 D^ital StrwMmo Synthesizer (Swttt)EC) Oct 43 Dtgitat StoraciD OscUbscopes, A Buyer's yuldo U> {Prentiss} Nov 31 DRm Tesifl r i Huftt) [Q May 33 Eloctionic Fuso (P@truzelfis|fO) Dec 63 Ej(pedrnentir>g With PC-Basod Test Equrpmeni (BarbarelloKC) Fluke Modol 12 Dk^ital Multim&t&r (ER) Doc 72 Mo6q I -1 G □ util Display Mullirmter ( ER) Maf 22 Moooi79DMVliEn) Jul 20 Global SpocMftitM>s PCt OMM PC-Eased MjfmuHet (ER| Nov n PralolaO (ER) Jan 12 Hawied F^Kiiard 546CnA POflablo Digital QsciBoscope (ER \ Apr 16 Hot Tr?uble$r)ooiing Tips ^PtxFips} Fab 61 Letlft Bu^ an OscJoscope' rGro$sbiMi)CDB) Ocl 65 U»>c Anaiyzar (Rotxlouji & DntitrocaKC) Jun 3Uul 4? Mono lAonior (OookeXC) Od 67.Nov 67 PU»eMM(^WlXQ May 41 PUamgaNawSoopetoWbftCRamiiBi} Jan 50 UfKltfStandIng Doobels (Lancast43r)(HH] Triinstorms^ arxJ More (Lancaster)(HH) Units 4 Conversion Faclors Unit Conversion SoFTwArti |ER) UnivOr^E Frequericy Countor. Turn Vbur PC trtto a (Grii^y & 3chull)(C) Feb 37.«ar 43 Unusual Newsletlers (Lianca$^1&r)(HKl Jun 65 Use Your Tefephorws aa a Horrw Intorcorn System (PobmiirwHC) May 444LET)Hov 16 V'^ Convecfers fTneilay) Vantm Futsb^nf Windows EsStion (Ho»trmaf^)tCC) VHF Rcsoufces |Lanc2Slef)4HH) VIDEO (See ^so VIDEO NEWS) Coior Bar GenefOKir (GcmMHQ PC4D-7V Conwiar (SMnsMQ Caotwe on tie Cheapt (IbnetKQ Compression Secrats {tartcastef ){HH I Cfosshaldi Generator rLancasteriCHH) Standards [Hotaman)(CC} Sync (ARE) TeHptione (Ooi>y)fC j Tima OKtes (lanMerHHH) VE»EO NEWS a^chttibmchMD) Jun 54 Feb 78 May 65 Vocat EHectsl^ixer (WMei )(C} Wjtce Reoogrmidn. Ejiperments in (CooperHQ VOttage DcuCiler {HubschorKQ lo-Froquency ConvorrefS (Tnottey) W May 57 Jun 46 Jut 53 WHAFS NEWS (0) Vtevotol Bfeakthoug^ts (Uncasler KHH) Wholv&ate Surplus Sources rLancaster)(HH) Wig-W^ Ctfaat? (ARE) 1MB "B&astie" SpeaJtef Catiies itrtptcw fair Audto'> (HomjycuO) Wind-Speed Head (ARE) Apr 1 2 (ARE) Window* Runs rand PlQ33ue$i (Botzzman>{CC) 30. ItenscA (HottzmanKCC) 3.1 (HoBzmar^OQ meh (HoQzmanKCCt Jul 41 Oct 33 Dec 37 Jut 66 Jul 68 May 77 Feb 12 Mar33J^4S Oac^ Jan6.Feb 6.Maf 6 Apr 5.Ma¥ S,Jun 6 Jul 6.Aug 6rSep 6 Oct 64NOV 6, 0«c 6 t3ct39 Apr4S Aug 61 Jun 54 Jan 4,Feb 4.Mar 4 Apr 4, May 4 Jun 4 Jul 4,Aug 4^Sep 4 Oct4,Nov S,DTpe. SPST toggle switch SI is used as the answer switch and is mounted next to LEDl, the "power on" indicator. Cut the leads long enough to reach the front panel without too much ex- cess. Volume control R20 has Us attached switch, S2, wired in se- ries with the microphone ele- ment to provide a "mute** function* The mute setup works well because the low-impedance microphone circuit doesn't pick up interference when open. If the mute function is not needed. R20's switch can become the ANSWEE^ switch and you can elimi- nate toggle switch SI, Howeven the complete kit does include the toggle switch. FOIL PATTERN for the Speaker-Mate. In preparing the circuit board for the cabinet, leave the speaker leads long enough to attach the speaker on the top haif of cab- inet. We have found that a spare piece of perforated construction board makes an excellent drilling guide for making a neat speaker grille on top of the cabinet. Cut- ting out a notch on the cabinet rear for the modular telephone Jack fJl) and drilling a y2Mnch hole for access to the microphone gain potentiometer completes the cabinet back. Completion of the front panel is next. Figure 5 shows how we mounted the microphone. A %- inch inside-diameter rubber grommct was glued to the inside of the front panel behind the Inch microphone opening. You can use either hot-melt glue or RTV silicone. Insert the micro- phone element (with leads at- tached) Into the grommet so that it sits back jusl enough to not touch the front panel, but no more; a recessed element will give an echo sound we want to avoid. This step acoustically and me- chanically decouples the micro- phone from the speaker output, yet gives some directional effect* It will be glued in such a position in the grommet in just a minute. Note that an electrct microphone is polarity-sensitive: the pin that connects to the case of the micro- phone is ground* Finish up by wiring R20 and its switch S2, LEDL and SI. We found that prewiring these com- ponents first makes assembly easier. The final step is to fit the panel into the enclosure and glue LEDL the microphone, and the speaker in place with RTV sil- icon, making sure that the elec- tret element is positioned as mentioned before. Set the micro- phone gain potentiometer R15, to about halfway Figure 6 shows the completed Speaker-Mate pro- to^rpe. lasting and use For acoustical reasons, the proven approach to testing the unit is with the board mounted in a closed case. At an exlreme setting of microphone gain, the microphone may pick up the speaker output. This extreme continued on page 83 2.2K TELEPHONE LIME INPUT IPJ PARALLEL Wrm SPEAKER-MArt 100V AC INPUT OUTPUT TCM1S12B AC INPUT FILTER OSCR COMMON POO TEUKSDUCER PIG. 8--Y0U MAY WANT TO ADD a ringer to the Speaker-Mate, The tone ringer chip (103) monitors the telephone line for a ring signal of 15 to 66 Hz, 40 to 1S0 volts AC. Resistor R sets the warble and center frequency i with R at 150K, the warble Is approximately 10 Hz and the center frequency is 1250 Hz. HARDWARE HACKER VGA adapter for the Mac LC, computer monitors, flyback, shielding, and GPS navigation resources. DON LANCASTER I t seems 1 did miss an obvious source rn our recent Tes/a and High Energy Resources sidebar This is the Tes/a Soc/efy up in Cobra* do, who runs a great museum and now offers annual Tesia and nontradi- tional energy conferences. Their High Energy Enterprises division has lots of books and videotapes. These range the gamut from hard- to-find and genuinely useful research materials on down (way on down) through bunches of "Boy-a-whole- flock -of- them- f lew-over- that- timer* pseudoscience titles. On the other hand, if you are into antigravity. the 1000 miles per gallon carburetors, Russian weather control conspiracies. Reed motors, ail those pan galactic happy faces on Mars, or zero point scalar energy, these books and videos are definitely for you. This is most fascinating reading and watching, either way. Actually Til freely admit that I firmly now believe in one trilateral conspir- acy That's the one involving the first, second* and third laws of ther- modynamics. But that's just me. And if you want to prove me wrong, just show to me any simpfe and indepen- dently verifiable experiment that any- one can reliably duplicate. Some more info on wavelets: The Wavelets book offered by Jones and Barttett is at long last in print. And a major new tutorial just came out in the October t991 lEEE-SP Signal Pro- cesstng magazine on pages 14-38, Shietds and shietding These have been popular topics lately on our helpline, so perhaps tt is time to go over some fundamentals. You can shield something electronic either to keep objectJonsble signals from getting out or getting in. For instance, on any light dimmer, you might want to suppress the horrible AM radio interference caused by a triac suddenly turning on. On a low- level audio circuit, you might want to prevent power-line hum and noise from getting to you- If you do know ahead of time that you're going to have interfering noise or signals present, one very powerful technique is to change over to fully balanced circuits. They sense only the differences between their inputs, rather than any absolute values with respect to ground. Thus, any common mode interfering signals that bounce both inputs up and down together will automatically be re- jected. Or at least suppressed. Sev- eral fancy audio studios have even gone to totally balanced power lines to dramatically reduce their hum and noise problems. There are usually two paths that interference can travel One is with radiated energy, which can propagate directly through space to emit from or interact with your circuit. The other is conducted energy, which enters along your power connectors and in- put or output cables. Since separate tricks are needed to deal with any radiated or con- ducted energy step one is finding out which path is the one you will want to deal with first. The radtated energy interference will usually have two components. They are that "E" or electric Field, which largely concerns itself with in- duced voltages and that "H" or magnetic field, which creates indue* ed currents. Once again, you have to NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 know which field component you are going to suppress before you pick a pnDper method. Any old conductor should usually block an E field. One obvious hacker choice that works well are boxes built up out of double^sided printed-circuit board. See Fig. 1. But there are gotchas, At lower fre- quencies, there is the lack of a well- developed skin effect, which causes an E field to penetrate deeper into a conductor Thus, thicker shields are needed to suppress lower frequen- cies. Say 20 mils for an AM bmad* cast band use or 80 mils for the high ultrasonic frequencies. A shield can also act as a shorted turn to any nearby inductor, possibly lowering the Q and detuning. A slot or other continuity break can some- times help this pnDblem. While some small shield holes are often tolerable, any poor contacts are definitely not. A continuous solder bead or else !ots and tots of individual screws may be needed for really high shielding effectiveness. It's very important that unintended currents don*t ever run through any shields. Unwanted signal drops can often end up in series with your input signals, making things much worse rather than better. Which is also why you should keep all your digital and analog grounds separate. The H fields can be blocked by use of any strongly magnetic materials. These materials are said to have a very high penneabiHty^ The simplest g magnetic shield is a piece of scrap ^ sheet steel fn^m the air conditioning ^ shop or trailer hitch works. But things fS get messy in a hurry if you need lots 3J of magnetic attenuation. g Those special and fancy shielding m materials are optimum only in certain o thicknesses and over a specific fre- | quency range. Worse yet, some of 8 these cannot be cut or drilled without a complex reannealtng process. And 67 I c liJ 63 RG. 1— SIMPLE E'FIELD SHIELDS for ra- dfo-frequency hacker projects are easily built up from pieces of double-sided printed circuit board stock. too Strong of a magnetrc Field could saturate a shield, making it useless. To be effective, a magnetic shield should completely surnDund the vol- ume it is protecting, A good free booklet on all of the fundamentals of magnetic shielding is available homAmuneai, while other sources of custom shield matenals now include Advance Magnetics and Magnetic Shield Corp. Conducted interference can be best eliminated by some blocking fil- ter. These filters should freely pass NEW FROM DON LANCASTER HARDWARE HACKER STUFF Hardware Hacker Reprints ft or III 24.50 Midnight Engineering Reprints 16.50 Incrcdi&Ee Secret Money Machine 1&.S0 CMOS Cookbook 24.50 TTl cookbaok 24.50 Activo Filler Ccoi(t»ool( t9.50 MEcrO Cookbook vol 1 Qt II t9.50 LOftcuslor Classics Library 109.50 AppioWrllcr Cookbook 19.50 POSTSCRIPT STUFF Ask The Guru Reprints 1, 11 or 111 24.50 l& ser Wr I te r So c ro t s ( 1 le/Ma C/PC) 29. 5 0 PosrScrlpl Show & Tell 39.50 Intro to PostScript VMS Video 39.50 PostScript Beginner Stuff 39,50 Po s tSc r i p t Coo kbo ok ( Ado b*) 1 6 J 0 PostScript Ref. Manual 11 (Adobe) 20.50 PostScf ipt Program Design (Adob«} 22.50 Type I Font Format (Adobe} 15.50 LiserWrltef Reference (Apple} 19,50 Real World Postscript (Roth] 22,50 PostScript VESU3I Approacti (SmJtti) 22.50 Thinking In PostScript (Reid} 22.50 Un ds I PS Pgr mm g {H 0 1 tzga ng) 26^ Ttte Whole Works (^11 PostScript} 29350 BOOK-Ori-DEMAND STUFF Book-on -demand resource kit 39^50 Baker tztng lllm package 1fi.50 F R E E vol CE H E LPl tNE VISA/MC SYNERGETICS Box &09-BE Thatcher, AZ 85552. (602) 428-4073 GPS RESOURCES Ashtech 390 Potrero Avenue Sunnyvale. CA 94086 (800) 229-2400 CieCI-£ 301 ON FREE INFORMATION CARD Bancomm 6541 Via de! Oro San Jose. CA 95119 (408) 578-4161 CIRCLE 302 ON FREE JNFORMATION CARD GPS World RO, Box 10460 Eugene. OR 97440 (503) 343-1200 CIRCLE 303 ON FREE INFORMATION CARD Magellan Systems Corp. 960 Overland Court San Dimas, CA 91773 (818) 356-2363 CIRCLE 304 ON FREE INFORMATION CARD Magnavox 2829 Maricopa Street Torrance, CA 90503 (800) 421-5864 CIRCLH 3^ OH FREE INFORMATION CARD NASA Tech Briefs 41 East 42nd Streel Sle. 921 New York, NY 10017 (212) 490-3999 CIRCLE 306 ON FBEE INFORMATtON CARD Rockwell Commerciaf GPS RO. Box 568842 Dallas. TX 75356 (214) 996-5863 CIRCLE 307 ON FREE INFORMATION CARD Speleonics P.O. Box 5283 Bioomington, IN 47407 (812) 339-7305 CIRCLE 308 ON FREE INFORMATION CARD If /GPS Products RO. Box 869305, M/S 8449 Piano. TX 75086 (214) 575-4057 CIRCLE 309 ON FREE INFORMATION CARD Trimble Navigation 585 North Mary Avenue Sunnyvale. CA 94086 (800) TRI'MBLE CIRCLI 310 ON FREE INFORMAHON CARD the signals of interest, but present a high series innpedance and a low shunl impedance to all others. Murata-Erie is one good source. The ferrite bead is a remarkably cheap and super effective inter- FIG. 2— FERRITE BEAD interference sup- pressors are simpty slipped anto any con- ductor. The f errile beads behave as lossy and broadband higli-frequency transfor- mers. Multiple turns can also be used. ference suppressor. As Fig. 2 shows us, you simply hang them on a wire or else run a turn or two through them. Ferrite beads act as a broadband htgh- frequency lossy transformer There are various materials and sizes, again depending on frequency. Sources of ferrite beads include Fair- Rite. FerriShield. Ferroxcube, tntermark, and Siemens. One very little known ferrite bead gotcha: Do not ever cast a ferrite bead in epoxy or othenwise constrain it so it cannot move. The beads must be abie to physically change their size slightly, or else the performance will sharply degrade. Two trade journals that involve themselves with shields and shield- ing are Electronics Test and Compliance Engineering, Monitor fundamentals We sure do get a lot of computer* monitor and TV compatibility calls. Let's start off with the obvious: The performance and bandwidth of an ordinary TV or VCR using composite NTSC video is severely limited. That is why all the computer folks went to special RGB monitors in the first place. And that is why nearly all the computers are totally incompatible with ordinary television gear Yes . there now are all sorts of ways you can use your computer for real video editing or to record computer sciTeens on a VCR. But note that there is no way I know of that you can record plain old 80*coiumn text as composite video on your VCR. Or display it on any unmodified TV set. How does a monitor work? Inside is a cathode ray "picture tube" with one or mom guns that squirt lots of electrons at a phosphor semen. At 1 HORIZONTAL DEFLECTION YOKE HORIZONTAL FLYBACK DAMPER OUTPUT CAPACITOR DIODE H YOKE CURRENT FLYBACK VOLTAGE HORIZONTAL SWITCH DAMPER DIODE +V SUPPLY FUNCTION 1 off on off ] on 1 on off 1 on 1 off 1 sink source sink | source | FIG, 3— THE RECURRENT FLYBACK SWEEP on television sets and computer monitor displays Is extremely energy etftclent, but will only work over a VERY llmiled range of horizontal scan rates. any instants only one single dot ap- pears on the scneen. That dot gets moved around by the scanning pro- cess, and will get brightened and dim- med by rapidly setting its intensity at a video modulation rate. To build up the illusion of a full pic* ture. that scanned dot is moved rapidly and honzontaily from left to right ar^d more slowly vertically from the top to bottom. The decay charac- teristtcs of the phosphors selected and your human persistence of vision combine to create the illusion of a total picture. Television uses what is known as an interlaced scan. To build up a TV frame, the dot starts at the upper left and rapidly scans to the right and slowly on downward, painting every second scan line. When it gets to the bottom of this field, it goes back to the top and picks up what it mrssed, painting a second field. The normal field rate is usually 60 hertz for black and white or S9.94 hertz for color The NTSC (National Television Standards Committee) standard uses 512 (ines per frame, or 262.5 lines per field. That leads to standard horizontal scan rates of 1 5750 Hertz for black and white or 15735 Hertz for color. The two numbers end up slightly different to get all the rest of those color magrc numbers to pfop- er(y drop in place. DIGITAL VIDEO STABILIZER ELIMINATES ALL VIDEO COPYGUARDS While watching rent* a! movies, you wilJ notice annoying pe- riodic coJof darken' ing. color shift, unwanted Imes. flashing or jaggea edges. This is caused by the ccpy protection jammEng signals embedded in the video tape, such as Macrovision copy prelection* the oicrrAL vtoEo stabi- y^ER m COMPLETELY ELIWWATES ALL COPY PROTECTIONS AND JAM- MING SIGNALS AKD BRINGS YOl> CRYSTAL CtJEAR PJCTUFieS WARNING THEOlGfTAL VlO£0 STA- BiUZER IS INTENDED FOfl PRIVATE HOME USE ONLY. IT IS NOT IN- TENDED TO COPY RENT. AL MOVIES OR COPyRGHmO VIDEO TAPES THAT MAY DON- STTOITE COPYTONT IN- FraWGEMEhfr. 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NY 11580 CtRCLE tSl 014 FflEE INFORMATION CARD CABLE TV DESCRAMBLERS How You Can Save Money on Cable Rental Fees Bullet Proof WcSL Super Tri W Aui fw' JcTTDkl Super Tn-3i- $]09.9$.$79 Piiiii«ikTZfCl45^ %n.n~SJ9 E>^ Video Staii«Kr. i5W^SS9 USCablcMllkat Anyone's Price Advertised In this Magazine! 30 Day Money Back Guarantee FREE 20 pag* CiitJtlog Visa, M/C, COD or send moncj' order toc U^- Cable TV lac, DtpL 53S0I 4100 N. Powerllne Kd^ Bld^ F«S 1-800-772-6244 ext.53S0i For Our Record L llx midnip»t do bcn^ dedare unJer peoAfl^rcj^ uied « TV miciu wub prtTpo' luiJliorisifkn p£icablefcitcnlvidiui«Uwi. FEDERAL AND VAHKXJS V^TE lAWS PROVIDE FOR SUBSTAWnAL CRIMINAL AND OWL PENALTIES PQR UNAm-MORtZEO USE. Dale-, CIRCLE 192 ON FREE INFORMATION CARD NAMES AND NUMBERS Actel 955 East Arques Avenue Sunnyvale, CA 94086 (408) 739-1010 CrRCLE 311 ON FREE INFORMATION CARD AD*Vance Magnetics 625 Monroe Street Rochester, IN 46975 (219) 223-3158 CIRCLE 312 ON FREE INFORMATION CARO American Colloid Co 1500 West Shore Drive Arlington Heights, IL 60004 (708) 392-4600 CIRCLE 313 ON FREE INFORMATION CARP Amuneal 4737 Darrah Street Philadelphia, PA 19124 (215) 535-3000 CIRCLE 314 ON FflEE INfOHMATION CAflD Aremco PO Box 429 Ossining, NY 10562 (914) 762-0685 CIRCLE 315 ON FREE INFORMATION CARD Fair-Rite POBoxJ Wallkill, NY 12589 (914) 895-2055 CIRCLE 316 ON FREE INFORMATION CARO FerriShield 350 Rflh Avenue, Ste 7505 New York. NY 10118 (212) 268-4020 CIRCLE 317 ON FREE INFORMATION CARD Ferroxcube 2001 West Blue Heron Blvd Riviera Beach, PL 33404 (407) 681-3200 CIRCLE 318 ON FREE INFORMATION CARD Steve Hansen 35 Windsor Drive Amherst. NH 03031 (603) 429-0948 CIRCLE 319 ON FREE INFORMATION CARD Intermark One Pen Plaza, Ste 4526 New York. NY 10119 (212) 629-3620 CIRCLE 320 ON FREE INFORMATION CARO Jones & Sartlett 20 Park Plaza Boston, MA 02116 (617) 482-3900 CiRCLE aai ON free information card Magnetic Shield Corp 740 North Thomas Drive Bensenvilie, IL 60106 (708) 766*7800 CIRCLE 322 ON FREE INFORMATION CARD Management Roundtable 1050 Commonweallh Ave, Ste 301 Boston, MA 02215 (800) 338-2223 CIRCLE 323 ON FREE INFORMATION CARD Mini-Circuits PO Box 350166 Brooklyn. NY 11235 (718) 934-4500 CIRCLE 334 ON FREE INFORMATION CARD Murata-Erie 2200 Lake Park Drive Smyrna, GA 30080 (404) 436-1300 CIRCLE 32S ON FREE INFORMATION CARD Siemens 2191 Laurel wood Road Santa Clara, CA 95054 (408) 980^4500 CIRCLE 326 ON FREE INFORMATION CARD Synergetics Box 009- RE Thatcher, AZ 85552 (602) 428-4073 CIRCLE 327 ON FREE INFORMATION CARD Tesia Society/HE Enterprises PO Box 5636 Security, CO 80931 (719) 475-0918 CIRCLE 32B ON FREE INFORMATION CARO tn' to 70 Interlaced scan is used by NTSC to minimize flicker But interfaced scan is totally unsuitable for data dis* plays, especially small text! The rea- son is that interlace works only if successive lines are more or less the same. This is clearly not the case between dot lines of finer text. Thus, most computer screens demand a noninterlaced display where each field is complete and identical. Most computer monitors also will use a 59,94' or a 60-hert2 vertical scan rate. Less than that and you* II end up with too much flicker If you try to lengthen the phosphor per- sistence you may end up with "com- ets" for traveling balls. The horizontal scan rate is decided by how many horizontal lines you are using per field. As you increase the number of lines in a display the hori- zontal scan rate goes up. Scan rates from 22 to 45 kilohertz are typical With some exotic displays going much higher Now for the kicker: Most monitors will work only over a VERY limited range of horizontal scan frequencies! Unless you go to some ^ery fancy multi-sync techniques. WIDTH ADJUST ^ DEFUECTION MOBRONTAL OUTPUT SMtTCH Hi DAUFER FIG. 4— MULTI-SYNCING MONITORS change their sweep values to try and match an input horizontal scanning rate. But once selected, ihey still operate only over a very limited frequency range. Flyback deflection Why can't someone just build a monitor that accepts an uitra-wide range of horizontal scan frequencies and be done with it? The answer to that has much to do with both energy conservation and the way things ha^e been done rn the past. A set of coils known as a deflection yoke normally goes on the neck of the display tube. These are plain old coils that will move your electron beam to whefBver you want it to go. Normally, the horizontal yoke is where ail the action is* since it does things several hundred times faster than the vertical one. Since several kifowatts or more of deflection power are in^^lved in the horizontal deflection of a larger color display* sneaky tricks will have to be played to reuse and recycle all of the energy involved. These sneaky tricks go by the name of recurrent flyback deflection, and are shown to you in Rg.3 The basic rule of any inductor is that... e-LAt/Al Let s rearrange things a tad... Ai/At = e/L Now Ai is the change in curmnl and At is the change in time, so Ai/At will be a linear curwnt ramp whose rate of change should equal your supply voftage divided by the inductance of your horizontal yoke. Say that the switch in Fig. 3 is now open and has been that way for a long time. There is no current in the yoke, and no deflection. The spot will still be in the middle of the line. Now, close the switch, but just for around one-half of the Irve scan time. What happens? We now apply a positive voltage to an inductor and start building a linear current ramp. That current ramp in the deflection yoke creates one linearly increasing magnetic field, and the spot moves to the right. When you get to the right side of the screen, you'll have bunches of energy stored in the hori- zontal yoke s magnetic field. What are you going to do with it? If you just bum it up as heat, you'll end up with bad reliability and high power consumption. Besides needing far tougher electronics. Instead, let s work smarter instead of harder Open your switch. Your equivalent circuit now consists of a yoke coil in series with the flyback capacitor A standard and high-Q series-resonant circuit. But one that started out with zero volts on your capacitor and a strong current thn^ugh the coil. At this time, all of the energy is in the coil and none is in the capacitor. Let the circuit resonate for a while, exactly like any other series-resonant circuit. In one quarter of a cycle, the capacitor will be charged up to a large positive voltage, often in the 80C>-1200 volt range. At the peak, the current will be zero, and the indue- tor will be "empty" and field- free. You have now transfermd all of the magnetic energy that was in the yoke into electncaf energy stored in the flyback capacitor! And done so with very little loss. Let the circuit continue to reso- nate. The current will reverse in direc- tion, and energy will start transferring back into the inductor Note that the current is now going in the opposite direction. Let the circuit resonance continue ilUE ®- ®- ©- VEflT SYNC (u)^ QTOIJNO 0 -0 -Q GR£EJ( -Q GttEN GROW -@ H«l SttiC -(Jo) HS/WC -@ VERT SYNC WVKC GBOUM) HC (7) Mac ^ — . VGA De^S rmt (V) NC MC Qs) VGA RG. 5— THE MACINTOSH LC definitely can NOT be used with a NTSC monitor But this simple cahfe and jumpenng lets yau yse it with most VGA color monitors. Tbe configuration jumper from pin 7 to pin 10 selects VGA scan rates and standards. until the capacitor gets to zero volts. You will now have placed all of the onginal magnetic energy right back into the deflection yoke, with one very important difference; Since the current is going in the opposite direc- tion, you^iB now at the maximum left spot position, compared to the max- imum right that you were half a reso- nance cycle ago. And. again, you have done this with very little loss. This pnxess ts known as a flyback. and the retrace interval is called the flyback time. The beam is turned off during the flyback time so the retrace is invisible. Let the circuit resonance try and continue. The flyback capacitor will try and go negative but. at that time, a damper diode wilt turn itself on. Your circuit now consists once again of a coil connected between a positive voltage and ground. It will once again start generating a positive current ramp Only this time, it starts fre>m a negative initial current. Thus, your sweep starts linearly moving from the left to the center As you move on towards the center of your scan line, the yoke energy gets sent back into the positive supply. When you get to the center of the screen, you once again close your switch to repeat everything for the next cycle. The damper diode shuts down just as soon as you cross cen- LEARIV VtR CLEANING/MAINTENANCE/REPAIR EARN UP TO S1000 A WEEK, WORKING PART TIME FROM YOUR OWN HOME! Be an FCC LICENSED ELECTRONIC TECHNICIAN! THE MONEY MAKING OPPORTUNmr OFTHE1350"S IF you able lo wofli with comman sm^ll hand tQQ&, and are familiar wit!) bisc dectrixiscs^ Id ust M^tltnutet mitleibJUiMt DC tUtxSstsmcsX . . . iFyou possios ii^fage mectaniod Mty. and VCRonvMtlQpradioeMllevii. , mefi«cczii teadi VWVDt ma i n l enan ec and repaii* FACT ; u p ro 90% of ALL VCfl maHunctiOfis are uc to ^impre MECmNfCAL or ELECTRO-MECHAMICAL breakdowns' FACT: over 77 rniElion VCRs rn use today nabonwide! AvefaQf* VCR ne^S service or repair every 12 to t8 montbsi Wcia s 400 PAGE TRAIKING MANUAL (over 500 phO' tos and illustrations^ and AWAI^D ^WINNING VIDEO TBAIKIHG T^^PE reveals the SECRETS Ql VCR rrtaime- nance and repair— "feal world" inlormalion IM is NOT itvniliiblc cEsewherel Also includes aM the ir>lD you'iJ need r&Qarding BUSINESS-SIDE al funmng a successlu! service op- craliOii" IHFORWATIOH CALLTOa^FHQ I a(IO-&37^tSS9 Or Mtite itr. Vie^D PubtiCiiions inc 53?9 hyarmn ktt Los Angefe?. CA 9QO?9 Dm -^■^ L^Srn a.t home in ipar^Xln^ ' I > n 1°^^ eipengnce needed! No cosUy schooE, No comntutrnf^ to class. The Original Home-Study course prepares you fm the "FCC Commercial Radio- telephone License." This vmluahle license is your professional ticket" to thousands of exciting jobs in Communications, Radio- TV» Microwave; Maritime Radar. Anoiucs and morc.di'eii start your own business! You don't need a college degree to qualify, but you do need an FCC Licence. No Need to Oult Your Job or Go To School This proven course is cosy, fast and low CQSlf GUARANTEED PASS-You get your FCC License or monej' refunded. Send for FREE facts now. MAIL COUPON TODAY! ^ commariD VroduYtIoHs" " FCC LtCEtlSE TH AIMING, Dt?pL 90 P.O. Box 2B24. S3r> FrBnclsco. CA 94126 Please rush FREE details immedlaielyl CIT¥ S 1 Q. 9 m o 8 71 CIRCLE ia7 ON FREE INFORMATION CARD ter screen. Automatically. Once again: Close your switch to move from center to right. Transfer the coil energy to a flyback capacitor Resonate half a cycle and transfer the Flyback capacitor energy back to the coil inverting its sign and putting you far left. Turn on the damping diode to move from left to center. And repeat the process once each scan line. Several details I've omitted: That f^back pulse also gets sensed and routed to a current step-up trans- former called a flyback transformer The flyback transformer steals a minor part of the energy and uses il to create the high voltage DC supply that is needed by the display tube- Other windings can be used for blanking, horizontal phase com- parison, and boosted supply voltages elsewhere in the TV or monitor. And games have to be played to keep any uncenter DC bias out of the horizon- tal yoke. But regardless of these de- tails, the basic concept of recycling your deflection energy remains. This very elegant, highly tested, and ultra conservative flyback scheme inherently works best only at one horizontal scan frequency. And that is why you can*t normally get a monitor that can accept any old hori- zontal rate. Yes, there are multi-sync monitors. These usually work by measuring the intended input scan frequency and then switching in one or more flyback capacitors and adjusting the supply voltage accordingly, Figune 4 shows one multisync scheme. Once switch- ed, a multisync monitor is a narrow- band system just like any other flyback-driven circuit. VGA for the Mac LC The Macintosh LC computer was designed for use with the Mac color monitors to the Mac color standards. Since these can be expensrve, lots of hackers are often on the lookout for lower-cost substitutes. But note that you definitely can not use an NTSC color monitor because of the higher scan rales on the LC. And also do note that you should never buy a substitute monitor with- out making certain it works and is good enoi'ch for your uses. Happily, there is a hidden "secret" provision on the Mac LC that lets you change your LC output so it is VGA- compatible. Quality VGA monitors are often available much cheaper in far wider selections than are "reai^* Mac monitors. The secret jumper that changes the LC scan rates for VGA com- patibility is shown in Fig. 5, GPS Nav resources From time to time v/e've looked at the Navicube concept right here in Hardware Hacker. The Navicube is a magic $5 cube 3 inches on a side which always knows where it is and which way it is pointing. Several re- cent developments that should ulti- mately make the Navicube possible inctude low-cost accelerometers, ad- vances in fiber-optic gyros, and the ongoing GPS navigation system. GPS is short for Global Positioning Satellites, a military navigation sys- tem that has recently seen several dramatic improvements in price, re- liability, and availability. Tve tried to gather together some GPS info for you as this month s resource sidebar The system consists of a flock of roving satellites, any five or six of which should be overhead at any given time. The satellites broadcast a series of low microwave-frequency radio signals. By intercepting and comparing the signals from several overhead satellites, you can extract your current absolute position and do so to around a fifty- foot accuracy. Your speed, acceleration, and current time can also be determined to sur- prisingly high accuracies. Within two inches per second even. And by shifting to a differential scheme from any one known and fixed point, you can improve your ac- curacy to a fraction of an inch. Amazingly, the antennas needed are no big deal. They can easily fit inside a small shoebox. Unlike video satellites, the GPS antennas need a wide beam width, a narrow- frequency bandwidth, plus a pseudorandom modulation which works acceptably well with lower signal-to-noise ratios. The antennas do require line-of-sight operation, so they have to be used outdoors, on a rooftop, or on the top of a vehicle or boat. Since the reception electronics are incredibly complex, it is unlikely that you would want to try and build up your own GPS receivers by using dis- crete components. Thankfully, sophisticated chip sets are now becoming readily available from Rockv^etl, Magellan, and others. Their initial pricing is in the $500 range. But it is reasonable to expect Japanese GPS chips within a year or two for under S35. So now is the time to start on your GPS hacks. The leading trade journal in the field is called, of all things. CPS World. It is free to qualified subscnbers. An inter- esting hacker newsletter that deals with navigation and communications of interest to cavers is Frank Reid s great Speleonics. Some other GPS info appears from time to time in NASA Tech Briefs. Several other sources of GPS gear include Asbtech, Bancomm, Texas Instru- ments, and Trimble Navigation. Trim* ble has a nice GPS intro book available- It's called GPS— A guide to the next utility. New tech lit From Act&i a new databook on Field Programmahle Gate Arrays. And fn^m Mini-Circuits a new RF/tF Signal f^cessing Guide on higher frequency mixers, splitters, ampli- fiers, trBnsformers, and such. Their broadband amplifiers cost around a dollar or so each. A free update on our Santa Claus machine technology is now titled an Insiders Guide to Rapid Prototyping, and is available from Management Roundtable. These folks also put on annual conferences. A new quarterly hacker newsletter on lower-cost vacuum projects and techniques is now available through Steve Hansen. It's called The Sell Jan Free samples of Liquisorb. a low- cost comstarch coltodial absorbent, are available from American Colloid Company. Since these sample pack- ets dramatically swell up in the pres- ence of liquid water, one obvious use is as a low-cost flood alarm. And thnDugh Aremco. a Materials Catalog MJ2 that includes a wide va- riety of high-temperature ceramic matenals. Including machinable and pourable versions. For the fundamentals of digital inte- grated circuits, be sure to check out my classic CMOS Cookbook and TTL Cookbook. You can also reach me via CEnte PSFTT C800) 638-9636, where you'll find lots of resource stuff not available elsewhere. R-E AUDIO UPDATE Reader questions: Real and imagined, serious and silly LARRY KLEIN After several decades of an- swering readers' hi-fi ques- tions for various electronics and audio publications, one can get a little nostalgic. \ look back with fondness to the days when I had all the answers — or at least thought I did — and was pleased to provide them to curious readers. Today I cer- tainly don't have all the answers, and occasionally 1 don't even understand the questions. In any case, herewith is a selection of updated Q's and As that* if not my greatest hits, at least reflect some of the interesting con* cerns of the audio public in the last decade. Subliminal Satanism / keep hearing that some heavy- metal rock bands put subliminal Sa- tanic messages on their albums. The messages are supposedly in the form of yvords recorded in reverse at the ends of certain cuts. What effect do these messages have on listeners? L.a Everetts, NC Mostly It causes them to write silly questions to magazine columnists. The term "subliminar" is usually ap- plied to stimuli that are outside the range of conscious perception but are nevertheless said to reach the brain and affect thinking. The pur- ported danger in such a technique is that the messages bypass conscious evaluation and cause their hearers Cor viewers) to uncritically buy products, vote for certain candidates-., or wor- ship Satan. Since there appears to be no legitimate research indicating any effect at all from subliminal motiva- tional messages, good or bad. 1 wouldn't worry about it... unless, of course, you experience sudden inex- plicable urges to buy large quantities of toothpaste, to vote for Jesse Helms, orjoin your local coven after a long evening of heavy-metal head banging. My comments also apply to "sub- liminal" self-help tapes. A recent study by the National Academy of Sciences concluded that such tapes "have no proven value." That seems logical, considering that any mes- sages recorded below the threshold of hearing would necessarily be bur- ied in normal tape noise. Record and tape wear / hope you can settle a bet for me. I maintain that, unlike LP records, cas- sBttes don t wear out. My friend in- sists that they both wear with use. And what s the situation with CD lon- gevity? I've tead some troubling re- ports lately JS. Evanston, IL They both wear but the effects are different for tapes and discs. When vinyl discs begin to wear noise and distortion are added to the signal. Worn tapes, on the other hand, tend to suffer signal losses. There are mo- mentary "dropouts" that reflect damage to the tape's oxide coating caused by friction against the player's heads, capstan, and guides. There may also be a partial erasure of the high frequencies brought about by an accumulation of residual magnetism in those same metal parts. Periodic cleaning and demagnetizing of the player help minimize the damage. Over time, there may be a marked increase in cassette wow and flutter Assuming that the player is okay and that the tape or the cassette shell mechanism has not been damaged through overheating on a cars dashboard, the fault is probably caused by an overly tight winding in- Side the cassette. The tape pack can be restOfBd to its normal looseness by repeatedly, but gently slapping the cassette face down against a semi- hard surface such as a magazine or book. Squeal can sometimes be helped by a very small amount of sil- icone lubricant applied in the areas where the tape hubs meet the shell, but most of the lime it reflects a prob- lem (sometimes brought about by aging) in the composition of the tape coating. Recently questions have been raised about CD longevity, with claims that CDs suffer from 'laser rot" over time. The reasons given for the self-destructive tendencies of CD's have been varied, but the claim is that todays CD's have, at best a very limited life span. I think that such predictions should be taken with a sack of salt, consider- ing their original sources are the same "underground" audio publica- tions that disparaged CD's from the outset. I spoke to a gentleman in charge of preservation research at the Library of Congress, and he says he knows of no evidence that supports the viev/ that normal, property manufactured CDs will spontaneously "fail" over time. All of which is not to say that some CD's haven't had playback problems because of mishandling or manufacturing defects, Undriven drivers JherE 's a hi-ff dealer in my area who features what he calls '^Single Speak- er Demonstrations. "He claims thattt was discovered in England that the presence of other non- playing speak- er systems in a listening room can affect the sound produced by the playing speakers. Does the removal of non-playing speakers really help a listener evaluate different systems more accurately? dS. Los Angeles, CA I don't think so, particularly since it would certainly prevent a fest A/B comparison between systems. It s probable that there is a slight mea- | surable acoustic effect in a show- ^ room produced by stacks of ^ unconnected speaker systems. The- pS oretlcally. acoustiC*suspension m speakers would function as g-- Hefmholtz absorbers at the frequen- m cy of their system resonances, and S vented systems would do the same | at their port resonances. In either S case, the suck-outs would occur in the same low-frequency areas where 73 most standing-w^/e problems occur and conceivably might moderate the effects. But given the very large CIO— 20 dB) bass- response irreg- ularities found in most rooms — in- cluding deater demo rooms — it seems unlikely that even the most golden of ears coutd isolate a positive or negative effect produced by the presence of a dozen or so undriven speaker systems. Incidentally. I understand that some lunatic fringe audrophiles even advocate removing telephones, clocks, and watches from listening rooms in the belief that they some- how resonate destructively with the music. As with so many other super- stitious beliefs, this one also has in it a small — very small — grain of truth. If you were to feed an audio os- cillator through your system and sweep it slowly at high volume from, say. 40 to 200 Hz, you would find that small and large objects in the room vibrate slightly at their specific reso- nant frequencies. But with music there is usually not enough sustained acoustic energy at any one frequency to produce audible resonances. How- ever, it is not a good idea to place small art objects on top of your speakers as there might be enough coupled vibration to cause them to dance sympathetically lo whatever tune is playing. Sotiic shatter I'm curious about the otd Merrtamx wine glass shattering commerciafs. Exactly what technology was in- vol\^d? Was ft anything like Caruso s vocal trick? MH Mendenhall, MS Like ail good wine glasses, the goblets used in the commercial were both rigid and relatively fragile. To cali- brate the goblets, each was placed directly in front of a loudspeaker driv- en by an audio oscillator The os- cillator was swept slowly through the range of approximately 700 to 850 Hz, which covered the resonant fre- quencies of the glasses used by Memorex. During the frequency sweep a finger resting lightly on the rim of the goblet could easily detect the increase in vibration at the goblet s specific resonant frequency. That was marked on the crystal goblet for futurB reference. At glass -breaking time, a tape re* cording (on a Memorex cassette) was made of the celebrity singer pro* ducing a sustained note at the pre- viously determined critical frequency. When the cassette tape was played back very loudly through a speaker, the wine glass — which had an ap- proximately 140-dB sound field im- pinging on it^ — would react by flexing itself to pieces. Given the above, it should be clear that shattering a glass by an un- amplified voice is no easy trick. Not only does the singer have to produce an enormous sound pressure level but also the frequency has to be with- in a hertz or so of the wine glasss specific — and unknown — resona nt frequency. Perhaps in Caruso s day voices were stronger and crystal more fragile. R-E uo-t it-oHitf tLitt. rjutnincpAU. n IIJJI rust* ^.■Tt^iMmMitt" 14 trTu V ^ a *>C i «-»^ t • |i li It n It f imn/31 i^-'t it'CDOlITT ILTB. tJUlNlllQiUtCp Wl 11739 r One tree can make J,000,000 matches. f \ One match can burn ivOOOjOOO trees- DRAWING BOARD More on automotive voltage regulators. ROBERT GR055BLATT Once again I have to apologize to everyone out there who's waiting for us to get back to the design of a digital scope. We won*t be doing that until next time because I need this space to finish going through our discussion of gen- erators, alternators, voltage reg- ulators, and all the rest of the stuff you meet when you take a trip to the always amazing world of charging systems. As I mentioned last time. I was amazed by the amount of interest in this and. as a certified member in good standing of the old car and bike freak club (with a particular emphasis on British stuff), my duty is clear. We've already gone through the basics of the charging system and seen that iheie are really only two ways an alternator can be wired into a bike or car One side of the fieid wind- ing Is tied to either the hot side of the battery (a pulled-up field), or to ground Ca grounded field). Most Brit- ish cars and bikes use a pul!ed-up field and you'll find a lot of American cars using a grounded field. I said this last time but it's really important so let nne repeat it. Before you can build your own voltage regulator, you HAVE to know how your alternator ts wired. Using the wrong regulator will de- stroy the regulator and probably trash the alternator as well. The easiest way to tell what sys- tem is used in your car or bike is to use a multimeter With the ignition tumed on, but the engine not running, measure the voltage from the hot side of the battery to the terminal marked "F" on your existing regulator. If you get a reading between 12 and 13 volts (the battery voltage), your car is using a pulled-up field. If you get a zero, or near-zeno read- ing, you re probably looking at a grounded field. You can make sure by reading the voltage from the reg- ulators "F" terminal to ground. You should see the 12- to 13-volt battery voltage there. If you don't see the battery voltage anywhere you either have a bad connection oryou*re mea- suring from the wrong terminals. Check the multimeter leads and. if that doesn't cure the problem, get out a flashlight and trace the wires. You absolutely have to know what youVe dealing with before you add a voltage regulator! Anyone who finds that they have a pulled-up field can slop reading right now and skip ahead a bit because the regulator we designed last month is exactly the one needed. If you*ve got a grounded- field alternator, there s still some wor1< to do. The regulator we designed has to be modified be^ fore you can use it. The easiest way to see the changes is to compare the original pulled-up field circuit (fast month's Fig. 3) to the modified design for a grounded-field regulator shown in Fig, 1. One of the first things you should notice is that R7 and R8 are now in parallel. Electrically there's no real reason for having those two re- sistors in parallel The only reason I left them both there is to help make the similarity between the two cir- cuits more evident- You can leave them wined in parallel or simply do the arithmetic necessary to come up with an equivalent single-resistor rep(ace- ment. The major change to the circuit is that the alternator field connection is now made off the emitter of 03 rather than the collector. All the changes in the circuit are aimed at varying the voltage at Q3^s emitter The DaHington pair made from 02 and 03 is still controlled by the voltage at the collector of 01 in exactly the same way as it is for the pulled-up field regulator. The positive feedback (supplied by C3 and R8) that speeds up the switching of the circuit from fully on to fully off now comes from Q3's emitter rather than its collector. The reasons for the changes in the circuit are all based around the idea of being able to vary the output voltage. Since, in the case of a grounded field, the given is that one side of the field is tied to ground, the job of the regulator is to increase the output voltage at the "F" terminal when the control voltage at the base of 01 falls below the point set by RiO. The LED has been moved so it will monitor the field voltage and Dl has been moved so it can soak up any back-voltage gener- ated when the alternator field collaps- es. You'll also see that the value of R7 © © iok, — cf^ ^PEJt TO >e7 0 C3 g© / © % c 9- 9 m o RG. 1— COMPARE THE ORIGINAL pulled-up field circuit (last month's Rg. 3) to the modified design for a groundod-fleld regulator shown here. 75 R-E Engineering Admart FCC LICENSE PREPARATION The FCC has revised and updated the commercial license exam. The NEW EXAM covers updated marine and aviation f ules and regulations, transistor and digital circuitry. THE GENERAL RADIOTELEPHONE OPERATOR UCENSE - STUDY GUIDE contains vital information. VIDEO SEMINAR KITS ARE NOW AVAII_ABLE. WPT PUBLICATIONS 979 Young Street, Suite E Woodburn, Oregon 97071 Phone (503) 981-5159 Dept. 50 CIRCl-E 1S1 on FREE INFORMATtOH CAf^D Rates: Ads are 2y4"x2Vi\ One insertion $995 eacli. Sh insertions S950 each. Twelw insertions S925 eacfi. Closing date same as fegular rate card. Send order with remittance i Engineering Admart, Radio-Eiectromcs Magazine, 500-BBi-County8lvd.. Farmlngdale, N' 11735. Direct te[eplione inquiries to Arline Fishman, area code-1-516-293-3000* FAi 1-516-Z93-3TI5, Only iQO% Engineering ads are accepted for this Admart. HlghPow«r Audio Amplifier CofiBtmctlon HIGH POWER AUDIO AMPURER CONSTRUCTION BP27 7— Here's background and practical de- sign information on tiigti power audio ampli- fiers capable of 300-400 watts r.m,s. You1l find MOSFET and bipolar output transistors in inverting and non inverting circuits. To order your copy send $6.25 plus S2.50 for shipping in the U.S. to Electronic Technology Today inc., P.O. BoK 240, Massapequa Park, NY 1176MZ40, MIDI PROJECTS ^, ProJ«6t» ' i BP1fl2— MIDI interfacing enables any so equipped instruments, regardless of the man- utacturer to be easily connected together and used as a system with easy computer control of tfiese music systems. Combine a computer and some MIDI instruments and you can have what is virtually a prog rammable orchestra . To order your copy send S6.95 plus $2.50 for shipping in the U.S. to Electronic TechnQlogy Today Inc., P.O. Box 240, Massapequa Park, NY 11762-0240. P5 TO j4LT^M/VATOR, FIG. 3— PARTS-PLACEMENT/wmiNG DIAGRAM. Use at least t4-gauge wire for the three connections to the vehicle's electrical system. has been dropped to 100 ohms but. as 1 said earlier, you can replace it and R8 with a single resistor Before we take this any further, a word or two has to be said about C3. When the voltage on the output side of the regulator changes, some volt- age is bled off through C3 and used to help speed up the action of the regulator That is true both when the regulator is supplying current to the alternator field and when its shutting the field current down as well. So, when the regulator is working, cur- rent will flow back and forth through C3. Whenever you have that situation with an electrolytic, the right compo- nent to use is a non-polarized capaci- FIG. 2— FOIL PATTERN for the grounded- 76 field regulator. tor Telephone circuits use them ail the time, tf you can't find a non-polar- ized electrolytic of the proper value, a standard substitute is to use a pair of polarized capacitors wired front-to- back in parallel When J was building the circuit. I drdn*t have a non-polar- ized 22 fJiF capacitor around so, since I was tn a hurry to get the circuit in my car, I just used a regular polarized capacitor instead. Once the car was back on the road, I figured I'd be able to drive to the parts supplier, get the right component, and make the cor- rect substitution. That was several years ago and. even though I've made many trips to Capacitors R-Us since then, I've nev- er replaced the original polarized ca- pacitor. I know it s the right thing to do but I ve never gotten around to it. The choice is yours. The foil pattern for the grounded- field regiifator is in Fig. 2. and the partS'placement/wiring diagram is shown m Fig. 3. If you have last month's column around, you'll see that the new pattern is not very dif- ferent from the pattern for the pre- vious regulator Once you have the regulator ready to install in your car, use at least 14- gauge wire for ihe three connections to the vehicle s electrical system. Re- member that the field windings in the alternator have an jmpedance of only about four ohms so. with a minimum of twelve volts from the battery, the wire has to carry at least four amps. If you have any doubts about the gauge of the wire, use the same stuff that was there originally. The only other precaution to take when you're using either one of the two regulators is to realize that, since they're designed to be adjustable, they're capable of making the alter- nator pul out a lot of power While that isn't so bad for short periods of time, having the electrical system run at a constant level of sixteen or seven- teen volts is a good w^ to blow stuff up. As soon as you have the circuit connected and you're sure that the whole charging system is working, spend a little bit of time with your multimeter to calibrate the potenti- ometer 7294^10 i/H ELECTRQf^iiCS BqQK JB XiV Blue Ridgo Summit, PA 17294-0810 Z Y£Sf P^ea&d Accepx my membership in tOo Beet tonics Bock Club and send lbs 5 volume^ u&lwl belcWn billing me S4.9S. 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A won- derful book for the expen- frien!cf 1 i BF3gS— INTEflNA- ^ TIOMAL RADIO STA- TIONS GUIDE $7.93. Provides the casual ils- lened, amateur rcidio DXor and tho profcEsional radio monitor wHK an ossonttal roloronc^f work designed lo guido him or h&r around ihan e\/Gr moro comptox ra- dio bands, MAIL 10 Electronic Technology Taday. Inc. PO Box 240 Ma^sapequa Park. NV 11762-02^0 SHIPPING CHARGES IN USA AND CANADA S0.01 1OS5.00 . S5.01 to S10 00 S10.01 ro EO.OO S20.0I IQ 30 00 . SI .50 $30.01 to 40.00 . . S5.50 $2 50 S^O.01 to 50.00 .S6.50 .53.50 S50.01 and above . Sfi OO .S4.50 SORflY, Nd orders accepted oulside ol USA aria Canada Tata I p nce ot merct^andi^e ShippirfQ (see cfiart) Subtotal Sales rax(NYS only) MM Eficiosed ... . Name Address ^ City -Slate . COMPUTER CONNECTIONS JEFF HOLTZMAN Multimedia mayhem MULTIMEDtA APPLICATIONS GRAPHICAL ENVIRONMENT WITH MULTIMEDFA EXTENSIONS CPU MEMORY DISK VIDEO Multimedia. It may be the first overhyped buzzword of the 90 Or it may be the begin- ning of Gutenberg IL Gutenberg I oc- curred around the year 1440, when Johannes Gutenberg invented mova- ble type, thus clearing the way for high-volume printing. Hfgh-volume printing did two things: it vastly in- creased the variety of literature avail- able, and it vastly increased the audience For that literature. Sixty years later, millions of books had been printed, and Europe was home to thousands of what we today might call "QwikPrint" shops. Five hundred and fifty one years later, we're on the threshold of another revolution in publication technology Gutenberg I brought to the masses media for the efficient transmission of language: Gutenberg II will bring to the masses media for the efficient transmission of all aural and visual information. That's a grandiose claim. Howeven the confluence of several social and technological factors makes it a likely one. Socially traditional forms are los- ing out to other media. Literacy is dropping; mixed-media forms of edu- cation and entertainment are becom- ing increasingly popular. People depend more on CNN than the New York Times to keep abreast of current events. Computer-generated graph- ics receive frequent showings in ma- jor art centers. Electronic music has received the attention of serious t\j composers. Live drama is now min- uscufe compared to film. Traditional b print publishers are dabbling in new g forms — books on tape, encyclope- ^ dias on CD-ROM. And video games g are preparing an entire generation for "I a lifetime of interaction with eiec- o tronic media. High schools are gradu- iD ating illiterate, innumerate people; to ■g compensate, corporations are spending billions educating, re- educating, and pneeducating this in- S4 creasingly unqualified work force. FIG. 1— MULTIMEDIA ARCHITECTURE provides a standard interface for multi^ media applications to build on. You may bemoan the loss of tradi- tional modes of communication — and I would join you. Nonetheless, its happening. So you can either throw up your hands or find a way of pre- serving the old while embracing the new. And that's where multimedia fits in, Gutenberg II In addition to those social factors, there's a whole lot of technology coming together to set the stage for Gutenberg II. The basic architecture is shown in Fig. 1. Multimedia demands computing power including a fast CPU, lots of memory CRAM) and permanent stor- age (disk), and high resolution video. Now this base technology level is here, at affordable prices. On top of the base technology layer is a user-friendly graphical en- vironment, with special extensions to VENDOR INFORMATION SideBar ($99.99), Paper Software. RO. Box 667, New Paltz, NY 12581. (800) 551-5187, (914) 255-0056. CIRCLE 41 ON FREE JNFORMATtON CARD High-Tech Ventur^Sf The Guide for Enlre- preneunai Success, (S29,25) C, Gordon Bell and John E. McNamara^ by Addison- Wesley, Aprit 1991. CIRCLE 42 ON FREE INFORMATION CARD handle new media (sound cards, CD- ROM drives, MIDI interfaces, laser- disc and Other motion video sources, etc.). The graphical environment is a highly contentious area right now, but recent events lead me to the con- clusion that when all the smoke clears, there's going to be much less different among the competing sys- tems than there is in common. Win- dows, OS/2, and the Mac environ- ment are all headed toward stan- dards. Architectural layering will hide underlying technologies, so it won't matter whether you're running the Mac Finden Windows' Program Man- ager, or the OS/2 Desktop. It'll mat- ter even [ess whether its an Intef or Motorola CPU under the hood. When you plug in the latest multimedia ex- travaganza, it 11 just run. At the highest level are the applica- tions. There are some 2500 CD- ROM titles in ^^print"' right now. Few of these are multimedia based; the vast majority consist of pretty boring text/numeric databases. However several dozen full multimedia titles will be released between the time this is written and the time you read it; 1992 promises the release of hun- dreds of new titles. Such as? How about: Comptons Multimedia Ency* clopedia, the Guinness Multimedia Disk of Records, Just Grandma and Me: A Broderbund Living Book, Countries of the WoHd, Composer Quest, The Electronic Library of Art, Beriitz language lessons (Spanish. French, German. Italian). Great Cities of the World, Battle Chess. SimCity, The Macmillan Dictionary for Chil- dren. Multimedia Beethoven. Intro- ductory Games in French and Spanish, Worid Atlas, Desert Storm. There are other factors contribut- ing to this revolution in publishing. Hypertext research initiated by Ted Nelson in the early 60's plays a promi- nent role. Advances in cognitive and mstructional psychology also contrib- ute significantly TAeie 1— MULTIMEDIA HARDWARE LEVELS Component Bas^ Lfivfil Power User Devefoper CPU 80286/10 MHz 80386/25 MHz 80486/33 MHz RAM 2 MB 4 MB 16 MB Hard disk 30 MB 80 MB 0.5-1.0 GB Video VGA (16 color) VGA (256 color) 1024x768x256 color, non-interlaced, video overlay upiiCai siorage CD-ROM wilh audio output Audio* 8-bit DAG, 8-bit ADC, 1 1 and 22 kHz sampling rates. 16-bil DAG and ADC preferred. Multi-voice synthesizer. MIDI *Nole: Required for upgrade kit ' Getting in step Cliances are you don't own a multi- media-compatible PC right now. But as those titles are reieased, you're going to start thinking stnangly about buying one, or about buying an up- grade kit for your existing PC Cor buy- ing separate components for an upgrade.) Microsoft has defined a basic mul- timedia PC as shov^n in Column 2 of Table 1; performance-conscious users wtll want a system like that in Column 3; developers will opt for something like Column 4. An up- grade kit consists of a CD-ROM drive, along with an audio board that provides ADC, DAC. and MIDI sup- port. NCR. CompuAdd, Tandy. NEC. Olivetti. Zenith, Fujitsu, and Philips have all announced or begun shipping multimedia PCs; prices start around $2500. Upgrade kits starting around $700 are available from CompuAdd, Creative Labs, Headland, Media Vi- sion, and Tandy It s only a matter of time before all major hardware vendors provide sim- ilar offerings- Standards and competition Microsoft initiated formation of a trade group, the Multimedia PC Mar- keting Council CMPMC), Since its for- mation, however, the MPMC has attached itself to the Software Pub- lishers AssQCiatton, thereby guaran- teeing that no one vendor's interests will be served at the expense of olhers^ — or the consumer's. Nonetheless, there is IBM. which has been strangely silent about the MPMC. The IBM/Microsoft battle is one thing, but bear in mind that IBM is heavily involved in multimedia tech- nologies. A few years ago Big Blue introduced a touch-screen system that is widely used in training applica- tions. The company has an entire divi- sion dedicated to educational sys- tems; it has funded or sponsored projects that we'll soon be hearing lots about, including one on the voy- age of Columbus, Other IBM titles include Ulysses, the Declaration of Independence, and Hamlet. Expect a strong showing — when IBM is ready There are some other technologies that have been hanging around for years, waiting to become economical and adopted by large numbers of users. DVI (Digital Video Interactive) is one; CD-I (Compact Disc Interac- tive) is another It s too soon to tell whether the Microsoft/MPMC stan- dards will really take hold. Its likely that they will, however These stan- dards are comprehensive, are built on general-purpose computing plat- forms, and are supported by a fairly broad spectrum of vendors. Why would the average consumer buy a CD-I player when he or she can get the same effect on a PC that also allows word processing, checkbook balancing, etc? DVI. CDL and similar technologies will either become com- pliant with emerging standards, re- main as they are and carve out niche markets, or simply die. Conclusions Above I said that Gutenberg II would support all sound and visual information. Want to guess what O dird d.r.- — I' Oh':-: [books] fpcindex] [sic] [-1 image. b&k irr'iage.dat junk ireeinfo.ncd FIG. 2— SIDEBAR Is the most elegant Win- dows shell on the market. It won't over- load you with features; rather it adheres to a small-is-beautifyl philosophy. Nice work. Gutenberg 111 will support? Even bet- ter, when it'll happen? News bits Intel's microprocessor line is com- ing under increasing pressure. Chips El Technologies^ which has suffered financial hardships in re- cent years, has bet the farm on two new chip fines that the company hopes will restore it to the glory of former days. One line comprises a set of 386DX and 386SX CPU s; the other is a complete PC-on-a-chip. The latter combines fully compatible versions of the major system compo- nents C8086 CPU. 8254 timer, 8259 interrupt controller DMA emulator. XT bus controller. CGA graphics con- tnDller. and 16C450 UART) in a single package called the F8680, Building a system with the F86S0 amounts to continued on page 92 BUYER'S MART FOR SALE TUBES; oWest;' latesi. Parts and schemaiics. SASE for fists. STEINMET2. 7519 Maplewood Ave., R.E., Hammond, IN 46324. RESTRICTED technical information: Electronic sur- veillance. schematics, [ocksmithing, covert sci- ences, hacking, etc. Huge selection. Free brochures. MENTOR-Z, Drawer 1549. Asbury Park, NJ 07712. CABLE TV converters: Jerrotd, Oak. Scienliftc At- lantic, Zenith & many others. 'New MTS" stereo add-on: mule & vofume, Ideal for 400 and 450 owners? 1 (800) 826-7623. Amex. Visa. M C accept- ed. B & B INC., 4030 Beau-O-Rue Drive, Eagan, MN 55122. FREE CATALOG FAMOUS "FIRESTIK"^ BRAND CB AMTEHNAS ANO ACCESSORIES. QUALITY PRODUCTS FOR THE SERIOUS CB'er. SINCE 1952 FIRESTIK ANTENNA COMPANY 2614 EAST ADAMS PHOENIX, ARIZONA 85034 TUBES, new. up to 90% off. SASE, KIRBY, 298 West Carmel Dhve. Carmel. IN 46032. XV. notch fillers, phone recording equipment, bro- chure SI .00. MICRO THinc. Sox 63.6025. Margate, FL 33063 (305) 752-9^02. CIRCUIT Boards — Complete printed circuit fab- rication from single sided to produclion mullilayers. Twenty- four hour turnaround available. CIRCUJT CENTEa PO Box 128. Addison, IL 60101. (708) 543-0671. _^ PREVENT descrambler deteclion & damage! Order Tech'Block lodayl Simpla in- line connection. Only $19.95 PP.D. THE STAGE DOOR VIDEO, PO Box 518, Belleview, FL 32620. For C.O.D. S 1 (800) 395-4557. QualKy Microwave TV Antennas LIFETIME WAHHANTY WmaESS CABII ^ IFTS ^ MMDS - Amateur TV Ultra High Gihi 50(tbf+| • Tunulili 1.9 Id 2.7 Ghr » :^5.Ch^,-=^el System Complel* SH9 95 PHlLLiPS-TtCll ELEGTROKICS f^0. Box fi&33 - ScQttsdale, AZ m^t 1602) ^7-7700 Cnm m ptione orderil MailerCard: • Vlia • COD'i • Qunmnf friciig i e Q tr S6 ELECTRONIC supermarket surplus pnccsf Trans- former specials^ railroadors^ builders, engineers, experimenters, LSASE, FERTIK'S, 5400 Sla, Phi- la., PA 19120. OUR monthly picture flyer lists quatity surplus parts a! low pricos. Single and quantity prices. STAR- TRONICS, Box 683. McMinnviHe, OR 97128. PHOTOFACT folders under #1400 $5.00 Others 37.00. Poslpajd. LOEB, 414 Chesfnul Lane, East Meadow. NV 11554. (516) 401-4350. CB RADIO OWHERS! We specialize in a wide variety of tE?chnicaJ informafion, parts and services for CB radios 10-Meter and FM conversion kits, repair books plans, high-perfomiance accessories. Thousands of satisfied customers since 1976! Catalog $2. CBC INTERNATIONAL P.O. BOX 3t500RE, PHOENIX. AZ 85046 DESCRAMBLEBS Cable TV converters, iowesi prices, Quaranteed, best quality, all types available, CNC CONCEPTS. IMC. Box 34503, Minneapolis. MN 55434. 1 (600) 535-1 B43. TOCOM and Zenith "tesr^ chips. Fully activates unit. $50.00. Cable descramblers from $40.00. Orders 1 (800) 452-7000, fntormatJon (213) 867-OOBt. SPEAKER repair. All makes — models. Siereo & pfoSessional. Kits avaslabJe. Refoaming SIS.OO. AT- lANTA AUDIO LABS, 1 (800) 565-6971, REMOVE tamper resistant torx screws. Sol in- cludes seven VV bits. S29.95 plus S3.50 SSH. SUN- SET ELECTRONICS, ^2145 Alia Carmel Court. Suit© 250-139. San Diego. CA 92128. CLASSIFIED AD ORDER FORM To run your own dassifted ad, put one wofd on each ih« linca b«l<]w and Xhis^ lorm aFong with your check toi Radio- Electronics Classified Ads, 500-B Bi-Coun!y Boulevard, Farnningdale, NY 11735 PLEASE INDICATE in which category of classified advertising you wish your ad to appear. For special headings, there is a surcharge of S25.00. ( ) Plans Kits ( } Business Opportuniltes ( ) for Sale ( } Education Instruction ( ) Wanted { ] Satellite Television ( ) — Speciaf Category: S25.00 PLEASE PRINT EACH WORD SEPARATELY. IN BLOCK LETTERS. (No refunds or credits for typesetting errors can be made unless you clearly print or type your copy) Rates indicated are for standard style classified ads only See beiow for addilionaf charges for special ads. Minimum: 15 words. 1 2 3 4 5 6 7 8 9 10 t1 12 13 14 15 ($46,50) 16 ($49.60) 17 ($52.70) 18(SS5 80} 19(358.90) 20 (S62.00) 21 ($65.10) 22 ($68.20) 23 ($71 .30) 24 ($74.40) 25 (S77.50) 26 ($80,60) 27 (SS3.70) 28 {$8€J0) 29 (S89.90) 30 (S93.00) 31 {S96.10} 32 ($99.20) 33 ($102.30) 34 ($105.40) 35 ($108.50) We accept MasterCard and Visa (or payment of orders, if you w;sh to use your credit card to pay for your ad fill in the foEEowing additional tnformairon (Sorry, no teleptione orders can b6 accepted.^: Card Number Expiration D^le Please Print Narne Signature IF YOU use A BOX NUMBER YOU IWUST INCLUDE VOtlR PERMANEI^T ADDRESS AND PHONE NUIVIBEH FOB OUR FllES, ADS SUBMITTED WITHOUT THIS INFORMATION WILL NOT BE ACCEPTED. CLASSIFIED COMMERCIAL HATE: (lor firms or rndtvittuals offermq commercial products or ser^/ices) S3. 10 per word prepaid (no charge for zip code) ..MINIMUM 15 WORDS. 5% discouni for same ad iri 6 issues, lO''^ discount for same ad in 12 issues within one year- il prepaid NON-COMMERCIAL RATE: (lor individua's wfio wani to buy or sel( a peisonal tJemJ S3. 50 per word, prepa^d.. no mm i mum ONLY FIRST WORD AND NAME se( En bo!d taps ai no extra charge. Addiijonal bold face (nos availahio as all caps) 55c per word addltioraf . E:nt;re ad in boldMco. 53 70 per word TINT SCREEN BEHIND ENTIRE AO : S3.85 per word. TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD: S V50 pc r word EXPANDED TYPE AD: S i,70 per word prepaid. Entire ad inboSdface. S5 GO per word TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD: S5 90 per word TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AO^ S6 HO per word DISPLAY ADS: r 2 4 —5410 00' 2 • 2V4 --SBZOm 3 ■ S 3230 00 General Inrormation: Frequency fa'frs ,ind prepaymcni discounis arc avai1<5b3c ALL COPY SUBJECT TO PUBLISHEFiS APPROVAL. ADVERTISEMENTS USING PO. BOX ADDRESS WILL NOT BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLlSHEB WITH PERMANENT ADDRESS AND PHONE NUMBER. Copy to be in our hands on Uie fjth of Iho third month prt'COdiruj tho date of I ho issue, (i.e., Aug. issue copy musi be received by May Sih). When normal dosing dalo fails on Saturday Sunday or Holiday, issue closes on preceding working day Send for the classified brochure CircEe Nurnher 49 on She Free Infarmalion Card. DESCRAMBLERS TEST eqyIpmenC pre-owned now at affordable prices. Signal generalors from S50.00, os- cilloscopes from ^0.00, otfier equipment, induding manuals available. Ser^d S2,C0 U,S, ior catalog, refunded on 1st order J.B. ELECTRONICS, 3446 Dempster. Skokie. IL 60Q76. (703) 982-1973. DESCRAMBLERS: Oak Sigma, Varisync, Hamlin, Scientific Ailanta, Jerroicf, Pconeer. Sylvama Cata- log $5.00 moneyorder (cradiled first order), service manuals, schematics. SURFLUS ELECTRONICS, PO Box 10009. Colorado Springs, CO 60932. WiRELESS CABLE RECEIVERS 1.9 TO 2.7 GHz 30 CM ROC Am E UHA ,SYSTEM II 93 M 3D CM CTlYSTftL CONTIlDLUt} SVSltM 1?S4.95 suH mmmt.'ii m n . (hc. sch s si m P 0 . m tU 55? CATALOG Off TH [S£ mmi, n. zmi m other rm mi^m-Mii VIDEQ PRODUCTS DUANTITY DISCOUNTS YOI Like to go exploring? New ccmpuler maze game — Dungeon Thief, Simple, fun. for all ages^ abilities. Full game Si 5 00, demo S3 .00. PC's com- patibles, color or mono. Specily disk (5.25. ' 3,5") Chech/m.o. to: SENTE SYSTEMS,HJC., Oepl. 67. Box 9439, Anaheim, CA 92812. MASTERCARD AND VISA are now accepted tor payment of your advertising. Simply complete Ihe form on the first page of the Market Center and we will bill, ELECTRONIC test equipment and parts. Fr^e cala- tog. EF ELECTRONICS, Box 326. Aurora, IL 60506. DESCRAMBLERS, all brands, exampies Tocom VIP w/r S275.00. Oak RTC-56 w.r 10 (n Sa9 00, M-3 5-B S35.00 — 10 (o $29,00. FTB. 10 $59 00, SA3'B 10 f": $59.00, Harnlin CRX 6600 w/r 10 (Vi? $79.00, Svlvania 4040 DIC replaces Jerrold 400 DtC w.r 10 Ut S69.O0. full warranty CO.D. orders OK MOUNT HOOD ELECTRONICS, (206) 260-0107, Advanced solid-state LASER 0* **iv» 10% ^ . w »o* POLARIS rndustries Nl W Wicuta Hd.. iiiutc 3m ti AtUatti. DA 30342 f rfj ^>iir Ttii fn^f >iVnjf Offler i^rif 1-800-222-5620 TEST TURN-ONS SA 8580 SA B550 SA 8500 SA 8570/90 ZenttfT aEI Jerrold Starcom 6.^7 Tocom-VlP $44,95 each 1 pc boxos SA 85e0 Starcom 7B B Pioneer 6110 Tocom VIP S279,95 eacfi. 1 (800) 74- CABLE. CB TV Jerrold 450'DEC $45,00, JSX-DIC M35B or SB-3 SI 9.00. RTC-56 $79.00. Other brands in slock. For dealers only (405) 685'2048, TUBES. Thousands. $ .85. None higher, SASE for list. CHUCK ADAMSOM, 3410 Sands, El PAso, TX 79904, (915) 757-8609. CABLE TV EQUIPMENT CALL TOE FI^ 1-800-228-7404 aiRF90DUCI5« PBOOf 30 DAY mm M£ CAP}?/ All MAJOR ISANDS BEST PRICE BEST THE OlNNECnOM ton MORE tfO^MADON CAIL OR WRITt l-5im5031 #3CF eg. JW Auem tbcm 7ITW CABLE TV DESCRAMBLER LIQUIDATION! FREE CATALOGI Hamlin Combos Oak M35B S60 (niln. 5). etc. WEST COAST ELECTRONICS For Information: 8ie<709-1758 Catalogs & Orders: 800-628-9656 Ferro Fluid PfO'Toch torro fluid Is comrrxjnt/ usod on voice coils lo sub^taniially impfOvQ fioouen^y fospoi^se, f n cre«i.£« I rn ns lent and: con: i n uouS htinCiimg capabiiities and roduco second ajid third order harnwnic distortion, ti roduc&s tho 3.1 retsoaance wilhoi^l a signitioani reduction in S P L. f erro flu id can eHectlve!/ increase powof handling capability oi a driver b/tOO-300%, Goneral p u rpctse 1 iuid f Of two^ite^£ and mid/ an g es only. 1 0cc bciTtIo (SrtOugh tor 75' too twee! &r5) . #RM-340-430 $19^5 Each Light Oak Speaker Cabinet Premium poned speaker cabi- net made of acoustScal grade partide board and oav^to^ h a jjghl oak vi n /I iamin ass . Pr e- cut with an 1 hoie Jof use with rrast 12" wooiers. The baflie board has no twooler or mid range ho'o^ for ddsl^n fJox- biJiiy. Jh^ a'4" thick panels board ensures low pjnel reso- nance. Dimensions: 15'x 2r. Vobrrke: 2.5 cu f(. Grill and lernnJnal tndudt>d. Scid ifidividualV- $49- $45^° Each [2 up) #RM-262-100 12 Gauge Neon Wire Thocompe'itJon in today's aufo sound contests is so (kerce lhat good sound aiofie is not enough lo win. Wore and more installers are sulving lo make their instatEaEion more pleasing to the eye. Par{s Ejcpress now stocks 12 gauge speaker were In vibrant n&on ctslors, Tha wir o is the tame high quality, made in the U.S. wire you have used belors. but now 'A has 1 1 ashy, neon colored Insulating jackets. Available in neon pink, neon groan, antJ neon orange. SokJ by iho loot on or 50 ft. soools. #RW1-100-162 (Ni^on pmk) #RM'tOO-166 (Neon orange) *RM--I00^170 (Neon green) Tuned Port Tubes ThDS e attract Ive, pref ojvned [ Ljn.ed po rts zltoiN the back pressure /a- diated Ucm the fear of ihe woofer to reinforce the sound level En front. MaiJeol bfackpEasttc. 49** /FL Pan* Utnglh Difl. (1*9) ClO'Up) If RM 260-320 T i-7/e" ifRM.260'a2l 4- i.&a 1.20 JIfRM 260-322 5- 2' 1,65 1»30 #RM 260-323 r 1.40 J* RM. 260-324 5- 2-7/9" 1.B5 1.50 If RM 260-326 3' £■7/8' L65 1.30 (rRM.260-327 3-7/S" 1,B5 1.50 ITRM -260^326 5" 3-7/8" 1.95 i*eo No mixing lor quantity pricing. Famous Maker 3-1 12" Speaker Pair Djal cons 3-1/2^ speaker pa;r lor upgrading stock di:tsh sp«^akers. Graphite f its [pr composite woo!er cone provides a sr!rx>oih eI^tend&d response at ail power levels- The h igh frequency r adiator (whijzet) takes over Irom Ihe woofer at 6.000 Hz ant) greatly extends the ressjonse past 20 KHz. S[rcntium f err it© nnagnet. 3/4' high lemperature voice coil. Impodance: 4 ohm. Povwjr handling cafiability: 2S watts continuous, 70 watts peak. Frequency response: 120^ 2l,0ODH2. Equippe^lw:[h d;ist screen. Mada in Iha U.S. by a company wich over 40 years experience in the auto sound market. _ ^ N'^^ Pair #RM-265*275 Subwooferinput/OutputTerminai This recessed terminal pangl has inpuls lor right and lefl chaon^ts as^ll as. outputs lor rigt^t and bell channels to route to your satel I ite speakers. : G/eatly simp lilies suttwoofef tiook-up. /2 Reseda BWd., DepL2nO Reseda. CA 91335 EDITOR wi!h source $49,00 modify and sell alt you like. No royalties. Written in QuickBastc version 4.5. Manual on disk included. TARBELL ELEC- TRONICS, 6S81 John Avenue., Long Beach, OA 90805, (213) 423 2792 PLANS AND KITS FASCINATING electronic devices! Da^ers! Lasers! FM. AM phone Iransmitters! Dotectorsf Kiis, as- sembled! Caialog S2.00, QUANTUM RESEARCH, 16645-113 Avenue. Edmonton, AB, T5M 2X2. HOBBY broadcasting HAM CB surveitlance irars- mllters, arnplifiers, cable TV. science, bugs, other great projects! Catalog Si. 00. PANAXtS, Box 130- Ft, Paradiss, OA 95967, DIGITAL recorder. Dtgitalty record any audio source with special effects. Microprocessor con- trolled device. Detailed plans, S975: T. ZURAW, Box 34 L Dearborn Hts, Ml 40127. BUILD our picture only, satellfte TV descrambler for most channels. Uses 6 transistors and 4 chips. Most parts from Ftadio Shack. l=or educational purposes only, not to be used i I legally. Circuit board and plans S30.00 U.S. funds. Circuit board, plans, arid parts kit 389.00 U.S. funds. Build a super high economy carburetor, to make eight cylinder engines run on less than one gallon of qasoline per hour. Plans for 5 types S20.00 U.S. funds. Cheque, money order or Visa welcome. Order from VALLEY MICROWAVE, Boar River, Nova Scotia, Canada BOS 180. Tel, (902) 467-3577 8 to 4 eastern lime. Fax: (902) 467-3937 anytime. INVESTIGATORS, eKperi mentors — Quality new plans. Micro and restricted devices. Free catalog, Self addressed stamped env^?lope required KEl- LEY SECURITY, INC, Suite 90. 2531 Sawtelle Blvd.. Los Angeles, CA 90064. REMOTE CONTROL KEYCHAIN ^REMOVE LEAD VOCALS ^From Rtcords & CD s Sutid kit br ix\.4tt i&> w^ior elef»o records. COs. tapK cr FM bfOadcB^b. connects to any ti(jn* oofnponent stereo. Perromi lAffl w^lh tfi» tJeckgrouTdfi. Yau cam b* n« Fftsd gingw of ycv fstfcrltf Woeder Tech nclog res 14773 LiiKJaoy Rd. Ml Offlb. Ohio 45154 j VISfTECTtNC- (510) 531-8425 Completer 'mi rti-^ranBmUttJr and +5 vdc RFrccctvOr Fuliv ct$BE?mbtcd incEucflng plnrw fa buiEd your own auto ^\itm Ouontity disccunts av^il^tj^c on A O £r Check^Vis^ or MC 5>^'t.yp Add S3 shipping Box 141SS, Fremor^t; C^, Fax (5t0} 531«8442 REMOVE VCR copy protection. PCS PAL insiruc- lions 316,50 w P5.H. LOGtCAL CHOICE, 955 NW OgdcTi, Bend OR 977Q1. BUG, telephone, FM, plans, Converl RadioShack device, easy, St2,95 ALLAN LABS. PO Box 14302, 101 AHan Lane, Research Triangle Park, NC 27709. PRINTED ctrcuit art work. Low cost, for free infor- mation write NEGRON ENGINEERING, 159 Gar- field Race. Brooklyn. NY 11215. Fax or calE (718) 768-4026 VIDEOCIPHER l(/scanner.cable/sateilite modifica- tions books Catalog — S3. 00. TEL ECO DE, PO Box 6^26 RE. Yuma, AZ 65366-6426. DESCRAMBLER kits. Complete cable kit S44.95. Complete satellite kit S49.95. Add S5.O0 shipping. Fft^o brochure. No New York sales. SUMMIT RE. Box 489. Bronx. NY 1046S. PCB and schematic CAD. S195.00 IBM EGA CGA Multilayer, rubberband, aulovia, NC drill, laser, dot matrix, plotter, library, Gerber, AUTOSCENE. 10565 Bluebird St., fVlinneapOliS. MN 55433, (612) 757-8584 tree demo disk. GREAT value. Precision fulty- re gu fated supply f2 + i(0-50V K'O.01%5A0,5%) and (1+X5V-3A). Tested parts as specified Radio El. fv1ar. 90. No case U.S. 3560.00 - S20.00 shipping (U.S. Can) cheque or M O. to: BCH, 150 Clark Blvd,, DepL 299. Bra- malea, Ontario Canada L6T-4Ye. OAK RTC-S6 99.m M35'B 29.00 TocoKf ma JIT PRooi tfsj aiip .^^ rw m nxr>A4 S5ot VIP 2^iifHf 5^ J A im oo tlAMUK JiiMROLD. 71-NlJil A. A IJOW A% l^.CHf M-f' 6A-3P PST. 1-800^622-3799 SAhfE DA r SiUmNG. FULL WAkRANTY a DESCRAMBLERS Conveners, Rcmnte ConiroK, IX^'^cramhlcrs, mors AH major brartds carried *JERROLD, *TOCOM, *ZENITH ^GENERAL INSTRUMENTS ^SCIENTIFIC ATLANTA, *OAK *HAMLIN, *li:AGLE, *P10NEER 7 th Year in business. Thank You Member of Omahii Chajnbcr of Commerce 1 Ycaj warranty on new cqutpmcnt 30 Day money back guarantee Orders shipped from slock within 24 hours CALL TODAY FOR A FREE CATALOG 1-800-624-1150 3 CCD, % ^> 875 so, 72nd St: 89 CIRCLE 53 ON FREE rNFORMATION CARD Cable TV Descrambler Kits Universal Kit..,. .355,00 Includes sii pans and PC Board. Hot inctuaeo i$ ine ac adaptor dr enclosure. Tri-Mode Kit„»„.„, ..S39.00 includes p^Jis PC Saard and: AC Adapter. Not tncJuded is \r\^ encEcsure. SB-3 Kit S29.00 in£iiua«$ ail pans, ?C Oo4^rd ana AC Aaiipidr. Uoi Universal Tutorial ..,„.S9.95 includes an iri depin sEudy cr the tecnonotogy used ano has iroudEflshodtir^g hims. Tri"Mode Tutorial S9.95 tnctudes a Qaie Py gate study ct trte crrcuit ana iMki ErouDia^riooting mnts. Call Toll Free 1 -aOO-258-1134 COD Only M & G Electronics, Inc. 72 Orange St., Suite 216 Providence, RL 02903 SECURITY system plans for eight zone, entry/exit delay, prealarm contrailef witti independent tamper' fine 2 ones. Build it yourself tor under S50.0O1 Intro- ductory offer also includes plans to modify a readily availabfe product into an inexpensive alarm syst^^rn motion detector. SI 5. 00 ppd. V-TRONICS, PO Box 177, Ruby. NY 12475. PLANS^ New 150 watls audio amplifier SC compen- sated with power supply. Send SASE and $10,00 to lOVATION, 21 Tennyson. Dover, NH 03820. ELECTRO NiC projects — Complete ptans parts list, Audio.'autoniottve Eritrared magnetic, power.' phtotograptiic/custom designs.computor programs, Caialog S3. 00 credit 1st order. ULRICH ELEC- TRONICS, 11625 Jefferson St. NE. Blaine, MN 55434 BUILD 6 simple low cost circuits to extend the func- tions and ranges of your meters and scope. Easy to build, useful f Send now for complete instruct ions ► S5.00 BLUE BELL DESIGN, INC., DepI REM. 524 White Oak Rd., Blue Bell, PA 19422, INVENTORS INVENTORSI Can you paten I and proltt trom your rdea';' Call AMERICAN INVENTORS CORP, for free fnformation. Serving inventors since 1975. 1 (800) 338-5656. SPECIALIZED SECURITY SURVBLLANCE — Audio Vidoe.'infra rod. person- al protection equipment. Public, private, corporate uses. Extensive book: S9.00. Was Security Sys- tems" cataFog. TRI-TRON OF ATLANTA, 1857G Fox Hollow, Lilburn, GA 30247-3363. SATELLITE TV FREE catalog — Lowest prices worldwide. SKYVI- SIDN, 1012 Frontier, Fergus Falls, MN 56537. 1 (800) 334-6455. (See full page ad the Shopper sec- tion) CIRCLE 197 ON FREE INFORMATION CARD SATELLITE TV — Do it yourseEf — systenrts. Up- grades. Parts. Major brands discounted 40% — 60%. We H beat everyone s price, L.J.H* INC., call Larry {609) 596-0656. FREE CATALOG! 1-800-648-7938 JERROLD HAMLIN OAK ETC CABLE TV • Spedaf Dsafer Prices! • Compare our Low Ratait Prices! • Gua/nnts^ Prices 4 mrrmrti&s! • Ofders Shipped Irr^m&dimty! REPUBLIC CABLE PRODUCTS, INC 3 4C80 Paradise Rd, #15» D©p< flf i93 m 3 Las Veg&B. NV 89109 tllJ For al other intgrnaiion (702) 362^9026 CABLE TV Secrets — ihe outJa* publication the caij:e cofnpanies tr>ed to ban, HBO. M<^ne Channel. Showtime, des^amtilers, converters, etc. Sup- pL^ars list mdlldeciSS^- CABLE FACTS. Box 71 1- R. F^taskata. OH 43062 SECRET cable descf ambler. ByikJ your own de- scrambter tor less than $t 1 00. an seven Msy Steps Radio Shad« parts list irKlii6e6. Also Um descram- bfing methocls that co st nothing to try! Sond $10 OQ to: CdUIE WHFTE, 2 Marfin, Baytowm. TX 77530. BUSINESS OPPORTUNITIES YOUR Gwn radio sialic nf Licensed unlicensed AM. FM. TV. cable. Information SI 00. BROADCAST- IMG, Box 13Q-F1. Paradise, OA 95967 LET ihe government finance your small bustness. Gran (a loans lo 5500,000. Ffse rscarded message; (707) 449-fl600. (KSI). EASY workf E3tcetlenl pay* Assemble pmducts at home. Call loU free 1 (800) 467-5556 Ext. 5192. FREE CATALOG ■ CABLE T,V, BOXES - ALL TYPES - - LOW PRICES - DEALER PRICES ^ HOME assembly work avai Cable! Guaranteed easy mor^ey! Free details! HOM£WORK-R, Box 520. Danv^lCe, NH 03819. WHAT snow^ For sate: ihnvir>g, fulty equipped, ai^ dky video lepaif shopi Proven -tO^'^ - inoea^ tn net last three years S70.0OQ.00 cash. AUDIOTECH, 256-6 North Hjghvt^y 101, Enonrtas. CA 92024. FAX (619) 944-0345, Phone (619} 944-9048. CABLE TV "BOXES" Converters-Descramblers Remote ControlS'-Accessarles * Guaranteed Best Prices * ♦ 1 Year Warranty - C.O.D/s * ♦ Immediate Shipping* * FREE CATALOG * CM\ 01 Writ* HAS/TRANS-WORLD CABLE CO. 3S58 North Uk6 Blvd. ♦ Suite 255 UkePark. Florida 33403 1^0^42-9333 1-600-848-3997 MAKE SSS! Become an Amencan etecsronics deal- er^ Profit opporiymiies Since 1965 Call SCOTT PRUETT, 1 IBOO) 672-1373. MONEYM AKERSI Easy! One man CRT reduikJiiig machinery S6.900 00 rebuifl. SlS,9O0 00 new ORt 1909 LOuise. Crystalake. IL 60014 t8:5^ 459-0666. FaJ(f6t5) 477-7013 CABLE DESCRAMBLERS OAK M35B COMBO S39.SS Jerrold. Zefiitb. Hamlin. Sci. Ailania. Pioneer & MORE! OUR PRICES ARE BELOW WHOLESALE! CABLED PI-U8 1«17 Chase St. *4ei-A Panorama Oty, CA 91402 1-600^22-9955 • Other Info, 1^16*765^500 NO CALtP SAlfS " DlALEflS WW TIP ELECTRONIC ASSEMBLY BUSINESS Start home spare Ume tnvcsimenl krxM ledge ot ejioenence unnecessary^ BiG DEMAND assem- Cling e'ecirofnc devces Sat«s handled by profes s cr^a'S Unusuat biiS'ness opportun ty FJ1EE Completf itlii^nted titer^lu^e BA^rTAREOOBuxa-te ANTIQUE RADIO CLASSIFIED Free Sample! 0^0^;^}:'% Antique Radio's iM^^^j^^J^^^^n - Largest Circutaiion Momhly . <^ r jj Articles. Ads & Classifieds. ^i^^^kU 6-Momh Trial: 515. 1-Yr; $27 (540-15! Class). A.R.C, P.O. BoJt 602'L9. Carlisle, MA 01741 AAflRK V CLCCTRONICS, INC. Competitive Pricing ^ Fast Sliipping Since 1985 IN CA V80D'5Z1-MARK (orders onty) OUTSIDE CA 1 -li)0'42a-FtVE (orders dniy ) ORDER 6Y FAX (Z13) SBa-BB&B CATALOG & IMFOflMATlOH (213) ZUMZB A indicates Iho revel of dinicutly in the assemblirtg o1 our Products. A Qcginner aa fintcrmedlalo AAA Adva nced * FuHy Assembled ^^^^ . . . ' rA-477 V* " , , . . TA 1500 Special offer will be given to the purchase 0( AmpUfier + Metal Cabinet Power Trarislormen ta 3600 . ^ AMfUFIEIIS KIT MODEL 0£ICf)lPT|(]J« 1 h- ?aWK? 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TA ■ 1 000* t*- ! J M a^QO:JtMV[)C CWCltl>rUA|0(^. lA 1300 taflil Ft(|i-itar SifwH VQl ^^!^t^pHTA J6« ?A r* inw. TA-12WM?( Alps fln:n!Dr UujI CgnirDi (Ta .jtm r.\ .^0.- FA a co naiMATons tU i^t! 3A flt^M DC S^jwf 5«f«^ ( * 16 75. 121 METAL CAflWEn WTTH UUHntUII PHa MOOEL r 1 W I (T KUrCHlHC tG-ifiS4 4* ir r rA ta-uta ta ttqo LC-1«i 4- I* ! l f TA^rr TA I3S TA lA TflOCA TA 3*00 2»* l^ r 7A JJfA Ti ■! 7m TJ, TjtSHUi * pnicf trie »50 »I]0 IMMKl «r rAIO^Uti tA tt3 TA.IOOOA TA IMO 3ni73A rn 10] rA-tejA ta4oo taioo u vu on 4mi}«A rA-irt GQC 2ti%2tA rA m nViIJA OH iMTillA ■55? 1 7 *i P«iC£ 3100 «30 1Av■icIi:<^-^«(F{>1>ofC*« iHtaiMf aanOitcMinrCO O O4nCa0' ' 1 4 la An "v^^ *fL4M^ w AtcabH ««ian '^A^ i^^^m^** BuiMini i SliowrDom ricm: {PMstc: Twnei M^mtvtm^ MonthruFti. 9^:30 am. to S. DO pm Sat lOOOanriD^eOpfn o o MARK V ELECTRONICS, INC. - 8019 E. Slauson Ave, Montebello, CA 90640 B H CIRCLE 93 ON FREE INFORMATION CARD Your Natural Resource for Widi Test/Measurement and Prototype Equipment Jameco Solderless Breadboards for maiU' kiiut^ oj prnmsypint; ."ui nruELi Jt-sipi, [..ii;i;lt mmli'K iatitrL^ a .h^Livy-Juty jlumLJiuni kKiciMc with voltjj^c .imi i^rouisiJin^ [Xksts. Pan Dim. JE2! XlHxlM^ JE23 e-,SUx2.l2^ JE24 6.S(U3J2'i Contact Binding $4.95 6.95 12.95 Ointict Bindiftg Po^i s Trie Am JE25 JH26 JE27 Uf>Wl 17.95 2s.VX> 4 22.95 ^Jm ^ 3L95 GoldStar 20MHz Dyol Trace Oscilloscope Tlu' ptrltxt unit ftn [r>day\ tcjitiup and mwiurcmrriJ: CR 7" di-^pli^v, and bifidwitlih fmiii DC to 2Q MH/. l lie- WLih [wo 'iOMHj: ]irc*E>OH twcj Jii'-L"'*. fH>^^ [.'I t t)id. i9pi:::j[ii>ii sskiTui.il, si-hcmjiLL^ J ltd lilock jEui wiFEEif; diji^ruiJiL It's Liiu] |i()rf.d)lL' wiih Li two-vor svjrriiinv. » ..,.5399.95 MAinv Bid BNC Cable Assemblies for G57020 BNCl B.N<:fMj lo BNCfM) lUnS A/U ...$3.95 BNC2 liKQM)ioMicrEf}l(«jk mmyriu.,, 3.95 BNC3 HNQM} to .Micm i IrtoL [Un74C3rL) 3.95 JAMECO COMPUTER PRODUCTS lA Ht)iir Toll-l-reL' Ordt r Horlint.' 1 •800*831-4242 Weller Soldering and Desoldering Stotions m a: iMMC l^lca.sc refer lo i Mail Key 2 | _____ wlien ^^^^ ^ oriiering - ' wc:c:ioo * Tcin}K'fiiurc jdjuitjblc from JSO"" * Zero v ol ripe cirttiii prorects sen^iutv e * 1 EiJitL"d e)rl/()ft\w:irch WCCIOO .^cddcriEif; S(:ituH)....S89.95 * Si) Watr IVmperatureConirotled * ni'MjlticrriiiL; kvid is icmjicrjtuu- Lojtiiolled m * Low nuirticnanu vajcuum sysieni I DS600 lXsr>UkTing Siaiton ..$549.95 • Handheld, high aauMC)' • AC/[K] volrj^e, AC/IX^ iJiirrtfiti, resistance, diodps, afiHiciuiry, [fjjuistor hFH ■ M-inual ranging w/ »vcrIoati protKiion • t 'onies wiih proki^, baiterics, Oie And tnafltiil M3650&M4C5aonly: ' Also measures frtN^utiicy juid cap(icit.ir5t.'e M5800 3/* [>i3;ii MuJimuu'f ...... .539.95 ^ M3610 r S [ Srjiir MuJumcitf S59.95 fii t:.ii?.ii;ir:jnce ,....$74.95 M4650 -i I iiuii w/l -rci^ucnty ( '.JpJciTJnl.^ ^i Ujm Hoiaswiith 599.95 Jomeco Logic Pulser Jameco Logic Probe *t:umpanb[eM.iih Til, DTL RTI., i ril, HNILMOS and CMOS la • INUi Sy-nc input imju-dance • ['ulscr iiiodt output currt nii lOinA * Square wj%x- ciirrtnt outpur; TinA • Audible mnv LP540..... ..516.95 A*R.T. EPROM Programmer • Progriin^ ail LUirtni KPROMi in (he 1716 to ring;e phis [heX^HCn O IMU)M * port • SoltWijre trjeludcd EPP SI 99.95 * M rctpttncy H( ) M I { * M in mm iti ' dcrrctahl c pii I Si' ; 1 0 us * 1 2 1) Kil in put iiTilKdaoce • Mjk, HUppK voliiE^e: i25V - Ti l. ihieshoy,' (J^.)*f);s\^i«J V. iHi} +2.>V lOJV • CMOS ifireshold: (U) 3^ vcct30%.(}ii) 70';MVt:aia% MS 104 $24: UVP EPROM Erasei • V.^i^ jII Hl'K(}\t \ - i r iies I thi[» in : 1 5 miimies and 8 thifis in 2 1 nliii * UV Lii[ftuity: 5K(H) L)W/CM' DE4.. ,„SS9. EPROMs - for your programming needs Part No. TMS2516 54.25 TMS2532-35 8.95 TMS2532A ..,..,,..6.95 TMS2564 5.95 TMS2716 5.95 1702A 3.95 2708. .4.75 2716 .3-39 2716-1. ....,3.75 27C16 .....4.25 2732 4.95 2732A-20..... 4,49 2732A-25 ............3.49 2732A-45 .2.95 27C32 4.75 2764-20 $5.95 2764-25-.- 3.75 2764A-20 ......3.75 2764A-25 3.19 27C^4-I5 3.95 27C64^25- 3.25 271280TP.. 3.49 27128-20 ...7.95 27128-25.. 7.75 27128A-15 ,.4.95 27128A-20 ..4.49 27128A-25 .....3.75 27CI 28-15 5.75 27CUS-25 7,95 Price 272560TP .S3; 27256-15 5.- 27256-20..,. 4; 27256^25 4v 27C256-I5 5; 27C256-20.. 4. 27C256-2>„. 4. 27512QTP. 4 J 27512-20 ...6; 27512-25 5,' 27C5I2-I5.,.».»..6j 27C5I2-20. 27C5 12-25 ....5J 27C010-15 9J 68766-35 6,! * Partial Listing ' Over 4000 Electronic and Computer Components in Stock! 00 CIRCLE 1 14 ON FREE INFORMATION CARD election & Competitive Prices Computer Products and Electronic Componetits seinble Your Own Computer Kit! Jaitieco 1 6MHx S0286 Coitipittor Kit di 1 henrt tiii(lmiJtt]Jiit| of component d ihdr fisnctwm ndrpih j^H-mKly iftiimciiiiim LnduilnJ nnini; in All cvfiiirii;, utingcomitum mjoU Itw^rc itklijJcd 2S6-!rV MniltatiK>jtil wtih 1-kcy mh.iMLri! kiylKVird Lilii IM'H '.m J oNitrallcr ppy dck dtivc hv suid Jblctop OUT 11 iiLipTJml:ii loJlvijff Joifieco 4-€hantiel Switching Power Supply *5VDC -SVBC ^ LOA , ■: ♦UVDC ^ IjOA ' >-¥>>i).Km'At:*^47^4Ui1z • Diu [milt led PCS604A ,..,»„.„..S44*95 Adilitivtu! P0U^SuppUes dvailahle! Zalson 56 Watt Swltcliing Power Supply I tSVDC ^ tIZVDC ^ -I2VDC @ 4.5A I.4A 1*2A 816... -S599.95 * Input. mvAC^rr MnHi " Two4piitrtKi(Qmk;a>anc«dfifo^ • Wci^^hi LSlbi. PS6I4I . Integrated Circuits* No. 1-9 10* 3-.. — . *S-29 SA9 1 29 ;19 * 29 J9 J5 ^25 7 35 .25 i 35 .25 '3 -^^******»rm**9**t**t*** *29 *I9 29 J9 I 35 25 7. 89 J9 i * 39 *29 1.. 45 35 i ....45 35 > 2.95 2.75 } .».59 .49 n .49 39 H 79 .69 15.... 79 .69 Linear ICs* So, 1-9 10* 82CP -„...„^...,.S.59 S.49 Urr .65 35 i24N 35 .29 136Z 1.05 .95 t39N ^ ... 39 35 55V™ .25 i56N «... 49 39 ■23CN.. 49 39 -4ICN ,.29 .25 45SN 35 .29 4«8N ......45 ..^9 .489N.... ,....,..,45 .39 J2003A..,.. 69 .59 fc9l4N J 95 1.75 532 1.19 1.09 5T ....................... .45 .41 IT ,45 .41 Dynamic RilMs Part ?w>. l>CHril?lii?Il Hrwc 4164-100 HHIm.MKi 1 $1,S9 4164-120 i:(lm.C>4Kx I 1.69 4164-150 l'>()m.64K % 1 1.49 4 1 256-60 fiOii V. 256K IS 1 2*49 41256-80 KOm. >V>K x I 2,19 41256-100 ...Hll)nv, 256K x I 1-95 41256-120 ...12nii^, 2V>K x \ 1.79 41256-150 ..JSniis, 256K3L I 1.69 51 lOOOP^SO... Hihis 1 MB K I 7.25 SllOOOP-10. H)(hl^. t 6.75 Misceiiaiteeus Components* Potentio meters \'itut^ ii^iilj^c iiracst nhnu tniii apace ^tMl [K,>K. lOK. i<^K, IDOK. IMF<; 43PXX 3/4 Wju. J S ( urn ..... S.99 63rXX 1/2 Wjit. 1 Turn 89 Transistors And Diodes PN2222 S.12 IN?5I SJ5 PN2907 ,12 C106B1 .65 IN4O04 JO 2N440I .15 2N2222A .25 1N4148 .07 1N4735 .25 2N30SS .69 2N39(^4 .12 1N270 .25 Switches JMTl 23 Sn > H >ii On 1 1 ty^^} MAS 206-8 srsi; ifi.piii am'i . 1.09 MPC121 mn. On i m i >ii ( to^ki ...... 1.19 MS 102 Srs i\ Muniffiun [lVh'BiitMn> 39 'AfMiStOHid iimfptititnt-i itiaiLible Connectors Part No. Ddctifwiofli DB25P S.65 DB25S ririiijlL\ 2S'pm .75 DB25H 39 DB25MH Metal { IfHKl 135 LEDs XC209R S.14 XC556G .16 XC556R .12 XC556Y l"l .V4, (VVltiivv) J6 iC Sockets 8LI> $.10 8WW' 5.49 14LP .11 14WW ,69 t6LP ,12 ,79 24LP .19 21WW 1.15 28LP .22 28WW 1,39 40LP .28 40WW 1.89 24'HoLir Toll-Free Order Hotline: 1 •800* 83 1-4242 Gill or Wrire for a FREE 90-Page 1992 Catalog! 530,00 Mlttimtim Order • l)ji^ Shircts - SDc cjck J AMECO COMPUTER PRODUCTS 1355 Sharcw^y lioad Hdmoni, 0\ 94002 FAX: 1 •800*2.17 -6948 BBS Support; 415-637 9025 ► Credit Dqi^rtiticiit • All Other Inquiries: 415-592-8097 ■ 7 AM - Sl'M r^,T. 47 mijoimm tm 1^55*3^ nA Tcrm^ Prices **!hi*T^t itt Llurtjje wiiJ-njui nutn.. l\mt|^tr Ifu id tmnt^wjiiTJiitiri it jT'iibbk- JO a, o CIRCLE 114 OH FREE INFORMATtOK CARD 91 CABLE TV DESCRAmLERSI CABLE KINGDOM! *JEROLD* *OAK:*; *HAMLIN* *ZENITH* ^PIONEER* *SCIENTIFIC ATLANTA* IN STOCK MONTH WARRANTY i UE SHIP CODi ABSOLTLEY LOWEST WHOLESALE/RETAIL PRICES' J -P , VIDEO 1470 OLD COUNTRY RD SUITE 31S PLAINVIEU, NY 11803 NO N-Y. 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Voi ce/Faj( 171 6) B74 -2003 COMPUTER CONNECTIONS continued from page 85 adding some SRAM or DRAM— that's it. Who wants it? In the era of $2000 386 boxes and $3000 486 boxes, who cares about a CGA-leve 8086? Makers of laptop and hand held devices Ike HPs 95LX. That's the theory, anyway. It may be thai we"re about to witness an explosior of PC Gadgets, miniature DOS-lik€ devices that surpass calculators arc the Sharp Wizard type of device. The other line consists of 386 clones thai provide 10-15% better performance Both lines incorporate a new tech nology called Superstate that pro vides an interrupt fevei higher than al normal IRQ s and the NMJ. and which when entered gives a totally new ad dress space for executing code. Su perState could be used to implemem power management functions, to em ulate missing instructions (e.g., 28€ continued on page 96 EASY ORDER 1-800-582-4044 EASY FAX 1-800-582-1255 line ueanoNiCS souacc TRIPP LITE - PRECISION REGULATED DC POWERSUPPUES smplete Line of DC Power Supplies to Convert 120 Vac to 1 3.8Vdc ±0.5Vdc. mdard Features Include: iid sisas mtegraK^d orcutt provides exoeflem regutation ttgm vdHaga maimajn^d up to 95% of no load value 3*1 Ciiia% fitiefing for khw no4£« opera^n avy (JLrty power ifartsrorrnef lor compJeie hne (solation I Off indfcator itgh^ arHj rugg^ ort off switch on faceptato :ondLJ«or grounded cord on TO Amp and larger models rrent limiting okKiifonic folcback for auio overcurrent proiection ACTIVE COMPONENTS :^ UtB DC Power Supplies Aw Designed For R^HBbiHiy and Superior PBtformancB^ ICS* Continuous Ripple (amps) Duly (am ps) F using toitage^ 4.S 3 .. Jntemal 0.1 Volt Max 3.125 x 4 7D x 0.25... 5 lbs. ler# Price 32.9S 44,95 64.95 89.95 126,95 179.95 249.3S H^VVxO (Inchee) Wejght 7..„ 10.... 15... 40,.. 60 ,. ...5... ..7,5 . ...12.. ..20.. ..32.. .......Chassis Mourn . Oiassts Mouni , Chassis Mount . Chassis Mounr . .0.15 VoJt Max. .0.15 Volt Max. .0.15 Volt Max, .0.15 Volt Max. ..Chassis Mount 0.15 VoU Max.. . 46 Chassis Mount 0.15 VoJl Max.. ermittant Communications Duty (SC*^i Duty Cycle) 3.75 % S.5 X 7 5 7 lt>S. . 4.5x6.625x7.625 10 tbs. ..„4J5J(7.5xa.2S 13 lbs. ..S.l25xt2.5xi0.5.......,201t)S- 7.25x12.5x10 26fbs, ,3,5x12.5x10,. 29 lbs. jSOLDERLESS PROTOTYPING BOARDS tures lof coof^ftatss fof dasy rscp^nitcfi eftiOflWt: 2O 29AWGj0 3 -O.8mm) er irtsafHon cycles ^epls al standard components 3 - 0-8 mmj ^^m^^J MICROS Order* Price .. . B.95 2.95 6S22A 3.75 6S21 - 1.75 6845 2.4S SOSOA 5.75 e085A 2.95 80S6 4.45 80SS 4.25 8237 A5 4.15 8250 575 8251 A 2.25 8253-5 2,25 \ 8255A5. 275 8275 18.95 I STATIC RAMS | Order # Price 2101 1.65 2114125 1.39 2147-3 3.75 6116LP3 2.75 6116-3 2.25 6264LP10 4,95 6264LP1S... 3,ft5 S264-10 4.75 5264-15 375 62a56LPlO,.. .6,75 62256LP15 6,25 62Q12BtP0 34.95 628ia8LPl0 32,95 Order i MK4027N2 411&20 4415*12 4164-10 4164*15 4154-20 41464<12 41256-80 41256-12 51258-80 514256*10 514258-80 511000-80 511000-10 511001^80 Order # □RAMS Price .75 . .85 . 2J5. 1.9S.. 1.55 1.25 275.. 275. 2.15 Desc^ ,....4x1 ...16x1 ....16x4 ....64x1 ....64x1 ^.64x1 ....64x4 ..256x1 ,256x1 4.95 256x1 6.9S.. 256k4 9.95 „E56x4 7.25 1Mx1 6.9S ...lMx1 0.25 „„,..lMx1 EPROMS Price 270S 2716 2732 2732A25 2732B4S 2764-25 2764 A25 27C64A15 27128A25 27256*25 27CS12-TS 27C010-I5 27C020-15 475., 3,45., 3.95.. 3.45.. _PfQ2t. .25V ..25V ...25V ...21V 4.25 ,„..12.5V 375 .,21 V 3,25 12.5V 3.95 12,5V 3.95 12.5V 475 12.5V 6.95 12.5V 9.95 .12.5V 2435 12.SV UNEAR Ortfere Price Order # S81G60 Price Pri(^ Dimensions (in.) Dist. Disl. Terminal Terminal Bini t en Z&40t3 tS. Z»«CiaCt5. Z1018Q, ZBQI&I and 2280 ^ f Z2480 13,9$ Intelligent Peripheral Con&oliers . -Weight: 2 lbs. tacom ICS 70O pagn o< tiau iriMCi and other lecMaf Bifbrmasoo on £iogr« O^ni C omi mif ii ea aiMs Cs, numbers contMd m tfni boot mm Zt6C3a3f 333S50. 25300. Za^30. ZeOCSO. Z9SC3Q. Kl. Z8S30. ZaOlBI. 214013. 2S4015, ZB4Ct3. Z&4C15. Zi440. Za4G40 amf Z35C80. Ms* ded are ajpptiGiiQn n^Mn- &r# 22503 13.95 D alacom ICs >»...».>...>>..».>.»^Weighl: 2 ibs, ^rocontrollers 1300 pai^t 04 (laLti t^hiKrl$. jipplicaljon nctes and leciinica) information on Zilog's frbcroconlrc^Sefs. p^rt numtreis conrndftOd In this bQak are ZSeOO/Ol /02/03/O^n 17t 2^1 3^71/61/32^1 . ?a'Oi zeec^Kj coacoacos c i oc i a.c i s C20 i /C27.'C30C40 cso ce t ess C9af Cg3'C94 C95 C97, Za6EOa.El9^E2l.E3aE40. ZMCOO. ZB5127, Zm%2%. Z765A. Z53Bfl awj :m ^ & 28275 16.95 Microcontrolters ..Weight; 3 lbs. joks are not relurnable. We carry the newest versions avaitabfe. flMOlfCrgQNfCS SOURCE 2917 Bay view Drtve Fremont, CA 94538 1-800-582-4044 1-800^582-1255 1-510-770-2346 1-510-770-2345 Spill tPST)/IOtt'apTED CABLE-TRONICS, INC. 1304 AIgi>nqui» Uoad Sui 1^501 Algonquin. Illtnoif; 60102 Does Your Heart Good. ^American Heart Association CIRCLE 1D7 ON FREE INFORMATION CARO } MONITOR TESTER continued from page 49 16 by IC5 to produce a horlzonts sync of 21.94 kHz. Vertical syric is generated by di viding the horizontal sync by 6-= at IC8s 90 output (pin 10). The qi output oriC9 connects back to itj own CLR input via ICG pins 6 anc 7 causing 1C9 to divide by 6. for ^ net division of 384. That gives us a vertical sync of 57.14 Hz at ICQ'f QA output. That QA output is con nected to IC2-e pin 11, which k configured as a one-shot, anc outputs a 60-microsecond nega tivc pulse to IC7 pin 13. The pulst is output at pin 12 of 1C7 which Ij connected to pin 9 of connectoi JL Switch S3 routes 35 LOS kHs to the low-byte RGB inputs of ar EGA monitor. That causes the monitor to display a pseudc Ihree-dimensional pattern to dis* pJay on the monitor As a few final notes, VGA RGE inputs are 75'Ohin impedance. Resistors R7-R9 reduce the am- plitude of the color signals to 0,5^ volt p-p. 400-line operation is produced by making horizontal sync negative polarity and ver- tical sync positive. EGA monitors switch from Mode 2 (enhanced] to Mode 1 by changing the polar- ity of vertical sync^ in Mode 1 it's positive, in Mode 2. it's negative. Construction The use of perforated con- struction board and wire*wrap is recommended for this project. Tty to keep the TTL clock os- cillators (OSCl and 0SC2) as close to IC6 and IC7 as possible. Also, decouple all ICs and the os- cillators with the 0,01 ^lF ceramic disc capacitors as shown in the schematic in Fig. 1. (You can sol- der them directly to the V^c and ground w^ ire- wrap pins). This project requires -H 5- volts to operate. If youVe already got a suitable power supply you can use It. Othenvise, Fig. 2 shows a suitable one for the project. Once the circuitry is com- pleted, you should put the as- sembled boards in a metal project box and tie earth ground to the case. Figure 3 shows the authors completed prototype, R-E €ORI\ ELECTRONICS too 10 Canoga Ave.. Unit B-S Chatsworth. CA 91311 LASER DIODES SINCE 1983 — YOUR LC. SOURCE — AND MUCH MORE!! NO SHIPPING CHARGES ON PRE-PAID ORDERS!* NO CREDIT CARD SURCHARGE! SCHOOL RO. S WELCOME! LS3220 LSOX2 ma. TOSHIBA TOSHIBA TOSHIBA TOSHIBA TOSHIBA SHARP WAVi- OUTPUT LENGTH POWER 6«0 nm 3 mW 670 nm 670 nm 670 nm iSJQ nm £70 nm 7tO nm 3mW 5mW SmW 10 mW 5 mW OPER. CURR. 8S mA 8S mA 80 mA SOmA 4gmA aSmA 6SmA OPER. PRICE VDLT. 129.99 49.99 59.99 69-99 109.99 79.99 11.99 LASER TUBES. Dynamic RAMS EPROMS STOCK * □ ESC. SPEED 1-24 25-99 tOOt STOCK SPEED 1-24 25-99 100 <^ 4125^60 256K X 1 60 ni Z.59 2146 2.2 1 2716 450 nt 3.29 3.13 2-82 4125e-S0 256Kx 1 tOnt 2.19 ZM 1J7 2732 45D ni 4.19 412&6-100 2SBK n 1 100 n« t99 1,70 2T35A 2S0 ni 3.29 3.13 2.82 41256-120 2&6K 11 120 us i.ao 1,62 27G4 25D na 3.49 3.32 2.99 41256-150 25€K X 1 ISA ns 1.79 f.?0 1.53 27£4A 250 nt 3.09 2.94 2.65 5HO0O-70 1 m#g K % 70 ni 5.49 5.22 4.70 27128 250 ni 4 79 4.55 4.10 SllOdO^ 1 m*o I t aons 5,29 503 4.53 27Cm 250 ni 479 4.SS 4J0 siia>o-iD 1 meg X 1 100 ns 5.09 4,M 4.36 im& 250 nfl 439 4.3€ 3.92 5142S&70 256X i4 iJ7 s.sa 17C2S6 250 nt 4.29 4.oa 3,67 514256-80 25£Ki4 aofu 6.09 5.79 5u21 27S12 250 nt 5.49 5.22 4.70 S14ZS6-10 3Se K x4 100 nt S.£9 5.41 4.17 27CSt2 250 nt 5.49 S22 4,7B &4iooo-ao 4 meg < 1 aofis 26.99 25.64 23,09 27C1(S24 200 10.99 10.44 9.40 S4425e^ 1 nwg 1 4 «Ons J 1.99 30 J9 27 JS 21.99 20.ft9 Ti.&O STOCK * WAVELENGTH OlfTPUT OUTPUT BEAM BEAM POLARI- OPERATING OPER. HRING MIN. SIZE WT. ORH PRCE POWER POWER DiAM. OIVERG. ZATION VOLTAGE CURR. VOLT. SERIES t.9 (MIN.} {MAX.1 RES. (IN MM) LTTTTD 543nm (Green} OSraW 1 OmVV 07tmm ^12 mrad randorn t750vl110w 6 5 mA £ 3iiV aih fl 37 Jt3&0 200 M m9§ LT7650 632 Snm iRctI) OSmW 20mW 049mm < 1 ? mrad >100:1 35 mA < 7 kV 6dK n 25 Jt 146 70 m 529.99 479.99 LT?6&6 632 Snm (RtJd) O.SrnW 20/nW 034mm < 24 mrad random lO&Ovi tOOv aflrnA s a kv 82k a 22 Sx lie 60 Ilia 134.99 124.OT 632 Bnm (Red) 0.5 mW 2.0mW 0.49fnFn £ 17 nunU rnndom 3 5 mA S 7 kV 25 K 160 70 lllil 144.90 134.99 LT7e£5S 632.Qnm (Rod) I.OmW 2,0^nW 0,49mm S 1.7 mrnd random lOOOvl TOOv 3 5 mA < 7kV Gak a 25 K 150 70 IMa 159.99 144.99 LT7&32 632.8nm (Red) i.2mW 3 0mW OOlrnm S 3 0 mmri random 13Q0v - tOOv 3 5niA < 7 kV aik fl 20)t210 70 Ilia 249.99 229.99 LT7621S 632 Sum (Red) 20mW 5 OmW 0 75mm £ t 2 mrad random T30(N^ TOOv 5 0 mA ■£ 7 kV eak n 30 V 255 140 1114 204.99 191.99 LT7634 632 enm (Red) 2.0mW 5 OmW 0 75mrn < t 2 mrad >50Q:1 t300v 1 tOOv SOmA < 7kV m n 30x2&5 140 ll4a 209.99 194.99 LT7621MM 633 &rtm (Redi S.OmW v5mW 1 Ofnm 5 2 5 miad random 1250V - lOOv 6 5 mA £ 7kV 30x255 140 urn 359.99 334.99 LT7627 632.6nm (Red) S.OmW l5mW OaOmm ^ t T mrad fandom T900V-100V 65 mA £ SkV aiii fl 37)t350 200 mb 369.99 344.99 LT762e 632. Bnm iRed) S.OmW l5mW 080mm S 1 t mrad >50a:l I900v^ lOOy 65 mA < 8kV aik n 37 IE 350 200 tllb 389.99 364.99 LT7637MM 632 Bnm {Rfti) TOmW 1 Jm-T^ S -l C mr Jd random T750v - 65 mA s a kv 37 n 350 200 1Mb 479.99 444.99 Laser Pointer • Output 3 S mW - Wavetengm 670NM ■ Power Supply: 2xAAA Batteries (included) • Beam ApproK. 3' @ 100 yards Ouantily Discounts At^aFlablc STOCK n PRICE LSPOINT $199,99 Power Supply * Input: 115/230V * Output *5v@3J5A + I2v@ t.SA -I2v@ 4A STOCK # PS1003 PRICE SI 9.99 Coilimator Pen - Output: 2.5 mW (mat J • Current 90-150 mA . Op Voll.. 2.2'2.5V - Wavelength 620NM • Data Sheet mc. STOCK n SB1052 PRICE S39.99 Disc Drive & Computer Cleaning Kit Not a cr . e ci .ifn'i -tikl h compscle compjief cleaning kit Inclydes swabs^, head cleaning iiuiO. ftnti siatic cSc^rter. STOCK # PRICE SB 1099 Kit $6.99 SB1100 5V4"Kit $6,99 Disc Drive Head- Cleaning Kit Anti-Static Screen Wipes Robotic Arm Kit tnctudes cleaning fluid and head leaning diskette STOCK # PRICE SB1105 3Vj ' Drive Kit SL99 SB 11 06 5V<" Drive Kit SI. 99 STOCK # PRICE SB1104 Dispefiser pack SI. 99 of 25 wipes S B 1 1 07 Dispe nse r pack $4.99 ol 100 wipes Avoider Robot Kit An fftEelbgenl fcbot ttisl knows hew Iq mid hinmg «r«lt». Th*$ roboe emits an cnl»-fad tam wtucti deificu an obiSicil in front ano inoo aLitomaetiqany itfms leH and continues cwi STOCK # Y01 PRICE S49,99 STOCK # MV912 PRICE S49.99 ism ORDER LINE — (800) 824-3432 iNTERNATIONAL ORDERS — (818) 341-8833 FAX ORDERS — (818) 998-7975 TECHNICAL SUPPORT — (818) 341-8833 CrnCLE 196 ON FREE iMFORUATlON CARD • 15.D0 MINIMUM ORDER ■ UPS BLUE. a FEDERAL EXPRESS SHIPPING AVAILABLE • OPEN MON-Ffll 9.00 AM - 6:00 PM, SAT 10,00 AM * 3:00 PM PDT • CA RESIDENTS ADD 7%^ SALES TAX • CALL FOR QUANTITY DISCOUNTS • CALL FOR FREE CATALOG (FOR 1ST CLASS 0 ELI VERY OR CATALOOS □ ELtVERED OUTS 10 E THE U.S. - SEND S2.00) • WE CARRY A COMPtFTE UNE OF ELECTRONIC COMPONENTS ■NO SHIPP1I*G CHARGES ON PRE-PAID ORDERS DELIVERED IN THE CONTINENTAL U.S^ i I a 3 S 95 ADVERTISING INDEX RADIO-ELECTRONICS does not assume any responsibility for errors that may appear in the indeK below. COMPUTER COINNECTIOINS continued from page 92 or even 386 op codes), lo perform multitasking, and all sorts of other things creative designers will enjoy thinking up. Product Watch If you've bitten the Windows bug* you've probably heard about Nor- ton's Desktop for Windows CNDW). an everything-including-the-kilchen- sink collection of Wtn3 utilities. If that sort of overblown approach turns you off. check out SideBar (Fig. 2X This is quite simply the most elegant Win- dows program I've seen in four or five years of Windows watching. As the name suggests. SideBar places a bar along the side of your screen: this bar gives you the best of both DOS and Windows. At the lop, the bar contains several pushbuttons for arranging icons on your desktop. Beneath the buttons is a text box for entering DOS commands Cdir, cd. md. etc.). SideBar interprets your commands itself: it does not run a copy of COM- MAND.COM. The remainder of the space is occupied by a set of drive Icons, file/directory listings, or both. The dual display can locate two file windows horizontally or vertically. You can select one or more files fn^m one window and drag them to the other The same approach works for copying, moving, deleting, renaming* changing attributes, assoctating (documents to applications), and placing icons on SideBar to execute directly SideBar can replace Windows' Phd- gram Manager, File Manager, or both. It provides a text-menu approach to launching applications, that while not as visual as NDW is really elegant and easy to use. gj SideBar is extremely resource S aware and efficient. You can force it ^ to unload itself and thereby save g memory when running applications: ^ just double-click on the backgmund 8' to bring SideBar back. The documen- I tation IS quite well done; all pnaduct g packaging is made from recycled ma- ill terials. -§ 1 really like some of NDW's utilities. K. But for the time being, I'm going to use SideBar as my main Windows 96 interface, R*E Free Information Numt>er Page m AMC Sales 77 75 Ace EVoducts . 33, 107 .VII Klecironioi W 176 American Reliance Ijk^ , 23 S4 Appliance Scnice. , . ^ _ ^ ♦ 23 77,182 B&KPrectsiott 17 109 C&SSaks ....,7 — CIE ..,.8,31 186 Cable Warttimi^ . . , 37 Conijnand Pruductions 7 1 1 27 Dece I ndustries , 23 177 EasvTecfi-, ...,.,,93 178 Electronic Goldmine 92 — Electronic Tech. Today ... 16. 82. K3 — Electronics Book flub 79 ] 2 [ Fluke ;Manufacluriii|> CV2 — Cranlhain College , , 15 m Hcathkil - !3 ^ Hlf:liT«xt Ptiblk-ations, fnc 94 — ISCET 28 194 ISECO, Inc. . . 23 114 Jamcco m,9i 104 Jan Cosl^Is .77 ns Jensen Tools ...23 197 M&C; Electronics U MI> Electronics. 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OA 91401 1*eT8-986 200t Rix ^81 6-966-2009 RE Shopper Joe Shere* National Representative PO Bci 169 Idyl I wild, CA 92549 1 ■714-659-9743 Fai V714-659-2469 Science PROBEI — the only magazine devoted entirely lo Amateur Scientists! If you are fascinated by sci- ence in all its many forms . . , if you can't stay away from a microscope, tele- scope, calipers, or test tube — we in- vite you to share the wonders in every issue of Science PROBE! You will join a community of Amateur and Student Scientists who enthusiastically seek scientific knowledge or follow scientific pursuits for their own sakes and not merely as a profession. Obtain your next issue of Science PROBE! by visiting a quality News- stand, Convenience Store, or Super- market or by reserving your personal copy through the mail by completing the coupon below. 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