BUILD AN ELECTRONIC FUSE Ijk 48783 Ki'J ECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE UILD THIS ENERGY- ONSUMPTION MONITOR [eep track of what your ppliances cost to run! CONSUMED ENERGY (CENTS) 1.0 - 1.5 KW 500 - 1.0 KW t80 - 500 W 27 - 1B0 W ENERGY CONSUMPTION MONITOR + TEH RESET □LTMETE 100W / VOLT VIDEO CAPTURE OIM A BUDGET BUILD A THD ANALYZER Use your DMM to display total harmonic distortion! r BUILD THE BATTERY TOOL Get the most out of your nickel-cadmium batteries Use your PC's printer port to import video images! ELECTROMAGNETIC THEORY How electric and magnetic fields interact 71896 48783' 1 1 2 $2.95 U.S. S3.75 CAN GERNSBACK zxxxzm CAR-RT SORT K* CRE33 7504S6HRR5165HB93 12 SD RE X FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST St MEASUREMENT PHILIPS Introducing SCOPEMETEK. There's More Than One Reason to Reach for It. In fact, there's every reason to reach for ScopeMeter."' Because only ScopeMeter combines the expertise of Fluke and Philips to bring you a dual-channel digital scope along with everything you've come to expect from Fluke digital multimeters. The result: an integrated scope-and-multi meter that lets you see a waveform and digital meter display at the same time from the same input. Or switch 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 sales office or your nearest Fluke 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 volts rms. • Rugged construction with shock-resistant holster * Three-year warranty from Fluke. Double Duty. ■ 50 MHz digital storage scope and 3000-count digital multimeter in one heldheld package. ■ Precision Min Max Record and 40 ns Glitch Capture make it easy to troubleshoot intermittent failures. • Simultaneous waveform and digital display on a backlit screen you can read across the room. • Intuitive front panel layout for simple, straightforward operation. ■ Pop- up menus and five function keys for easy control. ■ Autoset automatically sets voltage, time and trigger functions. ■ Safety-designed BPJC connectors and probes simplify floating measurements. FLUKE 9C SERIES SCOPEMETER SELECTION GUIDE FLUKE 97 FLUKE 95 FLUKE 93 Suggested List Price Si m S1495 $1185 Bandwidth 50 MHz Dual Channel Sample Rate 25 Megasampfesysecond Autos el Automatically sets, Voltage, Time and Trigger Multimeter Display V - ;.:. :■;;:■> .-ZZZi Courtis'] True RMS Wis AC or AC+DC Up to 500V (1700V Pk-Pk) Diode Tes: Ltc to 2 BV Continuity Secper Yes Time/Division 10 rts/dw to 60 sec/div VohVDEvisirjn 1 mV/divlolOOWdav SmV/divtolMWdiv Digital Delay or Pre- Trigger By Number ol Cycles, Events. Time. or Zoom Mode By Time Special Mullimeier Modes Min Max Average Record. Relative (zero), d&m, dBV, dBW, Audio Walls. % Scale, Frequency, Smoothing; 1 ' Change Alerr M Frequency, Smoothing"" Change Alefl" Oscilloscope Cursors 12 Measurement, Display 5 Simultaneously Glilcti Capture ■■'■?■ FiC- Wavelurm Processing Average, Variable Persistence, Min Ma* Record Wavelarm Memory SiLire ar& Recall S Waveforms Set-Up Memory Store snd Recall 10 Front Panel Set-Dps Waveform Mathematics Add. Subtract. Multiply. Invert, Filler or integrate Waveloims VK5VL! Sign at Generator Output Sinewaveor Square wave Component Tesler Output Vollage or Current Ramp Gpticatiy Isolated P.S-232-C :?.-r.a Full Operation by Remote Control Primer Output Serial Backlit Display Eiect'oluminfiscenl Goes Wherever You Go. • Runs on rechargeable MiCarJ Batteries. standard C-cells or the included line voltage adapter/battery charger. • Adjustable tilt-stand comes in handy as a hanger, too. • Compatible with a wide range of Fluke multimeter accessories. 01991 John Flu ki Mlg Co.. Inc. Ad No. 00015 FLUKE. CIRCLE 121 ON FREE INFORMATION CARD December 1991 eis* wctroaics Vol. 62 No. 12 31 ENERGY CONSUMPTION MONITOR How much power do your appliances use? Paul Brule 37 VIDEO CAPTURE ON THE CHEAP! Build the Frugal vis ion image-capture board for less than $100. Gene Toner 47 THD ANALYZER Our inexpensive Total Harmonic Distortion analyzer tells you how good your amplifier really is. John F. Keidel 53 BUILD THE BATTERY TOOL Get the most from your rechargeable batteries with this microcontroller-based discharger. Fred Eady 63 ELECTRONIC FUSE Use this handy device when troubleshooting your next project T.L. Petruzellis 60 AN INTUITIVE LOOK AT ELECTROMAGNETIC THEORY The final installment in the series examines the relationship between changing magnetic and electric fields. William P. Rice ■ DHj^i^y.'MTtiT 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 22 EQUIPMENT REPORTS Fluke Model 12 handheld digital multimeter. 69 HARDWARE HACKER FM stereo chips, and more. Don Lancaster 75 DRAWING BOARD Automotive charging systems. Robert Grossblatt 78 AUDIO UPDATE Efficiency and speaker design. Larry Klein 84 COMPUTER CONNECTIONS The latest news from the computer industry. Jeff Holtzman / PAGE 47 BUILD THE BATTERY VSf TOOL ^ 1 £~= g SSgwc •wm sssr if=§S -H— ^TSITm PAGE 53 1 1 ■' ( i j : ^■j 96 Advertising and Sales Offices 96 Advertising Index 12 Ask RE 14 Letters 86 Market Center o 29 New Lit m CD m 24 New Products 4 What's News ID CO to o z o p o UJ 6 Q < As the holidays approach, the last thing anyone wants to do is spend money unnecessarily. This month, we have two projects that just might help save money. You might be spending more than you should on your electric bills, due to power-guz- zling appliances. Find out just how much it costs to run your household appliances with the Energy Con- sumption Monitor featured on page 31, To further pay its keep, the monitor doubles as a power meter when connected to a DMM. Then there's the Frugalvision — the poor man's video-capture board. It costs less than $100 to build this image- capture board for your PC, signifi- cant savings over similar commer- cial products. Turn to page 37 for details. T 2S rrp THE JANUARY ISSUE GOES ON SALE DECEMBER 3 SWEEP FUNCTION GENERATOR AND FREQUENCY COUNTER It measures square, triangle, and sine waves up to 20 volts p-p, has a top range of 2,5 MHz and a ©-digit display/frequency counter H — and it costs just $300 to build. BUILD A MONITOR EXERCISER Troubleshoot computer monitors with this convenient tool. BUILD THE CALL-MATE Convert any phone to a speaker phone. DIGITAL-TO-ANALOG CONVERSION Experimenting with the IBM PC. DRIVER COOKBOOK A variety of practical 7-segment driver techniques. As a service to readers, RADIO-ELECTRON 1CS publishes available plans or information relating to newsworthy products, techniques and scientific and technological developments. Because of possible variances in the quality and condition of materials and workmanship used by feeders, RADIO-ELECTRONICS disclaims any responsibility for the safe and proper functioning of reader-built projects based upon or from plans or information published in this magazine. Since some of the equipment and circuitry described in RADIO-ELECTRONICS may relate to or be covered by US patents, RADEO-ELECTRONiGS disclaims any liability for the infringement of such patents by the making, using, or selling of any such equipment or circuitry, and suggests that anyone interested in such projects consult a patent attorney. RADIO ELECTRONICS. (ISSN 0033-7862) December 1991. Published monthly by Gemsback Publications. Inc., 500-B Bi- County Boulevard. Famiingdale, NY 11735 Second-Class Postage paid at Farmingdale, NY and additional mailing offices. Second-Class mail registration No, FL1 251 66280. authorized at Toronto, Canada- One-year subscription rate U.S. A and possessions $17.97, Canada $25,65 (includes G.ST. Canadian Goods and Services Tax Registration No. Rl 25 1 66280) t all other countries $26. 97. AH subscription orders payable in U.S.A. funds only, via international postal money order or check drawn on a U.S.A, bank. Single copies $2.95. 'K 1991 by Geimsback Publications, Inc. All rights reserved. Printed in U.S.A. POSTMASTER; Please send address changes to RADIO- ELECTRONICS, Subscription Dept., Box 55115. Boulder. CO 80321-5115. A stamped self-addressed envelope must accompany all submitted manuscripts and/or artwork or photographs if their return is desired should they be rejected. We disclaim any responsibility for the loss or damage of manuscripts and/or artwork or photographs while in our possession or otherwise. KriEcnonins Hugo Garnsback C1 884-1 967} found er Larry Stockier, EHF, CET. editor- in -chief and publisher EDITORIAL DEPARTMENT Brian C. Fonton, editor Marc Spiwak. associate editor Kim Ounleavy, assistant technical editor Teri Scaduto, assistant editor Jeffrey K. Hoftzman computer editor Robert Grossbiatt, circuits editor Larry Klein, audio editor David Lachenbruch contributing editor Don Lancaster contributing editor Kathy Terenzi, editorial assistant ART DEPARTMENT Andre Duzant, art director Injae Lee, illustrator Russell C- Truefson, illustrator PRODUCTION DEPARTMENT Ruby M. Yea, production director Janice Box, editorial production Karen S. Brown advertising production Marcel la Amoroso production assistant CIRCULATION DEPARTMENT Jacqueline P. Cheeseboro circulation director Wendy Alanko circulation analyst Theresa Lombardo circulation assistant Michele Torrillo, reprint bookstore Typography by Mates Graphics Cover photo by Diversified Photo Services Radio-Electronics is indexed in Applied Science & Technology Index and Readers Guide to Periodical Liter- ature, Microfilm & Microfiche editions are available. Contact circulation depart- ment for details. Advertising Sales Offices listed on page 96. Radio -Electronics Executive and Administrative Offices 1 516293 3000. Subscriber Cus tomer Service : 1-800-288-0652. Order Entry for New Subscribers: 1-80O-999-7139. ^ The Audit Bureau Bl Circulation IAXIMIZED SENSITIVI We've Carefully balanced the amount of gain used in our input amplifiers - too much or too little results in poor performance. OPTOELECTRONICS' HANDI-COUNTERS™ with maximized sensitivity give you the maximum range for antenna pick-up. Made in the USA MODEL 3000 Multi-function Counter 1 0Hz-3GHz, 1 Digit LCD with frequency, period, ratio, interval & signal level bargraph....$375. Maximum Security Device. Increase your frequency finding™ by 10 times the distance or more. Tunable Preselector APS-104 $995. Counter Sold separately MODEL 8030 With all the features of the 3000 plus enhanced input signal conditioning and enhanced TCXO time base $579. $ 199 The Original Pocket-Sized LED Handi-Counter™ All of OPTOELECTRONICS' LED Handi-Counters™ will: • Count frequencies above 2.4GHz. Have display saving Power Switch {avoids premature LED burn-out, leading cause of counter failure.) Accept no substitutes - Look for the OPTOELECTRONICS name on the label! Model 2300 - 1 MHz-2.4GHz I Available with NiCads and AC Charger Adapter. Complete Package only. ...$128. r Model 221 0A 10Hz-2.4GHz Full range counter. Price includes Nicads & AC charger/adapter. Only OPTOELECTRONICS offers you MAXIMIZED SENSITIVITY. Factory Direct Order Line I "OUU"Ofc / "O"! £. FL(305)771-2050 • FAX(305)771 -2052 5821 NE 14th Ave. • Ft. Lauderdale, FL33334 * 5% Ship/Handling (Max. $10) U.S. & Canada. 15% outside continental U.S.A. Visa and Master Card accepted. CIRCLE 1B9 ON FHEE INFORMATION CARD WHAT'S NEWS A review of the latest happenings in electronics. Visible red laser diode A visible red semiconductor laser diode developed by researchers at Sanyo Electric Company, Ltd. (Tokyo, Japan) has a shorter wavelength — 635 nanometers — and higher power — a maximum output of 33 mW — than any previous red laser di- ode. Because red lasers are visible to the naked eye and are capable of focusing on an extremely tiny area, they can be applied to a wide range of information-processing equipment. The reduction in frequency oscillation length along with the increase in power will allow the semiconductor laser to replace helium-neon lasers in such areas as long-playing optical discs, laser printers, and high-speed, high-accuracy scanner systems used in retail stores The use ot computer-simulation techniques, combined with a number of technological innovations, made the breakthroughs possible. An ex- clusive Sanyo structure, as well as tilting the semiconductor substrate during crystal growth and other crys- tal-growth-enhancement techniques were key to the process, reducing the output "kink" at higher power set- tings, which was a problem with pre- vious applications of the technology. The newly developed semiconductor laser diode has been designed to op- erate continuously at temperatures up to 45°C. A VISIBLE RED SEMICONDUCTOR laser diode developed by Sanyo has the short- est wavelength and highest power output of any such device, which might allow it to be used instead of the currently used he- lium-neon lasers in high-density optical discs and measuring instruments. VCR-quality TV over phone lines Using a new, experimental Bellcore (Livingston, NJ) technology, VCR- quality television, voice, and data can be sent simultaneously over a single copper telephone line. Asymmetrical digital subscriber line (ADSL) tech- nology, using digital signal process- ing (DSP) techniques and experimen- tal very-large-scale integrated (VLSI) circuitry, can expand the transmis- sion capacity of today's copper- based telephone network. DSP rais- es weak transmissions to acceptable levels and VLSI circuitry allows that processing to be done using a few specialized high-speed microchips in- stead of requiring large, expensive computers. ADSL technology is proposed pri- marily for the "customer loop" that links residences and businesses to the central switching office. Even though future telecommunications systems are generally expected to be based upon fiber-optics technology, a large percentage of the customer loops are still copper-based. Accord- ing to Bellcore, ADSL can serve as "an interim technology that can link fiber and copper telecommunications facilities" and provide customers with a sneak preview of "information age" services — including access to library data bases, shop-at-home services, and long-distance "video learning." While ADSL is not intended to take the place of future fiber-optic net- works, on the short term it can pro- vide enough capacity for customers to be able to receive VCR-quality vid- eo along with a regular phone call. Bellcore has already developed an al- gorithm for the real-time compres- sion of video signals within the capacity of an ADSL line. Customers could also use ADSL to transmit low- speed data from their PC's and fax machines or to access data banks. Those services could be provided without the expensive conditioning of lines or installation of circuit re- peaters now needed to get similar services over the already-existing copper lines. Improved current-carrying ability of superconducting crystals In a collaboration between scien- tists at IBM Thomas J. Watson Research Center (Yorktown Heights, NY). Oak Ridge National Laborato- ries (Oak Ridge. TN), Argonne Na- tional Laboratory (Argonne, ID, and the Iowa State University in Ames, IA, the current-carrying ability of single crystals of the high-temperature su- perconducting material known as yt- trium-barium-copper oxide has been significantly improved. The advance might one day be used by scientists to make powerful, compact super- conducting motors, generators, and magnets from the materials. The technique consists of the de- liberate, controlled introduction of de- fects into crystals of the supercon- ducting material by bombarding them with a beam of very energetic, elec- trically-charged atoms of tin. The de- fects cause an increase in the maximum current that a supercon- ductor can sustain, particularly in ex- ternal magnetic fields, by "pin- ning" — preventing the motion of magnetic-field lines that would other- wise produce electrical resistance. The researchers discovered -that the presence of those defects resulted in values of the critical current density (a measure of the maximum current that the superconductor can sustain) that are the highest ever observed for yttrium-barium-copper oxide bulk material at high-temperatures and high magnetic fields. At liquid-nitro- gen temperature (77 K or minus 320°F) the critical current density was 450,000 amps per square cen- timeter in a magnetic field of 1 Tesla. As the heavy-ion bombardment was increased, the critical current density continued to increase as well. The most practical projected use of the bulk material would be in super- conducting wire that would use the material in the form of polycrystals, although further work is needed to make the current carrying capacity of yttrium-barium-copper oxide in poly- crystalline form. B-E AT $299.95, NO OTHER DESIGN WORKSTATION GIVES YOU SO MUCH FOR SO LITTLE. PROTO BOARD BRAND Function Generator ..sine/square triangle ...plusTTL Large Breadboarding area holds 24 ICS ...2,500 tie points Triple Power Supply ...+5V fixed, plus two variable 5-15V 8 TTL Logic Probe Indicators Audio Speaker I Two Digita Pulsers Two BNC Connectors for oscilloscopes and counters Here's PB-503, the total design workstation. It has everything! Instrumentation, including a func- tion generator with continuously variable sine/square/triangle wave forms— plus TTL pulses. Bread- boards with 8 logic probe circuits. And a Triple Power Supply with fixed 5VDC, plus two variable outputs ( + 5 to 15VDC and - 5 to 15VDC). Throw-in 8 TTL compatible LED indicators, switches, pulsers, OVER $600 WORTH OF WORLD CLASS TEST EQUIPMENT FOR UNDER $300! potentiometers, audio experimenta- tion speaker... plus a lifetime guar- antee on all breadboarding sockets! You have everything you need right there in front of you! PB-503— one super test station for under $300! Order yours today!! A016 Call toll-free for details 1-800-572-1028 GLOBAL SPECIALTIES CIRCLE 1 97 ON FREE INFORMATION CARD Mnterptex Global Specialties. /nduifrfw 70 Fulton Terrace. New Haven. CT 06512. company Telephone: (203) 624-3103. 8 Interplex Electronics, 1990. All Global Specialties breadboarding products made in USA. ProtoBoard is a registered trademark of Global Speciailies. D m o CD m I VIDEO NEWS What's new in the fast-changing video industry. DAVID LACHENBRUCH • Widescreen fever spreads. If there was a major theme at the bien- nial International Audio-Video Fair in Berlin, it was widescreen TV with a 16:9 aspect ratio, as opposed to the conventional, squarish, 4:3 ratio. As satellites beamed down 16:9 pro- grams in Europe's D2-MAC ex- tended-definition system and in the compatible HD-MAC high-definition format, a half-million fairgoers were deluged with widescreen pictures of all kinds. The only thing that all of those TV sets had in common was that the screens had a 16:9 aspect ratio. Some were in high-definition HD-MAC, some (via tape) in Japan's Hi-Vision format, some in widescreen MAC, and others in standard NTSC or PAL with the top and bottom of the picture sheared off to obtain the cor- rect aspect ratio. The object lesson learned at the Berlin show is that the average per- son can't tell the difference between all the different formats. At normal viewing distance, it was extremely dif- ficult to tell the difference, raising questions as to whether widescreen had more appeal than HDTV. While the original widescreen sets introduced in Europe by Thomson Consumer Electronics under the Thomson, Nordmende, and Tele- funken brands, were 36 inches in overall diagonal and used direct-view picture tubes (actually 34 inches in viewable diagonal by American mea- surements), the high cost of such sets — $5000 and up — prompted the early introduction of sets with smaller screens. Presumably, Thomson al- ready was feeling the effects of con- sumer resistance. As one show attendee put it, "The choice is be- tween buying a widescreen TV and a used car." Thomson thus introduced new sets with picture tubes measuring 32 and 28 inches in overall diagonal measurement C30 and 26 inches in American "viewable diagonal" terms) at lower prices. At the same time. Philips announced 46-inch proj- ectors in the widescreen ratio at about the same price as Thomson's 36-inch direct-view sets. While some 20 brands showed widescreen sets, not all manufacturers were enthusi- astic. Matsushita (Panasonic). Mit- subishi, and Sony said that their demonstrations were just to prove that they had the technology, but they would not offer sets until they were convinced that there was sufficient widescreen programming available. Nevertheless, all the major European TV makers — including Grundig. Nokia, Blaupunkt, and Metz — joined in quoting prices and delivery dates. • Questions remain. While Euro- pean TV manufacturers were pushing widescreen sets, the entire issue of HDTV remained tied up in politics. Backed by set makers, the European community was trying to adhere to its schedule of converting all direct sat- ellite broadcasts to D2-MAC in antic- ipation of moving later to HD-MAC. But satellite broadcasters, enjoying good viewership in PAL, were reluc- tant to spend the money to add MAC broadcasting — not to mention com- plete conversion to the new system. European authorities were preparing to defray, or cover completely the costs of adding D2-MAC transmis- sions and to require simulcasting in both PAL and MAC systems for a time, with the deadline for broadcast- ing in PAL coming in 1994. But at the time of the Berlin fair, nothing had been settled, and set manufacturers were pushing widescreen and HDTV sets on the basis of speculation. • PALPIus. Until HDTV comes along, most of the European com- munity has agreed on a system for widescreen TV called "PALPIus." It's an enhanced-definition TV system with the added ability to send a wide- screen picture in full definition. Under the PALPIus system, when a PAL TV station is transmitting a widescreen program, it changes the material to a "letterbox" format, which in the stan- dard PAL format would have only 432 lines instead of the normal 576, But the vertical information that is lost is added to the black bands above and below the letterboxed picture. A sep- arate signal, sent during the vertical blanking interval, tells the receiver that a widescreen signal is being sent. A standard PAL picture will be received on an ordinary set (a letter- boxed picture with black bands above and below the transmitted material), but a PALPIus receiver will receive a full-definition, screen-filling, wide- screen 16:9 picture. • Interactive TV. Interactive Net- work, backed by NBC, Cablevision Systems, and others, made its debut this spring in California and plans to go nationwide this year. The network allows viewers to play along with game shows and compete for prizes. The games are carried on the Public Broadcasting System's vertical blanking interval. Homes equipped with a $400 control unit and paying $15 monthly can participate via a wireless handheld terminal, At the end of each interactive show, the stored data from the home unit are transmitted via a Tymnet phone cir- cuit to Interactive Network's central headquarters, and results of the con- test are displayed on the home unit a few minutes later. • Bullish HDTV study. As a counterpoint to the many studies that have shown that the public can't rec- ognize HDTV and doesn't care, a sur- vey made by HBO two years ago has now been released- That survey, covering nearly 600 viewers in Kan- sas City, indicates that HDTV could win 75% of the replacement TV set market for main household TV's, even if the price is 2V-z times that of a conventional set. In contrast to other studies, which show the widescreen ratio of HDTV sets to be more of an attraction than high definition itself, the HBO study found that most view- ers didn't notice the wide aspect ratio or comment on it. It also showed that viewers like the big screen but not the "big box" it must be wrapped in. HBO forecast that HDTV sales will reach 10,000.000 sets as $1 billion by the year 2000. R-E UP TO Electronics LED CENTER I PROJECT PARTS DC VOLTAGE DC VOLTAGE AC VOLTAGE AC VOLTAGE DC CURRENT DC CUHRENT RESISTANCE RESISTANCE CONTINUITY - CONTINUITY - DIODE TEST DIODE TEST BATTEHY TEST TRANSISTOR "ft 3 Vi DigiT LCD LOW BATTERY BATTERY TEST 3 ISDIoilLCD LOW 9ATTERY ACCURACY - <■ 5SRK3 ACCURACY - KELVIN . 5% RUG 100 Basic KELVIN 150 Basics - I 9.-'- 1 $ 29. 95 JU- VfJLl Atjir AC VOLTAGE DC CURRENT AC CURRENT RESISTANCE CAPACITANCE CONTINUITY TAEC Birrjei DIODE TEST TRANSISTOR hFE 3 1/2 Digit LCD LOW BATTERY ACCURACY - - 0&1ROG KELVIN 200 Advanced •39. » FREQUENCY COUNTER TO20MHZ IDEAL FOR TROUBLE SMOOTHS AOOC VOLTAGE RANGES AC/DC CURRENT RANG ES 5 FREQUENCY RANGES 5 CAPACITANCE RANGES LOGIC TEST CONTINUITY resTEHBUZZEB DIODE CHECK TRANSISTOR HFE TEST LED TEST YEfitfY GOOOBAD DISPLAY -3 I.? DIGIT LCD ACCURACY - 0.5* IMPEDANCE • iDMwOT" KELVIN PRO 400 $ 69 _95 For Mooters I 00. 150. 200 umMWMum, FEATURES ■ ONE DIGIT TRUE HEXADECIMAL DISPLAY WITH BUILT IN LOGIC (MEMORY. DECODER. OR1VEHS) FULL ALPHA CHARACTERS TWO INDEPENDENT CLOCKS ■ USER ADJUSTABLE FREQUENCY A DUTY CYCLES ■ SREADBOAflD.SOO PT PHOTO-TYPE AHEA TWO POWER DISTRIBUTION BUSSES IGND.VCCI ■ i DATA BIT SWITCHES ■ MOMENTARY PUSH BUTTON SWITCH (SPDTI ■ 4 LEO DISPLAYS w IC ORIVEHS ■ POWER SUPPLY: WALL PLUG-IN TYPE. U.L. LISTED ■ VOLTAGE REG:+5 VOLTS. SHORT CIH, OVERLOAD PROTECT ■ HOOKUP WIRES ■ COMPACT CARRYING CASE ■ INSTRUCTION MANUAL FOR BEGINNER TO ADVANCED USERS MADE W(TH PRIDE IN THE USA FREE COMPREHENSIVE TEACHER STUDENT LAB MANUAL Trainer Manual (100 Pgsj gives d^'arled infilrucCiGns An excellent Training tool covering topics lor High Sd'SO lELegirviw AAanari], Trade Sctiotf ^Beginner - intormediatej A College. A PERFECT FiT WITHIN ANY DIGITAL CURRICULUM & YOUR CLASSROOM TEXTBOOK THE KELVIN LDT"' Laptop Digital Trainer ONLY $ 99. Stock No. 840460 WALL TRANSFORMERS 1BREADBOARDS WALL TRANSFORMER STOCK MO. TYPE ■ Frrrul* 220069 avDOSOOmA $3.95 ea 220068 1 2V OC 500 hi A ... $4.25 ea MALE JACK STOCK HO TYPE 370048 2.1 mm Male M9ei ! .39io." COMPONENTS M fffiff G aqga 6S0Q9? ■ I'D •■-■ ■ mmt T*=* ... 1[ . i ■ ! Stock No 600021 600029 600039 TYPE toOHCOST 555 TIMEH.... ! , 20 ea 556 dljju, Tiuen ... 5 .40 ea LM566 PLL • .60 ea PUHCTIOH GENERATOR 74 1C OP-AMP . S .30 EA IHTEHHALLY COHPEM3ATED 1458 OP-AMP., S .35 EA DUAL 741COP-AUP ftp 2N2222 s .18ea PN2222 s .08 ea 7805 VOLTAGE PEG .36 EA SILICON CONTROLLED RECTIFIER (Similar loGECl 06C1 ) 4.0 AMP. TOO PIV 600014 s .89 e* s .79 ek.50. 630038 Slock No 6B0093 630097 680098 630100 2 4 6801 00 Contacts ... youpcost 500 J 4. 25 840 • 5. 55 1380 s 11. ra 2390 S 22. 5S 600013 600026 630041 330383 600 023 WIRE JUMPER KIT Prn-cul. Pre-Stnpned 330289 140 Piece Set „.* 4. 75 330290 350 Piece Set ... s 7. 75 best buy NEW Series II FLUKE 70 sen«ii » 63 FLUKE 73 s.rk. s n l 89 FLUKE75s.h«ii s 127 FLUKE77sfri.su *149 FLUKE 79 series h *169 FLUKE 83 *199 FLUKE 85... s 229 FLUKE 87 •„«■ *269 FLUKE 86 alitohotive ...._ 367 FLUKE 88 At™™™ _.„ s 423 FLUKE 45 s 579 NEW! SCOPEMeTER ■ SERIES HANDHELD, 50MHZ. DUAL CHANNEL FLUKE 93 s 1095 FLUKE 95 s 1395 FLUKE 97 FULLY LOAOEC-. s 1 695 SCOPES 20 MHz SCOPE 5 345 Dual Trace 2 Yr Warranty-Parts & Labor Stock No. T4COB5 SCOPE PROBES SO MHz, XI .". X10 SPECIAL 700072 ... s 18. 95 ISO MHz, XI 700073 ... S 39.' 5 BATTERIES Duracell / Eveready 9V Alkaline Battery ! 1.95es s 1 .75 ea.T0+ 9V Battery * SNAPs HOLDER' Snap M5ea * .1 ea/1 CC+ Holder '-.20 ea ! .10ea100* SPECIAL SPECIAL RED LED As Low As Q>" «'1 '1.79*1 1 1.99 «■ J 1.79 ■■ MOVING SIGN DISPLAY tor Fabricating Tour Own Moving Sdgn tMiplmy SOmrrl STOCK HO. IC CLIPS'- SOLDER TYPE SPRING LOADED Sock Ho. COLOR 99010J BLACK 990105 RED COST 25* Oty .65 ea ' .50 i .65 ea *.50l IC TEST LEAD SET S COLOR CODED IS" LEADS WITH MINIATURE HOOK-ON PROO AT BOTH ENDS Slock No. YOUR COST 990103 s 8.95 ea DOUBLE BANANA JACK Soldering "Vs^ IRON wilh STAND. BLUE LONG LIFE TIP Slock No. 990093 M.50 ea Project Speaker 2", 8 Ohm, .1 Wall Stock No 350008 Project BUZZER 3 -3 Volt DC. GO do SlOCk No. 630065 >1 .59 ea s 1.39 ea/10+Qly ^^ HORN ALARM Loud Penelral'nrj Sound Slock No. 640001 >.75ea gv DC s .69 en; 10+Qty DC MOTOR IOr SQLAR.'HOBOTIC^ StochNo. C'..::.:i i ! .50 ea . ._ 1.5lo6VDC 1 .45 ea 1 20+ Qty XENON STROBE stock No. TUBE 200050 *2.95 ea S 2.50 ea ,' 20+ Qty TRIGGER COIL for XenonSlrobe Tube Stock No. 320037 •1.25M s .89 ea / 20+ Qty INFRARED LED IR Pair, LEO intra transmitter and receiver Stock No. 250DE1 s 2.79 ea NEON LAMP NE2. Long Lead* Sloek No. 2W0OJ ».15oa * .1 2 ea/ 100+ Qty PHOTO CELL CADMIUM SELEIilDE Stock No. 260017 ' .99 ea PHOTO CELL SULPHIDE Stock No. 26001 S s .99ea PUSH-BUTTON SWITCH PLISH-ON, PJSH-OFF Slock No 170021 s .55ea s .49 eaMM+Qty Stock No YOUR COST 3* Qty 600056 *2.30 e FEMALE BNC TO DUAL BANANA PLUG Stock NO YOUR COST 3+ Oly 930103 Vm ea s 2.75 1 DUAL BANANA BINDING POST TO MALE BNC PLUG Slock No. YOUR COST 3t QlY 50005B s 5.95 ea *4.95 ea BNC TEST CABLES 3 ft. MALE TO MALE Slock No YOUR COST 990101 ■S.flS ea SUB-MINIATURE MOMENTARY SWITCH Slock No. 990002 ( .35 ea 1 ■ .28 ea/ 100+ Qty MINIATURE TOGGLE SWITCH Stock No. 270031 '.90 ea Type-SPST s .79 ea'SO+Qly ity ^^t KEL VIN ELECTRONICS CIRCLE RESPONSE CARD 01 WRITE tor pur CATALOG full ol WHOLESALE PRICED ITEMS. OVER 10,000 ITEMS IN STOCK ELECTRONIC COMPONENTS 1 TECHNOLOGY ACTIVITIES VISA & MASTERCARD ACCEPTED $20 MINIMUM ORDER MINIMUM FREIGHT $5 H KELVI Electronics 7 Fairchild Awenue, Plainview, NY 11803 CIRCLE 190 ON FREE INFORFv - • T ION CARD Call: 1 (800)645-9212 , 1 (516) 349-7620 FAX:1 (516)349-7830 8 m CD m 33 If You're Serious About a Future in Electronics, Ensure that Future with the Best Educational Training Available. SEND FOR YOUR CIE HOME STUDY COURSE CATALOG AND RECEIVE A FREE 24 PAGE CIE ELECTRONICS SYMBOL HANDBOOK! Includes hundreds of the most frequently used electronic symbols. Published by CIE exclusively for our students and alumni. Yours free when you request a CIE Course Catalog. I _f you want to learn about electron- ics, and earn a good income with that knowledge then CIE is your best educational value. CIE's reputation as the world leader in home study electronics is based solely on the success of our graduates. And we've earned that reputation with an unconditional commitment to provide our students with the very best electronics training. Just ask any of the 1 50,000-plus graduates of the Cleveland Institute of Electronics who are working in high-paying positions with aerospace, computer, medical, automotive and communi- cation firms throughout the world. They'll tell you success didn't come easy. ..but, it did come.. ..thanks to CIE. And today, a career in elec- tronics offers more opportunities and greater rewards than ever before. CIE's COMMITTED TO BEING THE BEST.. ..IN ONE AREA.... ELECTRONICS. CIE 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, CIE is 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 exclusively in electronics. CIE has been training career-minded students like yourself for nearly 60 years and we're the best at our subject ELECTRONICS ... BECAUSE IT'S THE ONLY SUBJECT WE TEACH! CIE PROVIDES YOU WITH A LEARNING METHOD SO GOOD, IT'S PATENTED. CIE's Auto-programmed lessons are a proven learning method for building valuable electronics career skills. Each lesson is designed to take you step-by- step and principle-by-principle. And while all CIE lessons are designed for independent study, CIE's instructors are personally available to assist you with just a toll- free call. The result is practical training... the kind of experi- ence you can put to work in today's marketplace. LEARN BY DOING...WrTH STATEOF- THE-ART FACILITIES AND EQUIPMENT. In 1969. CIE 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. 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Bulletin Benefits rj Veteran Active Duty :%E CLEVELAND INSTITUTE OF ELECTRONICS 1776 East 17th Street Cleveland, Ohio 44114 (216)781-9400 A school or thousands. A cldss of one. Since 1934. ASK R-E Write to Ask R-E, Radio-Electronics, 500-B Bi-County Blvd., Farmingdate, NY 11735 g z o DC | UJ COMPATIBLE CONFUSION I'm thinking of buying an IBM- compatible computer but there are so many models available I'm not sure which is the right one for me. The ads are confusing be- cause I can't find a clear explana- tion of what the difference is between 286, 386, 386SX, and 486 models. I also don't know how to tell which are faster than the others. — J, Behrman, Tampa, FL Some years ago, when IBM was the only supplier in town, it was easy to keep track of what models were available and which ones were faster than others. As soon as the clone makers got into the act (and the "compatible" makers like Compaq and others), things started to get a bit more confusing. Besides making the market a bit more competitive, all the other manufacturers added improve- ments to try and set their machines apart from the others. Let's start at the beginning. The original IBM PC's were based around Intel's 8088, a micro- processor that dealt with data 16 bits at a time. The problem with it was that it had only eight data lines, so 16-bit data had to be taken in two bunches, eight bits at a time. This basic design decision made the printed circuit boards simpler but it also created a real bottleneck when computers built around the 8088 actually had to do 16-bit work. The introduction of the 80286 came with IBM's AT-class machines and they marked a real improvement in speed and power. The 286 was a true 16-bit microprocessor, and the early ones ran at a clock speed of at least 6 MHz, as compared to the 4.77-MHz clock speed of the original 8088 chips. As the market got more competi- tive, Intel licensed several other semi- conductor manufacturers to man- ufacture 8088's and 80286's. It wasn't long before 8088's were avail- able that could run at 10 MHz and 80286's appeared that could run as fast as 20 MHz. These faster chips were used by everyone except IBM for reasons that are as mysterious to me as they are to you. That was also about the time that IBM's share of the market started to drop as welt. The next player to enter the field was the 80386. This was a true 32-bit microprocessor that ran at clock speeds as fast as 20 MHz. It wasn't long before 33-MHz chips hit the mar- ket as well. Since Intel was the sole supplier of 386's, they were a bit pricey, so they came out with the 80386SX— a chip that dealt with 32- bit data internally but only had sixteen external data lines. Similar in opera- tion to the 8088, it took in 32- bit data in two 16-bit pieces, which caused similar speed bottlenecking as be- fore. But it was cheaper. The 80486 is an improved 80386. It deals with data in a much more effi- cient manner and has an integral math coprocessor. There's talk of an 80486SX which, as far as I can tell, is going to be a crippled version of a true 486 since it won't have a math coprocessor built in and may run a bit more slowly. In order to understand which microprocessor runs faster than another we have to put all this in perspective. There are three things that deter- mine how fast a computer can run: The first is the amount of horse- power, or the basic clock speed ; the second is the size of the tires, or how many bits it can deal with at one time; and the third is how well the engine is tuned — or how efficient the instruc- tion set is. A 20-MHz 286 will outper- form a 16-MHz 386SX in terms of speed, but the 386SX has an en- hanced instruction set that will let it do things like multitasking. What you should buy depends on what you want to do. As things stand now, 8088-based computers are di- nosaurs and the only reason to even consider buying one is that they're really cheap. But even that's not com- pletely true because a computer has a lot more stuff in it than just the motherboard, and the overall cost of video, disk drives, and other pe- ripherals is going to be more or less the same regardless of what you have as a microprocessor. If you're like most computer owners, your main use for the ma- chine is for word processing, database stuff, and other things like games, so the best overall choice is a fast 286- based computer. It will out- perform a slower 386SX and will also be less expensive. If you're planning on doing CAD or lots of Windows-type graphics, you should look at a 386, a fast 386SX, or even a 486. You're the only one who can decide what you need but don't be taken in by the argument that a 286-based computer is going to be obsolete tomorrow or any day soon. Remember that word processing and other basic computer uses were around and thriving before the 286 Cor even the 8088, for that matter) ever appeared on the market. CABLE ID I'm in the audio business and most of my work involves install- ing mikes, cables, amplifiers, and speakers for live events. One of the biggest headaches I have is keeping track of which cable goes where. Even though I've worked out a good marking sys- tem over the years, mistakes are made on nearly every job. Do you have a small, handy circuit that will make it easier to identify ca- bles? Some of the runs are over a hundred yards long. — D. An- drews, Sandy Hook, NJ FKEpi/£#CY /OOK JOK — w* — + 9V JuF 8 OHM FIG. 1— TO TRACK CABLES elec- tronically, you can use this circuit. The LM386 is set up as a simple oscillator and the potentiometers adjust the frequency and gain. 12 The problem with color coding wires is that there are only so many colors, it's hard to see them in the dark, and after a while the cables get so dirty you can't see the colors any- way. What you need is some way to track them electronically, I've had the same problem on various occasions and the answer is yes, you can use the same handy dandy circuit t de- signed for myself. The schematic is shown in Fig. 1 and, as you can see, there's no gee- whiz stuff in the circuit at all. The LM386 is set up as a simple os- cillator. Two potentiometers are used to adjust the frequency and the gain. You can build the circuit using any technique from point-to-point wiring to a printed circuit board. The best part about it is that all the parts should cost less than five bucks and you can get every one of them nearly anywhere. Basically the circuit generates a tone Cwith an adjustable frequency and level), that can be fed directly into a cable or, as shown in Fig. 1, into a speaker. If you're troubleshooting a cable with bare wire ends, you can hook the output of the circuit directly to the wire, and an amplifier of some kind at the other end of the cable will reproduce the tone. When dealing with a cable that already has a mike on it, use the speaker as shown in Fig. 1, secured to the mike with a rubber band, and feed the tone in that way. Then, at the other end, you'll be able to identify which cable has the tone on it. I usually use several of these tone-generator circuits, each set to a different and discernable fre- quency so I can trace several cables at once. I've been using this circuit foryears and have never had a bit of trouble with it. The oscillator is self starting and it will work for a long time before you have to change the battery. NO NEED FOR COLOR I recently got some software that I have to use for work but it was designed to work in color and I only have monochrome vid- eo on my computer. I don't really feel like spending money on cotor since this is the only thing I need it for. Is there some way for me to emulate color with my setup? I have a 286 AT with a Hercules- compatible video card. — B. Fish, Anawana, NY There may be a way to do what you want but it all depends on the kind of video the software needs to work. There are several public domain pro- grams around that will let you run some CGA stuff on some Hercules- compatible cards. But the key word here is "some." I know for a fact that you'll find one of these programs, SIMCGA, on the RE-BBS (516-293-2283, 1200/2400. 8N1). There are other programs as well, and a tour of IBM bulletin boards (or services like the Source and CompuServe) will undoubtedly turn up other ones as well. There's no way I can tell you whether they'll work on your system with your software since there are just too many variables. How successful you'll be depends on how close your video BIOS is to the original Hercules BIOS, how the video memory is organized on your card, how your software writes to the screen, and so on. The only thing you can do is to download some of these emulation programs and try them on your computer. Before you get started on this, however, remember that every one of these programs is designed to emu- late CGA stuff and that's all. If your software does EGA or VGA color, you're probably out of luck. I go up on the boards fairly often and don't re- member ever seeing EGA-to-Her- cules emulation software. I'm not even sure it's possible. WHAT IS THD? I've been shopping around for a new stereo amplifier, and I noticed something referred to as TMD. I'm not sure what THD is, and what to look for when com- paring THD ratings. Can you help me out?— R.V. Wendel, New York, NY An "ideal" amplifier would exactly reproduce the input signal, amplfied. at the output. However, you ' II find that "real" amplfiers tend to add a bit of their own harmonics to the output signal, THD, or total harmonic distor- tion, is measured as a percentage of the input signal, and it's the summed levels of all the added harmonics. Al- though you should look for as low a THD rating as possible, the final deci- sion should be made after you hear how the amplifier sounds. For more information on what THD is, and how you can measure it, see our article on page 47. R-E Sl4HJ)60tl/ iHUHM. 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First. DE- BUG needs to be told about the IN file, or nothing happens. When the IN file is ready, enteral the DOS prompt; ODEBUGrii|M ^ M. 59.95 377B $26.95 Count* ■• 2 600 ■ tO*-COST ■ ELECT PDiUC 1 CffCUiTS |€)| B.mc Electronic* Course | .=. 3219 327,95 Counts it 2 2G13P $17.95 All books are hardcover unless number lolEcwed by a "P" for paperback. ELECTRQ^JCSBQariCLJB Blue Ridge Summit, PA 17294-0810 Please acc&pl my membership in the Electronics Book Club and send the 5 volumes listed below, billing me $4.95. If not satisfied, I may return the books within ten days withbut obliga- tion and have my membership cancelled. I agree to purchase at least 3 books at regular Club prices during the next 12 months and may resign any time thereafter. A shipping/handling charge and sales tax will be added to all orders. Name _ Address City State Zip Phono Valid (or new ■minHjei** only. Foreign applicant wilt receive special ordering inAtructlons. Canada must remit in U.S. currency. This oirrjier subject to acceptance by [he Electronics Booh Club. RPIE1291 i i 3475 927.95 Counts as ■ ©1991 ELECTRONICS BOOK CLUB Blue Ridge Summit, PA 17294-08 10 □ m o m S 03 m 3) 15 Learn to troubleshoot and service today's computer systems as you build a 386sx/20 MHz mini tower computer! Train the NRI way — and learn to service today's computers as you build your own 386sx computer system, now with 1 meg RAM, 40 meg IDE hard drive, and exciting new diagnostic hardware and software! Jobs for computer service technicians will almost double in the next 10 years according to Department of Labor statistics, making computer service one of the top growth fields in the nation. Now you can cash in on this exciting opportunity — either as a full-time industry technician or in a money-making computer service business of your own — once you've mastered electronics and computers the NEI way. NRI's practical combination of "reason-why" theory and hands-on building skills starts you with the funda- mentals of electronics, then guides you through more sophisticated circuitry all the way up to the latest ad- vances in computer technology. Train with and keep a powerful 386sx/20 MHz computer system plus popular Microsoft 3 Works software! Only NRI gives you hands-on training with the finest example of state-of-the-art technology: the powerful new West Coast 386sx/20 MHz mini tower computer. As you assemble this 1 meg RAM, 32 -bit CPU computer from the keyboard up, you actually see for yourself how each section of your computer works. You assemble and test your computer's "intelligent" keyboard, install the power supply and 1.2 meg, high- density floppy disk drive, then interface the high-resolu- tion monitor. Your hands-on training continues as you install a powerful new 40 meg IDE hard disk drive — now included in your course to dramatically increase the data storage capacity of your computer while giving you lightning- Quick data access. Plus you now go on to work with today's most popular integrated software package, Microsoft Works, learning to use its word processing, spreadsheet, data- base, and communications utilities for your own personal and professional applications. But that's not all. Only NRI gives you hands-on training with the remarkable RJL.C.E.R. plug- in diagnostic card and QuickTech diagnostic sofhvare from Ultra-X— professional, state-of-the- art diagnostic tools that make computer troubleshooting fast and accu- rate. ^^^^^ s w ^. QuickTech s . * QuickTech | - QuickTech 1 if m* 2L r.f:., m^Sm ■S'S ■.-;.* w M Hi 111** V 1 Your NRI computer training includes all this: • NRI's unique Discovery Lab"- for circuit design and testing * Hand-held digital multimeter with "talk-you-through" instructions on audio cassette • Digital logic probe that lets you visually examine computer circuits * The new West Coast 3S6sx/20 MHz computer system, featuring a high-speed 80386sx CPU, 1 meg RAM, 101-key "intelligent" keyboard, 1.2 meg high-density floppy drive, and high-resolution monitor * 40 meg IDE hard drive • MS-DOS, GW-BASIC, and Microsoft Works software • R.A.CE.R. plug-in diagnostic card and QuickTech menu- driven diagnostic software * Reference manuals with guidelines and schematics printer ports, serial communications ports, video display memory, floppy drives, and hard disk drives. Only NRI gives you such confidence -building, real-worid experience. Only NRI gives you both the knowledge and the professional tools to succeed as today's in-demand computer service technician. No experience needed .,. NRI builds it in NRI training gives you practical, hands-on experience that makes you uniquely prepared to take advan- tage of today's opportunities in computer service. You learn at your own convenience in your own home. No classroom pressures, no night school, no need to quit your present job until you're ready to make your move. NRI starts you with the basics, building on that foundation step by step until you have the knowledge and skills you need for success. And all throughout your training you've got the full support of your personal NRI instructor and the entire NRI technical staff, always ready to answer your questions and help you achieve your training goals. FREE catalog tells more. Send today! Send today for NRI's big, free catalog that describes every aspect of NRI's innovative computer training, as well as hands-on training in other growing high-tech career fields. If the coupon is missing, write to: NRI School of Electronics, McGraw-Hill Continuing Education Center, 4401 Connecticut Avenue, NW, Washington, DC 20008. NOW! Training now includes Ultra-X diagnostic hardware and software for quick, accurate troubleshooting! Now you train with and keep the latest in diagnostic hardware and software: the extraordinary R.A.CE.R. plug-in diagnostic card and QuickTech diagnostic software, both from Ultra-X. Using these state-of-the- art tools, you learn to quickly identify and \x, f\ / \. ^ service virtually any computer problem on XT, AT 80286/80386, and compatible machines. You discover how to use the R.A.C.E.R diagnostic card to identify individual defective RAM chips, locate interfacing problems, and pinpoint defective support chips. Plus you learn to use your QuickTech diagnostic software to test the system RAM and such peripheral adapters as parallel IBM is a registered trademark of International Business Machine* Corp. R.A.C.E.R. and QuickTech arc registered trademarks of UltraOC, Inc. SEND TODAY FOR FREE CATALOG McGraw-Hill Continuing Education Center 4401 Connecticut Avenue, NW lU Schools Washington, DC 20008 ftfli I^Check one FREE catalog only r^ MICROCOMPUTER SERVICING J TV/Video/Audio Servicing ~" 1 Telecommunications □ Industrial Electronics U Security Electronics l~. Electronic Music Technology G Basic Electronics H Automotive Servicing For career courses approved under GI Bill D check for details. D Computer Programming H PC Software Engineering Using C □ Desktop Publishing n Word Processing Home Business □ Paralegal □ Building Construction □ Bookkeeping & Accounting Name (please print) Address City/State/Zip Accredited Member, National Home Study Council 3-1 21 by RMS ratings. That should be ap- parent, since the RMS power value can be synonymous with the product of a steady state voltage and current. Since fuse operation is dependent on the melting of an alloy, selection based on RMS values of current should be apparent. Second, the generic term "fuse" should not be used. Each fuse type has certain characteristics and a typ- ical time-ampere plot associated with it. When speaking of a specific ap- plication, the type of fuse should be specified. Third, a system should be fused for its weakest link. Murphy's Law works well here: The transistor protecting the fuse blew. In a typical stereo sys- tem, that might mean the maximum collector current of the output tran- sistors, the current driving capability of the amplifier, the speaker rating, and common sense. With the proper output transistors and fuse, reason- able short-circuit protection can be provided. The speakers might have either RMS or peak ratings. Select the fuse based on the equivalent RMS value Kepro Gets You Started ! With Complete PCB Kits. Get that electronic construction project started with professional- quality PCB's that you can make af home. Kepro makes it easy to produce your own etched circuit boards with all the quality materials and step-by-step instructions you'll need. Hobbyists really go for our complete kits for: • Dry film photoresist • Photo reversing • Resist etched circuits • Screen printing • Art layout • Nameplates • And more All Kepro products are easy to use and come with an uncondi- tional guarantee. Call us for more information and to get your FREE Booklet on how you can get started making your own PCB's with Kepro products. 1-300-325-3878 1-314-343-1630 (St. Louis) kepro Kepro Circuit Systems, Inc. 630 AXMINISTER DRIVE ■ FENTON, MISSOURI 63026-2992 of current at the nominal impedance of the speaker voice coil. For exam- ple: A 125-watt amplifier driving 8 ohms, with output transistors rated at 30 amps peak collector current, driving speakers recommended for a 15- to 100-watt amplifier at 8 ohms, which includes an internal fused tweeter rated at 35 watts peak, is used in a living room in a single resi- dence home. For the tw eeter fuse amp erage, A = 0.707V35 watts/8 ohms = 1.5 amps. For the overall speaker fuse amperage, A = V100 watts/8 ohms = 3.53 amps. The a mplifier fuse amper age, A = V125 watts/8 ohms = 3.95 amps. Therefore, the amplifier fuse should be less than 3.53 amps and the tweeter fuse should be less than 1,5 amps. Since we are using this amplifier in the home and not at high- volume levels, it makes sense to pick 1 .25A for the tweeter and 3A for the amplifier. If the fuses blow needlessly, then increase the value slightly Now, for the fuse-type selection process. The Buss man AGX series, a %x 1-inch, non-time-delay fuse, is a good bet. You cannot physically sub- stitute fuses with different charac- teristics, such as time-delay for this application RON DOZIER Wilmington, DE The fuse values for the speaker- protection circuit, shown in Table 1 of my article, were calculated using peak voltage values, because peak current flows during these periods. The peak voltage values themselves were determined by calculating the value of the DC rails, which must be present to create a given amount of average power dissipation within a speaker of a given impedance. Be- cause this is true, the values in Table I are adequate to protect an amplifier that Is capable of delivering the rated output power. Keep in mind that the fuse is not for direct speaker protection, but foram- plifier protection — the purpose of the circuit itself is to protect the speakers from a damaged amp. If you do not drive your amp to peak power levels, then choose a fuse that will protect your amp based on a value of 0. 707 times the value from Table 1. 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Southern Ave., Suite 111, Tempe, AZ 85282. 1-800-336-7389. CIRCLE 182 ON FREE INFORMATION CARD CABLE TV CONVERTERS AND DE- SCRAMBLERS SB-3 $79.00 TRI-BI $95.00 MLD-$79.00 M35B $69.00 DRZ-DIC $149.00. Special combos available. We ship COD. Quantity discounts. Call for pricing on other products. Dealers wanted. FREE CATA- LOG. We stand behind our products where others fail. One year warranty. ACE PROD- UCTS. P.O. Box 582, Saco. ME 04072 1 (8O0) 234-0726. CIRCLE 75 ON FREE INFORMATION CARD CREATE INTELLIGENT PROJECTS WITH THE VERSATILE Z8 PROGRAMMABLE MICROCOMPUTER. This powerful comput- er was designed for flexibility and can be used for various electronic projects. I/O Intensive. Up to 20MHz operation. Download programs or run EPROM code. Special hardware fea- tures included. Prices from $125.00. Battery- backed RAM, X-assembler, and other options available. CALL FOR FREE BROCHURE. MJS DESIGNS, INC., 1438 W. Broadway Rd., Suite B185. Tempe, AZ 85282. (602) 966-8618. CIRCLE 199 ON FREE INFORMATION CARD FUNCTION GENERATORS WITH INTEL- LIGENT 100MHz FREQUENCY COUNTER. Sine, square, triangle, ramp, DC & Sync. TTL outputs. Seven frequency ranges: 2Hz to 6MHz (FG-506), 2Hz to 13MHz (FG-513). In- telligent 100MHz frequency counter with period mode. Continuous, trigger, gate, clock, sweep and external frequency modes. Lin/ Log sweep. Adjustable duty cycle/symmetry. Voltage controlled frequency functions. TCXO with 1ppm/yr. aging rate (optional). FG-506 $695.00; FG-513 $1295.00. Call: 800-664-9838. AMERICAN RELIANCE INC., 9952 E. Baldwin PL, El Monte, CA. 91731. CIRCLE 176 ON FREE INFORMATION CARD BOOK II HOW TO GET ANYTHING ON ANYBODY — Lee Laptn has done it again. Cutting edge audio/video surveillance, HIGH PRICED "OFFICIAL" METHODS (and inex- pensive counterparts) that allow investigators to read computers from a distance, bypass passwords, obtain unlisted phone numbers, intercept cellular calls, pagers, and faxes, trace and track with new data bases, sur- veillance proof any room, tap any phone. WHEW! "Really scary stuff — Charles Jaco CNN." $38.50 postpaid ISECO, 2228 El Camino Real, #349-2, San Mateo, CA 94103. Phone 415-513-5549. CIRCLE 183 ON FREE INFORMATION CARD CALL NOW AND RESERVE YOUR SPACE • 6 x rate $940.00 per each insertion. • Fast reader service cycle. • Short lead time for the placement of ads. • We typeset and layout the ad at no additional charge. Call 516-293-3000 to reserve space. Ask for Arline 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 GET YOUR RECHARGE CATALOG FREE...EARN BIG $$ IN YOUR SPARE TIME— All supplies and Do -It -Yourself kits with complete instructions available. Sup- plies cost from $9.95 in qty and you can sell recharged toner cartridges for $40.00 to $55.00 each. Printers include HP LaserJet and Series II, Apple LaserWriter, QMS, etc. Canon PC-25 Copier also. CHENESKO PRODUCTS, 2221 Fifth Ave., Suite #4, Ronkonkoma, NY 11779, 516-467-3205. FAX 516-467-3223, 1-800-221-3516 CIRCLE 137 ON FREE INFORMATION CARD 5 MINUTE ASSEMBLY! 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. 80-130MHZ. 100m W output! VT-75 microtransmitter complete $49.95 + $1.50 S & H. Visa. MC, MO. COD'S add $4.00. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. 1-800-759-5553. CIRCLE 127 ON FREE INFORMATION CARD P m O m m 21 CO o z o a: G Hi i Li. O a < Although there are plenty of high-quality digital multi- meters on the market today, one name stands above the others in sales and customer loyalty: Fluke (John Fluke Mfg. Co., Inc., P.O. Box 9090. Everett, WA 98206). Even though many potential customers as- pire to a Fluke meter, they don't al- ways want to pay the premium price that the meters demand. Fluke, seeing a price-sensitive segment of the market that it hadn't yet tapped, has introduced its new Series 10 fam- ily The Series 10 is designed for elec- tronics repair persons, electrical troubleshooters, and all those hob- byists who are looking for high quality at an affordable price, and not just bells and whistles. We examined the Model 12, the top-of-the-line of the Series 10. At $89.95, it's also the most expensive. (The Model 10 and Model 11 are priced at $69.95 and $79.95.) The Model 12 is a relative small DMM, measuring roughly 1 , /zx2 3 /4x5'/2 inches. At only 10 ounces, it's also reasonable light. The front of the meter is sparsely appointed, with four pushbuttons and one slide switch, and a 4-digit LCD readout. The test-lead input jacks are on the bottom panel of the meter. None of the Series 1 meters offer current-measuring ability. It was a de- cision aimed at keeping the meters' cost down, backed up by market re- search that showed that the vast ma- jority of measurements are voltage and continuity/resistance checks. With those uses in mind, Fluke de- veloped their V-Chek function (avail- able on the Model 11 and Model 12). With the meter in the V-Chek mode — with the power switch slid all the way to the right to the continuity and di- ode-test position — no adjustments are necessary for many measure- ments. If you probe a cable you'll get an indication of continuity or resis- tance. If you probe a power supply — and its output is greater than 4.5 volts — the meter will switch from its resistance/continuity mode to its voltage mode and display either the 77ie lowest priced Fluke meters are worthy to wear the name. CIRCLE 10 ON FREE INFORMATION CARD AC or DC voltage, whichever is great- er. Since the input impedance in the V-Chek mode is a low 2K, it's not suitable for all applications. On the other hand, the low impedance en- sures that leakage won't cause mis- leading readings. M in/max mode Intermittents are never easy to troubleshoot. But the min/max mode of the Model 12 can help. It works not only in voltage mode — where the highest and lowest voltages are re- corded, along with the relative or elapsed time Con a 100-hour clock) of each occurrence — but also in the continuity mode, where it captures intermittent shorts or opens as brief as 250 u.s and displays a symbolic representation of the transition. When powered up, the meter de- faults to its autoranging mode, but any range can be manually selected. The lowest (4000 mV) voltage range must be entered manually. The model 12 also offers a capacitance-mea- surement mode, with five ranges from 1 fxFto 10.000 uJ. The model 12 is a pleasure to use. All controls can be operated conve- niently with the thumb of the hand in which you hold the meter. The simple, 4-button front panel is easy to use — but not the first time you use it. The capacitance switch is easy enough to figure out— it's a large but- ton with the schematic symbol of a capacitor on it. The min/max opera- tion is also easy if you've ever used the similar function before, or if you read the excellent manual that ac- companies the Model 12. The range switch is a button on which is a small square and concentric circle. (For- tunately, the word "range" is also embossed beside it.) While it may be obvious how to turn the manual rang- ing on, it may not be obvious how to return to the autorange mode: You have to hold the button down for two seconds. It's also not obvious that the same button is used to lock out the V-Chek mode, or to disable the continuity beeper. The select button has a similar problem in that it may not be imme- diately apparent that it's used to choose between AC and DC modes, or between continuity and diode-test mode. We should reiterate, however, that once you're familiar with the meter's convention, it's extremely convenient to use. The Model 12 has a DC accuracy of 0.9% + 1 digit, and an AC accuracy of 1,9% + 3 digits. For resistance measurements, its accuracy is spec- ified as 0.9% + 2 digits (400.0-ohm range), and 0.9% + 1 digit (4.000K-4,000-megohm ranges). Its capacitance-measurement accuracy is specified as 1.9% + 2 digits (0.400 p-F— 400 (jlF ranges), and 10% + 90 digits (10,000 u.F range). If you don't need the min/max re- cording mode you may opt for the Model 11. If you also don't need the time-saving V-Chek function, or the ability to measure capacitance, you may want to opt for the lowest-priced Model 1 0. Our money, however, is on the Model 12. It looks like a tough act to beat. R-E 22 I A Shocking Offer! Now for the firsl time in CIE's 56 year history you do not have to be enrolled at CIE to receive our Electronics and Electricity Lesson Modules. Available for a limited time to non-students for the shockingly low introductory price of only $99.50. With CIE's patented AUTO- PROGRAMMED method of learning you" I! quickly learn 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 circuit boards ... and much, much, more. Your commitment to CIE ends with your payment, but CIE's commitment to your success just begins when you receive your lessons, exams, binder and equipment. This special price includes the benefits CIE normally extends to its students and graduates i -v ■ You'll receive CIF Bookstore privileges, a pat- ented learning method, access to CIE's student, faculty and alumni electronic bulletin board and a free issue of CIE's school newspaper "The Electron". 24-Hour grading and unlimited access to CIE's faculty is available on an optional basis. And best of all, when you decide to continue your electro- 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" • Build 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 method • Electronic Bulletin Board privileges All This For <5nTy! $AAso <>> • A $100.00 CIE TUITION CREDIT CERTIFICATE □ Yes, send me CIE's Introductory Electronic and Electricity Lessons and Equipment. Name: Street: Apt, it: City: _ State: Age:- .Zip:. Phone (_ ■ )- I/BHZ3 BOOKSTORE 1776 East 17th Street Cleveland, Ohio 441 14 Total Merchandise: Ohio Residents add 7% Sales Tax: California Residents add 6 1/2% Sales Tax:_ Total this order: S99.50 Shipping and Handling Charges: Method of Payment: Amount Enclosed: D Personal Check or Money Order □ Master Card D Visa $5.00 Card Expiration Date: Signature: CHARGE BY PHONE! 9 AM to 4:30 PM Eastern Time; 1-800-321-2155 ext. 7312; In Ohio 1-800-523-9109 ext. 7312 D m o CD m u to (O 23 NEW PRODUCTS Use the Free Information Card for more details on these products. V) o z o DC P O LU < POWER CONTROL CEN- TERS. Providing surge pro- tection as well as eye-level power control and status checks of your computer system, Proxima's Power- Touch and PowerTouch Plus fit underneath any computer monitor. The control center has a sleek (patent-pending) design that cradles tilt-and-swivel. pedestal-style monitors. Both models exceed indus- try standards for surge, spike, and EMI/RFI noise protection; the Power- Touch Plus has a higher level of surge and EMI/RFI protection; fax and modem line protection; indicators to show low voltage and' building wiring faults; and comes with Proxima's $25,000 Lifetime Equip- ment Protection policy that provides for repair or re- placement of any computer equipment that is damaged due to power disturbances while connected to the PowerTouch Plus. Both CIRCLE 16 ON FREE INFORMATION CARD models help ease the both- er of electrical-cord man- agement, and are compati- ble with any computer that has a desktop monitor, in- cluding Macintosh Classic, floor-standing computers, and portable computers. They are designed to be sandwiched between a computer and its monitor. The PowerTouch and PowerTouch Plus power control centers have list prices of $79.95 and $109.95. respectively. — Proxima Corporation, 6610 Nancy Ridge Drive, San Di- ego, CA 92121; Phone; 619-457-5500. SURFACE-MOUNT TEST LEAD KIT. Standard test leads are too large and clumsy to use on surface- mount devices, Beckman Industrial has come up with the DL249 Deluxe Surface Mount Test Lead Kit. The kit includes small-outline IC (SOIC) clips; surface- mount tweezer probes, crimp-style sprig hooks; a needle-thin, two-inch tip extension: two silicon-insu- lated lead wires; standard probe tips for non-SMD ap- plications; and a carrying case. The tweezer probes have electrically isolated, color-coded tips, each with its own separate input jack to the meter, which makes it easier to make positive connection with the con- tacts at each end of the tiny surface-mount resistors and capacitors. The test leads also have universal plug ends that make them compatible with digital mul- CIRCLE 17 ON FREE INFORMATION CARD timeters from all major manufacturers. The SOIC clips and spring hooks in the kit are designed to al- low easy access to IC's with tight pin spacing. The DL249 surface- mount test lead kit has a suggested list price of $72.— Beckman industrial Corporation, 3883 Ruffin Road. San Diego, CA 9212301898; Phone: 619-495-3218. PORTABLE LOGIC DEBUG- GER. With the versatility of a hand-held test instrument and the power of a 32-bit logic analyzer, the LA-32 debugger from Logix can be used to test and debug a wide variety of digital log- ic and microprocessor sys- tems. The LA-32 features a 32- bit logic comparator with programmable set points, a pulse generator with pro- grammable interval, width, and count capability; a mul- tiplexer that allows the use of any input for a scope trigger; and an autoranging frequency counter that al- lows the selection of any channel or digital compare as its input. The pulse gen- erator can be used to gen- erate a bounce-free pulse or digital level useful for many design and trou- bleshooting tasks. The de- bugger can display 32 digital input channels si- multaneously. Any of those can be viewed individually on an oscilloscope or other digital measuring device by connecting the scope probe to the "trig" output ries include 24-40 pin CIRCLE 18 ON FREE INFORMATION CARD and selecting the desired channel. In EPROM auto- select mode, the L4-32will automatically configure its chip clip pins for several standard EPROM types. The debugger comes with an AC adapter for line use, a 9-volt nickel-cad- mium battery for portable use, and three test clip leads. Optional accesso- 24 PROM clips with cables, and adaptor boards for the XT, Z80, and 8051 . The LA-32 portable logic debugger costs $379; the PROM clips, $50-$60 and the adaptor boards $75 each— LogiX, Inc. 1725 Roselawn Avenue West, St. Paul, MN 55113 Phone: 612-646-2324. TOOL KIT. Tools for the dis- mantling and repair of elec- tronic equipment are in- cluded in Jensen Tool's Mean Little Kit (model JTK-6), The compact col- lection of 24 tools comes in a 7 x 9 x 2-inch padded zip- per case. Included are CIRCLE 19 ON FREE INFORMATION CARD seven sizes of screwdriver, a 4-inch adjustable wrench, two pairs of pliers, a wire stripper, a knife, an align- ment tool, a rule, a hex-key set, scissors, a burnisher, a soldering-iron solder aid, a fork and hook, and more. Two styles of cases are available — vinyl or blue Cordura Plus — and both are designed to hold an op- tional Beckman ProbeMeter. The model JTK-6 Mean Little Tool Kit costs $99 in vinyl or $104 in Cordura Plus— Jensen Tools, Inc., 7815 South 46th Street. Phoenix, AZ 85044; Phone: 602-968-6241. PC DIAGNOSTIC KIT. Intend- ed for use by computer technicians and computer users, the PC Fixer from Sibex contains hardware and software tools for trou- bleshooting and fixing com- puters quickly and eco- nomically. The diagnostic CRAMOUN DeOxidizer IMPROVES CONDUCTIVITY DEOXIDIZES * CLEANS • PRESERVES * LUBRICATES ForAllMetols, Including Gold! CRAMOUN® DeOxidizer imposes conductivity by dfs- sclwg oxides fat form on metal comedos nod con- tact surfaces, dimiroiing unwonted resistance that impedes electrical performonce. CRAMOLIH® is on active ingredient that does riot rely on solvents for perfatmortce. Due to the excel- lent migration properties, CRAMOUN® coats Die entire metal surface and protects it from future oxidation. CRAMOUN® continues to be the most effective ond economical product for improving ond maintaining electrical component reliability. FOR MANUFACTURE, MAINUNAtiCf. AHDSIRVKIOF: • Switches I Relays • Cable Connectors t Adaptors • Edge Connectors ■ Terminal Strips • Plugs t Sockets • Gold Plated Connectors * Potentiometers • Battery Contacts U$[D BY THOU WHO DMAW THIMT: •BellS Howell • Capitol Records' Dolby Laboratories • Hewlett Packard • John Fluke Mfg. • Mcintosh labs • MCI (Sony) • Motorola • NASA • Nokomichi • RCA • Swilchcroft • ond Many More. BOJkJ Exondkk>,CA 921)32-3679 {619)743-7143 IWt(61 9] 74M460 I LABORATORIES. INC. 'Envrronrntntaty Conscious' CIRCLE 50 ON FREE INFORMATION CARD SIGNAL SL-1000 CATV CONVERTER The new SIGNAL SL-1000 comes complete with infrared remote control and features 86 Channel Ifi'i'I'lilUlL'i 111 HIM K l J 1 1 trK»n n 1 1 [t n 1 it > B 'j'J: H I >> I U [ M [ I \ !*!■ (')■ (2, § « ■»-!'; Y ? P 1 HJ (1) Vi-Watt Carbon-Film Resis- tors. 5%. #271-312, Set 100/7.95 (2) Vt-Watt Metal-Film Resis- tors. 1%. #271-309. Set 50/2.99 (3) Color Code Pocket Guide. Resistor, capacitor, inductor val- ues. #271-1210 79" FIG. 6— PARTS PLACEMENT DIAGRAM AND WIRING connections. Use 14 AWG wire for all primary leads, and make sure you wire the hot and neutral leads of the power supply cord to the proper terminations on the AC socket. + rOfc>: r Mk™-J5 '^JfeX T^ ?^w % - 4.1 INCHES -H THIS IS THE FOIL PATTERN of the solder side of the PC board. O i LL) < 0C the ECM, connect a jumper be- tween the + 18-volt supply and TP2. Connect a DC meter to the power-voltage output and check to see that the voltage varies from to approximately 16.5 volts as Rll is varied from one end to the other. As you do that, the LED's should increment at about 0.27, 1.8, 5, and 10 volts. Now, using the formula V C AL=36/rate, where V CAL is the calibration voltage and rate is your cost in cents per kilowatt-hour (check your billing statement or power company for that rate). Adjust Rll to read that value on the volt- meter. That will enable you to cal- ibrate R14 so that you obtain one pulse per second (1 Hz) at TP3. A doubling or halfing of V CAL should approximately double or half the pulse rate. Remember, each pulse represents Viooo of a cent. Disconnect the jumper used in the previous procedure and con- nect a 100-watt light as a load. Using an oscilloscope, monitor the waveform at TP2 and set R7 so that the sampling ends at the very peak of the incoming wave- form, which should look like the waveform of Fig. 3-g. Finally, power calibration is the last to be performed. With the 100-watt light connected adjust Rll so that a DMM, connected to the external voltmeter jacks, dis- plays 1.00 volt DC. You may want to verify that wattage by measur- ing the voltages across shunt re- sistor Rl, and the line. With those two voltage readings, the power maybe calculated using the formula P(watts) = V SHUNT x V L | NE /R SHUNT , where R SH unt * s th e shunt resis- tance (four 0.39-ohm resistors in parallel = 0.0975 ohms). V SHUNT is the voltage drop across Rl and V LINE is the AC line voltage. That completes the assembly and calibration of the ECM. There is one point that should be mentioned here. The voltage to pulse converter will not start un- til there is a load of approximately 30 watts, meaning that the coun- ter will not increment unless the load is heavier than that value. For those of you wondering if investing in an energy consump- tion monitor is worthwhile, con- sider this: You'll be able to determine how much it costs to run a particular appliance for a certain length of time. So it's easy enough to figure out if it's actu- ally cheaper to run the micro- wave oven for five minutes or the conventional oven for ten min- utes, and so on. Using the energy consumption monitor, you'll also be able to determine if buying ex- tra meat at really good sale prices actually saves you money in the long run. The greatest advantage of the energy consumption is keeping one step ahead of your power company. R-E 36 Build the Frugalvision — a low-cost Image capture device for your PC. mums (Si GENE TONER IN OUR AUGUST '90 ISSUE, RADIO- Electronics introduced a low- cost image capture board for the PC. For $199, it was one of the least expensive, highest perfor- mance real-time image capture boards ever offered for the PC. The author later redesigned the board to increase its speed and functionality, and add a phase- locked loop for better pixel align- ment ($269). Further develop- ments led to a scientific-level res- olution, real-time, AT bus-level Supervision 16, a 512 X 480 pix- el version, offered at $369. But not everyone was happy. Many readers wanted an image- capture system for under $100-— the magic number! They didn't mind that some performance was sacrificed. Real-time capture wouldn't be a requirement, just let everyone have the ability to capture useful pictures, cheaply. Okay, no more mister nice guy. Well show you how you can build the Frugalvision — an image-cap- ture board for under $100! No, the board doesn't capture in real time, it takes about eight sec- onds to capture an image, so the subject had better stay real still! (In fact, we recommend that you use the system to copy existing still scenes and photographs.) What it can do is this: • Capture an image with a reso- lution of 256 x 244 pixels with 64 shades of gray. • Lock onto any standard (RS-170) video source with a phase-locked loop Input section. • Perform DC restoration of the input video signal. • Automatically detect input sig- nal strength and adjust the dig- itization reference accordingly (referred to as autowhite level), and pass the pixel value to the PC via the printer port. What you get is a very useful digitized image on the PC. Our standard Supervision software has been updated to support this board, so all of the functionality such as image pro- cessing functions, industry stan- dard file formats, and printing functions is included. How we did it In order to reduce the cost to less than $100 for an assembled unit, some decisions were made early in the design stage. We con- sider a minimum requirement for a workable digital image to be a resolution of 256 x 244, with 64 levels of gray, A resolution of 256 pixels per horizontal line re- quires a digitization rate of about 5 MHz, which is also the required burst data transfer rate if no buff- er memory is available. There are no PC's currently available which support that kind of transfer rate over the standard IO channel without the use of direct memory access (DMA). We also like to use the original 4.77-MHz PC as a baseline for all of our designs so we don't have to make excuses to people with older machines. All of our real-time capture boards have a full picture's worth of buff- er memory mounted onboard for that reason. To avoid the cost of a buffer memory and all its associated cir- cuitry, we decided not to capture □ m o m 03 o z o CE p o _i UJ Q D < FIG. 1— BLOCK DIAGRAM of the Image capture board. in real time. The device also at- taches to the standard printer port to save the cost of I/O bus- decoding hardware. So, you might wonder, how does one digitize a signal which normally requires a 5-MHz trans- fer rate with a much slower rate? We use the following technique. The horizontal line rate is 15,750 Hz for an RS-170 video signal. During each horizontal line, a single data sample is taken, and passed to the PC via the printer port. The single sample is the de- sired pixel. For example, if the 50th pixel on a line is sampled, 50 pixel times are counted from the start of the horizontal sync pulse. A sample is taken by the A/ D converter, the PC is informed that a sample is ready, the PC transfers it into main memory, and the procedure repeats on the next horizontal line until the 50th pixel for all horizontal lines is taken. The next column of pix- els is then captured one by one, until all pixels are captured. The scan of the picture is in the ver- tical direction as opposed to the horizontal direction, which is normal with a real-time digitizer. The rate required to do that is the horizontal scan rate as opposed to the pixel rate, which a 4.77- MHz PC is just capable of doing if carefully programmed in assem- bly language. Figure 1 is a block diagram of the various systems required to digitize an image in this fashion. PC printer port background The PC's printer port is some- what of an oddity, mixing output- only lines, input-only lines, and open-collector lines with pull-ups capable of being read back. This mixed bag of capabilities has re- mained with us from the first PC's up through todays PS2's and EISA machines, allowing the dig- itizer to be connected to any com- patible machine. The PC and its BIOS are capa- ble of dealing with three printer ports residing on the machine at once. The base addresses of the printer ports are 03BC. 0378, and 0278. The first place the BIOS looks for a port is at 03BC, then 0378, and then 0278. The first one it finds becomes LPT1. the second LPT2, and so on. The 03BC port is usually found on display-adapter cards such as a monochrome graphics printer (MGP) card, and the other two addresses on standard IO cards such as a serial/parallel game card where the address would be jumper selectable, along with its associated interrupt. The printer port is mapped into three addresses, the base ad- dress, the base + 1, and the base + 2. The base address is a port with eight output lines. Those lines are output-only, and usually feed character data to a printer. We use these lines to se- lect a pixel within a horizontal video line to capture and specify the column. Data bits through 7 correspond to printer port con- nector pins 2 through 9. The second address, base+1, consists of four output open-col- lector lines with read back ca- pability. What that means is if the outputs are placed in a high con- dition (the open-collector driver is not pulling the output low) the output can be driven by an exter- nal source. Reading those lines reveals the state of the external signal as long as the internal driver is off. The first line is the busy signal, mapped to pin 1 of the interface. It is an inverter used to switch the input data multiplexer and reset the data ready input. That signal maps to bit of base + 1. 38 » R7 10K n£ 02 1N414B Dl "H° 1N4148 J> C4 ' * KS 4 IC3-* Ijtf 100K? VrLM35BN ► 9V R2 510U C1 1(iF Rf 7511 G3 330pF VIDEO SYNC IC1 LM18S1 c V, GND ODD SET R3 680K 81 T J1.ZS + 5V IC4 CAS30I Be OF vz CE2 CE1 CLK PR REF+ BS B4 RC 83 B2 B1 Si REF- f5V C6 330pF J1.Z4 J1.23 J +5V BST J $i R9 on RAO RA1 RA2 RA3 RA4 RA5 RA6 RA7 IC6 iactfs 19 OUT7 IS Q\jT(, 17 00T5 16 OUT4 IS API 14 DREADY 13 ADO ■ fjl-15 > DRFAD eg 0UT4 pin 16 = pos com feedj or OUT5 pin 17 = pos com feed or OUTS pin 18 = pos com feed" or OUT7 pin 19 pos com feed" or "Internal Nodes" AC node 21 "Asynchronous Clear nc SP node 22 "Synchronous Preset nc EQUATIONS VTD = BST i * /BST OUT4 = D2 * DRD ENABLE VID = /BST + DO * /DRD DRDY = /ST ADO := /ADO 4 DRDY * DRD + ado * AD1 OUT7 = /D5 AD1 := /AD1 * ADO + AD1 * /ADO OUTS = D4 + ADO * AD1 0UT5 D3 * DRD 4- Dl * /DRD should not be terminated. Cor- rect that problem. If all is well here, move to pin 2 of IC1, which should be a baseband video sig- AC = /ST nal with the sync tips at 1,5 volts. If that's not the case, check around IC1 for shorts or open (cold solder) joints. 44 FIG, 4 — THE AUTHOR used Vis-watt resistors for a compact finished product. , 1 ^8 ^. R2 R3 ; FIG. 5— FOLLOW THIS PARTS- PLACEMENT diagram when assembling the Frugalvision. If all is correct, check pin 1 for a strong (0 to 5-volt) composite- sync signal. Check pin 3 for a ver- tical-sync signal, pin 5 for a good color-burst signal (looks like the composite sync signal) and pin 7 for the odd/even signal. The odd/ even signal is the real indicator of circuit health, and is the first one to become erratic. It should be a to 5-volt square wave with a re- peatable half cycle time of 16.6 ms, the period of one RS-170 field. If one or all of these signals are not present, check the whole area. The 680K-ohm resistor R3 is most important in producing the odd/even signal. Itshould not be replaced by any other value, and because of its high imped- ance, all flux should be removed from the board. If everything is okay up to this point, pin 4 of IC2 should be pro- ducing a waveform with a fre- quency close to 5 MHz. Another check on the phase-locked loop is to monitor pin 9. This should be a signal whose normal level is be- tween 2 and 3 volts, with a spike at every vertical sync (16.6 ms in- terval) decaying rapidly back to the steady DC level. If that does not occur, check around the PLL and its associated parts for opens or shorts. The remainder of the circuits interact with the soft- ware, and are very difficult to trouble shoot. Being digital in nature, they are very reliable. Since the board does not have nor require any adjustments, boards which fail to generate a picture Eire normally due to errors in construction, parts place- ment, orientation, and improper soldering. If VGRAB finds the card cor- rectly (no commercial), the main menu will appear on the screen. Simply press enter to capture and image. This process takes about eight seconds, and then the screen is blank during this period with the exception of the "Press esc to return" message on the right side of the screen. When the picture is displayed, return to the main menu to save the image or for additional image process- ing functions. Since Frugalvision does not pass the printer-port lines through, the printer must be dis- connected when capturing im- ages, and reconnected when printing. A solution to this is a separate printer port for Fru- galvision. Frugalvision processes data at very high speed, and therefore should not be con- nected to any significant length of cable (more than about 3 inches), so connection to a printer-port switch box is out. The author has tried it and doesn't like the picture. Since capturing images is not done all the time, flipping cables is nor- mally acceptable. In that case, re- member that when Frugalvision is connected, a printer is not so don't try to use the printing func- tions of Supervision software un- til a printer is connected back up. Software comments A very capable software pack- age the author used for sche- o m m 3 (D CD 45 Jf Ti- ,*-** -* m mm* . " — •*■■■ COMPONENT SIDE for the PC board. matic capture and board auto- routing is the Draftsman-EE, a PC-based CAE tool from Design Computation, Inc. Design Com- putation also offers excellent cus- tomer support. Frugalvision's images work with many different software packages, but older paint pro- grams, which state they are TIFF and PCX compatible, are com- patible with older versions of those standards. Specifically, they are compatible with TIFF B (black and white, no grays) and 16 -color PCX. The authors pro- gram produces TIFF G (gray scale) and 256-color PCX which Is a requirement to store the 64 and 256 gray-scale images. New- er programs such as PC Paintbrush 4 work well with the files but usually require a VGA screen to do so. High-end publishers such as Ventura and Pagemaker accept Frugalvision files with no trou- ble, and do an excellent job of printing images. For the image experimenter, there is a very effective C-lan- guage library of image process- ing and hardware support func- tions from Catenary Systems called the VICTOR image pro- cessing library. It contains full standard memory, EMS and ex- tended memory support, laser printer support, and low-level hardware support for Frugalvi- sion cards. In fact, nearly all the functions in VGRAB are done by using the support in that pack- age. Anyone doing serious pro- gramming in the image-process- ing field should look into the VICTOR package. SOLDER SIDE for the PC board. Catenary also produces COLOR KIT, another software product that works with Fru- galvision boards. This product provides three colored plastic fil- ters (red, green, and blue) to place in front of the camera lens at capture time. Three files are saved and the color-kit software assembles these files into a full- color image. The pictures that are produced on a 256-color VGA screen have to be seen to be be- lieved, R-E y z o DC ID o Q < cc 46 Be an FCC LICENSED ELECTRONIC TECHNICIAN! No cosUy school. No commuting to class. The Original Home-Study course prepares you for the "FCC Commercial Radio- telephone License." This valuable license is your professional "ticket" to Uiousands of exciting jobs in Communications. Radio- TV, Microwave, Maritime, Radar, Avionics and more., .even start your own business! You don't need a college degree to qualify, but you do need an FCC License, No Need to Quit Your Job or Go To School This proven course is easy, fast and low cost! GUARANTEED PASS— You get your FCC License or money refunded. Send for FREE facts now. 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For at «inu order i [eauinn jotoyouianeamSfj'i.lHlloi less rh,in Ml minutes work For at iinu order repair job you c n'neamovej S 1 00.04 1 Fbff information package call or write: Toll-Free 1-800-537-0589 Viejo Publications, Inc. 5329 Fountain Ave., Dept. REC Los Angeles, CA 90029 CIRCLE 196 ON FREE INFORMATION CARD CIRCLE 108 ON FREE INFORMATION CARD BUILD THIS How good is your amplifier? Our inexpensive THD analyzer will let you know. JOHN R KEIDEL HAVE YOU EVER WONDERED EXACTLY how good an amplifier is. or whether it actually measures up to the manufacturers specifica- tion of its Total Harmonic Distor- tion, or THD? Or are you curious if the amplifier you've designed Is better or worse than a store- bought one? If the answer is yes to any of those questions, then you should build our inexpensive THD analyzer. You can use it to test "home-brew" amplifier breadboard circuits or commer- cial equipment such as stereo re- ceivers, preamps, and power amps. The analyzer uses an ui- tra-pure 1-kHz test signal to mea- sure THD at a user-selected ANALYZER voltage level for voltage ampli- fiers, or a desired power level for checking power amps up to 600 watts. It will detect THD levels down to 0.005 percent! It fea- tures a built-in one-percent THD calibrator, a full array of input and output processing controls, and uses your digital multimeter (DMM) as a readout device. Circuit description As shown in Fig. 1, an NE5534N low-noise, low-distor- tion op-amp, IC 1 , is configured as a Wien Bridge sine-wave os- cillator. Carefully matched RC values (R2-C1 and R3-C2) in the frequency-selective positive feed- back network contribute to its low distortion level. Resistor Rl and bulb LMP1 form the sta- bilized negative feedback net- work that provides a constant- amplitude output signal. DC off- set control R4 keeps DC current out of LMP1. which minimizes second harmonic distortion con- tent. Filter network R6-C6 fur- ther reduces any residual distor- tion. After passing through fixed and variable attenuators, plus a buffer amp (IC2), the signal emerges at output jack JL The output signal from Jl driv- es the input of the device under test (DUT), usually an amplifier. The DUT's output, which in- cludes some degree of distortion, is applied to the input of the ana- lyzer at jack J2. The fundamental frequency (1 kHz) is then re- moved from the output signal of the DUT, leaving only harmonic distortion components. Combination notch/high-pass filter circuits IC3 and IC4 (both TL074s) perform the removal function. One feature of IC3's three-stage RC active filter is that it maintains a constant 45-dB notch depth over its full tuning range. The filter is connected in series with an identical second filter (IC4). to provide a 90-dB notch of the fundamental signal. The resultant frequency re- sponse of the combined filters is 27 dB down at 20 Hz, which helps suppress 60-Hz hum and o m o m 2 CD m 3D 47 o z o (T H O LU -1 LU 6 o s R16 10K R20 9.09K R23 5.1 K 7.5K C10^ .001 optional bct. EARTH GND. RG. 1— SCHEMATIC DIAGRAM of the simple THD analyzer. An NE5534N op-amp (IC1) is configured as a Wien Bridge sine wave oscillator. Carefully matched RC values in the frequency-selective positive feedback network contribute to the low distortion level. 48 Resistor R1 and incandescent bulb LMP1 form the stabilized negative feedback network that provides a constant-amplitude output signal. other low-frequency noises. Above the 90-dB notch frequen- cy, the response is flat ( ± 0.5 dB) from 2 kHz to 100 kHz. When S4, the thd/ref switch, is in the thd position, a signal containing only THD compo- nents is channeled through from the output of the xl/xlO THD amp (IC4) to the input of the AC- to-DC converter, IC5. Although both polarities of the applied sig- nal are rectified by this circuit, only the positive averaged signal is fed to the low-pass filter R41- C20, The output buffer. IC6, is a CA3 194 precision op-amp, stable enough to provide accurate volt, millivolt, and microvolt DC level output signals to an external DVM. Dual op-amp 1C9, a CA3260, serves as a calibrator. The first stage affords precision half-wave rectification of the master os- cillator's signal. That same ap- plied signal is AC coupled by C30 to the second stage, biased at V-z V cc , for linear transfer to its out- put. Voltage divider R49-R50 mixes a very small portion of half- wave output at pin 7 of IC9 with a much larger full sine wave seen at pin 1. Since the signal swings slightly more positive from its quiescent level than it does in the negative-going direction, it is considered to have a specific amount of second harmonic dis- tortion. That amount, by design, is one percent. Wall transformer Tl feeds half- wave power diodes D4 and D5 through connector J4, fuse Fl, and power switch S5. Capacitors C22 and C25 are the principal filters for the positive and nega- tive supplies, respectively Small- er filters, C23 and C27, along with high-frequency transient suppressors C24 and C28. are in- cluded at the output side of reg- ulators IC7 (a 7815 +15-volt regulator) and IC8 [a 7915 -15- volt regulator). Construction Breadboard assembly of the analyzer is not recommended, al- though a seasoned builder may wish to attempt it. It's best to ei- ther make your own PC board from the foil pattern we've pro- vided, or order one from source mentioned in the parts list. Mount all components as shown in Fig. 2. Check orienta- FOIL PATTERN for the THD meter shown actual size. tion of all polarized parts as you install them, and the use of IC sockets is suggested. All power- line wiring, including the LED1 indicator, uses two wires plus a shield. Connect the shield wires s I m 33 49 J8 ^ EARTH O LED1 03 o z O c H u UJ J4 -® POWER IN SOLDER TO FRAME 0FR10 FIG. 2— PARTS PLACEMENT DIAGRAM. Note that JUT is actually an 8-pin DIP socket in which a jumper Is placed in either the far-left or -right side (see text). Also note the six components soldered to the front-panel-mounted controls. together and then to ground, to prevent hum pick-up. Also, ground the frame of potentiome- ter RIO. Bare ground wires for each BNC connector may be wrapped around the connector body prior to installing the re- taining nut. The ground binding post (J8) on the rear panel pro- vides an optional, external earth- ground connection when mea- suring microvolt-level THD sig- nals. Just connect J8 to circuit ground. The grommet used to hold bulb LMP1 should have a 54- inch inside diameter. It is glued to the top side over the hole for maximum resiliency. In addition to the components that are soldered to the circuit board, also note that five re- sistors and one capacitor are sol- dered across the terminals of panel-mounted controls SI, RIO, S2, and J2 (see Fig. 2), Capacitors CI and C2 must be matched to better tolerances than their marked 1% values. If you don't own or can't borrow a capacitance meter, you can build and use the simple circuit shown in Fig. 3. Adjust the calibration potentiometer with any one of the four 0.01 uJF capacitors (CI, C2, Cll, or C13) inserted as C x . to read 1.000 volt on your DMM's 2-volt DC range. (You can consid- er the reading to be 0.01000 |xF.) Now measure the remaining three capacitors and select the two that are closest in value. Ab- solute value is not important; we simply want them to be the same value. However, if one capacitor measures 80 pF lower than an- other, you can solder an 82-pF mica capacitor on the underside of the PC board in parallel with the selected capacitor. The left- over 1% 0.01 u,F capacitors can be used for Cll and CI3 without having to be closely matched. Likewise, resistors R2 and R3 must be close in value. Using your DMM on its 20K resistance range, select two 15. 8K resistors that are the closest in value. If the match is less than perfect, solder a small-value resistor in series with the lower value to raise it to the exact value of the higher one. You can mount two resistors in place of one by putting one through each hole in the board and soldering the raised ends to- gether. Again, the leftover 1% 15. 8K resistors can be used for R18 and R27 without having to be closely matched. You may wish to build your own enclosure for the THD meter. A silk-screened front panel mea- suring 9 3 /4 inches wide by 3 inches high can be purchased from the source mentioned in the parts list. If you decide to pur- chase the front panel, and build your own enclosure, build it to fit the front panel and drill several V* -inch holes in the top panel near the voltage regulators to allow heat to escape. Otherwise you can purchase the same enclosure used for the prototype; the exact 50 PARTS LIST All resistors are Vi watt, 5%, unless R46— 680 ohms LED1— Red light-emitting diode otherwise indicated. R50— 249 ohms, 1%, metal film Other components R1— 430 ohms R51, R52— 100,000 ohms, 1%, metal S1 — Panel-mount, 2-pole, 6-position R?, R3, R18, R?7— 15,800 ohms, film switch 1%, metal film Capacitors S2, S4-S6 — Panel-mount miniature R4 — 100, 000 ohms, PC-mount C1, C2, C11, C13— 0.01 m.F, 100 volts, SPDT toggle switch potentiometer 1% Mylar S3— Not used R5— 22,000 ohms C3, C7, C15—22 pF. 300 volts, mica JU1 — 8-pin DIP socket or jumper R6, R11, R15, R34, R36— 1000 ohms C4, C5— 10 jjlF, 25 volts, tantalum block R7— 20,000 ohms C6, C8, C20, C29, C32— 0.1 |aF, 50 T1— 120VAC24VAC, 200 mA wall R8. R48— 2000 ohms volts, Mylar transformer R9— 220 ohms C9, C14, C21, C30— 0.01 jjlF, 50 J1^J3, J5— Panel-mount male BNC R10 — 50,000 ohms, panel-mount volts, Mylar connector potentiometer C10, C12— 0.001 fiF, 100 volts, 1% J4 — Coaxial power input jack R10A— 5600 ohms Mylar J6-J8 — Pane I -mount binding post R12, R45— 620 ohms C16, C17— 0.2 nF 50 volts, Mylar LMP1— Incandescent bulb, #327 R13, R35— 100,000 ohms C18, C19, C23, C27— 1.0 n.F, 25 F1— Fuse, 0.5A, 120 VAC R14— 11,000 ohms volts, tantalum Miscellaneous: Project case (Jam- R16, R17, R24, R25, R38, R39, C22, C25— 220 p-F 50 volts, eco Electronics H2507), two Yz- R49— 10,000 ohms, 1%, metal film electrolytic inch diameter instrument knobs, R19, R26— 5100 ohms C24, C28— 0.33 jjlF, 50 volts, Mylar seven 8-pin IC sockets, (not includ- R20, R31— 9090 ohms, 1%, metal C26— 1 iaF, 50 volts, tantalum ing JU1), fuse holder, LED bezel, film C31— 100 jxF, 25 volts, electrolytic grommet, shielded cable, wire, sol- R21, R29— 130,000 ohms Semiconductors der, hardware, etc. R22, R30— 50,000 ohms, PC-mount IC1, IC2, IC5— NE5534N low-noise Note: The following items are potentiometer op-amp available from Instrumex, P.O. R23, R28— 7500 ohms iC3, IC4— TL074 quad low-noise Box 490, Blue Bell, PA 19422: R32— 2000 ohms, 1%, metal film op-amp • Etched, drilled, and plated PC R33— 18,200 ohms, 1%, metal film IC6 — CA31 93E precision op-amp board and silk-screened plastic R37 — 10 megohms R40— 4530 ohms, 1%, metal film R41, R42— 1 megohm R43— 10,000 ohms, PC-mount potentiometer R44, R47, R53, R54— 10,000 ohms !C7 — 7815 positive 15-volt regulator IC8 — 7915 negative 15-volt regulator IC9— CA3260E dual MOSFET-input op-amp D1,D2— 1N914diode D3-D5— 1N4002 diode front panel {both to fit case men- tioned above — $25.00 + $3.00 S&H PA residents must include 6% sales tax. Allow 2-4 weeks for delivery- model number is listed in the parts list, and the front panel is designed to fit it perfectly. Figure 4 shows the completed prototype. Adjustments Using a DMM on its millivolt- DC range, connect it between pin 6 of IC1 and ground. Adjust R4 for a reading of 000.0 mV on the meter. Next, set the input switch (S2) to ">20V," the thd amp switch (S4) to "xlO," and the thd/ref switch (S5) to "THD." With the DMM still set to read millivolts DC, connect its leads across the + and - DVM binding posts ( J6 and J7) and adjust R43 for a reading of 000.0 mV on the meter. Filter-null adjustments may be made with an oscilloscope or DMM on its lowest AC voltage range (typically 2 volts). Insert a jumper in the JU1 jumper block (null-oper) in the left- most posi- tion when facing the front panel (next to R22, or the "null" posi- C1 +12V + 12V i, 1\ IC1-3 rC 14[VjCA4011BE 03 001 fiF B4 10K ^T R2 Jfc C2 50K ■-WS- R1 IC1-b CAl. 18K V'CMOI IBE K3 ac R3 470K 1HF+12V R5 100K i a DVM IC1-d ^ 2VDC V-iCMO-nBE range 12r 11 13 IC1-C '.■■.; CA4011 BE r oH^-o- FIG. 3— HERE'S A ONE-IC CAPACITANCE TESTER used to match CI and C2. See text for details. tion). Connect a short coaxial ca- ble between output jack Jl and input jack J2. With power on, and S2 in the "<20V" position, S4 in the x 1 position, S5 in the "THD" position, and the rotary atten-db switch (SI) and var potentiometer (R10) in the mini- mum attenuation position, or fully counter-clockwise. Connect a scope or voltmeter to the IC4-pin-7 side of R31, and connect the ground lead to any ground in the area. If you"re using a scope, set volts/div switch (on the scope) to any posi- tion between 5 and 50 mV/div. ^ Carefully adjust potentiometer rn R30 for the best null on a scope ra screen, or lowest reading on a 3 meter. ^ Transfer the test probe to the 2 51 tfi O Z o en h- o FIG. 4— THE COMPLETED PROTOTYPE. Notice how the incandescent bulb (LMP1) is protected from damage by a rubber grommet. IC3-pin-l side of R20. Adjust R22 for a minimum reading on the scope CRT or voltmeter. Insert a jumper in the C12 side of the JU1 jumper block. You may be able to squeeze 1 or 2 dB more null from the system by shifting the DMM to the DVM binding posts ( J6 and J7), setting the meter to its 200 mV DC range, setting S4 to x 10, and trimming the adjustments of R22 and R30. Checkout and use Connect a scope or DMM set to read AC volts to output jack Jl„ Rotate SI and RIO; the output signal voltage should vary ac- cordingly. Remember that the controls are attenuators, not gain controls, so maximum sig- nal occurs in the counterclock- wise position. Check the input p-p switch S2 by applying the signal from J I to J2, setting S5 to "REF," and mea- suring the AC output at J3. The output signal should be max- imum with S2 in the <20V posi- tion and minimum in the >20V position. It's important to note that if the input signal to J2 goes much higher than 20V peak to peak, and S2 is in the <20V posi- tion, clipping will begin to occur. You can use the analyzer's cal- ibrator to check all remaining functions, Connect a coaxial ca- ble from J3 to J2. Set all toggle switches to the upright posi- tions, and connect your DMM to J6 and J 7 set to read DC volts or millivolts, as required. Now, if the THD signal reads 24.0 mV, which is 0.024V, and you switch the S5 to "REE" the DMM should then read 2.40V, or a number very close to that. When the resulting fraction (0.024/2.4) is multiplied by 100 it should produce a THD percent figure of one percent. Figure 5 shows the test setup for THD measurements. Say that we are measuring percent THD of a 50-watt amplifier that's con- nected to an 8-ohm power re- sistor load. By ohms law, it will take 20 volts across 8 ohms to produce 50 watts. Now let's say confirmed on page 59 OUTPUT J1 mm SET DC VOLTS RANGE AS REQUIRED INPUT AMPLIFIER OR D.U.T. OUT SQ C- 1 POWER RESISTOR LOAD [IF REQ.t FIG. 5— BLOCK DIAGRAM OF TEST set- up. Most THD measurements can be made in this manner. THD MEASUREMENT When a pure or undistorted sine wave is applied to a circuit containing vacuum tubes, transistors, or op-amps, which is used to provide linear transfer of the sig- nal, some degree of distortion always ap- pears at the output. As the near-perfect sine wave travels through the device under test (OUT), its shape is altered due to inherent non- linearities within the circuit. Waveform al- teration is the equivalent of adding harmonics, or multiples of the fundamen- tal frequency, in varying phases and am- plitudes to the fundamental signal. It can be shown mathematically and by mea- surement that these spurious harmonic components are vested within the output signal's waveshape. Spectrum analyzers are used to sweep over the frequency range of interest, sep- arating the fundamental and its harmon- ics into individual signals. It provides a CRT display of these various signals, in- cluding odd and/or even harmonics in their proper amplitudes and frequency lo- cations relative to the fundamental. Sim- itar instruments use digital signal processing techniques rather than a sweep method to provide more in-depth data including phase angles. Wave analyzers are essentially tuned filters that include a measurement window that is manually frequency shifted through the range of interest. It offers meter-read- out amplitude measurements of the vari- ous harmonics relative to the fundamental frequency. THD analyzers are used to notch out the fundamental from the DUTs output signal leaving only the harmonic compo- nents intact. It then measures the sum total of the residual signals in terms of their RMS or average values, and com- pares them to the overall amplitude of the output signal which is taken as a 100 per- cent reference. The ratio of the THD mea- surement to the reference, multiplied by 100, equals the percent THD. R-E 52 BUILD THE BATTERY TOOL Get the mast out of your rechargeable batteries with this microcontroller- based battery discharger. FRED EADY TIMES HAVE CHANGED— YOU'D PROB- ably be surprised at the number of devices containing some sort of rechargeable battery that you use on a regular basis. Cordless phones, mixers, radio-controlled gear, emergency flashlights, cam- corders— and even vacuum cleaners — are just a few exam- ples. The list goes on, but let's just say that rechargeable bat- teries are popular because of their convenience and re- usability Because you pay more for rechargeable cells, and de- pend on them for extensive use, it is imperative that you get max- imum performance from them. But you can't do that unless you understand their physical nature. The secret to rechargeable bat- tery life and performance is prop- er conditioning and use. To condition a battery, you must dis- charge the internal cells to a pre- determined voltage that is well below the operating level of most electronic equipment and that is beyond the "knee" of the dis- charge curve. Ni-Cd batteries ex- hibit a linear discharge rate over the majority of their discharge cycle. However, at some point just before full discharge, the voltage drops off sharply. That sharp downturn in voltage is called the "knee" (see Fig. 1). Conditioning allows charged electrode material, that is not normally used, to be discharged or "exercised" to prevent pre- mature battery-voltage droop, or kneeing. The premature voltage droop, or premature knee, is commonly mistaken for the bat- tery malady known as "memory. " Memory is virtually impossible to create during typical battery use. It takes laboratory-grade equip- ment and multiple precise charges and discharges to create o m o m <: cc m I _i to 35 53 the memory effect. The perfor- mance degradation you perceive as battery memory is actually due to the fact that not all of the charged electrode material in the cells of the battery is available for use by your equipment. That is, the battery has not been cycled, or discharged, sufficiently. To properly facilitate the cyc- ling process, the battery dis- charge current and end-point battery cutoff voltage must be carefully monitored to avoid damaging the cells. There are three ways to accomplish this: First, you purchase expensive laboratory-grade equipment spe- cifically made for the purpose. Second, you can set aside a day and cycle the battery manually But third, you can use the inex- pensive, easy to build Battery Tool. The Battery Tool is a micro- controller-based instrument that performs a controlled, user-deter- mined, constant-current dis- charge on any type of rechargea- ble battery. Battery voltage can be as high as 18 volts, and the max- imum discharge current can be set as high as 1.5 amperes. .These maximums will accommodate most consumer batteries now in use. The Battery Tool monitors battery voltage and regulates the user-selected load current during the entire discharge cycle. Using the accompanying terminal pro- gram, you can determine such real-time parameters as 50% bat- tery life voltage, 0% battery life voltage, battery capacity, knee voltage, and battery voltage un- der load. The Battery Tool also provides elapsed time and initial no-load battery voltage readings. Since a history of battery per- formance is vital to determining when the battery is fully dis- charged or will not be able to pro- vide useful service, the Battery Tool terminal program can save all of the above parameters to a disk file for retrieval and com- parison later. The data collected during discharge can also be used to plot a typical battery dis- o charge curve. If you're like most ? electronic experimenters, you K have a gaggle of Ni-Cd's and o chargers lying around. The Bat- jj tery Tool can help determine if o they are good or bad and, if they 5 are good, what their capabilities cc are. Another plus for the Battery -NO LOAD VOLTAGE I 50% VOLTAGE 1 KNEE VOLTAGE I 0% VOLTAGE TIME fig. 1— TYPICAL RECHARGEABLE BATTERY CURVE. Proper conditioning entails con- trolled nondestructive discharging of the cells to a predetermined voltage that is well below the operating voltage of most electronic equipment. BBBBB AAAAAA Mill! TTTTTT EEEEEE RRRRR YY YY BB BB AA AA TT TT EE RR RR Y Y BBBBBB AAAAAA TT TT EEEE RRRRR YY BB BB AA AA TT TT EE RR R YY BBBBB AA AA TT TT EEEEEE RR RR YY TTTTTT 000000 000000 LL TT 00 00 00 00 LL TT 00 00 00 00 LL TT 00 00 00 00 LL TT 000000 000000 LLLLLL NiCad Battery Analyzer ****************************************************** * * ** * ***** ** ** ************ TEST CURRENT ELAPSED TIME 50% CAPACITY VOLTAGE 0% CAPACITY VOLTAGE KNEE VOLTAGE BATTERY CAPACITY NO-LOAD VOLTAGE CUTOFF VOLTAGE TEST RESULTS FOR BATTERY Spack PRESS ANY KEY TO RETURN... FIG. 2— A COMPLETED BATTERY TOOL TEST. All of the parameters are saved in a file to compile a history of battery performance. TEST DATE ==> 12-31-1990 =»> 1500 mA ==> 01:14:29 ==> 9.25 ==> 6.94 ==> 9.10 ==> 1850.00 mA-tiours ==> 10.S5 Volts ==> 7.20 Volts Tool is that you can build it for less than $100. What does it all mean? Figure 2 shows a completed Battery Tool test. Note that all of the parameters are included and saved in a file. The idea is to com- pile a history of battery perfor- mance. As the battery wears out, or if you accidentally abuse it, you can retrieve the history and determine just how much wear or damage has resulted. By using the Battery Tool, you'll never again have to guess about the condition of a particular re- chargeable battery. Let's talk about what all those real-time event readings tell you. The "test current" is the am- perage drawn from the battery during the test, "Elapsed time" is the time it took to run the test. The "50% capacity voltage" repre- sents both the average overall battery voltage during a test and the voltage at the point where half of the battery's useful charge is left. The 50% value is depen- dent upon the cutoff voltage you specify. Use your best judgment or, better yet, consult the man- ufacturer's recommendations when selecting your battery's cut- off voltage. The "0% capacity voltage" is a calculated measurement that 54 FIG. 3— THE BATTERY TOOL IS BASED ON AN 8749H microcontroller that performs serial I/O, analog-to-digital processing, and battery monitoring functions. A MAX233 converts TTL voltage levels to RS-232-C voltage levels and vice versa to simplify the serial interface between the Battery Tool and the terminal program. projects the probable voltage un- der load that would be read when all usable battery energy is de- pleted. The projected reading is based on conventional Ni-Cd bat- tery formulas involving the 50% calculation. The zero-capacity condition should occur after the knee has formed. The "knee voltage" defines the voltage point at which the characteristic knee will occur. The value is calculated by taking into account the 50% battery voltage versus time. The "battery capacity" is just that. That is, if you were to look at your particular cells closely you would find a manufacturers ca- pacity rating or rated cell capaci- ty. On a AA Ni-Cd cell that's usually between 450 to 550 milli- ampere-hours. That says under normal temperature and load conditions, the cell should be able to deliver the rated current for 1 hour. That may be true for new cells, but wear and misuse can reduce the performance fig- ure. The Battery Tool gives you the real-world performance fig- ures so you can most effectively use the chemical energy supplied by the battery. The Battery Tool calculates battery capacity every 60 seconds using the user-de- fined load current versus time. The "battery no-load voltage" is the voltage measured with the battery at rest with no resistive load applied. Its only purpose is to give the user an indication of what the battery voltage is before loading. Theory of operation As shown in Fig. 3, the Battery Tool is based on IC2. an 8749H microcontroller, running at a clock speed of 10 MHz. The 8749H performs serial I/O, ana- log-to-digital processing, and battery- monitoring functions, as well as supplying the clock source for the analog-to-digital converter by executing a program contained in its internal EPROM. The 8749H is reset via SI and C6. Note that we ran a story on an 874X-series microcontroller pro- grammer (see Radio-Elec- tronics. November 1991). A MAX233. IC1. converts TTL voltage levels to RS-232-C voltage levels and vice versa to simplify the serial interface between the Battery Tool and the terminal program. Note that no external charge-pump capacitors or power supplies are needed to generate the necessary negative RS-232 voltages as with other RS-232 devices. An ADC0809 8-channel, 8-bit analog- to-digital (A/D) converter (IC3) monitors voltage levels from the battery under test. Micro- controller 1C2 initiates a voltage or current measurement by se- lecting IC3s channel (ino, pin 26) for current readings or chan- nel 1 (in), pin 27) for voltage read- ings by applying a low or high respectively to pin 25 (ao) of IC3 . Depending upon whether cur- rent or voltage is to be measured, IC2 also selects the correct refer- ence voltage for pin 12 of IC3 by turning reference-switch tran- sistor Ql on and off — Ql is turned on for current measure- ments and off for voltage mea- surements. The reference volt- age — either +5.00 volts for voltage measurements or \ 2.56 volts for current measure- ments — is generated by potenti- ometers R2 and R3, resistor Rl, bypass capacitor C3, and varia- ble voltage regulator IC6 (an LM317LZ). To initiate a reading, IC2 si- multaneously applies a high pulse to IC3s ale and start pins 22 and 6. Once IC3 reads the ap- propriate voltage input at either pin 26 (current) or pin 27 (volt- age), it performs an internal A/D conversion. When conversion is complete, IC3 signals IC2 that the 8 bits of converted analog data on its bus are valid by rais- ing pin 7 (eoc, or End Of Con- o m o m DO m 55 TO DB-25 CONNECTOR (J3) CO z o s O HI O Q < rx PRI g 120 VAC FIG. 4— PARTS-PLACEMENT DIAGRAM. MOSFET Q2 can be bent over and mounted on the heatsink pad along with IC5 if you intend to monitor batteries with four cells or less but must be insulated from the pad. If you will be monitoring battery packs with more than four cells, 02 requires more substantial heatsinking (see text). version). The data that is sampled by IC2 is either used by IC2 or sent in raw 8-bit form to the terminal program via IC1 for further processing. Because IC3 can measure only voltages, it is necessary to derive current readings from known voltages and resistances. Since we are looking for a resultant cur- rent, voltage and resistance must be constants. Ohm's Law says that current is equal to voltage divided by resistance, or I = E/R. So, if we are measuring current, and 1C3 measures 1 volt across RIO, which in our case is 1 ohm. Ohm's Law says that I = 1/1, re- sulting in 1 amp flowing through RIO. The 8-bit representation of 1 volt generated by IC3 causes IC2 to vary the resistance of MOSFET Q2 and regulate the load current. Because, as mentioned before, IC3 is a voltage-measuring de- vice, voltage measurements— as opposed to current measure- ments — are more straightfor- ward. Resistors Rll— R13 make up a low-power precision voltage divider that is placed across the battery's positive and negative terminals. The voltage-divider re- sistances were selected with two design points in mind: First, to draw insignificant current from the battery under test, and sec- ond, to divide the battery voltage by 4. In this application IC3 has a voltage-measurement range of to +5 volts DC. That restriction would severely hamper the usefulness of the Battery Tool, so the R11-R13 voltage divider is used to prescale the output data provided by IC3. Note that 1C3 can resolve to 256 discrete steps including step (0 volts DC). When the reference voltage at pin 12 of IC3 is +5 volts, each voltage step resolved by IC3 is + 5 volts divided by 256 steps, or 0.0195 volts per step. The prescaling enables IC3 to effectively read a minimum of volts DC and a maximum of + 20 volts DC. The terminal program processes the 8 bits of sampled data and computes the corre- sponding battery voltage which is displayed to you in real time. The maximum allowed battery voltage is also controlled by the terminal program. Also, IC2 uses the voltage data to determine if the preset cutoff voltage has been reached. If the battery under test exceeds 18 volts, the terminal program immediately removes the resistive load from the battery and halts the test. With respect to current read- ings, each digital step is 0.01 volts, because of the 2.56-volt ref- erence, so a maximum current of 2,56 amperes can be sensed. The limiting factor as to how much load current can be applied is de- pendent upon the power dissipa- tion capacity of power resistor R10. The terminal program lim- its the operating test current to 1.5 amperes, which falls safely within the 5-watt dissipation rat- ing of R10. It would be impossible to get PARTS LISTS All resistors are VS watt, 5%, unless otherwise noted R1— 240 ohms R2, R3— 1000 ohms, potentiometer R4 — 1000 ohms R5. R6 100,000 ohms R7, R8— 10 megohms R9— 10, 000 ohms R10— 1 ohm, 5 watts, t% R1 1—20,000 ohms, 1% R12, R13— 10,000 ohms, 1% Capacitors C1 — 1000 m-F. 16 volts, electrolytic C2, C3. C8, C9— 0.1 )iF, ceramic C4, C5 — 27 pF, ceramic disk C6— 1 n-F. 16 volts, tantalum electrolytic C7— 1 (J.F, metal film Semiconductors IC1— MAX233 RS-232 driver 1C2— 8749H microcontroller IC3— ADC0809 8-channel 8-bit A/D converter IC4 — LM3900 quad op-amp IC5— 7805 5-vo!t regulator IC6— LM317LZ adjustable regulator D1— 1N4001 diode D2— 1N914diode Q1— PN2222A NPN transistor Q2— IRFZ22 MOSFET Other components S1— SPST momentary pushbutton switch XTAL1— 10 MHz crystal J1, J2 — red and black banana jacks (or whatever best suits your needs) J3 — female DB-25 connector Miscellaneous: PC board, case, 18- gauge wire, heatsink (see text), 9-12 VAC 1-amp transformer, ribbon cable, hardware, tC sockets, solder, etc. Note: The following items are available from Fred Eady, 1320 Anchor Lane, Merritt Island, FL 32952: • Kit of parts with a programmed mi- crocontroller and PC board (not in- cluding connectors, heatsink, and case)— $89.00+ $2.50 S&H • Programmed microcontroller only— $20.00 + $2.50 S&H • PC board only— $25. 00 + $2.50 S&H • Software on a SVWnch disk — $5 postpaid any accurate voltage or current measurements from any battery if the load current was not main- tained at a constant value. Re- member that if any of the three values used in Ohm's Law change, all others are affected. So, to get maximum measure- ment accuracy, IC2, IC4, and Q2, along with resistors R5— R9, blocking diode D2, and capacitor C7, form a low-drift ramp-and- hold circuit. Here's how thai circuit works. The first gate of IC4 (lC4-a) pro- vides a very low input bias cur- rent to the input of the second gate, IC4-b. The bias gate elimi- 56 FIG. 5— THE AUTHOR'S PROTOTYPE. Notice how MOSf ET Q2 is mounted on a separate heatsink. (You certainly don't need such a big heatsink; use whatever you have on hand, which is what the author did.) nates the need for FET tran- sistors and special-purpose inte- grated circuits normally needed for sensitive ramp-and-hold ap- plications. The matched ampli- fiers found in the LM3900 op- amp are also helpful in this area. Microcontroller 1C2 supplies either a high or low TTL voltage level to resistors R5 and R6 via output port pins 22 and 23. (Note that, in Fig. 3, R5 is marked "up" and R6 is marked "down.") When a low TTL level is applied to both R5 and R6, the ramp and hold circuit is in the hold state. Thus the voltage at 1C4 output pin 5 is stable. The higher the quality of capacitor C7, the less voltage drift at pin 5. Applying a TTL high to R5 while holding R6 low causes the voltage at pin 5 of IC4 to rise. Conversely, applying a TTL high to R6 while holding R5 low decreases the voltage at pin 5 of IC4. The output voltage at pin 5 of IC4 is fed through R9 to the gate of Q2, an insulated-gate MOSFET power transistor; think of Q2 as simply a high-wattage potenti- ometer whose wiper is the voltage supplied by IC4. As the voltage on the gate of Q2 increases, the re- sistance between Q2's drain and source decreases, and vice versa. A high-wattage precision voltage divider is formed by Q2 and pre- cision power resistor RIO. By Ohm's Law, we know that current is constant in a series of resis- tances while voltage differs at each resistance node. Now comes the good part: if we measure the voltage across the 1-ohm preci- sion resistor and control the volt- age drop across it using Q2, we can produce a constant load across a battery independent of the battery's voltage and operat- ing temperature. In summary, the user tells IC2 via the terminal program what load current to place on the bat- tery under test. Microcontroller IC2 ramps the battery up to the selected current by reading the voltage drop across RIO that is monitored by IC3. The sampled voltage drop is compared to the user-selected load-current value (actually a converted voltage drop value) sent to it by the terminal program. If the sampled voltage drop (current) reading is too high, a "down" command is sent to the ramp and hold circuit thus increasing the resistance across the drain and source of Q2. thereby reducing the voltage drop across RIO. That of course has the effect of lowering the cur- rent across the precision voltage divider formed by Q2 and RIO. The opposite is true if the com- parison is too low. The process takes place hundreds of times per second providing a varying resistance able to track a varying voltage, resulting in a constant current independent of the bat- tery voltage. Construction Using the supplied foil pat- terns, you can make your own PC board. If you would prefer not to make your own, a professionally prepared PC board is available — see the parts list. Following Fig 4 as a guide, begin assembly by in- stalling voltage regulator IC5, rectifier diode Dl, filter capacitor CI, and decoupling capacitor C2, Note that IC5 should be bolted down to lie flat against the heat- sink pad on the PC board. Tem- porarily connect a 9-12 VAC, 1- amp source to the pads indicated in Fig. 4 and apply power; there should be + 5 volts DC at the out- put (pin 3) of regulator IC5. Re- move power and install IC6, R1-R4, Ql, and C3. observing proper orientation of Ql and ICO. To perform reference-voltage calibration, connect ajumper be- tween the end of R4 that is not connected to the base of Ql and ground. Grounding R4 will as- sure that Ql is off and allows the adjustment of R3 for -I- 5.00 volts at the output of IC6; apply power and make the adjustment. After adjusting R3, disconnect the grounded end of the jumper and connect it to the +5-volt output a of IC5; that turns Ql on and % places potentiometers R2 and R3 Eg in parallel. Adjust R2 for a read- i ing of + 2.56 volts DC at the out- 3 put (pin 2) of IC6. Recheck both £ the +5.00- and the +2.56-volt - 57 w o I o D < CE adjustments until you can alter- nate between them by moving the jumper without further adjust- ments to either R2 or R3. Remove power and the jumper before pro- ceeding any further. Install components IC2, XTAL1, and C4---C6. You may also temporarily connect reset switch SI at this time. Once again apply power and, using a logic probe, check for oscillation at pin 11 of IC2; if it doesn't oscillate, check power connections, the clock cir- cuit (consisting of XTALI, C4, and C5), and make sure SI is not closed. If pin 11 is oscillating, check to see that the oscillation stops when SI is closed. Oscilla- tion at pin 11 of IC2 indicates that the IC is operating properly. Complete the board by mount- ing IC3, IC4. R5-RI3, C7, and D2. Recheck the reference volt- ages at pin 12 of IC3. Mount IC1 and assemble the serial cable ac- cording to your needs. Most of you will use a DB-25 IDC (Insula- tion Displacement Connector) connector and 3 strands of rib- bon cable connected between the points indicated in Fig. 4 and pins 2 (serial in), 3 (serial out), and 7 {signal ground) of DB-25 connector Jl. Note that MOSFET Q2 must be heatsinked. If you intend to monitor batteries with four cells or less, Q2 can be bent over and mounted on the heatsink pad along with IC5. BUT, if you do that, Q 2 must be insulated from the pad because its metal tab gets connected directly to the positive terminal of the battery under test, while the 7805 s tab is at ground potential. If you will be monitoring battery packs with more than four cells, Q2 requires more substantial heatsinking than just the foil pad. In that case, you can either mount Q2 on the board, along with a suitable heatsink, or mount it off the board on a heatsink and wire it to the appropriate PC pads as was done with the prototype shown in Fig. 5, Keep in mind that the larger the heatsink, the cooler the MOSFET runs, and the more stable the MOSFET's operation will be. Install a solder lug on the heat- sink tab of Q2 and solder a length of 18-gauge wire from the lug to a connector of your choice; the connector is for the positive ter- 9 9 9 9 9 99 9 9 □ 9 O e 9 00OO00O009990999 9 99D 9 9 0- 9 9 r 9 0^9009099999999099 9 —7 *T ^ 9 e 0~O00O O s° 9 o 1 D 9 -%si~ Vt» 00000000 on D 99909 o o O09999O OO009O9999 a oee ooooooo c > -^ 1 o e o O o o o o 9 000 9 99 ■ ■ 1° ■ oo o •1 OO -3 15 /ie INCHES- COMPONENT SIDE oi the Battery Tool PC board. minal of the battery under test. The prototype uses standard red and black banana jacks for the battery receptacles, although you can use whatever you like. Solder a second piece of 18-gauge wire from the ground pad on the printed circuit board to the other battery connector. You can install the Battery Tool in a suitable case if desired. The prototype is housed in a 10"x8"x3" 2-piece plastic case. The banana jacks and the reset switch are mounted on the top panel, although the layout is not critical. The serial cable and AC power cable can enter the rear of the case. As shown in the sche- matic, you can install the op- tional diode and buzzer across the input jacks to indicate that the battery under test is con- nected with the wrong polarity. Using the Battery Tool Use of the Battery Tool is sim- ple. The terminal program called TOOL. EXE, which is available on the RE-BBS (516 293-2283, 1200/2400, 8N1) as part of a self- extracting ZIP file called BAT- TOOL. EXE, prompts you through the entire process. (After downloading the file, simply type "BATTOOL.EXE," and the file will unzip itself.) The ZIP file also contains the code for the micro- controller (TOOL, ASM), in case you want to program your own, although a programmed micro- controller is included in the parts kit. All of the software is also available on a 5 '/4-inch floppy 58 -3 ,s /ie INCHES - SOLDER SIDE of the Battery Tool PC board. disk (see the parts list), for those of you with no modem. Run the terminal program, ap- ply power to the Battery Tool, con- nect the battery you wish to test, and enter the battery cutoff volt- age and load current. Within 20 seconds you should see an elap- sed-time indication followed by a full screen of real-time events that were described earlier. When the battery is discharged to the cutoff voltage you specified, the discharge process is halted, the load is removed from the battery under test, you are prompted for the correct time, and the final data is saved to a file. If for some reason the battery under test cannot supply your selected cur- rent, the terminal program noti- fies you and halts the test. The Battery Tool can be used to simulate a particular device by determining how much current the device draws, and dialing that load current into the Battery Tool and running a cycle on the related battery. Another use in- volves determining just how much charge or life is left in a battery. Using the history you compile on a certain battery, you can connect the battery in ques- tion to the Battery Tool, ramp up to the current specified by the history, and note the voltage at that point. Using the historic voltage readings, you should be able to determine how far into the discharge cycle you are. If you depend on rechargeable bat- teries, the Battery Tool will be a worthwhile tool. R-E THD ANALYZER continued from page 52 we drive the input of the ampli- fier with a 1-volt pure sine wave and we obtain the 20 volts re- quired at the output. Since 20 volts RMS is 56 volts peak-to- peak, S2 must be set to >20V. With S5 in "THD" position a read- ing of 1.4 mV (0.0014V) DC is ob- tained. In the "REF" position we read 2.00V. Always read the range on the DMM that affords the best resolution. Now make the calculation: 0.0014/2.00 x 100 equals 0.07 percent THD. Voltage amplifiers are mea- sured in the same manner, but without the requirement of a load resistor. Such amplifiers will probably show lower THD voltage readings. If the THD voltage is too low on the DMMs mV range, set S4 to "x 10." In this case, however, divide the displayed THD voltage by 10. For example, 0.8 mV on the meter is read as 0.08 mV, since it was amplified 10 times to 0,8 mV. If the measured THD percent is three times or more greater than the analyzer's measurement "floor," no correction of the mea- sured value is required. If it's less than three times, a good approx- imation of the true THD percent is gi ven by the formula D (PUT ) = VD^ (measured) - D' z (floor). That means if you measure a pre- amp's THD at 0.005%. and the measurement floor is 0.004%, the true THD of the preamp is 0.003%. Depending upon the depth of the notch and how closely the RC's in the oscillator's frequency selective network are matched, the "floor" should typically be 0.003 to 0.005%, You can check the "floor" value in the same way you measured the 1% THD cal- ibrator, explained earlier. Instead of using the calibrator signal, feed in a maximum signal level from output Jl. If you use the x 10 position, it may be neces- sary to connect J8 to an external earth ground. Finally, you should know that THD measurements above 10 percent are less accurate than those below 10 percent, since the reference includes distortion plus the fundamental— not just the fundamental. R-E o m o m m 33 59 In the concluding installment of this series, we discover the relationship between changing magnetic and electric fields- m g z O enclosed by the coil according to 60 E = - ■ v dt V olts) where s is the area of the coil, and the current induced in the coil is I = E/R. The negative sign is a re- sult of the standard use of the right hand rule and of energy conservation. Rather than apply the right hand rule directly, it's easier to use Lenz's law to deter- mine the direction of the elec- tromotive force. Lenz's law says that E, and hence I, will be in a direction in such a way to produce a magnetic field that tends to oppose the change in flux. If the negative sign where not included, the equation would say that an in- crease in flux would increase E, thus increasing the flux thus in- creasing E, and so on, giving an infinite amount of energy from an infinitely small change in $! The opposition is not complete since the induced current dies away rapidly due to the resis- tance once the driving flux is held stable. However, in superconduc- tors, R = and the induced cur- rent continues. E is independent of the. cause of the flux change. Flux change can occur in two basic ways: 1. The source of B could be moved, or in some way, the direc- tion or magnitude of B could be changed as in Fig. 1-a or 2. The coil could be moved, rotat- ed, or the area of the coil changed as in Fig. 1-b. As long as the time-rate of change of the enclosed flux is the same, the same amount of elec- tromotive force results. The fact that an E field is asso- ciated with the force on an elec- tric charge can be used to account for this force. The work per unit charge required to move the charge from point a to point b was discussed previously. Mov- ing the charge around the closed coil and relating this to Farady's result gives ^E-dL = E = dfjB-ds) — ^ffl — -(wits) . The charge doesn't have to be confined to a conductive coil, the equation is valid for any closed path. The curl of E is found by taking the limit of the ratio of FIG. 1— A CHANGING ENCLOSED MAGNETIC FLUX Induces an electromotive force. In (a), the driving current l d is Increased resulting in an increasing B field or flux in the area s, which induces an electric field E. This current produces a magnetic field that tends to oppose the change in B. In (b) the B field is held steady. The area of the coil and thus the flux enclosed by the coll is increased by moving the slide wire with velocity v. A charge on the slide wire experiences a force F = qv x B resulting in current I. This current produces a magnetic field that tends to oppose the increase in enclosed flux. fE-dL to the area enclosed as the coil is shrunk down around a point. VxE = lim lim (H ds- /d o ds The limiting value of the ratio is the time-rate of change of B at the point so VxE= -8B/at(V/m 2 =T/s). The d symbolism stresses the fact that the concern is only with the time-rate of change of B and not how B changes from one point in space to another. This is Fara- day's law and is one of Maxwell's equations. It says that a chang- ing magnetic field is associated with an electric field whose ap- parent rotation about a point is proportional to the time-rate of change of the magnetic field. Since the curl is not zero, an elec- tric field associated with a chang- ing magnetic field is therefore not conservative. Gauss' law plus Faraday's law gives a complete picture of an electric field. It has a divergence due to electric charge at a point and it has curl due to changing magnetic field at a point. If there is no charge there is no diver- gence; if there is no change in the B field, there is no curl. If we place E field test instruments (electric charges q) near a point with a changing B field, the charges tend to circle around the point. In any case, the force on a charge q is given by the Lorentz force law. Inductance In the case of a static B field, inductance was defined as L = $/ I. Fig. 2 shows a coil with chang- ing current I. A voltage E will be induced that tends to oppose the FIG. 2— SELF INDUCTANCE OF A COIL. As the current I changes the magnitude of B , th e ma g net! c f I u x en c I osed by t he coi I also changes proportionately. An elec- _ tromotive force and associated E field re- m suits that tends to oppose the change in I £fj and keep the flux constant. The Indue- S tance is the ratio of the change in flux to an ™ infinitesimal change in current. It is re- ^ lated to the geometry of the coil and any £ material present within that coil. m 61 change in I, and hence r/f>3/ ® /K © •+V i.ED/ C/KCLBO TO £D&E CO/VA/ECT&Z © *0. © */£US 2.M30SS © &/ZOI/M& FIG. 3— THIS IS THE REGULATOR NEEDED for a pulled-up field. The circuit monitors the state of the battery through a resistive divider and causes the voltage to change at the field terminal. up because a mismatch between the voltage and the alternator will cause a lot of damage. It's a given that the regulator will blow up but that's not too bad because you can build an- other one. The real problem comes from the fact that your alternator can get destroyed as well. That's not even too bad a problem if only the diodes have been trashed since you can re- place them for a minimal cost too — but if you've burned out the coils in the windings, you're looking at a whole lot of bucks. Before we get on with this, let me tell you that I've seen several alter- nators that had both sides of the field brought out to terminals but still had one of them tied internally to + V or ground. Be warned. Most British vehicles — both cars and motorcycles — use a pulled-up field and the basic charging system layout is shown in Fig. 2. One side of the field is tied to the positive side of the battery through a relay that's en- ergized when the ignition is turned on. The relay is needed because a permanent connection would mean that the alternator's field windings were connected across the electrical system all the time and, since they usually have a resistance of about 76 -2 %. M Cf f£S* FIG. 4 — THE FOIL PATTERN for our regulator circuit. It's shown here actual size. S/AtK. OAJ £>AStf&OAf& FIG. 5— PARTS-PLACEMENT DIAGRAM. Remember that Q3 should be mounted off the board on a heatsink and R10 and LED1 can be mounted on your dashboard. four ohms, the battery would drain completely in no time at all. Not a good thing. The circuit in Fig. 3 is the regulator needed in this case and it's designed to work with a pulled-up field. As you can see, the basic action of the circuit is to monitor the state of the battery through the resistive divider made up of R1, R2, R3. and potentiometer R10, and to cause the voltage to change at the terminal marked "FIELD." When the ignition is turned on, cur- rent flows through R5, turns on the home-made Darlington pair consist- ing of Q2 and Q3, and this sends current to the field windings of the alternator. When the engine starts and the alternator begins delivering current to the system, the resulting voltage is sampled through R2 and, at a point determined by the setting of R10. 01 begins to conduct and drops the voltage at the base of 02- That continued on page 79 LEARN VCR CLEANING/MAINTENANCE/REPAIR EARN UP TO $1000 A WEEK,WORKING PART TIME FROM YOUR OWN HOME! THE MONET MAKING OPPORTUNITY OF THE 1990S IF you are able to work with common small hand tools, and are familiar with basic electronics (i.e. able to use voltmeter, understand DC electronics). . . . IF you possess average mechanical ability, and have a VCR on which to practice and learn. . . .then we can teach YOU VCR maintenance and repair! FACT: up to 90% of ALL VCR malfunctions are due to simple MECHANICAL or ELECTRO-MECHANICAL breakdowns! FACT: over 77 million VCRs in use today nationwide! Average VCR needs service or repair every 12 to 18 months! 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M % - MONEY BACK GUARANTEE! iff A* ' QUANTITY DISCOUNTS! j$ j£ MASTER CARD/AMEX/VISA/C.O.D # * eza mm mm « 1 i tp Have make and model number of equipment used in you area ready CALL TOLL-FREE I 1-800-284-8432! 5 CABLE WAREHOUSE !s W 10117 West Oakland Park Blvd., M ffif Suite 515, Sunrise, FL333S1 Ltf rr WO FLORIDA SALES \S CIRCLE 193 ON FREE INFORMATION CARD 77 iiii'inim-MHi Efficiency and amplifier design LARRY KLEIN An audio amplifier of any de- sign can be considered a sort of complex electronic valve between the AC wall outlet and your speakers. The audio-signal voltages from the program sources serve as control signals that vary the much larger power-supply voltages and cur- rents provided by your local public utility. The power-supply section of an amplifier has the task of converting the AC supplied by a wall outlet to a direct current of the desired voltage and current capabilities. Limitations in a power supply's ability to deliver voltage and current ultimately deter- mine the amount of output power available to drive speakers. Of course, another potential limitation is the amount of current that the output transistors can handle. But today's high-power output transistors are rel- atively cheap compared to heavy- duty power-supply transformers and heat sinks — and certainly less bulky. Power supply performance What demands do we make on a power supply besides that of convert- ing AC to DC? Ideally it should be able to instantaneously supply all the current and voltage needed by the output transistors to produce the de- sired output wattage in the speaker load. A standard — if not particularly cost-effective — way to achieve that goal is to build in a power supply de- signed to stand up under any signal contingency. That means a massive power transformer with heavy low- resistance windings (around an ap- propriate core) capable of supplying the needed current, one or more heavy-duty bridge rectifiers, and very g large filter/reservoir capacitors that 2 are kept charged to a high-voltage § level to cope with transient peak volt- o age/current demands. A few au- la diophile amplifiers are built that way, ^ and their owners take pride in the fact 5 that they can't be lifted without risk of a: a hemia. The operating theory of a conven- tional power supply is somewhat sim- ilar to that of the standard home hot- water heater, A large storage tank of water is maintained at a high temper- ature against the time that several family members might decide to take a shower and/or run both the dish- washer and the washing machine. To guarantee enough hot water reserve for several persons to shower com- fortably (assuming they don't do it together), the storage tank would have to be bigger, the heating ele- ments larger, and/or the water hotter. The need to hold large amounts of water at a constant high temperature despite the intermittent usage makes the typical hot-water heater a ther- mally inefficient waster of both space and fuel. There are high-efficiency, on-demand, tankless hot-water sys- tems available on the market, but for some reason they've never become popular. Toward higher efficiency Supposing an amplifier designer set himself the goal of designing a more efficient and cost-effective power supply that would neverthe- less provide all the power needed for musical contingencies: How would he go about it? In much the same way that some hot-water system man- ufacturers did: He would have the power supply "turn on" only when required, and to the degree that it is needed, rather than running continu- ously at full output. Such an approach has significant advantages. Much of the thermal inefficiency of conven- tional amplifiers arises from the fact that the power output transistors are required to handle the full potential of the power supply even when the am- plifier is being driven to a very low output level, or when there is no out- put at all 1 Current flow through the output transistors creates the need for the large finned heat sinks that line the rear or side panels of conven- tional power amplifiers. The heat sinks radiate that wasted power and thereby protect the output devices against thermal breakdown and sta- bilize the operation of other circuit elements that are affected by high temperatures. Super efficiency Amplifiers with "smart" ortracking power supplies monitor the audio sig- nal level and continuously adjust the power-supply voltage to the levels needed to support the required out- put level. There are several high-effi- ciency designs that use this tech- nique. Soundcraftmen's "Vari- Portional" circuit was probably the first to reach the market. The Vari- Portional circuit uses a fixed -level, low-voltage power supply plus an "on-demand" signal-controlled high- voltage supply. Because of music's low average signal level, the amplifier operates as a low-power unit using its low-voltage supply 90% of the time. This means that the dissipation (heating) of the output stage is substantially reduced, since dissipation is drrectly propor- tional to the voltage applied across the output transistors. And even when a momentary signal peak turns on the high-voltage supply, its mo- ment-to-moment voltage level is raised no higher than necessary to handle the signal peak, rather than being constantly fully on as with con- ventional output circuits. Two other, smaller companies that use similar smart power supplies come to mind: QSC and Crest. About 10 years ago. Bob Carver introduced a "magnetic-field" power amplifier that startled the audio world by its ability to produce a total of 400 watts from a 9-pound, eVi-inch cube. It included several innovative design concepts that both reduced the size of its internal components and in- creased efficiency to unprecedented levels. The unconventional "magnet- ic field" power transformer operates with a solid-state phase-controlled 76 R-E Engineering Admart Rates: Ads are 2Y*"x2W, One insertion $995 each. Six insertions $950 each, twelve insertions $925 each. Closing date same as regular rate card. 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WPT PUBLICATIONS 7015 N.E. 61st Avenue Vancouver, WA 98661 Phone (206) 750-9933 CIRCLE 1&6 ON FREE INFORMATION CARD CIRCLE 177 ON FREE INFORMATION CARD CIRCLE 180 ON FREE INFORMATION CARD Triac in series with its primary. The Triac controls the voltage reaching the primary of the transformer in the same way that Triacs in tight dimmers adjust the voltage reaching a lamp bulb — except that it does so it under electronic rather than manual control. An isolating photocoupler sensing el- ement responds to voltage variations at the transformer secondary caused by changes in power demand, and adjusts the phase angle of the Triac to allow more or less AC to reach the transformer primary. At the trans- former secondary there are up to four separate bridge rectifiers that supply ± 25. 50, 80. or 125 volts to the out- put stages, also depending on the signal level. The extraordinary efficiency of the Carver design is due both to the vary- ing AC input to the "magnetic field" power transformer and the to the varying levels of power-supply volt- age, both of which are controlled by the moment-to-moment amplitude of the audio signal. A final note: I've not meant to imply in my discussion that high-efficiency in amplifiers necessarily correlates with their sonic quality — any more than it does in speakers. But, as with speakers, if you can get efficiency plus all the other desired properties, then it seems to me that high efficien- cy (meaning reduced size, cost, and heat radiation) is obviously the way to go. R-E DRAWING BOARD continued from page 77 causes the Darlington pair to turn off and cuts the current sent to the field windings. The alternator output will drop off which also turns off 01 . The voltage sampled by R10 will always be a fixed proportion of the system voltage but the ratio can change due to heat and other factors. Remember that the engine area of a bike or car is a really harsh environ- ment. If you find that to be a problem for you, replace R2 with aN 8 ±10 volt Zener diode. The fundamental switching action of the regulator circuit gets help from the positive feedback supplied by C3 and R6. When the Darlington starts to turn off. the voltage at its collector increases and some current flows through C3 and R6. The current at the base of 01 is the sum of the tapped system voltage through R10 and the feedback supplied through C3 and R6. That speeds up things to get to the point where Q1 will turn on and turn off the Darlington pair and shut down power to the Field. When that point is reached, C3 dumps the rest of its charge through R7 and R8 and the current flow in the field windings drops to zero. Diode D1 protects the Darlington pair from being damaged by the induced voltage that appears when the field current collapses. The knee of the voltage regulator is determined by the setting of R10, By adjusting the position of the potenti- ometer, you can change the voltage setting of the car's electrical system. The LED will provide a peace-of-mind indicator to let you know that the cir- cuit is working, but a flashing light can be annoying so, if you put it on the dashboard, use a small LED. The foil pattern for our regulator circuit is shown in Fig. 4. The reason for the multitude of connection points is because Q3 should be mounted outside the case on a heatsink for cooling. The board was also designed to have LED1 and potentiometer R10 mounted outside the case. If you're going to use the regulator in a car, it's nice to have them right on the dashboard near the voltage indicator. There are fingers on the PC board so the connections to the off-board components can be made with a handy-dandy edge connector on tenth-of-an-inch centers. 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DRJE129I O m no m 33 CD CO 83 COMPUTER CONNECTIONS 1991 Retrospective JEFF HM.TZMAN w o Z O DC 1- -i 6 Q < 84 This is the last calendar issue of the year: let's take a look at what happened and make some educated guesses about where things are going in the person- al computer industry. 1991 will be remembered as a turn- ing point in the history of personal computing. It was the tenth anniver- sary of the IBM PC. In 1981. the 4.77- MHz 8088 microprocessor though hardly leading edge was certainly much more powerful than the Z80's and 6502's most of us were used to. Today's high-end PC's offer magni- tude-of-order improvements over the original in bus speed, memory ad- dressing, disk storage, video resolu- tion, print resolution, and general expandability. Back then, networking was hardly out of the research labs; today it is ubiquitous. It's no longer a question of when or how the business scene will become networked, but what to do with that capability now that we've got it. This will be a huge growth area between now and the start of the next millennia. In 1981 the big companies were IBM, Apple, Microsoft, Borland, Ash- ton-Tate, and MicroPro. There was no Lotus, no Novell, no WordPerfect, IBM, Digital, and HP had no idea that their business would soon be under frontal assault from a cocky band of renegades and dropouts with strange ideas about democratizing computer power. In 1981. the three mostpopularap- plications were word processing (then dominated by WordStar), spreadsheets (VisiCalc), and data- base management CdBASE). Com- puter-based graphics and desktop publishing did not exist. Since then the dominant products have changed, but the basic categories haven't, even though it's been appar- ent for years to researchers and vi- sionaries that text, data, and graphics do not exist in Isolation. There were numerous attempts throughout the decade to integrate the various forms of data; so-called integrated pack- ages (Symphony, Framework, En- able. Smart, Works) stuck a bunch of tools together, tried to give them a common look and feel, and couldn't understand why they failed, often miserably. What was necessary was a para- digm shift, a whole new way of look- ing at the problem, one that did not create artificial analytical distinctions and subsequently wonder why things never came together. This paradigm shift is now under- way, due in part to the success of Windows 3.0, Not because it solves the problem, but because it provides a tangible framework in which to think about it. Another related but distinct factor in this evolution has been the increas- ing success of object-oriented analy- sis, design, and programming. A central feature of all 00 technology is a hierarchical classification scheme that often has a much closer correspondence with reality than pri- or schemes. Whereas the holy grail of integra- tion has consistently eluded the soft- ware community, the hardware folks have shown continuing success. Overall PC size, shape, and cost re- mained relatively constant the pre- vious decade; but during that time, more and more power has been crammed in. Chip density has in- creased by a factor of 1000. New design techniques (e.g., ASIC's) have all but eliminated the use of dis- crete logic, thereby decreasing re- quired space, increasing functional density, decreasing required power, and increasing reliability. Break- throughs are still required in battery power, portable display technologies, and optical read/write media. Suppose you spent $2500 in 1981, 1986. and 1991. What kind of system could you buy? Table 1 provides one comparison. Now take the amount by which each CPU-related category has increased. Bus width is four times greater, standard memory is 64 times greater, and CPU speed is about six times greater; 4x64x6 = 1536. In other words, for the same amount of cash you can now buy 1 536 times the raw comput- ing power you could a decade ago. 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Call (612) 227-5517 SPECIALIZED SECURITY SURVEILLANCE — Audio/vidoe/inlra-red, person- al protection equipment. Public, private, industrial, $9.00 extensive catalog, TRI-TRON OF ATLANTA, 1857G Fox Hollow, Lilbum, GA 30247. 86 PLANS AND KITS ft FASCINATING electronic devices! Dazers! Lasers! FM/AM/phone transmitters! Detectors! Kits/as- sembled! Catalog $2.00, QUANTUM RESEARCH, 16645-113 Avenue, Edmonton, AB. TSM 2X2. SURVEILLANCE transmitter kits tune from 65 to 305 MHz. Mains powered duplex, telephone, room, combination telephone/room. Catalog with Popular Communications, Popular Electronics and Ra- dio-Electronics book reviews of "Electronic Eavesdropping Equipment Design," S2.00. SHEFFIELD ELECTRONICS, 7223 Stony Island Ave,, Chicago, IL 60649-2806. REMOTE CONTROL KEYCBAIN ;: : : : :;!;: C dmjpt-e hi; w/msriiMr arismi \\^f:-:-: :' -a n d +5 Yd t R F. rec e iver;!;! Fully aaaeiTvbfecf liicltitflng plans;: to build your own auto alfttrti Quantity discounts avsl!*bEe: d>0/* rtc Check, Vfw or M r C : *>^^,yO Add S3 shlppJne REMOVE LEAD VOCALS v From Records I CD's Build tut til be under S60 *t»dT lomwM iMd vc^ols from stand jrd itflrw rvcofds. CP"i, tapce or FM broadcuto. Easily eonrwcta to any heme competent tttroo. Ptrlorm Irya wlm The backgrounds. You can b« he lead tirvgor of your favorite band. Detailed Plena. 54 5* Weeder Technologies 14773 Lindsey Rd. ML Or»b, Ohio 45154 > ■■VfSITECT tMC: ■■■■■: (415)531-8425 Box 1*15?, Fremont, Ca, 94539 Fax (415) 531-8442 THE Christmas card (see December 1990 Radio- Electronics or 1992 Electronic Experimenter's Handbook) is a six inch tall Christmas tree drawn with printed circuit traces. Fifty LEDs are activated by sound, powered by batteries or AC adapter. Com- plete kit, including all components and custom frame, $125.00. PC board only, $35.00. ART WORKS, 415 E. Emerson Street, St. Francis, KS 67756. PC boards etched and drilled .70 cents per square inch. Send your requirements to: JM ELEC- TRONICS, Box 150454, Altamonte Springs, FL 32715-0454. Or fax (407) 767-5969. KITS, sound, light, high tech. and unusual. Send lor free catalog. JM ELECTRONICS, Box 150454, Alta- monte Springs, FL 32715-0454. H O B B Y/broadcasti ng 'H AM/C B/s u rvei I lance tran s- mitters, amplifiers, cable TV, science, bugs, other great projects! Catalog $1.00. PAN AXIS, Box 130- F12, Paradise, CA 95967. BUILD our picture only, satellite TV descrambler for most channels. Uses 6 transistors and 4 chips. Most parts from Radio Shack. For educational purposes only, not to be used illegally. Circuit board and plans $30.00 U.S. funds. Circuit board, plans, and parts kit $89.00 U.S. funds. Build a super high economy carburetor, to make eight cylinder engines run on less than one gallon of gasoline per hour. Plans for 5 types $20.00 U.S. funds. Cheque, money order or Visa welcome. Order from VALLEY MICROWAVE, Bear River, Nova Scotia, Canada BOS 1B0. Tel. (902) 467-3577 8 to 4 eastern time. Fax: (902) 467-3937 anytime. PAY TV AND SATELLITE DESCRAMBUHG ALL NEW 19K EDITION ALL MEW H'stpls ih? iT-nuK Alf ncev update en uhl* ,vif el ek and Mtei-itE Turn-cm. bypasses, circuits, chipping, builds., bags, Dcct&c. Liberty Or-c. ECM's. Psla Readers, prafframmintj. and late mere Our &bs >,« amy $15 .95. Olhw (all d I- terwrt) BdiiiOfis 1991. 1969. volume One- [Basics] Si 5.95 each. M0S Handtawfc £9.95. SiklMt systems under $600 $12.95.. Ary 3429.95 or 6/S49.95. Video $23. 95. Scrambling News MonlWy $24.95£m^ MUia HIAtV awpy **jFh mnla reuur wu won fm w m it as WU8ANTB WE CAHW ALL MAJOR BRANDS BEST PRICE BEST THE CONHECnOH FOR MOB£ INFORMATION CALL Oft WRfTE 1-512-260-5031 JtKE&*«o»«* I V I A. tW WW ' tun DEPttt hmm tbwi 7irw REMOVE VCR copy protection, PCB PAL instruc- tions S16.50 w/P&H, LOGICAL CHOICE, Box 1256. Lomila.CA 90717. SATELLITE TV descrambler. Build your own. Easy to follow instructions, parts list, circuit board, wiring diagram. S9.95. ABQ ENTERPRISES, 27081A, Halifax, NS. B3H-4MS. EXOTIC su rve 1 1 la nee kits. E asy to b u i I d , co m p I ete plans/kits for professional transmitters, phone bugs, room monitors and much more, brochure $1.50. SPY SHOP, PO Box 6703, Panama City, FL 32404. 4F % Ferro Fluid Pro-Tech ferro fluid is commonly used on voice coils to substantially Improve frequency response. increase transient and continuous power handling capabilities and reduce second and third order harmonic distortion. It reduces the Q and lowers the impedance peak at resonance without a significant reduction In 5 PL Ferro fluid can effectively increase power handling capability of a driver by 200-300%. Genera] purpose fluid for tweeters and midranges only. iQcc bottle (enough for 75-f CM tweeters). 195 #RM-340-430 $19 Each Light Oak Speaker Cabinet Premium ported speaker cabi- net made of acoustical grade particle board and covered with a light oak vinyl Faminate. P re- cut with an 11 -1/4" hole lor use with most 12" woofers. The baffle board has no tweeter or midrange holes for design flex- faility. The a/4" thick particle board ensures low panel reso- nance. Dimensions: i i's. 15"x 27'. Volume: 2.5 cu ft. Grill and terminal included. Sold Individually. $49- $45 50 Each (2- up) #RM-262-100 12 Gauge Neon Wire The competition in today's auto sound contests Is so lierce that good sound alone is not enough to win. More and more installers are striving 10 make their installation more pleasing to the eye. Parts Express now slocks 1 2 gauge speaker wire in vibrant neon colors. This wire Is the same high quality, made in the U.S. wire you have used belore, but now it has flashy, neon colored insulating jackets. Available in neon pink, neon green, and neon orange. Sold by the foot on or 50 ft. spools. #RM-100-162 (Neon pink) #RM-10Q-166 (Neon orange) #RM-100-170 (Neon green) Tuned Port Tubes These attract Ive. preformed tuned ports altow the back pressure ra- diated Irom the rear of the woofer to reinforce the sound level in from. Made of black plastic. Part « Length Oia, 49* /Ft. if (1-9) (10-up) #RM-26u-32u 2' 1-7/8 - 1.40 .35 *RM-260-321 If 1-7/8 - 1.S0 1.20 #RM-2S0-322 5- T 1.65 1.30 #RM-260-323 r 2-7/8- 140 .95 #RM-260-324 5" 2-7/8" 1.B5 1.50 sRM-260-325 3" 2-7/8" 1.6S 1.30 #RM-26B-327 2-1/2" 3-7(8" 1.85 1.50 KRM-260-32B 5" 3-7/B" 1.95 1.60 Ha mixing for quantity pricing. Famous Maker 3-1/2" Speaker Pair Dual cone 3-1/2" speaker pair for upgrading stock dash speakers. Graphite fib er composite woofer co no provides a smooth extended response at all power levels. The high frequency radiator (whizzer) takes o^er from the woofer at 6,000 Hz and greally extends the response past 20 KHz. Strontium ferrite magnet. 3/4" high temperature voice coil Impedance: 4 ohm. Power handling capability: 25 watts continuous. 70 watts peak. Frequency response: 120- 21,000 Hz. Equipped with dust screen. Made in lhe U.S. by a company with over 40 years experience in the auto sound market. #RM -265-275 $29 95 Pair Subwoofer Input/Output Terminal This recessed terminal panel has Inputs tor right and left channels as wall as outputs lor right and left channels to route to your satellite spe aXers. Greally simplifies subwoofer hook-up. Outside dimensions: 3-7/8" K 5-3/8". #RM-260-308 $3 W (1-9) * Ml ^ P3rtS "15 day money back guarantee * StS-OOrninimum order* If ^^3CDFGSS We accsp1 Mastercard. Visa. Discover, and CO. D. orders. ■ If y^MaSiiS 24 hour shipping- Shipping charge -UPS charr rate + SI. 00 ^M^^^l^^^^ (S3. DO minimum charge) • Hours 8:30 am - 7:00 pm EST. 340 F, First St.. Dayton, Ohio 45402 Monday - Friday ■ 9:00 am - 2:00 pm Saturday. Mail order customers, Local: 1-513-222-0173 please call for shipping estimate on orders exceeding 5 lbs. Foreign FAX: 51 3-222-4G44 destination customers please send S5.00 U.S. funds lor catalog postage CALL TOLL FREE 1-800-338-0531 $3 50 (10-up) FREE CATALOG =# o m ED to ID 87 CIRCLE 56 ON FREE INFORMATION CARD s°* g z O s I LU —1 H 6 Q < DC 88 EASY ORDER 1-800-582-4044 t EASY FAX 1-800-582-1255 J THE ElFCrgQ SOLDERING STATIONS SULObHING/DESOLDERING STATIONS SPECIFICATIONS Power 1 20Vac Heater Voltage 24Vac Heater Power 60 Walt Temp, Range 100"-470°C 200°-878°F Standard Tip 44-510804 ^fei^fr Autotemp 1 S8-3CK Supertemp XY9-60DK 8°s Order # SIA30K/60K Upgrade Those Old Stations For Christmas" Price Description Weight 168-3CK 69.95 60 Watt Soldering Station 2.38 lbs. XY9-60DK 109.95 60 Watt Solde ri ng Statto n ( Digital Readout) 4.6 8 lbs. SIA30K 22.95 30 Watt Mini Pencil Assembly for 1 68-3CK0 Soldering 120V*,:: Desokiffring 30 Watt 60 Walt ■2V:,. 100-450'C 100-470'C ZK-StZ'F 2I2-878"F 44-641010" 44 -5 16604 120V*C 24V»C Order # Price Descript i on Weight 999DA 269.95 30 Watt Desoidering Station 8.82 lbs. 999SD 399.95 60 Watt S oldering/Deso Idering Statio n 17.66 lbs. OIA30 59.95 30 Watt Replacement Desolder Iron Assembly 10.1 oz. D1A60 59.95 60 Watt Re placemen i Desolder Iron Assembly 10 oz. 75-999001 6.95 Replacement Solder Collector 0.9 oz. CORDLESS DRILL KIT RECHARGEABLE REWDRIVER SET 1991 IC MASTER Case Size: 1 1 .25" x 8" x 2.75' 1 l e> NWlii Kit Includes: • Cordless drill - Wall plug-in recharge r • Slotted screwdriver bit • Phillips head screwdriver bit ■ Drill bits: 1/16, 5/64, 3/32, 7/64, 1/8, 9/64, 5/32, 11/64, 3/16, 13/64, 7/32, 15/64. 1/4 Order # Price Description Weight E8385A 39,95 Cordless Drill Set 3.75 lbs. SOLDERLE BOARDS Case Size: 11 25" x 8" Kit Includes: - Cordless screwdriver • Bit holder ■ Socket adapter • Adapter with recharge stand •3 pes. Phillips (#1, #2, #3) • 3 pes. Slotted (3/16". 1/4", 9/32"; • 3 pes. Robertson (8-1 , S-2, S-3) • 5 pes Ton (T-1 0. 1 5. 20. 25, 30) ■ 6 pes MM Hex (2. 2.5, 3. 4, 5. 8) ■ 6 pes. SAE Hex (3/32". IfS". 5/32" . 3/1 6". 7/32", 1/4") ■ 7 pes MM Socket (S, 7. a. 9. 10, 1 1 , 1 2) ■ 7 pes. SAE Socket (3/16".V4",5/16",1 1/32\3/8".7/16\ 1/2") Order # P rice Descrip tion Weight E6367 34.95 Rechargeable Screwdriver Set 3.5 lbs. PRECIS DC POWER SUPPLIES 1 "For The Enthusiast Who Has Everything" 'Convenient -Affordable ■ Easy To Use -Indispensable • 30,000 Different ICs (Including 12,000 new ICs on the market) ■ i.ooo Manufacturers' Data Pages (100% new and updated) -180.000 Pin-lor-Pin Replacement Devices ■Military •Digital] ■ Microprocessor -Interface -Linear -Memory -PLDs -ASICs -MPU Development Systems Order # New Updated 3 Volume Set 91 MASTER Price Description 134.95 1991 IC Master Weig ht 7 lbs. "Don't Forget The Test Bench - How About A Spare Proto Board 'Just Becoz' " < * fe „"„^**' *«< SB3220 no. MOTOROLA DATABOOKS "Need A Power Supply For All Those Xmas Widgets?" #***#* SB2390 SB1660 FEATURES ■Color coo rdi nates for easy recognition ■Insertion wire: 20-29 AWG (0.3 - 0.8 mm) •Over 10,000 insertion cycles *a gf, ■Accepts all standard components ™ ■ P <*<* Price Price Dimensions (in.) Terminal Order # 1-9 10+ LxWxH Points SB200 SB400 SB630 SB830 SB 1360 SB1 660 SB2390 SB 32 20 2.99 4.89 5.45 6.49 2.49 4.39 4.95 5.99 12.49 11.99 17.45 16,95 22.49 21.49 31.49 30.49 6.5x0.37x0.4 3.3x2.2x0.4 300 6.5 x 1.4x0.4 630 6,5x2,2x0.4 630 8.5x3.9x1.2 1,260 8.5x5.1 x1.2 1,260 9.1 x 6.9x1. 2 1,890 9.5 X 8.3 X 1.2 2,520 Complete Line ol DC Power Supplies to Convert 120VAC to 13.8VDC ±0.5Voc. Standard Features Include: -Solid state integrated circuit provides excellent regulation •Output voltage maintained up to 95% of no load value ■High quality filtering for low noise operation -Heavy duty power transformer tor complete line isolation -On/off indicator light and rugged on/oft switch on faceplate ■3 conductor grounded cord on 10 Amp and larger models •Current limiting elee. foldback for auto, overcurrent protection ■2 year warranty Intcrmittant Communications Duty (50% Duty Cycle) ICS* Continuous Order # Price (amps) Duty (amps) Weight RF Device Data - Volumes 1 & 2 This two volume set contains over 2200 pages ol data on RF Power TMOS FETs, RF Power Bipolar Transistors, RF Small Signal Transistors. Tuning and Switching Diodes, and RF Amplifiers. AEso included are drawings, diagrams, dimensions and pin-outs on all packages. Order#DL110 14.95 Weight: 4.25 lbs. Optoelectronics Device Data Over 400 pages on Optoisolators. Emitters, Detectors, Fiber Optic Emitters and Detectors, Opto Assemblies and more. Order#DL118 7.95 Weight: 11b. Linear and Interface ICs Over 1500 pages on Motorola's complete line of Linear and Interface ICs including Operational Amplifiers, Voltage References, Comparators, A-io-D and D-to-A Converters, ete. Also included is a cross reference chapter listing Motorola direct replacements and functional equivalent part numbers for other industry producls. Ord9r#DL123 14.95 .......Weight: 3.25 lbs. PR4.5 32.95 PR7 PR10 PR15 PR25 PR40 PR60 44.95 64.95 B9.95 126.95 179.95 249.95 4.5.. 7.. 10., 15. 25. 40. 60. -5 lbs. ...5 7 lbs. ..7.5 10 lbs. ,..12 13 lbs. ..20 20 lbs. ,,.32 26 lbs. ..48 29 lbs. Telecommunications Device Data Almost 900 pages covering Switching, Integrated Voice Data, Modem, Filler, Data Communication, Basic Phone. Cordless Phone, Transmission and RF Modem Circuits. Order# DL136 11.95 ...Weight: 1.75lbs. MPU/MCU/Pertpheral Data - Volumes 1 & 2 Over 2800 pages on Motorola's Microcontroller and Microprocessor lamilles such as the MCS800, MC6802, MC6821 , MC6845. MC146818. MC6S7U1. MC68705, etc. Order #DL139 16.95 Weight: 4 lbs. CIRCLE 17B ON FREE INFORMATION CARD 'CJtRI&TMSXS CflVTS TOR YOWL £IP& St. fr> *•% ^A^ St B» ^^f Wisfiiiuj You 9i U Merry Christmas! %* E3900 (92 Piece) Case Size: 18"* 14" 1 x 7" ES305 (51 Piece) Case Size: 17.5" x 12.5* x 3.5' E8305- CONTENTS; * Utility componerHs box * 10 fool tape rule ■ Electric lap© ■ 6" long tweezers * 7" brush and scraper * 7" fine point probe ■ 7" si died probe -Digital multimeter ■ Rosin core solder • Desoldering pump - Soldering stand ■ 30 Walt soldering iron wifr. long lite tip - 5.5" stainless steel scissors « Brush (to clean keyboard , monitor, etc.) * 2 piece needle file (round and flat) • 6" adjustable wrench • Heavy-duty utility kniEe * 5-25" bent needle nose pliers ■ 4.5" diagonal cutting pliers * 5,25* flat nose pliers • 5,25" needle nose pliers * 10 piece line color screwdriver set: Slotted- 1/8x3. 3/16x4. 3/16x6, 1/4x1 1/2,1/4x4, 1/4x6; Phillips- 1/8x3 (#0). 3/16x3 (#1). V4x1 1/2 t#2),V4x4 (#3) - 6 piece precision screwdriver set {1/32. 3/64. 5/64. 3/32, 1/6, 9/64) ■ 8 piece hex key wrench set (fottf type) (0.05, 1/16, 5764. 3/32, 7/64. 1/8.9/64,5/32} EB9Q0- CONTENTS: - Brush * Mini flash light * Mini drill ■ Anti-static strap ■ Ulillty knife - Mint vacuum cleaner ■ 3C extractor ■ 30 Watt soldering ]ron ■ Hobby vise ■ Soldering stand * Electric tape - De sol den rig pump ■ 3 prongs holder - Rosin solder core * 5" flat nose pliers * 6" adjustable wrench ■ 5" long nose pjiers * Utility components box * 5' bent nose pliers * 5 piece miniature file set ■ Long nose pliers with cutter ■ 3 piece saldermg aid kit * Stainless tweezers • 11 pleoe screwdfiver set * 4.5" diagonal cutting pliers ■ Electrical test screwdriver - Digital multimeter * Cleaning solution (60 cc) * 5.5" slain less steel scissors * Head cleaning HukJ [18 cc> * 7 piece folding hex key wrench set ■ 9.5" 5-way crimping tool - 5 piece precision screwdriver set: Slotted - .Q9 n x3"„ AQTx4", . 15*j(6"; Phillips - .09"x3" (#0), -19-x4" (#1). .15"x6 H (#1) - 10 piece miniature combination wrench set i,5 ■■32". 3 iG". 1/4' a 7/32", 15/64*, 5/16", 9/32*, 3/8". 1 1/32*, 7/16") Order # Price Description Weight. 119.95 51 Pc. Pro Tool Kit 12 lbs. 199.95 92 Pc. Electricians Tool Kit ....17 lbs. M4B50CR M3800 FEATURES ■ Max. Display: 1999 counts with automatic polarity indication -Max. input Current of AC and DC: 20 A (max. of 15 minutes) * Overrange Indication: "T Figure only on Ihe display » Max. Common Mode Voltage: 500VOC/AC RMS * Reading Rate Time: 2-3 readings per sec (approximate) ■ Temp, tor Guaranteed Accuracy: 23*0 iS^C * Temperature Ranges: Operating D°C to 40 a C, 32*F to 104*F; Storage -10*C to 50°C, 14 Q F to 122°F * Power Supply: One 9V battery (Included) * Size: 35 H W x 6.8"D x 1 -'- >■: ■ Unit Weight {Excluding carrying case): 0.8 lbs. i Indudi-ng 9V battery) * Accessories: Operating manual, 9V battery, test leads, spare fuse and carrying case. M4650CR FEATURES Max. Display: 19999 counts with automatic polarity indication - Max, Input Current of AC and DC: 20A {max. of 15 minutes) * Overrange Indication: "OL H and "Bar graph flashing" figure on display * Max, Common Mode Voltage: 500VocMC RMS * Reading Rate Time: 1-2 readings per sec. (approximate) ■ Temp, for Guaranteed Accuracy: JKPC ±5*C * Temperature Ranges: Operating C C to 40 D C, 32*F to 1Q4°F; Storage -10°C to 50 D C, 14°F to 122 D F * Power Supply! One 9V battery {Included) ■ Size: 3.4*W x 7.4"D x 1.3"H - Unit Weight (Excluding carrying case): 0,8 lbs. (Including 9V battery) • Accessories: Operating manual, 9V battery, test leads, spare fuse and carrying case. RS-232C Cable, Floppy Disk (Option) Order # Price Description Weight EST INSTRUMENT Fieldpiece DMM'sForThe Test Bench Or On The Go M38O0 34.95 3 tffi Digit LCD Multitester.,1 .22 lbs. M465QCR 109.95 4 V2 Digit LCD Multitesler.. 1.50 lbs. RS232C 9.95 RS-232 Interlace 3.5 OZ. SPECIAL FEATURES - Dangerous voltage warning IH523 and HS25): At >2BV. meter beeps £ red LED blinks. Logic Indicator 1HS25): Uprttown arrows m LCD rndicaie logic states Til" (>2£+ -.8V) or ^o" (<6.8+ ..5V). AC coupled. Frequency response 2DM(ti, 25ns mm. pulse width, input impedance i?0K. tOKrl shunted by 100pF Putse rise lima (max) 10 u Sec Pulse rep rale imaxl iMpps. Overvollape protection SQOVOt or nc FMS. Capacitance (HSS3 and HS25) 1 range: 20Ou:F, accuracy 3T.*5. Tested at 3VMOM2. Overload protection to 500VPC or RMS. Aulp-power oft alter 1 hour. GENERAL SPECIFICATIONS - Display hold: Press "MOLD" button, display "locks' reading. Any range, any function. Heavy duty case design of hi-imoact. lire relardant yellow Vale*, fully "O" ring sealed. Meets MILT.28B0O class II type A. Size (nol Including probes): 7.Z>1.9"!<1 0" Weight- IBS grams. Indicators: Continuity (. tlKTrtHMCS Tlffi PLTWJASRH AGREES TO COMPLY WITH AIL STATfi AND FKCBKAL TAWS REOr\K£HNG ntJVATli OWNERS1EF OF CAULS TV iqUITKET. IF YOU AJX UteUM OF THESE LAWS OTECK HUB YOUR LOCAL OFFldAlS. CIRCLE 53 ON FREE INFORMATION CARD INVESTIGATORS, experimenters — Quality new plans. Micro and restricted devices. Free catalog. Self addressed stamped envelope required. KEL- LEY SECURITY, INC. Suite 90, 2531 Sawtelle Blvd., Los Angeles, CA 90064. PCB and schematic CAD. $195.00 IBM EGA CGA Multilayer, rubberband, autovia, NC drill, laser, dot matrix, plotter, library, Gerber, AUTOSCENE, 10565 Bluebird St.. Minneapolis, MN 55433. (612) 757-8584 free demo disk. DIGITAL recorder. Digitally record any audio source with special effects. Microprocessor con- trolled device. Detailed plans. $9.75: T. ZURAW, Box 341. Dearborn Hts, Ml 43127. CABLE TV DESCRAMBLERS ! CABLE KINGDOM! *JER0LD* *OAK* *HAMLIN* *ZENITH* *PIONEER* *SCIENTIFIC ATLANTA* IN STOCK 6 MONTH WARRANTY! WE SHIP COD! ABSOLTLEY LOWEST ga WHOLESALE/RETAIL PRICES! DESIGN circuits on your I.B.M. or Commodore P.C. Power supplies, amplifiers, oscillators, and circuit board layouts. Eleven programs priced from S19.95 to $24.95 each. Catalog $2.00, Order today! WEASELGRAPHICS, PO Box 647 Dept. Weasel Sun Ciiy, CA 92536-0647. Mastercard and Visa orders 1 (800)356-8113. ANTIQUE RADIO CLASSIFIED Free Sample! Antique Radio's Largest Circulation Monthly. Articles. Ads & Classifieds. 6-Month Trial: $15. 1-Yr: $27 ($40-1 St Class). A.R.C., P.O. Box 802-L9, Carlisle, MA 01741 s p HI o Q 2 J .P . VIDEO 1470 OLD COUNTRY RD SUITE 315 PLAINVIEW, NY 11803 NO N.Y. SALES CALL NOW! 1 (800) 950-9145 PRINTED circuit art work. Low cost, for tree infor- mation write NEGRON ENGINEERING, 159 Gar- field Place. Brooklyn. NY 11215. Fax or call (718) 768-4028. CABLE DESCRAMBLERS OAK M35B COMBO $39.95 Jerrold, Zenith, Hamlin, Sci. Atlanta, Pioneer & MORE! OUR PRICES ARE BELOW WHOLESALE! CABLE+PLU8 14417 Chase a. #481-A Panorama City. CA 91402 1-800-822-9965 • Other Info. 1-818-785-4500 NO CALIF. SALES - DEALERS WANTED THIS IS AN ALL BOLDFACE AD. If you want your entire ad in boldface the cost is $3.65 per word. BUY BONDS IMPROVE YOUR DESIGNS Save power, board space, and fabrication time. The PAL Compiler program lets you combine the functions of several ICs into a single PAL, GAL, or PEEL device. Use either truth-table or logic equations as input. Stan- dard J E DEC file is output Quick logic term minimization is included. $69,95 + shipping, ■'handling/tax Call to order, or (or free information. (916)674-1626 TIMELY SOFTWARE, INC. 1747 Uve Oak Blvd. #J-210, Yuba City, CA 95991 FREE IBM SOFTWARE CATALOGS TRY programs before buying. Your name mailed. 12 shareware dealers $1 .00, 50 dealers $4.00, Deal- er list $1.00 Dealers, your offers this list, $25.00 month. G DUDEK, Box 58, Poolesville, MD 20837. SATELLITE TV FREE catalog — Lowest prices worldwide. Save 40 — 60%. Systems, upgrades, parts, all major brands factory fresh and warrantied. SKY VISION, 1012 Frontier, Fergus Falls, MN 56537. 1 (800) 334-6455. SATELLITE TV — Do it yourself — systems. Up- grades. Parts. Major brands discounted 40% — 60%. Well beat everyone's price. L.J.H. INC., call Larry (609) 596-0656. CABLE TV Secrets — the outlaw publication the cable companies tried to ban. HBO, Movie Channel, Showtime, descramblers. converters, etc. Sup- pliers list included. $9.95. CABLE FACTS, Box 711- R, PAtaskala, OH 43062. SATELLITE TV and cabie descrambling secrets: Surveillance and counter-surveillance; send stamp for free catalog. COMMUNICATIONS ENGINEER- ING, 76 Boulevard. Hudson Falls, NY 12839. SECRET cable descrambler. Build your own de- scrambler for less than $11 .00. in seven easy steps. Radio Shack parts list included. Also free descram- bling methods that cost nothing to try! Send $10,00 to: LOUIE WHITE, 2 Marlin, Baytown, TX 77520. BEST BY MAIL Rates: Write National, Box S, Sarasota. FL 34230 OF INTEREST TO ALL VCR REPAIR-TECHNICIANS' SECRETS REVEALED. Do it yourself, literally save hundreds. Complete easy to follow instructions. Includes 800 numbers of all major manufacturers for ordering parts direct. Simple Schematics/Directions. More. 114.95 to: ACME VCR REPAIR, 2104 Renwick Lane, Antloch, CA 94509. UPDATING YOUR RESUME? For tips that work send S5.00: Franc hards, Boa 704. Aberde en, WA 98520. GLOW tN THE Dark Door Knob Covers, Four S9.95. Shiny Tim. Post Office Box 92972, Lakeland, FL 33364, MONEYMAK1NG OPPORTUNITIES WE PAY UP to $300.00 weekly Woodburning Picture Frames. Everything supplied. No experience or selling. Bay Frame, PO Box 15Sa-(RE), Jackson, TN 36302. HOTTEST MONEYMAKING OPPORTUNITIES Available Send $1.00: Farrells, 2108 Edgewood, Waukegan. IL 60087. ____ EXCELLENT PAY1 HOMEWORKERS Needed! Over 400 Companies need homeworkers/drstributors NOW! Call for amazing r eco rded message 213-519-4192 Ext.(RE). SSI HOMEWORKING! SASE Brings FREE details: CMKT, Box 40444-(RE), Raleigh. NC 27629. CABLE TV DESCRAMBLER LIQUIDATION! FREE CATALOG! Hamlin Combos $44, Oak M35B S60 (mill. 5), etc. WEST COAST ELECTRONICS For Information: 818-709-1758 Catalogs & Orders: 800-628-9656 90 / ELECTECH j CABLE T.V. DESCRAMBLERS • All quality brand names • • All fully guaranteed • All the time • Knowledgeable Sales Service Department FOR FREE CATALOG 800-253-0099 BUSINESS OPPORTUNITIES YOUR own radio station! Licensed'unlicensed AM, FM, TV, cable. Information $1.00. BROADCAST- ING, Box 130-F12, Paradise, CA 95967. LET the government finance your small business. Grants/loans to $500,000. Free recorded message: (707) 449-6600. (KS1), MONEYMAKERS! Easy! One man CRT rebuilding machinery. S6.900.00 rebuilt. $15,900.00 new. CRT, 1909 Louise. Crystalake. IL 60014. (815) 459-0666. Fax (615) 477-7013. RECOVER pure gold from scrap circuit boards, electronic parts. Easy methods. Send $5.00, RECY- CLING, Box11216PE. Reno, NV 89510-1216. MAKE $75,000 to $250,000 yearly or more fixing IBM color monitors (and most brands). No invest- ment. Start doing it from your home. (A telephone required.) Information, USA. Canada $1.00 cash. US funds, other countries $8.00 RANDALL DIS- PLAY, Box 2168-R, Van Nuys. CA 91404 USA. Fax (818) 990-7803. EASY work! Excellent pay! Assemble products at home. Call loll free 1 (800) 467-5S66 Ext. 5192. MAKE $$$! Become an American electronics deal- er! Profit opportunities since 1965. Call SCOTT PRUETT, 1 (800) 872-1373. HOME assembly work available! Guaranteed easy money! Free details! HOMEWORK-R, Box 520, Danville, NH 03819. ' FULL- OR PART-TIME JOB/BUSINESS : Learn VCR repair! Professional-level home study program. Master tf^ easy- to- 1 earn, high-profit I repairs without investing 111 in costly high-tech instru- ments. Send or call today. Free career kit: 800-223-4542 Name Address . City . State The School of VCR Repair, Dept. VP342 , 2245 Perimeter Park. Atlanta, GA 30341 mm ^ mm ■■ ^ bv mm wmt tmt h> mm ■■» mm mi RECESSION?Thrivinq fully equipped audio/video repair shop. $130K f this year! Proven 40% f gross last three years. $70,000.00 cash. AUDIOTECH, 256-B North Highway 101, Encinitas, CA 92024. Fax (619) 944-0345, Phone (619) 944-9048. ELECTRONIC ASSEMBLY BUSINESS Start home, spare nme. Investment knowledge or experience unnecessary. BIG DEMAND assem- bling electronic devices. Sales handled by profes- sionals. Unusual business opportunity. FREE: Complete illustrated literature BARTA RE,Oiortil Pine' Uitci A ?900 3*0" 1Y-45 »S:ERB*i f 0is3 071 *JDt*1 Resnic; S.nci* Vd CaNroi | U 3B» TA-47T, [A :QWVl rA-lMMBi U 0D 022 AlasHtwtiK Dual Vol Control |1 A 3^A TA-SOS ft. ?XK\ 2? 05 SJW30 12EWi l!5WADDCEl«™iii-Fi4Pie.MwiAmp ii 7550 £9 05 TA-MHHK2 1 20W ♦ 1 2QW Lmv Tmt Prc-M am Stum fortti Amp ii « 52 : * S3? 3tW . K-3W Ml-* DC SUrir? Mjm Pcwar Jimp a a 45 &* 55 ^ FA iCOOA lOOWDymmtc Ciih W Hjn PwEr MoflflAmD AA SO M S500 t a- 1550 ioqwx?cim r A r rXii««*Ti-w*flAnrJ aaa T3ro »ai TA-2300 OCFMSuflWOBS'A'OCPre-AnK AAA A7 75 5B24 i A350Q UC- Prr Amp w.10 Hand Qnpfoc eq tJ . r fr * fi 00 rA?K» BIFET IC PTrAmpwfl wly IcmtcomrcH AA 4S 90 63£7 REGULATORS T tV3S5A 5-I5V 5A FltguXH! CC Pcvur Suppl na =i$e 4 i 'on™ !■ A i :b 65 4 2: ,'t, rfl-155fl 5-35V 3A FltflitlilHS DC Pimir SurB' .' i r : asiin^irmptA 15 65 2l ?t Tfl'KB 4'5WMB*gu ! illiBllKPiT*erS'JE0tirinan,H t .irrmer A a '5 ?5 2idt ■fTAL CAMETS WTTH MJlMMM PM& MODEL H-iW J CT MATCHING PMX LG-1273 3 1 12* J' TA-2BM TA-377A TA 22D0 SZ3S5 LC-lfiM r Iff ff IA-323A. TA-3J7A. U.22tyi 21 » LG-1974 4' 19" 1 1' ■■■ 1AB02 TA 15ffl3.Tfr-(20SM.2 TA^SM HK2' TA ICOO* W » LG-1925 5' 1ST T1^ 1A-477 TA-flOO ^<2. Tft-1 MQ. **■ 1 0WA 1A 3&X M » LG-I9B3 JWtBT £ 1A iHA 'K2WB TA-22O0 lA-lMHK? TAi&M jaWHdKi-riPoRtiMnflDAtnp AAA £5 M 11050 EM-333 An*cjV^« Surwmd Swwl fiocnsw aaa* SSOO . : iw SMH66 frnvmc H*w Hrtucuon A »CKI 34 H SH-£aS Unirtiul AudirWirSM KARAOKE «u*i. PftAmp * l»Q0 nM^TJlMtFORMBtt P4OTAI METERS AW CDUKTER WT USEMI, WDDF.L DESCfllPTIDN HATCHIND PRICE Mi 31V k ? EA lo 30V ■' 2 6A TA 130 HK2 TA-8S2. T.A-1 050*. TA 1550 £2150 M? ■•: i ■ ' H TR-503 TA 323A TA^*M TA 350. TA-377A 23.00 M3 *r,Vw£,* TA-477 3B00 DOA ZAVtJEA TA'120MK2 2300 DOS ?SViI2A TH-3SSB 1700 OK ISVxZM Tnr35SA 1750 D07 ':■,.,■-.'. TA-3C00 45 00 &M J! 3-x Muini-Fijncrjonw Lid D P ** I WABS ptistic cjce i A A '■ 1 1 ■. I S i j >:- 5M-IG <-*Hi-ft«i«nB?MAAA .3100 «1« SU^IU JMHhhtMiDnO'PM Iw.'A&SoliitCUK^A* 41 » »50 SH-J9 3^ HuHi-FimctK)nil LOO H P [w,He« F u nct>on r 10O:1 random random random random random >500;1 random random >500:1 random 1750v-110v 1000vi100« 1C50v-100v 1000v^100v ICOOv-IOOv 130Uy^100v 1300v-100v 1300v-100v 1250V -1Mv 1900v -lOOv 1900v-100v 1750v- lOOv 6.5 mA 3.5 mA 2.8 mA 3.5 mA 3.5 mA 3.5 mA 5.0 mA 5.0 mA 6.5 mA 6.5 mA 6.5 mA 6.5 mA FIRING VOLT. £ 8kV < 7kV < BkV £ 7kV < 7kV £ 7kV < 7kV £ 7kV < 7kV £ 3kV < 8NV £ SkV MIN. SERIES RES. 81k (1 68k n 82k fl 68k (1 63k (1 aik n 68k n 68k fl 63k a 81k n 81k n eik n SIZE DXL (IN MM) 37x350 25 X 146 22.5x11 25 x 150 25 x 150 20 X 210 30x255 30x255 30x255 37 x 350 37x350 37x350 WT. (GM.) 2GO 70 8 60 70 70 70 140 140 140 200 200 200 BRH CL. Ilia Ilia I lib nifc lllb lllb PRICE 1-9 799.99 529.99 134.99 144.99 159.99 249.99 204.99 209.99 359.99 369.99 399.99 479.99 749.99 479.99 124.99 134.99 144.99 229.99 191.99 194.99 334.99 344.99 364.99 444.99 Laser Pointer • Output: 3.5 mW • Wavelength: 670NM ■ Power Supply: 2xAAA Batteries (included) ■ Beam: Apprax. 3" @ 100 yards Quantity Discounts Available STOCK # PRICE LS POINT $199.99 Power Supply & ■ Input: 115/23QV ■ Output: +5v @ 3.75A +12v@1.5A -12v@.4A ■ Size: 7" L x 5V," W x SW H STOCK # PS1003 PRICE $19.99 Collimator Pen ■ Output: 2.5 mW (max.) ■ Current: 90-150 mA • Op. Volt.: 2.2-2.5V • Wavelength: B20NM . Data Sheet inc. STOCK # SB1052 PRICE $39.99 Disc Drive & Computer Cleaning Kit Nol just a drive oleaner-but a complete computer cleaning kit. Includes swabs. head cleaning fluid, anti-static cleaner. screen wipes and cleaning diskette. STOCK* PRICE SB1099 3Vj" Kit $6.99 SB1100 5VT Kit $6.99 Disc Drive Head- Cleaning Kit Anti-Static Screen Wipes Robotic Arm Kit Avoider Robot Kit Includes cleaning fluid and head-cleaning diskette STOCK* PRICE SB1105 W Drive Kit $1.99 SB 1106 5 Vi" Drive Kit $1.99 For static-sensitive applications. Dispenser packs, mdividually wrapped. STOCK # PRICE SB1104 Dispenser pack $1.99 of 25 wipes SB1 1 07 Dispenser pack 54.99 of 1 00 wipes Rotiols were once confined to science lichon movies Today, whclher they're periO/tiTiing dangerous tasks or putting together complex products, robotics are. hndmg Ineir way into mof e and more industries. The Robouc Arm Kit i J an educational mI thstt teaches, basic rotjoiic arm Fundamentals as well as testing your Qrwn motor skills Command it to perform simpld Ms»: : ♦ STOCK # Y01 PRICE $49.99 An intelligent robot that Knows how lo avoid hitting walls. This robot emlls an intra-red beam which detects an obstacle in Iron! and then automatically turns left and continues on STOCK # MV912 PRICE $49.99 ORDER LINE — (800) 824-3432 INTERNATIONAL ORDERS — (818) 341-8833 FAX ORDERS — (818) 998-7975 TECHNICAL SUPPORT — (818) 341-8833 CIRCLE 181 ON FREE INFORMATION CARD • 15.00 MINIMUM ORDER • UPS BLUE, RED S FEDERAL EXPRESS SHIPPING AVAILABLE • OPEN MON-FRI 9:00 AM - 6:00 PM, SAT 10;M AM - 3:00 PM PDT • CA RESIDENTS ADD I* SALES TAX • CALL FOR QUANTITY DISCOUNTS • CALL FOR FREE CATALOG (FOR 1ST CLASS DELIVERY OR CATALOGS DELIVERED OUTSIDE THE U.S. — SEND S2.00) • WE CARRY A COMPLETE LINE OF ELECTRONIC COMPONENTS •NO SHIPPING CHARGES ON PRE-PAID ORDERS DELIVERED IN THE CONTINENTAL U.S. O m o m S 5 m 33 -J. $ 95 AMAZING SCIENTIFIC & ELECTRONIC PRODUCTS LASERS 4NC SCIENTIFIC DEVICES ¥RL2tt am* HIS Bid Li«> Dludt Syttim Hfl $159.51! U.IS1K Lsier Senm- Bduiki" ' islam! 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Pulsed Drilling User Plans S2D.rjn LGU40 1 lo 2mm HeNt Vis Btn Ljsh Gnu »i«mlll(d $199.00 LI $1 Laser Lite Show - 3 Methods Plini $20.00 5D5K See In lilt Dirt Kit $299.50 EML1K Electromagnetic Coll Gun Kit $09.50 MCP1 HI Velocilj Coil Gun Plant _ $15.00 LEVI Levitating Device Plans $10.00 EH1 Electronic Hypnmisrr Techniques Plans $10.00 HIGH VOLTAGE AND PLASMA DISPLAY DEVICES HVM7K 75.000 Volt DC Variable Output Lab Source Kit SIM 56 IOG3K Ion R ay Gun K II oroj ec t a ner gy wi Ih nul were I $69.50 NIG9K 12V,'115 VAC Hi Qui Meg Ion Generator Kit $34.50 EMA1K Teleimelrc Enltancer/Eteclric Man Assembled $99.50 LG5K Lightning Dlipls) Globe KH (54.51] BTC1K Worlds SrnalleslTesI j Coll Kit 549.50 BTC3K 250KV Table Ton Tesla Coil Kit S249.50 BIOS 1.5 Million Vails Tesla Coil Plant $20.00 JL3 Jacobs Ladder -3 Models Plans $15 W CHA1 Anti Gravity Generator Plans $10 00 PFS20 Plasma Fire Saber Assonmuid $59,511 DPL2C Dancing Plasma Ic Music ano Sounds Assembled $79.50 SECURITY AND oROTtCTTDN DEVICES ITM10 100,000 Voll IMimiOntor -JO to 20' Assembled $129.50 IPG70 Invi si ble P a i n Field Bl as: Wave G en Assembled $74.50 PSP4>! Phasor Sonic Blast Wave Pistol Kit $59.50 LIST10 InlinilyXmir, Listen in Via PhDne Assembled $199.50 T/YTCO AuiomaEic Tel Recording Devicp Assembled $24.50 VWPM7K 3 Mi. FH Auto Tel Transmitter Kit $49.50 FMV1K 3 Ml. Ffrl Voice Transmitter Kit 539.50 HDD1K HomingTTracVIng Beeper Transmitter Kit $49,541 EUI OnOEHINC PROCEDURE TOLL FREE '.-S0O-221-17II5 or 24 HRS OH 1-(03-S73-4739 or FAX IT TO 1-503 6J2-540S VIS* MO. CHECK MO IN [IE FUNDS INCLUDE 10% SHIPPING. ORDERS S 100.00 A OP OKLT ADO Sit go SATALOP y gg gR FREE WITH ORDER. INFORMATION UNLIMITED P.O. BOX 716. OEPT. R3. AMHERST. NH 03031 q Lit _J UJ 6 o < CABLE TV DESCRAMBLERS THE MOST ADVANCtD TECHNOLOGY IN CABLE EQUIPMENT: • RASE BAND • JERROLD • PIONEER • TDCOM ■ HAMLIN • ZENITH • SCIENTIFIC ATLANTA • OAK For GSUt of this world prices call WORLDWIDE CABLE 1 800-772-3233 FREE CATALOG AVAILABLE 7491 C-5 N. FEDERAL HWY.. SLhTE 142 BOCA RATON. FL 33487 MC / COD / VISA NO RXMM SAiBS CIRCLE 194 ON FREf INFORMATION CARD I * * * * PRESENTIM" « * * * CABLE TV T ■tr * M * * STARRING * * * * * JERROLD, HAMUN. OAK AND OTHER FAJMOLiS MAJV' JFALVOHEfrS • Fit JEST WARRANTV PROGRAM AVAILABLE • LOWEST RETAIL I viHOLESAl L" rnrcrs IN U.5 > ORDERS SHIPPED FROM STCtK WITHIN 24 HR5. ALL MAJOR CREDIT CARDS ACCEPTED FOR FREE CATALOG ONLY 1-800-345-8927 FOR ALL INFORMATION 1 -8 1 8- 7 09-99 3 7y PACIFIC CABLE CO.. INC. 7325' ? Reseda Blvd., Dept. 2109 Reseda. CA 91335 EDUCATION & INSTRUCTION F.C.C. Commercial General Radiotelephone license. Electronics home study. Fast, inexpensive! "Free" details. COMMAND, D-176, Box 2824. San Francisco. CA 94126. PRACTICE troubleshooting on your IBM PC. 32 circuits including diodes, transistors, FETs and op amps. Hundreds ot troubles. Visa, MC $49.9E. 3.5" or 5.25." Demo $5 00. MALVINO \nr , £^o Polaris Ave., Ml. View, CA 94043. WMimmMA DESCMMBLEKS WHOLESALE TO ALL EXAMPLE OAK RTC-56 99.00 TOCOM 5503 225.00 SYL-404O-DIC 49.00 TRI-BI. . SA3B. .59.00 NO CATALOG-GRBAT PRICES 80H22-3799 BE a recording engineer; T ain at '.ome for high paying — exciting careers. Free information. AU- DIO INSTITUTE, 2258-A Union St., Suite K. San Francisco, CA 94123. COMPLETE course in electronic engineering Eight 'Volumes. Includes all necessary math and physics, f ree brochure. BANNER TECHNICAL BOOKS, 1203 Grant Avenue, Rockford, IL 61103- TELEPHONE home study course. Professional cer- tification ASSOCIATION OF CERTIFIED TELE- PHONE TECHNICIANS, Route 3 Box 98. Ellington, MO 63P38. CABLE TV DESCRAMBLERS * CONVERTERS* and ACCESSORIES. PANASONIC, JERROLD, OAK, PIONEER, SCIENTIFIC ATLANTA AND MORE. LOWEST PRICES. FREE CATALOG. 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REPUBLIC CABLE PRODUCTS, INC E=j 4080 Paradise Rd. #15, Dept re mi rn Cf3 Las Vegas, NV 89109 ESI For all other information (702) 362-9026 This publication is available in microform from University Microfilms International. □ PteasE send information about these EiUetK Name . Company/Institution Address. Cily Stale Phone I Zip„ Call toll-free B0O-52 1 -30-.4. Or mail inquiry to; University Microfilms International. 300 North ZeebRoad, Ann Arbor. Ml 46106. 48 „our ELENCO & HITACHI PRODUCTS M ™ SHIPPING AT DISCOUNT PPIOFS 1-800-292-7711 Hitachi RSO Series (Portable Real-time Digital Storage Oscilloscopes) VC-6023 - 20MHz. 20MS/S VC-6024 - 50MHz, 20MS/S YC-c.025 - 50MHz, 20MSrS VC-6045 - 1 00MHz. 40MS/S VC-6145- 100MHz, 100MS/s_ RSO's from Hitachi feature roll mode, memory, smoothing, interpolation, pretriggerinn measurements. These scopes enable more accurate, simplier observation of complex waveforms, in addition to such functions as harccopy via a plotter interlace and waveform transfer via the RS-232G interface. Enjoy the comfort of analog and the power fo digital. 25MHz Elenco Oscilloscope £1,695 $1,995 $2,195 $2,995 $4,495 averaging, save cursor SPECIAL BUY V-212- 20MHz Scope $425 Hitachi Portable Scopes DC !o 50MHz, 2-Channel, DC offset func- tion, Alternate magnifier function V-525 - CRT Readout, Cursor Meas. S995 ■ Delayed Sweep S97S ■ Basic Model. $875 ■ 40MHz _ $775 £695 $625 HITACHI COMPACT SERIES SCOPES This senes provides many new functions such as CRT Readout, Cursor measure merits (V-i 085/1 065 A*65A), Fre- quency Ctr, (V-10B5), Sweeptime Autoranging, Detayed sweep and Tripper Lock using a S-mch CRT.You don'i teal the compactness in terms ol performance and operation. V-523 V-522 V-422 V-223 V-222 ■ 20MHz delayed sweep. 20MHz deluxe V-660 - 60MHz, Dual Trace V-665A - 60MHz, DT, w/cursor _ V-1060 - 100MHz, Dual Trace V-1 065A - 1 00MHz, DT, w/cursor , V-1085 - 100MHz, QT, w/cursor _ V-1100A- 100MHz, Quad Trace _ V-1150- 150MHz, Quad Trace _ $1,149 $1,345 $1 ,395 $1 ,649 $1 ,995 $2,195 $2,695 $349 ,i S-1325 » Dual Trace • 1mV Sensitivity •e'CRT • X-Y Operation • TV Sync • (2) IxTlOx Probes included »'; Ft! PRICE BREAKTHRU 20MHz Digital Storage O*clllo*cope • AnaiogrDigilei Scope • 2K word per channel memory DS203 • 1 0MS/s sampling rate $795 • State-ot-an technology • Includes probes Elenco 40MHz Dual Trace ■Good to J 4 g 5 50MHz ; r - ■ < . '-' i S-134Q High luminance 6" CRT V . 1mV Sensitivity wF* 1 0KV Acceleration Voltage * i; #i ■ | • 17ns Rise Time • X-Y Operation • Includes (2) 1x, 10x Probes All scopes include probes, schematics, operators manual and 3 year (2 yrs for Elenco scopes) world wide warranty on parts & labor. Many accessories available for all Hitachi scope5.CallorwritelorcompletespecificafiorisonitieseandmanyothBrfineosdlloscope$. }x, I0xScopePrObes:P-l 65M Hz $ 1 9.95 , P - 2 1 0QM Hz $26.95 B + K TEST EQUIPMENT Ail Models Available Call for special price Digital Capacitance Meter flSffl CM ' 1550B $58.95 9 Ranges ,1p]-20,000uld 3% basic accy. Zero control * Case Big r Display Digital LCR Meter — - LC-1801 $125 ■Vlf Measures: Coils tuH-2u0H Caps .1pl-200ul Hes .U1-20M ■ - Multimeter with _DQ0'J Capacitance & Transistor Tester $55 CM-1500S Reads Volts, Ohms Current. Capacitors, Transistors and Oiodes ,'' with case t,Z&* ' Big 1" Display FLUKE MULTIMETERS All Models Available Fluke 70-II $65 Fluke 77-II, $145 Fluke 79-II $169 Fluke 87 $269 Call far special price Quad Power Supply XP-580 ,$59.95 2-20V @ 2A 12V @ 1A SV@3A -5V @ ,5A Fully regulated and shon circuit protected Triple Power Supply XP-620 Assembled $69 Kit $45 2 lo 15V @ 1A. -2I0-15V@1A (or4lo3W@1A) and 5V @ 3A All the desired lealuies for doing experiments. Features short circuit protection, all supplies I «• AM/FM Transistor Radio Kit with Training Course Model AM/FM 108 $26.95 14 Transistors * 5 Oiodes Makes a great school project True RMS 4 tffl Digit Multimeter M-7000 135 .05% DC Accuracy .1% Resistance wild Freq, Counter and Deluxe Case $1: GF-8016 Function Generator with Freq. Counter $249 " Sine. Square, Tnangle Pulse. Ramp. .2 lo 2MHz Freq Counter ,1 - 10MHz ImVEx! operation |GF-e01S without Freq. Meter $179 Function Generator Blox #9500 $28.95 *¥;* Provides sine, triangle, square wave from 1 Hz to 1 MHz AM or FM capability Learn to Build and Program Computers with this Kit Includes: All Parts, Assembly and Lesson Manual Model MM-6000 Wide Band Signal Generators $129.00 Starting from scratch you build a complete system. Our Micro-Master trainer teaches you m writs into RAMs, ROMs and run a 6095 microprocessor, which uses similar machine language as IBM p C WE WILL NOT BE UNDERSOLD! UPS Shipping; 48 States 5% ($3 Mir> StO Max) Shipping IL Res., 7.57,. Tax FAX: 708-620-0085 SG-9000 S129 RF Freq 10OK-45OMHz AM Modula- tion of IKHz Variable RF output SG-9500 I Amp • 3DVAC Cenler lapped @ 15VAC @ 1 Amp Analog - Section ■ Function Generator Sine, Triangular, Square wave forms • Frequency adjustable in five ranges from 1 to tooKHz • Fine frequency adjust ■ Ampiiiude adjust . DC ofls at • Modulation FM AM Digital - Section . Eight data seiches • Two no bounce logic switches • Eight LED readouts TTL buffered . Clock frequency t to tOOKHz » Clock amplitude 5VPP square wave Breadboards ■ 2 breadboards, each contain: 840 tie points (total 1 .680) C & S SALES INC. 1245 Rosewood. Deer-field. IL 60015 1X011 1 392-771 1 1 70S I 54 1 -(17 10 CIRCLE 109 ON FREE INFORMATION CARD ; • • [ *HtwCord] 15 Day Money Back Guarantee 2 Year Warranty Prices Subject to Change WRITE FOR FREE CATALOG TEST FOR LESS WITH FORDHAM Now Only £g now or Rugged & Reliable cacrrss ■8 Functions •57 Ranges scope Hand Held Digital Multimeters Model DVM-638 now only w •11 Functions *58 Ranges •Continuity Beeper •Overload Protection Optional Carrying Case CA-92 $9.95 NEV\fl SPECIALTIES Digital Multimeter •3W Digit LCD *10MS Input Impedance •Full Overload proteaion 'Auto Ranging AODC Voltage •Diode & Continuity Checks W^ Current Resistance With Au dible Ala rm ' Aceu racy 0.5% Optiona 'Carrying Cast CA-92 $9.9i SCOPE 314 sign lcr Meter ideal for field applications! •Light weight -Portable -Hand Held Optional Carrying Case CA-92 $9.95 Model 735. A H Aftr Our Price »49 9 5 SULCD Meter Gp SCOPE 3 1 /2 •0.5% Accuracy • DOAC Voltage, DC Current • Diode S Battery Test 'Overload Protection DC 500V, AC 550V Ohms 250V DOAC Model DVM-630 SALE $3250 wfeli ■ W ■ Reg. 550.00 Optional Deluxe Carrying Case CC-30 $4.50 Sweep Function Generator Sale! now «° Reg $313.95 Model FG-801 ■Selectable Wave S TTL Pulse • 7 Frea Ranges iQ2Hzro2MHzJ •Sweep Ratio 1001 SCOPE Analog Lab Sale! now W Reg S225.00 Model sc-6000 •5 Fret} Ranges •Variable Positive Power ■Potentiometer Proto-Board station Special! w Model SC-9000A •3 Wire AC Line Input •Function Generator •Triple Power Suoplv •8 Logic LED's Feature Packed! HITACHI Oscilloscope NW.'BPW Reg S61500 Model V-212 Dual Trace •DC to 20 MHz. 1mVMv •6" Rectangular Screen PROBES INCLUDED' hitachi Dual Trace Oscilloscope NOW $ 598 00 Best value Model V-355 • 19 Calibrated Sweeps . PT -AutO FOCUS PROBES INCLUDED! I c i 1 ... n - 9 Fordham 260 Motor Parkway, Hauppauge, New York 11788 ASK FOR YOUR FREE CATALOG JH 800495-4848 e> Fandham 1991 Offers expire De- Money orders, checks accepted CQD's require 25% deposit Service & Shipping Charge Schedule Continental U.S.A. FOR ORDERS ADO FOR ORDERS ADD S0-25 S4.50 i $501-750 $1600 $26-50 $51-100 S101 200 $201-300 $301-400 8401-500 S600 $750 S900 SIQOO $12.00 $14.00 i $751-1,000 $1800 Sl.001-1.250 $20.00 S1.251-1.500 $2200 51501-2,000 S2750 52.001 and up $35.00