H*m|S M HI-TECH CONSUMER'S nillllll GUIDE TO BATTERIES I ■ ■ |jj ICG trai i i MARCH 1990 ECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE WILD THIS AB0RAT0F OWER UPPLY wo fully floating varia, 0-volt, 5-ampere applies and one fixed i-volt, 3-ampere enchtop needs UILD AN ION IETER ieep track of tin evels of negative ind positive ions in /our environment , ■■ ■ ' :■ , [ ^^^J Mm lA \i 5? S | HAMf»l' j Up ^B li JDIO AMPLIFIER COOKBOOK zens of practical IC audio power mplifier designs u can try today! BUILD DIO LIMITER Eliminate distortion caused by /erdriving or underdriving audio amplifiers mputerDicest uild a keyless entry system based n the 68705 microcontroller 71896 l( 48783' $2.50 U.S. $2.95 CAN GERNSBACK FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT FLUKI PHILIPS Great Choice. More professionals in more industries make Fluke their first choice in multimeters. Fluke DMMs. Reliable. Accurate. Powerful. Tough. Versatile. Easy to use and simple to operate. Backed by the longest, most comprehensive warranty in the business. Mari e in the U.S.A. In short, Fluke makes meters you can bet your reputation on. More choice. No matter what the job, there's a Fluke to handle it. There's the new 80 Series— the most powerful, most complete test and measurement system available in a handheld package. The popular 70 Series— simply put, the most requested DMM in the world, with nearly 2 million units in service since 1984. And the Fluke 21 and 23-70 Series simplicity in high-visibility yellow. The Fluke 25 and 27— the most rugged meters ever built, totally sealed against water, dust and other contaminants. And the precise 8060 Series— with the versatility of a test lab, the accuracy of a bench instrument, and the convenience of a handheld. Smart choice. Compare Fluke DMMs with any other handheld. No one else gives you as much meter for your money. And no other meter costs less to own. CIRCLE 121 ON FREE INFORMATION CARD Your choice. For the name of your nearest Fluke distributor, call toll-free 1-800-44-FLUKE, ext. 33. And make a great choice. John f lake Mlg. Co . Inc P Boi C9090 WIS 250C Everett. WA 95206 U.S.-1206J35&-54M) Canada: (416) 690-7600. Otter Countries- 1206) 3585500 ' I9B9 John Flute Mlg. Co.. toe All rights reserved U No, 049I-F70 FROM THE WORLD LEADER IN DIGITAL MULTIMETERS March 1990 31 UNIVERSAL LABORATORY POWER SUPPLY A flexible, high performance supply for your workbench. Re in hard Metz 35 ION METER Now you can keep track of negative and positive ions in your environment. Peter A. Lovelock 39 AUDIO VOLUME LIMITER Improve the performance of low-cost audio amps. Lowell D. Johnson 42 ALL ABOUT BATTERIES How to select the best power source for your equipment. ..or your next project! Josef Bernard 71 BUILD A DIGITAL KEYLESS ENTRY SYSTEM Use the 68705 microcontroller to improve your security. Steven Avritch 52 WORKING WITH AUDIO POWER OP-AMP IC's A circuit cookbook with scores of practical circuits. Ray Marston MMM2M 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 18 EQUIPMENT REPORTS Jameco Electronics Wishmaker II Prototyping System Becknnan Industrial FG3A 2- MHz Sweep/Function generator 58 HARDWARE HACKER Synchronous demodulation. Don Lancaster 77 AUDIO UPDATE Do we hear things differently? Larry Klein 71 EDITOR'S WORKBENCH Booting from a PROM Jeff Holtzman Electronics Vol. 61 No. 3 ComputbrDicest PAGE 42 96 Advertising and Sales Offices 96 Advertising Index 8 Ask R-E 97 Free Information Card 14 Letters 79 Market Center 22 New Products 4 What's News > 3) O I ID O w o o o < tfyou're looking for a power supply that combines high voltage, high current, and adjustability, then your search has ended. This month's cover project offers two fully float- ing, adjustable 50-volt, 5-amp sup- plies, along with a fixed 5-volt 3-amp supply. The price of the supply is a steal when compared to commercially available units. Even better, a modu- lar design allows you to build in only the features you need, keeping costs down even more. For all the tech- nical and construction details, turn to page 31, THE APRIL ISSUE GOES ON SALE MARCH 1 BUILD THE MORSE DETECTOR This sophisticated project decodes morse code and RTTY signals. BUILD A SOLID-STATE WIPER CONTROL Beat those April showers with this easy-to-build project. ONE-CHIP FREQUENCY CONVERTER An in-depth look at the Signetics NE602. GLITCHES IN THE POWER LINE Everyone involved in electronics should understand the causes of and cures for power-line disturbances. AUDIO-AMP COOKBOOK Automotive applications for power op-amp IC's, As 9 service to readers. RADIO- ELECTRONICS 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 readers, RADIO-ELECTRONICS disclaims any responsibility for the safe end proper functioning of reader- built projects based upon or from plans or information published in this magaiine. Since some of the equipment and circuitry described in RADIO-ELECTRONICS may relate to or be covered by U-S. patents. RADIO-ELECTRONICS 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-ELECTRON ICS. (ISSN 0033-7802) March 1990. Published monthly by Gernsback Publications. Inc.. 500. rJ Si-County Boulevard . Farm i n g dale. NY 1 1 735 Seco n d -Cla ss Postage pa i d at Farm i ng d ale , NY and additional mailing offices. Second-Class mail registration No. 9242 authorized at Toronto, Canada. One -year subscription rate U.S.A. and possessions $17.97. Canada S23.97, all other countries $26.97. All 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 $2.50. ■? 1990 by Gernsback Publications, Inc. All rights reserved. Printed in U.S.A. POSTMASTER: Please send address changes to RADIO-ELECTRONICS. Subscription Dept,. Bon 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. Electronics Hugo Gernsback (1884- 19671 founder M. Harvey Gernsback, editor-in-chief, emeritus Larry Stockier. EHF. CET, editor-in-chief and publisher EDITORIAL DEPARTMENT Brian C. Fenton, editor Marc Spiwak, associate editor Daniel Goodman, technical editor Teri Scaduto, assistant editor Jeffrey K. Holtzman computer editor Robert Grossblatt, circuits editor Larry Klein, audio editor David Lachenbruch contributing editor Don Lancaster contributing editor Richard D. Fitch contributing editor Kathy Campbell, editorial assistant ART DEPARTMENT Andre Duzant, art director Injae Lee, illustrator Russell C. Truelson, illustrator PRODUCTION DEPARTMENT Ruby M. Yee, production director Robert A. W. Lowndes, editorial production Karen S. Tucker advertising production Marcella Amoroso production assistant CIRCULATION DEPARTMENT Jacqueline P. Cheese boro circulation director Wendy Alanko c ircu latio n ana iys t Theresa Lombardo circulation assistant Michele Torritlo. reprint bookstore Typography by Mates Graphics Cover photo by Diversified Photo Services Radio-Electronics is indexed in Applied Science <£ Technology Index and Renders Guide to Periodical Liter- aiu/e. Microfilm & Microfiche editions are available. Contact circulation depart- ment for details. Advertising Sales Offices listed on page 96. ill i G The Audit Bureau of Circuialion Now electronics technicians can get into VCR Servicing quickly and easily Learn professional VCR servicing at home or in your shop with exclusive videotaped demonstrations Today, there are more than 10 million VCRs in use, with people standing in line to have them serviced. You can bring this profitable business into your shop with NRI professional training in VCR servicing. This top-level training supports the industry's claim that the best technicians today are those who service VCRs. Integrated Three- Way Self-Teaching Program In one integrated program, NRI gives you a study guide, 9 instructional units, 2 hours of video training tapes accompanied by a 32-page workbook that pulls it all together. At home or in your shop, you'll cover all the basic concepts of video recording, mechani- cal and electronic systems analyses, and the latest troubleshooting tech- niques. Your workbook and instruction- al units also contain an abundance of diagrams, data, and supplementary material that makes them valuable addi- tions to your servicing library. The "How-To" Videotape Your NRI Action Videocassette uses every modem communications tech- nique to make learning fast and easy. You'll enjoy expert lectures and see animation and video graphics that make every point crystal-clear. You'll follow the camera eye into the heart of the VCR as step-by-step servicing tech- niques are shown. Both electronic and mechanical troubleshooting are covered . . . including everything from com- plete replacement and adjustment of the recording heads to diagnosing micro- processor control faults. Plus Training On AH The New Video Systems Although your course concentrates on VCRs "covering Beta, VHS, and W U-Matic commercial VCRs, NRI also brings you up to speed in other key areas. You'll get training in capacitance and optical video disc players, projec- tion TV, and video cameras. All are in- cluded to make you the complete video technician. There's even an optional final examination for NRI's VCR Pro- fessional Certificate. Covers Beta and VHS systems with actual instruction on videotape. The Best Professional Training This exclusive self-study course has been developed by the professionals at NRI. NRI has trained more television technicians than any other electronics school! In fact, NRI has consistently led the way in developing troubleshoot- ing techniques for servicing virtually every piece of home entertainment equipment as it appears in the market- place. Satisfaction Guaranteed . . . 15-Day No-Risk Examination Send today for the new NRI Self- Study Course in VCR Servicing for Professionals. Examine it for 15 full days, look over the lessons, sample the videotape. If you're not fully satisfied that this is the kind of training you and your people need to get into the profit- able VCR servicing business, return it for a prompt and full refund, including postage. Act now, and start adding new business to your business. Special Introductory Offer This complete VCR training course with two hour videotape is being offered for a limited time only, on orders received from this ad, at our low introductory price of $179.95. Save $20 by acting now! NRI Training For Professionals McGraw-Hill Continuing Education Center 4401 Connecticut Ave Washington, DC 20008 \Zl_j 1 C ' Get me started in profitable 1 JLrtJ • VCR servicing. Rush me my NRI self-study course in VCR Servicing for Professionals. I understand I may return it for a full refund within 15 days if not completely satisfied. PLEASE SPECIFY TAPE FORMAT DESIRED □ VHS □ BETA Name (please prim) Company Strew NRI m i:nil NRI Training For Professionals McGraw-Hill Continuing Education Center 4401 Connecticut Avenue Washington,DC 20008 Cily/Slale/Zip_ Enclosed is ray D check D money order for S 119.95 (DC, residents add 6* tax) Make check payable to NRJ Charge lo □ VISA □ MasterCard . Interbank Number Card Number_ Signature- Expiration Dale_ 2 > O CO CO o ( required for credit card sales) WHAT'S N EWS o H O □ < New path for com A team of IBM researchers led by Dr. Mordehai Heiblum have demonstrated that fast-moving "ballistic" electrons can be focused and steered as they travel at very low temperatures through gallium arsenide— a semiconduc- tor material that holds promise for use in future computers. The re- sult of studies at the Thomas J. Wat- son Research Center in Yorktown Heights, NY (where the same re- search group previously demon- strated that ballistic electrons can travel through ultra-thin layers of gallium arsenide at speeds greater than 1,000,000 mph), the discovery raises the possibility that 21st-cen- tury computer architects might possibly be able to use directed beams of electrons in computer- chip circuitry. Normally, electrons moving through a semiconductor travel only a very short distance — known as the "mean free path" — before they collide with atoms, other electrons, or impurities. That causes the electrons to scatter and, in the process, to lose energy and change direction. The mean free path in those experiments is lengthened by reducing the tem- perature to -450°F, which greatly reduces the normal motion of atoms in the semiconductor mate- rial, thus reducing the chance of collision with electrons. That al- lows the electrons to travel "bal- listically" — in other words, with- out scattering. The experimental setup was a type of microelectronic switch that involved "injecting" high-energy electrons on one side of a 2-mi- cron region of semiconductor ma- puter electronics? TO FOCUS AND STEER BALLISTIC elec- trons, traveling through a tiny region of the semiconductor material gallium arse- nide, scientists "injected" them through an injector (I), focused the electron beam with a tiny metai lens (L), and "collected" the electrons in three areas (CI, C2, and C3). terial, and "collecting" them at the other side. The electrons traveled ballistically through a "two-dimen- sional electron gas," a region free of impurities that might cause en- ergy-wasting collisions. The scientists applied a voltage to a curved lens as the electrons passed underneath it, causing the electrons to slow down and be focused. To demonstrate that the path of travel could be controlled, they applied a differential voltage across tiny metal gates as they in- jected the electrons into the semi- conductor. They were able to steer the electrons about 60 degrees off the original path over a distance as long as two microns. (One micron equals 1/25,000th of an inch.) Substantial development hur- dles would still have to be crossed before the controlled electron beams could find any practical ap- plication in future computer tech- nology. Satellite capabilities coming down to earth? The first field trial of fiber-optic networks for broadcast television began in December 1989 with ABC's transmission of live televi- sion from New York to seven cities across the country. The first of five consecutive trials coordinated by Bellcore (Livingston, NJ) used coast-to-coast fiber-optic links to determine how efficiently net- work television studios can broad- cast programming to affiliate sta- tions using a land-based alter- native to satellites, which are now used almost exclusively by major broadcasters to Jistribute and col- lect programming. Besides ABC, CBS, FOX, NBC, and PBS are participating — along with some 50 television stations, manufacturers, suppliers, interex- change carriers, and exchange car- riers. The trial networks, estab- lished between Atlanta, Boston, Indianapolis, Los Angeles, Min- neapolis, New York, St. Louis, and Washington, transmit con- ventional television signals at 45 megabits per second (DS3 rate). The signals travel over a two-way, tree-branch-like network that per- mits broadcasters to distribute programming simultaneously to any number of affiliate stations and to receive programming from those stations individually. Eight Bell operating companies and five interexchange carriers are provid- ing the fiber-optic networks for the trials, and several suppliers are providing equipment ranging from video and audio codecs to a new multi-cast switch. Various factors have combined to make the tests possible, includ- ing the declining cost of a DS3 channel and the availability of fi- ber optics (about 300 cities are connected by fiber optics and are capable of transmitting video at the DS3 rate). Space is limited on satellites, which are also subject to the problems of aging. Further, fi- ber networks offer near-in- stantaneous customizing of a program's destinations, lack of sig- nal interference, security from un- authorized receivers, multiple simultaneous audio-channel ca- pability, and the flexibility to make every network affiliate a program source. R-E 5 WAYS TO STOP WASTING TIME IN ELECTRONICS. , Stop wasting your time soldering. Save hours of soldering, desoldering, resoldering with Quick Test™ sockets and bus strips. Connect/ disconnect resistors, capac- itors, transistors, ICs, etc. as fast as you can push in/pull out leads. Interlock for limit- less expandability. Priced as I low as $1.60, you'll wonder how you've done without them! 2 Stop wasting your time breadboard ■ ing. Here are three popular PROTO BOARD* Brand solderless' breadboarding systems that meet any budget or time schedule. First the diminutive PB-10's 840 contact points and 3-color binding posts. PB-102has 1,240 tie points, accepting up to 12 16-pin ICs Finally, PB-103, with 2,250 contact points, and up to 24 16-pin capacity. They're affordable, American-made lifetime guaranteed. You'll soon see why PROTO BOARD Brand is Today's Standard for Quality in Breadboarding. Stop wasting your time jury-rigging large numbers of circuits. Here are two oversized PROTO BOARDS Brand, with expanded area, tie points, and more to keep your ideas together. PB- 104 features 3,060 tie points, which can handle to 32 16-pin ICs with ease. Four color coded binding posts, and roomy 9.2" x 8" metal panel make it big. ..but simple. The humungous PB-105 lets you load up to 48 16-pin ICs, and much more onto its 5-color coded binding posts and 17 sockets, for over 4,560 contact points. Lifetime guarantee American- made. Affordably priced 4 3. Stop wasting your time plugging- in external power. We've added the power to the breadboard. And, what power! Up to triple voltage power, + 5V, + 12V, - 12V, reg- ulated/current limited and DC. Up to 2,250 tie points, with 24 IC capacity and 14 pin DIPs. Now you can create, test and modify TTL, CMOS, Op-Amps and even microprocessor circuits. Plus, there is the standard Global Lifetime Guarantee on the sockets. And, wait 'til you see the modest prices! PROTO BOARD BRAND 5.^: Stop wasting time designing computer circuits. Now you can use your solderless breadboard concepts for designing accessory circuits. PROTOCARD® is a PROTO BOARD Brand which fits any standard slot in your IBM, PC/XT or PC/AT computer. Some modules even include built-in basic decoder circuits for memory and I/O addressing. Breadboard areas up to 3,360 contact points. Buffered versions eliminate loading of pc buses. Call toll-free for details GLOBAL 1-800-572-1028 SPECIALTIES Global Specialties, An Interplex Electronics Company. 70 Fulton Terrace. New Haven, CT 06512. Telephone: (203) 624-3103. $ Interplex Electronics 1989. All Global Specialties breadboarding products made in USA. O X CIRCLE 193 ON FREE INFORMATION CARD A001 1 Video News DAVID LACHENBRUCH, CONTRIBUTING EDITOR o z o (Z I W _i W Q D < • LCD projectors. Some technologies advance slowly, some rapidly. An example of the latter seems to be LCD projection. TV, which uses liquid- crystal devices as light valves, or shutters. Those projectors can throw a large picture on an external screen. The first such projector to "be marketed, introduced in the autumn of 1988 by Eastman Kodak (now being sold under the Seiko Epson name), had the drawback of a very coarse picture. Its three LCD's (one for each primary color) had resolution of 70,400 pixels. Last year, Sharp introduced its own version with much improved performance, with resolution of about 89.500 pixels. Evolution continues with a high- resolution version jointly introduced in Japan by JVC and Seiko, which provides resolution of 210,000 pixels. The LCD projectors are still high- priced ( $3,500 to almost $7,000), but many video engineers believe that the LCD lightvalve is the key to giant-screen TV's future. • Giant TV tabes. At a time when many critics are saying that there is no American TV- receiver industry, worldwide television manufacturers are sharply increasing their investment in the United States to build giant- screen picture tubes here. Before the current wave of expansion began last year, the largest size picture tube produced in the U.S. was 27 inches, measured diagonally. Most of the expansion is in plants to manufacture tubes 30 inches and larger, in some cases with provisions for later conversion to production of widescreen tubes for High-Definition TV (HDTV). Major big- screen plants or additional facilities in the United States have been announced so far by Thomson Consumer Electronics (RCA and GE brands) to make 31- and 35-inch tubes; by Toshiba for 30- and 32-inch tubes; and by Philips (Philips, Magnavox, and Sylvania) for 27-inch tubes. Hitachi reportedly is seeking a plant in the United States to build giant tubes. • Interactive video. Will the videodisc of the near future be based on the audio compact disc? Major developments seem to indicate that interactive audio-video discs with full realtime motion are in the works. Two systems — both using standard five-inch CD's — are in competition. Although the Compact Disc- Interactive (CD-I) was the first to be announced, its video capabilities heretofore have been confined to still motion and very limited animation. A competing system called Digital Video-Interactive (DVT), developed at the Sarnoff Research Center and being prepared for production by Intel, claims full-motion, high- resolution video. Not to be outdone, Philips, one of the developers of CD-I, recently announced the breakthrough to 70 minutes of full-motion video. Both systems could be offered to the public late this year or early next year. Intel is expected initially to aim DVI at computer users, while Philips, Sony, and others probably will push CD-I as a consumer- entertainment and -education medium. In addition to its interactive capabilities, the new type of video CD-ROM could become the first all- digital video product, eventually replacing the current 12-inch laserdisc (which has analog video and both analog and digital audio). • HDTV progress. The tide is turning in American research on HDTV. The Advanced Television %-stem Committee (ATSC), which is coordinating development and testing of proposed systems for the United States, notes that as tests get nearer many proposed systems are changing. The FCC has ruled that any American HDTV systems must be compatible with existing television, and that no system may use more than two 6-MHz channels. Most of the initial proposals envisioned the addition of a second "augmentation" channel to an existing conventional channel to add the extra lines of resolution and the "ears" for the wider picture. Now, ATSC Chairman James McKinney notes that most of the systems have switched to "simulcast" systems — those that leave the current conventional channels alone and add a separate 6-MHz channel to provide a complete HDTV picture. McKinney said recently that four of the five remaining proposals for HDTV systems envision simulcasting, R-E SM Radio /haek Part/ Place GREAT VALUES FOR YOUR PROJECTS AND FIX-UPS Parts Special-Order "Hotline" ICs. Crystals, Tubes, Lots More! Your Radio Shack manager can special - order a wide variety of parts and accesso- ries from our warehouse— Long-Life tubes, linear and digital ICs, phono cartridges and styll, crystals, transistors, diodes, even SAMS Photofacts 7 . No handling charge, no shipping charge— Just fast delivery to the Radio Shack near you! PC cords & Multiconductor Cables , . „__ _^ (1) Double-Shielded Cable. UJ *w ^^^— \&x g-Cond. #278-775, 59* per ft. ^^^^^^^T 25-Cond. #278-776, 1.19 per ft. (2) CEE-Type Power Cord Extension. #278-1259 4.99 (3) Power Cord with 90- CEE Connector. #278-1260 5.99 (4) PC Power Cord with Straight CEE Connector. #278-1257 . . 3.99 (5) Snap-Together RFf Choke Core. #273-104 Pkg. of 2/7.95 Brighter leds (1) ffe (2) **, (3) (1) Red Jumbo. #276-086, 4.99 (2) Red Blinking. #276-020, 3.99 (3) Brilliant Red 2000 mcd. 20 mA/1.85VDC. #276-087 .... 1.69 Grade Au+ Plugs 7/77 Gold-Plated W (1) Deluxe Phono Plug. For 6mm OFC cable. #274-860 4.99 8mm Plug. #274-861 5.99 (2) Three -Conductor "a" Phone Plug. Stereo. #274-858 3.49 (3) Two-Conductor V*° Phone Plug. Monaural. #274-855 . . 3.49 Hot Hobby items rm " w # (1J 1.5-3V DC Motor. 8300 RPM. Vh x ' W dia. #273-223 . . . . 99t (2) Piezo Buzzer. #273-074, 2.99 (3) 1:1 Audio Transformer. 600 to 900Q #273-1374 3.59 Tantalum Caps Low As 59* High Capacity MF WVDC Cat. No. lirf: 0.1 0.47 1.0 35 35 35 272-1432 272-1433 272-1434 .59 .59 .59 2.2 10 22 35 16 16 272-1435 272-1436 272-1437 .69 .79 1 19 so- Range Multimeter 0.5" LCD -7Q95 Display / Zf Built-in capacitor and transis- tor test functions make this an incredible value! Continuity sounder, low-battery indicator, diode checker. Measures to 1000 VDC and 750 VAC, 10 amps AC/DC, resistance, ca- pacitance, transistor gain. Bat- tery extra. #22-194 .... 79,95 Battery Special-Order Service In addition to our large in-store stock, Radio Shack can now supply almost any battery manufactured! Batteries are sent from our ware- house to the Radio Shack near you. You never pay a postage charge! Replacement Rod Antennas (2) (3) QBE Sea ions Extended 30 ft" 34*" 39W 11 'ft" 16*" 24" 13 'A" 270-1401 270-1402 270-1403 270-1411 270-1412 270-1413 270-1414 Each 2,99 3,69 IK» 2 :■-" 2.79 3.99 2.49 n Sections Extended Cat. No. Each 3 5 28" 270-1405 3.19 - 5 15'fe" 270-1406 2.79 — 6 72" 270-1408 3.99 - 5 13" 270-1407 2.79 — 6 17%" 270-1409 2.59 - 6 16" 270-1410 2.99 Thermo Module LCD F/C display. Use as ther- mometer or add simple circuitry to control tan, buzzer, heater. Pro- grammable. #277-123 19.95 Solder Products M. (2) jjfcifc; ■*- (3)— JB=as*l I (D We Have It All! (1) Rosin Soldering Paste Flux. #64-021 1.79 (2) Solder-Weld Silver-Searing Paste. #64-029 2.59 (3) Lead-FreeSolderHandy-Pak. .032", 0,25 oz. #64-025 .... 1.99 .062" 0.50 oz. #64-026 1.49 High-Style Project box Give projects that professional look with this classy two-piece enclosure. Interlocking de- sign lets you shorten box if desired. Polycarbo- nate material is impact resistant, yet easily drilled. Accepts PC board and 9V battery. 5^e x 7>h x 1 Vis". #270-257 4.99 Pocket (2) Guides 0) Ull '|l'|" (1) Color Codes. id s all resistor, ca- pacitor, and inductor values. #271-1210 69C (2) Ohms Law/Parallel Resist- ance Slide Chart Calculator. #271-1211 59* Switch values w (1) SPST Momentary Pushbut- ton. 3A/125VAC, #275-1556. 1.99 (2) Lighted SPOT Push-On/Off. 3A/125VAC. 12V lamp. #275-676 6,49 B-Board and Jumpers Ifl) (2) (1) Archer 7 Universal Breadboard. Molded 2Vj x 6'fe" board on a 7 x 4" steel base, rubber feet. 640 plug-in points, three binding posts for fast circuit design. #276-169 19.95 (2) Breadboard Jumper Wire Kit. Has 140 insulated wires in a handy snapshut plastic box. #276-173 Set 4.95 Over 1000 items in stock! Binding Posts, Books, Breadboards, Buzzers, Capacitors, Chokes, Clips, Coax, Connectors, Fuses, Hardware, ICs, Jacks, Knobs, Lamps, Muititesters, PC Boards, Plugs, Rectifiers, Resistors, Switches, Tools, Transformers, Transistors, Wire, Zeners, More! Prices apply at participating Radio Shack scores and dealers Battery-powered items exclude batteries Radio /haek The Technology Store 8 A CHVkSlON OF TANDY CORPORATION > o X to o CIRCLE 78 ON FREE INFORMATION CARD Ask R'E WRITE TO: ASK RE Radio-Electronics 500-B Bi-Counly Blvd. Farmingdale, NY 11735 z o cc H o LU _1 LU 6 Q 3 AUTO NINTENDO We have a Nintendo system and would like to be able to use it in our van when we're traveling. Our smalJ portable TV works fine when operating off the car's 12 volts, but the Nintendo requires 9 volts at about 850 milliamps. Is there any- thing that can be done to enable the Nintendo to be powered by the car's electrical system? — M. Mc- Calla, Lanett, AL There are lots of ways to do that, and which one you choose depends on how much work you want to make for yourself. The answers range from a simple store-bought solution to a few hours on the bench building a box of your own. The choice is yours. If you're only interested in re- sults, there's no doubt that the easiest thing to do is stop at your local electronics store and see what's hanging around on the shelves. The adapters should be fairly easy to find because they're also needed by people who want to run a compact disc player off the car's electrical system and that, as we all know, is a very pop- ular thing to do. There are two things to watch out for when you're shopping for an adapter. The first is that it can supply the correct voltage at the required current levels, and the second has to do with the me- chanical connection at the power plug. You shouldn't have any trou- ble finding an adapter that can supply the proper voltage and current since compact-disk play- ers usually want about the same amount of power. Assuming that you do find one, be very careful to check the voltage polarity at Yin W 180S OUT ^ou-r -h soo /6 V ^ * / 3 ' * . GA/D \2, FIG.1 the power plug. There's unfor- tunately no standard whatsoever about assigning plus and minus. Some adapters put ground on the center terminal and others put it on the collar. The polarity should be marked on the adapt- er, and your Nintendo probably has it embossed on the plastic case. Double-check everything with a meter before you make any connections. If it is back- wards, cut the wire and splice it correctly. It would be a lot better to resolder it at the plug, but most of the adapters use molded plugs. If you can't find an adapter in the store, you can build one using the circuit in Fig. 1. That is just a simple 7805 regulated sup- ply with the ground leg lifted to raise the output voltage. You can get 850 mA out of a 7805, but you'll have to heat-sink it prop- erly to avoid thermal shutdown. Build the circuit in a plastic box and rotate the pot until you find the point where it's putting out nine volts. You can substitute an LM317 for the 7805 if you're really wor- ried about drawing that much current, but a well-heat-sinked 7805 should be fine. And even though the Nintendo is rated for 850 mA, I doubt that it really re- quires that much. CHIP REMOVAL I have to repair my audio ampli- fier and, after spending some time on the circuit, I'm pretty sure that the problem is a bad operational amplifier. My problem is that the chip, like all the others in the am- plifier, is soldered directly to the board. What's the best way to get the chips off the board so I can test them? — F. Geoffrey, New York, N.Y. As sad as I am to say this, I don't believe there's any abso- lutely safe way to unsolder IC's from a circuit board. The best way I know to get a chip off a board with the least risk of damage is to use a solder pot, a spring-loaded extractor, and a steady hand. You'll need enough solder in the pot to form a meniscus on the top. Once the solder is melted, put the spring-loaded chip extractor under the IC and carefully lowerthefoil sideof the board into the solder. As soon as the solder on the board melts, the chip should pop out of its holes. You'll probably wind up with some solder bridges on the board afterwards, but you can easily clean them up. If the board is double-sided or, worse yet, a multilayer board, the chances of success with that method are going to go from so- so to just about nonexistent. Sol- der has a nasty habit of leaching its way into places where it shouldn't go, and the more layers there are, the more places the solder can creep. I've removed IC's using that method but, no matter how care- How to build a high-paying career, even a business of your own, in computer programming. baud internal modem, 640K RAM, disk drive, monitor, and invaluable programming software — BASIC, Pas- cal, C, and COBOL — all yours to keep. 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If you suspect an IC of being bad, you're better off upgrading your suspicion to a certainty and give up the idea of safely un- soldering the chip. Take a pair of cutters, snip the legs as close to the IC body as possible, and un- solder each lee from the board. Once you do that, you can clean the board, solder in an IC socket, and replace the chip with one you know is good. OVERPOWERING AM Every time I turn on my stereo I can hear a local AM station in the background. Is there anything I can do to get rid of it?— J. Saffir, Miami, FL You can buy the station and close it down, but that's probably w o z o EC \3 in _l LU o Q < 12 OPTOELECTRONICS You Have Counted on Us for 15 Years You have counted on OPTOELECTRONICS Hand Held frequency Counters to be the best quality, to be affordable and reliable. We have been there for you with Frequency Counters that are compacl and ultra sensitive. 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If you've still got a problem, try bypassing the inputs with small silver-mica capacitors. A good value to start with is 10 pF, but you can use a higher value if the radio station doesn't disappear completely. Don't go much over 470 pF be- cause, above that, you'll be start- ing to filter out some of the au- dio. You'll know when that's happening because the high fre- quencies will be the first to go. Keep the capacitor leads as short as possible or you'll be making the problem even worse. As a matter of fact, solder the leads right on the lugs of the con- nector inside the amplifier — and don't forget to turn off the power before you open the case. To be on the safe side, unplug the am- plifier from the wall as well as turning it off. VCR CONVERSION I recently returned from a post- ing in England, and I brought back a VCR that I bought there. The ma- chine is set to work off 240 volts at 50 cydes, so I can't use it here. Since it's a really good VCR with- out many hours of use, can you give me an easy way of converting it to work here in the USA? — C. Meyer, Washington, DC Aside from ripping out the en- tire guts of the machine, and re- placing them with American- standard parts, there is no sim- ple solution. Not only are the power requirements different, but the electronics in the ma- chine are designed to work with the English PAL video standard, and not the American NTSC stan- dard. To put it mildly, the two are somewhat different. It would ac- tually be a lot simpler and cheap- er to go out and buy the VCR that you need, rather than try to mod- ify one type of VCR to work with the other format. R-E CIRCLE 191 ON FREE INFORMATION CARD FOR FASTER SHIPMENT CALL 1-800-729-7323 OR FAX 1 -609-273-7760 Special Engineering Edition What's better than speed reading? Speed Learning. Speed Learning has replaced speed reading. It's a whole new way to read and learn. 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If, at the end of that time you are not convinced that you would like to master Speed Learning, simply return the program for a prompt refund. (See the coupon for low price and convenient credit terms.) r RISK FRE ORDER FORM ~ YES! I want to try Speed Learning Engineering Edition for 15 days without risk. Enclosed is the first Of 4 monthly payments of $36.25.* If I am not completely satisfied, I may return it for a prompt refund. I I SAVE 57.00! I prefer to pay the $145.00 now, and save the $7,00 shipping & handling charge. I may still return the program for a full refund. Method of payment: ( Fed erai Tax Ded uci i bi e) r : Check or money order payable to Learn Incorporated D Charge to: □ Visa DMCD Am Ex DDiscover Card# Exp. _ Signature _ Phone [„ Name Address .. City- State . .Zip. "Plus S7.00 shipping and handling. For.New Jersey residents, sales lax will be added. nui, Dept CA-02. 113 Gaither Drive, EleClrOlliCS Mt. Laurel. W 08054-9987 > o I CO CO o 13 Letters AAQ/O - EL ecTMONfes soo-3 at-Qouffrr soule. mad CIRCUIT-BOARD SUPPLIES A letter from Dr. Barry C. Mears ("Letters," Radio-Electronics, Janu- ary 1990), referring to Designer's Notebook in the November and December issues, stated that KTl sells only through distributors, and that only one of those dis- tributors sells the "Kodak chemi- cals" in small quantities. Kepro Circuit Systems supplies anything and everything for peo- ple to produce printed-circuit boards on a prototype or short-run basis. Kepro has been offering KPR products in the form of pre-sen- sitized CopperClad since 1954, and has been distributing quarts of the KPR-3 Photo Resist, along with all the associated KPR products, since the late 1960's, All of their supplies and products are de- scribed in a 32-page catalog. Kep- ro's phone numbers are 314-343-1630 in Missouri, or 800-325-3878 out of state. KEPRO CIRCUIT SYSTEMS, INC. 630 Axminister Drive Fenton, MO 63026-2992 SIMPLE CIRCUIT BOARDS I would like to comment on "Hardware Hacker" (Radio-Elec- tronics, December 1989). I take ex- ception to some of Don Lan- caster's views on creating etched circuit boards. I have been designing and etch- ing circuit boards — as, I expect, have many of your readers — for over 12 years. I have tried all the available methods, and have read g most of the articles on the subject z in electronics magazines. § I have found that the quickest o method is the direct method using lij Radio Shack Dry Transfers 5 (276-1577). It works great for si ngle- 5 sided boards as long as you bur- x nish the design when finished. 14 One of the "stupid" (according to Don Lancaster) things that I do is to use ferric chloride, also from Radio Shack. I seem to have no problem producing clean, sharp traces. The only problem I run into using that method is that as soon as I finish and have the board in its enclosure, my friends all want du- plicate boards so they can build the same project, so I'd have to start all over again. Not on your life! Instead I use the second method, which is to screen print the board and make two or three extras. With the proper registration I can produce single- or double- sided boards with excellent re- sults. The second "stupid" thing that I do is to etch the boards with the resist side up in a glass or plas- tic container. I have never yet had a board come out bad. The only time they've been bad is when I've flipped the board resist-side down and the resist has become scratched and left a gap in the traces. If any of your readers are inter- ested, I have available an instruc- tional video tape that shows the hows and whats of screen-printing circuit boards. For information, send an SASE to: FRED AYRES 4423 West 69 Brooklyn, OH 44144 PROBLEM-FREE PC BOARDS One of the features that I always look forward to reading in Radio- Electronics is "Hardware Hacker," but after reading that column in the December issue I must pro- test. Don Lancaster's diatribes will certainly scare away more printed- circuit-board makers than create them. Mr. Lancaster must have had some bad experience making PC boards by the direct method, but the method is not (as he says) "... more hassle than it is worth, and ends up just about totally worth- less." I have made many circuit boards, all by the direct method, and have not had a single failure. All are one-of-a-kind, and were made in a lot less time than if I had used any of his recommended al- ternative methods. Contrary to what Mr. Lancaster says, one prob- lem is to get the pattern on the copper with something that will truly resist the etching solution. Fingerprints, etc., won't hack it. I've had bad results on test pieces from the commercial inking pens and ended up using shellac tinted with an organic dye. It is cheap, easy to use, and easy to clean off the boards. Mr. Lancaster says that at one time ferric chloride was used as the etchant. Ferric chloride is still being used by the majority of mod- ern commercial circuit-board manufacturers — and by me. It is efficient and has an indefinite stor- age life, even though it does stain. From what I have read, ammonium persulfate has a short life and must be purchased from new stocks. Scrubbing circuit-board mate- rial at 2 minutes per square inch is a ridiculous waste of time. A few seconds with a kitchen sponge and Comet cleanser does the job very well. I almost always etch boards face-up, unless I am reus- ing some old solution and the vol- ume is not enough to cover the board very well. (And, when I make a double-sided board, one side necessarily will be face up.) I etch the boards in rectangular Pyrex baking dishes. I find that if the solution is kept moving, there HITACHI SCOPES AT DISCOUNT PRICES Digital Storage Scopes VC-6025 20MS/S 50MHz Bandwidth 2K Word Memory Capacity $2349.00 Advanced storage functions create new dimensions In scopes such as one shot observation, flicker free display, bright display for even high speed event, trace observation for low speed event, hard copy by plotter and daia output to computer, VC*6Q45 1O0MHZ 40MS/5 4K word Memory cap (call) All Hitachi scopes include probes, schematics, and Hitachi's 3 year worldwide warranty on pares and labor. Many acces- sories available lor all scopes. V-212 **•"•*_•• $435 List $595 Save $160 DC to 20MHz Dual Channel V-1060 List $1595 DC to 100MHz Dual Channel Delayed Sweep CRT Readout Sweep Time Autoranging Trigger Lock 2mV Sensitivity LIST PRICE V-42J 40MHI D.T., ImVsens, DC Offset Vert Moos Trigger, Alt Mag $940 $740 V-423 40MHz D.T., 1 mV sens, Delayed Sweep . 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Meter $179 Modal AM/FM-1 08 $26.95 Circuits are laid out in systematic order on an ever- sized PC board for easy understanding of the flow of radio signals, from antenna to speaker. Complete course includes all parts, PC board and training manual. When completed you will be proud to dis- play your masterpiece. 7 Transistor AM RADIO KIT WE WILL NOT BE UNDERSOLD! C &. S SAT FS INC 15 Day Mone y Back Guarantee UPS Shipping: 48 states 5% r— ,^ s R^ ood . Decrfkld. IL 60015 2 Year Warranty pm «*^ to „™ ($10 Max) IL Res., 7% Tax P^gg (80 n) 292-771 1 (708) 541-0710 WRITE FOR FREE CATALOG CIRCLE 109 ON FREE INFORMATION CARD 2 > 33 O X 8 15 is no problem at all doing it face up. I haven't had any direct experi- ence with sensitized boards, but friends have sensitized their own boards and had satisfactory re- sults. They say it was simple, and there were no problems. I have two board designs that I want to make about 60 boards from, and I hope to do it with silk screen — otherwise it will be with commer- cially sensitized boards. KENNETH E. STONE Cherryvale, KS COMPARING CD PLAYERS The "Audio Update" column in the December 1989 issue of Radio- Electronics left the reader with the impression that all CD players sound the same and the only im- portant thing to consider when se- lecting a player is the features. While Larry Klein did state that in the ABX test conducted in Stereo Review, all of the players were in the $750-$2500 price range, an im- portant point that was not empha- CORRECTION In Fig. 2, in the "RGB-to-NTSC Converter" story (Radio-Elec- tronics, December 1989), the junction of XTAL1 and C3 should not be connected to any other components. In Fig. 5, the vid- eo output connector pins were mislabeled. Pin 1 should be 4, 5 should be 8, and 9 should be 12. Incidentally, the circuit will not run with EGA. sized. I agree that when compar- ing CD players in a particular price range they will all sound essen- tially alike. However, a "top-of-the- line," $1500 unit will always sound different (i.e., better) than a $300 model. That is due to several fac- tors — probably the most impor- tant is that the $1500 model most likely will use dual digital-to-ana- log convertors (18 bits or more) with at least 8x oversampling, while the $300 model probably will use a single D/A convertor (14 or16 bits) with only 2x oversampling. Even the casual listener would be able to differentiate between the two players. I thought that point needed to be brought up. I enjoy Mr. Klein's column. DWAYNE ROSENBURGH Elkridge, MD ETCHING-TANK TIPS First I'd like to say that I enjoy Radio-Electronics very much. I'd like to suggest a better way of working the Plexiglas material used in the article "Make Your Own Etching Tank" (Radio-Elec- tronics, December 1989). If you cut the plastic as described in the arti- cle, you probably found out that a considerable amount of filing or sanding was needed to produce the square edge needed for a good solvent-weld joint. The "score-and-break" cutting method is perfectly fine if you are making plastic window panes, but it makes a messy edge for solvent- welding purposes. The remarks in the article about y z O £E \- O Hi _l LU 6 Q < 16 CIRCLE 199 ON FREE INFORMATION CARD sawing the material are true — but the problem is easy to overcome. To make a good solvent-welding joint, the smoother the cut the better. The smoothest cutting line can be accomplished by sawing with a very fine-tooth blade in a power saw with a rip fence. The melting problem can be overcome by keeping it cool with water. Don't worry about being elec- trocuted; you only need a little water, not a garden-hose full. A pump-spray bottle will do fine. The surface of the Plexiglas need only be kept wet enough so that a small puddle stays around the saw blade or drill bit. Be sure not to push the saw too hard — let the saw do the work. That cutting method will create an edge that requires a lot less fil- ing for a good welding surface and a water-tight joint. STUART D. HARDEE Loris, SC WHEN LESS IS MORE I would like to comment on Michael Catudal's letter ("Letters," Radio-Electronics, December 1989). While I agree with Mr. Catudal that your magazine should feature more articles on new technology, especially some of the newer chips, I disagree that all of the fea- tured projects should be based on the latest state-of-the-art tech- nology. Many years ago, when I was an engineering student, I remember a professor saying that an engi- neer's task will be to find the mini- mum of means that will solve the problem. As an example, he said, anyone could send out a16-ounce hammer for a crew to use to drive carpet tacks — but an engineer would be expected to send out the lightest hammer that could do the job. My boss would really think I was nuts if I used an 80960 with four 27C1024's to solve a problem that an 8039 with a 2716 could han- dle sufficiently. Even though I don't build them, I find many unique and time-sav- ing hints and circuits in most of the projects in Radio-Electronics. I've used many of those circuits, time and time again, in designs. Keep up the good work. CHARLES J. MANCUSO Sandpoint, ID R-E NEXT MONTH IN Po Exciting Features, Projects, Reports, & Columns • BUILD A REACTION TIMER Use it as a game of skill, or to help you improve your reaction time, • BUILD A CUSTOM SECURITY SYSTEM An expandable, adaptable alarm that can be used to protect your home, car, or boat. THE TRANSFORMERLESS POWER SUPPLY High-voltage output, high- current capacity, and no bulky transformer. REVIVING A RELIC Can't afford a new top-of-the- line SW receiver? Then get almost- as-good performance with one of yesterday's workhorses. And there PRODUCT REVIEWS— Yamaha TX-1000U AM/FM Stereo Tuner, Au- dio-Technica ATH-909 Stereo Head- phones, and much more. DX LISTENING— Shortwave fare from our northern neighbors. COMPUTER BITS— Pushbutton computing comes to the PC. is more! CIRCUIT CIRCUS— Infrared re- mote-control circuits for any applica- tion. HAM RADIO — Can't find a tuning coil for a special project? Then why not make your own! SCANNER SCENE— Scanning above 800 MHz. PICK UP nipuiai I ILLLUTIIllS AT YOUR FAVORITE NEWSSTAND, CONVENIENCE STORE, OR SUPERMARKET > D O I to O 17 Equipment Reports to o z o cc o UJ _l UJ 6 Q < THERE IS NO QUESTION THAT PRO- totyping requires organization. While engineers are seldom noted for neatness, they'll be the first to acknowledge the importance of making a neat prototype. There's a simple reason for that: When the circuit doesn't work the first time, a clean prototype is much easier to troubleshoot. If, despite your best intentions, your circuit prototypes seem to al- ways end upinatangledmess,you might need some help from the Wishmaker II Digital Prototype Design Station from Jameco Elec- tronics (1355 Shoreway Road, Bel- mont, CA 94002). The Wishmaker II combines a breadboard with power supplies, test equipment, and more in a convenient and portable package. The entire package is housed in a square, briefcase-like plastic case that measures 13%x14 x 4 3 A inches. The case opens to reveal a large, removable solderless bread- board with more than 3500 tie points. Above the breadboard is a sloped panel containing various test and measurement equipment. The case top, which is removable, holds a box of assorted stripped and p re-formed jumpers, and a set of test leads. The Wishmaker II offers four separate power supplies. Fixed supplies deliver +5 volts at 3 amps and -5 volts at 500 milliamps. Vari- able supplies deliver +1.2 volts to Jameco Electronics Wishmaker II Prototype Design Station A portable, self-contained prototyping station to make your design wishes come true! CIRCLE 38 ON FREE INFORMATION CARD +15 volts and -1.2 volts to - 15 volts at 500 milliamps. Built-in testing The output of the supplies, or the output of any circuit you build, can be monitored using several built-in test instruments. For ex- ample, an analog multimeter can measure DC and AC volts (250 volts maximum), DC current (250 milli- amps maximum) and resistance. Your circuits can also be monitored with the built-in logic probe; red, green, and yellow LED's indicate logic highs, lows, and pulses. Input to the probe can be provided to either a tie-point socket or to a test probe. A three-digit frequency counter can measure signals to 999 MHz in three ranges. Input to the probe is provided to a tie-point socket. Two BCD-to-7-segment de- coder/drivers are provided to dis- play the outputs of digital circuits. Binary inputs are automatically converted for display on 7-seg- ment LED's. While such a circuit would be easy enough to build on the breadboard, its inclusion on the top panel helps to keep the breadboard clutter to a minimum. Along with the monitoring equipment, Wishmaker II pro- vides several devices to provide in- puts for your circuits. The simplest is a bank of eight 3-way toggle switches, that can be manually switched to provide high, low, and floating inputs. The switches are arranged so that in the "up" posi- tion, the output is high, and so on. However, to monitor the outputs, you might want to use the eight LED display drivers. The bi-color LED's turn red with a high level is presented to their inputs, and green when a low is presented. The Wishmaker II can also pro- vide pulses to your circuits. Two pulse switches provide de- bounced pulses. Each switch has two outputs, one normally low, and the other normally high; pressing the switch causes the low output to go momentarily high, and vice versa. A pulse generator provides 50% duty-cycle pulses. Seven discrete frequencies are avail- able, ranging from 1 Hz to 1 MHz. A signal generator provides sine, square, and triangle outputs from 1 Hz to 100 kHz in 5 ranges. Unlike the pulse generator, the output is continuously adjustable. The exact output frequency can, of course, be measured with the built-in frequency counter. If any of the circuits you design on the Wishmaker II need to be connected to a computer, a set of DB-25 connectors makes it easy. One connector, on the side panel of the unit, is internally connected to another DB-25 on the front pan- el. Jumper wires can easily bring the appropriate signals to the breadboard. The Wishmaker II is an wish come true for engineers, techni- cians, hobbyists, and students. Besides being an excellent pro- totyping tool, it would be an excel- lent teaching tool in an electronics lab course. The Wishmaker II is priced at $249.95. A similar device, the $199.95 Wishmaker I analog prototype design station. The Wishmaker I does not offer the fre- quency counter, pulse generator ordebounced pulse switches, but does add a speaker and 4 potenti- ometers. R-E 18 WITH CIE, THE WORLD OF ELECTRONICS CAN BE YOUR WORLD, TOO. Look at the world as it was 20 years ago and as it is today. Now, try to name another field that's grown faster in those 20 years than electronics, Everywhere you look, you'll find electronics in action. In industry, aerospace, business, medicine, science, government, communications — you name it. And as high technology grows, electronics will grow, Which means few other fields, if any, offer more career opportunities, more job security, more room for advancement— if you have the right skills, SPECIALISTS NEED SPECIALIZED TRAINING. It stands to reason that you learn anything best from a specialist, and CIE is the largest independent home study school specializing exclusively in electronics, with a record that speaks for itself. According to a recent survey, 92% of CIE graduates are employed in electronics or a closely related field, When you're investing your time and money, you deserve results like that. INDEPENDENT STUDY BACKED BY PERSONAL ATTENTION. We believe in independent study because it puts you in a classroom of one, So you can study where and when you want, At your pace, not somebody else's, And with over 50 years of experience, we've developed proven programs to give you the support such study demands. Programs that give you the theory you need backed with practical experience using some of the most sophisticated electronics tools available anywhere, including our Microprocessor Training Laboratory with 4K of random access memory. Of course, if you ever have a question or problem, our instructors are only a phone call away. START WHERE YOU WANT, GO AS FAR AS YOU WANT. CIE's broad range of entry, intermediate, and advanced level courses in a variety of career areas gives you many options. Start with the Career Course that best suits your talents and interests and go as far as you want— all the way, if you wish, to your Associate in Applied Science Degree in Electronics Engineering Technology. But wherever you start, the time to start is now. Simply use the coupon below to send for your FREE CIE catalog and complete package of career information. Or phone us, toll-free, at 1-800-321-2155 (in Ohio, 1-800-523-9109), Don't wait, ask for your free catalog now. After all, there's a whole world of electronics out there waiting for you, CIE Cleveland Institute of Electronics, Inc. 1776 Eest 17th Street. Cleveland, Onio 44114 Member NH5C Accredited Member National Home Study Council Cleveland Institute of Electronics, Inc. 177S East T7th Street, Cleveland. Ohio 44114 ARE-162 VESot I want to learn from the specialists in electronics— CIE. Please send me my FREE CIE school catalog, including details about CIE's Associate Degree program plus my FREE package of home study information. Name (print): __ Address: City:. Age: State: Zip: Area Code/Phone No.: /. Check box for G,I. Bill bulletin on educational benefits: MAIL □ Veteran □ Active Duty TODAY! LEARN TV/VCR REPAIR No Previous Experience Necessary Now you can train at home in your spare time for a money-making career as a TV /VCR Repair Specialist No need to quit your job or schoot. We show you how to Ijoubleshoot and repair vjdeoeassette recorders and TV sets, how to handle house calls and shop repairs for almost any make of television or VCR. You learn about TV receivers, tuners and antennas. X-ray emission, the characteristics of sound, how electrical impulses are converted into a TV picture, and much, much more. Tools are included with your course so you can get "hands-on" practice as you follow the lessons stepby step. Send for Tree facts about opportunities in TV /VCR Repair and find out how you can start making money in this great career. B Experts show you what to do, how to 3 do it,., guide you every step oft he way! Everything is explained in easy-lo-understand language with plenty of drawings, photos and diagrams. But if there is ever anything in your lessons you oWi understand, you can write or phone jyour instructor and vou can count on felting an authoritative answer. Send for free facts and color rochure. No cost. No obligation. No salesman will visit. MAIL COUPON TODAY SCHOOL Of TV/VCR REPAIR, fat. DI02Q [gpfct nnJ 925 Oak Street. Scranton. PA 1 B51 5 Please send me free facts on how [ can team TV/ VCR Repair at home in my spare time. No saEesman will visit. Name Address^ City/State^ Phone ( _Age _Apt. #_ Zip ft A Subsxtery cf Naixwal eTrfueaivin C&poraltan CIRCLE 188 ON FREE INFORMATION CARD 20 w> StfSWSSfc Beckman Industrial FG3A Sweep/Function Generator A stable 2-MHz generator with linear and logarithmic sweep. CIRCLE 39 ON FREE INFORMATION CARC FOR MEASURING THE RESPONSE OF AN audio amplifier, finding the reso- nant points of a filter network, or examining any system that oper- ates over a broad frequency range, nothing beats the combination of an oscilloscope and sweep gener- ator. That point was driven home recently when we had the oppor- tunity to examine the FC3A, a new sweep function generator from Beckman Industrial Corporation, 3883 Ruffin Rd., San Diego, CA 92123-1898). The FC3A can provide sine, square, triangle, and ramp signals in seven ranges from 0.2 Hz to 2 MHz. A pulse output, at eitherTTL or CMOS levels (or anywhere in between) is also available. Any of the outputs can be swept either linearly or logarithmically throughout the entire range, or any portion of it. An external vcf Or VOLTAGE- CONTROL LED FREQUENCY jack allows an external signal to vary the frequency of the output; A 0-10 volt signal causes a 1000:1 change in frequency. The selected output can also be amplitude- or frequency-modulated by an inter- nal or external signal. The output amplitude of the FC3A is 20 volts p-p into an open circuit, or 10 volts p-p into a 50- ohm load. The duty cycle of the outputs are continuously adjusta- ble from 1:1 to 10:1. The frequency of the output is displayed on the built-in 5-digit frequency counter. That counter sports an external input, and can be used to measure external sig- nals of up to 10 MHz. The FG3A is ruggedly built in a 9x3x13-inch shielded plastic case and weighs about 4'/i pounds. The front panel features an intel- ligent layout that is dominated by Jhe 5-digit LED display. Switches are grouped according to func- tion, which makes the unit very easy to operate. Using the sweep generator Although the sweep function generator is not one of the most popular test instruments, it is an extremely versatile one. The most common application is measuring the frequency response of ampli- fiers, filters, and other networks. That task is performed by feeding the output of the generator to both the network under test to one oscilloscope channel. The output of the network is fed to the other scope channel. If, for example, you were testing an audio amplifier, the sweep gen- erator would be set up to provide sine waves in the audio-frequency range, and the scope would be set to display both the input and the output. At a glance, you would see the response of the amp over the entire operating range. Using the same technique, it is a simple matter to determine the resonant point of filter networks. Carrying that a bit further, it's pos- sible to identify the value of an unmarked inductor or capacitor, even without an LC meter. Assum- ing you know the value of one of the components, you can set up a simple LC network and manually sweep the generator for a null. Knowing the resonant frequency and the value of one of the compo- nents, simple arithmetic will yield the value of the unmarked part. The FC3A is a unit that has the look, feel, and performance that you might not expect from a $475 sweep function generator. We congratulate Beckman on a job well done, R-E CIRCLE 108 ON FREE INFORMATION CARD TEST METHODS MIKE ROGALSKI Easy impedance measurements IMPEDANCE MEASUREMENTS OFTEN CON- jure up an image of complex test equipment and tricky calculations in- volving at least a square root or two. However, none of that is necessary if you understand a relationship that ex- ists between impedance and decibels. That relationship is this: If you cut your load impedance in half, the out- put of the circuit drops by 3 dB . Using that knowledge, it's easy to design a simple piece of test equipment that will give you the AC impedance of a circuit, and all you need is a potenti- ometer, a switch, and a VOM having resistance and decibel scales. Switch- ing between the dB- and DC-resis- tance readings will yield the effective AC impedance of a circuit at a given frequency. FIG, 1— THE EFFECTIVE AC IMPEDANCE of a circuit can be determined using this circuit. Figure I shows the simple test cir- cuit, which is a simplification of the Wheatstone bridge used in complex impedance-measuring equipment. To use it, connect the two test probes, a and B, across the circuit under ques- tion. Then take a relative reading on the dB setting of the meter with the potentiometer out of the circuit (SI open). If possible, make the circuit's output as high as you can in order to make the reading as accurate as possi- ble. Next, place the potentiometer in the circuit (close SI) and adjust it to a point where the meter reads 3 dB lower than the first reading. Without changing the setting of Rl, discon- nect the circuit under test and measure the DC resistance of the potentiome- ter; it will be the equivalent DC resis- tance of the AC circuit at the frequency used during the test. You may want to take several leadings at different frequencies. Troubleshooting potentiometers There is a unique way to check a potentiometer's wiper for continuous contact on the resistive element. The circuit shown in Fig. 2 enables you to place a potentiometer in an audio-op- erating environment so you can hear how it affects an audio signal without the distraction of the music itself. The circuit is particularly useful in record- ing studios, where audio faders tend to get a lot of wear and tear, but it is equally useful in other situations. iTENItOMETER AUDIO a i to o CIRCLE 86 ON FREE INFORMATION CARD 21 New Products ANALOG/DIGITAL STOR- AGE SCOPES. Besides real- time sampling speeds of up to 250 MS/s, and analog and digital bandwidtbs of up to TOO MHz, two anaiog/digital storage oscilloscopes from John Fluke provide micro- processor-calculated mea- surements. The 60-MHz, 250-MS/s PM 3355 and the 100-MHz, 250-MS/s PM 3375 (pictured) DSO's are also designed for ease of use, with such features as cur- sors and full autoset. The PM 3375 uses re- petitive sampling for ac- quisition of recurrent sig- nals of up to 100 MHz, and has 100-MHz analog band- width and 150-MHz trigger- ing bandwidth. The PM3355 has 60-MHz analog band- width and 100-MHz trigger- ing bandwidth. Both units provide 250-MS/s real-time sampling for signals to 25 MHz at 10 samples per sec- ond, four 4K memories for high-resolution acquisition and storage of digital sig- nals, and post-trigger ca- pability of up to 5,000 divisions. Otherfeatures in- clude averaging for im- CIRCLE 25 ON FREE INFORMATION CARD proved noise suppression and greater accuracy, digi- tally delayed timebase for in-depth signal examination while troubleshooting, 8-bit vertical resolution, and an envelope mode to track sig- nal variations over time. Signal analysis is sim- plified with cursor facilities that allow instant, on- screen measurement with numeric readouts of mea- sured and calculated values, automatically compensat- ing for the probes in use. The autoset feature gives au- tomatic channel selection and setting of amplitude, timebase, and triggering for any input signal. To ensure repeatability and efficiency in routine measurements, INFRARED-DETECTOR PEN. Technicians in the consum- er-electronics repair indus- try will appreciate the B.I.R.D., a battery-operated infrared-detector pen from Parts Express. The device in- stantly confirms operation of infrared-emitting prod- (a ucts, such as remote con- y trols, VCR tape-stop cir- O- cuits, and alarm-system in- j£ frared detectors. The ^ B.I.R.D.'sslim design makes jjj easy work of reaching IR O emitters on crowded VCR 5 boards. An LED conve- ne niently placed in the top of CIRCLE 2& ON FREE INFORMATION CARD the pen is there to indicate the presence of infrared light in normal light condi- tions. The B.I.R.D. infrared de- tector pen costs $55.00. — Parts Express International, Inc., 340 East First Street, Dayton, OH 45402; Tel. 800-338-0531. 64 front-panel settings can be stored. The front panel on each scope also gives clear information on the sensitivity of both channels as well as timebase and trig- ger setting, memory status, and a display magnification indicator. Optional RS-232 and GPIB/IEEE-488 inter- faces allow the DSO's to be operated under computer control or in automatic mea- suring systems. The PM 3355 has a list price under $4500.00; the list price of the PM 1375 is $5390.00. The factory-in- stalled interface options cost $500.00 each.— John Fluke Mfg. Co., Inc., P.O. Box 9090, Everett, WA 98206; Tel. 800-443-5853. MAG, IV MAG, and 2V MAG simplify signal evaluation and measurements, A x5 vertical-gain magnifier con- tributes to high-resolution differential phase and gain measurements in the R-Y mode. Chroma and IRE fil- ters can be inserted on a full-time or line-shared basis, and the selected vid- eo source is sent to a pic- ture-monitor output for observation on a color monitor. A switching-mode power supply automatically adapts the unit to a wide range of AC and DC volt- WAVEFORM MONITOR/ VECTORSCOPE. Designed with the user's needs in mind, Leader Instruments' model 5872 combination waveform monitor and vec- torscope is loaded with fea- tures that accommodate video-signal monitoring easily and effectively. It of- fers simultaneous vector and waveform display and dual-channel display for ob- servation of two video sources on the same screen. Sweep rates of 1H,2H,1V, and 2V; and 1H MAG, 2H CIRCLE 27 ON FREE INFORMATION CARD ages. The instrument is housed in a metal cabinet with a handle and feet for bench use; the cabinet can be removed for rack mount- ing purposes. The model 5872 combina- tion waveform monitor/vec- torscope costs $3,795.00, — Leader Instruments Corpora- tion, 380 Oser Avenue, Hauppauge, NY 11788. MAGNETIC SENSING PRO- BE. By sensing the presence of magnetic fields, the Lil Devil Mag-Probe from HMC lets you test any electrical/ electronic device for cur- rent-on/-otf or glitches — and doesn't require in- depth training, scbematics, or complicated hookups. The device makes it easy to accurately and safely identi- fy and separate electrical from mechanical problems. The Lil Devil detects re- 22 CIRCLE 28 ON FREE INFORMATION CARD sidual magnetism and tran- sient current pulses {"glit- ches") as fast as 10 millise- conds, and identifies north and south poles in AC- and DC-powered solenoids, re- lays, and any other devices that use a coil. When the in- strument's probe tip is placed close to the coil in the device under test, the LED in the probe's handle lights if the device is ener- gized. If the LED doesn't light, the device is de-ener- gized. The probe works without having to make a di- rect electrical connection, unlike an oscilloscope or voltmeter. Two models are available. The standard-sensitivity model tests large and stan- dard-sized solenoids and relays. The high-sensitivity model tests the full range of devices, from sub miniature to the largest, including most reed relays. The standard- and high- sensitivity Lit Devil Mag- Probes have suggested re- tail prices of $28.50 and $33.75, respectively.— HUB Material Company, P.O. Box 526, Canton, MA 02021. DISKETTE I.D. SYSTEM. A computer-disk identifica- tion system, the ReMark- Able Label Ssytem from Weber & Sons, eliminates the build-up of layers of la- bels on 5 1 /4- and 3^-inch floppydisks. Special marker pens are used to write on a thin, self-adhesive, plastic surface affixed to the disk. As the data on the disk changes, old I.D. informa- tion is simply wiped off and updated notes can be add- ed to reflect the changes. Ink removal doesn't require the use of any chemicals, al- cohol, or erasers; ink is re- moved simply by wiping the surface with a dry tissue. The ReMarkAble Label System Kit Is available as the RLS-200, with 200 self-adhe- sive writing surfaces, or as the RLS-100, with 100 writing surfaces. Each kit also con- tains one marker pen and instructions. The RLS-200 and RLS-100 kits cost $39.95 and $24.95, CIRCLE 29 ON FREE INFORMATION CARD respectively, including ship- ping. — Weber & Sons, Inc., ReMarkAble Label Systems Division, 3468 Highway 9, Freehold, NJ 07728; Tel 800-225-0044. SPECTRUM ANALYZER/LAP- TOP. For true convenience and portability, Rapid Sys- tem's R355 combination FFT spectrum analyzer and digi- tal scope includes the ver- satile Toshiba 3200 SX, a 386 laptop personal computer. The complete system allows the user to view both the input signal and its frequen- cy spectrum in real time on the computer. A two-chan- nel, 12-bit, 267-K data buff- er; 500-MHz bandwidth; and 1-MHz sampling rate are standard features in this turnkey, stand-alone testing system. The 16-MHz, 40-B laptop features an IBM-VGA-com- patible high-resolution gas- plasma display. The com- bined system offers two channels of simultaneous 1- MHz acquisition with 32-KB Cut Your Video Servicing Time By 54% With the Market Proven VA62 Universal Video Analyzing System. Today's VCRs, TVs, and MTS Stereo TVs require a proven method to quickly isolate the defective component. New technology has made simple problem solving a time-consuming and expensive procedure. A survey of over 1 500 Video Analyzer owners has shown that the 'A62's unique signal substitution method has reduced their vide i servicing time by an average of 54%, and increased their ser Icing profits. You can join the successful service centers that have cut their video servicing time and increased their profits with the VA62 Universal Video Analyzing System. Call tor a brochure on the VA62. Call 1-800-SENCORE and increase your profits. In Canada also call 1-800-SENCORE. R\ 3200 Sencore Drive. Sioux Falls, SD 57107 100% American Matte CIRCLE 177 ON FREE INFORMATION CARD O I o 23 Get A Complete Course In ELECTRONIC ENGINEERING 8 volumes, over 2000 pages, including all necessary math and physics. 29 examinations to help you gauge your personal pro- gress. A truly great learning experience. Prepare now to take advan- tage of the growing demand for people aPle to work at the engin- eering level, Ask for our brochure giving complete details of content. Use your free information card num- Per, or write us directly. $99.95, Postage Included. Satisfaction guaranteed or money refunded. rvvA/ ¥ v_ Banner Technical Books, Inc. 1203 Grant Ave, Rockford, IL 61103 CIRCLE 67 ON FREE INFORMATION CARD Try the Electronics bulletin board system (RE-BBS) 516-293-2283 The mure you use it the more useful it becomes. We support 300 anit 1200 baud operation. Parameters: 8N1 {8 data bits, no parity, 1 stop bit) or 7E1 (7 data hits, even parity, 1 stop bill. Add yourself to our user tiles to Increase your access. Communicate with other R-E readers. Leave your comments on R-E with the SYS0P. RE-BBS 516-293-2283 NOISE REDUCTION FOR UNDER $10. to'*. S M7VH£S MICROPHONE CONNECTORS & J* pK s OtAMOUN R-2 PATCHBAYS FADERS, POTS T£ fiMlH AL STFi/pq **«£* CRAMOLIN ***,, f/A/ 4£i g z o rx F o UJ O D < rr 24 Even the finest equipment in the world cannot guarantee noise-tree operation. One "dirty 11 connection anywhere in the electrical path can cause unwanted noise or signal loss. "MORE THAN A CONTACT CLEANER" CRAMOLIN ' is a fast-acting, ami-oxidizing lubricant that cleans and preserves all metal surfaces, including gold. When applied to metal contacts and connectors. CRAMOLIN"' removes resistive oxides as it forms a protective molecular layer that adheres to the metal surfaces and maintains maximum electrical conductivity. CRAMOLIN* - USED BY THOSE WHO DEMAND THE BEST: Bell * mom hi HwrifiO Ptcfcard MCKSorty} Nafcimichi Boning Jonn Flute Mis, Motorola RCA Capitol Hoards Mclntmn Lib* NASA Swvtchcrart SINCE 1 955 cAi&nnzsnEEEEiEE M7&Q Industrial Ays.. (P.O. Box J) - EKond-do, CA B2QZ5-0051 U.S.A. 1619) 743-7) 13 CIRCLE 30 ON FREE INFORMATION CARD data buffers per channel, 1024-point FFT displayed at a rate of 10 per second, and 10 mV to 50 V per division with user-selectable gain scaling. The menu-driven software and features such as save (autosave) and retrieve data to/from disk make the sys- tem easy to use. Spectra can be stored either as magni- tude or com pies data. The R355B200 SX com- bination spectrum analyzer and laptop PC costs $8495.— Rapid Systems, Inc., 433 North 34th Street, Seat- tle, WA 98103. WIRE STRIPPER. Incorporat- ing a wire stop, a front feed for close-in work, and a wire cutter, Paladin's PA 1115 Mini-Stripax meets all the hobbyist's wire-stripping and -cutting needs. De- signed to strip and cut 30- to 16-gauge solid and stranded wires in a single motion, the tool completely removes the insulation from multiple conductors without touch- ing or nicking the internal wires. CIRCLE 31 ON FREE INFORMATION CARD The lightweight and economically designed miniature wire stripper fits into spaces too small for other stripping tools and cuts precisely with minimal force. Its stainless-steel laminated blades are rated for up to 20,000 strips, and fiberglass-reinforced nylon construction makes it ex- ceptionally rugged. The Mini-Stripax is insulated to 600 volts to protect users from accidental contact with live wires. The PA 1115 Mini-Stripax wire stripper has a sug- gested retail price of 552.95.— Paladin Corpora- tion, 3543 Old Conejo Road, Suite102, Newbury Park, CA 91320. AM STEREO-FM STEREO ANALYZER. Using a pat- ented method of generating modulated RF signals, Sencore's SG80 is the indus- try's first totally integrated, microprocessor-controlled, 1EEE-488- and RS-232-com- patible AM-stereo (C- CIRCLE 32 ON FREE INFORMATION CARD QUAM) and FM-stereo (MPX) analyzer. The digitally accurate instrument pro- duces virtually noise- and harmonic-distortion-free RF, IF, and audio signals. The SC80 analyzer allows manufacturers and ser- vicemen to thoroughly per- formance-test and trou- bleshoot AM-stereo/FM- stereo receivers for param- eters such as sensitivity, se- lectivity, separation, and pilot threshold. The unit's innovative design includes RF, IF, C-QUAM, MPX, SCA, audio, tunable sweep, and marker generators. Special drive capability allows in- circuit troubleshooting, which highly accurate at- tenuator and impedance matching for 50-, 75-, and 300-ohm receiver inputs. The SC80 AM-stereo/FM- stereo analyzer — including test leads, manual, sim- plified operating guide, and "100% Made Right" lifetime guarantee — costs $3995. — Sencore, Inc., 3200 Sencore Drive, Sioux Falls, SD, 57107; Tel. 1-800-SENCORE. CIRCLE 50 ON FREE INFORMATION CARD RADIO FACSIMILE TERMI- NAL. ACE Communications' WX-1000 is a stand-alone ra- dio facsimile termina! de- signed to produce hard- copy images from various radio facsimile services — in- cluding NOAA weather charts, NFAX, and press CIRCLE 33 ON FREE INFORMATION CARD photos. The unit can even receive satellite weather pictures from NOAA, GOES, and METEOR. The WX-1000 requires only au- dio output from a short- wave receiver or an S-band receiver capable of receiv- ing facsimile signals. The built-in high-resolution, 24- pin thermal printer pro- duces clear, crisp images. It also has the capability to produce gray scale, which is ideal for Automatic Picture Transmission (ATP) by weather satellite. The WX-1000 radio-fac- simile terminal has a sug- gested retail price of $845.00.— ACE Communica- tions, Inc., 22511 Aspan Street, El Toro, CA 92630-6321; Tel. 800-523-6366. SOIC CLIP ADAPTERS. Six SOIC clip adapters, de- signed to provide test points for high-density, sur- face-mounted Small-Out- line /ntegrated Circuits (SOIQ, are being offered as kit 5514 from Pomona Elec- tronics. The kit includes one each of the 8-, 14-, 16-, 20-, 24-, and 28-pin SOIC clips, all housed in a sturdy plastic case that is fitted with a contou red-foam inte- rior to separate the en- closed adapters. The SOIC- clip test adapters securely hold both wide- and nar- CIRCLE 34 ON FREE INFORMATION CARD row-body SOIC's. Access pins are 0.025-inch-square gold-plated pins on 0.100 centers, and SOIC contacts are also gold plated. The model 5574 SOIC clip adapter kit costs $54.50. — ITT Pomona Electronics, 1500 East Ninth Street, Pomona, CA 91766. SOLDERING IRONS. De- signed for soldering large components, two soldering irons from M. M. Newman feature oversize heating el- ements and tips to provide greater thermal inertia. Antex C5 and XS soldering irons have 0.178-inch diame- ter heating elements and big, iron-plated copper tips. They both feature remova- ble finger supports. With its heating element located directly under its tip for optimum thermal effi- ciency, the 17-watt CS is as powerful as a conventional 35-watt iron. The 25-watt model XS is comparable to a standard 40-watt iron. The Antex CS and Anfex XS soldering irons have sug- gested list prices of $18.95 and $21.95, respectively. — CIRCLE 35 ON FREE INFORMATION CARD M. M. Newman Corporation, 24 Tioga Way, P.O. Box 615, Marbiehead, MA 01945. R-E Train at Home to be an Electronics Technician ! Professional training and equipment can help you qualify for a dynamic, high-paying career in your spare time. As the demand for computers and micro- processors in business and manufacturing continues to grow, so does the need for qualified technicians. It's not unusual for ex- perienced technicians to earn from S3 5, 000 to more than $40,000 a year.* Now there's a way you can train for this exciting field without interrupting your job or home life. Choose From These Prog rams of Study •Electronics & Microprocessor Technology •Industrial Electronics & Microprocessor Technology •Computer Servicing & Electronics Technology •Specialized Associate Degree In Electronics Technology You Get Professional Equipment For Professional Training Depending on the program you select, you'll perfect your skills using this advanced equip- ment, included in the price of tuition: (■ Soyr«: U.S. Bufcwi of Labor SutHiici) • Zenith Data Systems eaZy Personal Computer • Digital Multimeter • Digital Logic Probe • Elenco Oscilloscope Exclusive Extras That Enhance Your Training Feoples College introduces some training firsts to make your learning experience more complete; •Accelerated Learning System — a scien- tifically proven study system that lets you learn faster and easier than ever before, •Optional One-Week Seminar — available with our advanced programs. Conducted on our campus near Orlando, Fla. Not required for graduation, but a valuable opportunity to fine tune your skills with personal guidance. •Video Tutor Training Tapes — give you a permanent, visual record of informative lee tu res and close-up demonstrations. •Experience Labs — professionally designed experiments that give you hands- on "bench" experience. •Industry Cenification Training Guide — provided with three of our programs. Gives you first-hand insight into the examination you may take for your professional license. For COLOR CATALOG Mail Coupon or Call TOLL FREE 1-800-366-3113 No Obligation. No sates person will calJ. Our programs are accredited by the Accrediting Commission of the National Home Study Council YES! I would like to know more about your training programs. Send a catalog to: Name Address City State 5 _Zip_ Peoples College OF INDEPENDENT STUDIES 233 Academy Drive • P.O. Box 421768 Kissimmee, FL 34742-1768 I MmiiI'.; . !.'.'.[.. Peoples i -i ..mi: > o X CD CO o 25 w o z o rr 111 6 D < DC Managing to iGef Ahead\ Test yourself with this sample question: Which one of the following questions may you ask a prospective employee in a job interview? (1) Do you own or rent your home? (2) Are you married? (3) Are you able to work overtime? (4) Have you ever been arrested? (5) All of the above? Now wouldn't you like to test yourself against the real thing? If you've got the experience and knowledge it takes to get the job done, you can get certified in professional service management. The Certified Service Manager exam is offered through NESDA for owners or service managers with a minimum of 4 years of experience. For a practice test and more information about CSM Certification, write to NESDA, 2708 W. Berry St., Fort Worth, TX 76109-2356, or phone (817) 921-9061. f E (t laansm*) CABLE - TV SIGNAL REH€VER§ ■FOR ELIMINATION OF SEVERE INTERFERENCE -FOR "CENSORING' OF ADULT BROADCASTS ^V ■#1.^ ■ ATTENUATION - 45 dB TYPICAL ■ BANDWIDTH - 4 MHz AT 5 dB POINTS ■ INSERTION LOSS - 2 dB MODEL TUNING HAN BE FOH CHANNELS PAS5BAND ppjce SHIPPING 23 H 50-GSMHz 2 3 tar 6 meter ham 50-300 MHl m 46FM 66-103MHJ 4.5,6 (or any FM1 50-300 WHl san SHIPPING 1417 120-144 MHz I4M1 15(B) 16(C) 17|D) 50-400 MHz W Of C.O.D. CHARGES 1822 144-174MHZ 10(E) 19(F) 20(G) 21(H) 22 (1) 50-400 MHz S30 713 174 -216MHz 7.8.9.10.11.12.13 50-400 MHz $30 3 for $75 - 1 for $200 - mix or match CALL TOLL PRE E FOR CO. D . OR SEN D CHEC K TO ORDER FAST DELIVERY 30 DAY MONEY BACK GUARANTEE (3 FILTER LIMIT) Star Circuits P. O. Box 94917 Las Vegas, NV 89193-4917 1-800-433-6319 N ew Lit SK CROSS-REFERENCE GUIDE. Thomson Consum- er Electronics' SK Replace- ment Semiconductor number Guide (SKG202F) contains more than 3370 parts, including 228 recently introduced semiconduc- tors. Its 329-page cross-ref- erence section contains references to more than 217,000 original devices. yi^ CIRCLE 36 ON FREE INFORMATION CARD The SK devices cover a wide variety of both discrete components and integrated circuits with consumer as well as industrial applica- tions. The guide contains expanded specifications in the discrete devices charts. Included in the SK line are thyristors, rectifiers, op- toelectronics, micro- processors, and many other types of devices, all under warranty for one year. The SK Replacement Sem- iconductor Guide (SKG202F) is available from Thomson distributors na- tionwide. — Thomson Con- sumer Electronics, Dis- tributor and Special Prod- ucts, 2000 Clements Bridge Road, Deptford, NJ 08096-2088. DATA ACQUISITION AND CONTROL. Volume 21 of MetraByte's product hand- book includes comprehen- sive data on the company's complete line of data-ac- quisition, industrial-control and -monitoring, video- imaging, signal-con- ditioning, personal-instru- CIRCLE 37 ON FREE INFORMATION CARD mentation, and communi- cations products for IBM PC/XT/AT, PS/2, and Apple Macintosh II microcomput- ers. The 304-page color handbook features com- plete technical data on MetraByte's brand new WORKHORSE line of high- speed industrial-control and -monitoring products. Also included are the PCIP- SCOPE, a single-board digi- tal-sampling oscilloscope; the DAS-HRES, a 16-bit data- acquisition board; the VOS/ DVOS software, an Icon- based user interface for MetraByte's image-process- ing hardware; and the MBIC family of19-inch rack- mounted IBM-compatible industrial computers. Prod- uct characteristics are pre- sented in easy-to-use quick- selection guides, followed by complete technical and pricing information. The Volume 21 catalog is available at no charge. — MetraByte Corp., 440 Myles Standish Blvd., Taunton, MA 02780. R-E 26 Discover Your Career Potential In The Fast Growing Field Of High-Tech Electronics! CIE Gives You The Training You Need to Succeed... At Your Own Pace...& In Your Own Home! If you're anxious to get ahead ...and build a teal career... you owe it to yourself to find out about the Cleveland Institute of Electronics! CIE can help you discover your career potential in the fast growing field of high-tech electronics. A career that will challenge and excite you every day... reward you with a powerful feeling of personal accomplishment... and deliver a level of financial security you may have only dreamed of before! As the leading school in home-study electronics. CIE has helped over 150,000 students in the U.S.A. and over 70 foreign countries get started in this exciting field. To find out how CIE could be helping you... read on... then send for a CIE catalog TODAY! A Growing Need For Trained Professionals! The career opportunities shown here are only a few of the challenging, high- paying careers you could enjoy as an electronics technician. You could be the "brains" behind the scenes of an exciting TV broadcast... trouble-shoot life-saving medical equip- ment... design exotic new aeronautics systems... CI Es job-oriented programs offer you the quickest possible path to the career of your dreams! And CIE also features military and union re-training, to build on what you already know. Dozens Of Fascinating Careers To Choose From! Even if you aren't sure which career is best for you, CIE can get you started with core lessons applicable to alt areas of electronics. As you advance, CIE makes job opportunities available to you through the bimonthly school paper, The Electron f 7^~ Data Communications it f? "' M ' r~i' W Automotive Electronics ■ Trl : i u Computer-Assisted Manufacturing Consumer Electronics Military Electronics Personal Training From A Renowned Faculty, Unlike the impersonal approach of large class- room study, CIE offers you one-on-one instructional help 6 days a week, toll-free. Each CIE lesson is authored by an independent specialist, backed by CIE instructors who work directly with you to answer your questions and provide technical assis- ti ed - tance wnen vou nee ^ ''■ World Headquarters Practical Training... At Your Own Pace. Through CIE, you can train for your new career while you keep your pres- ent job. Each course allows a gener- ous completion time, and there are no limitations on how fast you can study. Should you already have some electronics experience, CIE offers several courses which start at the intermediate level. "State-Of-The-Art" Facilities & Equipment, In 1969, CIE pioneered the first elec- tronics laboratory course, and in 1984, the first Microprocessor Laboratory. Today, no other home study school can match CIE's state-of-the-art equipment. And all your laboratory equipment is included in your tuition cost. There is no extra charge — it's yours to use while you study at home and on the job after you complete your course! Earn Your Degree To Become A Professional In Electronics! Every CIE course you take earns you credit towards the completion of your Associate in Applied Science Degree, so you can work towards your degree in stages. And CIE is the only school that awards you for fast study, which can save you thousands of dollars in obtaining the same electronics education found in four-year Bachelor's Degree programs! Write for details today! Send For Your Catalog Today! Cleveland Institute of Electronics, Inc. 1776 East 17th St., Cleveland, Ohio 44114 ARE-163 □ YES! Please send me your independent study catalog (For your convenience, CIE will have a representative contact you— there is no obligation.) Apt! Area Code/PhonE Wo. Bill bulletin on educational benefits: □ Veteran n Active Duty Mail This Coupon Today! > X> O X 29 Electronics KfOOD^M) FREE CATALOG OF HARD-TO-FIND TOOLS is packed with more than 2000 quality items. Your single source for precision tools used by electronic technicians, engi- neers, instrument mechanics, schools, labo- ratories and government agencies. Also contains Jensen's line of more than 40 tool kits. Send for your free copy today! JENSEN TOOLS INC., 7815 46th St., Phoenix, AZ 85044. (602) 968-6231. CIRCLE 115 ON FREE INFORMATION CARD AMAZING POCKET REFerence.: 480 pages of tables, formulas, constants, con- versions and maps and it fits in your shirt pocket! (3.2" x 5.4" x 0.6") Chapters include Electronics, Computers, Math, Tools, Glues & Solvents, Chemistry & Physics, Con- struction, Carpentry, Geology, Hardware, Au- tomotive, Air, Water, Welding, Plumbing, Pipe, 1-800 Airlines, Area Codes, Money, and much, much more. $9.95 + $2.00 shipping (Colorado inc. 56c tax). Check/Visa/ MC. Se- quoia Publishing, Inc., Dept. 953, P.O. Box 620820, Littleton, CO 80162. CIRCLE 183 ON FREE INFORMATION CARD GET YOUR RECHARGE CATALOG FREE...EARN BIG $$ IN YOUR SPARE TIME — All supplies and Do-lt-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, 62 N Coleman Rd., Cen- tereach, NY 11720, 516-736-7977, 800-221-3516, Fax: 516-732-4650 CIRCLE 192 ON FREE INFORMATION CARD NEW 1990 GENERAL CATALOG OF TOOLS & TEST INSTRUMENTS is now available at no charge. 148 color-coded pages make this source book of products for testing, repairing and assembling electronic equipment easier than ever to use. Each product line has been expanded to include over 100 new products. With color photos, descriptions and discounted pricing, it fea- tures test equipment, precision hand tools, tool kits, soldering supplies, static control products and more. CONTACT EAST, 335 Willow St., North Andover, MA 01845 (508) 682-2000. CIRCLE 55 ON FREE INFORMATION CARD THE MODEL WTT-20 IS ONLY THE SIZE OF A DIME, yet transmits both sides of a tele- phone conversation to any FM radio with crystal clarity. Telephone line powered - never needs a battery! Up to 'A mile range. Adjusta- ble from 70-130 MHZ. Complete kit $29.95 + $1.50 S f H. Free Shipping on 2 or more! COD add $4. Call or send VISA. MC. MO. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 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. SIMPLY SNAP THE WAT-50 MINIATURE FM TRANSMITTER on top of a 9v battery and hear every sound in an entire house up to 1 mile away! Adjustable from 70-130 MHZ. Use with any FM radio. Complete kit $29.95 + $1.50 S + H Free shipping on 2 or more! COD add $4. Call or send VISA, MC, MO. DECO INDUSTRIES, Box 607, Bedford Hills, NY 10507. (914) 232-3878. CIRCLE 127 ON FREE INFORMATION CARD CABLE TV CONVERTERS AND DE- SCRAMBLERS SB-3 $79.00 TRI-BI $95.00 MLD-$85.00 M35B $89.00 JRX-DIC $129.00 Special combos available. We ship COD. Quantity discounts. Call for pricing on other products. Dealers wanted. FREE CATALOG. We stand behind our products where others fail. One year warranty. ACE PRODUCTS. P.O. Box 582, Saco, ME 04072 1 (600) 234-0726. CIRCLE 75 ON FREE INFORMATION CARD APPLIANCE REPAIR HANDBOOKS— 13 volumes by service experts: easy-to- understand diagrams, illustrations. For major appliances (air conditioners, refrigerators, washers, dryers, microwaves, etc.), elec. housewares, personal-care appliances. Basics of solid state, setting up shop, test instruments. $2.65 to $7.90 each. Free brochure. APPLIANCE SERVICE, P.O. Box 769, Lombard, IL 60148. (312) 932-9550. CIRCLE 84 ON FREE INFORMATION CARD o K^™m universal Laboratory \power \SUPPL Y This universal power supply offers high performance and flexibility at low cost. REINHARD METZ WHILE NUMEROUS BENCH POWER SUPPLIES have emerged over the years, few combine the performance, flexibility, and low cost of the version described here. This article describes a well- regulated, modular, lab- grade power supply with dual 0-50- volt. 0-5-amp DC supplies, and a single 5-volt, 3- amp DC supply. It uses two identical custom PC boards, one for each 50- volt supply. There's also a customized heat sink with space for both PC boards that minimizes point-to-point wiring in the 50- volt supplies. How- ever, because of the modular design, you can customize the configuration as needed. See Table I for a perfor- mance summary. Circuit description Figure 1 is the schematic of the power supply. The value of the design lies in the use of IC1 , an LM317HVK adjustable series-pass voltage reg- ulator, for broad-range performance. The "HVK" suffix specifies the high- voltage version of the regulator. The remainder supplies voltage-setting and current-limiting func- tions. The input to to IC1 comes from the output of BRI, which is filtered by CI and C2 to about +60 -volts DC, and the input for current-sense com- parator IC2 comes from BR2. which also acts as a negative bias supply for regulation down to ground. The purpose of IC1 is to maintain the out terminal at 1.25- volts DC above the adj terminal. The current drain at the adj terminal is very low (nominally 25 p.A) and, as a result, RI5 and R16 (the coarse and fine volt- age adjustments) and R8 form a volt- age divider, with 1.25 volts appearing across RS. The bottom end of R16 connects to a — l.3-volt reference level generated by D7 and D8, letting the R8-R15 divider set the output volt- age all the way down to ground when R15 + R16 = ohms. In general, the output voltage is determined by: (V OUT - 1.25 + 1.3)/ (R15 + R16) = 1.25/R8. Thus, the maximum value from each variable supply board is: TABLE 1— PERFORMANCE SUMMARY Characteristic Capability Number of supplies 2 (fully floating) Voltage range 0—50 VDC Current range 0—5 A Coarse vs. fine control ratio (both current and voltage) "■ Voltage regulation 0.01% line, 0.1% toad Current limiter 0.5% OUT" (1.25/ R8)X(R15 + R16) = 50.18 volts DC. Using potentiometers R15 and R16 NOTE: (a) There's a current- limiting LED; (b) Has internal + 5 VDC, 0—3 A supply. to control the voltage, V ol]T ranges from 0-50 volts DC. As current de- mand increases, the drop across R2 increases, and at about 0.65 volts (which corresponds to about 20 mA), Ql and Q2 turn on, becoming the main current path. Also, R3 and R4 ensure that Ql and Q2 share the load equally. Current limiting is provided by IC2. Its nonin verting input uses the output voltage as a reference, and its inverting input is connected to the > do o _L 10 (D O 31 « RADIO-ELECTRONICS voltage divider created by R6 and cur- rent-limit potentiometers R 1 3 and R14. The drop across R6 is about 1.25 volts, the reference voltage mentioned above as being the difference between the out and adj terminals of IC1. Cur- rent from Ql and Q2 flows through R9, creating a drop across R13 + R14. Thus, IC2 trips when the drop across R9 creates current through R13 and R14, causing the voitage at the non- inverting input to exceed V OUT . That sets the current limit point at: (I OUT x 0,2)/(Rl3 + R14) = 1.25/ 100K; I OUT = 0-5 amps. Thai corre- sponds to a range of about 0-5 amps. At the current limit point, lC2's out- put goes low, pulling the adj lead down via D2 and lighting LED I. Ad- ditional current for D5 is provided by R5. As the adj lead is pulled low, the output follows, until the output cur- rent drops to a level corresponding to the setting of R 13 and R 14. Since the output voltage can be anywhere from 0-50 volts, the power supply for 1C2 must track that range using D3, D4, and Q3. Next, D9 en- sures that the output voltage doesn't rise when the supply is shut off, while D10 protects against supply back- feeding. Finally, Ml monitors voltage and M2 monitors current. The power supply is modular; each PC board is used for one 50-volt supply, and in- cludes all parts other than those for the front panel and the 5- volt supply. Since a dual 50-volt version may be popular, Tl accomodates two supplies and the 5-volt supply, and a custom heat sink for the two PC boards is available. Construction The transformer is mounted on a 6- x 5- x 1-inch L-bracket in the cen- ter of the supply, and the heatsinks for IC1 and BR1 go on the back of the transformer bracket. A 6- X 8- X 6- X 1 1 -inch U-shaped cover of '/ifi-inch aluminum completes the assembly. Complete all drilling and preparation before assembly, but in- stall only the transformer and its bracket for now, to make wiring easier for you. Next, assemble the PC board! s) for the 50-volt supplies; Rg. 3 shows the parts placement diagram. Install all components except Ql, Q2. and ICl. Check resistor values as you go. and mount the heat sink for BR I before installation. Don't foraet to observe 23,5 ,„ 7 ' a ,7 ill -H TT 9 6.5 Ql MJ15Q23 ICl LMH7HVK —k i" 02 MJ15023 ®— I I I =T+ J 1-0 8-»- »14i* ^-14-^| -64' *-17-H — 2T itt.5- ~ W J -25 EDGE OF HEAT SINK FIG. 2— POWER SUPPLY HEAT SINK LAYOUT. All marked dimensions are in millimeters, all mounting holes are Winch in diameter, all lead holes are 3 /is-inch in diameter, and add 3 mm to all dimensions with an ( ' ) to align the PC boards. T1 (RED/YELI ' 42 >VAC '(REEVYEU IBUJ/YELI (BW/YELI ft BR2 t"^4-02 , Ol -U D7f i R?i i^lDBii C9 i- R | 19 - J20- FIG. 3— PARTS PLACEMENT DIAGRAM FOR 50-volt supply. Only one primary and the two relevant secondaries of T1 have been depicted, lor brevity. FIG. 4— PROTOTYPE OF THE POWER SUPPLY. Note the custom PC board heatsink at right, and how S1, F1, LMP1, and R21 are wired. polarities on all the electrolytic capac- itors. Use the alignment holes with 6-32 screws for the PC board(s). In- stall Ql. Q2, and ICl, using mica insulators, heat sink compound, and 6-32 screws. Check for shorts from 3 n x CO SO O 33 All resistors are %-watl, 5%, un- less otherwise indicated. R1— 5000 ohms, 1-watt R2— 33 ohms R3, R4— 0.1, 3-watt R5— 680 ohms R6— 11 5, 000 ohms, 1% R7— 220 ohms R8— 274 ohms, 1% R9— 0.2 ohm, 5-watt R1 0—24,000 ohms R11— 360 ohms R12— 2400 ohms R13-— 100,000-ohm potentiometer R14, R15— 10,000-ohrn potentiometer R16 — 1000-ohm potentiometer R17— 20,000-ohm PC-board- mounted potentiometer R18— 500-ohm PC-board-mounted potentiometer R19— 470,000 ohms R20— 5000-ohm PC-board-mounted potentiometer R21 — thermistor in-rush protector (Keystone KC003L) Capacitors CI, C2— 4700 m-R 100 volts (Pan- asonic P6430) C3— 1000 (jlF, 50 volts, Panasonic P6272 C4— 1 up 63 volts C5— 10 (tF, 500 volts C6 — 0.001 n-F, ceramic disc C7— 100 pF, mica C8, C9— 10 (iF. 50 volts C1 0—22,000 p.F, 16 volts (Panasonic P6420) C11, C12— 0,1 u.F, ceramic disc PARTS LIST Semiconductors IC1— LM317HVK adjustable, series- pass, high-voltage regulator IC2— LF357A JFET input, 8-pin DIP comparator IC3— LM323K 5-volt DC regulator in TO-3 case D1, D2, D7, D8, D9— 1N4148 ger- manium diode D3, D4— 1N4744A, 15-volt, 1-watt Zener diode D6— 1N4736A, 6.8-volt, 1-watt Zener diode D10— FR802 8-amp, 100-volt fast-re- covery silicon rectifier (TO-220 package) BR1, BR3— MB102 10-amp, 200-volt bridge rectifier BR2— DB103 1-amp, 200-volt bridge fp^t i f i p r Q1 , Q2— MJ5023 or ECG68 PNP sil- icon transistor Q3— ECG128 or 2N3700 1 watt gen- eral purpose NPN silicon transistor LED1— yellow light-emitting diode Other components F1 — 8-amp fast- blow fuse F2 — 6-amp fast-blow fuse T1— 600 VA transformer: 120-volt AC primary; two 42 -volt, 5-amp sec- ondaries: two 17-volt, 250-mA sec- ondaries; and one 7-volt, 3-amp secondary PL1— 120-volt AC pilot light M1 — 50 mA meter (GC Electronics 20-1110) M2— 100 (iA meter (Jewell 81T) S1— 120-volt, 10-amp DPST switch S2— SPDT switch J1, J3, J5 — red banana jack J2, J4, J6— black banana jack Miscellaneous: 8-inch wide x 6-inch high x 11-inch deep aluminum case with Vs-inch predrilled aluminum plate as front panel (including holes for handles) and 8- x 1 1 - x %2-inch steel plate with a 1-inch lip on the bottom, two front-panel-mounted case handles, 6- x 8- x 3- Vis-inch dual-supply main heatsink, heat- sink for 5-volt DC regulator with TO-3 case, heat sink for BR1, 3- wire power cord, knobs, four rubber feet, panel-mounted fuse holder (for F1), two PC-board mounted fuse clips (for F2), PC board (Digi- Key #F040}, three TO-3 transistor insulator kits, silicone grease, wire, solder, etc. NOTE: The following parts are available from A&T LABS, P.O. Box 552, Warrenville, IL 60555; plated PC board with parts placement silkscreen, 519.00; 600 VA custom dual-supply transformer (T1), $66.00; custom dual-supply main heatsink, S42.00; LM317HVK (IC1), S8.00; MJ4502 (Q1 and Q2), $6.00; Ml $16.00. Send check or money order, except for COD orders via UPS in the U.S. If you don't order T1, add 5% shipping and han- dling for U.S., and 10% for Cana- da. If you order T1. add 12% for U.S., and 17% for Canada; Illinois residents add 6.75% sales tax. CO o z o (Z \- o -I o < rr FIG. 5— PRIMARY HEAT SINK ASSEMBLY CLOSE UP. You can see how Q1 and IC1 are attached, the silicone grease used for heat transfer, and how the heatsink is attached to the PC boards. The mica insulators aren't clearly visible from this perspective. Ql, Q2, or IC1 to the heatsink. Note that BR1 and BR3 have different pin connections than BR2. A variety of meters can be used with this design. Sensitivity dif- ferences are compensated with PC- board- mounted resistors and potenti- ometers. The values in the parts list call for 50 p. A/2500 ohms for Ml , and 100 u.A/700 ohms for M2. In most cases, panel meters require some faceplate disassembly or removal to mark them for 50 volts and 5 amps DC at full scale. Assuming sensitivities of I v and R v for Ml and 1, and R, for M2, the resistor values are: • R19 = 25/I v , R20 = 2xR v . • R17 = 2x(l.0,-R 1 ),for5amps full-scale. • R18 = 2X(0.1/I|-R,), for 0.5 amp full-scale. • R18 = 2 x (0.2/1, - R,), for I amp full-scale. Proceed with the point-to-point wiring from the PC board to the front panel. Those wires should all termi- vantinued OH pa$e 69 34 D '21 is -^lON M A COUPLE OF DECADES AGO. RESEARCH scientists were examining how the population ratio of positive to nega- tive ions in our atmosphere affect human behavior. Many theories were generated — among them, that positive ions cause irritability and er- ratic behavior, and that negative ions promote well-being. That theory still persists, as can be seen from the nu- merous products that are marketed to flood your home or office with nega- tive ions. Because of the interest, the elec- tronics magazines of the time pub- lished articles on the properties of ions, how to produce them, and even how to build chambers to measure them. The device in one of the first articles, back in 1969, used a short detector-rod antenna in a cylindrical wire-mesh detector screen. The screen was polarized to plus or minus 60 volts DC, causing ions of the op- posite polarity to that of the screen be attracted to it, pass through, and be collected by the detector rod. A spe- cial tube was used to amplify the min- ute voltage induced in the detector rod, which had a 100,000-megohm input impedance. The device used a l.5-volt battery for the tube filament, a 9-volt battery for the circuit, and a 67 -volt battery for the screen. Circuit description The schematic of an updated ver- sion is shown in Fig. 1, The tube was replaced with a dual-gate RCA 40673 or 40841 MOSFET with both gates tied together as the detector input. The input impedance isn't as high as was the case with the tube, but there's more than enough sensitivity without needing a 100,000-megohm grid re- sistor; and the gate impedance bleeds off ions without an external resistor. Rl prevents static- voltage buildup on the detector screen in dry weather and instability in Ml. The MOSFET drain feeds a bal- anced DC bridge using two 2N2222's coupled to Ml, a zero-center, ± 1 50- p. A meter. Since the MOSFET Build this ion meter and keep track of the level of ions in your home. By PETER A. LOVELOCK ( ( ( forms one leg of a bridge, any chang' in drain current caused by ions detector will unbalance it, deflecting Ml. Since the device can indicate oniy relative negative or positive ion levels, the ion meter is balanced for zero, and reads increasing or decreas- ing levels for the selected polarity; don't interpret Ml as indicating a negative left-hand and positive right- hand scale. Besides filtering the ion type, the detector screen also shields the detector rod from static charge. If the shield is removed, body move- ments within a couple of feet of the detector rod can make Ml fluctuate, due to static charge that may be pres- ent on your clothes. The ion meter can be powered from either a 9-volt battery, Bl, or a 1 2- volt DC plug-in supply. Whichever supply is in use operates IC1, a 555 which generates a square wave that's fed to a 6-stage ladder multiplier composed of D1-D12 and C1-C14. Each stage acts as a voltage doubter, so the multiplier increases the applied voltage by 2 x 6, or 12. The +5-volt internal supply is boosted to plus or minus 60 volts at the detector screen, whereas using Bl the multiplier generates plus or minus 108 volts DC. The available current is a few microamps, and the output impedance is about 100 megohms, or Rt. Also, Rl prevents loading the multiplier, dropping the detector- screen voltage and cutting sensitivity. The voltage polarizes the detector screen, as long as there's no load. Measuring the multiplier's output voltage is difficult, since most multi- meters, despite their high input im- pedances, will load the output of the ion meter. Typically, a multimeter with 10-megohm input impedance ex- hibits a false reading of 25-45 volts DC, when using the plug-in supply. The good thing about the very high impedance at the detector is that s shorting the plus or minus 60 or 108 5 volts DC from screen to case won't 2 generate much current, so a short ^ won't damage the circuit. However, g 9 & 35 PIASTICCAP FROM A SWITCHI ¥1 y z o QC F O _J _l HI Q D < EC FIG. 1— SCHEMATIC OF THE ION METER; B5 controls the sensitivity of differential amplifier Q2-Q3, and R5 and R8 control the balance. Q1 is a very high input impedance dual-gate MOSFET, and IC1 is a 20-kHz astable feeding a x12 voltage multiplier com- posed of D1-D12 and C1-C14. Sl " « 03 C12"" R5 FIG. 2— PROTOTYPE OF THE ION METER, showing the rear internal view. The detector screen plugs into J2 and J4, and the detector rod plugs into J 3. Note that the wiring for IC2 is fairly tight, and also that the jumper running under C1 2 is supposed to be ru n on the foil side of the PC board. be very careful, regardless of the low current, when dealing with voltages of that magnitude. Switch S2 reverses the multiplier input-out- put connections, letting the detector screen voltage be either positive or negative, regardless of whether 1C2 or Bl is used as the supply. The ion meter draws 4 mA at 9- volts DC, so a standard 70 mAh, 9- volt battery should be enough to give you 16 hours of continuous use. Construction The interior view of ion-meter pro- totype is shown in Fig. 2. You can build the circuit on a 2 x 3-inch piece of perforated circuit board, or you can etch a PC board using the pattern pro- vided in PC Service. Before you use the foil pattern provided in PC Ser- vice, you may have to modify it slightly. Figure 3 points out two jum- pers that must be added, and one that must be cut. The PC-board source in cabinet 2ter c i PARTS LIST All resistors are "A-watt, 5%, less otherwise indicated. R1— 100 megohms (see text) R2-— 3300 ohms R3— 82,000 ohms R4, R1 0—22,000 ohms R5— 250-ohm, 2-watt mounted potentiometer R6, R1 2— 10,000 ohms R7— 50,000-ohm, 2-watt, cabinet mounted potentiometer R8— 1000-ohm, 15-turn, PC-board mounted, trimmer potentiometer R9, R14— 150 ohms R1 1—15,000 ohms R13— 220 ohms Capacitors C1-C14 — 0.01 fj-F, 35 vofts, disc ce ramie C15 — 470 pF, 50 volts, disc ceramic C16— 22 u.F, 16 volts, tantalum C17— 0.1 jiFj 16 volts, tantalum Semiconductors D1-D12— 1N4001 silicon diode Q1— RCA 40673 or 40841 dual-gate, P-channel MOSFET Q2— 2N2222 NPN transistor 1C1— 555 timer 1C2— 7805 5-volt DC regulator Other components S1 — miniature 3PDT switch S2— miniature SP3T switch M1— ±150-u,A meter with centered needle PL1, PL2 — threaded banana plugs and nuts J1— miniature monophonic jack J2, J4 — banana jacks without ground lugs J3— miniature pin jack Miscellaneous: Chassis box, 5-Vi x 3 x 2-Va-inches, PC board stand- off kit, TO-220-type transistor case insulated mounting kit for IC2, 120 VAC-to-12 VDC plug-in power sup- ply, 4 x 5-inch piece of Vb-inch grid metal screening, 8-pin DIP socket, two 3-pin transistor sockets, one 4- pin transistor socket. 9-vo!t battery clip, plastic cover from sub- miniature switch for detector rod, solder, wire, hardware, etc. NOTE: The RCA 40763 dual-gate MOSFET is available for $2.00 plus S3. 00 shipping and han- dling from Circuit Specialists, P.O. Box 3047, Scottsdale, AZ 85271-3047, (800) 528-1417 or (602) 966-0764; shipping time is normally about 10 days. The PC board is available from R.R. As- soc, 31066 Glendon, Los An- geles, CA 90034, for $4.50. That includes shipping and handling; California residents add sales tax. 36 FIG. 3— PARTS-PLACEMENT DIAGRAM of the ion meter. Note the terminals used for J1, and the modifications to the PC board (all they involve is cutting a foil and adding two jumpers). the Parts List will make every effort to make those changes for you in ad- vance, but be aware of them anyway. Rl may be hard to find; an alter- native is ten ¥4- or Vs-watt, 10- megohm resistors in series. Potenti- ometer R8 is a 10-15-tum, PC-board- mounted version, while R5 and R7 are the case-mounted variety, and per- mit easy adjustment of Ml . The parts- placement diagram is shown in Fig. 3. Mount the voltage multiplier first, being careful with CI-C13 and D1-D12. A mistake there can reduce detector-screen voltage, or result in no polarizing voltage at all. The resis- tance from the cathode of Dl to the anode of D12 should be about 300 ohms. Install IC! using an 8-pin DIP socket, then R2, R3, and C15. Next R4, R6, R8-R12, R15, and C16 are installed; R4, RIO and R15 are to be vertically mounted. Then, connect Ml, R5, R8, SI, S2, and the detector. Leave plenty of extra lead length; you can trim off the surplus when the PC board is installed in the case. Install 90 DEG.FOLD 2W REAR PANEL h- -zw- ■ \w- -K" (DEPENDS ON THICKNESS OF J1I 90 DEG FOLD -W- -W _ '_ /~\ W'Jt0LE_ 2W 1W METER HOLE (SEE TEXTI #6 HOLE 40— o w h-w— •+• Li \_J H0LE tOi * \^J HOLE U, j»jy 1 tl J -0 #6 HOLE 2\ t" 2V —w«-H #6 H0LEO- ! W it -\w- - 5»" H h - iw ■ TOP SURFACE FRONT PANEL BOTTOM FIG. 4— ION METER CASE LAYOUT, consisting of top surface, front panel, bottom sur- face, and rear panel. Make sure that everything has been carefully measured before any drilling or cutting. > J3 S (0 CO o 37 o z o £ 5 LU Hi 6 < IX FIG. 5— DETECTOR SCREEN, SHOWING (a> the cage with the banana clips, and (b) the cap over the top of the cage, made from a 1,25-inch inner-diameter pill bottle cap. Q1-Q3 with transistor sockets if pos- sible; otherwise, use minimal solder- ing time and, preferably, a grounded soldering iron for Ql. The case All prototype components were mounted in a two-piece, 5- 'A x 3 x 2- '/a-inch box. One half serves as front panel for R5, R7, SI, S2. and MI. The top of that half supports the de- tector rod and screen as shown in Fig. 2-«. Figure 4 is the dimensioned case layout, showing the upper surface, front panel, lower surface, and rear panel. Use a straight-edge and pencil to locate the front-panel holes for SI, S2, R5, and R7, mark with a center punch, and drill. Check the shaft di- ameter of the parts you plan to use, and adjust the drill sizes accordingly. The hole for Ml isn't dimensioned since yours may vary from that of the prototype. \ou'll need a ± 150-p.A zero-center meter for Ml. A surplus FM-radio tuning meter should work nicely. Some meters are "D" -shaped, requiring modification of the hole with a small file, for an easy fit. If yours uses mounting screws, drill ad- ditional holes, and mount Ml on the front panel with screws, clips, dou- ble-sided adhesive tape, or rubber ce- ment. Apply the latter to both the rear surface of the meter and the front pan- el, and let it dry. It'll act like contact cement, but you can still pry Ml off. Drill a #6 hole for the heatsink of IC2 in the bottom surface of the top half of the case, as shown in the lower surface drawing of Fig. 4. For a case other than the one specified in the Parts List, modify the drilling dimen- sions. You can try a plastic case if you want to, but a metal one might pro- vide better shielding. When all the holes are drilled, don't mount any components until you've applied the lettering using rub-on transfers. Clean the front panel with steel wool or rubbing alcohol. Cut the let- tering with an X-acto knife, hold with tweezers, and position on the front panel; don't mount the knobs, screws, or Ml until you're done. Press the lettering with a fingernail, run a pen over the surface, and lift the back- ing off with tweezers. Cover with pa- ing off with tweezers. Cover with pa- per, and rub firmly with a fingernail for a good bond. Let it dry for a day before applying varnish. The detector The detector screen is made from a 4 x 5-inch piece of ^s-inch metal screening, as shown in Fig. 5. Roll it into a 5-inch long cylinder, hook the ends to form a seam, and solder. Sol- der small L-brackets with #6 holes to one end, and mount banana plugs PL1 and PL2 with nuts; they plug into J2 and J4. The opposite end of the detec- tor-screen cylinder can be closed with a large plastic pill-bottle cap (1 .5-inch inner diameter). Figure 6 shows the detector-rod in- 1 I S4f H HOLE, -O- - #4 HOLE | NUUy-p. HOLE " +-H E* W l -6- #* ; l h n i f , T FABRICATE FROM GLASS-EPOXY BOARD a BOX TOP SURFACE INSULATOR BOARD PIN JACK FIG. 6— DETECTOR-ROD INSULATOR BOARD, showing (a) physical layout and (b) assembly into the case. sulator board, made from a 1.25- x I- !^t-inch piece of glass phenolic; the detector rod plugs into J3. As shown in Fig. 4-b. mark and punch the Va- inch hole for the detector-rod in- sulator board. Drill two l^-inch and two #6 holes as shown. Center the hole for J3 on the 3 /i-inch hole in the top of the case, and drill two holes in the insulator board through the mounting holes in the top of the case. Attach the insulator board to the inside of the top of the case with #4 machine screws. Make the detector rod from a 5- 5 /i6-inch piece of '/ia-inch piano wire, as shown in Fig. 4-c. Glue a rubber cap from a small sub- miniature switch handle on one end as a grip. That'll let you insert and re- cotuinuecl on page 70 38 Limit your audio volume to prevent clipping and distortion. LOWELL D. JOHNSON HAVE YOU EVER BEEN ANNOYED BY A PAG- ing system that makes the speaker difficult to understand, or by a stage- show performer who rattles the speak- ers by singing loudly into a micro- phone? Most people assume that the equipment is malfunctioning, and that repairs are needed. However, in many cases that's not so; and the real culprit that's causing the distortion is audio- level mismatching. Basically, if the gain of an audio amplifier is adjusted for a small input signal, and a large signal is applied, then the amplifier is driven beyond its capabilities and distortion results, even though the amplifier is working perfectly. And, if the amplifier is ad- jusled for a strong input signal, and a weak signal is applied, then it is diffi- cult to understand what the speaker is saying. In either case, it sounds awful, and the message doesn't get across. However, if you build the cir- cuit described in this article, it will eliminate those kinds of problems; the circuit maintains a constant output- voltage level, regardless of the input signal. The circuit produces no clipping, which would flatten the peaks of the signal, and virtually zero distortion, because the shape of the output signal is a true replica of the shape of the input signal. The circuit introduces little noise, so none is heard at the output. Pumping, or changes in am- plifier gain that can be detected by the listener, is almost imperceptible. Transient spike handling is excel- lent — if it weren't, the I i miter would not be fast enough to control in- stantaneous fast-rising spikes, such as a percussive sound. Volume limiters aren't always de- sirable. For example, the circuit we'll present was installed in a church PA system to compensate for the different voice levels of the various members of the congregation who made short an- DUTPUT LEVEL SET, VARYING AMPLITUDE: ji V INPUT /"\1 NPUT S*9 VARIABLE BAIN AMPLIFIER CONSTANT AMPLITUDE FIG. 1— BLOCK DIAGRAM of the audio I im- iter. The feedback loop of IC1-a controls the gain of the circuit. nouncements. Everyone loved it — ex- cept the minister. After the sermon, he very strongly requested that a switch be installed that could disable the li miter. It seems that he preached fire-and-brimstone, and he wanted to rattle the speakers. Circuitry Figure 1 shows the block diagram of the audio I i miter. Amplifier ICl-a can change its gain from Vmlh to X 100, depending on the net effect of its feedback loop. That way, the over- all gain of the circuit is such that the output level remains constant. If we put a potentiometer in the feedback loop of ICl-a that we could continu- ously adjust to maintain a steady out- put level, that would do the trick. However, that would be extremely im- practical, as well as being boring; what we need is a resistor that can instantly change its value in accor- dance with the output voltage of ICl-a. An optically coupled Light-Dependent Resistor, or LDR would do the trick. An optocoupler is a device that contains both a light source (an LED) and some kind of light-sensitive de- vice (in this particular case it happens to be an LDR) inside one package, > do o X 5 w o z 1 LU _l LU o □ < CJ J2 22|iF OUTPUT 22^F 1M11 FIG. 2— SCHEMATIC OF THE VOLUME LIMITER. IC1-a is connected as an inverting amplifier whose gain is controlled by the LDR portion of an optocoupler. CHASSIS nfr, GROUND .|-- ; -,^ J2 OUTPUT FIG. 3— FOLLOW THIS PARTS-PLACEMENT DIAGRAM if you are using the PC board. PARTS LIST All resistors are 1 j-watt, 5%. D1-D6— 1N914 diode R1— 10,000 ohms Other components R2— 1 megohm J1.J2— RCA jacks R3, R7— 100,000 ohms Miscellaneous: power supply, proj- R4 — 300,000 ohms ect case, wire, solder, etc. R5— 1000 ohms Note: A kit of parts, a PC board, R6— 100 ohms and assembly instructions Capacitors (power supply and enclosure C1. C2, C6, C7, C9, C10-22 u.F, 35 not included) Is available for volts, electrolytic (a larger value will $48.00, and a single PC board is also do) available for S25.00, from Woods C3, C5— 100 pF, 50 volts Electronics Inc., 4233 Spring St. C4. C8— 0.1 nR 50 volts #117, La Mesa, CA 92041 (619) Semiconductors 265-2551 (order # AVL-42889-K). IC1— NE5532 low-noise audio ampli- An assembled and tested unit is fier (Signetics) also available for $57.00 (order IC2 — VTL-5C4-2 optocoupler device # AVL-42889-A). Check or (Vactec) money order, only. with the leads of both brought out to external pins, much like an IC. When the LED is turned on via an external input voltage, the LDR's resistance is very small, and when the LED is turned off, the LDR's resistance be- comes very large. The resistance of the LDR can therefore be varied at a very fast rate, according to the inten- sity of the light from the LED. So let's use the LDR portion of an op- tocoupler in the feedback loop of our amplifier to produce a gain-control- ling circuit. Now, to be more specific, we need an optocoupler with an LDR that can reduce its resistance instantly when its input signal reaches the limiting threshold, thereby reducing the gain of the amplifier to just below the threshold. Then we'd like it to stay at that value until the input signal be- came weaker, and then gradually in- crease the gain until the threshold is reached. Fortunately, the VTL-5C4-2 from Vactec Inc. {10900 Page Blvd., St. Louis, MO 63I32) has exactly those characteristics. When the light source is illuminated, the resistance decreases in a matter of microseconds (very fast with respect to audio fre- quencies), and when the light source is removed, the resistance increases over a period of seconds (very slow with respect to audio frequencies). Those combined characteristics can form a limiting circuit that produces a constant output level, but whose ac- tion is not easy — in fact, quite diffi- cult — for the listener to detect. Figure 2 shows the schematic of the volume limiter, ICl-a is connected as an inverting amplifier; ignoring the LDR (assume that its resistance is very high so that it doesn't affect the feedback loop), the gain is R2/RI, or 100, Standard low- impedance-micro- phone preamplifiers have a gain of 100. Thus, the output at ICl-a pin 1 will be about 2 volts p-p. The second half of the amplifier, ICl-b, is connected to the output through C4, and its gain is R4/R3, or 3. The optocoupler's LED turns on when the voltage across it is about 2 volts. The higher the current through it. the brighter it illuminates. On positive peaks, it is in series with Dl and D2, and on negative peaks it is in series with D3 and D4. Since D1-D4 are silicon diodes, about 0,7 volts is dropped across each one before they begin to conduct. Therefore, the total positive voltage across the bridge re- quired to illuminate the LED is 0.7V + 0.7V + 2V, or slightly less than 3.4 volts. The same voltage with a negative polarity appearing across 40 the bridge will also illuminate the LED. As the AC signal at ICl-b pin 7 approaches 6. 8- volts AC, the LED re- ceives short bursts of current, and the LDR instantly reduces in value to a point where it reduces the gain of IC1- a, thereby reducing the output of IC1- b pin 7 to less than 6.8 volts AC. Because of the slow recovery time of the LDR, it appears effectively as a fixed resistor and therefore produces virtually no distortion. The output voltage, 6. 8- volts AC, when divided by the gain of ICl-b, is about 2- volts p-p, which is a standard line level. Since the LDR can go below 100 ohms, the gain of ICl-a can be re- duced to LDR/RL or Hqoth-. That means that signals up to 200- volts p-p can be- applied to the input (although you'll never have an input with that magnitude), while maintaining the output at a line level; any input signal ranging from mi crop hone- level to 200 volts will produce a clean line-level output. I f R5 were left out of the circuit, the output level would be so constant that a monotone sound quality would re- sult. By putting a little resistance in series with the bridge, the output volt- age will be allowed to vary a little, and the sound is much more natural. A IK resistor is a good choice for R5, but try out other values for yourself. You may also want to try other R2/RI and R4/R3 ratios. The NE5532 (IC1) is a relatively expensive dual op- amp with very-low- noise characteristics. If you can toler- ate some noise, feel free to use a 741 , 324, or any other general -purpose au- dio op-amp. If you do, note that the pin numbers may change. Also, CL C2, C6, and C7 are used to block DC. If no DC exists in your design, then you may omit them. R6 is included for spike protection; if no dangerous spikes will exist, you may omit that resistor, too. Capacitors C3, C5, and C8 are included as standard practice, but if no undesirable effects occur, you may omit them. Use any regu- lated supply voltage, such as two 9- volt batteries or a ± 1 2- volt DC sup- ply. Just don't exceed the maximum voltage ratings of the IC that you de- cide to use. The current drawn by the circuit will depend on the op-amp that you decide to use for the project, but it will never be more than a few milli- amps per op-amp section. If you want to operate without a negative supply, then connect IC! pin 4 to ground, and create a V cc 12 sup- ply with another unity-gain op-amp section and a voltage divider. Then connect all the ground connections except for the input and output grounds to that, and connect IC1 pin 8 to V cc (just reference everything up to V cc 12). Always use at least 15- volts DC— preferably 24- volts DC. Also, the optocoupler used for the project is a dual-element type; they are more versatile. However, you can use the VTL-5C4 (the single-element version) if you like. Building the circuit Because ICl-a may have a gain of up to 100, you must keep the leads short in that circuit. Ground loops can defeat any circuit, so keep all power- supply grounds together on one side of the board. Also, remember to use shielded wire on the input and output connections. You can use point-to- point wiring on perforated con- struction board, but it's best to use the foil pattern provided in PC Service to make a board and use that instead. A ready-to-use PC board is also avail- able from the source mentioned in the parts list. Figure 3 shows the parts-placement diagram for the audio limiter. Be sure to check for solder shorts and all of that other bad stuff before powering up and testing the circuit. RCA-type jacks are probably the best choice for J I and J2, but use whatever best suits your application. To test the circuit, simply connect a microphone, and observe the output on an oscilloscope, or listen to it through a headset (to cut out feed- back). The output should remain at the same level, regardless of whether you whisper or scream into the micro- phone. A note of caution; Remember that the limiter works to correct the gain by looking at seldom-encoun- tered maximum peaks. If you feed in a sine wave, you will notice that the output indeed remains constant, no matter what the input voltage, but a "blip" appears on each and every peak (which would imply high distor- tion), (n a normal audio signal, not all peaks are the same amplitude, and only seldom-occurring maximum peaks are acted upon. Since they oc- cur very infrequently (as compared to audio frequencies), the distortion of the limiter is actually very low- — -you won't even notice it. R-E Put Professional Knowledge and a COLLEGE DEGREE in your Technical Career through HOME _,„ STUDY ^ Add prestige and earning power to your technical career by earning your Associate or Bachelor degree through directed home study. Grantham College of Engineering awards accredited degrees in electronics and computers. An important part of being pre- pared to move up is holding the right college degree, and the^bso- lutely necessary part is knowing your field. Grantham can help you both ways — to learn more and to earn your degree in the process. Grantham offers two degree pro- grams — one with major emphasis in electronics, the other with major emphasis in computers. Associate and bachelor degrees are awarded in each program, and both pro- grams are available completely by correspondence. No commuting to class. Study at your own pace, while continuing on your present job. Learn from easy-to-understand lessons, with help from your Grantham instruc- tors when you need it. Write for our free catalog (see address below), or phone us at toll-free 1-800-955-2527 (for catalog requests only) and ask for our "degree catalog." • Accredited by the Accrediting Commission of the National Home Study Council GRANTHAM College of Engineering 5 10570 Humbolt Street ° Los Alamitos, CA 907201 41 lU^MM^^Z .; •. ALL ABOUT ATTERIES o Q Q < 42 Selecting the right batteries for a particular application can be frustrating, especially when you have to choose between so many different types. This article will help you make your next selection. JOSEF BERNARD BATTERIES, BATTERIES. AND STILL MORE batteries. There are "C" cells, "D" cells, "AA" cells, and button cells of all varieties. The assortment you'll find, even just hanging on a super- market rack, boggles the mind; there are regular, heavy-duty, "classic," al- kaline, lithium, mercury, nickel-cad- mium, and air-zinc cells. Simply making a decision about which type to use , even when you have no choice about the size of the cell you're re- placing, can be confusing; and if you're designing a piece of equip- ment for battery operation, the prob- lem is magnified enormously. In this article we'll try to make clear some of the reasons behind the multitude of battery types, and present some guidelines for choosing among them. A short course To begin with, a battery is made up of cells. An individual cell usually outputs about 1.5 volts, although the figure may be higher or lower, de- pending on the materials involved. A battery of cells must be used when you need to produce more voltage or current than can be delivered by a single cell. A battery produces electricity through an oxidation-reduction chem- ical reaction involving two dissimilar materials, in which electrons are transferred from one to the other. If you extract the electrons at some point along their path of travel, you can put them to work for you. The voltage and current that a given pair of materials will produce are largely determined by their places in the electromotive series, which lists the elements ac- cording to the degree to which they react with oxygen. The greater their separation along the series, the great- er the potential they will produce. zmaiui COPPEfl(Cu) FIG. 1— A SIMPLE ENERGY-PRODUCING cell can be constructed from two dis- similar metals such as copper and zinc immersed in an acid electrolyte. Any high-school chemistry book can provide you with detailed information on how the electron-producing reac- tions work. And. if you have fillings in your teeth and have ever bitten down on a coin or a piece of gum- wrapper foil, you have experienced (and tasted) firsthand how a simple battery works. A simple, lab-experiment energy cell is illustrated in Fig. 1. In princi- ple, all energy- producing cells have the same three principal components. They are: Anode: the material that is oxidized and gives up electrons during the chemical reaction. The anode is usu- ally marked with a " - ." Cathode: the material that is reduced (releases oxygen) and accepts elec- trons during the reaction. It is usually marked with a " + , " Electrolyte: the conductor through which electrons travel from the anode to the cathode as ions. The electrolyte is usually a "wet," or at least a damp material. Note that, contrary to customary usage in electronics, the anode is the negative electrode of an energy cell and is indicated with a " — ." The positive electrode, marked with a " + ," is the cathode. In a rechargea- ble device, the functions of the elec- trodes are reversed during charging however, and conventional termi- nology then applies. Cells and batteries are divided into two types: primary and secondary. Primary cells, which include the common throw-away "flashlight bat- tery" types, expend their energy and, when their chemicals are exhausted, they must be discarded. Secondary cells are rechargeable (the chemical action is reversed by forcing a reverse flow of electrons), and include nickel - cadmium types and the lead-acid bat- teries used in automobiles. Leclanche cells Figure 2 shows the construction of an ordinary carbon-zinc D-size cell. The anode, cathode, and electrolyte are just a few of the components of a modern-day dry cell. Many of the others, though, such as the paper sep- arator, serve just to "fine-tune" the performance of the device. That type of dry cell belongs to a class called "Leclanche cells" (sometimes pro- nounced Le-clan-SHAY) cells. They are named after Georges Leclanche, the Frenchman who produced the first carbon-zinc cell in 1866. Because carbon-zinc cells are in TAL COVER (POSITIVE TERMINAU" AIR SPACE ■ ASPHALT SEAL ■ ANODE (ZINC CAN) ■ SEPARATOR - ELECTROLYTE : INSULATING CUP- -VENT WASHER I -SUPPORT WASHER -CATHODE CARBON -CATHODE CURRENT COLLECTOR -JACKET METAL BOTTOM (NEGATIVE TERMINAU FIG. 2 — THE "CLASSIC" DRY CELL uses a zinc can as anode, an ammonium/zinc- chloride electrolyte, and a manganese-dioxide cathode mix. The carbon rod plays no active part in the electron-producing reaction. PLATED STEEL TOP COVER ■ (POSITIVE TERMINAU INSULATING WASHER- PITCH SEAL- Aia SPACE - SEAL WASHERS* SINTERED CARBON- ELECTRODE COATED SEPARATOR ■ INSULATING WASHER - ABSORBENT KRAFT LINER JACKET ACETATE LABEL POLYETHYLENE -CATHODE MIX PLATED STEEL BOTTOM COVER (NEGATIVE TERMINAL) -ZINC CAN FIG. 3— THE PAPER SEPARATOR used in more recent dry-cell designs requires less j; space than the older paste-type, thus allowing the inclusion of more cathode mix and g making possible a greater energy density. o 43 Take any one of these HANDBOOKS ELECTRONICS and CONTROL • your one source for engineering books from over 100 different publishers • the latest and best information in your field • discounts of up to 40% off publishers' list prices c/3 O 2 o rr H O HI _J LU I O Q < 44 322/910 Publisher's Price $114.50 ANTENNA ENGINEERING HANDBOOK, Second Edition Edited by R. C. Johnson and H. Jasik • 1,408 pages, 946 illustrations • covers all types of antennas currently in use with a separate chapter devoted to each • provides detailed data on physical fundamentals, operating principles, design techniques, and performance data • up-to-the-minute information on antenna applications • a must for those involved in any phase of antenna engineering Publisher's Price $75-00 STANDARD HANDBOOK OF ENGINEERING CALCULATIONS, Second Edition ByT.G. Hicks • 1,468 pages, 793 illustrations, 499 tables • puts more than 1,100 specific calculation procedures at your fingertips • every calculation procedure gives the exact, numbered steps to follow for a quick, accurate solution x • virtually all procedures can be easily programmed on your PC or calculator • uses USCS and SI units in all calculation procedures 287/35X 047/790 Publisher's Price $98.50 TELEVISION ENGINEERING HANDBOOK Edited by K. B, Benson • 1,478 pages, 1.091 illustrations • packed with all the technical information today's engineer needs to design, operate, and maintain every type of television equipment • extensive coverage of receivers, broadcast equipment, video tape recording, video disc recording, and the latest technological advances • provides television system and industry standards for the US. and other countries • the most comprehensive; book on the subject of television engineering for only $14.95— when you join the ENGINEERS' BOOK CLUB Publisher's Price $89.95 MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL By J. T. Markus • 1,264 pages, 3,666 circuit diagrams • a handy, desktop reference with 103 chapters organized hy "family" grouping • filled with predesigned and use-tested circuits to save you production time and money • includes concise summaries of all the recent applications notes, journal articles, and reports on each circuit, efficiently organized and indexed for the practicing engineer Publisher's Price $8950 ELECTRONICS ENGINEERS' HANDBOOK, Third Edition Edited by D. G. Fink and D. Christiansen • 2,496 pages, 1,600 illustrations • the definitive reference to electronics engineering • fully updated to cover all recent advances and developments • ranges from essential principles and data to the latest design solutions and practical applications — with an all-new chapter on standards • written and compiled by more than 170 contributors — all experts in their fields M 209/820 4 reasons to join today! 1, Best and newest books from ALL pub- lishers! 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A shipping and handling charge is added to all shipments. 1 wish to order the following book: □ ANTENNA ENGINEERING HANDBOOK (522/910) D MODERN ELECTRONIC CIRCUITS REFERENCE MANUAL (404/4(31) □ ELECTRONICS ENGINEERS' HANDBOOK, 3/e (209/820) [~i TELEVISION ENGINEERING HANDBOOK (047/790) □ STANDARD HANDBOOK OF ENGINEERING CALCULATIONS (287/35X) Stgnaiu re Nairn. Address O ■J. O 47 w o z o EC (- o 111 _l 111 6 o < 48 such widespread use, it will pay to devote a paragraph or two to a discus- sion of the elements of which they are comprised. Figures 2 and 3 show car- bon-zinc cells using paste and paper separators, respectively. (Because a paper separator occupies less space than the paste type, paper-separator cells can contain more reactive mate- rials and produce about ten percent more power.) The anode is a zinc can, zinc being one of the two reactive materials in the cell. The can also serves as a con- tainer for the other cell materials. To- day, zinc cans are usually enclosed in a steel jacket, which increases du- rability and helps to contain leakage, should that occur. Lining the inside of the can is the paste or paper separator. Its purpose is to physically and electrically isolate the positive and negative electrodes while permitting electrolytic or ionic conduction to take place through the electrolyte. The paste contains elec- trolyte and a gelling agent such as starch or flour. The paper-type sepa- rator is coated with a gelling agent and impregnated with electrolyte that is squeezed out of the cathode mate- rial during manufacture. Ordinary general-purpose Leclanche cells use an electrolyte made of ammonium chloride (NH 4 C1), zinc chloride (ZnCl 2 ), and water. In "heavy-duty" cells, the electrolyte is almost entirely zinc chloride and water. The bulk of the cell consists of the cathode mix, also known as the "bob- bin," "black mix," or "depolarizer." Its constituents are manganese diox- ide (Mn0 2 ), carbon black, and elec- trolyte. The purpose of the carbon is twofold: it holds the electrolyte and adds electrical conductivity to the mix. Some cells use a very pure elec- trolytically derived form of Mn0 2 known as EMD (Electrolytic Man- ganese Dioxide). Although that makes them more expensive, it also makes for an extra-heavy-duty device. A carbon rod is inserted at the center of the bobbin, which is the cell's cur- rent collector (electron source). The semi-porous rod also acts as a vent for hydrogen gas. Note that although the Leclanche cell is frequently called a carbon-zinc (or zinc-carbon) type, carbon does not take part in the chemical reaction that produces electricity. The active ingredients are zinc and the man- ganese compound(s). FIG. 4— THE LARGE ELECTRODE area of the Polapulse battery gives it the power to deliver enormous quantities of current. volts, although a brand-new one may be measured as high as 1 .75-1 .8 volts. A general-purpose Leclanche cell has an energy density of about 30 watt- hours per pound. A special form of the carbon-zinc design is the Polapulse battery (Fig. 4) used to power Polaroid instant cam- eras. Its thin, flat construction makes possible electrodes with large surface areas. That, in turn, gives it a large capacity — as much as 19 amperes of instantaneous current! A Polapulse experimenter's kit is available from Powercard Corporation, 391 Totten Pond Road, Waltham, MA 02154 (617) 890 6789. The P100 Designer's Kit contains five P100 batteries and a special holder for them; it costs $17.50, and Massachusetts residents must add proper sales tax. Alkaline cells Alkaline cells derive their name from the fact that their electrolyte is the highly caustic base, potassium hy- droxide (KOH), rather than a slightly acidic one containing a salt such as ammonium- or zinc-chloride. The de- sign of an alkaline cell, although su- perficially similar to that of a carbon- zinc one, is really significantly dif- ferent, as can be seen in Fig. 5. The cathode material of an alkaline cell is EMD, the electrolytically de- rived manganese dioxide sometimes PLATED STEEL - POSITIVE COVER POTASSIUM HYDROXIDE - ELECTROLYTE MANGANESE DIOXIDE, CARBON CATHODE NON-WOVEN FABRIC- SEPARATOR METAL WASHER - NYLON SEAL PLATED STEEL METAL SPUR BRASS RIVET NEGATIVE COVER FIG. 5 — TYPICAL OF MANY alkaline cells is "inside-out" construction, where the cathode material is exterior to that making up the anode. The no-load voltage developed by a used in carbon-zinc cells to improve carbon-zinc cell is nominally 1.5 performance. It is mixed with water, FIG. 6 — THE "JELLY ROLL" construction of atypical nickel-cadmium cell gives it a large electrode area. Note the vent mechanism to protect against cell rupture resulting from the generation of gases during charging. carbon or graphite (ten percent or a bit more), and some potassium-hydrox- ide electrolyte. As in a Leclanche cell, the anode is made of zinc, but the metal is in finely powdered form and the cell is contained in a steel jacket. The highly purified zinc powder is treated with mercury to form an amalgam; that greatly re- duces the production of hydrogen, caused by the metal reacting with the potassium hydroxide electrolyte that pervades it. The separator that is used is made of a porous woven, felted, or bonded material. In a cylindrical alkaline cell, the central element is the anode collector, not the cathode collector used in car- bon-zinc cells. That piece, which may be made of brass, is mechanically and electrically connected to the bottom ( - ) terminal of the cell. That sort of "inside-out" construction is fre- quently used in dry-cell designs. Alkaline cells have an open-circuit rating of about 1.52 volts, and an ener- gy density of about 45 watt-hours per pound. Their performance at tem- perature extremes exceeds that of car- bon-zinc types. Their low-current- drain performance is also better, but where alkalines are best where mod- erate-to-high currents are drawn over an extended period. Making a choice Carbon-zinc and alkaline cells are available in a wide variety of packag- ings and voltages. Fortunately, if it's just a replacement battery you're looking for when you walk into the store, you don't have to worry too much about your decision. The equip- ment into which the replacement cell or battery will be inserted can take only a particular size, and that size is usually keyed to the voltage. What you have to concern yourself with is the way the replacement performs — its behavior at various temperatures and, more important, its ability to de- liver the current that your application requires. The literature provided with a dry-cell-operated device frequently recommends a specific type of cell or battery, but does not explain why that particular sort is called for. The next few paragraphs will help you to make a more informed decision about re- placement cells, and in choosing a power source for something you may be designing. Although alkaline cells have largely replaced carbon-zinc types in most applications, there are still some places where the latter will give a better price-performance ratio than the more glamorous type. Such situa- tions are typically those where current drain is light but constant (no surges of current are called for by the device) and the operating temperature is a comfortable one. Carbon-zinc cells have a relatively short shelf or storage life, so they are best suited to applica- tions where they will be used imme- diately; not where they will be expected to remain quiescent for long periods awaiting emergency use. In a C-cell-powered wall clock it may prove more economical to install a regular carbon-zinc cell than an al- kaline one; while the alkaline cell may last a bit longer, its extra cost will offset any economy that might be gained from its somewhat longer life. Heavy duty carbon-zinc cells made with somewhat higher-quality mate- rials can even be used to power small transistor radios, provided not too much demand is made of them. Alkaline cells, with their ability to source heftier currents than carbon- zinc ones and to depolarize, or re- cover, more quickly after heavy use, are better suited for the workload pre- sented by much of today's consumer- electronics equipment; cassette play- ers, boom-boxes, portable TV's, and the like. Devices that might suck car- bon-zinc cells dry in twenty minutes can run for several hours on alkalines. > o i 49 An Eveready brand called the "Con- ductor" promotes itself as being best for audio applications. While that was the case when it was first introduced, due to the use of premium compo- nents, the design of "ordinary" al- kaline cells is today virtually identical to that of the Conductor brand, and there is little, if any, difference in performance. Other properties of alkaline cells may also make them the better choice in certain applications. They have a longer shelf or storage life, and their output voltage falls off less rapidly than does that of carbon-zinc cells. Incidentally, you can extend the stor- age life of carbon-zinc cells by keep- ing them refrigerated to slow the chemical reactions that take place in them even when they are not being used. Because those reactions take place much less actively when al- kaline cells are not in use, alkaline cells do not benefit as much from re- frigerated storage. Low temperatures cause voltage drop-offs in all types of energy-pro- ducing cells and batteries. Again, al- kaline cells provide greater reliability over a greater temperature range than do carbon-zinc ones. As the tem- perature of a carbon-zinc cell drops below freezing, its voltage, and par- ticularly the current it is capable of delivering, fall rapidly to unusable levels. While alkaline cells are sim- ilarly affected by low temperatures, their performance is better than that of even the best carbon-zinc cells. Don't be swayed by those commer- cials that say things the likes of "Ours last 30 percent longer than..." The comparison is probably being made between the manufacturer's current production and the same product as he formulated it several years ago — not between his and somebody else's products. Virtually all alkaline cells produced today by the major man- ufacturers are considerably longer- lasting than those of a few years back due to the fact that changes in the construction of the shell (namely, re- ducing it to a single steel container with a thin plastic overcoating) has g resulted in the ability to cram more z reactive material inside. The voltage, § of course, doesn't change, but the o ability to deliver current does. LU _1 5 Rechargeable cells 5 Areyoutiredofreplacingwora-out g dry cells all the time? Maybe you're COLLECTOR NEGATIVE ANODE CAP \ ! ELECTRODE (Li) INSULATION \ \ POSITIVE PACING \ \ ELECTRODE iMnO,) ORGANIC ELECTROLYTE CATHODE CAN- 1 AND SEPARATOR SNAP > CONNECTOR ASSEMBLY FIG. 7— LITHIUM CELLS have extremely high energy densities. The button-style packaging shown in a provides a large electrode area. Three 3-volt lithium cells are connected in series to make a 9- volt transistor-type battery (b). tempted to replace them entirely with rechargeable nickel-cadmium cells. But nickel-cadmium cells (com- monly called "Nicads," although that's actually a trademark owned by one manufacturer, Saft) have their pros and cons. The internal details of a typical nickel-cadmium cell are shown in Fig. 6. The active materials are nickel oxide (NiO), which forms the cell's positive plate; cadmium (Cd) for the negative plate; and the highly caustic potassium hydroxide (KOH) electro- lyte. Several different manufacturing techniques may be used but, in gener- al, the positive and negative elec- trodes form a "sandwich" with the potassium-hyd rox ide -saturated sepa- rator in the middle. Those three layers are wound into a jelly-roll-like spiral. The separator can be either nylon or a polypropylene material; the latter makes possible greater cell capaci- ties. A safety vent is provided to pre- vent cell rupture resulting from pressure buildup during extremes of charge or discharge. Normal-rate recharging is per- formed at the rate of one-tenth the rated current of a cell. For example, it takes 60 milliamperes to charge an AA-size cell rated at 600 rnAh, for 14 to 16 hours. Quick-charge cells can be recharged in four to six hours, and fast-charge devices can be charged in as little as one or two hours, at much higher currents. Safeguards in the form of voltage or temperature sen- sors must be provided to prevent cell rupture or internal plate damage due to the high internal pressures and tem- peratures that may be generated dur- ing the fast-charge process. The differences in charging rates are made possible by a number of different factors, including electrode design, and the choice of reactive ma- terials; they are still nickel and cad- mium, but in different formulations. Aside from a reduced charging time, the differences between regular-, quick-, and fast-charging cells are more or less transparent to the user. There is, however, a slight reduction in internal resistance in fast-charging cells, resulting in a nominal (on the order of millivolts) voltage increase, and the ability to better provide surge current. Nickel-cadmium cells have a much flatter voltage-drop curve over their working life than do Leclanche and alkaline designs — a fact that may be worth considering. Immediately after charging, their open-circuit voltage is about 1.4 volts, which drops almost immediately to about 1.25 volts, a level that is maintained until their charge is nearly depleted. They can provide very large amounts of current when needed, and hold up well under conditions of continuous drain. Nick- el-cadmium cells also provide good power output under extremes of tem- 50 FIG. 8— RECHARGEABLE lithium cells are intended principally lor maintaining the contents of solid-state memories. perature range. Nickel-cadmium cells perform best when worked hard. If discharged just shallowly and then charged imme- diately, they will develop a "memo- ry" for that sort of use and eventually lose some of their capacity. However, because of slight changes in cell chemistry, that's far less of a problem than it was just a few years ago. Most manufacturers insist that memory effects no longer exist. The working life of a nickel-cadmium cell on a single charge is only about 70 percent of that of an equivalent-size alkaline cell. Nickel-cadmium cells are most useful where they can be built into a device and the charging current sup- plied from the outside through a jack, or internally, directly from it. If re- chargeables are used as replacements for throwaway primary cells, you gen- erally face the inconvenience of re- moving them from the device for charging, and then removing them again from the charger and replacing them in their compartment for use. When replacing old or worn-out ceils in a nickel-cadmium battery pack, re- place them all at once — mixing old and new ones can lead to the weakest of them reversing its polarity and af- fecting the life and performance of the entire pack. Rechargeable lead-acid cells and batteries (similar to the one in your car, but smaller) use lead, lead oxide, and sulphuric acid, and come with a gelled electrolyte that allows them to be used in portable equipment with- out fear of spillage. Lead-acid tech- nology is also available in the form of sealed D-size cells. The nominal volt- age of a lead-acid cell is 2.0 volts, and it is capable of sustaining very high rates of discharge. The performance of lead-acid cells falls off at cold and very warm temperatures. Unlike nickel -cadmium cells, lead-acid cells must be kept we 11 -charged if you ex- pect them to perform efficiently over a long lifetime. Lithium cells Lithium is an extremely reactive metal, and its high place in the elec- tromotive series makes it an excellent candidate for inclusion in energy cells. Unfortunately, its high degree of activity (it reacts violently with water, for example) makes it difficult to work with . Many of the difficulties have been overcome, however, and lithium-based cells are now found widely in watches, cameras, cal- culators, and in situations where a small trickle of current is required to maintain the contents of solid-state memory in a standby state. Lithium cells are very efficient, with energy densities on the order of 90 watt- hours per pound. The major reason lithium cells are not more widely used (although that is changing) is the dif- ficulty in manufacturing large-size ones that are safe to use. Although there are a number of lithium-cell formulations, the one using lithium, manganese dioxide (Mn0 2 ) and a lithium perchlorate (LiCld 4 ) electrolyte in an organic sol- vent (water cannot be used, re- member) makes up about 70 percent of the lithium-cell market. Carbon monofluoride is also used. Much of the remaining portion consists of cells made using a iithium-carbon-thionyl chloride (S0C1 2 ) formulation. Figure 1-a shows the construction of a typ- ical lithium "button" cell; Fig. 1-b shows how Kodak combines three manganese-dioxide-type lithium cells in one package to produce a nine-volt, "transistor-type" battery. The output of a lithium/Mn0 2 cell is nominally three volts; in some ap- plications it may be possible to re- place two 1.5-volt carbon-zinc or alkaline cells with one lithium one. By using a lithium/ferric-sulphide (FeS 2 ) combination, a lightweight and powerful 1.5-volt cell can be pro- duced. One of the great benefits of using lithium cells is their extremely long shelf life; five years or even ten. Under conditions of low drain, their useful working life may almost equal that figure. A rechargeable lithium/Mn0 2 but- ton cell has recently been introduced by Sanyo (see Fig. 8). It is intended primarily as a replacement for the Ni- Cd cells and large- value capacitors used in keeping memory circuits alive. Other types While the types of energy cells al- ready described can fill most elec- tronics needs, actual and anticipated, there are a few additional kinds that bear mentioning. Mercury cells have long been used as a compact power source in devices such as hearing aids and cameras. They use a mercuric-oxide cathode, powdered-zinc anode, and a po- tassium hydroxide (KOH) or sodium hydroxide (NaOH) electrolyte. The output voltage is 1.3 volts, and re- mains stable over a long life of storage or use. Silver-oxide cells are also used for similar applications (see Fig. 9). FIG.9— THIS SILVER OXIDE battery is often used in cameras. Another type of energy cell found in hearing aids and watches is the zinc-air, or just plain "air," cell. It uses atmospheric oxygen to produce electrochemical energy Zinc -air but- ton cells use a powdered-zinc -with- potassium- hydroxide-electrolyte anode and have a very thin cathode region incorporating a catalyst. Oxy- gen in the air provides the cathode material. Although they are not able to output large amounts of current, zinc-air cells have very high energy densities. Because air is kept out by a pull tab until a zinc -air cell is ready to be used, its shelf life is extremely long. A zinc-air cells's output voltage of about 1.4 volts remains stable over a working life of several hundred hours before falling rapidly to an un- usable level. There are, of course, still many more types of energy-producing cells, primary and secondary. Some are being produced today, some are still in the experimental stage, and others s have been abandoned either for prac- 3> tical reasons or because they have S been rendered obsolete by newer bat- 5 tery designs. R-E o 51 RAY MARSTON WORKING WITH AUDIO POWER AMP IC'S Building your own amplifier circuits for audio applications doesn't have to be difficult. In this article we show you how easy it is to use several of the more popular audio-amplifier IC's. g z o EC £ UJ o Q < AN IDEAL AUDIO POWER AMPUEiSCR CAN Bl£ simply defined as a circuit that can deliver audio power into an external load without generating significant distortion, and which does so without overheating or consuming excessive quiescent current. In practice, circuits that come very close to that ideal can easily be built using modern inte- grated circuits. Simple* audio-power amplifiers with outputs up to only a few hundred milliwatts can be easily and cheaply built using little more than a standard op-amp and a couple of general-pur- pose transistors. For higher power lev- els, a wide range of special-purpose "single" or "dual" audio-power am- plifier IC's are available, which can provide maximum outputs ranging from a few hundred milliwatts to roughly 20 watts. The specific IC chosen for a given application de- pends mainly on the constraints of the available power-supply voltage and on the required output power. This article will look at a wide selection of prac- tical IC- based audio-power amplifier circuits. Low-power circuits The ever-popuiar general-purpose 741 operational amplifier can supply peak output currents of at least 10 mA, and can provide peak output- voltage swings of at least 10 volts into a IK load when powered from a dual power supply of plus- and minus-15 volts. The IC can supply peaks of about 100 mW into a IK load. Among the reasons for the 741's popularity is that it can easily be used as a simple low-power audio amplifier, as shown in Figs. 1 and 2. Figure I shows how to use the 741 with a dual power supply. There, the external load is direct-coupled be- f ,0K I \V JlOOK INPUT , 741 J>M 15V [Y SPKR Q— R3 ; > 1K T0TAI I / FIG. 1— LOW-POWER AMPLIFIER using dual power supplies. ■-+30V /TOTAL FIG. 2— LOW-POWER AMPLIFIER using 8 single-ended power supply. FIG. 3— BASIC BOOSTED-OUTPUT-cur- rent unity-voltage-gain op-amp circuit. tween the op-amp output and ground, and the two input terminals are ground-referenced. The op-amp is operated in the non-inverting mode, and has a voltage gain of X 10 (R1/R2) and an input impedance of 47K (R3). Figure 2 shows how to use the cir- cuit with a single-ended power sup- ply. In that case, the external load is AC -coupled between the output and ground, and the output is biased to a quiescent value of hair of the supply voltage (to give maximum output- voltage swing) via the R1-R2 divider. The op-amp is operated in the unity- gain non-inverting mode, and has an input impedance of 47K (R3). In Rgs. I and 2, the external load must have an impedance of at least IK. If the external speaker has an im- pedance lower than that, the resistor R x must be connected as shown to the schematic to raise the load to a total of IK; R x inevitably reduces the amount of power that actually reaches the speaker. Boosted-output circuits The available output current (and thus the power} of a standard op-amp can easily be boosted by wiring a complementary emitter- follower be- tween its output and its non- inverting input terminal, as shown in Fig. 3. Note that the circuit is configured to give an overall unity voltage gain, but that the base-emitter junctions of Q\ and Q2 are both wired into the nega- tive-feedback loop of the circuit, so that their effective forward- voltage drops (approximately 600 mV) are re- duced by a factor equal to the open- loop voltage gain of the op-amp. So, if the open-loop gain is 10,000, then the effective forward voltage drops of Ql and Q2 are each reduced to a mere 6 |xV, and the circuit generates negli- gible signal distortion. In practice, the open-loop voltage gain of an op-amp actually falls off at a rate of about 20 dB/octave, so that although the signal distortion of the circuit in Fig. 3 may be insignificant at 10 Hz, it may become quite objec- tionable at 10 kHz. That problem can 52 FIG. 4— OP- AMP POWER AMPLIFIER using dual supplies; output power is about 280 mW, maximum. FIG. 5— OP-AMP POWER AMPLIFIER using a single-ended supply, be overcome by applying a small amount of forward bias to Ql and Q2, as shown in figs. 4 and 5, so that their forward-voltage drops are reduced to near-zero and the result is that the distortion is minimized. The circuits of figs. 4 and 5 are designed to produce output currents up to 350 mA peak, or 50-mA RMS into a load of at least 23 ohms, there- by producing up to 280 mW RMS. The limitations are determined by the current/power ratings of QI and Q2, and by the power-supply voltage . The Fig, 4 circuit is designed for use with dual power supplies, and gives a volt- age gain of 10. The fig. 5 circuit uses a single-ended supply, and has unity voltage gain. Power-amplifier basics [f output powers in the approximate range from 200 mW to 20 watts are needed, the most cost-effective way of getting them is to use a dedicated IC to do the job. A wide range of such IC"s are available, in either "single" or "dual" form. Most of them take the effective form of a simple op-amp with complementary emitter-follower output stage (like Figs, 3-5); they have differential input terminals and can provide high output current/ power, but consume a low quiescent current. INPUTC FIG. 6— AN AMPLIFIER CONNECTED in the single-ended output mode gives a peak output of V 2 /R watts. WAVEFORM AT A, ZERO-REFERENCED TO GROUND WAVEFORM ATE, ZERO-REFERENCED TO GROUND WAVEFORM AT E, GROUND-REFERENCED TO POINT A tion of Fig. 6, the peak available output power equals V 2 /R, where "V" is the peak available output volt- age. Note, however, that the available output power can be increased by a factor of four by connecting a pair of amplifier IC's in the "bridge" config- uration shown in Fig. 7, in which the peak available load power equals 2V 2 / R. That power increase can be ex- plained as follows: In the single-ended amplifier cir- cuit of Fig. 6, one end of R L is grounded, so the peak voltage across R L equals the voltage at point A. On the other hand, in the circuit in fig. 7, both ends of R L are " floating " and are driven out of phase; and the voltage across R L equals the difference be- tween points A and B. Figure 7 also shows some waveforms when the cir- cuit is fed with a 10- volt p-p square wave. Although the waveforms at points A and B have peaks of 10 volts relative to ground, the two signals are 180° out of phase. Therefore, during period I, point B is 10-volts positive with respect to point A. Con- sequently, if point A is regarded as the reference point, it can be seen that the point B varies from + 10 to - 10 volts between periods 1 and 2, giving a total swing of 20 volts across R L . The load in the 10-volt bridge-driv- n i: j; !0V -- •-+10V ov -10V FIG. 7 — A PAIR OF AMPLIFIERS connected in the bridge configuration gives a peak output of 2V 2 /R watts; four times the power of a single-ended circuit. When a power amplifier is con- nected in the single-ended configura- en circuit sees a total 20- volts p-p, or twice the single-ended input- voltage, > 5 O I «^ ID (C O 53 FIG. 8— INTERNAL CIRCUIT and pin connections of the LM386 low-voltage audio-power amplifier. put terminals are both ground-refer- enced, and have typical input impedances of 40K. The internal circuit of the LM386 is shown in Fig. 8. Here, Ql to Q6 form a differential amplifier in which both inputs are tied to ground via 50K re- sistors (Rl and R2) and the output of Q3 is direct-coupled to the input of common-emitter amplifier Q7. The collector signal of Q7 is direct-cou- pled to the output terminal of the IC via Class- B unity-gain power ampli- fier stage Q8-Q9-Q10 which, to mini- mize the internal volt-drops and maximize the available output power, is not provided with overload protec- tion circuitry. w o z o ir F o Q < rr FIG. 9— A MINIMUM NUMBER OF PARTS are needed for this LM386 amplifier with A v = 20. FIG. 10— LM3B6 AMPLIFIER with 6 dB of bass-boost at 85 Hz, as indicated in the diagram. Since doubling the drive voltage results in a doubling of drive current, and power is equal to the current times the volt- age (P = IV), the bridge-driven circuit produces four times more power than a single-ended circuit. LM386 basics The LM386 audio-power amplifier INPUT from o OETECTGR + V (4 TO 12VI J CI , R3 tDK VOLUME 02 -C- - V * Rl 10K C3 0022 |*F B2l C2[ B3I C3j INI (BYPASS JGAIN[GAIN 3 ' t i—i 10 H Hi 14 H 13 H 5W 4 H 12 »--- L FIG. 12— INTERNAL CIRCUIT AND PIN CONNECTIONS of the LM389 low-voltage audio- power amplifier with NPN transistor array. (manufactured by National Semicon- ductor) is specifically designed for operation with power supplies in the 4— 12-volt range. It is housed in an 8- pin DIP, consumes a quiescent cur- rent of only a few mA, and is ideal for use in battery-powered applications. The voltage gain of the IC is variable from 20 to 200 via external connec- tions, and its output automatically centers on a quiescent value of half- supply voltage. The device can feed several hundred milliwatts into a 8- ohm load when operated from a 12- volt power supply. Its differential in- FERfllTE BEAD — 1H C7 22%F 06 .047(iF M SPKH FIG. 11— AM-RADIO POWER AMPLIFIER. FIG. 13— BASIC CIRCUIT CONNECTIONS of the LM389 IC. LM386 applications The LM386 is a very easy IC to use. The voltage gain of the IC is equal to the value of the pin-l-to- pin-5 impedance (15K in Fig. 8), di- vided by the impedance between the emitters of Ql and Q3 (R5 + R6 in Fig. 8). Thus, the IC can be used as a minimum-parts amplifier with an overall voltage gain of 20 by using the simple connections shown in Fig. 9. In that circuit, the load is AC-coupled to the IC output via C2, and the input signal is connected to the non-invert- 54 ing terminal via R2. Note that CI is used to RF-decoupie the + V supply (pin 6), and R1-C3 is an optional Zobel network that gives HF output- loading stability. Note that in Fig. 9, pins 1 and 8 are not used. However, if you connect a 10-fjuF electrolytic between pins 1 and 8 (the positive end connected to pin I), you can change the overall gain of the circuit to 200; that's because the capacitor effectively shorts out the IC's internal 1.35K resistor. If a 1.2K resistor is wired in series with a 10- p.F electrolytic between pins I and 8, the overall gain will be 50. The voltage gain of the LM386 can also be varied by shunting the effec- tive value of the internal pin-5-to- pin-1 15K feedback resistor. Fig. 10 shows how to shunt that resistor with C4-R2, to give 6-dB of bass boost at 85 Hz, to compensate for the poor bass response of commonly used in- expensive speakers. Figure 11 shows how the LM386 FIG. 14— CERAMIC PHONO AMPLIFIER with tone controls, using an LM389. FIG. 15— LM389 WHITE-NOISE sound generator. BOOT BYPASS GAIN GAIN +IN STRA p A A A A A A 15K ^ -OUT 3 -ItM 1 1 — t XXX.kXX I ( 3 H 4 h 5 M '° h '1 M '2 1 ' TYTYY'i: GND FIG, 16— INTERNAL CIRCUIT and pin connections of the LM388 1.5-watt audio-power amplifier. FIG. 17— LM388 WITH A GAIN OF 20 and load returned to ground. amplifier can be modified for use as a built-in amplifier in an AM radio. Here, the detected AM signal is fed to the non-inverting input of the IC via volume-control R3, and is RF-de- coupled via RI-C3; any residual RF signals are blocked from the load via a ferrite bead. The voltage gain of the amplifier is set at 200 via C4. Note that the circuit is provided with addi- tional power-supply ripple rejection by wiring C5 between pin 7 and ground, and that the ripple-rejection capacitor can also be used with Figs. 9 and 10 if required. LM389 Circuits The LM389 (Fig. 12) contains an array of three wide-band and indepen- dently accessible NPN transistors on the same substrate as an audio- power amplifier that is almost identical to that of the LM386. The IC can be used with any power supply in the 4- to 12- volt range. The three NPN tran- sistors have closely matched charac- teristics, can be operated with collector currents in the range from 1 pA to 25 mA at frequencies up to 100 MHz, and each have typical current gains of 275. Also note that Ql, Q2 and Q3 are independently accessible. Figure 13 shows the LM389 in a basic circuit. The internal power am- plifier is used in the same way as the LM386; the gain of the amplifier is controlled by C4 and R x , between pins 4 and 12. If those two compo- nents are absent, the voltage gain is 20. If the two components are in place, and R x has a value of 1 .2K, the gain is 50. If R x is replaced with a short-circuit, the gain rises to 200. Note that the power amplifier can be used as either an inverting or non- > ID o i O 55 inverting amplifier by connecting the external signal to the appropriate in- put terminal. Figures 14 and 15 show practical applications of the LM389, making V 14 TD I2VI FIG. 18— LM388 WITH A GAIN OF 20 and load returned to + V supply. use of the internal transistors. In the phono amplifier of Fig. 14, which is intended for use with a ceramic pick- up, Q3 acts as a voltage-following in- put buffer giving an input impedance of about 80K, and Ql and Q2 are used to make an active tone -control net- work with its output feeding to the non-inverting input of the power am- plifier via the volume-control potenti- ometer. In the white-noise generator circuit of Fig. 15, Q3 is wired as a noise -generating Zener diode; the noise signal is amplified via Q2 and then fed to the inverting input termi- nal of the power amplifier, which is wired in the 200 voltage-gain mode. LM388 circuits The LM388 (Fig. 16) can be re- garded as a slightly modified version of the LM386. The device is housed FIG. 19— LM388 BRIDGE AMPLIFIER delivering 4 watts to an 8-ohm load. tn O z o cc F o < i 1 g | _w 7 , _f 3 m 4 1-, 5 H 10 H !' M 12 *— Y Y YYYYYY NX. GNO \ v <• GROUND TO HEATSfNK FIG. 20— INTERNAL CIRCUIT AND PIN CONNECTIONS of the LM380 2-wattand LM384 5- watt audio-power amplifier IC's. FIG. 21— IN THIS CIRCUIT, IF IC1 is an LM380. powered from 18 volts, the circuit will produce 2 watts, and if IC1 is an LM384, powered from 22 volts, it will pro- duce 5 watts. The circuit also has simple volume control and ripple rejection. in a 14-pin DIP with an internal heat sink, and can feed 1 .5 watts into an 8- ohm speaker when powered from a 12- volt supply. The most significant interna] difference between the LM388 and the LM386 concerns Q7, and an internal constant-current col- lector load in the LM388. That "ex- ternal load" feature greatly increases the versatility of the IC. Figure 17 shows one way of using the LM388. Here, Rl and R2 are wired in series between the positive supply line and pin 9, to provide col- lector current to the internal Q7. Note that the RI-R2 junction is bootstrap- ped from the output of the IC via C2, to raise the AC impedance of R2 (and thus the voltage gain of Q7) to a value far greater than its DC value. The overall voltage gain of the LM388 is determined in the same way as in the LM386, and equals 20 in Fig. 17. Pins 2 and 6 were not used in Fig. 17, but if you wire a 10-pF electrolytic between those two pins (with the positive end connected to pin 6), the gain can be increased to 200. Figure 18 shows an alternative way of using the LM388 where direct cur- rent (DC) is fed to pin 9 via the speak- er and Rl. Note, however, that the "low" end of the speaker is AC-driv- cn by the output of the amplifier, thereby bootstrapping Rl and provid- ing Rl with a high AC impedance. The circuit therefore gives a perfor- mance that is somewhat similar to that of Fig, 17, but does so with a saving of two components. Finally, Fig. 19 shows how to con- nect a pair of LM388 IC's in the Continued on page 84 56 PC Service AUDIO VOLUME LIMTER FOIL PATTERN. ION METER FOIL PATTERN. ■6 INCHES UNIVERSAL POWER SUPPLY FOIL PATTERN. > o i CO 8 57 Hardware Hacker LVDT position detectors Treasure finding circuitry Switcrtable analog inverter Synchronous demodulators Desktop accessories contest ^ Synchronous demodulation DON LANCASTER THIS MONTH, I FIGURED WE D LOOK AT a rather mis-named integrated cir- cuit that has an unbelievable fu- ture hacker potential. But first, as usual, let's pick up some back- ground... Programmable analog inverter Figure 1 shows you my favorite "sleeper" circuit found in my CMOS Cookbook. It's a single- ended and simple op-amp circuit that gives you a choice of a +1 or -1 gain under manual or elec- tronic control. You can analyze most any op- amp circuit by treating the (-) and ( + ) input sources separately. By a fundamental electronic law called superposition, you can get a com- bined final result. Assume that we have a fairly low- impedance input source which also provides a resistive path to ground. Suppose we close the switch; the ( + ) input sees only the resistor to ground and the (-) in- put acts as an amplifier with a gain of — 1, since the input resistor and the feedback resistor are identical. As with any op-amp, the ( - ) in- put can be treated as a virtual ground, since any deviation from the grounded (-) input will cause an output change that reaches back around through the feedback resistor to continually seek a zero difference between the ( + ) and ( — ) op-amp inputs. What if we open the switch? Well, we still have one input signal along the top that still has a gain of — 1. But now there's a new input- signal path along the bottom, which has a gain of +2. Because of CO o z o cc t- o o 5 < DC the feedback action, the ( - ) input of a properly connected op-amp will be a virtual ground "short cir- cuit," while the ( + ) input will be a high impedance "open circuit." Hmmm...the gain along the top is { —1). The gain along the bottom is +2. And, the last time I check- ed, (-D-K+2) = +1. So, close that switch and you'll get a gain of — 1. Open the switch and you get a gain of +1. Presto! A programma- ble linear inverter. Your switch can be a manual one, or else a higher-speed elec- tronic one. A quarter of a CMOS 4066 is often an ideal choice for that sort of thing. As we will shortly see, there are zillions of uses for the circuit. One obvious place is as a video inver- ter, used to create negative video images for special needs. To create a video inverter, you take the cir- cuit and add a sync separator, such as the National LM1881, and set things up to invert only your video portions but not the sync portions. Naturally, a video-quality op-amp would be needed for that use. Additional bias current can be switched in as needed to get the correct signal levels. But we'll save that for some other time, because what I really want to get into here are the secrets behind... NEED HELP? Phone or write your Hardware Hacker questions to: Don Lancaster Synergetics Box 809- RE Thatcher, AZ, 85552 (602) 428-4073 Synchronous demodulation The switch in Fig. 1 could be turned on and off at very slow rates compared to your input-signal fre- quency. Or at equal rates. Or even at much higher rates. Now, if you turn the switch on and off at pre- cisely the same speed as your in- put signal, you create a beastie that is known as a synchronous de- modulator. Synchronous demodulators form a super-important electronic concept used just about every- where. A sync demod's name can change all over the place, being otherwise known -as an autocor- rellator, a lock-in-amplifier, a doubly balanced modulator, a phase-sensitive detector, l-Q de- modulator, synchronous rectifier, a phase-locker, or, going back to some really ancient history, as a homodyne detector. Figure 1 can also be used as a modern and handy sync demod circuit. What is especially nice is that it's a single-ended circuit which needs no transformers of any kind. In general, any synchronous de- modulator demod is an electronic multiplier that extracts the sum and the difference between your input-frequency signal and your reference switching frequency. For instance, Fig. 2 shows you what happens if we keep the input and switching frequencies identi- cal, but shift their phases. Let's first assumethat ther e is a zero phase difference between signal and reference. The amplifier's gain will be ( + 1) for the positive signal peaks, and 58 ( -1) for the negative signal peaks, giving us a plain old full-wave rec- tifier. The "DC term" here will be a direct current level equal to the strength or amplitude of the input signal. The "lumps" will be a dou- ble-frequency and higher "AC term" that is usually filtered out. Thus, the zero-phased syn- chronous demodulation should extract only the amplitude of an input signal. Suppose we next shift the phase by 180 degrees. This time, your gain is (—1) for the positive lumps and ( +1) for the negative lumps of the signal. We get a negative out- put, and we could conclude that any 180 degree phased syn- chronous demodulation extracts only the negative of the amplitude of the input signal. Now, let's get interesting. Sup- pose we shift the phase to 90 de- grees. What happens? Well, nothing at all. During the time that the switch is closed, we have half of a positive cycle and half of a negative cycle, so our net (or aver- age) DC output is zero. Very hand- ily, any synchronous demodula- tion at a 90-degree phasing produces a zero output. And, since nothing upside down is still nothing, a similar cancellation happens at —90 or +270 degrees. But wait a minute. If we get zero output at a 90-degree phase, can't we double the information placed on a carrier, simply by having an in- phase term and a 90-degree, or quadrature term? We sure can, and it gets done all the time. For instance, the color informa- tion on an NTSC (Never The Same Color) television is placed onto a magic sub-carrier of 3.57545 Mega- hertz. The hue of the color is the phase angle, while the saturation of the color sets your amplitude. At the receiver, a phase-locked loop does an in-phase "I" and a quadrature "Q" demodulation. After further processing, all the separate amplitudes are extracted for the red, blue, and green guns in the display tube. Thus, we have used a pair of synchronous de- modulators to extract both the am- plitude and phase of a complex signal at the same time. Let's look at some additional uses for synchronous demodula- tion. If you hard limit the input manual or CMOS electronic switch FIG. 1— A PROGRAMMABLE GAIN AMPLIFIER. When the switch is closed, the gain is - 1. When the switch is opened, the gain is -> 1. One important circuit use is for synchronous demodulation. NAMES AND NUMBERS American Design Components 815 Fairview Ave Fairview, NJ 07022 (800) 776-3700 CIRCLE 275 ON FREE INFORMATION CARD AST Servo Systems 115 Main Road Box 97 Montviile, NJ 07045 (201) 335-1007 CIRCLE 276 ON FREE INFORMATION CARD Calogic 237 Whitney PI Fremont, CA 94539 (415) 656-2900 CIRCLE 277 ON FREE INFORMATION CARD Car Audio 2176 Oxnard Si, Ste 1600 Woodland Hills, CA 91367 (818) 593-3900 CiRCLE 278 ON FREE INFORMATION CARD Chips & Technology 3050 Zanker Rd San Jose, CA 95134 (408) 434-0600 CIRCLE 279 ON FREE INFORMATION CARD Chomerics 77 Dragon Court Woburn, MA 01888 (800) 225-1936 CIRCLE 280 ON FREE INFORMATION CARD Linear Technology 1630 McCarthy Blvd Milpitas, CA 95035 (408) 432-1900 CIRCLE 281 ON FREE INFORMATION CARD Measurement & Control 2994 W Liberty Ave Pittsburgh, PA 15216 (412) 343-9666 CIRCLE 282 ON FREE INFORMATION CARD I CARD I Midnight Engineering PO Box 7041 Fort Collins, CO 80525 (303) 491-9092 CIRCLE 283 ON FREE INFORMATICS Motorola 5005 E McDowell Rd Phoenix. AZ 85008 (602) 244-6900 CIRCLE 284 ON FREE INFORMATION C ; ! National Semiconductor 2900 Semiconductor Dr Santa Clara, CA 95051 (408) 721-5000 CSRCLE 285 ON FREE INFORMATION CARD OrCAD 3175NWAIoclekDr Hillsboro, OR 97124 (503) 690-9722 CIRCLE 235 ON FREE INFORMATION CARD Phillips 45 George Washington Hwy Midfield, Rl 02917 (401) 232-0500 CIRCLE 287 ON FREE INFORMATION CARD Sensors 174 Concord St Peterborough, NH 03458 (603) 924-9631 CIRCLE 288 ON FREE INFORMATION CARD Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 CIRCLE 289 ON FREE INFORMATION CARD Texas Instruments PO Box 809066 Dallas, TX 75380 (800) 232-3200 CIRCLE 290 ON FREE INFORMATION CARD > O I CD CD O 59 signal to your sync demod so that it's a clean square wave, then you will provide phase detection. Co through the math, and you will find that the output voltage is a triangle which linearly equals the phase angle between the input and the reference. You can then use your sync demod to measure the phase angle between two in- put signals. Suppose we would syn- chronously demodulate one sig- nal and, at the same time, apply an interfering signal of a different fre- quency. Your "wanted" signal will always be in phase and will always produce a DC output equal to its amplitude. The "unwanted" signal will create a sine wave as it "slips cycles" with respect to the wanted one. Any sine wave averages to zero over a long enough time. We apparently have a way of detecting one signal while rejecting an inter- fering one. Certain types of sync demods are called lock- in amplifiers. They can form an extremely narrow bandpass filter that automatically o z o cr t- o HI -J LU 6 Q < cr NEW FROM DON LANCASTER HANDS-ON BOOKS Hardware Hacker Reprints II 24.50 Ask The Guru Reprints I or II 24.50 CMOS Cookbook 18.50 TTL Cookbook 16.50 Active Filter Cookbook 15.50 Micro Cookbook vol I or II 16.50 Enhancing your Apple I or II 17.50 AppleWrlter Cookbook 19.50 AppleAssemblyCookbook 21.50 Incredible Secret Money Machine 10.50 LaserWriter Reference (Apple) 19.50 PostScript Cookbook (Adobe) 16.50 PostScript Ref. Man. (Adobe) 22.50 PostScript Prog. Design (Adobe) 22.50 Heal World Postscript (Roth) 22.50 UNLOCKED SOFTWARE LaserWriter Secrets (lle/Mac/PC) 29.50 PostScript Show & Tell 39.50 Intro to PostScript VHS Video 39.50 PostScript Beginner Stuft 39.50 PostScript Perspective Draw 39.50 PostScript Technical Illustrations 39.50 PostScript Work In Progress 39.50 PostScript BBS stuff 19.50 Absolute Reset He & lie 19.50 AppleWrlter/Laserwriter Utilities 49.50 Enhance I or II Companion Disk 19.50 AppleWrlter CB or Assy CB Disk 24.50 FREE VOICE HELPLINE VISA'MC SYNERGETICS Box 809-RE Thatcher, AZ 85552 (602) 428-4073 CIRCLE B3 ON FREE INFORMATION CARD INPUT INPUT REFERENCE OUTPUT INPUT INPUT REFERENCE OUTPUT ^W REFERENCE i I 1 1 L OUTPUT /VWN A VW\ V REFERENCE A 1 1 1 1- 0UTPUT WW Whan the reference and (he signal are in phase (0 degrees), a strong dc term is produced that is proportional to the strength of the input signal. The second harmonic and higher ac frequencies are usually strongly filtered out, leaving only a dc term. When the reference and the signal are in quadrature (90 degrees), a zero dc term is produced, completely rejecting the input signal. Values very near a quadrature or 90 degree phase are often used for phase measurements or for FM demodulation When the reference and the signal are out of phase by 180 degrees, a strong negative dc term is produced Ehat is proportional to the input signal. Note that the circuit of figure one is 180 degree phased, unless you purposely invert the reference input signal. M N\N K When the reference and the signal are at -90 or +270 degrees, a zero dc term is produced, once again completely rejecting the input signal. Because of quadrature rejection, twice as much information can be put onto a synchronously demodulated carrier. FIG. 2— SYNCHRONOUS DEMODULATOR WAVEFORMS. At degrees reference phasing, the "DC" portion of the output is proportional to the input amplitude, and interfering signals are strongly rejected. At 90 degrees, the "DC" portion is zero, and the input signal itself gets strongly rejected. centers on the frequency of inter- est, and can yield tremendous im- provements in signal to noise ratios, As an example, it is not un- known for your lock-in amplifier to cleanly extract a signal that is buried in noise that can be as muchas120decibelssfrongerthan the signal you want. Important uses here include extracting data from deep-space probes, and doing any laboratory and medical instrumentation that measures very weak signals in the presence of much larger interfering noise and AC hum. A not-quite synchronous de- modulation will output a sine wave equal to the difference between the reference and input frequen- cies. That is a simple example of a downconverting, or mixing of one signal against another to get a fre- quency difference. By using a pair of sync demods, you can not only extract the fre- quency difference, but also deter- mine which of the frequencies are higher. The doppler signal extraction in a side-looking radar is one major use. Separately, synchronously demodulating a shaft encoder can give you both speed and direction information. Flangers for elec- tronic music synthesizers use a similar principle. 60 PRINTING RESOURCES American Printer 29 N Wacker Drive Chicago, 11 60606 (312) 726-2802 CIRCLE 291 ON FHEE INFORMATION CARD Font & Function PO Box 7900 Mountain View, CA 94039 (800) 833-6687 CIRCLE 292 ON FREE INFORMATION CARD Graphic Arts Monthly 249 W 17th Street New York, NY 10011 (212) 463-6834 CIRCLE 293 ON FREE INFORMATION CARD Graphic Arts Product News 29 North Wacker Drive Chicago, IL 60606 (312) 726-2802 CIRCLE 294 ON FREE INFORMATION CARD High Volume Printing Box 368 Northbrook IL, 60065 (312) 564-5940 CIRCLE 295 ON FREE INFORMATION CARD In-Plant Printer Box 368 Northbrook, IL 60065 (312) 564-5940 CIRCLE 296 ON FREE INFORMATION CARD In Plant Reproductions 401 North Broad Street Philadelphia, PA 19108 (215) 238-5300 CIRCLE 297 ON FREE INFORMATION CARD Instant Printer Box 368 Northbrook, IL 60065 (312) 564-5940 CIRCLE 298 ON FREE INFORMATION CARD Print Equipment News Box 5540 Glendale. CA 91221 (818) 954-9495 CIRCLE 299 ON FREE INFORMATION CARD For a really strange use of a sync demod, high-power rectifiers al- ways have a forward drop associ- ated with them of a volt or more that can cause all sorts of ineffi- The Printers Shopper PO Drawer 1056 Chula Vista, CA 92012 (800) 854-2911 CIRCLE 300 ON FREE INFORMATION CARD Printing Impressions 401 North Broad Street Philadelphia, PA 19108 (215) 238-5300 CIRCLE 301 ON FREE INFORMATION CARD Printing Journal Box 91447 Pasadena, CA 91109 (818) 793-7901 CIRCLE 302 ON FREE INFORMATION CARD Printing News 245 W 17th Street New York, NY 10011 (212) 463-6727 CIRCLE 303 ON FREE INFORMATION CARD Publishing Technology 401 North Broad Street Philadelphia, PA 19108 (215) 238-5300 CIRCLE 304 ON FREE INFORMATION CARD Quick Printing 1680 SW Bayshore Blvd Port St Lucie, FL 34984 (407) 879-6666 CIRCLE 305 ON FREE INFORMATION CARD Screen Printing 407 Gilbert Avenue Cincinatti, OH 45202 (513) 421-2050 CIRCLE 306 OH FREE INFORMATION CARD Type World 15 Oakridge Circle Wilmington, MA 01887 (617) 658-6876 CIRCLE 307 ON FREE INFORMATION CARD U&lc 2 Dag Hammarskjold Plaza New York, NY 10017 (212) 371-0699 CIRCLE 308 ON FREE INFORMATION CARD ciencies, especially with low-volt- age solar-panel power con- versions. 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Foreign epfllieanls will receive specie! ordering instructs. Cande musr fpmil m U.S. currency. This order subject to acceptance by Ihe Electronics Book Club . RE390 3 > 33 O I to (D O 65 EARN YOUR B.S.E.E. DEGREE THROUGH HOME STUDY Our New and Highly Effective AcJvanced-Plaee- ment Program for experienced Electronic Tech- nictans grants credit for previous Schooling and Professional Experience, and can greatly re- duce the lime required to complete Program and reach graduation. No residence schooling re- quired for qualified Electronic Technicians. Through this Special Program you can pull all of the loose ends of your electronics background together and earn your B.S.E.E. Degree. Up- grade your status and pay to the Engineering Level. Advance Rapidly! Many finish in 12 months or less. Students and graduates in afl 50 States and throughout Ihe World. Established Over 40 Years! Write for free Descriptive Lit- erature. COOK'S INSTITUTE OF ELECTRONICS ENGINEERING £Sgl'W E 4251 CYPRESS DRIVE V-*^E JACKSON, MISSISSIPPI 39Z12 CIRCLE S8 ON FREE INFORMATION CARD 18000 *#* ELECTRONIC COMPONENTS Whether you order t part or all 18,000+ . . . MQUSER stocks to meet your needs and ships when you need it most . ... today It MQUSER also makes it easy to do business Monday g Q < DC 66 MOUSER ELECTRONICS Seles & Stocking Locations Nationwide • ■•« • *•* *•** «*** *•** SCHEMATIC (B) CROSS SECTION (-) cor» position (+) (C) RESPONSE FIG. 3— LINEAR VARIABLE DIFFERENTIAL TRANSFORMERS, or LVDT's for short, can be used for extremely precise position-to-vottage transducers. The output voltage Is propor- tional to the core position. Microweighing is one use. FIG. 4 — THE PHILLIPS SIGNETICS NE5520N has an internal precision sine-wave gener- ator, a sync demod. and an extra op-amp that gets used here as an output filter. This is how to apply it as an LVDT signal conditioner. Since the chip can do so much more, it does seem a shame to waste it on LVDT uses. overdriven as a switch. To improve the efficiency of a solar power con- version system, you create a synchronous rectifier that uses a sync demod and a pair of power transistors to replace your ineffi- cient power diodes normally used. Finally, one early way of detect- ing an AM radio station was known as a homodyne detection. Here you would synchronously demod- ulate your incoming signal against a reference of the same frequency as the transmitter carrier and then directly extract your audio in a sin- gle step. Unfortunately, they howled a lot as they were tuned and tended towards instability, so they were flushed in the Iate1920's in favor of superheterodyne cir- cuits that used intermediate fre- quency amplification, often at 455 kilohertz. Today, the old homo- dyne deserves a fresh new look, especially when combined with digital synthesis, and the ability to put highly stable audio gain and good filtering into very small pack- ages. So, sync demods are easy to build and can be amazingly ver- satile. But, before we explore a great sync demod chip and mor real-world uses, let's briefly look at some little-used hacker compo- nents known as... LVDT's An LVDT, or a Linear Voltage Differential Transformer, is shown in Fig. 3. An LVDT is a transformer which has a movable core, a single winding on the primary, and a pair of secondary windings. The sec- ondary windings are connected in opposition, so that the output CIRCLE 117 ON FREE INFORMATION CARD \ voltage will be the difference be- tween the two. When the movable core is in the center, equal and opposite volt- ages are induced in the second- aries, and the output voltage is zero. As your core moves up, a 0- degree phased sine wave appears in your output. As it moves down, a180-degree phased sine wave ap- pears instead. With careful design, you can get a linear sine-wave output voltage whose amplitude changes with position, and whose phase is (0) degrees for positions above center and (180) degrees for positions be- low center. In short, an LVDT is a very pre- cise and ultra-sensitive position- to-voltage transducer. Some LVDT devices can easily sense any mo- tions or position changes as small as a thousandth of an inch or less. They can also be made large enough to measure distances of severai feet or more. Unfortunately for hackers, LVDT's are rather pricey, since they are both low-volume and preci- sion components. One useful sur- plus source is AST Servo, while others advertise in the Sensors and Measurement and Control trade journals. Several LVDT uses? Weigh scal- es, especially for microweighing; torque sensing; accelerometers; distance measurement; in- clinometers; pressure trans- ducers; for seismometry; load cells; micropositioners; and any- where else where you want to con- vert a very small motion or distance change into a useful elec- trical signal. For precision results, your LVDT must get driven from a pure audio sine wave of a fixed and known amplitude. Distortion could lead to bad harmonics which will in turn create output errors and other difficulties. To further up the LVDT preci- sion, you can use an LVDT in its servo mode. Here, you'd use feed- back to move, balance, shove, or otherwise continually coerce the LVDT back to its null position. That is known as null seeking and, be- cause of the feedback, many non- linearities can be greatly reduced if not canceled outright. lol Descrambler Article Farts We stock the exact parts, PC Board and AC Adaptor for two articles published in Radio-Electronics magazine on building your own CABLE TV DESCRAMBLER February 1987 issue #301 Parts 29.00 Includes oil original parts. #302 PC Board 7.95 February 1984 issue #701 Parts 19.00 Includes all original parts. #702 PC Board 7.95 Original 3x4 etched, drilled and silk-screened pc board. #704 AC Adaptor 7.95 Original 18 Volt DC 9 200ms. #701, 702 & 704 29.00 Original 5x8 etched, drilled and silk-screened pc board #304 AC Adaptor 7.95 Original 18 Volt DC m 200ma. #301, 302 & 304 39.00 Free article reprint with purchase. Snooper Stopper 39.00 Cable TV de scramblers can be detected, protect your privacy with the Snooper Stopper. Free article on Cable Snooping. Macrovision Kit 29.00 nucrovisian now you see it, now you don't wilh our macroscrubber kit. Article was published in Radio Electronics 1987 issue. Visa CALL TOLL FREE 1-800-332-3557 Out side USA 1-508-699-6935 Visa, Master Card and COD. Add 13.50 S & H, S6.00 outside USA. D S. D Electronics, Inc., PO Box 3310, N Attleboro, ha 02761 MC CIRCLE 187 ON FREE INFORMATION CARD While LVDT's are usually super- precise, there's no reason you can't throw one together on your own to create a low-cost position sensor. Be sure to let me know what you do come up with on that. By another of those astounding coincidences that infest this col- umn, it looks like we need a sync demod to extract the position info from an LVDT. But, if we have a simple and cheap circuit that does that, why limit it to LVDT uses, when so much more can be done so much better with it? Which brings us around to... The misnamed chip Sometimes a manufacturer might simply put the wrong name on one of their integrated circuit chips. For instance, which of these two has the greater hacker poten- tial : a Signetics NE5520N LVDT Sig- nal Conditioner, or a Phillips NE5520N Universal Single Chip Treasure Finder? As you might guess, Signetics is Phillips and, of course, the NE5520N is the NE5520N. Figure 4 shows details. What we have is a u; \ic\ vck CLEANING/MAINTENANCE/REPAIR EARN UP TO $1000 A WEEK.WORKING PART TIME FROM YOUR OWN HOME! THE MONEY MAKING OPPORTUNITY OFTKE1990'S IF you are able to work with common small hand tools, and are familiar with basic electronics (i.e. able to use voltmeter, understand DC electronics). . . . IF you possess average mechanical ability, and have a VCR on which to practice and learn. . . .then we can teach YOU VCR maintenance and repair! FACT: up to 90% of 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! Viejo's4D0 PAGETRAINIHG MANUAL (over 500 pho- tos and illustrations) and AWARD-WINNING VIDEO TRAINING TAPE reveals the SECRETS of VCR mainte- nance and repair— "real world" information that is NOT available elsewhere! Also includes all the info you'll need regarding the BUSINESS-SIDE of running a successful service op- eration! FREE | HF0RHAT | 0N CALL TOLL-FREE 1-800-537-0589 Or write to: Vieju Publications Inc. 3540 Wilshire BL. STE. 310 Los Angeles, CA 90010 Dept. RE CIRCLE 184 ON FREE INFORMATION CARD > O I CD 5 67 **** iili • ••■ • *#* • ••* • ••■ n ■••• tftf ■ *•« • •** • **« • *#* ■ ■** • **• ■ ■•• FIG. 5— THE SENSING HEAD of an induction-balance treasure finder or a metal locator can be thought of as an LVDT in disguise. The target acts as a movable core. Synchronous demodulation can separate metal from mineral detection. precise amplitude and low-distor- tion audio sine-wave generator, a synchronous demodulator, and one uncommitted op-amp you can use for output filtering, meter driving, or in-phase to quadrature conversions. The circuit shows you how to power and sense the output of an LVDT. While you actually could use one of those chips with an LVDT, the beast should work well for an extremely wide variety of hacker stuff. Where else could we use an audio source and a sync demod? One place could include modu- lated infrared alarms and commu- nicators that can ignore both sunlight and room lighting, A sec- ond might be in the fluxgate mag- netometer used in solid-state digital compasses. How about treasure finding? I can think of at least a dozen uses here. Figure 5 shows us how the search head of an induction bal- ance metal locator is really an LVDT in disguise. In the absence of a buried ob- ject, the voltages induced into the « output sensing coils are equal and z opposite. A buried ore or a metal § object will distort the transmitted £5 field, and unbalance the output y voltages. JV Now for the neat part; any "met- 5 al" objects return an in-phase S component to the output signal, while "mineral" deposits, such as a well-rusted can, returns us a quadrature signal. Nicely separat- ing the goodies from all the grunge and garbage. Thus, the NE5520N circuit can be used for in-phase discrimina- tion of metal objects, or for quad- rature discrimination of mineral objects. To do the quadrature syn- chronous demodulation, just shift the phase of your reference by 90 degrees. Add a second NE5520N, and you can also add such ad- vanced features as automatic ground tracking and the "native" soil background cancellation effects featured on the higher priced locators. Similarly, over in those receiver- transmitter styles of metal locators often chosen for pipe finding, fi- ber optics can be used to optically couple from the transmitter to the receiver, minimizing any field dis- tortions an actual cable might create. A sync demod at the re- ceiver could then be used for im- proved sensitivity and for metal/ mineral discrimination. The NE5520N costs around $7 in smaller quantities. Supply current is around seven milfiamperes, easily provided by a 9-volt battery. While you can run the chip at +5 volts, its stability will not be as good. For additional NE5520N circuit details and bunches of applica- tions info, seethe Industrial Linear Data Manual II offered by Phillips. Check out the NE5521N as well. Printing resources As you know, each month I try to feature a Resources Sibebarwh'ich shows you where to go for the real insider stuff on unusual topics of hardware hacking interest. Sources that are difficult or impos- sible to quickly pin down on your own. Be sure to tell me what you want to see in future sidebars. This month's sidebar gives you a rundown of the major sources of information on printing and printshops. What does that have to do with hardware hacking? Just this: there's a total desktop-pub- lishing revolution going on out there, and traditional printing equipment and machinery is so utterly and outrageously priced that it simply won't hack it. What we need instead is for all you hackers to come up with low- cost and low-end, do-it-yourself hardware kit solutions for desktop printing and book-on-demand publishing needs. To do that, hacking skills and a hacker men- tality are essential. And the oppor- tunities are pretty nigh unlimited. What's needed? Well, for openers, here's a tiny part of my wish list: (1) A low-cost Kroy Kolor machine that doubles as a laminator and as a printed circuit direct-toner trans- fer processor. (2) A true perfect binder that gives fully professional cold-glue results for under $99. (3) A sanely priced clamping paper cutter which can accurately trim 200 sheets at a time. (4) A die punch that, in one whomp, cuts out twelve business cards from a single sheet of cover stock, (5) A low-cost padding press. (6) An economical and program- mable folder. (7) A simple-to-use pad printer for the "real" printing of pens, golf balls, mugs, keyholders, and such. (8) A cheap corner rounder. (9) A workable paper drill. (10) Automated conversions from Continued on page 78 NEW FROM ETT O TELE— THE INVEN- TION OF TELEVISION $9.95. How television came to be. Packed with history. 36-pages o\ photos and il- lustrations of early equip- ment A collectors delight. D PCP105— MAKE MONEY FROM HOME RE- CORDING $10.00. Now that you've spent a fortune on all that recording gear, MIDI and all, wouldn't you like to get some of It hack? This booh shows you how. 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Box 240 Massapequa Park, NY 11762-0240 SHIPPING CHARGES IN USA AND CANADA $30.01 to $40.00 S5.00 $40.01 to $50.00 $6.00 $50.01 and above S7.50 $0.01 to $5.00 ...$1.25 $5.01 to 10.00 ,..$2.00 $10.01 to $20.00 $3.00 $20 01 lo S30.00 S4.00 SORRY, No orders accepted outside of USA and Canada Total price of merchandise $ Shipping (see chart) $ Subtotal S Sales Tax (NYS only) t Total Enclosed $ Name. Address . City .State . -Zip- POWER SUPPLY continued from page 34 nate in a row on one end of the PC board. Figure 4 shows the general chassis layout, and Fig. 5 shows the juncture between the PC boards and the custom heats ink close up. Use 1 6- gauge or heavier wire for the leads to JI-J4. and twisted pairs to RB-RI4 and R15-R16. If you're including the 5-volt supply, install BR3, CIO, CI 1, and IC3 with the secondary heatsink using point-to-point wiring. Connect Tl, wire the primaries, and mount the primary heatsink and front panel. You should now be ready to turn on the supply. Checkout Install Fl and F2, apply power, and check for + 60 volts DC across CI and C2. Check for a bias supply of — 25 volts DC across C3. Vary R15 and R16, and observe the output voltage change. When the current limiter is fully counterclockwise, the output voltage may be zero, regardless of adjustments. When current limiting occurs, LED1 should glow. R-E Choose from 33 — Career Opportunities Get Your Specialized Associate Degree or Career Diploma at Home in Spare Time Now without attending college classes and with no previous experi- ence, you can train for a money- making career ..ever get a degree. Send for free facts and color bro- chure or employment opportuni- ties in the field that interests you most. See how easy it is to train at home for a great new career or advancement on your present job. H^ 1-800-228-5300 Mimr CALL ANVT IME— Operator! to lake your call Dept. DES20 24 hour* a day. 7 days a week. Ho coir No oblivion Ho salesman will visit. _PS. M ^ [ LF2. u £?li. 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Merrick Rd Valley Stream NY 11680 Unconditional 30 days Money Back Guarantee CIRCLE 97 ON FREE INFORMATION CARD CABLE TV DESCRAMBLER lUnit 10 + Jerrold S.B $74 $55 Jerrold SB w/Trimode $90 $70 Oak N-12 (WVS) $89 $65 Scientific Atlanta $109....$75 Pioneer $109....$75 Panasonic converter $98 $79 73 channel converter $79 $59 We Beat Anyone's Price! 30 Days Money Back Quaranty Free Catalog Visa, M/C, COD or send money order to: US Cable TV Inc. Dept.KAi 4100 N.Poweiiine Rd„ Suite F-4 Pompano Beach, Fl 33073 1-800-445-9285 Please have make and model number of the equipment used in your area ready. No Florida Sales! It's not the intent of US Cable TV Inc. to defraud any pay TV operator and we will not assist any company or individual in doing so. CIRCLE 198 ON FREE INFORMATION CARD > D O I to O 69 HPSS ■■ msm RE Engineering Admart 6805 MICROCOMPUTER DEVELOPMENT SYSTEM The MGPM-1 system allows the IBM PC and compatibles lo be used as a complete development system for the Motorola MC68705P3. P5, U3, U5. R3 and H5 single chip microcomputers. The system includes a cross assembler program, a simulator/debugger program and a programming hoard that connects to a serial port. Price— $449.00 VISA and MASTERCARD accepted. ' THE [»SI*F£SS ' CBUtBBSiTlfl. IMC RR#3, BCK 8C Barton, Vermont 05822 Phone C802) 525-3458 fV0( (802) 525-3451 Rates: Ads are 2W" x 2 7 /a". One insertion $950. Six insertions $925. each. TWelve insertions $895. each, Closing date same as regular rate card. Send order with isttance to Engineering Admart, Radio Electronics Magazine, 500-B Bi-County '., Farmingdale, NY 11735. Direct telephone inquiries to Arline Fishman, area -516-293-3000. Only 100% Engineering ads are accepted for this Admart. FCC LICENSE PREPARATION The FCC has revised and updated the commercial license exam. The NEW EXAM covers updated marine and aviation rules and regulations, transistor and digital circuitry. THE GENERAL RADIOTELEPHONE OPERATOR LICENSE - STUDY GUIDE contains vital Information. VIDEO SEMINAR KITS ARE NOW AVAILABLE. WPT PUBLICATION 979 Young Street, Suite A Wood burn, Oregon 97071 Phone (503) 981-5159 MIDI Project! MIDI PROJECTS BP182— MIDI interfacing enables any so equipped instruments, regardless of the manufacturer, to be easily connected to- gether and used as a system with easy com- puter control of these music systems. Combine a computer and some MIDI instru- ments and you can have what is virtually a programmable orchestra. To get your copy send 56.95 plus $1.25 for shipping in the U.S. to Electronic Technology Today Inc., P.O. Box 240, Massapequa Park, NY 11762-0240. ILE 195 ON FREE INFORMATION CARD CIRCLE 18S ON FREE INFORMATION CARD ION METER continued from page 38 O BE o LU o < move the detector rod with ease; it should fit snugly into J3. Assembly Mount S2, R5 and R7 on the front panel. Prewire SI before mounting it, since access after mounting the PC board is difficult. Leave enough lead length to mount the PC board and SI without strain. Install two metal PC- board standoffs on the back of the front panel, and connect Ml to the PC board. Mount the PC board on the standoffs, and install SI. Use solder lugs between the mounting screws and the PC board as grounds. Wire the power leads to S2 , making sure that the PC board + 5-volt DC lead goes to the center terminal. Switch S2 is an SP3T version, so the up position connects to BI, and the down position to 1C2. Solder two wires from the PC board to R5, the balance control; the orientation doesn't matter, since that's just a fine adjustment for R8. Solder the positive battery lead to the bottom terminal of S2, and the negative lead to the upper ground lug. Solder two leads to sen- sitivity-control R7 so that it's shorted when fully clockwise. Install shoulder washers in the two 'A-inch detector-screen mounting holes and use #6 screws to attach the detector-screen L-brackets. Also, sol- der one end of Rl to J4, and the other end to the upper PC-board ground iug. If you can't find any shoulder washers to insulate the detector screen from the case, use (4-inch plastic grommets in the case mounting holes. Attach the 9-volt-battcry clip to the left rear of the bottom surface with a W-inch #4 screw. Mount IC2 in the case hole shown in Fig. 4-c, using a TO-220 insulator kit. Solder R13 between the out and gnd pins. Solder Rl2 from the IC2 gnd pin to the lower PC-board ground lug. Solder the positive side of C17 to the in pin of IC2 , and the other end to the lower ground lug. Solder a wire to the out pin of IC2, and the opposite end to the upper terminal of S2. To avoid attaching Jl to the rear of the box and preventing its removal, ce- ment it to the right rear edge. Connect a wire from the "tip" terminal to the in pin of IC2, and from the "sleeve" terminal to the lower ground lug (see Fig. 3). Checkout Set R7 fully clockwise, R5 to cen- ter, SI to positive, and turn on S2 using either Bl or IC2. With a high- input- impedance multimeter, the volt- age from the detector screen to the case should be + 35^45 volts DC. Switch SI to negative, which should give -35-45 volts DC. If no voltage is present, check with an ohmmeter for a short from the detector screen to the case. Check pin 8 of IC1 for 9- volts DC, and pin 3 for 20 kHz. A small AM radio tuned to either end of the broadcast band should pick up har- monics when physically close to ICl. When you turn the ion meter on. Ml should be nearly centered, and rotating R7 should swing the needle left or right; adjust for full scale either way. Next, adjust R8 until Ml is cen- tered. Repeat until R7 is fully clock- wise, and Ml is centered; that represents maximum sensitivity for positive ions. Then, set SI to nega- tive; Ml should deflect sharply to one side, so reduce sensitivity, rotating R7 counterclockwise until Ml fully de- flects. Adjust R8 for center balance with full sensitivity as before; that represents maximum sensitivity for negative ions. The ratio of negative to positive ions constantly changes. Thus, to bal- ance both positive and negative read- ings at the center of Ml with full sensitivity is almost impossible. The ion meter reacts only to the immediate ion population. To balance the ion meter, adjust R7 and R8 until equal readings on each side of zero are obtained for both set- tings of SI. They may or may not be full scale, but should be adjusted to be within scale using R7. When the ion polarity under observation is changed by switching SI, the detector takes about 20 seconds to stabilize, by bleeding off ions of opposite polarity. A little readjustment of balance vs. sensitivity should let you zero the ion ratio for both polarities . a basic refer- ence level. When adjusted, carry the ion meter rapidly from room to room, and watch Ml swing. R-E 70 ComputerDigesi ESS ENT&Y iYSTEM fnfnrwtfinjiH 5/ fe Mo 3ra/a popular 68705 microcontroller. Keyless entry systems have long been commercially available, but the costs associ- ated with the systems usually preclude their use in homes and small businesses. However, by using a readily available and in- expensive microcontroller, a full- featured digital keyless entry sys- tem can be built from just a handful of components at a frac- tion of the cost of commercial units. The digital keyless entry sys- tem presented in this article is a simple yet highly flexible design requiring approximately a dozen components. It costs less than $75, most of which (about $45, depending on where you get it) goes for the electromechanical door latch. STEVEN AVR TCH ,\ How it works The digital keyless entry sys- tem consists of three major com- ponents: the microcontroller, a keypad, and the electromechan- ical door latch (see the block di- agram In Fig. 1). To unlock the door, the user simply punches a three-digit en- try code on the keypad. The mi- crocontroller compares that code with the valid codes stored in its battery-backed RAM. If it matches, the latch is energized, and the door may be opened. In a power failure, the user can by- pass the code-entry scheme and open the door with a key The keyless entry system may be programmed to recognize three distinct entry codes, each continued on page 74 LED INDICATOR □ n ^ — ,o- — [HCDlI] mscu tntnco MICROCONTROLLER ELECTROMECHANICAL DOOR LATCH KEYPAD Fig. 1. A 68705 MICROCONTROLLER accepts keypad input and then energizes an electromechanical door latch after the proper entry code has been entered. EDITOR'S WORK- Bench Boot from ROM Industrial controllers typically suffer from lack of a standard development environment — or, if one is available, it's expensive. The PC is ubiquitous; why not use it to develop real-time control systems? One reason is cost: a full-blown PC may be too expensive for field use in many applications. Even if cost is not a major consideration, another problem is reliability; disk drives (hard or floppy) typ- ically don't fare well in industrial environments. Of course, disk drives aren't absolutely required; there are diskless LAN workstations, and some laptops boot from DOS in ROM. But putting DOS in ROM requires special expertise with device drivers and BlOSes— or does it? It doesn't have to; Annabooks (the company famous for selling a C-language BIOS in source- code form) has done all of the dirty work for you. With their PROMKIT you insert the diskette to be emulated in a disk drive, run a one-line batch file, burn the resulting code into EPROM, and you're done. How it works s When a PC with a standard 33 BIOS boots, it scans the memory § area above the video adapters g (C000;0000— EOOO:FFFF) look- 8 71 if) o z o en h- u NOTES: THIS BOARD USES TWO Z7S12 PROMS AT SEGMENTS OXXXX AND EXXXX FOR 128K DRIVE ON XT TYPE MACHINES. SOME AT MACHINES MAY ALLOW ONLY 64K TO BE USED. ing for the "signature" word 55AAh every 2K. If the scan rou- tine finds the signature, it picks up the third byte, which specifies the number of 512-byte blocks contained in the routine. The maximum value of the size byte is FBh (251), allowing a total of just under 128K {251 x 512) bytes. The scan routine next computes a checksum over the specified number of blocks. If the check- sum equals zero, the BIOS then executes a far call to the fourth byte, which is where user code should start. The user code should perform its initialization and then terminate with a far re- turn, which will allow the scan routine to continue at the next available block. There's nothing magic or even particularly obscure about that procedure: IBM has used it at least since the introduction of the XT, whose hard-disk control- ler contains a BIOS extension al- lowing orderly access to one or two hard disks. The same tech- nique is used by EGA and VGA video cards, network adapters, even some "intelligent" floppy- disk controllers, and more. CSl 20 cso :CD* Try the Electronics bulletin board system (RE-BBS) 516-293-2283 The more you use it the more useful it becomes. We support 300 and 1200 baud operation. Parameters: 8N1 (8 data bits, no parity, 1 stop bit) or 7E1 (7 data bits, even parity, 1 stop bit). Add yourself to our user files to increase your access. Communicate with other R-E readers. Leave your comments on R-E with the SYSDP. RE-BBS 516-293-2283 3 > x a o 73 KEYLESS ENTRY continued Jrom page 71 of which consists of three digits. You change the entry codes from the keypad by entering a special three-digit "function" code, dis- cussed in detail later. An LED in- dicates system status. It should be noted that the digi- tal keyless entry system is not a complete security system in and of itself; however, it can function as an integral component of a complete security system. ED m lh m m co CD CD CD □ LD [D KEYPAD FACE Circuit description The heart of the system is the Motorola MC68705P3 micro- controller discussed in detail in the September 1989 Radio- Elec- tronics (page 82). Tb summarize its features, the microcontroller has 64 bytes of RAM. 2K of EPROM, a built-in clock os- cillator, and 20 I/O ports. You can program the 68705 with some off-the-shelf EPROM programmers; you may also want to consider building the pro- grammer described in the earlier article. common grodno type Fig. 2. THE KEYPAD consists of Jour rows by three columns. Pressing a key grounds the intersection of the corresponding row and column. The keypad used in this design is a standard four-row by three- column keypad with a common ground, as shown in Fig. 2. Each of the seven keypad outputs is pulled up by a resistor (R1-R7) and is connected to ports AO— A6 of the microcontroller, as shown in Fig. 3. The microcontroller uses a software scanning routine to determine when a key is pressed. When the microcontroller has recognized a valid entry code, it sends port PBO high, which turns on power MOSFET Ql, which in turn enables relay RYL Current for the door latch then flows through the relay contacts. Diode Dl is wired across the coil of the relay to prevent voltage spikes caused by the in- stantaneous change in current through the relay coil. Port B7 of the microcontroller drives LED1 (status) directly. A logic low on port B7 completes the circuit to ground and lights the LED. When the extal and xtal inputs (Dins 4 and 5) are connected to- Fl WAMP II7VAC E3» 1D-14VAC RECTIFIER & FILTER I9JVDC i -t— 03 1N4W1 .-J 9.0 VDC WALL TRANSFORMER 00 O Z o cc h- o W s < or. OUT GND C3 l»iF D4 IN4001 6V BATTERY COMMON GROUND TYPE KEYPAD lOOnF 10V W Jl H m a R1-R7 33K CDLI C0t! ROW 1 ROW 2 ROW 3 ROW 4 COL 3 Fig. 3. COMPLETE SCHEMATIC ojthe digital keyless entry system. You can eliminate diode D4—D7 if you don't want battery backup. However, you'll be limited to the access codes burned into the microcontroller's EPROM. 74 Resistors ^^^— ^^^^^^ AH resistors are 'A-watt 5%. unless otherwise noted. R1-R7 33.000 ohms RS 470 ohms R9 20.000 ohms Capacitors i ci i uF. 10 volts. electrolytic C2 100 uf. 10 volts. electrolytic C3 O.J p.F. ceramtc disc Semiconductors ^^^m«m ICl MC68705P3 microcontroller IC2 7805, 5-oollDC regulator gi JKF5JJ. power MOSFET LED1 standard red D2-D7 1N4001. 100 volts, 1 amp Miscellaneous wmm^m^^mm——m Keypad common ground Door latch (see text) Relay SPST. 5-uolt coil . 50 ohms, 100 mA Fuse J/2 amp (and holder) Transformer 9-volt DC. wall- mount Batteries 4 AAcells (and holder) Ordering Information The following are available from Simple Design Implementations (SDI) P.O. Box 9303 Forestville, CT. 06010 programmed & tested MC68705 $25 + $2.50 S/H Electromechanical door Latch $45+$4 S/H) Complete kit of parts as shown in Parts List ($75 + $6 S/H) Software on 5.25" disk ... $25 + $3 gether as shown in Fig. 3, the microcontroller's internal os- cillator circuit runs at about 800 kHz, providing a cycle time of about 1.25 |j,s. The accuracy of a crystal oscillator is not important for this project. The microcontroller pulls up the reset input (pin 28), thereby eliminating the need for an exter- nal resistor. The l-|i.F capacitor (CI) connected from that pin to ground gives the power supply time to stabilize before allowing the microcontroller to start up. The external-interrupt input (Int. pin 2) is tied high because interrupts are not required for this project, V PP (pin 6) is also tied high per the manufacturers specifications. Power considerations The power supply bears some explanation; it provides an op- tional battery-backup system. If you want, you can hard -code the desired entry codes into EPROM. That way you won't need to pro- vide battery backup. But you won't be able to change codes without changing the contents of the EPROM. The 7805 voltage regulator (IC2) maintains the supply at five volts, and filter-capacitor C2 re- moves any noise from the DC supply voltage. A reversed-polar- ity protection diode (D3) is in- cluded to protect against misap- plication of power. Diode D4 serves to "lift" the 7805 's output voltage by about 0. 7 volts to pro- vide an output of 5. 7 volts, which is then dropped by D5 back to 5.0 volts. Diodes D5, D6, andD7 iso- late the battery and the power supply from one another, pre- venting current from flowing from whichever source happens to be active into the other. The batteries supply about 6.0-0.7-0.7 = 4.6 volts. Four AA batteries supply plenty of power to keep the micro- 33K)x3) TO ME68705 Pft3 PA2 R0W1 ROW 2 RA1 RAO ROW 3 ROW* m m lo s m a q m a Fig. 4. AN UNGROUNDED KEYPAD may be used, but you'll have to change the keypad scan routine. An excellent oppor- tunity to get started in 68705 program- ming! controller's memory active (and your entry codes intact), but they can't operate the door latch, so in case of a power failure, you will have to use a key to open the door. If the system encountered a battery failure and a main power failure simultaneously, the mi- crocontroller's memory would be lost. When power was restored, the entry codes would be ini- tialized to the default values stored in EPROM. Diodes D4-D7 may be removed if the battery- backup option is not used. Software design The following describes the software running on the micro- controller; with the information provided, it should be easy to customize operation to your lik- ing. Complete source and object code have been posted on the RE- BBS (516-293-2283, 300/1200 baud, 8N1) in the file DI- GKEY.EXE, a self-extracting compressed file. The compressed file consists of about 20K; run it on a disk with at least 50K of free disk space. FRONT VIEW □ □ Kl NOTE: NOT DRAWN TO SCALE S(£)E y|£W SCREW DOOR JAMB TO MICROCONTROLLER : SCREWS DOOR JAMB 1QO0R FRAME! T 5J4" -H 1 V, " LATCH WHEN 7Cfl HINDGED LATI RELEASES WHEN ENERGIZED MOUNTING HOLES O I Fig. 5. 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Prices subject to change without notice. Shipping Add $3.00 per unit COD S Credit Cards — Add 5% PLEASE PRINT TOTAL G Mastercard FOR OUR RECORDS: DECLARATION OF AUTHORIZED USE — I. it* underaioned. do hereby declare under penalty 01 penury that all products purchased, now and in the future, will only be used on cable TV systems with proper auihonzaikon Irom local officials or cable company officials in accordance with ail applicable federal and state laws. FEDERAL AND VARIOUS STATE LAWS PROVIDE FOR SUBSTANTIAL CRIMINAL AND CIVIL PENALTIES FOR UNAUTHORIZED USE. Dated:. .Signed:. Pacific Cable Company, Inc. 7325% RESEDA BLVD., DEPT. R-3 • RESEDA, CA 91335 (818)716-5914 ■ No Collect Calls • (818)716-5140 IMPORTANT: WHEN CALLING FOR INFORMATION Please have the make and model # ot the equipment used in your area. Thank You > j0 O CO CO o 81 UNICORN YOUR I.C. SOURCE COLLIMATOR PEN A low power collima- tor pen containing a MOVPE grown gain guided GaAIAs laser. This collimator pen de- livers a maximum CW output power of 2.5 mW al25°C. These colli mated laser sources are designed for industrial applications such as data retrieval. telemetry, alignment etc. The non-hermetic stainless steel encapsulation ot the pen is specifically designed for easy alignment in an optical read or write system, and consists of a lens and a laser device. The lens system collimates the diverging laser light. The wavefronl quality is diffraction limited. The housing is circular and precision manufac- tured with a diameter of 1 1.0 mm and an accuracy between + and - 11*im. ■L,I STPn i GC$ 10O .W PRICE $39.99 Quality Components — Low Prices Since tJMW LASER DIODE Designed for general industrial low power ap- plications such as read- ing optical discs, optical memories, bar code scanners, security sys- tems, alignment etc. The gain guided laser is constructed on a n- type gallium arsenide substrate with a Metal Organic Vapor Phase Epitaxial process (MOVPE). The device is mounted in an hermetic S0T148D (diameter 9.0 mm] encapsulation. The SB1053 is standard equipped with a monitor diode, isolated from the case and optically coupled lo the rear emitting facet of the laser. This fast responding monitor diode can be used as a sensor to control the laser optical output level. I itt rnirr ffiafHffi- price $9.99 We Carry A Full Line ot Components CALL FOR FREE CATALOG EPROMS STOCK* FINS DESCRIPTION 114 ffi» 1004- ; JOB ain 06* 4 Ins 1014x8 450ns 1024 x6450ns 2048 x 8 450ns I25v) 20481 8 350ns I25v> 399 379 S79 550 399 3.79 3 19 j 03 TMSITIG 71 1048x8 450ns 629 598 SSB 2IC10 a 2048 x 8 450ns f25v<;M0S) 359 341 3,07 im » 409Bxl4SansaSn 3.79 J to 3.24 2KBV2 n 4096 x 8 200ns t2lv) 379 300 3?4 !J3!t u «mx825toism*} 3.69 351 3,16 «SM H 40Xx8450nsi21t) 3.09 294 265 rusaaz H 4836 X 3450ns 12ft) S79 550 495 ?!CK » 4096 x 8 450ns (2$\t-CM0S) 419 391! 35fl 2164 ?D 21 S1S2 x 8200ns I21v) 399 3/9 3.41 nst a S!92 x 8 250ns <2)v) 359 341 3.07 2TWA-20 3 3192 X 3 200ns (I2.5vi 399 379 ,141 2ISJt a SlS2x 8250ns ()2.Sv) 359 3.41 3.07 THH5W a 3192x3 250ns (25/) 6.79 045 581 m 20.20 a 16.364 x 3 200ns (2lv) i.JU b.W 4.95 27128 a 15,384 x 8 250ns 0V) 4.73 4 55 4.10 Z7CI2I a 16,364 x8 250ns I2W) 539 512 4 01 272S6-20 ■!i 32.766 x 8200ns (12Sr) 5.39 5 09 51? 27250 it 32,758 x 8 250ns (12.5V) 4»- 4 74 4J7 VKX n 32,766x8 250ns (12.5v-OiOSi 599 5.09 512 71512-20 ■a 65,536x8200011125*) 1049 997 097 27512 26 65,536 x 8 250ns (125v) 949 9.02 812. 27CSIE a 65,536x8250(0 (12S DO n x (D SO O 83 10+ UNITS PANASONIC WIRELESS CONVERTER 85.00. . 69.0C JERROLD 400 COMBO W/ REMOTE (DRX3DIC) 134.00. . JERROLD 400 OR 450 REMOTE HAND UNIT 24.00 . JERROLD JRX3DIC B4.00.. JERROLD SB ADD ON 74.00. . JERROLD SB ADD ON WITH TRI-BI 95.00 . . OAK M-3S COMBO 79 00. . OAK MINICODE (N-12) 84.00 HAMLIN MLD 1200 64,00. . SCIENTIFIC ATLANTA SA-3 ADDON 109.00.. INTERFERENCE FILTER (CHANNEL 3 OR 6) 24.00. . NEW SCIENTIFIC ATLANTA COMBO 275.00 . PIONEER DESCR AMBLER 250.00 TOCOM VIP 200.00 . ZENITH FLASHING 175.00 . ZENITH SSAVI 125 00. . EAGLE PD-3 95.00 . VIDEO-LINK Enterprises, Inc. 520 GLENBROOK RD.. SUITE 202 STA MFORD. CT 06906 ORDERS: 1-800-622-9022 CATALOG & INFO: 203-975-7543 MONDAY - FRIDAY 1 AM — 5:30 PM. E.S.T. IMPORTANT: Have make and model # of the equipment used in your area 95.00 15.00 65.00 55.00 70.00 50.00 59.00 45.00 75.00 14.00 215.00 200.00 175.00 150.00 90.00 75.00 QTY ITEM OUTPUT CHANNEL PRICE EACH TOIAL PRICE NO CONNECTICUT SALES. It SUB TOT. is not Ihe intern ol VIDEO-LINK to defraud any pay television Shipping S3 / Unit any company or individual in doing so. PLEASE PRINT: COD: Add 5% TOTAL D CASHIER'S CHECK NAME ADDRESS , CITY/STATE7ZIP PHONE □ M.O. □ C.O.D. O LU O Q < LT 84 SIGNATURE WAIVER, Since i, the undersigned, fulty understand that the ownership of a cable decoder does not give the owner of the decoder the right lo decode or view premium cable channels without proper authorization from their local cable company, hereby declare under penalty of perjury that all products purchased, at any time, will only be used on cable TV systems wilh proper authorization from local officials or cable company officers in accordance with all applicable federal and state taws. Federal and various state taws provide for substantial criminal and civil penalties for unauthorized use. Dated : Signed: AUDIO POWER AMP IC's continued from page 56 CERAMIC OR |C CRYSTAL *Y PICK UP J T cs ± + * 1A 5 ' '-5MEG f 2.7ft Y N FIG. 22—2- OR 5-WATT PHONO AMPLIFIER with RIAA equalization. bridge configuration, to provide 4 watts to an 8-ohm speaker when using a 12-volt power supply. The "bal- ance" potentiometer is used to set the quiescent output of the two IC's at identical values, in order to minimize the quiescent current consumption of the circuit. Note that the LM388 has fairly poor supply-line ripple rejection. If any such problems come about, they can usually be overcome by wiring a 10- p,F (or larger) capacitor between pin 1 and ground. LM380 LM384 circuits The LM380 (Fig. 20) can work with any supply from 8 to 22 volts. It can deliver 2 watts into an 8-ohm load when operated with an 18- volt supply, but it needs a good external heat sink to operate at that power level. Its dif- ferential input terminals are both ground-referenced , and the output au- tomatically sets at a quiescent value of half of the supply voltage. Its volt- age gain is fixed at 50 (34 dB), the output is short-circuit proof, and the IC is provided with internal thermal limiting. The LM384 is simply an "up- rated" version of the LM38Q, capable of operating from up to 28 volts and of delivering 5 watts into an external load. Both IC's are housed in a 14-pin DIP, in which pins 3-5 and 10-12 are intended to be thermally coupled to an external heat sink. Figures 21 and 22 show some prac- tical applications of those two audio- power amplifier IC's. Fig. 21 shows how to use either IC as a simple x 50 amplifier with enhanced ripple rejection (via C2) and a very simple form of volume control (R2). Alter- natively, Fig. 22 shows how to use either IC as a phono amplifier with RIAA equalization (via RI-C4). Also note that either IC can be used in the "bridge" mode to provide extra power when connected the same as Fig, 19. In that setup, a pair of LM380's would produce 4 watts when powered from 18 volts, and a pair of LM384's would produce 10 watts when powered from 22 volts. r-e Husband. Grandfather. Great American Investor. When Bob Lawrence joined the rail- road nearly 30 years ago, he began buying U.S. Savings Bonds for his retirement. Now he buys them for his grandkids. "Bonds pay good strong rates and they're simple to purchase," he says. Become the next Great American Investor. Call us to find out more. US. SAVIHCS BONDS I Fff CiK! *T AMfcROlN iNYlPWtis 1-800-US-BONDS A public ktvim ofthw pubiiuEi&n CIRCLE 64 ON FREE INFORMATION CARD High Performance Universal Counter Tinner Module/Panel Meter FREQUENCY PERIOD RATIO INTEBVftt AVERAGE PRESCALE OVERAtlGE A B SQQQQQQOQO 1 . U . U . O . U . U. O . O . O. Q . 0-01 0.1 ID 111 fOO 100Q LUWBAIT | nX 1 '•: P ,,. . . -,■■.■ • • ■* ■ '. ^ ■ 1 ^'bb-'i^-'^ooti&oot i",l >• •- & ■ " 1 '. B^U ACTUAL SIZE INTRODUCTORY PRICING Quantity MO Tl-99 100 + Price 189.00 159.00 129.00 • lO Digit (120 Segment) LCD Display win :a id input Annun< • I H? to Ovesr BO MH7 Direct Count (1 H? rpsi hot Time interval lOO ns. .1 ns averco • Functions Include: Frequency. Period, Rati me EQUIPMENT PTlIf SHOW YOU WHERE TD Fl BIG UNIQUE. UNUSUAL AND H ARD-TO- FIN D ITEMS ..... .... — Chi YcittJlA »»QO ^ A#iMWktl»i!r*ntBrf*jArt$tS»iQfBKtT«ucfiiif*Htt WANTED INVENTIONS/new products/Ideas wanted: Cal! TLCI for free information 1 (800) 468-7200 24 hours/ day - USA/Canada. INVENTORS! Confused? Need help? Call IMPAC for Free information package. In US and Canada: 1 (BOO) 225-5800. SEISMOMETER wanted to measure earthquakes. Pay cash. D, HUTCHISON, 4000 Little Timber, Ed- mond, OK 73034. (405) 341-9615. 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(603) 673-4730. > X o I !B ■a S 65 CABLE TV DESCRAMBLERS 10 Lot JERROI.D™ Tri-Bi Mode. SI SBJ.00 Ui JERROLD™ SB-3 OR 2 sss.oo S6S.00 u H»mlinMLD-1200 STO.95 S6100 ? Otky-nw/vs S.99.9S 162.00 o Oik-M-35-B W/VJ J99.00 smtx rr OAK E-13....__ S99.9S 158.00 h- ZinilliSSAVt.™. J1S5.00 1145.00 o E»sJ= PD-3 SI20.00 135.00 LU _! 1 1 1 Scientific All una 1129.55 1105.00 SA'Ccmbo't, CALL ICill Tocoiil $350.00 1295.00 D OtkN-UW/Aulo. 1140.00 1105.00 -5 Jermtd Stw«vm CSV.... 1139.95 Cill LU > DC -Z. < °- B -r C < S LU O P CO < 5F5 5 do) 3 w X S < £ *NEW STARGATE 2000 CABLE CO NVERTER 1 -$89.00 10-$69.00 100-Call Last channel recall- Favorite channel select- 75 channel-Channel scan- Manual fine tune- One yearwarranty-surge protection-HRC & Stand- ard swilchable- and much more. Call TfWJav! INFORMATION(402)554-041 7 Orders Call Toll Free 1-800-624-1150 M.D. ELECTRONICS 115 NEW YORK MALL SUITE 133E OMAHA. NE. 68114 BEST BY MAIL Rates: Write National, Bon 5. Sarasota, FL 34130 HAWAIIAN DESIGNS! CATALOG $3.00. "Tiki", Box 3249, Mllllani, HI 96789. FINANCIAL HAVING CREDIT PROBLEMS? For our National Credit Guide rush 127.95 to: DM Manuals, 3377 Wilstilra Blvd., Dept. 1022, Los Angeles, CA 90010. 30 Days Money Back Guarantee! NEED CREDIT? 11.500 + Gold Card. No deposit. No turn- downs. Visa available. 1(602)420-1486. EARN 12,000 PER 1.000 envelopes you process at home. Easy plan. Free Information send self. addressed stamped envelope: Lincoln Enterprises, FOB 752209, Houston, TX 77275-2209. CABLE TV Converters — Desc ram biers Remote Controls— Accessories * Guaranteed Best Prices » * 1 Year Warranty — CO D s » * Immediate Shipping * * FREE CATALOG * CAM or Write TRANS-WORLD GABLE CO. 12062 Southwest 11 7th Court. Suite 126 Miami. Florida 331 86 I 1 -a 00- 44 2 -9333 MASTERCARD AND VISA are now accepted for payment of your advertising. Simply complete the form on trie first page of the Market Center and we will bill. CABLE TV. CONVERTERS WHY PAY A HIGH MONTHLY FEE? All Jerrold, Oak, Hamlin, Zenith, Scientific Atlanta, Magnavox and all specialized cable equipment available for shipment within 24 hours. For fast service MC/ VISA or COD. telephone orders accepted (800) 648-3030 80 Day Guarantee (Quantity Discounts) 8 A.M. to 5 P.M. OS.T. CLOSED WEEK- ENDS. Send sell-addressed Stamped enve- lope (60e postage) for Catalog. GET OUT OF THE DARK. The Consumer Information Catalog will enlighten you with helpful consumer information. It's free by writing — Consumer Information Center Dept. TD, Puebio, Colorado 81009 CIRCLE 53 ON FREE INFORMATION CARD CO g z o o LLI I LU a 86 V70B n-jr, CPU's* CHIPS 7 76 qexcru i. 7i 2KB CPU 3 ? 1 2HA CTC I 3* ZBCM EkWl \ 39 ZKADU* 5 50 Tdo* PiO ■ at wjaud &» if»a sic- a 95 B2C43 3 75 A'-' IX- 30 6502 RAM* 6532 400 334 3.50 1.1ft 4.50 8.03 s so 1.71 1.76 3.75 175 500 aoftii K515450 13.B5 6JW00LI7 19 95 nsm osoo REGISTERS MM 1402 1.76 MM MOO 1 7E MM 1404 l.TE MM5Q13 250 3.50 ug 240 3JK1 INTERFAX A.Y51013A ay; ioim &.W 6.75 3*0 1.76 "r.ivDLii B13 ■314 5215 S3 24 •an 8337-5 Baa asMut 8391 -A S3S3 424* 7.05 8355-A 5 1 (5 *2S7 1.40 8250 2.40 4377A 4.T6 B275 [EDO 8370-5 3 75 8234 2 50 £246 4.71 2.50 ET3L5, '2 35 2 75 TM59027NL.V94 OOOU n w ROM's IW5M5-E AM TPB19S43 3 40 025125 1 50 82ST74 136 BJStM 1 Si 825>30 1.95 &2S131 1 « B2SIS1 4.50 (JSK 1 4 50 745*74 3 05 370* 3 76 3719 *5v J-T9. 2732 3 3 75 3714.25. *M >.71 2713930 *,T5 4.75 27266-35 100 40 3347 34a 4Q J62BA 3 300 nss-a 1 25 IE DO UMCimQA 13 50 DO 7 60 31 L02 3 301 B 31Q1A 4 2111* 31 13-! 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(■; S 40 LM33BK . > 75 340T-5,4,1,13. Si. 25 15.19 fir 34V . . 1 90 73J S2 95 93.75 93 75 t 55 LI41MPI r>wti*. FP 1 OO Photo Trira Ft»nLED-i..3" . , Y* II sw. Cjr**n, at Ambi> Lg LEO'i nti^fir. .-.- :;s :-. 3 ;■ _r.r . IIic-Yki -c-r/il n-a's- L£L^ . . , , MLtt>02 IB LEO WrtDliBPhaia O*", XTOB . . . EL- 5 Of»1o Im>%i:oi d- MCT-J 4 M5 Crno CihJFSl* . .3/91 .00 . ,- t 30 . lOStltOO .8/9100 . . , t .90 . . ,* ,90 . . . 4 .40 £60 TTL SIZE RELAYS 5V DPST 17V 0F5T COPROCESSORS WI7-2 $115.00 8067-3 $ aB.DQ ^OTSJ-t. S1US.0Q jBW-IB 130000 FULL WAVE BRIDGE PRV EA 9A 394 900 110 1 (0 11 DIP SWITCHES CTS304. 4 4 rniiinn TB OTS 206- 7 7Pm,[,an 96 CT5304- 8 I f«.ii)f ,96 CT3 304 10 10 P«.tioi> 1 25 SILICON POWER RECTIFIERS PRV 1A JA 1JA 5DA 134A 740A 100 D6 14 35 3d 900 9 50 3Q0 09 17 50 130 8Q0 11.40 400 09 25 55 1 40 iDOO 13.50 EDO 11 30 BO 2 00 13 00 IB 00 ■00 T3 34 103 2 50 150030 00 1D00 20 45 I 35 300 3000 2400 MULTI TURN TRIM PDTS 60 OHM 100 OHM 1QQ0OMW EC 10K 30K 5QK 1»K _ 3/SZ.QQ POSTAGE RATES ADD 10% FOR ORDERS UNDER 425.00 ADD 5% FOR ORDERS BETWEEN (26,00 AND SlOG.M ADD 3* FOR ORDERS ABOVE StOD.CH TERMS- FQB CAMBRIDGE, MASS SEnO ■Zvl.'ZK dn MONEY OROEH minimum telephone. to.d- puhcwam or deb or charge 520 oo miniwlfm mail oho6b 95 00 SOLID STATE SALES P.O. BOX 740 - SOMERVILLE. MASS. 02143 TEL. (617)547-7053 FAX: (6 17) 492-8845 TOLL FREE 1-800-343-5230 «OH ORDERS ONLY S E MP t 76 FOB OUR CATALQQ FEATUBING TBAH4ISTOFI5 4 n ECTl ■" I E 5 HE 'HAMPSHIRE ST„ CAMBHEOGE, MASE. 071J9 WE SHIP OVER 95% OF OUR ORDERS WITHIN 24 HOURS OF RECEIPT CIRCLE 74 ON FREE INFORMATION CARD AUDIO UPDATE continued from page 77 records. I agreed, and we made a date for the following week. When I arrived, and after Bill in- troduced by to several Japanese engineers, I was ushered into the company listening room. There I was confronted with three visually identical pairs of speakers labeled "A," "B," and "C"— obviously the same model that had been re- viewed so well by our test lab. Bill handed me the control of a three- way switching system and asked me to switch among the three pairs of speakers and evaluate their sound quality. Since all the systems looked identical, I didn't know quite what to expect, but no more than about 15 minutes were needed to arrive at an opinion based on my A/B/C comparisons. I said that according to my ears sys- tem A sounded bad, system B was pretty good, and system C also sounded bad — but different from A. Bill seemed pleased with my re- sponse, but the Japanese seemed puzzled and upset. Here's where the inscrutable part comes in. Later, in private, I asked Bill to explain exactly what was happening. He said that the Japanese had been thrilled by our favorable test report and decided to heavily promote their speaker system in the U.S. In order to save the shipping costs from Japan, they intended to build the systems here, using an American-made cabinet and either local- or Japa- nese-manufactured drivers. To Bill's ears, the two pairs of locally assembled systems (A and C in my tests) sounded quite inferior to the original (B), but the Japanese insisted that they all sounded alike! That's why Bill had brought my ears into the act. I've thought about that experi- ence over the years, and have yet to figure out exactly what went wrong. I can understand that the Japanese engineers might prefer a different sonic quality (frequency balance) than I do, but the fact that they denied that there were any audible differences in the sound of three obviously different- THE ELECTRONIC GOLDMINE iMr'RAilKD UKTKCTOK KIT L'i*i *ti*H(|T* what ±n| t;i«i!ffl*ik do l-u rrx :m mpareJ iin *ll typn t>f i"'r»rrJ TV, VC*. err rfnwir (Miirarkrr inJ 1-tDS by pn^Jiwlrti WLpftel WiJ If hni^ ■ brifhE rid LED Or*« tin ■if*mj: lAtl wi-yfiiriaiihh af irtlnrfi! cUdipMi hi *ktr jrjm CH «« **. Siwll u« IS" * L4 - Opmlfi -on *V bUMF? 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C6AW S 16,95 20 WATT RMS MONO AMP KIT nmui tK»ri et jrpi " j — *jn p«t*«iaii »nij h« Wij- Irnk diuatrian 11% or Irul Amrairwr fin rid IPD "am" liubnuv in J will F'ui~.i inv liint'i fi-Jiu MMItH, CD Ipll^tf K ttHRI C6444 SU r 9S a 6 o rrrrTi^.^. * # 3 ' s i* inciuik qui biiCfcliif L'dfiirriiTtf dwi I l-Pil K.lh r^h niJrr V»m^|li inur yo*i wJfr we *ill p'jff ^mi" MINIMUM ORDlfl S tCflEJl flub J.Ofl ihipin^ mit Jiond-ma W« an.pf W/C, Vhd oid irnn.iT p ir« i CO D ff i: 7.S-D hi a Jifien Ifl 3.00 iU[>jiinii iknrqT. J I |J Q OBPI BS TO; Thr lltnianiL MiWt P.O. Ban S408 SiDllfdalc, fil. 85261 PHONE 0HBIflS:'60?|^t-7-S« CIRCLE 180 ON FREE INFORMATION CARD MARK V HEW fREE CATALOG IS NOW AVAILABLE! CALL (21 3) 888-8988 ORDER TOLL FREE 800-423-3483 IN CALIFORNIA 800-521-MARK FAX (213)888-6868 a indicates the level of difficulty in the assembling of our Products. A Beginner a A Intermediate AAA Advanced * Fully Assembled, lTY-43 ■ NEW&i 7^, TA-120 SM-4l^ TY-23B 9 i ; ^P^ TA-3600 ^* MK2 SM-333 AMPLIFIERS MISCELLANKOl'H MODEL DESCRIPTION KIT TA-28MK2 Digital Voice Racofdar 44 30.00 TA-50A/B Multi-Purpoaa Malody Ganerator A 11.84 TA-SOC MulU-Purooia Molodv Ganarator4 12,65 TA-120MK2 35WCI1I1 "A" Main Powar Mono Arnp.44 27 16 TA-300 30WMuUi-Purpo»eSinotaChannalAmp4 20.00 TA-302 BOW St*reo Powar Boottir 50.00 TA-3221 BOW +50 W IC Sterao Amp. w/Hd Itval display* 35.50 TA-323A 30Wk2 Starao Pra-rnaln Amp. aV 29.50 TA"377A HI-QUALITV FETStarao Pra.Amp.44A,. 5S.95 TA-4O0 40W Solid Slata Mono AmpA 28.00 TA-4T7 120W Moatat Powar Mono Arnp.44 88. 00 TABOO 80W 80WDCPra-Maln.SPow4rAmp.A4 60 92 TA-802 BOW B0WDCSt«raoMalnPow»rAmp.A4 45.94 TA-8J0A 60W SOWOCLDCPia-MalnStaraoAmp 44. 40.39 TA-100OA 10OW □ynamlcClaaa "A" Main Powar Mono Amp. 53.o9 TAI 600 1 0OW 1 2 C [an "A" DC Starao Pra-Mlin Am P4 A 473 . 70 TA.2200 FETSupor class'A "DCPra-Airip 47-70 TA-24O0A ElactronicEchoi Rayalatlon AmpA 44 * S3. 30 TA-2500 HO. Pra-Amo. w/10 band Graphic eoualitar* ... TA-28Q0 BI-FET IC Pra-Amp. w/3 way lona control AA 4B.90 TA-3000 Starao Simulator JFor mono TV of any rrtono iourca]30.20 TA-3SOO 3O0W HO HI-FI Powar Mono Amp. 444 79.00 ASSEMBLED * 16.58 17.71 38.81 28-00 70.00 46.15 38,35 75.00 34.93 49.37 B0.5S 95.81 58.24 116,60 90.80 41.38 1 03.00 MODEL DESCRIPTION " KTf~ TY-23B 3 Channel Color Light Controller 444*. ........ $ 56.04 TY-25 Starao Loud apaakar P rota ctor a 12.68 TY-35 FM Wlreleai MiorophonoA 9.22 TY-36 AC/OCQuartl Digital Clock 4- 16.00 TY-38 SouncVTouch Control SwitchA „. 12,00 TY-41MKH1 Infrared Ramote Control Unit AAA-.... 15.00 TY-41MKV InTrarad Remote Control Unit AAA................. 20.00 TY-42 Bar/Dot Laval Matar A A„................ 24.15 TY.43 3Vi Digital Panel Matar A....... 29.00 TY'45 2 S to p 3 Ba r/ D ot A u d I o Le v a I Di a p I a y 4 A 28-45 TY-47 Superior Eladtronic Roulatta A A 19.46 SM-328 4ChannalProtaalionaECoEorLightControllar.... SM-333 Audio/Video Surround Sound Procaaaor AAA-* 62.00 SM-668 Dynamic Noiae Reduction A 26.00 ASSEMBLED 574.50 18. SS 25,00 35.00 36.00 48.14 27.24 150.00 83.00 34.00 INSTRUMENTS POWER SUPPLIES SM-43 3'A Multl-Functinal Lad D.P.M ,. 34.50 43.00 SM 48 4Vi HlPraclalon O.P.M , 38.00 48.00 SM-46A 4Vi Hi-Precision D.P.M.w.'atndrd cats 41,20 52.00 SM-49 3^ Multl-Functlonal LCD D.P.MIw/hold function) 38.00 44.50 SM-100 150 MC Digital Pre gu an oy Counter 79.00 90.00 FC1000A 1 GHr Frequency Counter ,. 179.00 METAL CABINETS WITH ALUMINUM PANEL: TR-100A 0-1 SV2A Regulated DC Power Supply. S9.S0 89.50 TH-36SA 0-1 5V5AReaulated DC Power Supply 14.55 20.76 TP.-355B O-30V 3A Regulated DC Power Supply 14.55 20.76 TR-503 6-50V3A Regulated DC Power Supply 15.75 22.65 LG-1273 LQ-ieaa LG-1S24 LQ-1025 LG-1SS3 3" CO s 87 CIRCLE 93 ON FREE INFORMATION CARD GHM- ANTIGRWITY GENERATOR SttflO „, LCT- 40 WATT BURNING CUTTING LASER . ..$2(100 J£ * flU B4 - HI POWER PULSED DRILLING LASER $20.00 fpBTCS- 1 MILLION VOLT TESLA COIL . . 520.00 GMCP1- HI VELOCITY COIL GUN S15O0 5LLS1- LASER LIGHT SHOW 3 METHODS , S20IX) CO EH1 - ELECTRONIC H/PNCTISM TECHNIQUES . saOC 3E EM LI - LOWER POWERED COIL GUN LAO NCHER . SMC rfJLS- JACOB LADDER 3 MODELS S1O0O _]SD5- SEEINTHEDARK S10JB Q-LEV1- LEVrTATlON DEVICE J10D0 sJFbWIK -3 MILE FM VOICE TRANSMITTER $3450 5 Ff S1K - HAND CONTROLLED PLASMA FIRE SABER . . $4950 5 HIGTK - HI FLUX NEGATIVE ION GENERATOR . $3450 jySPGSK- PLASMA LIGHTNING GLOBE . . , .$4950 x I LHC2K - VISIBLE SIMULATED 3 COLOR LASER . $4450 £2 H0D1K - HOMING/TRACKING BEEPER TRANSMITTER . . $4450 S S LG U6K - 2 5 MW HAND-HELD VISIBLE LASER GUN $24950 gfEBTC3K-25O.OQOVCiTTABLET0PTESLACOIL $24950 CO I0G2K - ION RAY GUN , protect eneiw wiltiout wires $129 95 f— TKE1K - TELEKINETIC ENHANCER/ELECTRIC MAN $7950 2 VWPH7K- 3 MILE AUTO TELE PHONE TRANSMITTER .$4950 n ASSEMBLED IN OUR LABS ■ ii UST10- INFINITY XMTR Listen in via phone lines $19950 _l IPG70- I NVISIBLE PAIN FIE LD BLAST WMGENEWTORWiO CO IIM10— 1000OOVOLTINTIMIDATDRUPTO20' $9950 £ IM30 - AUTOMATICTELEPHONERECORDINGDEVICE$2450 JJj PSP40 - PHASOR SONIC BLAST WWE PISTOL S8950 CO DNI1 - ALL NEW 26 - VIVID COLORED NEON STICK . $7450 CO LGU2C - 5 TO 1MW VISIBLE RED HeNe LASER GUN $19950' ^ BLS10 - 100,00 WATT BLAST! R DEFENSE WAND . SB950 EASY OHDEHING PHOCEDURE - TOLL FREE 1-800-221-1706 or 24 HRS ON 1-603-673-4730 or FAX IT T0 1-603-672-5406 VISA. MC. CHECK. MO IN USFUNDS. INCLUDE 10% SHIPPING. ORDERS S1 00.00 & UP ONLY ADO $10.00. CATALOG S1 .00 OR FREE WITH ORDER. INFORMATION UNLIMITED P.O. BOX 716. DEFT. HZ, AMHERST, NH 03031 sounding speakers puzzles me to this day. Perhaps something got lost in the translation. Postscript About a year later I had an unex- pected visitor from Japan. The gentleman had been on assign- ment in California for the pre- vious month or so setting up a slow-speed recording center for a major Japanese company. Things had gone well, until the question of monitor speakers for the studio came up. It seems that my visitor felt that the "West- Coast" speakers used by so many U.S. studios suffered from excessive colorations that in his view made it impossible to accu- rately monitor a recording with them. He was in trouble with the home office because he refused to use the "standard" monitors in the studio he had designed. I was surprised and gratified to encounter a Japanese engineer who seem to hear things the same way I did, and we entered into a wide-ranging discussion about sound preference and sonic accuracy. I mentioned that in our test program we had en- countered only one Japanese speaker that tested well and sounded right to our ears. "Yes," said my new friend, "1 know of your test report since I designed that speaker, and, incidentally, it was a best seller in Japan!" I was flabbergasted ! There should be a lesson tn all this— other than that some people, whatever their na- tionality, can hear and others can't — but I'll be damned if I know what it is. R-E w o ■z. O DC H O LU _l LU 6 Q < ir 88 I E Parts EMINENCE J^r ® 1-800-338-0531 -^ motorola Potydax 0»!)n»ioi\ieen 3-WAY 100W CROSSOVER ISdB/cctave roUoff. 800Hz, 5000Hz ■crossover points. 8 ohm, 100 waits RMS, m #260-210 $12.50 (1-9) $9.95 (10-up) SPEAKER CONTROL PANEL Final with 50 wan L-pi for tweeter and midrangs *nd built-in LED power meter, 5"a 2 V2~ 100 watt vcnion available $14.50 #200-235 (1-5) $12.90 (6-up) 12 POLY WOOFER Super duty, 40 «. magnet, 100 welts SMS, US welts max, 4 and B ohm compat- ible (6 ohm), r voice coiL Ss=2SHz.QTS = .16t, VtS^ 10.8 cu(t. Response: 23-1500 Hi. tiei weight: lbs. Pioneer #A30GU*0-S1D #290-125 *?£|° $34.50 (4-up) WALNUT SPEAKER CABINET KIT,. Super quality, genuine walnut veneer cabinet- Kit includes: routed and mitred top, iidei r and bottom in unfinished 3/4" walnut veneer. Cut your own custom holes in the front and rear to match your drivers, IS* i 24* k 11". Volume: 1.3 cubic fee', #260*350 522.50 $19.95 (1-3) (4-up) PIONEER HORN TWEETER Mylar dome. 3-93 oi- barium fenite magnet. 8 ohm. Response: 1800- 20000 Hi 35V/ RMS. SOW max fc-aOOGBi, SPL 106 d». Pioneer #AHE60-51F * ■? 2 10-050 w g.r $5.90 (10-up) -Parts 'express 340 E. First 5-.. Dayton, Oho 49402 local: ! -513-222-01 73 FAX S13-H2-4&U " i5d*ymor*y bade euawitM "SlSflOnmiTuinoedaf 'Waionpt Matuittari, Via, Diacow, and COD, onion r %t hem =Jiep4.tj "Shipping Chugs- UPS chart rim * $1JX) ($3.00 minimum cfiinjel 'Kauri: 330 *m- 6:QG pm EST. MoticUy - Friday "Mid ordar cunom*ri. pl*u* can for ihippLng «tim*r.t on OTdftTS tXCMding 5 Dm. 12" SUB WOOFER Dual voice coil sub woofer. 30 oz. magnet, 2 voice coils. 100 watts RMS, 143 watts max. Is - 39 Hs. 6 ohm (4 and 3 ohm compatible). SPI,=89dB 1W/1M. Response: 23-700 Hi. OTS = .31, VM= 10.3 cu.fi.. Pioneer » A30CU30-55O. Net weight 6 lbs. #290-145 f$f° $36.80 (4-up) 15" THRUSTER WOOFER Thruster by Eminence. Made in USA. Poly foam surround, 56 or. mao^net. 2-1/2T, 2 layer voice coil. 130 watts RMS. 210 watts max. 4 ohm. Is = Z3.B Bs.OTS = .33, VAS^IT.9 cuft.SPL=9,.BdB 1W/ 1M- Net weight: IS lbs. ,..-. ,~. S43.50 #290-180 18" EMINENCE WOOFER MADE IN USA 100 oi. magnel, 3" voice coil. 290 wans RMS, 350 wans mil. S ohm. 30 Hs resonant frequency. 22- 2100 Hi response. Efficiency: 93 dB 1W/1M. Paper cone, treated accordian surround. Net weight: 29 lbs. #290-200 $98,90 (1-3) $89.50 (4-up) TITiiNIUM COMPOSITE TWEETER . • dona EoconvbxvtChB advmtigBKof M r A Mchndogwn 0ohm Fww Quad coobd mot cod, Lt=120QHx. sfl :-: ■■■■13 /■•■' :*■'. go mm iems. ^ i 70 wittt ibm- 4' rotmd- Polyd« E*il*DTWlCOT^ . ¥22aS0 $24.80 #210-047 (1-9) (10-up) GRILL FRAME KIT With this lot you cut make speaker grill fraxneiup to 30" i 40". Kit includes 4 comer pieces. 2 T" brackets, and 7 frame bars. Grdl mounting kit included, #260-333 CIRCLE 56 ON FREE INFORMATION CARD 4>6some to help America . prepare for I theiuture. Support America's colleges. Because college is more than a place where young people are preparing for their future. It's where America — and American business — is preparing for its future. Give to the college of your choice. DESCRAMBLERS "The Empire Strikes Back" *r*. 'We Cut Prices To The Bare Essentials" There Is NO Competition ANYWHERE ! JERROLD™ TB-3 SCIENTIFIC ATLANTA SA-3 HAMUN MLD1200 OAK M35B W/VAR1-SYNC [NTELESTAR I CONVERTERS DF-3/2 RLTERS FULL 10%UNDERANYONES Quoted or Advertised Prices For Ordering & Info Please Call Even The m ^? ie (Gigs! (402)331 -3228 SALES REGULATED BY FEDERAL & STATE LAW ANYONE IMPLYING THEFT OF SERVICES WILL BE DENIED PURCHASE C»bli Hrtw>;k fr . ..■:■!]> % [Ogth 5l SB W ' S ■ .N. NE MI37 mttkM ***** if** K* "*mHBH*. 13 O I to CO o 89 Mill Ord*r EtKlnxiies ■ World#»i*# l ameco lEESEIIZIEl Mail-Order 24- Hour Order Hotline w o z g _l UJ 6 o SIP & SIMM MODULES Pin Ho. Function 5!2Kl'T- IBMPS2 10*B256KI9SlMM(2iacni 2MEGKIT IBWP52 lOWBlMEG<9SIMM(!tllii) 41256A9A10 262,144*9 102-4 255*. .9 SIP [His leads! (1256A9B80 282.14(19 60ns 256K > 9 5iMV 421000ASB1G 1.045576*6 103W lV£G*6S!yM . 421000A9ABO 1.046.579*9 90ns 1MEG*9SIP IKISLtaosi 421000A9S60 '.046.576*9 60ns 1M£Gi3 SiW 'Upgnda to* Models 30. 50Z and SO P'lM 119 95 (6995 (J 55 !!S .194% 16995 19999 7400 .1-9 I IN- 7402 7404.- 7405..., 7406... 7407..., 740B.. 7410 7411 7414 7416. 7417,. 7420 , 7427 _ 7430, 7432 __ 74^8 7442 7445^ . 7*46 7447 7473 __ 23 .19 29 19 29 .19 35 -25 39 23 39 29 .35 .25 29 .19 35 -28 ,49 39 55 .25 25 .25 .29 .18 .29 .19 -29 .19 39 .29 39 .29 .15 39 .75 .65 .89 .79 m .73 39 .25 Part Ho. 7474 7475. 7476.,..-.- 74S3 7485 7485... 74S9... 7490 7493. 7495 74107. ._ 74121 74123 74125. 74147 74150 74151 74161 i. 74174— 74175. 74193... . 39 IS - .45 . 53 - .85 . .45 . 2 25 . 49 . .45 - .59 . .29 , 39 , .49 . .49 . 1,99 - 135 ,. 39 . 135 .. .69 ,. .59 - .69' . .79 _U2± .29 39 35 49 55 35 2.15 39 .35 .49 125 29 ■ ■!':. .59 49 .49 74LS 74LS00. 741502... 74LS03 741S04 74LS05 741306 74LS07_ 74LS08. 74LS09 74LS10 74LSU.._- 74LS14. 74LS20 74LS21 74LS27 74LS30 74LS32. 74LS38 74L542. 74L547— ..- 74LS73 74L574 74LS75 74LS76 744.583- .28 2S 28 .28 59 ,58 .28 .28 .26 28 ,49 39 .28 IS m .19 .35 25 28 18 21 .16 35 26 .49 39 55 .39 74LSS5... 35 25 39 -29 .39 29 .56 .45 74LS86- 74LS90... 74LS93... 74LS123 74LS125- 74LS132... 74L5138... 23 49 .49 ,49 .49 49 74LS139. 74LS151 . 74LS153 74LS154.... 74LS157 .. 74LS151... 74LS163 74LSIS4... 74LS165... 74LSI66. 74LS173 74LS174... 74LS175. 74LS19I- 74L5192 ... 74LS193... 74LS194.... 74LS221 .. 74LS240. 74LS241-. 74L5244 74LS24S 74L5257 74LS259 .. 74LS273 74LS279... 74LS367. 741S373 74LS374 74LS393 74LS54I 74U5S90 M.Si: - .49 39 .49 39 .49 .39 1:29 1,19 .45 35 49 39 .49 39 59 .49 .75 .65 .89 .79 .45 35 39 29 39 29 59 .49 .69 .59 .69 .59 69 .59 69 .59 59 .49 .59 .49 59 .49 .79 .69 .49 39 .99 .89 59 .79 .49 39 49 39 .79 .69 .79 59 .89 .79 1.291.19 5.95 5.55 233 229 74S/PROMS* 74SO0 .25 74S1 86" -.„.__ 1.49 74S04 _ 25 74SIB9 1.49 74S32 -25 7432(0. 139 74S74 „ 25 74S244 .99 74S113 25 74S2S7'.- 1.49 74S124 156 74S26S- „_„ 1.49 745373 S3 33 745163 .75 715387* 123 74S174 23 74S472 - 2i 919219 9192>I SI 32. a 9192x1 Si SI.! 102414 3276SiS 33.799(0 32.76ti9 32.796(9 2i.7S8(8 I20na... ■5:-: 2M^SlCh,t 262.144(1 -4I-I4 (5.53614 95.536i4 «5536i4 292.14411 1.041576(1 1.049.576(1 262.144(4 2(2.144(4 120m. 150ns . _. l&Qr_iMM5293»<2.!.. 150ns (PfjjYOackl,,, , 100ns 120ns , 150ns . 60ns- 90ns- 595 -549 -1.18 4.49 -275 -239 100ns... taw... 15flj_... laiaWUnHAM..... K-5 , 120-1 , . 150m 100ns Sialic COflimi!. Bona 11 Magi.. .. lKnsMMegl lDOnsfl Majni 1 00ns SUbc Column. ...215 -595 — 5.75 .3.95 ,-3.69 „.3.25 .10.95 ,-5.95 ...4.49 . ..4.25 195 ...1395 ...1295 .. 14.49 .2695 EPROMS 7MS2516 TMS2532 -MS2S54 Tl»S27i6 1702A I":. 2719 27161 27CK 2732 27321.-20 27C32 2764-25 27644 2-D 2764A2S 27C94-15 27121-20 27121-25 2712IA-SS 27126A-20 27C-128-25 ;-;f! ■■: 27259-20 27256 25 2JC256 IE 27C256-25 27512-25 _-.:■; IS 27C5-2 2S 27C0W 15 BI714 99769-35 20(619 4099(1 409619 9192i9 2048il 256i6 1024il 204!il 204M 204(11 4096(1 4096(6 4096(6 1192(6 6192(9 6192(8 6192(9 iSJ*m 15.38418 iE.: id s 16.31411 16.3(411 32.766.6 32.766.1 32.766-6 ?i ■-{.• a76M (5536(8 (5.539(9 65 536(8 131.072(6 1192(9 1192(8 |25Y].., 450m li. 4K«_!!25sn. 150ns 12517) 450«l5V..5«.-t2U|- 2K|1|U1 . 450ns 450ns (25VI .495 -59S 350 _ ;ZSVt 450ns !2SV| CMOS 450ns I25»S KWnsl?1V) ..5.25 ,.6.95 .-6.19 (25 ..995 -3(9 ..3.95 (25 -3 95 450ns 125V) CMOS _ 250ns [21V: 2t0nsfl2 5V| 2K»_(125VJ - __ 150W12JV)CM0S 20WS(ZW| 2501- 2 IVU 150ns (12.5V1 200nsd25VI . 2SOns!21V|CMOS 150ns 112 5Vi 200ns 112 5V; 2S0nsll25V) .395 -419 .349 ...4.9S S.9S 695 .175 5 95 >50ns 112 5V( CI/OS 250ns 1 12SVi CMOS 750r_|125V|- 150ns 112 IV, CMOS 9.(9 ,4_S 250ns 1125V) CMOS lS0nll2.SViCVC.li Vagi t4X(W-{2SV] On-0Sni3tj . 64* 3KHS rJSVr lOliW EnaWi 725 5(9 7.25 995 749 1995 1495 1S9S EEPROMS 2616A-25 2049iS 250ns |9V'5V| 5V RMdWHH . .5.49 2817A 204BXB 350ns 5V Head.'Wrlta ...6.96 2894 A Sl92x8250ns5V Head 'Wrlla [pin 1 rfej n a ' 0.95 28S5A fl192»8250n3 5VHea0iWII» 10.95 8000 SERIES Continued anna. Ban B2S6 229 8741 _ 9.49 B742 14.95 8748 (25V[ 7.95 8748mHMQSK2llfl ... 9.95 8749- 996 8751 H [3 5 12MHzl ...34.95 8756 1395 80286-10 11 0MHSLCC 29 95 80267-3 1 5MHz[ 10995 80287-8 (SHHz) 209.95 80287-10 (10U Hi).. ,239.95 80386-16 PGA 259.95 80387-16 [16MHz) .349.95 80387-20 (20UHz). .399.95 80387.25 [25MHz:,..., 499.96 82284 18MHz) 5.49 822BB(8MHz) 655 DATA ACQUISITION ADC0804LCN 3.25 AD0O80BCCN 5.49 ADCOeOKXDN 3.75, ADC1205CCJ-1 19.95 OACO0O8LCN 1.49 AV-3-1015O 4,95 AV-5.1013A -...2.95 .S500/6800 68000 Series P an Ho . 6402.. 6602 . 6502A... 65C02(CMOS) ... 6620 6522 65022 6532. 6551 55C802 (CMOSI .. 6800 6802 6808 __.. 6810 6820 6821 68821 6840 6845 6850 — 6852 MC68O00I5 MC6eooono...... MC68O08P8 MC68010L10 MC68020 BC 128 MC684SOL10 . _ MC6870I MC68705P3S MC66705U33 MC66B91RC16A MC68681 HC20A PUM .3.75 .2-19 .259 .5.95 .159 .2.95 ....425 ....495 .. .269 .15.95 ...175 2.95 2.49 12S 2.75 1.75 225 3.49 ...2.75 ...1 75 75 .. .995 -.1155 _.8.49 .1995 .. 59 95 .2955 ...1955 .16.96 .17.95 .129.95 .159.95 Commodore WD1770 8.95 6504A... . 1 19 6510- 14.95 6526 13.95 652SA 14.95 654S-1 3.95 6560 . 6.95 6567. 24 95 8672 655 6681 (12V) 1295 8502 7.95 8564 296 6566. ... 695 9.9S 6722 8.95 •S25100PLA".. 1595 325672-01 17.95 901225-01 1595 901226-01 - 1595 901227-02. 4.85 901227-03 .1555 901229-05 1595 90! 460 -03. 1.95 901486-06 2.9S MISC. COMPONENTS 'No specs available "Ntj-tB 3JS100P\A - U 17 lC*4J 74C/CMOS 735V ,69 POTENTIOMETERS Values available [insBfl onms Into space martiod "XX - [. 500(1, 1K, 2K, 5K. 10K. 20K. 50K. 1 0OK, 200K. 1MES 43PXX 3J Wait is turn .99 !&3PXXi2W[in ilurr. .89 TRANSISTORS AND DIODES PN2222 . .13 PN2907... ., 13 1N4004... , 10 ;Ni2£2..\ . 29 2N440I...- .15 1N4148... . ._ .07 2N3D55 fiO, 1N270 , JS IN4735 . 25 2N3904 . 12 1N751 .....15 C106B1 ... .49 SWITCHES JMT123 SPOT Qn-On 1,25 I 206-6 BPST. 16.pw0IP MPCI21 SPOT.OM5K1. 1.26 MS102SPS1. 1 -9 39 D-SUB CONNECTORS DB25P Mafe.25.pin ,69 I D825S F»male, 25-pin XC209B 11. (toll XC556RT1", HM LEDS I XC556G ri". Groan .161 J3L IC SOCKETS low Prolite SLP 1 1 ULP 12 16LP 13 24LP -21 28LP 23 40LP 29 witeWraptGoia)L 8WW 14WW 16WW ___..._ 24WW 28WW 40WW 1 19 1.39 {G&o 4 7m] 4 himh Pkvg S«Nb> 4fH 4ntlpt4> 74HC HI-SPEED CMOS PnriNS. 74HO00 74HC02 74HC04 74HC08 74HC10.. 74HC14 74HC30 74HC32 74HC74 74HC75 74HC76 74HCS5- 74HC86 74HC123 74HC125, 74HC132 74HC138— .. 74HC139 74MC164-. 74HC163 74HC174 _pflia .. .19 ... .19 -. .19 19 19 23 ..-.2S 25 29 56 25 55 29 59 43 . . 49 45 39 1 49 ... 39 .-.. .59 P"1W" 74HC175 ... 74HC221 .... 74HC240 .... 74HC244 .... 74H0245-... 74HC253.... 74H02S9.,.. 74HC273.... 74HC373.... 74HC374.... 74HC596,,.. 74HC688.... 74HC943.... 74HC-4O40. 74HC4049 74HC4050 .. 74HC4060. 74HC4511.. 74HC4514.. 74HC4S38.. 74MC4543 Ettci .... 59 — .69 69 79 79 49 49 .49 ... 59 ... £9 ...129 ...1.49 . -6.95 .79 ....99 . 1.79 .1.19 . 1.19 74HCT-CMOS TTL 74HCT0O 74HCTD2 _..17 74HCT04 19 74HCT08 -17 74HCT1(.,._ 29 74HCT32 19 74HCT74 29 74HOT86 25 74HCT136 „.. ^9 74HOT139 74HGT1S7 . 74HCT174 74HCT175 . 74HCT240 74HCT244 . 74HCT245 74HCT373 . 74HCT374 .. LINEAR Part No. -^L TL071CP „ 59 TL072CP .79 U074CN 99 T1081CP „ 59 TL0S2OP S3 TL0B4CN .99 LM307N 45 LM308N 65 LM309K 1.49 LM310N 1.49 LM311N 49 LM317T ,61 LM318N 1.09 LM319N —129 LM323K 3.49 LM324N 39 LM3352 1.49 LM33S2 1.09 LW337T 129 LM336K 4.49 LM339N .49 L.F347N 1.49 LM346N .69 LF351N 49 LF353M 59 LF356N B9 LF357N 99 LM358N 59 LM380N. 89 LM38521.2 1.75 LM386N-3 ,.,. .89 LM393N 45 LF398N 1J5 LFj'ir^, 7:1 LF412CN 129 N6555V 35 XF11555- 75 LM556H 49 LM565N... 59 LM566CN 129 LM567V .75 LM723CN 49 LM741CN 35 LM747CN 59 LM1458N 39 LM1488N 49 _Lfl.-_ 59 59 as .49 si. ■5 59 1.26 ■ 25 34 59 .99 I ''I 3.25 .35 125 33 1 09 J 1 Multimeter w/Frsquency 4 Capacitance , $69.95 3650B SameasM3650w.'BarBrsph.„.$79.95 4650 4.5 Dial ^Frequency, Capacitance and Data hold Smich $99.95 PROTOTYPING PRODUCTS Jameco Solderless Breadboards I IBM Compatible j Ea , 12 Cases and Power Supplies JEI0I0 JE1011 JE1018 JE1D30 JEtttJS JE2011 JE2D12 JE2Q14 JEi-019 Flp-TojSancamiPCJXICae- $3955 stsisatara foxier. ssass Srt easy AT Cms .,„.„„„„.„...» $59.95 150 oaf PCXT Pome $4dr •■ $59.95 K0 «* °jej AT Paw Sjioiy S89.S5 v«iCH,w3rjC(w Pw Supy $OT°5 tUn-Venc* Cue w230W Pv. Supy-- $1 4955 nc-Tte Ees, XT Tuba Cut $6855 tyi w Bity Aica» $6955 EGA & Multiscan Monitor Packages Casper 14" EGA monitor and EGA card package (720 x 350 max, resolution) JE1 059 EGA Monitor i. EGA Card $459.95 Relisys 14" Multiscan monitor and EGA card package (800 x 600 max. resolution) JE2057 Multiscan Monitor & EGA Card $559.95 IBM PC/XT/AT Compatible Keyboards II 1 1 1 Efl^hea QB JE2017 JE2015 tM-Koy Standard AT Slyte Layout ..$59.95 JE1016 101- Key Enhanced Layout with iz Function Key $69.95 JE2016 ill-Key Enhanced Willi Solar Powered Calculator ..$79.95 JE2017 i C4-Key Enhanced witn TrackbaU I Microsoft Compatible) ....$99.95 — " A.R.T. EPROM Programmer ■ Programs all current EPROMs in the 2716 to 27512 range plus the X2864 | EEPROM • RS232 port • Software incl. EPP $179.95 UVP EPROM Eraser r • Erases all EPROM's • Erases 1 chip in 15 Mln. and 8 chips in 21 min. • UV intensity: 6800 UW/CM* DE4 $69.95 . '.„ ' 3.5" and 5.25' Floppy Disk Drives MPFll Pictured Sony MPF1 1 3 .$- 720K6 Inismal Omra .... $69.95 SMK 5.25' Installation Ki w/Faceplate ..$14.95 Toshiba 355 KU 3.5" 1.<4Mb Internal Pnve $109.95 TE4C FD55B 5.25-3eoKonaiiHi. $99.95 FD55G 5.15-UMbHaiiHL $119.95 Jameco J E 1 020 5 .15' 380KB H»t HI. BlacK $89.95 JE1021 SJ>5-JBQKbHa;tHl Gray $89.95 JE1022 SJ6- 1 2MB Halt Hi Gray $99.95 Soldering and Desoldering Stations 60 Watt Analog Display Soldering Station * Electronic temperature control from 200° to 878°F - Cartridge heating element for a longer life of Itie soldering tip XY1683 $59.95 60 Watt Analog Display Soldering Station • Electronic temperature control Irom 200° to 878° F * Ceramic heating element tor a steady temperature and long life XY2660 $89.95 60 Watt Digital Display Soldering Station • Electronic temperature control from 200° to 878° F ■ Temperature displayed on easy to read ,560"H 3-digrt LED readout • Nichrome heating element XY960 $99.95 30 Watt Electronic Temperature Controlled Desoldering Station • Electronic temperature control from 212 J to 842"F • Self- contained high rotary vacuum pump XY999 $279.95 Hard & Hard/Floppy Disk Controller Cards MJM ttird/Floppy KLLKndfflaCT Computar Type Mt |TOaT) fr l:1lnlenaa¥i IBM JATV3M 8 ?;1 Infrrtwi leaatMWMSinuinoim Ptrt No. I Price Perl No. Price KWAJ7X5S9 85 ■::;■. '.".!■ tmx mavSRUmss tOMVmitlUig | 1035 VSR 1 -SI 63 « Part No. ( Price txivwmjsitjH iam*it1i»«s Pin No. ; Price 355 Shoreway Road lelmont, CA 94002 •4 Hour Order Hotline (415) 592-8097 'AX'S (415) 592-2503 or (415) 595-2664 'elex 176043 - Ans. Back: Jameco Blmt )ata Sheets - 50c each land $2.00 Postage /or a FREE 80-Peg* Catalog I 1990 Jameco Electronics 3/90 3M is a registered trademark ol nernalional Business Machines VISA' Mm! Ordur ELKtrtmiCi ■ Worldw id* ameco ELECTRONICS IVUVIC $25.00 Minimum Order - U.S. Funds Only L CA Residents Add 6%, 6.5% ot 7% Sales Tax I Shipping - Add 5% plus $1.50 Insurance | (May vary according to weighi and shipping method) Terms: Pciras subject tc change TVithoul notice. [ We are not r&spon-sibrs for typographical e-rora, We reserve lha right to substitute munutaeturers. Items suoject O X CD HWi»4!»M W tlWQtUu CIRCLE 82 ON FREE INFORMATION CARD • QUALITY PARTS •DISCOUNT PRICES •FAST SHIPPING M.L ELECTROniCS CORP. ha VOLT DC MINI FAN I Howard Industries* I 3-1 5- BIO. Operates on ] 12 Vdc, 0.10 amp. 1.0 wait | Compact pEaaac housing, 235" tquaraX 1.27S - WcV." I 9 blade fan. Two 9* pigtail leads. |cAT#CF-121 59 00 each 115 VAC COOLING FAN STANDARD SIZE COOL HG FAN. I Features die cast metal nouaing I for strength and durability. IMPEDANCE PROTECTED * 11/16"aquar»X1 1 1T Amp. Factory new 120 Vac fans, CF1-N $9.50 each LED CHASER KIT -ft* ^x Build this variable speed led chaser. 10 teds flash sequeftt&Hy at whatever speed you set tti&m for, Easy to build kit includes pc board, parts and instructions. Ideal for special lighting effects, costumes. etc. Operates on 3 to 9 volts. PCboardis 5" X 2.25". A great one hour project. CATfAEC $6.50 each | TIL-9& PHOTO TRANSISTOR TO- IB cajo win wlndcw. For wlea-angta viewing ■pplrcaElona. SpBdralry inj msdian icaHv conpa:- ble whh TIL-31B. C*IiTtL-» 1 Sl.OOsach * 10 lor $0.00 " ^ TIL-31B PHOTO DIODE . TO-1& c*s*wtrh window. Irfrwd tmttilna photo diode, till TlLaie (loom. - !0!«Js.5O SWITCHES ITT PUSH BUTTON nTMDPL series. 3M"X .■rgs'S I 1/2" grey rectangular ^nT^f keycap.S.P.S.T,N.O. I Push locfrae. RATED: 0.1 amp switching. | 0.25 amp carry current. P.O. mount CATfPB-a 655 each- IOIorK.00 100lorJS0.u0 ISPDT PUSHBUTTON Marquarda 18« I Rated 6 amps @ 125T250 Vac. Black plastic push butler. I Switch botfy:.92"X.M"X.6S-, lcATIPB-19 (1 65 ea. • 10 lot $1.50 each PUSHBUTTON SWITCH I GC/Thomsen* 35-420 Q I S.P.S.T. normally open momentary ^=3) I pushbutton switch. Red plastic TKT I actuator 0.57" diameter. Chrome rj I bezel 068" diameter. Threaded I bushing mounts in .50" diarnoior hole. Rated I 3 amp @ 250Vac. Solder loop terminals. |cAT*PB-20 $1.00 each I MINIATURE TOGGLE SWITCH a S.P.D.T.(Of+ON) 1 I Rated: 5 amp @ SLi 120 Vac. Solder H9 I lug terrr- rials, fjfJ CATtUTS-4 J1 .35 each 10for*12.50 - 100 k» (110.00 ALL PLUG CfflECTLY HTO 120 VAC OUTLET t?Vfc@50o ma. " CATs DCTJ-iss 14.50 6 Vec Q 200 ma. CAT« DCTX-aso S2.2S 9 Voi ® 1 amp CAT* DCXT-M1 SS.OO 34 Vac & B2S ma, 0ATI ACTX-246S 13,25 NICKEL-CAD BATTERIES (RECHARGE A RLE) AAA SIZE 51.50 mcti '..J von* 160 mAh CAT* NCB-AAA AA SIZE 12.00 ok h 1,25 VQftt 500 mAh CATi WCB-AA AA SIZE 12.20 *Kh WITH SOLDER TABS CAT* WCB-3AA G5IZE U25*aiti 1.2 vota 1200 mAh CATff NCS-C DSI2E t*.50oikcfi 1.2- Will 1200iflAI. CAT* NCB-D STEPPER MOTOR Airpax* A82743-M4 Brand new 1 2 volt dc stepper motor. 35 ohm coil. 7.5 degrees per step. 2.25" diameter, 0.93" long excluding shaft. 0.22" dia. shaft is 0,75" long. 2 hob mounting flange, 2.675' mounting centers. 6 wire leads. CAT#SMT-5 $10.00 each XENON TUBE r long llatMubs with 3 1/2" red Bird bladi ludi. .do.i 1or etfldronlc Hash or lirotfl projoclE. I CAT* PLT-S 2 for $1.00 RELAYS ^ 5-C VDC SIP REED RELAY EJoOrOl ■tii-.o&oy* aus'AQ&Aie S-6 Vcfc, 500 ohm pqILS.P-ST. normaly open rood relay. 0.& amp oanUBti, s&p wnikjura- Ikm. T X .37S" X ,5*. CATt HHLV-5IPS f.'Smh * lO'cllS.OO 5 VDC LATCHING RELAY Aroma]* RSL20-SV Minlatura- SPOT, ■:bai cci ialchfl; raiay.SVdft 170 ohm cod*. 1 imp. TTL com- palblo, UL and GSA racggnljod 0.787" X 0.334" X 0.39** CATi LRLY-&DC 52.50 MCh 12 VOLT DC. COIL S.P.D.T, Omronf G2E-184P 4 imp contact*. 335 ohm qq 53 0-30 MINUTE AUTO- SHUTOFF TIMER Sankyo Seihe Mlg.»TMCF35MYB3 120 Vac 60 hz. 10 amp contacts. UL rated. Turn shaft lo torn on lights or other electrical devices. Betl rings and circuit breaks after specified amount of lime. Ideal tor any device Stat needs to shut off automatically. 2.92" X 1.9" X 254" behind lace plate. 1/4" halt-round shaft. CAT* TMC-30 $3.00 each PHOTO FLASH CAPACITOR Rubyconi FKX 200 mid. 330 volts. 0.79" diameter X 1.11" high Solder bop terminajs. CAT# PPC-200 $3.25 each 1 for $30.00 • 100 (or $275.00 22/44 PiN CONNECTOR 'mil llliiitr 1 .156" pin spacing. 0.200" between double rows, gold contacts, P.C. mounting. SPECIAL. Same as AMP# 2-530655-6. I CAT* EBC-1G $1.00 each • 10 for $o.00 I ELECTRONIC GAME BOARD Tho Innor wofWngi of tn o^ctrcnic ScTnbttto g*mo. Op- •fdot on & Voc. a digit •btwnufrwio rudoui. 45 but- con tUyfiod. 14 LrinKtilon. £ I.C.'i, 1 pazo flletnonl uhji ahof ooodi«. Top *nd bottom row ol keypad bultonf wo lundlon Koyt, mickjl* 3 row* v« aphatwlc No ln- lirueibflS fiVUitUG. 6* X 4.45*. CAT*ST^ |1,75MCh 10 fw $15.00 TELEPHONE COUP UN Q TRANSFORMER MuHl PwIuchi hmomitkinAlf A1SN-HOILV1 Prirrhvy: 60Q oftm atcondvy; eOOv&OO ohm 0,7rX0.6rX0^3*hl8h r e p.c. pint on 0.187" csnron. Primiry Inductance: 300 mH ™ p> « lkRi, i vol. CATiTCTX-1 $1.25 uch * 10 tor #11.00 RECHARGEABLE BATTERY PACK (USED)I Four AA nickel cadmium batteries connected in series to make a 4.8 volt pack. Batteries ate in a 2X2 configuraton with a 2 pin connector attached. The four batteries can be separated into single AA size solder tab nickel cadmium batteries or rssoloered into other configurations. SPECIAL SALE PRICE NOW $3.00 per pack • 10 packs for $25.00 CAT# NCB-41AAU LED'S STANDARD JUMBO DIFFUSED T1-3/4SLU ftRGD CAT* LED-1 10tOY$1.5Q »10QrorS13.00 GftEEH CAT* LED-2 ltJfwttjW-T»tort17.M YELLOW CAT* LED-1 Hlte( 12.00 MOOfwJIT.OO FLASHING LED . with buKt in tlathkvj drcui jt\\ AEG 11.00 HPh I CAT* LED-4 ■-SiorM.Sof GfJEEH tl.OOoSCti I CAT* LE.CMG 10 rOr £D.&c' B1-P0LAR LEDf L^rti RED on* 5i'&"cn, I GREEN BM othor. Two leadi T CAT* LED-6 2 'or i i.70 LED HOLDER -=» T>w tKogo hoW«. O ' CATi HLE0 10 tor 66t ^ 10 AMP SOLID STATE flELAY ELECTnCHJ 52178 CONTROL R«ot)&.5to10Vdc CiW-ll oporaio on 3-32 Vd'c] . LOAD: 10 it (^ 240 Vk 4VrX 13T4"X7^a'. OAT* SSRLY-108 S3 M OL QUANTITY DISCOUNT 10 lOf IE 5. 30 * 25 fff 1 17S.D0 50 lor J30Q.OO - 100 tor SSOO.Du OPTO SENSOR U «iuvod pack&f« Wllh rrounEimj earn. 1<6" opor-ng. 3t4* rnountlnjM/i. CAT* OSU-6 SOCiKh" itjfof H.aj • iro tor 540.00 AX. LINE CORDS Blacken.. 1tV?.SPT-2 NON POLARIZED PLUG CAT* LCAC 2 tor 11 .00 1D0 lor 545.00 POLARIZED PLUG CAT* LCP-1 60c d.uKft IOOIrjrSiO.00 LaE.D. FLASHEH KIT Two L.E.D. 1 * ito»h m ^1/; I unhoninilMnalivDfi I birtsry hs tttachod. Thh ki inekjdM i ^ JJ I p.C. r»*rr3. Ill In* t*3^^ I ptrtt and iraiructioni to miko a tlrr^ tlu^or tr- | cut A quick and oaty c^jjeoi tor anyono wMh baik;| t til*. CATt LEDKIT »1 .75 por kk LOOK WHAT $1.00 WILL BUY /4a*, I 200 ASSOHTED /*a»| 1M WATT RESISTORS I Otnt l«ids, ciffron comp. xnd cirtjan lilm. CAT! GHES Si .CO per ainrtnwit 200 ASSOHTED /^Qk U2 WATT HESlSTOflS rCIO-1 Sent lend, caroon comp. and film. OAT# GHADRE $1.00 par usenmenl 9 H 50 ASSORTED DISC CAPACETOHS MoeC juo cul (p.e. HafiiJ). Sorr* To 500 volts. CATt GRA9DC $1.00 per auonrMtit 15 VALUES OF M ELECTROLYTICS 1^ Conlalnt both axial and radial t[>-|fl5 Irom 1 nrld. =™? CAT* GRABCP $1.00 par tHOHm*nt LOOK WHAT $2.00 WILL BUY 15 AMP SNAP ACTION SWITCH Spaces d i I5afr*p t2& r 250 Vac normoiliF- opon t'*-ich Body ifl i a*- x 54»- x mt. Button txttnov 3.-16" nibovt iwitdi body. CAT* GHABMS JJ.OO par pnekago TO-92 TRANSISTORS - I 20 4M«flBdTO-92plailiCCa*6 a | I trw.jljto™. Vartoutt?y-M of ht I MPl. and PNP. Soma homa I mjyiod, com tiindird rrtarklnQ. | CAT* GRTRN £2.00 por auorlmant SWITCHES I 10 assorted alkfa, I 1&JD 1 *- rotary,, puthemton I and r Dckor ■ vrtxhao, I I CAT* GRABSW 12,00 per ma CALL OR WRITE FOR OUR awn Mao, mm mm 60 PAGE CATALOG OVER 4000 PARTS! fiutnartomtsconn. i ^-_1'»0t>-B;t.i<3? H " J-"-J.U B -'.p ;,- :s '' iE B .'.-zii_ -■- ' km OUTSIDE THE U.S.A. SEND $2.00 POSTAGE FOR A CATALOGII ORDER TOLL FREE 1-800-826-5432 MAIL ORDERS TO: ALL ELECTRONICS P.O. BOX 567 VAN NUYS, CA 91408 INFO: (818)904-0524 FAX: {818)781-2653 MINIMUM ORDER $10.00 QUANTITIES LIMITED CALIF. ADD SALES TAX USA: $3.50 SHIPPING FOREIGN ORDERS INCLUDE SUFFICIENT SHIPPING. NO C.O.D. > o DC (0 to o CIRCLE t07 ON FREE INFORMATION CARD 93 tv J I ii DYNAMIC RAMS PART* 4154-150 4164-120 HH-rM TMS4464-15 7MS446-M2 TMS4464-10 41258-150 41156-120 41258-100 41256-80 41256-60 4t4255-100 414256-80 1 MB-120 1 MB-100 1 MB-80 65536i1 65536x1 65536x1 65536x4 65536x4 65536x4 262144x1 262144x1 262144X1 262144x1 262144x1 263144x4 262144x4 1048576x1 1048576X1 1048576x1 SPEED 150ns 120ns 100ns 150ns 120ns 100ns 150ns 120ns 100ns 80ns eons 100ns 80ns 120ns 100ns 60ns SIMM/SIP MODULES PART* 41256A9B-12 41256A9B-80 421000 A8B-10 421OOQA9B-10 421000A9B-80 256KX9SIF-80 256XX9SIP-60 1MBX9SIP-8D PARTi HM6116LP-2 HM6264LP-1S HM6264LP-12 HM43255LP-1? HM43256LP-10 SIZE 256k X 9 256Kx9 lMBxS 1MB ■ 9 1MBx9 256KX9 256KX9 1MB I 9 SPEED 120(15 80ns 100ns 100ns 80ns 50ns 80ns TYPE SIMM/PC SIMMrPC SIMMfMAC SIMMrPC SIMJWPC StP.'PC StPrPC SIPJPC 36.35 49.95 109.95 113.95 119 95 54.95 64.95 124.95 STATIC RAMS SIZE 2046x9 8192x8 8192x8 32766x8 32768x8 SPEED 120ns '.50ns 120ns 120ns 100ns MATH COPROCESSORS 8-BIT COPROCESSORS 8087 5 MH; 89.95 8087-2 S MH: 129.95 S0E7-1 "1 MH: 169.95 Jf 6-BIT COPROCESSORS 80287 6 MH: 139.95 80287-8 8 MH: 209.95 B0287-1D lOMHl 239.95 B0C287 IZMHi 299.95 32-BIT COPROCESSORS 80387-16 IB MH: 350.95 S03B7-SX 16 MHz 319.95 80387-20 20 MH: 399.95 80387-25 25 MHz 499.95 80387-33 33MHz 649.95 5 YEAR WARRANTY INCLUDES MANUAL 1 SOFTWARE GUIDE 74 SERIES LOGIC 7400 74LS00 74LS02 740* 74LSW 74S04 7406 7408 74LS03 7432 74LS32 74LS73 7474 74LS74 74S74 r.lLSliB 74LS15S 74LS163 74LS24Q 74LS244 74LS245 74LS273 749233 74LS322 74L5367 T4LS373 74LS374 T4LS393 7JLS6S2 74LS6SB C.PM. '* 8000 B052AH BASIC 34.95 5088 S.99 8250 6.95 8251 A 1.69 8253-5 1.95 8254 9.95 8255-5 2.49 8741 9.95 8748 7.95 8749 9.95 8755 14.95 6500 6SC02' 7.95 6522 2.95 V-20 V20 6.95 V20-8 8.95 V2O-10 11.95 V30 13.95 MISC DAC0800 3.29 1793 9.95 COM8116 8.95 MCI 468 18 5.95 MM58167 9.95 IN58250 6.95 NS16450 10.95 LM317T .69 NE555 .29 LM741 .29 7W5T .49 7812T .49 75150 1.95 75154 1.95 14411 9.95 CRYSTAL OSCILLATORS 1.0MHI 5.95 1.5432 5.95 20.0 4.95 24.Q 4.95 PALS 1GL3 2.S 16R4 2.S 1 6H6 2.9 16P.8 2.1 20L6 4.95 20RSA 4.95 20H6 4.95 2008 4.95 20X8 4.95 PAL KIT AN ENTRY-LEVEL | COMPLETE PAL DEVELOPMENT KIT FROM CUPL. FULL SUPPORT FOR 16L8.16R4. 16R6. 16RB.20L8. 2QR4, 20R6. 20R8. AND 20X8. MOD-MPL-SOFT 199.95 De fid's HIGH-TECH SPOTLIGHT FTU'1-U MiBin im.n.m.ii,.Mi.iui.ii.nuiii.i l uii!n Memory tpeed rntingi «sm lo cause good oeoi of contusion, probably because many people are unsure of I lie maximum rolings 01 Inoir equipment When you buy rasrer memory than your CPU requires, you vrBI not process data any rosier than If you bough! irirr slower memory, but many people do spend the ox Ira 5-10% and buy rosier memory anyway, for some, the reason Is "margin tor error", and others. Uke myself are looking Info the Mure at Ihe next generation of CPU's will no doubl require faster memory. This list of Intel based processors contains Inforrmatlon thai should determine whloli memory speed you require. It is not exhaustive, and may differ trom the specifications which come with your Computet. Please use Itle manufacturers recommen- dation! when In doubl. CPU Speed Standard wall 1 wart Interleaved SMtu 150ns - 6088 8065 60286 60285 6028* 80284 60286 lOMhl tt.lh: JMruj lOMhz l2Mtu !6Mhz 120ns 80265 20Mlli 80364 IrSMhl 80366 20Mtu 80386 25MM Deficit Moore. Director of Engineering MOtli 200ni - IMni 200ni - ICOm 150ni - Mru 120nt •r 60 nt IDJfiL l2Dfi* <50n> 60n. 40ni 60ns lOCni 120ns < 50ns BOm IGOni cttm BOiH SOns EPROMS PART# 2716-1 2732A 2764 2764-250 2754-200 27C64 27125 2712SA-200 27256 27256-200 27C256 27512 27CS12 27C101-20 SIZE 2048i8 4096x8 8192i3 8192x8 6192x8 8192x6 16384«B 16384x8 32768x8 32768x8 32768x6 65536x8 65536x8 131072x8 SPEED 3S0ru 250ns 450ns 250ns SOOrts 250ns 200ns 250ns 200ns 250ns 250ns 250ns 200ns Vpp 25V 21V 12.SV 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V 12.5V PUIS PRICE 24 3.95 Model Timer- fal Cnip$ Intensity | Unit 1 (uW.'Cmlj COM PE-140 ' NO PE-140T : YES PE-240T YES PL-265T ' YES 9 12 30 8,000 1 1 89.95 8,000 1139.95 9,6«0 *1 89.95 9,600 1 1255.95 EPROM ERASERS DATARASEIt $ 39.95 • SHIRT POCKET SIZE! ' 'J^>£>^ • ALL SIZES UP TO i AT A TIME " « ^4.2A. 5V@ 5A. .12Vr|l.5A PS-135 S59.S-S PS-150 150W SUPPLY S69.95 PS-200X 200W SUPPLY W9.95 200 WATT ■ ATCOMPAT1SLE - UL APPROVED • 1 10-220V SWITCH - ^5V@20A. *12Vl9 7A. «^ -SV@5A,-12V@iA tW- PS>200 .SB9.95 PS-250 250W SUPPLY S129.95 tVI icrocouput e R MARKETING CGuNCll & tr* Dna i: PROTOTYPE CARDS ffl-4 EPOXy GLASS LAMINATE WfTH SOLD PLATED EDGECARD FINGERS AND SILK SCREENED LEGENDS FOR XT JDR-PR1 WITH *5V AND GROUND PLANE 27.95 JDR-PR2 ABOVE WITH IrO DECODING LAYOUT ... 29.95 JDR-PR2-PK PARTS KIT FOR JORPR2 ABOVE 8.95 FOR AT JDR-PR10 BIT WITH IrO DECODING LAYOUT 34.95 JDR-PR10-PK PARTS KIT FOR JDRPR10 ABOVE 12.95 FOR PS/3 JDH-PH32 32 BIT PROTOTYPE CARD „.-.S9J5 JDR-PR16 16 BIT WITH TO DECODING LAYOUT 49.95 JDH-PH16-PK PARTS KIT FOHJDR- PR 16 ABOVE 15.95 JDR-PH16V 16 BIT FOR VIDEO APPLICATIONS 39.95 EXTENDER CARDS SIMPLIFY PRO TOTYPIHG AND TESTING EXT-8086 8 BIT FOR 8088 MOTHERBOARDS 29.95 EXT -80286 1 6-BIT FOR 2867386 MOTH E RBOARDS .39.95 EXT-16 MICROCHANNEL 16-BFT 69.95 EXT-32 MICROCHANNEL 32-BIT 99.95 PC BRBADBOARD-ON-A-CARD • 62 BUSLINES ■ USE UPTOZ4 14-P1NICS ■ 1940 TIE POINTS ■ DB25 D-SUB CONNECT PDS-604 $49.95 FQm SOLDER STATION • UL APPROVED . ADJUSTABLE HEAT SETTING ■ TIP TEMPERATURE READOUT ■ REPLACEMENT TIPS @ (2.95 16S-3C S59.95 IC SOCKETS/DIP CONNECTORS SOLDERTAIL 6 PIN ST .11 14 PEN ST ,11 16 PIN ST .12 18 PIN ST .15 20 PIN ST .18 24 PIN ST ,20 28 PIN ST .22 40 PIN ST JO MALE DB09P DB15P NDB15P DB19P EB25P DB37P . DB50P H/lffEkV/MP 8 PIN WW .59 14 PIN WW .69 16 PIN WW .69 18 PIN WW .99 20 PIN WW 1.09 24 PIN WW 1.49 28 PIN WW 1.69 40 PIN WW 1.99 7UP D-S1/W1 FEMALE DB09S .49 DB15S .69 HDB15S 1.59 DS19S .75 DB25S .75 DB37S 1.39 DUOS 2.29 J ZIF SOCKETS ZIF-14 5.95 ZIF-16 5.95 ZIF-20 6.95 ZIF-24 7.95 ZIF-28 7.95 ZIF-40 10.95 IDC'S IDE20 IDE34 IDS20 IDS34 IDB09P IDS09S IDB25P IDB25S CABLES AND GENDER CHANGERS MOLDED; HOLD-PLATED CONTACTS; 100% SHIELDED CBL-PRNTER 6 FT. PC PRINTEH CABLE 9.95 CBL-PRNTR-25 25 FT, PC PRINTER CABLE 15.95 CBL-PRtfTR-RA RIGHT ANGLE PRINTER CABLE 15.95 CBL-DB25-MM OB25MALE-DB25 MALE 6 FT 9.95 CBL-OB25-MF OB25 MALE-DB25 FEMALE 6 FT 9.95 CBL-9-SERIAL DB9 FEMALE-DB2S MALE 6 FT 6.95 CBL-KBD -EXT 5 FT. KEYBOARD EXTENSION 7,95 CBL-CNT-MM 36-PIN CENTRONICS -MAI 14.95 CBL-FDC-EXT 37-PIN EXT. FLOPPY CABLE 955 CBL-MNT-9 9-PtN MONITOH EXTENSION tUS CSL-MNT-1 5 15-PIN MONITOR EXTENSION CABLE 9.95 C B L- MODEM MODEM DB25DB25FEMALE 6.95 GENDER-VGA DB9-DB1 5 ADAPTOR _ 4.95 GENDER-9-25 DB9DB25 SERIAL ADAPTOR 4.95 PARTIAL LISTINGS ONLY— CALL FOR FREE 100-PG CATALOG! COPYRIGHT 1983 JBR MirnOQE VICES jDR MICH00EVICES AND THE JDfl MIC RODE VICES LOGO ARE REGISTERED TRADEMARKS OF J0R MICR00C tflCES IBM, AT. PS/2 ARE TRADEMARKS OF INTERNATIONAL BUSINESS MACHINES CIRCLE 113 ON FREE INFORMATION CARD DEALERS CIRCLE 170 ON FREE INFORMATION CARD 4800/2400 BAUD FAX/DATA MODEM^ $119** ■ FAX TRANSMISSION ONLY ■ 4800 BAUD FAX CAPABILITY TO ANY GROUP III FAX ■ 2400 BAUD V.22BIX DATA MODEM] ■ XT/AT COMPATIBLE HALF CARE ' MENU-DRIVEN SOFTWARE ■ MULTIPLE FAX TRANSMISSIONS TO GROUPED ADDRESSES MCT-FAXM 2400 BAUD MODEM $89 9S ■ 2400/12001300 BAUD ■ FULL HAYES COMPATIBILITY • CONFIGURE AS COM 1, COM2, COM3 OR COM 4 • BUILT-IN SPEAKEH ■ AUTO WAIT-FOfl-DIAL TONE AND AUTO-REDIAL* PROCOMM COMMUNICATIONS SOFTWARE ■ MADE IN THE USA MCT-241 MCT-121 1200 BAUD INTERNAL MODEM $59.95 MINI UPRIGHT CASE $ 199 $ SMALL FOOTPRINT MINI-UPRIGHT FOR 8086 OR MINI 266*356 MOTHERBOARDS ■ ROOM FOR 6 EXPANSION CARDS ■ HOLDS 3 5- 1 /4 a 1 3- 1/2 OR IVES (1/2 HT) ■ 200 WATT POWER SUPPLY • 2-D1GIT LEO SPEED DISPLAY • 12"HXie - LXa - W CASE-120 UPRIGHT CASE $ 249 95 SPACE SAVING DESIGN HOLDS ALL SIZES OF MOTHERBOARDS AND INCLUDES: • 25. LOGITECH MICE m> •• • THREE-BUTTON SERIES 9 %jt " Iflf'ttllu * 320 DPI RESOLUTION Luuri lu n . serial ps/2 compatible \P~ LOGC9 SERIAL MOUSE ._... $98.95 LOGC9-C SERIAL (NOT PSffl COMPATIBLE) $79.95 LOGC9-P SERIALMOUSEWITH PAINTSHOW „. $1 09.95 LOGC9-PC SERIAL MOUSE WITH PAINT/CAD $154.95 LOGB9 bus mouse $69.95 LOGB9-P BUS MOUSE WITH PAINTSHOW $104.95 LOGB9-PC BUS MOUSE WITH PAINT/CAD $149.95 JDR MICRODEVICES 2233 BRANHAM LANE. SAN JOSE 95124 LOCAL (408) 559-1200 FAX (408) 559-0?50 TELEX 171-110 RETAIL STORE: 1256 S. BASC0NI AVE.. SAN JOSE. CA (408) 947-8881 HOURS: Wl-F 9-7 SAT. 9-5 SUN. 12-4 Tdfiyiv MiiimruTn rjrder S>0 flO. Fu> "Hiippmg & hiintilmg inctude S3 50 IfH ground a $4 SO l9p mieIIduI hoIicp '■'> .m? rpspoiisittlc f ai lypograpriiccil cuom. Wc iescrvr. b the nyrn lo nmii quartliKcsand \o ORDER TOLL FREE 800-538-5000 CUSTOMER SERVICE TOLL-FREE 800-538-5001 • TECHNICAL SUPPORT TOLL-FREE 800 538-5002 CIRCLE 113 ON FREE INFORMATION CARD DEALERS CIRCLE 170 ON FREE INFORMATION CARD VALUE-PRICED TEST EQUIPMENT ALL WITH A 2 YEAR WARRANTY! ■mi 35 MHZ DUAL TRACE $A0095 oscilloscope *rSrSf - WIDE BANDWIDTH • VARIABLE HOLDOFF MOOEL-3500 (SHOWN) W MHZ DUAL TRACE OSCILLOSCOPE '389.95 ■ TV SYNC FILTER • COMPONENTS TESTEFI MODEL 2000 195 1MB THE ULTIMATE $ 7Q< 3.5 DIGIT DIMM f*7~ ■ BASIC DC ACCURACY JOSS* ■ 3* RANGES ■ TEMP, TRANSISTOR S RESISTANCE FEATURES DMM-300 (SHOWN! 3.5 DIGIT FULL FUNCTION DMM '49.95 ■ BASIC DC ACCURACY ±0.25* • MftANSES D MM- 2 00 $49.95 3.S DIGIT POCKET SIZE DMM '29.98 • BASIC DC ACCURACY ±0.5% • 14 RANGES DMM-1Q0 S.S DiOft PROBE TYPE VMM ■ AUTOHANGING ■ AOOC2V-500V, • RESISTANCE: 2K-2M DPM-1000 (SHOWN) HIGH, LOW LOGIC PROBE '17.95 ■ DETECTS TTL/CMOS LOGIC STATES • MEMORY FUNCTON FREEZES DATA FOR LATER USE LP-2800 PfJLSEM PROBE FOR QUICK DEBUGGING '19.95 | • INJECTS PULSE INTO TEST CIRCUIT-VARIABLE WIDTH ■ TTL. OTL. TRL. HTL. HI NIL, MOS. A CMOS COMPATIBLE LP-540 $ 54 95 JIM'S BARGAIN HUNTERS CORNER JfW'j VP Salts DFI 400 DPI $17ff>i HANDY SCANNER 3000+ •QUICKLY SCANS IMAGES UP TO 4.1" WIDE • 100. 200, 300 « 400 DPI IN BOTH DIRECTIONS 'G1W AND 3 HALF-TONE MOOES •32 LEVELS OF GRAY SCALE •HERCULES, CGA. EGA AND VGA COMPATIBLE •INCLUDES INTERFACE CARD •INCLUDES PC PAINTBRUSH SOFTWARE TO PAINT. ROTATE. FLIP. SHRINK. EXPAND, TILIT, INVERT AND ADO TEXT TO YOUR IMAGES •IMAGE EDITOR UTILITY PERMrTS 00* ROTATION AND ABILITY TO SAVE IN WINDOWS. GEM, HALO AND PC PAINTBRUSH FORMATS •IMAGE TOOLS TO ALLOW MERGING OF GRAPHICS WrTH OTHER APPLICATIONS HS-3000 WAS SI 99.95 EXPIRES 3/1 5/90 aCJDR Microdevices ■■ 2233 BRANHAM LANE SAN JOSE. CA 95124 ORDER TOLL-FREE 800-538-5000 LOCAL MOB I 559-1200 CUSTODIER SERVICE BDO-53B-5001 TECH SUPPORT BOO-538-5002 FAX (408) 559-0250 CIRCLE 113 ON FREE INFORMATION CARD 96 DEALERS CIRCLE 170 ON FREE INFORMATION CARD ADVERTISING INDEX RADIO-ELECTRONICS does not assume any responsibility for errors that may appear in the index below. Free Information Number Page 108 75 107 84 67 109 70 200 50 192 55 58 187 127 82 ISO 121 193 86 AMC Sales 20 Ace Products 30 All Electronics 93 Amazing Concepts 85 Appliance Service 30 Banner Technical Books 24 C&SSales 15 CEI , 80 CIE 29, 19 Cable Network 89 Caig Laboratories 24 Chcnesko Products 30 Command Productions 61 Contact East 30 Cook's Institute 66 D&D Electronics 67 Damark International CV3 Deco Industries 30 Digi-Key 92 Electronic Goldmine 87 Electronics Book Club 62 Electronic Tech. Today 69 Fluke Manufacturing CV2 Global Specialties 5 Grantham College 41 Healhkit ,21 188,189 ICS 20.69 — Information Unlimited 88 181 International Components Corp .89 113,170 JDR Microdevices 94, 95, 96 114 Jameco , 90-91 115 Jensen Tools 30 182 Jinco Computers 83 — King Wholesale 80 LEARN 13 MCM Electronics 83 MD Electronics 86 Mark V, Electronics 87 McGraw Hill Book Club 44 Microprocessors Unltd. 78 Mouser 66 Movie Time 16 NESDA 26 87 53 93 61 117 199 — NR1 Schools 3. II 190,191 Optoelectronics 12, 85 — Pacific Cable SI 56 Parts Express 88 — People's College or Indep. Study . 25 78 Radio Shack 7 197, 198 SCO Electronics 69 183 Sequoia Publishing. 30 176, 177 Sencore CV4, 23 74 Solid State Sales 86 — Star Circuits 26 195 TECI 70 194 Tentel 61 186 Unicorn 82 198 U.S. Cable TV 69 64 Video-Link 84 184 Viejo Publications 67 185 WPT Publications 70 Gern shack Publications, Inc. 500-B Bi-County Blvd. Farmingdale. NY 11735 1(516) 293-3000 President: Larry Stockier Vice President: Cathy Steckler For Advertising ONLY 516-293-3000 Fax 1 516-293-3115 Larry Steckler publisher Arline Fish man advertising director Denise Haven advertising assistant Christina Estrada advertising associate Lisa Strassman credit manager SALES OFFICES EAST/SOUTHEAST Stanley Levitan Eastern Sales Manager FJadt o-E lectron tcs 259-23 57th Avenue Little Neck, NY 11362 1-718-428-6037, 1-516-293-3000 Ml DWEST/Texas/ Arkansas/ Okla. Ralph Bergen Midwest Sales Manager Rad io- El ectro n ics 540 Frontage Road— Suite 339 Northfield, IL 60093 1-312-446-1444 Fax 1-312-446-8451 PACIFIC COAST/ Mountain States Marvin Green Pacific Sales Manager Radio- Electroni cs 5430 Van Nuys Blvd. Suite 316 VanNuys, CA91401 1-818-986-2001 Fax 1-818-936-2009 ORDER TODAY!! WMMABK 1-800-729-9000 INTERNATIONAL, THE "GREA T DEAL " CATALOG PACKARD BELL = ^jvh America grew up fi^tcninf" ttt ut- It milt tttiQS. V— i PACKMATE 286 COMPUTER^ 3.,„ W7 VGA COLOR MONITOR ■ B0286 micro- processor (operates al 12MHZJ. • One 3-1/2" 1 .44 MB lloppy drive. •One 5-1. <4" 1.22 MB lloppy drive. • 30 MB hard drive. • t MB RAM on motherboard expandable to 3 MB. ■ Includes VGA 14" color moniEor and VGA card. ■ IBM compatible. • AT compatible. ■ 8 expansion slots. ■ Dual FDDIHDD controller. • 2 half height drive cavities exposed. • 1 half height drive cavity enclosed. ■ 2 serial ports. - 1 parallel port. -101 key keyboard. ■ System configuration in CMOS with battery back-up. • Includes MS DOS 3.3 and GW BASIC. • 1 45W Universal power supply. ' Zero wail slate. • Socket for 80287 co-processor on motherboard. • One Year Warranty! • Factory New & Perfect! Mfg. Sugg. Retail: $3,449.00 *1499 Item No. 13-1793-132142 Insured Ship/Hand,: 539.00 f£MITH TURBOSPORT386 PORTABLE LAPTOP COMPUTER 80386 32-bit processor. 12/6MHi(siMtchabte]. 40 MB (28ms) hard drive. One 3.5" 1.4 MB floppy disk drive. -2 MB RAM. 100% IBM compatible. ■Page- White" fluorescent backlil LCD display. 10.5" viewing area. MS-DOS 3.21 included. Supports: MS OS/2 version 1.0, Xenix, and Microsott Windows/38S environments. Zero wait stale. Socket lor 80387 numeric coprocessor. Internal Hayes 2400 Baud modem. Serial and parallel printer ports. Resolution: 640 x 400 pixels. 79-key Full function detachable keyboard- Real time clock and calendar. ■Fast" charge NiCad battery Mfg. Sugg. Retail pack included. AC adapter. Dim.:13.25"Wx14,75"Dx 4.75"H. Weight: 14.7 lbs. One Year Warranty! Factory New I Factory Perfect! 5T A oMB S £ Ha" 1 . > $8,499.00 ■■U.'.H:l!JJ:lUJ $2999 Hem No. B-t 793-1 28686 Insured Ship/Hand.: $19.00 moxon micro-size CORDLESS RADAR DETECTOR • Instant-on radar gun "pulse" signals and alerts you in 1/10 of a second! ■ Detects X and K band radar ■ Micro-size., .only 4-1/2"Wx3-1M"Di 11/16*H. ■ InstaLokft dual conversion superheterodyne receiver. ■ SmarTrac* ami Falsing alarm circuit blocks raise signals. * Different audio warnings for X and K band ■ LED signal strength indicators. * CHy/highway switch. ■ Audio jack. ■ Uses six "AA" batteries fnol included) • Wt: 6-1/20*. ■ Model RD-XL « 00 Day Warranty! Accessories Include: ■ Earphone, spring visor clip, suclion cup windshield mount, corddips H hookS foop fasteners. straight & coded power cords with p4ugs, battery case, and soil vinyl Carrying case. Mfg. Sugg, Retail: $249.95 Emaaaaaa Item No. B- 1793- 132761 Insured StiipfHand.; $5.00 STAR STAND ALONE CORDLESS PHONE BIACK&OECKER Introducing a modern-de- signed tele- phone for today-with long range reception. Now you can pick-up this phone at an UNHEARD OF LOW PRICE! ■ Stand alone design. * Auto redial. - Frequency; 46-49 MHz * Call button from base to phone. * Tone/pulse dialing. * Includes rechargeable nickel cadmium batteries. ■ Contemporary styling. * High quality electronics. * Model* CP-40. ■ 90 Day Warranty! ■ Factory Newt t Factory Perfect! Mfg. Sugg. Retail: $199.00 ■■MlMsMAIhlJ *59 Item No. B-1 793-1 29049 nsured Ship/Hand.: $5.00 DELUXE WIRELESS intelligent home SECURITY SYSTEM security system, ^_ Detects intruder | during entry. 1 Wireless for easy installation. * Oilficull to defeat because of new. advanced technology. ■ Lamp command flashes lamp upon intrusion. ■ Signal relay — relays entry sensor intrusion signal from a remote area of your home to controller. ■ Tamper resistant. * 85 decibel alarm on inside siren. ■ Piercing 1 20 decibel outside- siren, ■ Fail-safe battery back-up. * Low battery warning. ■ 2 Year Warranty! ■ Factory New & Perfect! Mfg Sugg. Retail: $698,00 Includes: * 3 entry sensors. 1 system controller (includes inside siren). 1 signal relay, i lamp command. 1 outside siren, 2 window stickers, 1 yard sign, and complete Item No. B-i 793-1 33389 hardware and batteries. Insured Ship/Hand.: S14.00 HALOGEN TORCHIERE FLOOR LAMP Fill your room with light from this sleek-looking Halogen Torchiere Floor Lamp. It's truly a lamp of the '90s with its stylish modern design and up- ward position shade. ■ Halogen torchiere floor lamp. • Shines light upward, yet fills entire room. ■ Variable light control switch. ■500 Watt halogen bulb included. ■ Sleek, black finish. • U.L approved. ■ Contemporary design. ■ Glass insert below shade allows light to shine downward also — for a complete lighting effect. $299 • Height: Approx • 1 Year Warranty! • Factory New! Factory Perfect! 72'. Mfg. Sugg. Retail: St 70.00 $ 59 Hem No. B- 1793-1 279 11 Insured Ship/Hand.: S9.C FOR FASTEST SERVICE CALL TOLL FREE 1-800-729-9000 CUSTOMER SERVICE: 1-612-56S.4940 NAME . ADDRESS. CITY PHONE ST- ZIP. %m D Check/Money Order □ VISA SIGNATURE. □ MasterCard □ Discover CARD NO OTY DESCRIPTION ITEM* SJHrt PRICE DELIVERY TO 41 U S CONTINENTAL STATES ONLY SUB TOTAL In MN add 6% Sales Tax Total Sim GRAND TOTAL B-1793 EXP. DATE, Send To: DAMARK INTERNATIONAL, INC., 6707 Shingle Creek Parkway, Minneapolis, MN 55430 Introducing The SG80 AM Stereo- FM Stereo Analyzer ™ Now For The First Time, A High-Performance AM Stereo (C-QUAM) - FM Stereo Analyzer Integrated Into One Unit, Allowing You To Performance Test, Troubleshoot, And Align To Manufacturers' Requirements BF .|FN1FXSISN*1- AM STEREO- F>» STEREO ftNW.«Eft \ : ^l H ids: Sf.lFOUT?BTLe«L fwMvew|E „ : »uu»v. |U1l v ~ — H I #»«* S B «1»* SF -if««°T uT ,f,if?sn Jf J 1*0 fBW iFi* WW Patented Licensed Under Motorola Patent No. 4,218,586 Complete AM Stereo-FM Stereo Analyzer— exceeds manufacturers' requirements. Patented FM analyzing signals isolate any FM receiver defect. Exclusive integrated AM Stereo C-QUAM analyzer. Digitally accurate performance tests meet EIA/IHF requirements. Exclusive, tuneable FM-IF Sweep and Markers— aligns all IF stages. Expandable FM features for future service needs, plus SCA compatible. Twice the capability for less than 1/2 the cost of stand-alone instruments. C-QUAM ered trademark ol Motoro 3200 Sencora Drive. Sioux Falls, South Dakota 5 -w Ask About A t0 Day Video Preview }^3$