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1. X 76 MODERN ELECTRONICS November 1990 Say You Saw It In Modern Electronics WWW americanradiohistorv com Infrared Thermometer from page 31 FIELD OF VIEW About 6 Thermopile detector About 1 Fig 7 For accurate temperature mea surement object must fill field of view of sensor in probe The smaller the object the closer the probe must be held to it Potentiometer R4 is provided for setting circuit gain Decreasing its re sistance increases the gain of the cir cuit and thus increases the ther mometer s sensitivity As an alter nate adjust R4 and R76 so the meter indicates the correct hand and inside wall temperatures Several adjust ments will likely be necessary to get calibration to be near perfect Assuming you have performed preliminary calibration of the adap ter fill a small plastic bucket to about one quarter full with small ice cubes and add enough cold water to fill the bucket to the half way mark Keeping the end ofthe probe about two inches from the water take the temperature of the water It should register between 32 and 34 F If not adjust R176 so it does Caution Do not point the probe at an ice cube Its temperature may be much lower than freezing For optimum accur acy use the ice water and an inside wall as temperature stan
2. strange world that lies between fact and fiction Rm pr RPG Ue ur em mu Lindsay s Electrical Books l Box 583 WE6 Manteno IL 60950 I Enclosed is 1 00 Send me a copy of Lindsay s i i Electrical Books catalog via first class maill i Name 2 0 o i Address l City St Zip Lm ee eee 23 Project An Infrared Thermometer Accessory Lets any DMM measure temperatures fast without requiring physical contact Thomas R Fox n infrared thermometer can do seemingly amazing things measure the temperature of acloud layer from the ground and with a special rig the surface temper ature of the moon and Mars More mundane uses include temperature measurement of moving objects and non contact measurements of haz ardous objects like high voltage and radioactive equipment The response of an IR thermometer is also fast An infrared thermometer is also useful in applications in which con tact thermometers are traditionally used For example it can be used for making quick checks of building in sulation and weather stripping for estimating heating cooling loss Too a non contact infrared ther mometer that accurately measures temperature in the 85 to 115 F range has obvious utility in medicine Good as it is though the infrared ther mometer cannot fully replace the mercury thermometer whose advan tages include greater accuracy and lower cost But for specialized non co
3. 1897P 14 95 3145 519 95 BASIC 1532P 14 95 nics cura For over 25 years your most complete a A i source for electronics books FHE ENCYCLOPEDIA OF ELECTRONIC Membership Benefits Big Savings In addition to this introductory IRCUITS offer you keep saving substantially with members prices of up to 50 off the C 2707 26 95 3195P 21 95 publishers prices Bonus Books Starting immediately you will be eligible for RUDOLF F GRAF Counts as 2 Countea our Bonus Book Plan with savings of up to 80 off publishers prices Club m i mum News Bulletins 15 times per year you will receive the Book Clut News describ V guy uy ur num nm OHONANZA ing all the current selactions mains alternates extras plus bonus offers and DI wes a special sales with sccres of titles to choose from Automatic Order If you want Tag yn aw m ects ROBOT rRos the Main Selection dc nothing and it will be sent to you automatically If you prefer ual ee a i another selectian or no book at all simply indicate your choice cn the reply form Yi uy Ju f provided You will have at least 10 days to decide As a member you agree to p P9 E M uw How to Test purchase at least 3 books within the next 12 months and may resign at any time f pr hene thereafter e Ironclad No Risk Guarantee If not satisfied with your books return P p p P a 21 5 them within 10 days without obligatio
4. featured in the Aug ust 1990 issue of Modern Electronics In the same issue appeared the Darkroom Exposure Meter for which would like to know the equivalent for the Vactec VT200 photocell recommended for PCI The text mentions that this device is available from Allied Electronics and Newark Elec trcnics While this mav be so both sources have a minimum re quirement of 25 per order which puts building such projects be yond the reach of reasonable price May I suggest that if Modern Electronics wishes to sell maga zines in Canada full information about ICs and other devices should be given so that equivalents can be purchased here without having readers suffer the cost of postage customs etc John E Sandon Humphries Logan Lake B C Canada The CMOS op amp you refer to is a specialized device that is available in only 1 000 piece quantities The Note at the end of the Parts List gives a source from which this chip can be obtained in single unit quantity The 3914 is available from Digi Key 1 800 344 4539 among other suppliers The VT200 series was cited as a typical example of the photocell to use You can use any other photocell that has the characteristics given in the article Ed Perspective Please What is the view of the Dinsmore magnetic sensor in Fig 2 of the Digital Compass project featured in the August 1990 issue of Modern Electronics J B Craig Marysville CA The view is from the bot
5. 590 S8MM 430 305 CALL T TOLL FREE epee FREE CATALOG 1 800 338 0531 Sharp JVC and more Over 45 parts in all CIRCLE NO 89 ON FREE INFORMATION CARD IL EDITORIAL Modern Electronic Drafting Computer graphic systems have changed the way many people draw electronic schematic diagrams and create artwork for making printed circuit boards Mar rying mechanical drawing to computers is nothing new it began in the early 1960s From a hardware viewpoint it started with mainframes extending to minicomputers and then to graphics workstations In recent years personal computers have been used for this pur pose too The more powerful a PC is the more sophisticated accompanying software can be Even today s top model PCs however exhibit severe limitations in what they can accomplish in the CAD area For certain applications such as de sign work that requires solving analysis problems they re still too slow For some solid modeling uses they don t have enough memory for precise work Nevertheless for many CAD pur poses they re very satisfactory Further more their relatively modest price makes them exceptionally attractive since more engineers can have access to the machines for a host of CAD applications where they work very well In electronics they re especially effective for drafting and for printed circuit board layouts Moreover they serve well to train users for work on
6. On 4 6 oe be ew P P NB e IF SHIFT AF RF N82 wOTCH AGC LAF ATT I R y The R 2C903 UNA all MA EL receiver with 10 membry charif ls gt 5 many deluxe features such 8s dao bs mable scatining dual 24 holcclogks with times ail mode queicl nd noise blankers a large front mounted ENT speaker t0 volt AC or 12 velt DG DE operaticn with the DCIK 1cable and 118 174 MHz VHF capability with VC 10 option Optional Accessories R 2000 e VC 10 VHF converter e DCK 1 DC cable kit for 12 volt DC use R 5000 e VC 20 VHF converter VS 1 Voice module DCK 2 for 12 volt DC operation e YK 88A 1 AM filter YK 88SN SSB filter e YK 88C CW filter e MB 430 Mounting bracket Other Accessories e SP 430 Excernal speaker e SP 41 Compact mcoile speaker SP 50B Mobile speaker e HS 5 Deluxe head phones HS 6 Lightweight headphones KENWOOD U S A CORPORATION COMMUNICATIONS amp TEST EQUIPMENT GROUP P O BOX 22745 2201 E Dominguez Street Long Beach CA 90801 5745 KENWOOD ELECTRONICS CANADA INC P O BOX 1075 959 Gana Court Mississauga Ontario Canada L4T 4C2 KENWOOD pacesetter in Amateur Radio CIRCLE NO 10 ON FREE INFORMATION CARD
7. Richard A Ross Publisher Art Salsberg Associate Publisher Dorothy Kehrwieder General Manager Frank V Fuzia Controller Catherine Ross Circulation Director Melissa Kehrwieder Data Processing Kathleen Bell Customer Service SALES OFFICE Modern Electronics 76 North Broadway Hicksville NY 11801 516 681 2922 FAX 516 681 2926 Jonathan Kummer Advertising Manager Emily Kreutz Sales Assistant Offices 76 North Broadway Hicksville NY 11801 Tele phone 516 681 2922 FAX 516 681 2926 Modern Electronics ISSN 0748 9889 is published monthly by CQ Communications Inc Subscription prices payable in US Dollars only Domestic one year 18 97 two years 36 00 three years 53 00 Canada Mexico one year 21 00 two years 40 00 three years 59 00 For eign one year 23 00 two years 44 00 three years 65 00 Foreign Air Mail one year 76 00 two years 150 00 three years 224 00 Entire contents copyright 1990 by CQ Communications Inc Modern Electronics or CQ Communications Inc as sumes no resporsibility for unsolicited manuscripts Al low six weeks for delivery of first issue and for change of address Printed in the United States of America Postmaster Please send change of address notice to Modern Electrosics 76 North Broadway Hicksville NY 11801 CQ Communications Inc is publisher of CQ The Radio Amateurs Journal Popular Communications Modern Electronics CQ Radio Amateu
8. Snap the battery back into its con nector Holding S closed plug the free end of the wire connected to the anode lead of the LED make sure the two LED leads do not touch each other into pin 14 of the JC2 socket Press and release S7 If all is okay the LED should blink rapidly If it does jumpering from the 5 volt rail to pin 11 of the C2 socket should cause the LED to extinguish With the battery removed from the circuit plug the 4017 counter chip in to the C2 socket Again make sure the IC is properly oriented and that no pins overhang the socket or fold under between IC and socket Plug the battery back into its connector Touching the free end of the wire connected to the anode of the LED press and release S7 The LED should eventually flash on and then extinguish Do this for all counter outputs used to ascertain that all are working properly If you experience any difficulties during the checkout procedure dis connect the battery from the project and troubleshoot as needed Do not proceed to final installation until you have corrected any problems Once you are certain that the cir cuit has been correctly wired discon Say You Saw It In Modern Electronics nect the test LED and wires Then disconnect your telephone instru ment from the wall jack and open it up to get at the internal circuitry Drill a hole in the housing of the tele phone instrument to permit mount ing 1 in a location where it
9. 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 250 Frontage Road Slidell LA 70460 Part of a printout that gives proof that LaserTwin is properly installed and is operating correctly Heading was produced by downloading an HP software font to printer Vari ous boxes and grids shown superimposed on each other here give user an idea of what can be done with LaserTwin cluded in the manual The 106 page man ual is well written but includes just three illustrations SuperFonts 25 1 A companion program to LaserTwin and priced the same is SuperFonts 25 1 This program gives you all Hewlett Packard cartridges from A to Z It in cludes over 139 fonts all of HP s symbol sets over 14 type families and 11 type sizes that range from 6to 18 points Fonts are selected from a pull down menu Comments We used LaserT win with a 9 pin dot ma trix printer and the results were okay but not spectacular enough to warrant a 179 expenditure However Metro Software provided us with print samples from 9 pin 24 pin and ink jet printers The ink jet sample taken from an HP Desk Jet is truly impressive as can be seen in the top illustration in Fig 1 The capabilities of LaserTwin are sti fled since it
10. To make the hole pattern for slide switches position the template at the desired location with clear double sided tape Use a square or oblong shaped cutter to remove the waste material in the oblong hole in several penetrations Punch the mounting holes and remove the template Touch up the oblong hole with a small file If necessary slightly ream the two mounting holes When making cutouts for DB style connectors proceed in a similar manner When using the beveled knife for DB connector cutouts place the flat surface of the cutter against the edge of the template and make a series of overlapping penetra tions If necessary use an X acto or other hobby knife to break out the large waste slug Finish the edges of the hole with a small file For large oblong cutouts lay out the hole pat tern in pencil Place a thin metal strip along the edge of the pattern and use it a a guide as you cut the hole with the chisel knife With close observation and slight twist of the tool you can usually feel and determine full penetration of the tip through the plastic Tip penetra tion is easily felt by allowing the tip to fall through the plastic by about inch Place a Y inch thick chipboard shim under the workpiece but clear of the hole Alternatively use a sheet of dense foam plastic as a backup to readily feel and limit penetration of tip through the plastic Holes for miniature and subminia ture phone jacks are preferably h
11. ucts are included in this latest issue of the Catalog Additionally some featured products are available to the public only through the new Catalog For a free copy of the fall Tek Direct Catalog write to Tektronix Inc P O Box 19638 Dept ME Portland OR 97219 9881 Power Supply Testing Literature Two new application notes on automatic pow er supply testing from Intepro Systems detail advances made in areas of general interest to people engaged in design test ing and repair of power supplies One covers techniques for measuring a sup ply s response to transient conditions The other looks at a new type of electron ic load design that provides a much high Say You Saw It In Modern Electronics er quality of test than conventional loads For free copies write to Intepro Systems Inc Attn Mike O Connor Six Fortune Dr Billerica MA 01821 Scientific Software Catalog MicroMath Scientific Software s 1990 91 Software for Complex Scientific Problem Solving catalog highlights five of the company s scientific software products and lists nine other such products from other compan ies The 32 page color catalog gives over views of a GRAPH package that incor porates the most important features for research data presentation MINSQ for nonlinear curve fitting and model de velopment EQUIL for solution of aque ous chemical equilibrium problems LAPLACE that employs the numerical inversions of Laplace transforms and
12. 2 ampere dc full scale ammeter movement See text M2 1 volt dc full scale dc meter movement See text S1 Spst toggle or slide switch with 3 ampere or more contacts S2 Dpst toggle or slide switch with 0 5 ampere or more contacts T1 25 2 volt 2 8 ampere center tapped power transformer Printed circuit board or perforated board with holes on 0 1 inch centers and suitable Wire Wrap or soldering hardware see text sockets for IC3 and IC4 TO 3 mounting kit for Q1 suitable enclosure see text ac line cord with plug rubber grommets control knob for R7 six and two lug terminal strips thermal transfer compound small diameter heat shrinkable or plastic tubing see text lettering kit and clear acrylic spray see text 4 inch spacers machine hardware hookup wire solder etc dc units that have a dc resistance of 47 000 ohms Resistor R73 serves asa shunt for M1 A current of 2 amperes flowing through this 0 5 ohm resis tor develops 1 volt across the resistor This provides a full scale indication for MI The 1 volt range of M21s sufficient for the Lo setting of S2 For the HI setting of the switch however R74 is switched in series with the meter movement to make up a voltage di vider that changes the range of M1 to 10 volts full scale Construction There is nothing critical about com ponent placement and wire runs in 34 MODERN ELECTRONICS November 1990 WwwwWw americanradiohistorv com this
13. 6 Common CPVC plastic water pipe is a good choice for the housing of the probe assembly The ideal material is a tube that absorbs infra red energy in the 6 5 to 15 5 micron wavelength region but does not emit infrared in this wavelength band CPVC may have at least a slight ten dency to this ideal characteristic The excellent directional charac teristics of the probe assembly indi cates that CPVC absorbs most infra red energy in the 6 5 to 15 5 micron region The main circuit compen sates somewhat for the potential er ror caused by the IR emissions from the tube striking the thermopile de tector The primary error here arises if the tube is at a significantly greater or lesser temperature than the trans ducer This can occur if one holds on to the sensing end of the probe as sembly or if the probe is used in an environment where the temperature is rapidly changing In addition to being the electrical heart of the probe the 2 inch inner Install on solder side of PC board Fig 5 Actual size etching and drilling guide A for probe pc board and wiring guide B for same 1 A 28 MODERN ELECTRONICS November 1990 www americanradiohistorv com Say You Saw It In Modern Electronics LER IRS1 Leads 1 About 2 Probe PC board Conductor side 3 conductor cable A B 1 2 ID CPVC pipe i 2 ID PV e C pip C D between pipes PVC pip
14. Install a 4 inch shaft collar to grip the tubing to this adapter For the inch tip cut off a 1 inch length of inch shaft which slides freely into the inch tubing Slightly en large the hole of a A inch shaft collar to slide fit on the 2 inch tubing Use a small tubing cutter to cut rabbit ears tubing to length Cut off a 2 inch length of inch tubing and square off both ends and remove burrs With a small tapered reamer turn the working end of the tip to a knife edge Then use a high speed hand grinder such as a Mototool and a thin and abrasive cutoff wheel to cut a 4 inch long axial slot on one side of the tip to form a clean out slot Wear a face guard when work ing with the grinder Push the tip fully into the inch collet with clean out slot lined up with the setscrew of the collet collar The setscrew tells you where to find the clean out slot Cut off and pre pare a 14 inch length of inch tub ing and install in the inch collet Cut off and similarly prepare a 1 inch length of 4 inch tubing Then make a inch long axial slot at the upper end of the tip 180 degrees re moved from the clean out slot In stall the tip on the adapter with set screw aligned with the clean out slot Prepare a 1 4 inch length of inch tubing and install on its adapter Figure 2 shows X and inch round cookie cutters and two square cutters made from inch lengths of deep drawn thin wall CM EIE CA
15. MODERN ELECTRONICS FUN PROJECT BOOKS a Order both only 25 gam Plus Shippj ng Computer system power controller Duai pulse generator Surround sound audio enhancer Security telephoned status report er alarm control center Home convenience selectable phone ringer musical tunes touch sensitive light controller and so much more The Fun Projects are capped by intro ductory information on building proj ects and kits tools needed parts sources etc and advanced design techniques that illustrate how a design erthinks and plans when putting togeth er a practical end product From beginning to end MODERN ELECTRONICS FUN PROJECT BOOKS are for you Order them today for a fast start in the world of electronics Order Date QTY Title Price Total 1 First Book 12 95 ea of Modern Electronics Fun Projects Second Book 12 95 ea of Modern Electronics Fun Projects Order both books and Pay only 22 95 Plus shipping Shipping charges 2 per order Orders processed day received but please allow 30 days for delivery WwwWw americanradiohistorv com e ELECTRONI e Stocking Locations Across America CIRCLE NO 88 ON FREE INFORMATION CARD DIGITAL VIDEO STABILIZER ELIMINATES ALL VIDEO COPYGUARDS While watching rental movies you will notice an noying periodic color darkening color shift un wanted lines fiashing o
16. Take the pair of wires with the labeled ends together allow for 2 in ches of lead length and wind 10 turns of this double wire around the bob bin inthe same direction used for the feedback winding Secure this wind ing to the bobbin with Mylar tape and cut the two unmarked ends leav ing about a 2 inch lead length Carefully scrape about inch of the enameled insulation from the ends of the primary lead wires leave the labels in place Use an ohmmeter or audible continuity checker to lo cate the unidentified end of the wire connected with the one labeled 4 and label it with the numeral 5 Then la bel the remaining wire with the nu meral 6 Twist together the two wires labeled 5 to identify the center tap The phasing of the secondary win ding is not important Hence you do not have to concern yourself with the direction used to wind it onto the bobbin Simply wind 33 turns of No 32 wire onto the bobbin again allowing about 2 inches of lead length Secure this final winding with Mylar tape and mark its leads with the nu merals 7 and 8 Now inspect the shiny surfaces of the two halves of the ferrite pot core to ascertain that it is free of dirt and brote ORDER FORM Please send me the following issues 3 50 each Month s amp Year s Number ordered 3 50 each NAME ADDRESS CIL ees Total Payment Enclosed Table 3 Operating Parameters fer Design Example Input
17. YOUR ONE STOP SOURCE OF ELECTRONICS INFORMATION ICD 08559 NOVEMBER 1990 2 95 CANADA 3 95 MODERN THE MAGAZINE FOR ELECTRONICS amp COMPUTER ENTHUSIASTS m Measure Temperature Appoints MousePen Pinter 65 Without Touching m Thermal Machining Gives Plastic Project Boxes Real Professional Look Full Construction Plans m Area Code Speed Dialer B A recision Low Voltage Power Supply a s ost Jig E 2 3e DC Converters Stereo Audio Test Box p 37 ayey ying DO co 3 y 22 o wW abejsog S f G2 e rn n wo e gt N s amp s lt I gt iMMMW amedcanradiohistoruzcom SPEEO awe VSC as mi LE E t nnn ri u G Ci th thar 89 i COMMUNICATIONS RECEIVER IC R 7000 p SCAN START STOP d T ee M E SET CSET RESET C CL AUTO M 4 s ET mom ci ICOMs IC R71A and IC R7000 are the professionals choice for receiving inter national broadcasts aircraft marine business emergency services television and government bands These people demand the finest in communications and so do you ICOM puts the world at your fingertips with the IC R7000 25 2000MHz and IC R71A 0 1 30MHz commercial quality scanning receivers Incomparable Frequency Control Both the IC R71A and IC R7000 feature direct frequency access via their front keypad main tuning dial optional infrared remote control and or computer interface ad
18. sembled height of 13 mm will usually be identified by the number 2213 Cores as small as 5 mm in diameter and 5 mm in height are commonly available as are many other sizes up to 42 millimeters or more in diameter Theory of Operation To properly design the transformer for use in a dc to dc converter you must first understand how such a cir cuit works We will use the Fig 1 schematic for this explanation This circuit is simply a push pull oscillator that uses a transformer that has a feedback winding at terminals 1 2 and 3 a primary winding at terminals 4 S and 6 and a secondary or output winding at terminals 7 and 8 When power is first applied to the circuit both transistors forward bi ased through R7 This causes collec tor current to flow in Q and Q2 However since the two halves of the circuit do not perform identically the increased current in one transis tor will be greater than the other This difference in current in the pri mary winding of 71 is reflected as an induced voltage in the feedback wind ing which causes the current flow in one transistor to increase rapidly to saturation and diminishes the current flowing through the other transistor with the result that the latter transis tor is biased into cutoff When the current in the conduct ing transistor has reached its satura tion level and can increase no fur ther the magnetic field in 77 ceases to change The voltage induced in the
19. 4 08 4 47 4 5 3 9 9 20 5 48 5 52 4 16 16 24 6 32 6 36 3 525 24 40 7 07 7 11 6 36 39 20 7 95 7 22 7 49 48 20 8 37 8 42 8 64 63 20 8 94 8 90 9 81 79 80 9 49 9 50 10 100 98 70 10 00 10 05 Comparing these results with those given earlier you can see that the AD534 is ex ceptionally accurate If you have ever at tempted to calibrate a log multiplier using a 10 turn potentiometer you will be hap py to pay the 29 95 that Analog Devices P O Box 9106 Norwood MA 02062 charges for the hermetically sealed metal can version of the AD534 Single chip multipliers can be used to perform division The DIV100 divider however provides superior performance because it is designed specifically to per form division operations It can also be used to extract square roots Shown in Fig 10 is the schematic of a circuit that uses a DIVIOO to determine the ratio of the intensity of two light sources The first time I assembled this circuit its accuracy was very poor I dis covered that for best results the DIV 100 inputs should be connected to sources with a very low output resistance This re quirement was met by inserting a pair of unity gain op amp buffers between the op amps for the two detectors and the DIV100 inputs If you use a quad op amp these two buffers will already be available without having to add an ad ditional chip You can power the DIV100 from any source that delivers 12 to 20 volts For best accuracy ho
20. 4 volts 10 turns 5 volts 32 8 turns which rounded out be comes 33 turns 5 Select primary wire size by cal culating the input current and refer ring to Table 1 Input current 2 14 watts 5 volts 428 mA Each half of the primary will carry 428 2 or 214 mA average current which means that No 28 wire can be used 6 Select secondary wire size for a load current of 100 mA which means that No 32 wire can be used 7 Check Table 2 to determine if the calculated number of turns 63 total will fit on the bobbin with space to spare for the insulating layer between windings Since Table 2 in dicates that up to 200 turns of No 28 wire will fit the bobbin has sufficient space for the windings Additionally best transformer design is with the bobbin as full as possible Larger gauge wire can be used if desired to fill the bobbin and reduce voltage drops in the windings 8 Select the transistors using four times the supply potential or 20 volt minimum collector to emit ter breakdown and 428 mA collec tor current The npn 2N2222A sili con transistor meets this criteria 9 Calculate the resistance and power dissipation of RZ using Ohm s law using 10 percent of the expected input current and allowing for a 0 7 volt base to emitter drop Rl S volts 0 7 volt 0 0428 ampere 100 4 ohms and Power 5 volts 0 7 volt 0 0428 ampere 0 18 watt For this application a 100 ohm 4 watt resistor woul
21. 7C3 and its associated components make up a voltage reference source for the Power Supply Zener diode D a 9 volt 7 5 milliampere device with a temperature coefficient rated at 0 01 C serves as a very stable and accurate voltage reference which is required for the Power Sup ply to be precise under all operating conditions Op amp C3 functions here as a buffer for the zener diode With RANGE switch S2 set to its HI position the Supply s high range is selected OUTPUT LEVEL control R7 provides the means for adjusting this range from 0 to 9 volts Setting S2 to its LO position places potentiometer R7 in series with fixed resistor R6 for precision adjustment of the Supply s low range from 0 to 150 millivolts The reference voltage from pin 6 of JC3 is delivered to noninverting input pin 3 of operational ampli c QO Fig 1 The complete schematic dia S ES cae Og je ro gram of the Precision Low Voltage DC Power Supply circuitry Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 33 Aa Reread OMN a PARTS LIST Semiconductors D1 1N935 precision zener diode see text IC1 7815 15 volt regulator IC2 7805 5 volt regulator IC3 IC4 741 operational amplifier LED1 Jumbo red light emitting diode Q1 2N6057 silicon npn Darlington transistor Q2 2N3904 or similar general pur pose silicon npn transistor RECTI1 100 volt 4 ampere full wave bridge rectifier assembl
22. Circuits Handbook This 540 page book describes multiplication division squar ing rooting log and antilog circuits rms to dc conversion and much more Though first published in 1976 the basic principles it describes have not changed Nonlinear Circuits Handbook is avail able for 5 95 from Analog Devices With the knowledge you gain from this book and a handful of precision multipli SQUARE ROOTER DbivibER Fig 9 Details of how arithmetic operations are performed by configuring an AD534 mul tiplier chip in different ways Higher accuracy versions are available at greater price Burr Brown has a 75 mini mum purchase requirement Therefore that is willing to accept single unit orders Alternatively you may want to purchase three or more chips from the ample Burr er and divider chips you can design a very sophisticated analog computer that can perform wonderfully complicated try to find a Burr Brown representative Brown catalog of analog ICs calculations in real time ME Ri iM T n 412 q4 ze 19 Vv a 13 PDL ae 15 iH KJ gt RZ Div 100 fo up AA 2 Pp2 D G 110 3 1Sv i ut 5 1l z T PD2 BYPASS 45 V With LOAF AND 1000 pF TO GROUND Fig 10 This ratiometric light detector circuit is built around a DIV 100 divider chip Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 61 Wi SOLID STATE DEVICES EEE Error Detection amp Co
23. Combined with zero switching and grounding from tip to plug the Model 9910HC is claimed to be ideal for working on voltage sensitive components Additionally the 24 volt iron features a long life break resistant ceramic heating ele ment and a cool ergonomically de signed grip for operator comfort Three additional quick connect irons with a wide variety of tips to customize the station to different sol dering applications are also available CIRCLE NO 64 ON FREE INFORMATION CARD Network Management Workstation System According to Frederick Engineering Inc Columbia MD you can now manage a network with a little bit of everything on it with its FECOS network management system The system provides information collec tion monitoring and control and permits consolidation of eight com Say You Saw It In Modern Electronics munication applications into one platform via a multitasking win dowing environment running on an 80386 DOS based platform FECOS consolidates control of eight different pieces of equipment into one platform and permits screens to be adjusted to suit the re quirements of each application It collects and processes alarms and events from different communica tion equipment Alarms and events arelogged in a SERMON Status ER ror MONitor window with cor rectiveaction taken through FECOS The system also provides local and remote dateline monitoring and pro tocol analysis for wi
24. Designing the Circuit You now have sufficient information to design your own dc to dc con verter circuit Let us do so now using the practical design example shown in Fig 6 The circuit to be discussed is a dc to dc converter powered by a 5 volt source to produce a 15 volt dc output This is a common applica tion for digital logic systems that operate with a power source of 5 volts dc that also include analog cir cuitry that requires a higher voltage For our design example assume the output of the dc to dc converter is 15 volts dc and delivers a load cur rent of 100 milliamperes into a 150 ohm load The design sequence would be as follows 1 Calculate the input power of the circuit assuming 70 percent effi ciency P 15 0 1 0 7 which calculates out to 2 14 watts 2 Select a pot core size from Fig 3 at a 10 kHz operating frequency porated into an actual project from the data given a 22 x 13 mm core is suitable but an 18 x 11 mm could also be selected 3 Calculate the number of turns for each half of the primary winding of the transformer using 2 000 Gauss flux density and an effective core area of 0 63 sq cm for the 22 x 13 mm core Np 25 x 106 5 0 63 2 000 10 000 9 9 turns Thus each half of the primary will have 10 turns 4 Calculate the number of second ary turns for a 15 volt output taking into consideration a 1 4 volt loss for the bridge rectifier diodes N 15 volts 1
25. EDC single bit errors can be corrected on the fly and the processor can continue to process data without interruption An other consideration is component over head In a byte parity scheme 32 bit data requires four parity bits and 64 bit data requires eight parity bits With EDC 32 bit data requires seven check bits a slight premium over the parity scheme With 64 bit data only eight check bits are needed for the Hamming code the same overhead as implementing parity but with the added benefit of performing error correction As memory systems go to wider memory buses from 32 to 64 bits and beyond for increased bandwidth EDC will supersede parity as the pre ferred method of memory checking Lithium Kickstarter Chip Dallas Semiconductor 4350 Beltwood Pkwy S Dallas TX 75244 has intro duced the DS1239 MicroManager a chip Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 63 SOLID STATE DEVICES with special circuitry that cold starts a computer from the keyboard instead of a circuit breaker switch Cold starting a computer with a kick from a lithium energy source moves the point of control to the keyboard so that users need not reach to the back of the system or under the table to turn it on In addition to convenience the DS1239 en hances safety by keeping 110 220 volt ac power cabling distant from the person ac tivating the switch UL and CSA VDE approval
26. LITHIUM DALLAS NZa DS1239 ene cee i MANAGER T Jt TRIAC 4 110 220 VAC LOW HIGH E VOLTAGE VOLTAGE Fig 2 Dallas Semiconductor s DS1239 MicroManager chip cold starts a computer from the keyboard rather than from a rear or under table mounted power switch the Hamming code generation and checking for correcting memory errors During a write to memory cycle a check bit word is generated for each data word by the EDC circuit For 16 bit data six bits are needed for a check bit word Sev en bits are needed for 32 bit data and eight bits are needed for 64 bit data words On a read from memory cycle the EDC circuit reads both the data word and the check bit word A new check bit word is then generated and compared ORed with the original check bit word Syndrome bits generated by the com parison of the two check bit words indi cate whether the data is error free or if there is an error Additional circuitry on the EDC can determine from the syn drome bits which single bit is in error and correct that data bit The corrected data then becomes available in the data out put All double bit errors and most triple bit errors can be detected with the syn drome bits and an error flag generated If a parity error checking scheme is used single bit errors can be flagged but not corrected Therefore the error must be handled with an interrupt to the main processor for arbitration Using
27. Low Voltage Precision DC Pow er Supplv Therefore you can assem ble the project using any traditional wiring method If you wish you can design and fabricate a printed circuit board on which to mount and wire together the activecircuitry Alterna tively you can use perforated board that has holes on 0 1 inch centers and suitable Wire Wrap or soldering hardware Whichever way you go however be sure to use sockets for IC3 and C4 Not all components mount on the circuit board Those that do not in clude the POWER and RANGE switches relay power transformer LED me ter movements OUTPUT LEVEL con trol bridge rectifier some resistors R1 R2 R6 and R12 through R15 and capacitors C7 C2 C4 C5 and C7 and transistor QJ Once you have decided upon which type of circuit board you will use install and solder into place the IC sockets Follow up with the voltage reguiators zener diode and transistor Q2 Take care to properly orient these devices before soldering any leads or pins into place Then in stall and solder into place the fixed resistors capacitors and trimmer potentiometer Prepare 10 8 inch lengths of strand ed hookup wire by stripping inch of insulation from each end Tightly twist together the fine wires at all ends and sparingly tin with solder Solder one end of each wire into place on the circuit board for connec tion later to off the board compo nents The completed circuit board assembly wire
28. Output 5 0 volts 14 1 volts 390 mA 94 mA 150 ohm load 1 9 watts 1 3 watts Efficiency 68 percent Operating 6 450 Hz frequency Three sets minimum order of size 2213 port core bobbin assemblies are available for 25 from A Caristi 69 White Pond Rd Wald wick NJ 07463 Add 2 50 to cover postage and handling New Jersey residents add state sales tax foreign particles that would interfere with the mating of the pieces Place the bobbin between the two cores like a sandwich and carefully secure the two halves of the transformer to gether with tape Use a small machine screw with a fiber washer between screw head ana core and nut and core and nut to hold together the core Do not over tight en the screw too much pressure will crack the ferrite and render it useless Youcan now install the transform er in the circuit for which it was de signed to check out operation Should the output voltage of the transformer under load conditions prove to be greater or less than de sired you can reduce or increase the number of turns on the secondary as needed to bring the voltage in line with the needs of the circuit Once you wire the circuit shown in Fig 6 using your newly made trans former you should obtain the results given in Table 3 From the foregoing it should be Obvious that designing with and us ing dc to dc converters in power sup ply designs is both practical and easy to do By implementing such circ
29. RSTRIP compartmental modeling and pharmacokinetic analysis Other prod ucts mentioned include MathCAD CSS PrintAPlot MathEdit PROQube GAUSS PC Tools DERIVE and Frac Tools For a copy write to MicroMath Scientific Software P O Box 21348 Salt Lake City UT 84121 0348 New AOR Receiver 400 Channels 100KHz to 2036MHz Continuous coverage AM FM wide band FM LSB USB CW modes 4 Scan Banks Programmable Attenuator T F Fai Pes IFxpsss Sr tp GUI 995 Tuning increments as low a 50Hz Search with lock out 15 front end filters HS232 port built in 25 Day Satisfaction Guarantee Full refund if not Satisfied Includes AC DC power cord Telescope Antenna Size 27TH x 5 AS Wx77 8 D Wt tb 1002 COMMUNICATIONS 10701 E 106th St Indpls IN 46256 vn Toll Free 800 445 7717 i Mast rd WOT sia gEtoyv Tube qi FAX 317 849 87534 eim CIRCLE NO 77 ON FREE INFORMATION CARD AMAZING SCIENTIFIC amp ELECTRONIC PARTS ARE IN STOCK um a PLANS ANTI GRAVITY GENERATOR 10 00 40 WATT BURNING CUTTING LASER 20 00 HI POWER PULSED DRILLING LASER 20 00 1 MILLION VOLT TESLA COIL 20 00 HI VELOCITY COIL GUN ooo 15 00 LASER LIGHT SHOW 3 METHODS 20 00 ELECTRONIC HYPNOTISM TECHNIQUES 8 00 LOWER POWERED COIL GUN LAUNCHER 8 00 JACOB LADDER 3MODELS 10 00 SEE IN THE DARK ec omes 10 00 LEVITAT
30. STATE ZIP Accredited by the National Home Study Council 5414 110 LIlllllllll WWM_americanradiohistorv com NEW PRODUCTS om pase 10 voltage is also automatically mea sured by the 75 series only Accesso ries provided with these DSOs in clude two probes 1 x 10 switch able and for the 75 series only a 64K IC memory card and an IC dum my card The Models VC 6075 4 195 and VC 6065 3 995 feature 12 5 MHz single shot bandwidth and 50 MS s sample rate The Models VC 6175 4 695 and VC 6165 4 495 up the ante to a 25 MHz single shot band width and boost sample rate to 100 MS s Finally the models VC 6275 4 995 and VC 5265 4 750 boost the sample rate to 200 MS s Avail able options include an IEEE 488 interface card and GPIB cable DADisp V 1 05B and V 2 0 signal processing software for use in IBM PCs and compatibles IC card read er writer high speed PC transfer in terface color plotters IC memory card etc CIRCLE NO 53 ON FREE INFORMATION CARD Frequency Counter Timer ZTEST Electronics Inc Mississau gua ON Canada is now marketing the Myoung Model RUC 1300 reci procal universal frequency counter timer The eight decade instrument Offers three input channels two with 100 MHz range and a third with a 1 3 GHz range The RUC 1300 mea sures frequency period period aver aging time interval ratio and sum difference of two channels and total izes Reciprocal techn
31. Sales esussuncEE RIS 17 Cable Connection unm 78 Cable Mate Inc DOTT 79 Cable Plus Le 80 Cleveland Inst of Elec Cov III Command Productions 64 80 Consolidated Electronics 72 Cook s Institute oe 9 4929292922929 955209 56 99099929299 20209 tw svete eee 9 9 9 9 s 9 9 9 s oe 95 92 99 9 6 90929292929 29209292292 9 9 299 292929209 9 9 99 sen 9989990992929 852599 9 99 s 9 9 9 TCoiaste se eS Rapid Kelvin Electronics 79 10 Kenwood Cov IV Lindsay Publications 23 Listen Electronics 80 87 MCM Electronics _ 9 88 Mouser Electronics 71 NRI Schools ee 13 74 PMC Electronics 82 Pacific Cable Co Inc i 223 89 Parts Express International 8 75 Phototronics 9 43 Republic Cable 80 90 SCO Electronics se 71 9 Sescom Inc 27 Oe udi Skyvision ESI e BENSE P Trans World Cable Co US Cable own Video Tech e 97 98 Viejo Publications 67 81 Visitect Inc ee 80 Weka Publishing We d like to see your company listed here too Contact Jonathan Kummer at 516 681 2922 to work out an advertising program tailored to suit
32. The VHF converter options must be used in the R 5000 and R 2000 R 5000 The R 500C is a high performance top of the line receiver with 100 memory channels aad direct keyboard or main dial tuning makes station selection RZ 1 Wide band scanning receiver The RZ 1 wide band scanning receiver covers 500 kHz 905 MHz in AM and narrow Or wideband FM The automatic mode seiection function makes listening AM TOHMUNIZATIONS RECEIVER MODE KEY RESET mm MINUTE TU K ENT I super easy Other useful features include programmable scanning large built in speaker 110 volt AC or 12 volt DC operation with optional DCK 2 cable VHF capability 108 174 MHz with the VC 20 option dual 24 hour clocks with timer and even voice frequency readout with the VS 1 option easier One hundred memory channels with message and band marker direct keyboard or VFO frequency entry and versatile scanning functions such as memory channel and band scan with four types of scan stop The RZ 1is a 12 volt DC operated compact unit with built in speaker front mounted phones jack switchable AGC squelch for narrow FM illuminated keys and a beeper to confirm keyboard operation Optional Accessory e PG 2N Extra DC cable Specifications features and prices are subject to change without notice or obligation WWW americanradiohistorv com HF VHF NB1 CLII MHZ fi BH Lad page pee SQL S NOTCH
33. as shown When the cement has fully set loosely twist together the positive lead of C5 and the case lead of IRS and solder the connection This assures that C5 measures the refer ence junction temperature of 7RSI You should use a printed circuit board on which to mount the RS7I IC5 combination and wire to it the cable that connects the probe assem bly to the main circuit Fabricate this board with the aid of the actual size etching and drilling guide shown in Fig 5 A Once the board is ready mount the RS1 IC5 assembly on it as shown in Fig 5 B Now remove inch of outer plastic jacket from both ends of a 24 to 36 inch length of three conductor cable preferably with insulation color cod ed red green and black Twist to gether the exposed fine wires in all conductors at both ends of the cable and sparingly tin with solder Plug the conductors at one end into the holes specified in Fig 5 B and solder them into place Note that the cable NOTE IRS1 IC5 combination A IRS1 case lead and IC5 cathode lead B IRS1 lead C IC5 anode lead D IRS1 lead 1 Red lead 2 Green lead 3 Black lead Three conductor cable from main circuit conductors plug into the copper trace side of the board The internal structure of the probe assembly consists of a 12 inch length of a inch inner diameter CPVC plastic pipe and the small pc board used to mount the detector transducer assembly as shown in Fig
34. be operated is limited only by the ratings of the components being used Some practical applications for this project include operation of ventilation fans solenoid controlled water valves outdoor house lighting and keyless door locks space heaters radios night lights and table lamps etc About the Circuit Most resistive devices powered from the 117 volt ac line can be controlled using the AC Interface circuit shown schematically in Fig 1 This circuit is operated by a menu driven PSWITCH BAS computer software program written in BASIC and shown elsewhere in this article The source code may be compiled to per mit self execution and eliminate the need for the BASIC program The program tells the computer to raise or lower the logic levels of its eight parallel data lines For the following explanation we will use Channel 1 of the circuit Any other channel can just as easily be used for this purpose since all eight channels are identical in design and operation except that each is accessi ble by a different code from the key board of the computer being used Instructing the computer s parallel port to raise a data lineto logic level 1 5 volts dc forward biases the gal 40 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com omputer tontrolied AC Interface Simple interface circuit and BASIC program let you control lights and other 7 appliances from the keyboard Of your I
35. bit timer counter control channels and one eight bit event counter Three eight bit 10 volt dc chan nels are provided as are one eight bit 10 volt ac channel and one eight bit 0 to 10 volt dc D A converter The function generator provides sine square and triangular waveforms with sweep input A separately avail able power pack provides 12 and 12 volts both at 250 mA and 5 volts at 500 mA The device measures 7 6 x 3 5 x 1 3 349 95 34 95 power pack 3 demo disk CIRCLE NO 51 ON FREE INFORMATION CARD Shelf Size Stereo System Yamaha Electronics Corp has a compact stereo system that utilizes Active Servo Technology to achieve low and accurate bass response from small speakers The Model YST C11 consists of an Active Servo Technol ogy amplifier AM FM stereo tuner CD player dual cassette decks four band graphic equalizer and detach able stereo speakers The amplifier employs various types of matching and feedback circuitry to produce ex tremely low and accurate bass re sponse from speakers with a foot print of only 5 by 97 inches The CD player at the top of the console unit offers direct random and programmed access It features a 20 track calendar track selection keypad intro scan auto replay syn chronized to the cassette deck for re cording and built in timer for wake up purposes An EQ record on off cassette deck function permits adjustment of the tonal qualities of the s
36. feel free to modify the adap tersto suit your own particular needs Adapters for 4 and X inch tips shown at left in Fig 1 are two sided collets For the inch tip adapter use a 1 inch long by 4 inch diameter seamless spacer with 4 inch through hole Grip the spacer vertically in a vise Then use a fine toothed hack saw to cut a 4 inch long slot length wise to form a two sided inch col let Slip a 4 inch shaft collar over the slit portion with setscrew positioned 90 degrees from the slot Use the same size spacer to make a inch collet for the inch tip Using a inch drill bit enlarge the 4 inch hole in the spacer to a depth of 14 inch Slot the drilled portion to form a two sided inch collet Then install a inch shaft collar on the collet Adapters for the larger and 4 inch tips shown at the right in Fig l utilize 4 inch solid shafts Make the Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 19 ahi adapter for the inch tip from a 1 inch length of shaft Chuck 7 inch of the shaft into a inch drill Slip a washer with inch hole on the protruding end of the shaft to protect the drill chuck At low to medium drill speed and using a flat file re duce shaft diameter until the inch tubing slides onto the shaft Check frequently as you file using the tub ing as a gage When the diameter is about right use a finer file and finish up with No 240 sandpaper
37. future techni cians and make life easier for technicians whose specialty is consumer TV receivers gt CIRCLE NO 70 ON FREE INFORMATION CARD 72 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Say You Saw It In Modern Electronics and monitors projection sets and VCRs It presupposes that the reader has some familiarity with the fundamentals of elec tronics and hands on experience working with circuits and test equipment To adequately cover the range of cir cuitry used in modern consumer video equipment the book is divided into 22 chapters Most discuss circuitry from the TV receiver point of view However since VCRs use identical or similar circuitry plus specialized recording and playback circuitry what one learns from the TV re ceiver section is applicable to the VCR Because it is meant to serve as a train ing aid as well as a reference for experi enced personnel the book begins with five general chapters on the basics of the TV system TV receivers electronic com ponents test equipment and servicing aids and basic troubleshooting and re pair techniques The remainder of the book is largely a blow by blow descrip tion of the various circuits that make up the TV receiver with each circuit type as signed its own chapter a separate chapter deals with digital TV monitors and pic cure enhancement and another chapter at the end of the book is devoted to pro jection TV Within each c
38. hard error is a permanent error in the hardware that causes the data bit to be stuck at one or stuck at zero Soft data errors om the other hand are ran dom and unpredictable Sources of soft data errors are transmission line effects power surges pattern sensitive memory cells and alpha particle radiation o 62 MODERN ELECTRONICS November 1990 iab Say You Saw It In Modern Electronics As systems operate at clock speeds in excess of 25 MHz system noise and pow er surges become increasing concerns to the system designer Also as state of the art memory technology gives us sub micron features susceptibility to alpha particles flipping a memory bit is almost certain to increase Historically parity checking has been the preferred method for detecting errors in data due to its simplicity of implemen tation Parity is generated by counting the number of data bits that are high and assigning a parity bit to make the total either an even or odd number of high bits There are two parity conventions used even and odd Even parity desig nates a low on the parity output bit if there are already an even number of data bits that are high If an odd number of data bits are high then a high is desig nated on the parity bit On the other hand odd parity designates a low on the parity bit if there are already an odd num ber of data bits that are high The parity bit is high
39. if there is an even number of data bits high Parity has the advantage of detecting errors very quickly in 12 ns for a chip like the AS280 Implementing parity does not require a large number of external components a parity checker generator like the AS280 and the additional memo ry used to store the parity bits Systems generally implement byte parity with a separate parity bit for each eight bits There are two Significant down sides to parity checking Firstly there may be cases when more than one bit gets flipped from high to low or low to high If two bits get flipped two bit error the sense of the parity remains the same even though the data is in error So parity is not a fail safe error detection mechan ism Secondly when a parity error gets flagged the system must intervene and decide what to do with the erroneous data Should it ignore the error Should it try to receive the data again In either case a decision must be made by an arbi trator ultimately slowing down system throughput Hamming Code To the Rescue Developed by Bell Labs in the 1950s a Hamming code is capable of not only de tecting all single bit errors but also of correcting those bits to their original sense In addition the Hamming code de tects all double bit errors and most triple bit errors The EDC circuits from IDT implement SYSTEM POWER a TO COMPUTER SUPPLYG 3 3 i OPTO ISOLATOR r9 a 7
40. in my work to enjoy them very much in my spare time But I find myself booting up Life amp Death pret ty often It s challenging entertaining and educational at the same time I just wonder if there sany way I could get a set of MD plates for my car now The MousePen Many of today s applications such asthe game reviewed here require some sort of oe x E pointing device The mouse has become the most popular of them with millions having been sold In previous columns we ve taken a look at some of the avail able alternatives including trackbalis FELIX the friendly pointer and Cal Comp s WIZ mouse digitizer All were interesting but none have quite taken the place of my trusty old soap bar Micro soft mouse l ve been using something the last few months that might actually displace mv mouse from its desk space the Appoint MousePen True to its name the Mouse Pen looks like a ball point pen with a werv thick barrel and a snout The snout is E Da ER Bos Lo Appoint s MousePen as its name implies is a mouse pointing device housed in a pen like enclosure Handled in much the same manner as you would a pen marker this device re quires very little desk space to operate and hardly any learning time at all 66 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Say You Saw It In Modern Electronics bent at about 135 degrees to the body of the pen and contains a small plas
41. includes only two common fonts If you really want to produce nice looking printouts you ll have to purchase additional soft fonts Keep in mind how ever that one of the benefits of Laser 70 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Twin is that it allows you to use the wide assortment of commercial soft fonts such as Bitstream Fontware designed for use with the HP Series II laser printer Another benefit of LaserTwin is that it lets you print sideways without purchas ing a special program Conclusion At 179 for LaserTwin and another 179 for SuperFonts 25 1 these aren t pro grams you purchase on a whim Having access to HP Series II capabilities is cer tainly a big plus but best output comes from an ink jet printer like the HP Desk Jet And if yeu purchase a DeskJet and the two Metro packages you ll probably pay more than you would for one of Hewlett Packard s low cost laser print ers or an HP compatible If you already have a DeskJet or a 24 pin dot matrix printer you might well consider investing in LaserT win especi ally if you find yourself frustrated by the limitations of your printer in terms of font support If you have a 9 pin printer however you may not be satisfied with the print quality in relation to the price you have to pay for it CIRCLE NO 70 QN FREE INFORMATION CARD Say You Saw It In Modern Electronics They re Here Wi You ll want these
42. model Appoint 1332 Vendels Circle Paso Robles CA 93446 805 239 8976 LEARN VCR CLEANING MAINTENANCE REPAIR EARN UP TO 1000 A WEEK WORKING PART TIME FROM YOUR OWN HOME Secrets Revealed NO Special Tools or Equipment THE MONEY MAKING OPPORTUNITY OF THE 1990 S IF you are able to work with common small hand toois andare 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 upto 90 of ALL VCR malfunctions are dueto 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 Viejos 400 PAGE TRAINING MANUAL over 500 photos 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 opera tion FREE INFORMATION CALL TOLL FREE 1 800 537 0589 Or write to Viejo Publications 5329 Fountain Ave Dept ME Los Angeles CA 90029 CIRCLE NO 97 ON FREE INFORMATION CARD November 1990 MODERN ELECTRONICS 67 W SOFTWARE FOCUS iii Bridging the Gap Between Dot Matrix and Laser Printers By J
43. mount the battery to the housing of the telephone instrument with which the Speed Dialer is being used You can also use double sided foam tapeto mount the circuit board assembly insidethe instrument in any location where it will not interfere with the phone If you built more than one Speec Dialer and housed them inside a sep arate enclosure you can also use double sided foam tape to mount them in place Alternatively use 2 inch spacers and suitable machine hardware for mounting purposes Wire the power lines to the various circuit board assemblies taking care to observe proper polarity in all cases Then mount the switches in their various holes and label each with the appropriate area code Set any potentiometers to their center of rotation Plug the tele phone instrument back into its wall jack make sure the handset is on hook Lift the handset off hook and press the button on the Speed Dialer while listening through the handset You should hear the digits of the area code being automatically dialed At the end of the dialing sequence you should hear an open line which now allows you to complete dialing a number to that area code The potentiometers are used to set dialing speed If the dialing speed is too fast for your telephone company to handle adjust the settings of the pots Check each Speed Dialer in turn for proper operation ME PA residents add 6 sales tax SATISFACTION GUARANTEED Il
44. of 179 Installation amp Use To install LaserTwin you simply put a disk labeled Master Disk 1 into your floppy drive and type FIRSTIME The installation program then prompts you through the necessary procedures to get LaserTwin up and running Unfortunately when you first run the program by typing LT at the DOS prompt you get a message informing you that you have acopy of the product that is not registered The message isn t so bad but if you don t register right away and get your secret code number from the company a two line trademark message is printed across every page you print with the program During the installation process you se lect a printer from a long list of popular models If you don t see your printer on the list you can use a compatible printer or call the company to find out the latest additions to the list We used LaserTwin with a Juki Model 5510 dot matrix print er which is not on the list However the Model 5510 is compatible with the Epson Model FX 80 which listed During installation you also choose boot up conditions This is done to emulate the front panel settings on the HP Series II laser printer which allows you to change such things as the symbol This drawing was done in AutoCad The call out was j done in Ventura Publisher iP B set the type style and the orientation of the boot up font LaserTwin includes a print spooler which you set up du
45. operation of the project Construction This is a very simple project to build thanks to the small component channel count Therefore you can use any traditional technique to mount and wire together the compo nents If you wish you can design and fabricate a printed circuit board for the components selected Alter natively you can mount the compo nents on perforated board that has holes on 0 1 inch centers using Wire Wrap or soldering hardware and point to point wire them together When laying out your circuit leave plenty of room for the components and future expansion the latter as suming that you are assembling less than the maximum of eight channels It is a good idea that whatever the wiring technique you use sockets for the optical isolators Wire together the components ac cording to Fig 1 When you are fin ished wiring the circuit board assem bly strip inch of insulation from both ends of as many heavy duty stranded hookup wires as are needed to connect from the triacs to the acre ceptacles If you wish you can sub stitute medium duty zip cord in place of individual wires Tightly twist to gether the fine conductors at both ends of all wires and sparingly tin with solder Then connect and solder one end of each wire to the appropri ate points on the circuit board Next use 10 conductor ribbon ca ble to wire to the free ends of the re sistors that go to the anodes of the LEDs inside the opt
46. or 3 inches square In fact the MousePen Pad now included with the device is a 2 inch square pad of paper The Mouse Pen like many other recent mouse intro ductions is ballistic in nature If you move it fast the cursor on the screen moves farther for agiven mouse distance When moved slowly however the dis tance you cover moving the MousePen and that covered by the moving screen cursor more evenly correspond Best of all the MousePen just feels good in use Holding it feels the same as holding a large pen or marker and using it feels the same as writing There s very little learning curve until you feel comfor table with the MousePen you already know how to use it Appoint states that its research indicates that the MousePen may be particularly useful for those who suffer from carpel tunnel syndrome a pinched nerve in the wrist The company doesn t however say if day long users of the MousePen tend to suffer from writ er s cramp I m still not sure that there s any such thing as the perfect pointing device but having used the MousePen for the last couple of months I think Appoint has come the closest to it yet If you re in the market for a new or your first mouse do take a look at the MousePen ME PRODUCTS MENTIONED Life amp Death 49 95 The Software Toolworks 4470 Redwood Hwy San Rafael CA 94903 415 883 3000 MousePen 149 95 IBM models 129 95 Apple DTB
47. reach be yond 25 and 33 MHZ 64 bit wide memo ry buses will become increasingly more common In 64 bit system buses alterna tive parity type error checking requires eight bits to implement The IDT49C465 also requires eight bits to implement However it also allows errors to be cor rected not just flagged Using modified Hamming code devel oped at AT amp T Bell Labs the IDT49C465 can detect all single bit hard and soft er rors and correct them within a single cy cle Double bit errors can be detected 100 percent of the time while triple bit errors MD Checkbit Generator MLEL 5 C8le 7 ED PCBI 0 7LY Control SD 0 310 a Pipeline Latch HE x o SLE LD PLE 3 Control 0 31 S MD Latch Memory Generator E r o ua i m D T Syndrome System Checkbit Generator Mux pube 3 Control Fig 1 Integrated Device Technology s IDT49C465 32 bit fiow through error detection and correction chip features a system data latch for pipelined reads from memory can be detected more than 50 percent of the time The IDT49C465 also features a built in system data latch see Fig 1 for pipelined memory system designs that al low pipelined reads from memory The IDT49C465 is available in a 144 pin grid array PGA In large OEM quantities the 20 ns correct time IDT49C4065 sells for 92 40 Integrated Device Technology also an nounced speed up of two other EDC cir cuits t
48. required for mount ing some components is done by tedi ously drilling many small holes and filing the slippery plastic You can simplify machining of polyvinyl project boxes with a few thermal punching tools that you make vour self In this article we will describe how to make these tools from readily available materials The materials you need are brass tubing from TV rabbit ears antennas for thermal punches and inch alu minum or brass shafts couplers and hubs Youcan easily make and adapt these tools to a small soldering iron which provides the heat source Hole sizes vary from under to 4 inch in diameter for use on thermoplastics up to X inch thick Rounding out the assortment of cutters you can make chisel knives and square and rectangular cutting tips You will dis cover that combined with conven tional machining methods thermal machining can simplify installation of components in thermoplastic proj ect boxes Plastics amp Machining Common plastics fall into two gener al categories Most of the plastics you will encounter are members of a wide variety of thermoplastic resins such as ABS polyvinyl acrylic and sty rene Thermoplastic resins are injec tion molded under heat and pressure to form the enclosures used for con sumer electronic products various small electrical appliances and house ware items to name a few 18 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com
49. spreadsheet sideways you just add the command LAN to the file These commands can also be sent from the DOS prompt by preceding them with the command SENDLT If you have never used an HP laser printer you might find some of its quirks disconcerting For example if you con figure Lotus 1 2 3 for the HP Series II you ll find it works differently than it does with most dot matrix printers To cite one if the spreadsheet you try to print is less than a page in length nothing happens when you press GO The HP Se ries lI won t start printing until you hit Page a formfeed in 1 2 3 Also you don t get condensed type with the fami liar 015 string You ll have to use HP laser commands instead which are in Say You Saw It In Modern Electronics Double your income NEN LN Computer maintenance service AIL d a 10 billion industry If you are presently servicing office machines or any other electronic equipment computer repair can double your income National research results indicate that computer technicians bill out at double the hourly rate of office machine technicians Tech Serv can put you into computer repair quickly economically and efficiently and with a complete support program including a proven marketing plan We provide RECOGNITION Nationally recognized trademarks and logos give you immediate recognition as a professional computer repair specialist Level 1 by be
50. you can see from the following data Input Output volts volts 0 001 0 001 0 010 0 006 0 100 0 111 1 000 205 10 000 11 490 As this table quickly reveals log and anti log amplifiers are subject to serious er rors The most important error source is temperature changes in the 2N2222 tran sistor that serves as the nonlinear feed back element Another is the offset volt age of the op amp itself When the input voltage to the op amp is very small the November 1990 MODERN ELECTRONICS 59 ELECTRONICS NOTEBOOK offset voltage can cause substantial but predictable errors Some op amps are equipped with offset adjustment pins that permit the offset voltage to be trimmed to zero when the input is con nected to ground Still another source of error is the op amp s bias current 741 op amps like those I used to assemble the circuits shown in Fig 4 and Fig 6 have a bias cur rent that ranges from 80 to 500 nanoam peres This error can be reduced signifi cantly by means of bias current potentio meter R2 A better way is to use one of the newer high performance op amps that have very low bias current One way to significantly reduce these and other errors is to mount all compo nents of the log amplifier on a common substrate for temperature control and use laser trimmed resistors for high accu racy Several manufacturers make log amps in just this fashion Multipliers amp D
51. your needs Phonvu Videophone in a Chip STILL FRAME TV PICTURE TELEPHONE TRANCEIVER KIT Sends Slow Scan TV pictures over The phone line in Twelve Seconds Captures any TV Camera Camcorder VCR NTSC Video output and holds the display and sends on command Auto Mode allows hands free sand and receive Displays on any TV IC Chip Replaces 150 SS Dips 50 Levels TE REFER of Grey Scale A i Serves as JEM TV FAX LO j 200 x 2425 Camera High Res 50 000 Phonvu Piee Videophone Chip 48P DIP ZO Y and Schematic 598 95 Mon A D DRAM D Reg 3500 Line PC Board BARE 18 95 50 Res Cap Diode 28 75 Cabinet uncut 12 75 Use Power Pack 3 75 VCR KIT PRICE 164 A 2 500 ASSEMBLED EIET3 and FAX Order 213 827 1852 _ P M C Electronics Box 11148 Marina Del Rey CA 90292 CIRCLE NO 74 ON FREE INFORMATION CARD More QSO s when you speak their language e Add extra spice to your DX QSO s e Let your DX friends know you care enough about them to learn their language After all they ve gone out of their way to learn English e Break the phone pile up with a few carefully chosen words in the DX station s own language You ll be amazed at the difference It s like adding 3 dB to your signal The Radio Amateur s Conversation Guide by OH1BR and OH3BAD gives you the 147 most often used phrases in eicht languages English Germ
52. 0 FAN COMM INT L CATALOG Over 350 Kits Plans Books about Licensed unlicensed AM FM broadcasting Ham CB SW DX amplifiers 1750M transmitters Surveillance devices Computers Software Science Pro jects MORE 1 00 refundable Box 130 ME11 Paradise CA 95967 HUGE COMMUNICATIONS CATALOG 88 pages including amateur shortwave and scanner equipment Universal Radio 1280 Aida Drive ME Reynoldsburg OH 43068 GRE Super Converters 8001 60 95 8002 75 95 P P D Send remittance Woolf Mail Order Box 630306 Ojas FL 33163 FL 6 T SALE _ USED Technical Books radio electronics math military magazines catalogs etc large list 1 00 stamps ok software Dept ME 1515 Sashabaw Ortonville MI 48462 LOW COST Ham gear Send stamp for list WA4DSO 3037 Audrey Dr Gastonia NC 38054 LOTTERY IBM COMPUTER DISK FOR ALL LOTTERIES 10 00 ROBERTS Box 63 6025 MARGATE FL 33063 DESCRAMBLERS All brands Special Combo Jerrold 400 and SB3 165 Complete cable descrambler kit 39 Complete satellite descrambler kit 45 Free Catalog MJO IN DUSTRY Box 531 Bronx NY 10461 0208 ZENITH DESCRAMBLERS _ ZENITH cable boxes will work where others failed All units are warranted with remote control 175 00 Call 213 478 2506 CABLE TV EQUIPMENT CABLE TV converters and descramblers dis count center Jerrold Tocom Hamlin Scien tific Atlantic Oak Zenith Order your
53. 0 for additional boldface words Non Commercial Rates FREE to subscribers as space permits maximum 15 words A recent MODERN ELECTRONICS mailing label must accompany ad All advertisers with P O Box addresses must supply permanent address and telephone number Copy is subject to publisher approval Mailing Information Copy must be received by the publisher by the 25th of the third month preceding the cover date Send Advertising material with check or money order or credit card information Visa or MasterCard only with number and expiration date to MODERN ELECTRONICS Classified Department 76 N Broadway Hicksville NY DP PICKS UP A WHISPER 50 FEET AWAY The model WAT 50 miniature FM tranmitter uses a 4 stage circuit NOT to be confused with a simple wire less microphone Simply snap the unit on top of a 9V battery and you can hear every sound in an entire house up to 1 mile away Use with any FM radio Tunes to any frequency from 70mhz 130mhz Easy to assemble kit includes all parts and instructions Only 29 98 tax incl The WIRELESS TELEPHONE TRANSMITTER model WTT 20 is only about the size of a dime yet transmits both sides of atelephone conversation to any FM radio with crystal clarity Completely automatic Uses power from the telephone line itself never needs a battery Up to mile range Tunes from 70mhz 130mhz Easy to assemble kit includes all parts and instructions On ly 29 98 tax incl Call or s
54. 0 FAX 702 565 4828 CIRCLE NO 91 ON FREE INFORMATION CARD SWE TESLA BOOKS PC A SS INCREDIBLE BOOKS i lf you haven t received Py z your copy of Lindsay s JE Electrical Books catalog you ve really missed something You ll find one of the most bizarre col lections of paperbacks pam phlets industrial references on incredible plans lost secrets forgotten events and strange theories ever assembled CATALOG PACKED WITH UNUSUAL PLANS Write for a catalog Learn how to make neon signs rewind motors get high power from auto alternators and genera tors build a spot welder an electric scooter an arc furnace to melt metal build a storage battery a high perform ance crystal set even a dangerous X Ray machine It s all here Write for your copy today i B Build a genuine working solar cell Turn sunlight into electricity Per vs haps not the highest ef ficiency but low cost jg Really works lt s for amp i real Complete plans Write for 1 CATALOG Write for your copy of Lindsay s new Electrical Books catalog and see for yourself what you ve been miss ing Send 1 00 US amp Canada or 4 00 foreign airmail We ll send your catalog immediately Write today MMWMMW admedeam adiohistor Build SOLAR CELLS Y out the centuries and much more Explore the k k amp KPRESENTING A x amp 4 x kd STARRING dk dk dk dc JERRO
55. 19 95 e XY Operation 2 Axis e TY Sync P 2 100MHz x 10x 23 95 Delayed Triggering Sweep ys Digital LCR Meter ARRY P Digit Multimeter Multimeter tug LC 1801 COMPLETE LINE Dae M 7000 CM 365 58 95 x 125 1 35 65 9 Ranges Measures 05 DC Accuracy L AC DC Voltage amp Amps 1pf 20 000ufd Coils 1uH 200H 1 Resistance Resistance 10 2000MQ 5 bask accy Caps ipt 200u Diode Logic amp Trans test i Zero control Res 01 20M Capacitance 1o 200uF h wilh case Wide Band ind Signal Generators is 65 SG 9000 Kit 45 2 to 15V at JA n l 1 1 29 x i Sed in Ep EE RF Freq 100K 450MHz p or poe a B AM Modulation of 1KHz rovides sine Lrrangie square Vari wave fram Hz io MHz Contains all the desired features for doing experiments alice Features shori circuit protection all supplies True RMS 4 1 2 MULTIMETERS Bes sha k 1 req 21 PE de and n case 23F 85 Function Generator 25F 87 3 E Blox 27F 8050A 73 806CA 75 8062A 77F More CALL FOR SPECIAL PRICING yee Power Supply XP 620 49600 28 95 AM or FM capability Soldering Station Temperature Controlled 7 M 110CF Se UR SL 30 99 m b i 29 95 id i n Ad i en lt i Semiconductor t range qua T0MHz DC or AC eC 300 900 E k Triggered Sweep Grounded tip Finest in the industry brated Verl amp Hor Fis most p Overheat protect 10 rock steady patterns Reads Volts amp Freq digi
56. 5 is a plot ona semi log graph of the values listed above Since the graph is a straight line the log amplifier proto type is reasonably accurate at least for the range of values over which I tested it The output of this log amplifier is not exactly the log of the input voltage In stead the output is approximately 0 06 log V K where K is a constant For the circuit I tried K is 0 495 Different amplifiers will give slightly different val ues of K You can compute the exact val ue with a scientific calculator The output from a log amplifier can be transformed back into linear form by means of an antilogarithmic amplifier Antilog amplifiers can also be used to ex pand a very narrow range of input volt ages into a much wider and therefore more easily resolved voltage range Shown in Fig 6 is the schematic for a basic antilog amplifier you can easily as semble The components are essentially the same as those of the log amplifier in Fig 4 The chief difference is that the feedback circuit in Fig 4 has become the input portion of the circuit in Fig 6 If the input of an ideal antilog ampli fier is connected to the output of an ideal log amplifier the resulting transfer func tionis V au Vin In practice of course both amplifiers contribute various er rors and the output does not exactly fol low theinput In the case of the prototype log and antilog amplifiers I tried the er ror was rather substantial as
57. 5Z temperature transducer IC6 LMC7660 voltage converter IC7 LM2931 fixed 5 volt regulator IC8 79L05 low power fixed 5 volt regulator IC9 LM336 2 5 2 5 volt precision voltage reference LED1 Low power high efficiency red light emitting diode LED2 Low power high efficiency green or yellow light emitting diode Capacitors C1 thru C8 C14 0 1 4F 50 volt cer amic monolithic C9 C10 C12 C13 10 pF 25 volt elec trolytic C11 220 pF 25 volt electrolytic Resistors 4 watt 1 tolerance R1 1 000 ohms R2 150 000 ohms R3 6 980 ohms R5 46 400 ohms R6 R7 R9 10 000 ohms R8 11 300 ohms The output of the temperature compensating circuit is applied via R5 to summing amplifier 7C3 which sums this voltage with the amplified thermopile voltage The output of IC3 goes to a degree circuit made up of S2 IC4 and related components The primary purpose of this degree circuit is to modify the voltage to make it in millivolts correspond to either Celsius or Fahrenheit degrees depending upon the setting of S2 With S2 set to F 50 millivolts yields a meter reading of 50 F Simi larly in the C position 50 millivolts yields a reading of 50 C Switch S2 also controls two light emitting di odes red F LED2 and green C LEDI Calibration for this circuit is ac complished with R 6 and R4 Poten tiometer R4 is used to adjust the gain of the amplified thermopile voltage and R16 provid
58. 80 10Y gearhead motor amp je 40 RPM T 32 RPM with load Operates at lower voltages with reduced speed and torque 6 3 pound inches torque Stall 27 pound inches 3 1 long X 1 375 diameter Shaft 0 187 dia CAT MOTG 14 11 50 each 10 for 100 00 OPTO ISOLATORS S Isolator Off resistance 500 ohms On re sistance 500K ohms 2000 volt isolation Forward voltage 2 Vdc CAT CLM 6000 2 50 each 10 for 22 00 Sigma 301T1 12B1 Signal applied to the input is coupled by means of light to isolated photo conductive cell High reliability switching 12 Vdc CAT OP 301 1 50 OPTO SENSOR mounting ears 1 8 opening 3 4 mounting ears CAT OSU 6 50 each 10 for 4 50 100 for 40 00 CAT SMT 6 6 00 each 10 for 50 00 ORDER TOLL FREE 1 800 826 5432 FAX 818 781 2653 Terms Phone orders must be charged to Visa MasterCard or Discover Minimum order 10 00 CA residents add sales ABLE MATE INC Are You Tired of Paying Outrageous Fees All makes and models of cable equipment shipped within 24 hrs Quantity discounts For free catalog send S A S E to Cable Mate Inc 450 Shag Bark Algonquin IL 60102 C O D orders accepted CALLE FOR PRICES TODAY 800 422 0525 708 658 2121 ER Nolllinois orders Hours 8 00 am 5 00 pm central time eee com 95 5 CAPACITANCE RANGES 30 DAY E LOW BATTERY Warning uh CONTINUITY TEST BUZ2ER bded TRANSIS
59. ALOG CIRCLE NO 78 ON FREE INFORMATION CARD November 1990 MODERN ELECTRONICS 79 FREE CATALOG 1 800 648 7938 JERROLD HAMLIN OAK ETC CABLE TV DESCRAMBLERS Special Dealer Prices Compare our Low Ratail Prices Guaranteed Prices amp Warranties Orders Shipped immediately REPUBLIC CABLE PRODUCTS INC ABD Paradise Rd 15 Dept 802 r ciim Las Vegas NV 89108 For all other information 702 362 9026 REMOTE CONTROL KEYCHAIN Complete w mini transmitter and 5 vdc RF receiver Fully assembled including plans to build your own auto alarm Write for more information Quantity discounts available ilice Mu PUE ays refun ONLY 24 Jo Add 3 shipping VISITECT INC Dept M 415 872 0128 PO BOX 5442 SO SAN FRAN CA 294080 SURVEILLANCE TELEPHONE This i a normal functioning telephone EXCEPT it has a secret built in monitor Only YOU can call and monitor all conversations using a secret code and never be detected Range Unlimited 175 00 month Warranty Phone Tap Catalog 3 00 LISTEN ELECTRONICS 603 Elgin Muskogee OK 74401 1 800 633 TAPS SATELLITE TV SY STEMS UPGRADES PARTS PLUS BOOKS amp TAPES INSTALLATION VIDEO 33 95 ApD 2 S H VIDEO FREE WITH SYSTEMS CaLL WRAITE TODAY 800 334 6455 us ec 218 739 5231 MN SKYVISION INC 2014 COLLEGE WAY FERGUS FALLS MN 56537 tanm UPDATE REPAIR YOURSELF CABLE OESCRAMBLERS OAK M358 COMBO 39 95 Jerrold Zenith Hamli
60. ASS You get your FCC License or money refunded Send for FREE facts now MAIL COUPON TODAY p 21 2 2 2 COMMAND PRODUCTIONS FCC LICENSE TRAINING Dept 206 P O Box 2824 San Francisco CA 94126 Please rush FREE details immediately I I NAME L ADDRESS emon u d CITY STATE ZIP _ Sona E ee ewe ea Jerrold SB w Trimode Ei 7 Super Tri Mode dre AH Oak KN12 w VS Scientific and SA Co Pioneer Hamlin MLD 1200 US Cable will Beat Anyone s Price Advertised in this Magazine Stargate converter Panasonic converter 99 79 30 Days Money Back Guarantee Free 16 page Catalog Visa M C COD or send money order to US Cable TV Inc Dept KME11 4100 N Powerline Rd Suite F 4 Pompano Beach FL 33073 L 800 445 9285 ur Hecord ja the undersigned do declare under penalty of per that al products purchased now and in the future will be ien Cable TV systems with proper authorization from local officials or cable company officials in accordance with all applicable federal and state laws FEDERAL AND VARIOUS STATE LAWS PROVIDE FOR SUBSTANTIAL re aa AND CIVIL PENALTIES FOR UNAUTHORIZED Date Signed No Florida Sales CIRCLE NO 94 ON FREE INFORMATION CARD 64 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com MicroManager chip supervises the pro cessor in a computer system If the pro cessor does not chec
61. All the information is here in one handy concise directory with descriptions technical specifications model num bers retail prices and photographs How do you get a ham license What s the latest on the code free license What equipment do you really need to work the satel lites Should you buy acomputer for your shack How do you add computer control to your rig You can buy with confidence when you have all the facts Order the 1991 Equipment Buyer s Guide today You ll need the Antenna Buyer s Guide to squeeze every last dB out of your antenna dollars Make sure you get the best possible antenna system for the best price HF and VHF UHF directional and omnidirectional verti cal and horizontal mobile and portable they are all cov ered in depth Tuners cables wattmeters and more You ll find detailed charts specification photos and re tail prices Advice on getting the propertower and anten na permits from a leading authority on PRB 1 Step by step guide to putting up your first beam The bands are hotter then ever right now You can t afford to wait ORDER YOUR BUYER S GUIDES TODAY L on t miss the most valuable buying guides in the Amateur Radio Field eS Mc ee M 0 em 9 o M ese Lj EQUIPMENT BUYER S GUIDE YES pleasesend me copiesat 4 95 each 3 ANTENNA BUYER S GUIDE Name Call Addres
62. BLERS Jerrold SB 3 refurbished or as is CONVERTERS Jerrold Models DRX 400 JRX and Hand Remote Control no Canada sales for Descramblers AFFITECH ask Daniel Perreault 514 656 9150 ELECTRONIC SURVEILLANCE ELECTRONIC SURVEILLANCE 40 complete construction plans from America s 1 designer of electronic spy equipment FREE CATALOG Wilson E P O Box 5264 Augusta GA 30906 CABLE EQUIPMENT CABLE TV SECRETS the outlaw publica tion the cable companies tried to ban HBO Movie Channel Showtime Descramblers Converters etc Suppliers list included 9 95 Cable Facts Box 711 ME Pataskala Ohio 43062 MISCELLANEOUS ENGINEERS programmers technicians Sil icon Valley CA needs YOU For free sample of current listing write Excel Services P O Box 36046 San Jose CA 95158 ASIAN LADIES want correspondence for friendship marriage SUNSHINE INTER NATIONAL Dept TW Box 5500 Kailua Kona Hawaii 96745 808 325 7707 DATA ACQUISITION ADAPTERS Plans kits assembled For Information send 3 0 refundable to SCOTTECH 485 Old Ridge Road Webster NY 14580 ATTRACTIVE ORIENTAL LADIES seek ing correspondence marriage Professional introductions since 1984 Asian Experience Box 1214TZ Novato CA 94948 415 897 2742 ou CLASSIFIED ADVERTISING ORDER FORM Mail this form with payment to MODERN ELECTRONICS Classified Dept Hicksville NY 11801 Name Street Address City 76 N
63. BM PC or compatible computer lium arsenide infrared emitting di ode inside optical isolator C The infrared energy emitted at this point triggers on the bidirectional DIAC also inside C When the DIAC switches on it triggers triac Q7 into conduction In turn Q7 completes the 117 volt ac line circuit to any load plugged into receptacle SO which now turns on Resistor RJ limits current flow through the LED inside C while resistor R2 limits gate current to Q If you substitute a different triac for Q1 check maximum forward current and gate current ratings to ensure a safe forward current flow Use Ohm s Law to determine the value of gate resistor in such a case As shown in Fig 1 the project is expandable to include up to eight control channels Select for each channel a triac that will safely accom modate the expected load Note that the project connects to your computer via the latter s paral lel port If you are using a parallel printer with your computer you must install a second parallel port and configure the operating system Say You Saw It In Modern Electronics to recognize it Alternatively you can use an external AB switch to se lect between printer and AC Inter face or use a duplex connector into which both printer and project can be plugged to use the single port If you go the last route turn off your print er when operating the AC Interface Otherwise signals from the printer can upset
64. Broadway State 1 Zip Check category you wish to be listed under or note a special heading 6 additional you want Audio Communications Miscellaneous Computers Special Heading _ Electronics Video PRINT EACH WORD SEPARATELY 1 00 per word 15 word minimum Note that P O Box numbers and telephone numbers must be counted as two words each Circle additional words ycu wish boldfaced at 20 more each initial boldface word is free Free Boldface 2 3 4 5 6 7 8 9 10 li 12 13 14 15 15 16 16 PLEASE ADD Extra Bold Words 20 cents Special Heading 6 Payment may also be made by MasterCard or Visa For this please fill in information below Credit Card Number Print Full Name Expire Date Signature 80 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Say You Saw It In Modern Electronics NEW PRODUCTS from page I7 Soldering System Anelectronic soldering system that is said to offer high capacity perform ance in a compact easy to handle micro iron has been introduced by Ungar The Model 9910HC iron fea tures a new thermal thrust patent ed tip design that reportedly delivers 4099 greater thermal capacity than competitive models that use standard soldering tips Among other performance fea tures the new iron provides a closed loop circuit that assures temperature stability at idle
65. CATIONS Address 2i FE x AND SS s qus i i puta State es M Zip eee Phone mm am a Gaivits GEAT 3219 27 95 Counts as 2 SUN MED Signature zd 2898P 15 95 2831P 515 95 Valid for new members only Foreign applicants will receive special ordering instructions Canada must remit 1990 ELECTRONICS BOOK CLUB in U S currency This order subject to acceptance by the Electronics Book Club MDNE1190 All books are hardcover unless number Blue Ridge Summit PA 17294 0810 iu mei Rae Me aei Ae ng uk ca ees e ed is followed by a P for paperback A wiw americanradiohistorv com THE MAGAZINE FOR ELECTRONICS amp COMPUTER ENTHUSIASTS NOVEMBER 1990 18 24 32 37 44 48 57 62 65 68 eS GN 10 72 82 VOLUME 7 NUMBER 11 FEATURES Thermally Machine Project Boxes Give a professional look appearance to plastic enclosures that house projects By Adolph A Mangieri An Infrared Thermometer Accessory Lets any DMM measure tempera ures Fast without requiring physical contact By Thomas R Fox A Precision DC Power Supply Laboratory grade low voltage supply offers two user selectable voltage ranges short circuit protection and ability to go down to 0 volt By Dennis Eichenberg Stereo Audio Test Box Simplifies connection of test equipment to audio gear for troubleshooting and repair By Irving E Farnham Computer Controlled AC Interface In
66. CTRONICS November 1990 WWW americanradiohistorv com Say You Saw It In Modern Electronics and turn the print spooler off a simple task However when we tried to print a simple document with Windows Write we could not do it When we called the technical support tine at Metro we found out that versions of Windows prior to 3 0 work just fine with LaserTwin since earlier versions use the BIOS Windows 3 0 doesn t Thus you must do one of the following config ure you printer port as LPT1 OS2 using the Windows Control Panel or edit the Windows WIN INI file by adding the line LPTI PRN to the Ports section of the file Once we made the change the printer worked fine When we tried to do some fancy print ing with Aldus PageMaker 3 0 we quick ly realized that LaserTwin includes just Courier and line printer fonts The only way you can use other fonts is if you have additional soft fonts Luckily Metro Software also sent us its SuperFonts 25 1 program see below we didn t have any other soft fonts available For anyone who desires more control of the printer LaserT win includes a text formatting and printer control language The language includes commands for font control special effects and box graphics among other things To use the commands you place them in text des tined for the printer The text can come from a word processor spreadsheet database or language program For ex ample to print a
67. ETIKITS from KINETICO electronic kits outputting light or sound Free catalog KINETICO P O Box 1634 NY NY 10114 0508 MINIATURE FM TRANSMITTERS Track ing Transmitters Voice Disguisers Bug De tectors Phone Devices More Available in kits or assembled and tested Catalog 2 00 XANDI ELECTRONICS Box 25647 B5 Tempe AZ 85285 5647 SURVEILLANCE COUNTERSURVEIL LANCE devices catalog Cameras bug detec tors video camera detectors transmitters communications and much more Catalog 3 00 DSP P O Box 1275 ME Redondo Beach CA 90278 STRANGE STUFF Get the advantage Laser listener surveillance descrambling under ground information Plans kits complete items Informational package 3 00 refund able DIRIJO BOND Box 212 Lowell NC 28098 REMOVE LEAD VOCALS from standard stereo records CD s tapes FM broadcasts so YOU can be the lead singer of your favorite band Detailed plans 6 95 PC Board and Parts also available WEEDER TECHNOL OGIES Dept E 14773 Lindsey Mt Orab Ohio 45154 LASERS Imw to 2kw worlds largest selec tion of new and used surplus FREE CATA LOG MWK Industries 1269 Pomona Rd Corona CA 714 278 0563 SURVEILLANCE Countersurveillance Equip ment Catalog 5 00 Eavesdropping Detection Equipment P O Box 1087 Williamsville NY 14231 SURVEILLANCE COUNTERSURVEIL LANCE Guaranteed lowest prices Unbeliev able Detectors Jammers Transmitters Phone Secu
68. IF BIT3 0 THEN GOTO 390 It BETA HEN GOTO 390 IF BITS THEN GOTO 390 IF BIT6 0 THEN GOTO 390 IF BIT D THEN BYTES z BYTES 240 300 360 THE 0 BI COPYRIGHT GEORGE F STOCKMAN IV 1989 ILE DELAY gt TIMER WEND STRINGS 41 32 BIT NUMBER TO TOGGLE CR TO RESET ESC T mY THEN 159 ELSE IF A 1 THEN 260 ELSE IF AS 27 THEN ELSE IF AS 4 THEN 320 ELSE IF A 5 THEN ELSE IF AS 7 THEN 380 N 230 0 0 0 0 o T1 0 BIT2 0 BIT3 O 0 BIT6 0 BIT7 0 GOTO 430 THEN BITO BIT1 BIT2 BED BIT4 BITS BIT6 BIT7 B CLS SYSTEM ELSE BEEP SGOTO I59 1 DEC DEC 1 ELSE BITO 0 DEC DEC 1 DEC DEC 2 ELSE BDTI DEC DEC DEC DEC a 4 ELSE BEI DEC DEC DEC DEC 8 ELSE BETS DEC DEC DEC DEC 16 ELSE BIT4 Q4 DEC DEC lt DEC DEC 32 ELSE BIT5 0 DEC BEC Az DEC DEC 64 ELSE BEIT5 0 DEC DEG 1 DEC DEC 128 ELSE BIT7 0 DEC DEC YTES STRS BIT7 STRS BIT6 BYTES BYTES STRS BIT5 STRS BIT4 BYTES BYTES STRS BIT3 STRS BIT2 BYTES BYTES STRS BIT1 STRS BITO DEC LOCATE 14 28 PRINT BYTES GOTO 150 42 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com ac line potential appears in parts of the circuit Incorrect wiring can prove disastrous to delicate compo nents So make certain that your wir ing 1s correct Once you are Satisfied with your wiring temporarily set a
69. ION DEVICE onte 10 00 De COCO LLL Se SS Se SS 3 MILE FM VOICE TRANSMITTER 34 50 HAND CONTROLLED PLASMA FIRE SABER 49 50 HI FLUX NEGATIVE ION GENERATOR 34 50 PLASMA LIGHTNING GLOBE 49 50 VISIBLE SIMULATED 3 COLOR LASER 44 50 PROGRAM AVAILABLE xo an 3 ASSISTANCE HOMING TRACKING BEEPER TRANSMITTER 44 50 2 5 MW HAND HELD VISIBLE LASER GUN 249 50 BTC3K 250 000 VOLT TABLE TOP TESLA COIL 249 50 eo 0G2K ION RAY GUN project energy without wires 129 95 TKEIK TELEKNETIC ENHANCER ELECTRIC MAN 79 50 we VWPMTK 3 MILE AUTO TELEPHONE TRANSMITTER 49 50 LIST10 IPG7D ITM10 TAT30 PSP40 DNE10 LGU20 BLS10 ASSEMBLED ASSEMBLED IN OUR LABS INFINITY XMTR Listen in via phone lines INVIS PAIN FIELD BLAST WAVE GEN en 100 000 VOLT INTIMIDATOR UP TO 20 AUTO TELEPHONE RECORDING DEVICE PHASOR SONIC BLAST WAVE PISTOL 89 ALL NEW 26 VIVID COLORED NEON STICK 74 50 5 TO 1MW VIS RED HeNe LASER GUN 199 50 100 000 WATT BLASTER DEFENSE WAND 89 50 EASY ORDERING PROCEDURE TOLL FREE 1 800 221 1705 or 24 HRS ON 1 603 673 4730 or FAX IT TO 1 603 672 5406 VISA MC CHECK MO IN US FUNDS INCLUDE 10 SHIPPING ORDERS 100 00 amp UP ONLY ADD 10 00 CATALOG 1 00 OR FREE WITH ORDER INFORMATION UNLIMITED P O Box 715 DEPT MES AMHERST NH 03031 November 1990 MODERN ELECTRONICS 75 Area Code Speed Dialer from page 47 separate l
70. L plotter output Acquisition modes provided in clude normal average envelope and roll Triggering can be set for peak to peak normal TV V TV H or single Frequency is measured auto matically by all models while P P Continued on page 14 10 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Say You S w It In Modern Electronics How to build a high paying career even a business of your own in computer programming a eww LII M J z RICK BRUSH NRI PROGRAMMER ANALYST Start with training that gives you hands on programming experience at home and at your own pace Training that begins with BASIC then continues with Pascal C and COBOL today s hottest computer languages Training that even includes a powerful IBM compatible computer modem and program ming software you keep Start with real world training The kind of training only NRI provides Now with NRI s new at home training in Computer Programming you can be one of today s highly paid creative team of computer wizards who give computers the power to carry out an astonishing range of business profes sional and personal applications Now with NRI you can be a computer A programmer ready to build a high paying career even a business of your own making computers do anything you want them to do The only programming course that includes a powerful computer system and software you keep Unli
71. LD HAMLIN OAK AND OTHER FAMOUS MANUFACTURERS FINEST WARRANTY PROGRAM AVAILABLE LOWEST RETAIL WHOLESALE PRICES IN U S ORDERS SHIPPED FROM STOCK WITHIN 24 HOURS FOR FREE CATALOG ONLY 1 800 345 8927 FOR ALL INFORMATION 1 818 709 9937 m PACIFIC CABLE CO INC cy 7425 RESEDA BLVD DEPT 1204 RESEDA CA 91335 Discover the finest collection of quality Tesla books available including both new books and reprints of very old rare publi cations Discover a new booklet on Tesla s lost inventions a 1904 book on Tesla s experiments with wireless power trans mission rare and unusual books on the construction and use of high voltage Tesla coils and much more Highest quality guaranteed Build Lightning Bolt Generators Build a Wimshurst machine Telsa Coil Oudin Coil Induc tion Coil Winter static electric ma chine More Build Jacob s Ladder con densing electro g scopes Leyden jars scintillating tubes electri cal cannons Cavallo s cyl inder machine and much more Great science proj ects Most complete collec tion of high voltage b books youll find any where RARE EARLY RADIO BOOKS Incredible collection of Org Carly shortwave radio E books disc television unusual radio experiments and more You ll even discover a strange collection of books on Fringe Science lost continents perpetual motion unusual phenomena recorded through iN
72. ON FREE INFORMATION CARD Bi BOOKS I i Troubleshooting and Repairing Cam corders By Homer L Davidson Pub lished by Tab Books Soft cover 533 pages 22 95 The electrical and mechanical com plexity of the camcorder demands an au thoritative reference one can turn to when troubleshooting and repairing these sophisticated video devices is re quired In a general sense this book fits the bill The stated aim of this book is to provide practical and technical data to help make camcorder repairs much easi er Examining the contents this aim ap pears to be admirably achieved Beginning from square one the book s opening chapter is devoted to the cam corder in general and videocassette for mats Here it discusses Beta VHS and VHS C and 8 millimeter formats and goes on the discuss camcorder features in general hookups etc A second chapter titled Tips and Techniques introduces service precautions service data voltage measurements signal paths test equip ment and more Following chapters dissect the cam corder dividing it into the Camera Sec tion Video Circuits System Control Trouble Detection and Servo Circuits Motor Circuits and Audio Circuits Each chapter deals with the title topic in some detail to help familiarize the reader with the various elements that make up thetypical camcorder and how they form the whole Still later chapters deal with mechani cal tape operations mechanical and elec t
73. R A NC a ee E Fig 2 Cookie cutters include large round and square hole makers made from shells of battery cases and miniature r f transformer shields brass or stainless steel cups For round cutters use the bottom por tion of stainless steel cases from AAA and AA alkaline or nickel cad mium cells Use caution when cutting these cells because the contents are caustic Thoroughly clean the cutters and square up the open ends Bevel sharpen round cutters inside to a knife edge using a cone shaped mounted stone by hand Drill a cen tral hole in the bottom of the cutters to pass a 6 32 machine screw For the Weller Model SP40 iron cut a 1 inch long by inch diameter shaft For other irons slide the shaft stock fully inside the iron then withdraw it 4 inch and mark and cut it to length Square up one end and drill and tap axially for a 6 32 machine screw Se cure the cutter to the shaft with a 6 32 x inch screw and lockwasher In use the cookie cutters replace the soldering iron tip with cutter butted against the barrel of the iron to take up punching forces These cutters can also be retained by the shaft extender to permit ready inter changability of all cutters In this case and especially for the larger cookie cutters install slide on spacer bushings as shown on the round cut ters in Fig 2 The bushings increase heat flow and impart rigidity 20 MODERN ELECTRONICS November 1990 WWW americanradiohi
74. R5 thru R9 100 000 ohms see text for quantity R4 R10 1 megohm R11 100 000 ohm watt pc mount trimmer potentiometer Miscellaneous B1 9 volt alkaline battery see text S1 Spst normally open momentary action pushbutton switch Printed circuit board or perforated board with holes on 0 1 centers and suitable Wire Wrap or soldering hardware DIP IC sockets 1N914 isolation diodes see text 9 volt dc plug in wall type power supply op tional see text suitable enclosure optional see text light emitting diode and 470 ohm watt resistor for test purposes see text terminal strip optional see text machine hardware hookup wire solder etc the instrument If you are planning to build more than one Speed Dialer for different area codes consider housing them in a separate enclosure and powering them from the ac line via a plug in wall type 9 volt dc power supply As can be seen in Fig 2 the com ponents that make up the project eas ily fitona small 4 5 x 7 cm IC type prototyping board such as the Radio Shack Cat No 276 150 Alternative ly you can design and fabricate a printed circuit board on which to mount the components Whichever way you go though be sure to use sockets for the two ICs You can use any power MOSFET for QJ The IRF 511 specified in the Parts List is overkill but it is readily available from your local Radio Shack store To save space the heat sink tab can b
75. RI For all the details about NRI s at home training in Computer Programming send the coupon today Soon you ll receive NRI s fascinating information packed full color catalog Open it up and you ll find vivid descriptions of every aspect of your NRI training You ll see the computer system included in your course up close in a special poster sized foldout section nd best of all you ll find out how your NRI training will make it easy for you to build that high paying career even a business of your own in computer programming You master today s hottest computer languages galning the skills you need to bulid programs for a wide varlety of real world applications With your personal NRI instructor on call and ready to help you use your computer and software to actually design code run debug and document programs in BASIC Pascal Send for your NRI catalog today It s yours free If the coupon is missing write to us at the NRI School of Computer Program ming McGraw Hill Continuing Educa tion Center 4401 Connecticut venue NW Washington DC 20008 IBM is a Registered Trademark of the IBM Corporation Afr School of Computer Programming McGraw Hill Continuing Education Center W 4401 Connecticut venue NW s Washington DC 20008 z YES Please rush me my FREE catalog describing NRI s at home training in Computer Programming A m NAME please print ADDRESS CITY
76. RONICS 51 MMWMuweamercanradiohbistorv com 10 000 E a zz NONONDK NINDCNDNONNL TTT ELLE NININONT SERN REN NIRS TE ELE WJ tc x Us 1 000 N z tc 2 Ie fo ff E 00 je paar f AAN BF Z3 Er ei FAI d PAP y YT lo 1 0 001 0 01 MI s a wy ALATA Ipod a eA Nu le es a a AO a K TN RE X NRN Na T Hee A e a oH 0 1 1 0 BCBBIN AREA SQ IN Fig 5 Bobbin capacity in number of turns and various wire sizes nomograph This expression simply reflects the step up or step down voltage ratio of the transformer For circuits that op erate at low output voltages the di ode drop of the bridge rectifiers 1 4 volts for a full wave bridge must be considered when calculating trans former turns ratio necessitatirg a greater number of secondary turns The feedback winding of the trans former must provide sufficient posi tive feedback to the transistor oscilla tor circuit to sustain oscillation Since the base circuit of each transis tor can be forward biased with a source potential of about 1 4 volts the number of turns for this winding will be relatively few For most de signs a 10 turn center tapped feed back winding will work very well Wire size for this winding is not criti cal and can be any convenient size e Winding the Primary The dc to dc converter transformer operates with square waveforms that have fairly rapid rise and fall times When cur rent in an ind
77. TOR CHECKER GUARANTEE 3 20 mHz FREQ COUNTER ee aao KELVIN Electronics zi 7 Fairchild Ave Plainview NY 11803 516 349 7620 1 800 645 9212 FAX 516 349 7830 CABLE TV BOXES Descramblers Converters FREE CATALOG TRANS WORLD CABLE CO 12062 Southwest 117th Ct Suite 126 Miami Florida 33186 800 442 9333 INSTRUMENT ENCLOSURES Molded ABS instrument enclosures Matching 4 front and rear paneis oS A Integrated PC board E standotis and two sets of vertical mounting slots for front and rear sub panel PC boards All enclosures are 6 wide X 6 1 4 deep Available in black ivory blue and beige Specify color FRONT amp REAR PANEL HEIGHT 2 1 4 CAT MB A 7 50 each 10 tor 65 00 2 5 8 CAT MB B 7 75 each 10 tor 67 50 3 CAT MBC 800each 10 tor 70 00 PHOTOFLASH CAP Rubicon CE 210 MFD 330 V 0 79 dia X 1 1 high New 1 prepped with 1 4 black and red wire leads soldered to the terminals CAT PPC 210 2 50 each 10 for 22 50 100 for 200 00 STEPPING MOTOR Airpax C82711 M1 17 Vde 23 25 ohm dual coil P M motor 7 5 degrees per step 2 25 dia X 91 thick 0 25 dia shaft 6 wire leads tl tax 48 Continental States Add 3 50 for shipping handling Ali Others Including AK and HI pay full shipping Quantities limited No C O D CALL TOLL FREE FOR A FREE 60 PAGE CAT
78. TORS Electronics and You VT 208 VCR MAINTENANCE amp REPAIR VT 203 54 mins cies 32 95 INTRODUCTION TO VCR REPAIR VTS204 110 Mino co eor Sen e 59 95 Electronics and You VT 205 PART 4 POWER SUPPLY VW een m mail check or money order to E UCANDO VIDEOS AC P O BOX 928 GREENVILLE OH 45331 CIRCLE NO 95 ON FREE INFORMATION CARD November 1990 MODERN ELECTRONICS 69 Put Professional Knowledge and a COLLEGE DEGREE SOFTWARE FOCUS in your Technical Career through 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 abso 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
79. Thermoplastics may include fillers such as waxes to add flexibility and fibers to impart strength or better machinability When heated this type of plastic gradually softens at first and eventually melts and finally burns with increasing temperature emitting acrid and toxic fumes Ther moplastics machine reasonably well provided you have a drill press and operate it very slow using an assort ment of brad or spur point bits Thermosetting plastics such as the phenolics make up the second cate gory of plastics Thermosetting plas ticis formed by chemical reaction be tween phenol and formaldehyde it does not soften when heated but does eventually char at sufficiently high temperatures Thermosetting plas Say You Saw It In Modern Electronics 2 EE SS Ne EGEEEEULURE CEGA URANNLLECEOILTCLCOULAELNCIE EATER HSHMSNSOMLEQEECAAGIREEELELLLLLOULL L U AEE 8808080808088 MMER EE OAU A 1 AO OL OOx LLQGLSLAAAK ECEEPYCII SEEEURAOE PP LLL o Euer E p E oa preis Uh qe H zo a a muB um mr ICE Fig 1 Small hole cutters include thermal punches made from TV rabbit ears antenna sections and round rectangular and knife shapes Clean out tool is shown at bottom tics are used where high strength di mensional stability and resistance to high temperature are required With excellent electrical properties the plastic is widely used for switch board panels relay frames motor switch parts and the plast
80. Your Catalog Today E Consumer Electronics Military Electronics Ei Personal Training From A Renowned Faculty Unlike the impersonai 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 you answer your questions and provide technical assis tance when you need it Cowes Ara WETS on y e Ch CIE World Headquarters i Cleveland Institute of Electronics Inc 1776 East 17th St Cleveland Ohio 44114 C1 YES Please send me your independent study catalog For your convenience CIE will have a representative contact you there is no obligation Print Name qu me Ades snai mmal mem m m xs i City State Zip 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0000000000000 0 0 Age Area Code Phone No Check box for G I Bill bulletin on educational benefits Veteran Active Duty L a Mail This Coupon Today 45 PN OFF VOICE TIMER DIM p u CLOCKt OFF CLOCK2 ise use cw ey off TIME LU TIME SET boi a 7 C E Dou mM Scan the world bands with Kenwood s R 5000 R 2000 and RZ 1 Listen in on foreign music news and commentary i Monitor local police fire and other public P safety services as well as the Marine channels and the many other services
81. ability Options C R7000 RC 12 remote control EX 310 voice synthesizer CK 70 DC adapter MB 12 mobile bracket IC R71A RC 11 remote control EX 310 voice synthesizer CK 70 DC adapter MB 12 mobile bracket FL 32A 500Hz FL 63A 250Hz and FL 444A filters See these quality ICOM receivers at your local authorized ICOM dealer today Specifications of the IC R7000 guaranteed from 25 1000MH72 and 1260 L390M H7 No coverage from 1000 1025M Hz ICOM America Inc 2380 116th Ave N E Bellevue WA 98604 Customer Service Hotline 206 454 7619 3150 Premier Drive Suite 126 Irving TX 75063 1777 Phoenix Parkway Suite 201 Atlanta GA 30349 ICOM CANADA A Division of ICOM America Inc 3071 5 Road Unit 9 Richmond B C V6X 274 Canada All stated specifications are subject fo Change without nonce or obligation Al EOM racos signihicantly exceed FCC regulations limiting spurious emissions Receiwers9 B O ICOM First in Communications S t amp S ER Lr SELECT 5 BOOKS uem Ly Gordes SMcComb 3260 22 95 a ELECTRONIC p oon me teres d THE COMPLETE BOOK OF cae 2960 27 95 OSCILLOSCOPE ES po Qo Counts as 2 E ES m ome url 1625P 22 95 sezona Counts as 2 TIPS amp TECHNIQUES FOR ELECTRONICS EXPERIMENTERS 18 HICH E TEL rapes at Course A T omal o ali types and VPE pond press gr ste PRESTISS f 2826P 16 95
82. an French Italian Spanish Portuguese Cyrillic Russian Pho netic Russian Phonetic Japanese Phonetic alohabets and eight lan guage dictionary included in this rugged spiral Dound manual a MUST forany serious DXer or Contestor Beat the competition Order yours to day Only 10 00 plus 2 00 per order shipping Supplements available in less used languages Dutch Flemish Danish Finnish Swedish Serbocratian 4 00 per supplement Be sure to state which language supplement you need New cassette tapes in eight languages Now you can hear the exact pronunciation of the sentences phrases and words covered in The Radio Amateur s Conversation Guide Each high quality language tape is recorded with proper dialect and usage in one of the languages in the Conversation Guide a A ea o _e ADO BOOKSTORE GREENVILLE NH 03048 Now a division of CQ Communications Inc Please send the following Conversation Guide Book 10 Language Tapes 10each Supplements 4 each German Portuguese O Dutch Flemish C French O Russian JDanish Spanish Japanese O Finnish C Finnish O Swedish Serbocroation LJ Swedish Add 2 for postage and handling in North America Total pm Name Address City State ip O Check O Money Order LJ MasterCard VISA Amex Card No Expires wwwW americanradiohistorv com Discover Your Gareer Potential In The Fas
83. an as sume an operating flux density of half that value or 2 000 Gauss Effective magnetic area is deter mined by the physical size and design of the pot core and is specified in square centimeters Use Table 2 to determine the effective magnetic area for various pot core standard sizes The Winding Area listed in the Table Is specified in square inches and will Table 2 Core Magnetic amp Winding Areas Core Magnetic Area Winding Area mm sq cm sq in 7 x 0 041 9 x5 0 11 11 x3 0 16 14 x 8 0 25 18 x 11 0 43 22 x 13 0 63 26 x 16 0 94 30 x 19 1 36 36 x 22 2 01 42 x 29 2 66 0 0038 0 0047 0 0079 0 0153 0 0265 0 0453 0 0653 0 0840 0 1170 0 2150 be used later when determining the capacity of the corein terms of num ber of turns of wire The formula to use to calculate the number of turns is Ny 25 x 109 E CAYBY F where N is the number of turns of one section of the primary is dc supply voltage A is effective magnetic area in square cen timeters B is flux density in Gauss and F is frequency in Hz Only half the primary winding is considered in this equation because each half is subjected to the total power source voltage as previously discussed Once the number of turns of the primary Ny is known the number of turns for the secondary winding N can be easily calculated by the simple relationship N N out put voltage input voltage November 1990 MODERN ELECT
84. application is selected by locating the point where the input power level of the converter and the oscillation frequency meet Follow ing this point down to the horizontal axis the core size is determined Bear in mind that a larger core size than recommended can be used but not a smaller one In some cases you may want to reduce the turns required for your inductor or transformer or pro vide sufficient winding space for one that requires many turns Selecting Wire Size For many ap plications the choice of wire size for the windings will be determined by physical considerations and not by the actual primary or secondary transformer current Very fine wire is difficult to handle However it is important that a tabulation like that shown in Table I be consulted to veri fy that the minimum wire size re quirement is met The current carry ing capacity indicated in Table 1 is based on the acceptable standard of 500 circular mils ampere of current It is important to note that the de sign of the circuit is such that only half of the primary winding carries 50 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com current at any given time Thus the current carrying capacity of the wire selected for the primary winding need be only half the calculated input current of the circuit The resistance of the wire selected for the windings should be taken into consideration when selecting wire size When many tur
85. apter Incredible Flexibility Full Coverage Maximum Performance The superb IC R71A is your key to world wide SSB CW RTTY AM and FM optional communications plus foreign broadcasts in the 100kHz to 30MHz range t features IF Notch low noise mixer circuits and a 100db dynamic range The pacesetting IC R7000 receives today s hot areas of interest including aircraft marine public services amateur and satellite transmissions in the 25MHz SOUELCH 1 U EXPECT THE WORLD OM ICOM RECE to 2000MHz range It includes all mode operation low noise circuits plus out standing sensitivity and selectivity T he IC R71A R7000 combination 1s your window to the world LEN BH Hrki 2 m gt The IC R71A is a shortwave listener s delight ts 32 tunable memories store frequency and mode information and they are single button reprogrammable independent of VFO A or VFO B s operations Dual width an adjustable noise blanker panel selectable RF preamp and selectable AGC combined with four scan modes and all mode squelch further enhance the IC R71A HF reception The IC R7000 features 99 tunable memories and six scanning modes t even scans a band and loads memories 80 to 99 with active frequencies without WWW americanradiohistorv com uM rtr TSikhHz y 12 5 operator assistance Additional features include selectable scan speed pause delays wide narrow FM reception and high frequency st
86. ch a thick ness requires more heat and time to penetrate the plastic Filled plastics such as ABS TV cabinets punched satisfactorily Acrylic and styrene plastics tended to foul tips After several hours of use remove the shaft extender from the iron and clean both to prevent buildup of ox ides and seizing From time to time remove the shaft collars from the tips and the tips from the adapters and clean them with fine steel wool Variations The following may prove to be helpfulif you experiment with larger or smaller wattage soldering irons or cutter tips that are different sizes and n 22 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Say You Saw It In Modern Electronics lengths For a given power input to the soldering iron the heat available to soften the plastic is primarily limit ed by the effective thermal conduc tivity of the relatively thin walls of the cutters Halving tip length dou bles the heat flow Stainless steel cut ters are relatively short because this material is a poor conductor of heat The tips shown in Fig 1 can be adapted to a soldering iron that ac commodates inch screw in tips After you identify the threads on the original soldering tip probably me tric you will need a screw tap that matches the threads of the soldering tip and corresponding machine screws Drill and tap the upper end of the collets or adapters to accept the machine screw Install th
87. ck all your wiring against Fig 1 Do not proceed until you have corrected the problem When using the Stereo Audio Test Box connect the speaker outputs of the amplifier under test to AMPLIFI ER INPUT binding posts BP3 and BP4 in each channel making sure you ob er NH Lodi i d mnia Fig 2 Interior view shows amplifier and speaker connectors mounted on rear enclosure panel right test equipment connectors and switches mounted on front panel left and high power loading resistors mounted on floor center serve the same polarity for each channel Then feed the output froma signal generator into the AUX inputs of the amplifier Connect the input cables of a dual trace oscilloscope to any pair of out puts in each channel and a multime ter set to the ac volts function or any other monitoring instrument to the other pair of outputs in each channel Finally connect speaker systems to the project via the Speaker Output binding posts in each channel Turn on your test instruments and the amplifier Conduct whatever EM Amo by METER RMS j NT T Z1 e A We 7 Say You Saw It In Modern Electronics OUTPUT RIGHT Pw ae P L i f L A F 5 NT LIH SCOPE PEAK TO PEAK d E a FN wi on front panel B of enclosure AMP INLEFT rear panel A Amplifier tests you plan on making One word of caution Never set the switches to UNLOAD without first con
88. d be used E ad ee i ASA ee AEH iE i Ai can Se Se eee a EE Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 53 eV americanradiohistorv com 10 When winding the transform er best construction is obtained by winding the primary using the bifilar technique to achieve maximum cou pling between the primary halves It is mandatory that the winding pro cedure be followed exactly to ensure proper phasing of the primary and feedback windings Start with the feedback winding that is identified by terminals 1 2 and 3 using a length of No 28 mag net wire Place a tag with the numeral on one end of the wire allow about 2 inches of lead length and wind five turns around the bobbin starting with the labeled end At the fifth turn bringthe wire out of the bobbin for a length of about 2 inches Fold the wire back toward the bobbin to form a loop and wind 5 more turns onto the bobbin in the same direction as before Leaving about 2 inches of lead length cut the wire at the ter minal end Secure the winding with one layer of thin insulating tape M y lar tape is good Label the looped center tap with the numeral 2 ard the remaining wire with the numeral 3 Now wind onto the bobbin the bi filar primary Start with two No 28 wires of sufficient length to wind 10 turns for each wire Label the end of one wire with the numeral 4 and the Order Back Issues of end of the other wire with the numer al 5
89. d on perforated board is shown in Fig 2 Select an enclosure that is large enough to accommodate the circuit board assembly and all other compo nents and has suitable front panel space on which to mount the meter movemenis POWER and RANGE switches and POWER LED and the two OUTPUT five way binding posts or banana jacks A suitable enclosure is shown in the lead photo Say You Saw It In Modern Electronics Machine the enclosure as needed This includes cutting suitable size shape holes for the meter movements in the front panel and an entry hole for the ac line cord through the rear panel When you are done with the machining operation holes and cutouts made in metal pan els to remove sharp edges Place a rubber grommet in the hole for the ac line cord If you wish paint the prepared front panel with one or two coats of white or light gray spray enamel Al low each coat to thoroughly dry be fore applying the next and proceed ing to lettering the legends Use a dry transfer lettering kit to label the switch positions the OUTPUT LEVEL control and both meter movements Protect the legends with two or more light coats of clear acrylic spray Al low each coat to dry before spraying on the next Fabricate a heat sink for O froma 2 X 3 inch sheet of aluminum stock Power transistor Q7 comes in a TO 9 package It must be installed on its heat sink with the aid of a TO 3 mounting kit so that it is electrically insulated fr
90. dards and adjust R4 and R16 so that the ther mometer adapter meter arrange ment shows the correct temperatures Calibration for the Celsius mode is done by adjusting R20 After final calibration in Fahrenheit mode set S2 to C The green LED should now light When it does adjust R20 fora correct reading in degrees Celsius in the meter display To convert degrees Fahrenheit to degrees Celsius sub tract 32 and divide the result by 1 8 For example 77 F 77 32 1 8 25 G Using the Project The Infrared Thermometer Acces sory has two main advantages over standard contact thermometers nearly instant response and the abili ty to take temperature measurements without physical contact Useable measurement distance varies from 4 inch just far enough from an object to avoid contact to theoretically in finity assuming the temperature of an infinite size object is being mea sured However for accurate mea surement the field of view of the de tector must be filled as in Fig 7 Note in Fig 7 that the maximum measurement distance depends upon the size of the object With the geom etry shown the minimum size of the object that can be accurately mea sured is about inch in diameter For an object the size of a hand maxi mum measurement range extends to about three inches the temperature Of a car can be taken at six feet and the average surface temperature of an ocean can betaken from space 100 miles a
91. de area networks FECOS supports DOS applica tionsthat are DESQview compatible It communicates with the applica tions via a standard PC AT COM port Information received or trans mitted by DOS applications can be routed to FEALARM SERMON us ing one or two channels of the FECOS multi port card The easy to use software is menu driven and includes pop down windows It lets you control position size and color of all applications windows Platform requirements 80386 processor running at 20 MHz or greater 1M of conventional memory plus a minimum of 3M of extended memory for the four application ver sion of FECOS 7M of extended memory for eight application ver sion EGA or VGA with EGA emu lation capability graphics Microsoft or compatible mouse MS DOS 3 3x and a parallel port configured as ILPTI oOrLEPI2 CIRCLE NO 65 ON FREE INFORMATION CARD EARN YOUR B S E E DEGREE THROUGH HOME STUDY Our New and Highly Effective Advanced Place ment Program for experienced Electronic Tech nicians grants credit for previous Schooling and Professional Experience and can greatly re duce the time 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 Rapidl
92. draped ab domen is presented Palpating the abdo men is accomplished by using the mouse to position the cursor arrow over the area you wish to examine and clicking the mouse button The patient responds with either an expression of pain or acomment about how it doesn t hurt there Results of your examination will dic tate whether further tests should be run medication administered or the patient put under observation You gain the judgment to make these calls from your medical education read ing the 22 page excerpt from a ficti tious Anatomy and the Surgical Tech nique textbook or like me by watching hundreds of reruns of Medical Center and Marcus Welby If you choose the wrong course of action it s off to class for alecture on why you where wrong and what you should have done Having a few patients die on you because of careless ness also tends to hone diagnostic skills In your highly condensed stint as a resi dent you get to treat a variety of illnesses most based in the abdominal area such as infection gas gallstones and kidney stones which are referred to a specialist and appendicitis where you get to operate Performing an operation is quite an ex perience First you visit the Doctor s Lounge to pick out your assistants The nurse there hands you dossiers with the person s picture qualifications strengths and weaknesses and which of the other available assis
93. e s sm Ja u C2 can be used if you need extra dig its Usea separate transistor for each extra digit and observe the proper con nection sequence during programming Activation of the Speed Dialer is accomplished by pressing and releas ing momentary contact switch S This causes C7 to charge and sends QI into conduction In turn Q7 sup plies power from the 9 volt bus to the rest of the circuit With power applied C7 generates square waves that are delivered to the CLOCK input of C2 at pin 14 As the pulses are processed by C2 Q3 through Q7 turn on and off sequen tially closing the row and column R1 R3 10K 10K Q1 IRF511 switches and generating the tones re quired to dial the area code and any other digits At the tenth pulse C2 biases on Q2 causing C7 to discharge and automatically shut off the Dialer Because only low power CMOS chips are used in this project the cur rent drain on the power source is on the order of only 0 5 milliampere Therefore it is practical to use an or dinary 9 volt alkaline battery as the power source for this project Construction Before you build your Area Code Speed Dialer open the telephone in TCM5087 or P5087 pis O2 4 O3 7 O4 10 O5 1 O6 5 Q7 6 O8 9 O9 11 strument with which you plan to use it and
94. e been designed into a product from the start PageMaker Word for Windows and Excel are all examples of products whose pull down menu structure compli ments rather than detracts from the op eration of the program And even these packages offer command key short cuts for those of us who have become used to this approach I did however install and examine TelePaint This is a fairly standard color paint program similar in function and features to Spinnaker s Splash and Z Soft s PC Paintbrush If you don t al ready havea paint program you ll appre Say You Saw It In Modern Electronics ciate TelePaint but there s nothing in it that would cause you to switch from a paint program you already have and are used to The MousePen has two big advantages over soap bar mice that have caused me to really like it First is its Microsoft mouse compatibility Appoint includes a mouse driver on the supplied utility disk However if you already have an MS mouse installed you won t need it I just unplugged the Microsoft mouse from my PC plugged in the MousePen and every thing that used a mouse accepted the MousePen without question The second benefit the MousePen of fers is that it doesn t use much of your desk s real estate Using a standard mouse generally requires that you dedi cate about a square foot of empty desk space in which to move the mouse The MousePen makes do in an area about 2
95. e remaining circuitry Capacitors C and C4 provide low frequency filtering of the pulsat ing dc emerging from RECT for the positive and negative voltage regula tor circuits made up of JC and C2 respectively High frequency noise filtering is taken care of by C2 for IC and C5 for IC2 Relay K has its coil wired in paral lel across the primary of 77 after POWER Switch S This relay has two sets of normally closed contacts that connect separately to bleed resistors Ri and R2 across CI and C4 respec tively The purpose of these resistors Say You Saw It In Modern Electronics is to discharge the capacitors when the power supply is shut down to pre vent an output spike from occurring Positive dc power from the out put of RECT is delivered directly to POWER Indicator LED through cur rent limiting resistor R75 Any time the supply is powered up this LED will be on The pure positive dc voltage that results from the filtering action of electrolytic capacitor C7 is passed through voltage regulator JC and emerges as a tightly regulated 15 volts Capacitor C3 at this point pro vides additional high frequency noise filtering for this line In a similar manner the pure nega tive dc voltage that results from the filtering action of C4 1s transformed into a tightly regulated 5 volts by IC2 As above C at this points pro vides additional high frequency noise filtering for this line Operational amplifier
96. e carefully snipped off the IRF 511 Any general purpose npn switch ing type device can be used for the re maining transistors Fig 1 shows six such transistors You may or may not require this many depending on the number of extra area code and other digits you must dial If you do not haveto diala90ra 1 you can get by with just four transis tors an extra transistor shown as Q2 in Fig 1 is always required for shutting down the Dialer after the area code digits have been dialed If you must dial either a 9or a 1 or both you need five or six transistors If you have to dial any number combination that has repeated digits in it such as 1 815 a separate tran sistor is not needed for each digit that is repeated Simply bring the appro priate C2 counter outputs to a single transistor Make sure to use separate 1N914 diodes to isolate the common outputs though Before actually mounting the com ponents in place and wiring them to gether plan your layout on grid pa per preferably with 10 boxes to the inch to obtain an actual size layout Oncethisis done mount thetwo DIP transistor sockets in place followed by the resistors capacitors trimmer control and transistors Do not plug the ICs into the sockets until after you have conducted voltage checks and are certain that the circuit is properly wired Referring back to Fig 1 carefully wire together the components using insulated hookup wire Make ce
97. e cord as shown A photo of the completed project housed inside a plastic project box is shown in Fig 2 When you are done check all wir ing especially in the portions of the circuit where ac line voltage is to be present triacs Q7 through Q8 and re ceptacles SO through SOS Using the Interface Plug a suitable parallel connector ca ble between the parallel output port of your computer and the DB 25 con nector on the project Then plug a ta ble lamp into receptacle SO on the project and plug the Interface s line cord into an ac outlet Make sure the lamp switch is on Say You Saw It In Modern Electronics Turn on your computer and key in the BASIC program given in the list ing Save the program to disk under a filename PSWITCH BAS Now RUN the program and follow the instructions given on screen You should be able to toggle on and off thelamp plugged into the receptacle If so unplug the lamp from SO and plug it into SO2 and toggle it on and off from the keyboard of your computer Repeat this procedure un til you have checked out operation of all channels you have wired into the system If you fail to obtain toggle action in any channel power down the com puter Unplug the project from both the ac line and computer Then recti fy the problem Do not proceed to use the project until you are sure that it is operating properly ME LOW COST PC LOGIC ANALYZER Model LA1 99 95 id
98. e for handle Add insulation a E Cement to PC board Add 5 of 1 2 ID Add strain relief to cable inside pipe Fig 6 Fabrication details for probe assembly housing diameter main detector tube and ac cessory 14 inch inner diameter pipe cement to this pc board Use a good quality epoxy cement to secure the tube and pipes to the board While not essential you should place an in sulating material between the detec tor tube and outside pipe As shown in Fig 6 D cement a 5 inch length of 14 inch inner diam eter PVC pipe to the copper trace side of the circuit board assembly to use as a handle for the probe Pass the cable out the open end of the pipe Attach a strain relief to this ca bleinsidethe pipe This can bea plas tic cable tie secured in place to the wall of the pipe with hardware Terminate the free end of the cable in a connector compatible with the one you used on the main circuit board assembly Wrap the outside of the 1 inch pipe with gray duct tape or coat the pipe with a good alumi num paint such as Dow s XP 310 Checkout amp Calibration Connect the common lead of a dc voltmeter or multimeter set to the dc volts function to a convenient circuit ground point Snap a fresh 9 volt al kaline battery into its holder and set S1 to on Touch the hot probe of the meter to the OUT pins of C7 and C8 in turn You should obtain readings of 5 and 5 volts res
99. e screw in the collet driving it in until it binds firmly Cut of excess screw length Tips so constructed tend to work loose but otherwise perform well Limit tip size to smaller diameters Thermal shaping and cutting tools are frequently used in plastic arts and crafts projects You may have need for larger cutters and chisel knives best adapted to higher wattage sol dering irons Relatively compact Weller s Models WP80 80 watt iron with inch slide in tip and WP100 100 watt iron with inch slide in tip are recommended for heavy duty use in punching larger holes Cutters made from C and D size cells were adapted to the larger iron and per formed well The teacher wants us to bring a pencil to school tomorrow what s a pencil FOR THE RACK CHASSIS CONSTRUCTOR CONSTRUCTED OF ALL ALUMINUM PARTS THE FRONT amp REAR PANELS ARE CLEAR BRUSHED ANODIZED THE BALANCE OF THE PARTS ARE RU 1 75 SHIPPED FLAT UNASSEMBLEDE LAC BRUSHED ANODIZED MODEL SIZE H W D PRICE SEND For FREE JEATALOG 1RUS 1 75 x19x5 28 00 RACK CHASSIS RACK PANELS TRUF 1 75 x 19 x 7 30 00 SA rws 1RUIO 175x19x10 32 00 EN E Ea 2RUB 350x19x5 30 00 NU aca Ue 2RU7 350x19x7 4 3200 300 PROFESSIONAL AND 2RUTO 3 50 x 19x 10 34 00 SEMI PROFESSIONAL 3RUS 525x19x5 38 00 ots 3RUF 525x19x7 4000 onte dee Wou 3RUTO 525 x I9 x 10 42 00 Ms SESCOM INC uU UT TET 2100 WARD DR NEXT DAY AIR amp 20 00 702 565 340
100. eal for stud ents and hobbyists working with digital logic in the KHz range De signed for non microprocessor ap plications works where an oscil loscope DVM and logic probe are inadequate 8 channels 36 data cable 5V TTL CMOS input int ext clock full featured graphics utili ties etc Over 100 000 samples second on 12M Hz PC Demo pak 4 Greensburg LA 70441 504 748 7090 CIRCLE NO 175 ON FREE INFORMATION CARD pz ee meem mmm mm m mmm m m m m m DISCOVER EXPERIMENT ADVANCE ELECTRONICS LASERS CAD CAM HOME STUDY HOMEWORKS Now you can learn beginning to advanced electronics at home with the same courses used today in the world s top colleges and tech schools and pay a lot less You ll learn just what you want when you want at your own pace The complete story is in our free catalog Homeworks by Heathkit Order yours today call toll free 1 800 44 HEATH 1 800 444 3284 YES Please send me a FREE copy of the HomeWorks by Heathkit Catalog Heath Company Dept 601 035 Benton Harbor Michigan 49022 Send to Name Address CIRCLE NO 85 ON FREE INFORMATION CARD November 1990 MODERN ELECTRONICS 43 Project Area Code Speed Dialer Automatically dials any area code including the 1 that may be required and any digit needed in an office telephone system to access an outside line By Dave Wysock considerable portion of your workday maki
101. ed in the Parts List were selected for the prototype probe described later Ultra precision OP 177 devices are recommended for all operational summing amplifiers Specifications of the new OP 177 are significantly better than those for the famed OP 07 at about the same price For op timum operation ZC requires the tightest possible specifications which means that an OP 177 or its equal should be used here For C2 IC3 and iC4 the specifications are not as critical so you can use less ex pensive op amps even a 741 to economize 26 MODERN ELECTRONICS November 1990 Say You Saw It In Modern Electronics WWW americanradiohistorv com Fig 2 Actual size etching and drilling guide for main printed circuit board Construction If you prefer not to fabricate a pc board you can assemble the circuitry on perforated board that has holes on O l inch centers using suitable Wire Wrap or soldering hardware If you go this route make the connec tions to the meter via short cables ter minated in banana plugs and house the assembly in a small enclosure Fabricate the pc board using the ac tual size etching and drilling guide shown in Fig 2 If you do use this guide be sure to use the recommend ed battery holder and switches Begin populating the board by installing and soldering into place sockets in all DIP IC locations Do not plug the ICs into their respective sockets until after you have conducted initial vol
102. ed it We also offer FAX ordering convenient hours and multiple payment options Po pn e EAR SUP For A FREE ONE Elect e 4 800 549 MCM ELECTRONICS 650 CONGRESS PARK OR CENTERVILLE OH 45459 4072 A PREMIER Company SOURCE NO ME 56 CIRCLE NO 87 ON FREE INFORMATION CARD November 1990 MODERN ELECTRONICS 9 WWNwW americanradiohistorv com Wi NEW PRODUCTS ili For more information on products described please circle the appropri ate number on the Free Information Card bound into this issue or write to the manufacturer Universal Interface Design Aid The micro LAB computer peripheral from Fisher Instruments Bothell W A is designed to be a universal computer interface It is intended to be a design aid for use by engineers designers and students Reported to function with virtually any computer that has an RS 232 serial port operat ing at 300 to 19 200 baud with no handshaking required micro LAB can be controlled via almost any computer language Included in the micro LAB pack age are a solderless breadboarding socket function generator D A and A D converters fixed and program mable clocks counter audio ampli fier and speaker two eight bit input and two eight bit output only ports Sample applications and graphics are also provided Allinputs and outputs are TTL compatible Clock count ers include three crystal controlled clock sources three 16
103. ed to assure reliable cost effective digital hardware Tested shortcuts and techniques aad a toolkit of solutions to common problems associated with ad vanced Schottky and CMOS systems are presented Every aspect of high speed digital systeras is covered Throughout the book practical engineering approxi mations are used in place of rigorous mathematical analyses Two parts make up the book Part 1 deals with device characteristics while Part 2 deals with design and techniques for dealing with the special concerns of high speed logic Following a brief introduction Part goes on to discuss TTL and CMOS logic family characteristics interface require ments and other related matters It then explains what TTL and CMOS logic cir cuits are and discusses in separate chap ters noise margin for the two families of devices sources of transient currents and inductance and transient current effects In Part 2 topics covered include power distribution synchronous design clock distribution signalinterconnections sig nal quality system timing reset signals and unused reset signals Three appendices follow Part 2 These are devoted to conversion factors defini tions of symbols and acronyms and trademarks A glossary of technical terms closes the book Television and Video Systems By Charles G Buscombe Published by Prentice Hall Hard cover 377 pages 45 80 This large format 87 x 11 book was written to help train
104. emote transmitter The splitter and power supply can be mounted in an out of the way lo cation The splitter can accommo date up to four connections and splitters can be ganged so that up to 10 units can be operated from one power supply and one sensor CIRCLE NO 63 ON FREE INFORMATION CARD Continued on page 8I ELENCO amp HITACHI PRODUCTS AT DISCOUNT PRICES The RSO its the new solution RSOs Real Time amp Storage Oscilloscopes From HITACHI x Ne View Acquire Test Transfer and Document Your Waveform Data Introductory Price 2mV Sens 100M 3 s 25MS s on 4 channels simultaneously 100MHz 4kw x ich 2kw x 2ch Ikw x ch VC 6145 4 695 00 3 4 Channel 100MS s Model Compact Full Feature Models 40MS s 100MHZ 4kw x 1ch 2kw x 2ch 20M5 s SOMHZz 2kw x 2ch io Cost High Value Models 20MS s 50MHz 2kw x 2ch 20MS s 20MHz Ikw x 2ch RSOstrom Hitachi feature such functions as roll mode averaging save memory smoothing interpolation pretriggaring cursor measurements plotter interface and AS 232C interface With the comfort o analog and the power of digital A 26 30 V 212 Compact Series Scopes Delayed Sweep Lightweight 13lbs 3 Yr Warranty l X Modei V 1065 VC 6045 3 049 00 u z SENE VC 5025 2 295 00 This series provides many new functions such as CRT Readout Cursor measurements V 1085 1065 665 VC 6024 2 049 00 Frequency Ctr V 1085 Sweeptime Autoran
105. end MO VISA MC for immediate delivery Single kit orders include 1 50 S amp H FREE SHIPPING on orders of 2 or more All orders shipped by U S Mail COD add 4 00 Personal checks allow 21 days DECO INDUSTRIES BOX 607 BEDFORD HILLS NY 10507 914 232 3878 CIRCLE NO 82 ON FREE INFORMATION CARD CABLE T V CONVERTERS Jerrold Oak Scientific Atlantic Zenith amp many others New MTS stereo add on mute amp volume Ideal for 400 amp 450 owners 1 800 826 7623 B amp B INC 4030 Beau D Rue Drive Eagan MN 55122 Cable Converters And Descramblers Why Pay a High Monthly Fee For FREE Catalog Call or Write CABLE CONNECTION 1304 E CHICAGO ST SUITE 301 ALGONQUIN IL 60102 708 658 2365 No Illinois Orders CABLE TV DESCRAMBLERS BARGAIN HEADQUARTERS JERROLD TOCOM HAMLIN OAK ZENITH eSCIENTIFIC ATLANTA 6 month warranty We ship C O D Lowest retail wholesale prices FREE CATALOG Global Cable Network 1032 Irving St Suite 109 S F CA 94122 NO CALIFORNIA SALES ORDER TODAY 800 327 8544 CIRCLE NO 84 ON FREE INFORMATION CARD 11801 VIDEO T V NOTCH FILTERS SURVEILLANCE EQUIPMENT BROCHURE 1 00 D K VIDEO BOX 63 6025 MARGATE FL 33063 1 305 752 9202 SATELLITE TV Decoder Build your own Easy to follow instructions parts list circuit board and wiring diagram Send 9 95 ABG Enterprises 27081 E Halifax N S B3H 4MS8 ELECTRONICS KIN
106. er keyboard while you go back to the book to figure out what that little squirmy thing is that you just nicked with the scalpel You also have to pay at tention to the patient s vital signs While printing the screen dump that accompan ies this article the keyboard was locked so I could only watch while my patient went into Bradycardia slowing and missed heartbeats If I could have just gotten to the medicine cabinet I might have saved him Oh well there my mal practice insurance rates go through the roof I ll just have to raise my fees Asif having patients die on you wasn t realistic enough The Software Tool works also provides some doctors accou terments such as a surgical mask rubber gloves and even a cardboard beeper so you can return your wireless phone pages Life amp Death canrunon most MS DOS PCs It requires only 256K of RAM and can run in either graphics or text mode Graphics mode especially color graph ics is much more fun As you can tell from the accompanying screen dump the displays are not amazingly lifelike And the patients all tend to start looking the same after a little while No it s not that you stop thinking about them as individ uals but to save disk space The Software Toolworks has programmed in only three or four patients and re uses them with different symptoms and ailments I don t usually spend a lot of time play ing games on my computers I use them much too extensively
107. eres and the power source is 12 volts RJ 12 volts 0 7 volt 0 01 ampere 1 130 ohms Be sure to calculate the required power in watts for R Circuits driven by high input voltages require 4 watt or greater power ratings for the resis tor Choice of npn power transistors for the circuit is not complicated Collector breakdown voltage should be at least four times the supply volt age because the circuit can generate very large voltage spikes at the collec tors A smail value capacitor C2 wired across the primary winding of the transformer as shown can some times tame voltage spikes and help protect the transistors from damage due to large voltage transients The collector current rating of the transistors is determined by the input current of the circuit which is easily calculated once you know the input power and voltage Use transistors pP ee ee 52 MODERN ELECTRONICS November 1990 Say You Saw t In Modern Electronics WWW americanradiohistorv com TRANSFORMER DATA CORE MAGNETICS NO G42213UG FEEDBACK 1 2 3 10 TURNS C T PRIMARY 4 5 6 10 IO TURNS BIFILAR SECONDARY 7 8 33 TURNS ALL WINDINGS NO 26 ENAMELED wIRE 03 D6 IN400 15V DC ISON OUTPUT LOAD Fig 6 A practical design example of a dc to dc converter circuit that can be used for experimental purposes or incor that have a continuous collector cur rent rating of at least twice the ex pected input current
108. es In calibrat ing this adapter it is assumed that a person s hand the walls of the build ing and water havethe same emissivi ty of about 0 9 This is a good as sumption and is precise enough for general use This Infrared Thermometer Ac cessory does not have a specific ad justment for emissivity However it can be used for low emissivity mater ials like steel if you calibrate the ac cessory using the same type of mater ial at a known temperature This pro cedure is more troublesome but vast ly more accurate than guessing at the emissivity of the material Due to its nature an infrared ther mometer cannot be designed to mea sure temperatures as accurately as a contact thermometer can However this Infrared Thermometer Accessor is extremely sensitive has super fast response and can be calibrated to have an accuracy within 3 F ME Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 77 A adidi eWmereanmcadielietom com NS ELECTROMCS MART Classified Commercial Rates 1 per word 15 word minimum 15 00 prepaid Word count includes name and address ZIP code and abbreviation each count as one word P O Box number and telephone number count as two words each Indicate free cate gory heading Computers Communications Electronics Video or Miscellaneous special heading is available for a 6 surcharge First word only is set boldface caps at no charge Add 2
109. es a small offset volt PARTS LIST R10 R19 2 740 ohms R11 118 000 ohms R12 215 000 ohms R13 R15 100 000 ohms R14 84 500 ohms R17 20 000 ohms R18 1 000 ohms 5 tolerance V4 watt R4 10 000 ohm 15 turn pc mount trimmer potentiometer R16 1 000 ohm 15 turn pc mount trimmer potentiometer R20 50 ohm pc mount trimmer po tentiometer Miscellaneous B1 9 volt alkaline battery P1 P2 Banana plug IRSI 1M thermopile detector with ar gon gas and 6 5 to 15 5 micron LWP filter specify argon gas and LWP fil ter 50 2 P amp H from Dexter Re search Center Inc 7300 Huron Riv er Dr Dexter MI 48103 313 426 3291 S1 Spst pc mount slide switch Digi Key Cat No SW100 ND S2 3pdt miniature pc mount slide age to the degree calibration circuit Potentiometer R20 is used to adjust the Celsius circuit Since the IRTA Thermometer ac cessory uses a single 9 volt battery B1 and the circuitry requires both 5 and 5 volts for proper opera tion sometype of voltage conversion is required This is accomplished with LMC7660 voltage converter IC6 which converts the 9 volts from B to the 9 volts required by the summing amplifiers The 9 volts that exits at pin 5 of IC6 is unregulated It is passed through C8 which outputs a tightly regulated 5 volts The 9 volt source from BZ also goes to JC7 which outputs a tightly regulated 5 volts Thus all voltage requiremen
110. es of analog arithmetic Using Op Amps To Add and Subtract The schematic of a simple circuit that io Oi O Of INPUT CvocTS adds two voltages is shown in Fig 2 This circuit commonly called a summer or ad der is ofter used to mix two or more signals When the resistance of the feed back resistor matches that of input resis tors RZ and R2 the voltage gain of the circuit is uniry Increasing the resistance of feedback resistor Rp causes the circuit to both add and multiply The schematic of a simple circuit that subtracts the voltage at Input 2 from the voltage at Input 1 is shown in Fig 3 This circuit is commonly known as a differ ence amplifier or subtracter As in the Fig 2 circuit if the resistance of the feed back resistor matches that of the input re sistors the circuit has unity gain Besides performing addition and sub traction simple operational amplifier circuits can convert a voltage into its logarithm As we ll seeshortly these bas ic circuit functions provide the essential ingredients required for analog multipli cation and division Thelogarithm of a number is the expo nent of the number when it is expressed as a power of the base 10 For instance 10 000 is 10 or 10 raised to the fifth Es D GotPut VOLT Fig 5 Plotted operation of log amplifier circuit shown in Fig 4 58 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Say You Saw It I
111. everal rooms up and down the corridor You go to the room by using a mouse to move an arrow shaped cursor to the door you wish to enter then clicking the left hand but ton The clipboard at the foot of the the patient s bed is examined by clicking on it It then describes their symptoms all of which are remarkably similar flu like with weakness and abdominal pain The clipboard also has a variety of actions you can take You can observe the patient medicate him run an UltraSound or take an X Ray refer him to a specialist or perform surgery By moving the cursor to a box next to the action you wish to take click ing the mouse button initialing the order by clicking the initial box and then click ing off to the side of the clipboard you cause the requested action to be initiated If you rush ahead and perform any of the clipboard options right away except for observe you will be asked to attend a Hi Doctor to Toolworks General Welcome Won t you a sign Lue At the start of The Software Toolworks Life amp Death game program the opening screen has a nurse greet you as you step into Toolworks General Hospital Your patients the medical school and operating room are in rooms off the corridor lecture in the medical school which is the first door on the right of the corridor You must first perform a physical exami nation of the patient When you click on the bed cover the patient s un
112. excessive voltage drop the design should be repeated using larger size wire In some cases this may necessi tate use of a larger core e Core Geometry After a pot core has been tentatively selected for the transformer design and the total number of turns has been calculated Fig 5 can be consulted to determine the capacity of the bobbin in num ber of turns of wire for various wire sizes This graph helps in selecting the wire size to be used aslong as you remember that the minimum wire size restriction shown in Fig 4 is taken into account Bobbin winding area tabulated in square inches is found in Table 2 Figure 5 is based on just one wind ing on the bobbin Since the trans former will contain three windings the insulating tape that is to be placed between each winding will reduce the total number of possible turns you can wind on the bobbin so take this into consideration as well when se lecting core and wire sizes Calculating Turns The number of turns of wire you must wind on the bobbin is determined by such factors as operating frequency in Hz effec tive magnetic area of the core in square centimeters potential im pressed on the primary winding in volts and flux density in Gauss To simplify the procedure for de termining the required number of turns some assumptions must be made These are flux density and op erating frequency Since neither of these parameters need be precise the assumed values w
113. feedback winding now suddenly re verses causing current to flow in the initially cutoff transistor This cur rent increase which isin the opposite phase as the previous current in duces a voltagein the feedback wind ing which cuts off the current in the initially conducting transistor This cycle of events repeats at a very rapid rate which might be 5 kHz or 10 kHz Diodes D1 and D2 in series with the bases of Q7 and Q2 respectively prevent reverse polarity voltages from the feedback winding from be ing applied to the transistors This is asafety measurethat ensures that the reverse emitter to base voltage of the transistors does not exceed safe limits In operation each transistor inthe circuit acts as a switch that causes the voltage from the power source to be alternately impressed on each half of the primary winding of 77 The re sult is that a square wave with a peak to peak potential that is equalto four times the supply voltage measured from collector to collector provides excitation to the primary winding of the transformer A third winding of 77 provides step up or step down action The shape of the output waveform at this winding is also a square wave which is fed to the conventional full wave bridge rectifier circuit made up of D3 through D6 to provide the desired pulsating dc output voltage Finally filter capacitor C3 smoothes the pul sating dc from the bridge circuit to provide pure dc A great advan
114. fficiency distortion light level and so forth One of my principal interests in ratio metric measurements is comparison of the intensities of two adjacent wave lengths of sunlight Various gases in the atmosphere selectively absorb different wavelengths of visible light and ultravio let and infrared radiation By measuring the ratio of the intensity of the radiation at one of these absorption bands and a nearby non absorbing or reference band it is possible to determine the quantity of the absorbing gas in a column through the atmosphere Another use for the ratiometric mea surement technique is remote determina tion of temperature This method relies on the fact that everything in the universe emits a broad band of infrared radiation The peak wavelength of this radiation and the slope of its curve are determined by the temperature of the emitter There Analog Arithmetic A D DIG I TAL OUT PUT Ve Vin C2 Fig 1 How to divide two voltages with a microprocessor fore by monitoring the intensity of the infrared radiation at two different wave lengths it is possible to determine the slope of the curve and temperature of the object being detected Digital vs Analog Arithmetic If an electronics engineer with a digital background is asked to design a circuit to divide two voltages chances are the block diagram of the resulting circuit would re semble the one shown in Fig 1 Here each voltage i
115. fundable B amp R Enterprise P O Box 662 Portage MI 49081 PROTOQUICK Z8 single board computer with prototype area 69 00 Software Sci ence 3750 Roundbottom Road Cincinnati OH 45244 513 561 2060 a mS E cage x oce mr Me olx 78 MODERN ELECTRONICS November 1990 wwwW americanradiohistorv com Say You Saw It In Modern Electronics FREE IBM SOFTWARE CATALOG 2000 Disks Toll Free 1 800 345 2983 24 Hours In Colorado Please Call 303 934 5507 MEG A BYTE INC PC SOFTWARE SUPPLY 3691 Morrison Road Denver CO 80219 FAX 303 936 7049 ROBOTICS software PC MSDOS Explore computer vision sonar sensing Free brochure ROBOTS ETC Box 122 Tempe AZ 85280 COMMUNICATIONS MORSE Code No Problem You can in crease your speed no matter how many times you ve failed before Results guaranteed when you follow the instructions PASS Publish ing s CW Mental Block Buster program helps you explode mental blocks that hold you back Based on 40 years of research the CW Mental Block Buster uses guided meditation dynamic visualizations and powerful affirmations to blast through mental blocks You can do code That means new bands more contacts more fun This is not a CW practice tape The CW Mental Block Buster audio cassette and practice booklet are only 24 95 ppd in the US NY residents add 1 87 sales tax Quantity discounts available for classes PASS Publishing P O Box 570 Stony Brook NY 1178
116. g Wipe the tip with fine steel wool or a heavy cloth to remove the adher ing plastic If the plastic melts inside thethetip twirl a small drill bit inside the hot tip to remove it Perform trials with the powerstat or light dimmer set to 40 60 80 and 100 volts in turn At insufficient in put power heat flow down the thin walls of the tip will fail to soften the plastic At about 80 to 100 volts the tip will heat sufficiently to soften the plastic and permit you to push the tip through in2 to 4 seconds without cre ating fumes melting the plastic or fouling of thetip The holes will have little or no burrs and the waste slug will be barely deformed if at all This is the desired operating condition Usually the powerstat is set for 70 to 100 volts after initial warmup at 117 volts If you are using a solid state controller with arbitrary dial calibra tion take note of the dial indications as you determine the correct setting Figure 3 illustrates a plastic panel machined with the thermal punches At left from top to bottom the cut outs accept a phono jack miniature slide switch standard slide switch and DB9 connector At lower right the large cutout accepts a Centronics parallel printer connector The series of graduated holes at top right ac cept screws and a wide variety of jacks switches and potentiometers Use a reamer to increase hole size as required Below are several holes punched with the squared cutters
117. ging and VC 6023 1 749 00 Trigger Lock using a 6 inch CRT You don t feel the compaciness in terms of performance and operation V 660 60MHz Dual Trace 1 195 Hitachi Portable Scopes V 665 60MHz Dual Trace w Cursor 1345 wea 435 DC to SOMHz 2 Channel DC offset V 1060 100MHz Dual Trace 1 425 oC to zoMH function Altemate magnifier function V 1065 100MHz Dual Trace w Cursor 1 695 Dual Channel V 525 CRT Readout Cursor Meas 1 025 V 1085 100MHz Quad Trace w Cursor 2 045 V 523 Delayed Sweep 995 V 1100A 100MHz Quad Trace w Cursor 2 295 422 40MHz Dual Trace 795 V 522 Basc Model 5895 V 1150 150MHz Quad Trace w Cursor 2 775 Repeater system provides remote 20MHz Elenco Oscilloscope FREE DMM Elenco 35MHz Dual Trace 375 with purchase of to 50MHz 495 control of multiple room i 22 ba ANY SCOPE NEL AL Fa N Dual Trace e imV Sensitvi tems OF use m situations W ere a x rss en Tester SCOPE PROBES TRE uA rect line of sight for infrared remote control is not practical It consists of mes 2 p 1 Probes Ante All scopes include probes Schematics operators manual and 3 year 2 yrs for Elenco scopes world wide warranty on parts amp laeor any accessories available for all CAT PAG Ww 10ns Arse Time Hitachi scopes Call or r write tor complete specifications on these and many other fine oscilloscopes ROAR Remote Optical Amplified X Operation P 69MHz Ix 10x
118. hapter one simply looks up a given symptom which is followed by a paragraph on the prob able cause and one or more paragraphs that detail how to localize the trouble Only two chapters are specific to the VCR One discusses the various VCR components magnetic recording funda mentals microprocessor and system con trol etc The other covers troubleshoot ing maintenance and repair of both elec tronic and mechanical problems All in all this well presented well rounded book lives up to its title and sub title The text is terse without being dry It is excellently illustrated with schematics drawings block diagrams and photos Every chapter closes with a battery of questions numbering as few as 10 up to almost 40 to test the reader s grasp of the topic discussed No formalized answer key is provided though This is an excel lent first troubleshooting book that is likely to be frequently used even by old hands who are experienced in trouble shooting maintaining and repairing con sumer video equipment Wi NEW LITERATURE Test Equipment Catalog The Tek Di rect Catalog allows buyers to order test and measurement equipment directly from Tektronix Among the items listed and fully described are hand held and low end portable oscilloscopes printers accessories software and training aids These products cover a price range from 150 to 5 000 Special product offerings in the form of discounts and free prod
119. he IDT49C460 and IDT39C60 which are single bus units The IDT49 C460 32 bit EDC has decreased error correction time from 30 ns to 18 ns a speed improvement of 40 percent while the IDT39C60 16 bit EDC has decreased error correction time to 25 ns which is 17 percent faster than before Again using modified Hamming code the IDT39C60 and IDT49C460 can de tect all single bit hard and soft errors and correct them within a single cycle Dou ble bit errors can be detected more than 50 percent of the time In the early 1980s EDC circuits were found almost exclusively in commercial mainframe and minicomputers and avi onics flight computers With constant price decreases and availability of faster speeds EDC circuits will be accessible to new markets such as single user work stations and personal computers Available now at 18 ns correct time the IDT49C460 is offered in 68 pin plas tic leaded chip carrier PLCC packages In a PLCC package the 18 ns version of the IDT49C460 sells for 98 50in 100 and up quantities The IDT39C60 is offered in 48 pin plastic and ceramic DIP and 52 pin PLCC and LCC packages The 25 ns correct time version sells for 41 25 packaged in a plastic DIP in 100 and up quantities Error Correction Vs Parity Checking Computer system builders have always faced the decision of how to handle mem ory data errors In memory systems two types of error can occur hard and soft A
120. he OUT PUT LEVEL control clockwise while monitoring the reading indicated on the exterral meter The output po tential from the power supply should reach 9 volts when this control s knob is fully clockwise and the RANGE Switch is set to HI The volt meter on the Power Supply should now verify this reading If so set the RANGE switch to the LO position and verify via both meters that the output is 150 millivolts If all checks out well to this point connect a 10 ohm 10 watt resistor across the OUTPUT binding posts or banana jacks Set the RANGE switch to HI and the OUTPUT LEVEL panel control to fully counterclockwise Turn on the Power Supply and slow ly adjust the knob on the OUTPUT LEVEL control clockwise while ob serving the panel meters You should observe both pointers steadily rise from minimum toward maximum until the control reaches full clockwise rotation At this point the output potential from the Power Supply should be approximately 9 volts and output current should reg ister approximately 0 9 ampere The load resistor will get warm rather quickly so do not maintain this test for an extended period When you are finished testing the Precision Low Voltage DC Power Supply finish assembling it You now have a Power Supply that will provide the precise power required for your most demanding low volt age testing andexperimenting ME Say You Saw It In Modern Electronics Project Stereo Audio Test Bo
121. he area just above R10 see Parts List Carefully examine the circuit board assembly to make certain that all components are installed in the proper locations and that those that require polarization and special bas ing are properly installed Turn over the circuit board assembly and care fully check your soldering Solder any connections you may have missed reflow the solder on any suspicious connections and remove solder bridges especially around the closely spaced IC socket pads with a va eee p mo e p pum EU Uwe aec E e EN UG CNN November 1990 MODERN ELECTRONICS 27 NMww samericanradiohistorv com Cement lead of IC5 to case lead of P Output pin Pw EE Fig 4 Epoxy cement top of LM335 1C5 to bottom of thermopile detector IC5 cement to case of IRS1 Output pin Output pin 4 i IRS1 Cement IC5 lead to IRS1 case RSI case and connect together leads as illustrated cuum type desoldering tool or desol dering braid Then temporarily set aside the circuit board assemblv Though the design of the basic cir cuitry is fairly straightforward if you use an ultra precision op amp like the OP 177 for C probe design is simple but not trivial As shown in Fig 4 begin fabrication of the probe by cementing with fast setting epoxy cement the top of the case of C5 to the bottom of the case of JRSJ Posi tion the two devices
122. her environmental haz ards When used to repair solder masks the pen is reported to improve the reliability and safety of pc modi fications ard repairs The conformal polymer overcoat material is available in several colors including green and clear The mate rial is designed to match the durabili ty and color of solder masking mate nals to assure nearly invisible re pairs It dries in 5 to 10 minutes at room temperature and can be cured at 50 to 100 C to enhance overall performance It is claimed to have excellent adhesion to pc materials and to be safe to use on gold silver copper and solder alloys When not tn use the pen s spring loaded tip closes to prevent drying and clogging The tip is self cleaning and enough coating material is in cluded to insulate and protect 60 feet of exposed wide trace on a pc board 9 95 CIRCLE NO 62 ON FREE INFORMATION CARD Infrared Repeater Sonance s San Clemente CA new to prevent false triggering from am bient sunlight or a lighted fireplace The sensor and emitter are available in standard Decora and Decora Lens styles the last using a larger lens for better off axis transmission and reception Agc circuitry increases the sensor s sensitivity in proportion to the in crease in distance between it and hand held remote transmitter An ul tra bright LED visible through the sensor lens gives visual indication that the module is receiving data from the r
123. ic parts of cooking utensils toasters and steam irons Non reinforced types are very brittle Products reinforced with fi berglass cloth or fibers are nearly un breakable Plastics including glass and silica fillers quickly dull drill bits The relatively hard plastic is easily drilled but may tend to chip when the drill breaks through and large holes are usually a bit difficult to machine Recommended for thermal punch ing is a 40 to SO watt soldering iron that accepts 4 inch diameter slide in tips A typical example of such an iron is the Weller Model SP40 40 watt unit shown in the lead photo You can easily make any needed adapters and tools using 4 inch brass or alu minum shafts shaft collars spacers and hubs salvaged from TV tuners radios and the like Multi deck wafer switches yield assorted spacers and metal inserts of knobs yield 4 inch collars The metal hubs of wheels and gears of tuning mechanisms yield col lars and V4 inch shaft couplers Shaft couplers shaft extenders and collars are usually available from companies that cater to amateur ra dio needs The thin wall hard brass tubing of TV rabbit ears antennas provides durable high strength cut ting tips A single ear of such an antenna usually consists of four sec tions of tubing measuring about 2 554 As and 4 inch in diameter all of which can be put to good use as ther mal hole punches Shown in Fig 1 are four thermal punches of a
124. ical isolators Af ter cutting the cable to length re RI 220 220 3 Pl o T p OW OF OO og ooodo yF DB25P oOo0o0o0oc 11 A EEEE LLIELEL FRONT VIEW PARTS LIST Semiconductors IC1 thru IC MOC3010 optical isola tor Radio Shack Cat No 276 134 or equivalent Q1 thru Q8 400 volt 6 ampere or greater triac Radio Shack Cat No 276 1000 or similar see text Resistors R1 thru R16 220 ohms watt Miscellaneous P1 Solder type DB 25P male connec TO ADDITIONAL STAGES sEE TEXT tor Radio Shack Cat No 276 1547 or similar SO1 thru SO8 Chassis mount three conductor snap in ac receptacle All Electronics Printed circuit board or perforated board with holes on 0 1 inch centers and suitable Wire Wrap or soldering hardware ac line cord with plug en closure Radio Shack Cat No 270 224 or similar see text spacers rub ber grommet machine hardware hookup wire solder etc Fig 1 Complete schematic diagram of the Computer Controlled AC Interface circuit move and discard one conductor Then separate the conductors at one end of the cable a distance of 1 inch and as needed at the other end Strip inch of insulation from all conduc tors at both ends of the cable Tightly twist together the fine wires at both ends of each conductor and sparingly tin with solder Use heat judiciously as you do this to minimize fusing and charring the in sulation Cr
125. ignal being recorded and endless playback of both sides of a tape Dolby B noise re duction is provided for both decks Timer record play permits the pro gramming for later operation PLL synthesized tuning with direct entry and 10 presets is featured in the AM FM stereo tuner A low noise AM loop antenna and a timer are included The speakers feature a 4 inch midrange driver l inch tweeter and Yamaha s YST air woofer The cloth speaker grilles are in an offset pear shape to leave visible the open throats of the air woofer ports Other system features include a balance control and LEDs that show volume level Except for the rotary Volume and slide type equalizer and balance controls all functions are operated via pushbuttons An in cluded 34 button infrared remote controller duplicates virtually all control functions on the console unit 999 CIRCLE NO 52 ON FREE INFORMATION CARD High Speed DSOs Hitachi now has two new lines of high speed digital storage oscillo scopes Its 65 and 75 series DSOs share such common features as 100 MHz analog digital bandwidth two channel simultaneous sampling 2 mV div sensitivity eight bit verti cal resolution 4K record length 100 ns glitch capture averaging and roll modes cursors readout and save memory sweep time autoranging and built in IEEE 488 GPIB inter face All models also include pre post triggering trigger lock digital processing and four color HPG
126. ill work very nicely in the design of the transformer Operating frequency is assumed to be 10 kHz Since the actual operating trequency of the final design is a Say You Saw It In Modern Electronics INPUT VOLTAGE Eln OUTPUT LOAD VOLTAGE E put e Fig 4 Detail illustrates primary and secondary winding resistance of transform er with its IR voltage losses E and E function of the inductance of the pri mary winding and the load it may be more or less than 10 kHz If the actu al frequency is too far out of the de sired range the number of primary turns can be increased to reduce fre quency or decreased to raise frequen cy If the number of turns is reduced the flux density of the core should be recalculated using the expression be low for N to verify that it does not exceed 4 000 Gauss Since you are dealing with square wave operation in your dc to dc con verter there is no need to preserve linearity of the transformer This be ing the case the desired flux density can be selected over a fairly wide range A large flux density permits fewer turns on the winding Of course the trade off is that as flux density in creases so do core losses and exces sive core loss can result in overheat ing of the transformer core For the Type G magnetic material used in this design the saturation flux density specified by Magnetics is 4 000 Gauss For a dc to dc convert er transformer design you c
127. imp and solder the end of the cable opposite that which the conductors have been separated only 1 inch to the appropriate points on the circuit board assembly With the circuit board assembly fully wired carefully check it over to make certain that it is accurately wired Remember that full 117 volt Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 41 uc Pr MAMMA eSEmercanrecibietaE COM a e a ee ee ee Fig 2 Interior view of completed project housed inside plastic project box BASIC Program For Operating Computer Controlled AC Interface CLEAR CLOSE KEY BYTES 0 0 OFF 0 LOCATE 1 21 PRINT Z LOCATE 2 21 PRIN LOCATE 3 21 PRIN LOCATE 10 15 PRI LOCATE GI 15 yPRE LOCATE 12 29 PRE LOCATE 5 29 PRI qu T NT NT NT NT CLS DEC 0 OUT 888 DEC 0 0 0 0 o DDDDDDDDDDDDDDDDDDDDDDDDDDDDDD PARALLEL INTERFACE PROGRAM 3 DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDY BIT NUMBER 7 6 5 E 2 1 pos DDDDDDDDDDDDDDEDDDEDDDEDDDEDDDEDDDEDDDEDDD4 3 3 3 3 3 3 3 a A A A A A A A A LOCATE 14 q 15 PRINT VALUE a BYTES LOCATE 21 267 PRINT DELAY TIMER 5 WH BOCATEw2 265 PRINT LOCATE 21 1i PRINT A INKEYS IF A IF A 0 THEN IF A 3 THEN IF AS 6 THEN IF AS lt gt CHR 13 BYTES 0 0 DEC 0 BITO 0 BIT4 0 BIT5 IF A CHR 27 IF BITO 0 THEN GOTO 399 IF BIT1 O THEN GOTO 390 IF BIT2 0 THEN GOTO 390
128. in with solder Draw the free end of the ribbon ca ble coming from the circuit board as sembly out through the slot for the DB 25 connector Referring to the Say You Saw It In Modern Electronics mp Fee ecient tie schematic diagram carefully soldera suitable length of solid bare hookup wire across the sides of pins 18 through 25 of the connector These are the pins shown connected at the lower right of the connector in the schematic Then carefully solder the ground wire coming from pin 2 of both optical isolators to any one of these pins Solder the free ends of the remain ing conductors in the ribbon cable to pins 2 through 9 of the connector as shown in the schematic When sol dering any of the ribbon cable con ductors into place use heat judi ciously to minimize heat damage to the insulation When you are finished wiring the connector carefully check it over Reflow the solder on any pin that ap pears suspicious Check particularly for solder bridges between the closely spaced pins of the connector If you locate any clear it with desoldering braid or a vacuum type desoldering tool Then mount the connector in its slot in the end wall of the enclosure with suitable machine hardware Wire the receptacles into the cir cuit by crimping and soldering the free ends of the heavy duty leads coming from the circuit board as sembly to the lugs on the receptacles Finally wire into the circuit the ac lin
129. ine cord through its rubber grommet lined hole and tie a strain relieving knot in it a suitable distance from the unpre pared end inside the enclosure Crimp and solder the two conductors to the two lug terminal strip mounted in place via the hardware that secures the power transformer to the enclo sure Finally wire together the pri mary circuit of the power transform er An interior view of the finished prototype of the project is shown in the photo in Fig 3 Calibration amp Use You need a dc voltmeter or a multi meter set to the dc volts function to calibrate the Power Supply Set the meter to safely accommodate at least 15 volts of input Connect the com mon lead of the meter to the negative black OUTPUT binding post or ba nana jack Then connect the hot meter lead to the red binding post or banana jack Set the POWER switch to off and the RANGE to its LO position Rotate the knob on the WWW americanradiohistorv com OUTPUT LEVEL control fully counter clockwise Plug the Power Supply s line cord into an ac outlet and set its POWER switch to on Monitor the meter display as you adjust the setting of trimmer potentiometer R9 until the output reading from the Power Sup ply is as close as possible to 0 volt This done set the RANGE Switch to HI and verify via the voltmeter or mul timeter that the output of the Power Supply is still O volt Slowly rotate the knob on t
130. ing too Soider any connection you missed and reflow the solder on any suspicious connection If you locate any solder bridges especially around the pins of the IC sockets clear them away with desoldering braid or a va cuum type desoldering tool Checkout amp Use Connect the common lead of a dc voltmeter or multimeter set to the dc volts function to any point in the cir cuit that is supposed to be at ground potential Snap a fresh 9 volt battery into the connector Press and hold S7 closed Touch the hot lead of the meter to pins 4 and 8 of the C7 sock et and pin 16 of the C2 socket The meter should indicate approximately Say You Saw It In Modern Electronics rece RE Keo 5 volts at all three IC socket pins Release S If you do not obtain the correct reading at any socket pin disconnect the battery from the circuit and cor rect the problem before proceeding Once you are certain that the circuit is properly wired plug the 555 timer chip into the JC socket Make sure the timer is properly oriented and that no pins overhang the socket or fold under between IC and socket Crimp and solder one lead of a 470 ohm 4 watt resistor to the cathode lead of a light emitting di ode Then solder one end of a 5 inch long stranded hookup wire to the an ode lead of the LED Tack solder the free lead of the resistor to any conve nient point in the circuit that is at ground potential
131. ing a Tech Serv Authorized Computer Repair Center in your market area DOCUMENTATION TRAINING Hands on training IBM Compaq Apple and compatibles at 3 separate levels 8086 8088 Based Machines DOS System Configuration and upgrades Level 2 80286 80386 Machines Letter Quality and Laser Printers We provide manuals schematics documen Level 3 System Networks Configuration tation and advanced diagnostic software NEW HARDWARE CPU s IBM Apple Compaq and others Printers Okidata Epson Hb Lasers and others at huge discounts PARTS amp BOARD REPAIR Single source for parts and board repair 24 hour express turnaround Installation and Repair FINANCING Available for qualified businesses OVER 125 DEALERS WORLDWIDE Find out why more and more electronic professionals are adding compuler repair to their businesses or starting their own com puler repair businesses Call Tech Serv at 212 967 1865 now tecncerv SS SS o Wi SERVICING THE WORLD OF MICROS 253 West 28th Street New York NY 10001 CIRCLE NO 93 ON FREE INFORMATION CARD 1989 Tech Serv Corp LEARN ELECTRONICS FROM VHS VIDEO TAPES Our Video Tapes LdXe Are Designed a M To Make Learning Electronics Fun and Easy PART 1 DC 53 min Electronics and You V T 201 PART 2 AC 71 min Electronics and You V T 202 PART 3 SEMICONDUCTORS Electronics and You VT 207 PART 6 OSCILLA
132. ion of the best type of material depends on such fac tors as operating frequency core loss operating temperature and per meability For the Fig 1 dc to dc converter transformer design the Type G ferrite material supplied by Magnetics provides very low core loss and high saturation flux density properties both of which are benefi cial to the final result e Selecting a Core As would be ex pected the size of the core is a func tion of the amount of power that can be safely handled by the transformer Fac PCM CR IG AMI Ee CUeLCR dFR I EUR DUI ee See ESS y 1 63 To calculate power you must know the dc output voltage and load cur rent Taking into consideration the efficiency of the circuit input power can then be calculated Because it is difficult to accurately predict the ef ficiency of the final circuit design an approximation is used As a conser vative estimate assume a 70 percent efficiency Transformer power input isthen calculated as P E x I 0 7 where Pisinput power Eis output dc voltage and 7 is output dc current Manufacturers of magnetic cores supply charts or graphs that make it possible to select a suitable core in ac cordance with the power require ments of the design A graph that il lustratesthe power handling capacity of pot cores as a function of operat ing frequency and core size under ty pical operating conditions is shown in Fig 3 Using Fig 3 the appropriate core for a given
133. iques are said to accurately measure low frequen cies by measuring the period and dis Video Imaging Software MFJ Enterprises Mississippi State MS MFJ 1289 MultiCom IBM compatible software lets users of the MFJ 1278 transmit and receive mul tiple gray level weather fax maps SSTV pictures and AP news photos With it you can also transmit and re ceive full color packet pictures The package gives 80 One Key Macros and Call Alert that sounds an alarm when a preselected character sequence is received by the MFJ 1278 Auto Set lets you instantly switch modes without having to retype com mand parameters Auto Router lets you store digipeater node routes for instant digipeating Packet Multi Plex lets you send and receive a pack et message during a binary file trans fer so that you can exchange pro grams without your QSO being com pletely cut off Also included is Mul ti Word a word processor specifical ly designed for multi mode commu nications With it you can bring up a text file from within MultiCom and transmit any portion directly from that file Multi Word can also be used for everyday word processing MultiCom lets you integrate an op tional MFJ 1292 Picture Perfect Vid eo Digitizer so you can shoot and transmit a video picture via SSTV fax or packet With this program you also get menu control of your entire disk disk utilities for graphics screen cap ture and conversion to packet picture f
134. ividers As was demonstrated earlier two num bers or voltages can be multiplied by add ing their logs Figure 7 shows how this can be accomplished electronically The two voltages are first converted into their respective logarithms Then the two logs are added by asumming amplifier Final ly the output of the summing amplifier is converted back to linear form by an anti log amplifier Division can be accomplished by sub tracting the log of the divisor from the log of the dividend Figure 8 shows how this is doneelectronically The circuit is essen tially identical to the multiplier circuit in Fig 7 except that the summer has been replaced by a difference amplifier The ADS534 is a hybrid microcircuit that includes 12 laser trimmed resistors for high accuracy This remarkable cir cuit which has been accurately desig nated a single chip analog computer in cludes log and antilog amplifiers that can be connected in various ways to multiply divide square and extract square roots Figure 9 shows how the chip is connected to implement each of these functions The accuracy of the AD534 is consider SUBTRACTER x Y Fig 8 Diagram of function blocks of a logarithmic divider ably better than that of any logarithmic circuits I have fashioned from separate components The following table shows the operation of an AD534 connected asa multiplier and square rooter X X ADS34 410X AD534 l l 0 95 3 16 3 09 Z 4
135. k in within the pre scribed amount of time it is assumed to be out of control A watchdog timer stops the processor automatically then resets and starts it The D51239 has provisions to monitor power If the volt dc power supply dips out of tolerance a warning signal inter rupts the processor permitting storage of vital information in nonvolatile RAM for an orderly shutdown and graceful re start The chip s circuitry also converts SRAM into nonvolatile memory that is lithium backed The D51239 MicroManager Chip Plus Kickstarter is list priced at 3 50 in 1 000 piece quantities Enhanced PROM amp SPROM Raytheon Co Semiconductor Div 350 Ellis St P O Box 7016 Mountain View CA 94039 has announced the R29771 and R29773 4 096 x 8 32K standard bi polar PROM and Jpower switched SPROM These two devices are im proved replacements for the R29671 and R29673 PROM and SPROM The R29771 has a maximum access time of 55 ns compared to 70 ns with the previous device and an enable access time of 35 ns over the full commercial temperature range The R29773 is the SPROM equivalent to the R29771 PROM In the power down mode there is a 75 percent power savings with an access time of 55 ns maxi mum and an enable access time of 85 ns The built in power switching capability is accomplished by on chip power switches that turn off most of the internal circuitry for devices that are not selected Both devices are manufac
136. ke any other school NRI gives you hands on programming experience with a powerful IBM compatible West Coast com puter system including 2400 Only NRI gives you an IBM compatibie computer with modem 640K RAM disk drive monitor and software BASIC Pascal C TE ZIF nd PODIUM baud internal modem 640K RAM disk drive monitor and invaluable programming software BASIC Pas cal C and COBOL all yours to keep You get the experience and the know how the computer and the software to get to the heart of every programming problem design imagi native solutions then use your choice of four key computer languages to build original working programs No matter what your background NRI gives you everything you need to succeed in programming today s top growth computer career field You need no previous experience to build a successful programming career with NRI training Indeed your NRI lessons start by walking you step by step through the fundamentals giving you an expert understanding of the programming design techniques used every day by successful micro and mainframe programmers nd then the fun really begins C and COBOL Then rounding out your training you use your modem to talk to your instructor meet other NRI students even download pro grams through NRI s exclusive pro grammers network PRONET Your career in computer programming begins with your FREE catalog from N
137. kups to make to the project When you mount the binding posts into place be sure to use insulating hardware so that none comes into electrical contact with the metal enclosure Also place a solder lug on each mounting post Next mount the switches in their respective locations Then refer back to Fig 1 and wire together the switches and binding posts for each channel Use heavy duty insulated 14 gauge wire for all wiring Strip 4 inch of insulation from both ends of each wire tightly twist together the fine conductors at both ends and 38 MODERN ELECTRONICS November 1990 wwwW americanradiohistorv com sparingly tin with solder Terminate the wire ends that go to the switch lugs in suitable insulated quick dis connect crimp terminals Then crimp and solder the wires to the appropri ate solder lugs on the binding posts and slip the connectors onto the switch lugs Mount two adhesive backed tie mounts to the floor of the enclosure for each resistor Space these far enough apart to assure that the two resistors will not touch each other when mounted into place Figure 2 shows how each resistor secures to the floor of the enclosure via two tie mounts and plastic cable ties Again using 14 gauge stranded wire connect the resistors into the circuit Refer to Fig 1 for details on how to do this When you are done make sure that neither resistor phys ically touches the floor of the enclo sure Each should be spaced sligh
138. l am not completely delighted I may return the manual within I5 days and receive a prompt refund Updates will be sent 4 5 times a year they are up to 120 pages each and cost 25 per page Cancel anytime Special bonus limited time only Prepaid orders receive first supplement FREE Order today O Visa MasterCard Check enclosed Bill me manual after the Card Exp date 15 day trial period F Signa and receive a 3 Signature and prompt refund hls oes ree Name I Ade LL a_n lM City State Zip Sorry orders from foreign countries can only be accepted if they are prepaid in US currency Shipping and handling cost 15 00 per international shipment Except Canada and Mexico 97 Indian Field Rd E Greenwich CT 06830 R PL LAT ETL OTTAA CIRCLE NO 99 ON FREE INFORMATION CARD WWMLamericanradiohistorv com You wont need to search for books magazines and manu for only 4995 plus 5 00 shipping and handling aU poe BI MODERN ELECTRONICS NEWS iil PERSONAL DIGITAL CELLULAR PHONES Next year NYNEX Mobile will introduce wireless personal telephone service PTS in New York City It ll use a new digital transmission standard and expand the breadth of cellular telephone services It will buy switching equipment from AT amp T Network and digital phone handsets from Qualcomm Inc for resale to consumers It s reported that the new phones will be significantly smaller and lighter tha
139. lar ies and allows the system to be used with OS 2 UNIX DEC dumb ter minals emulators and custom OEM applications The system features concurrent operation of voice recognitior key igi 7 Uo NO e M xe i Tai SW MS i ec ot c eco CIRCLE NO 76 ON FREE INFORMATION CARD board or barcode under the MS PC DOS operating system It transpar ently operates with standard applica tion software A word boundary in dicator provides status of existing noise levels and proper classification of spoken words The system is fully compatible with IntroVoice VI vo cabularies It uses an 8086 8088 compatible NEC V 25 microproces sor operating at 8 MHz and comes PAIA Electronics Edmond OK has reintroduced its Hyperflanger and Chorus Unit analog sound pro cessing unit An extremely quiet de vice it is useful both in a studio and for live processing A hyper triangu lar control oscillator permits both linear time sweeps and exponential time sweeps that human ears pre fer both adjustable over a range of 71 1 An exclusive resonance lock circuit allows a user to hang regener ation on the edge without having to worry about breaking into feed back howls Designed to mount in a single 1 75 standard rack space the Hy perflanger and Chorus Unit requires a power supply rated to deliver be tween 12to 15 volts at 200 mA The kit includes pc board all com ponents co
140. lor e Title hot stamped in gold silver MODERN ELECTRONICS Jesse Jones Industries Dept Mod E 499 East Erie Avenue Philadelphia PA 19141 Please send Cases O Enclosed is C Charge my Minimum 15 C American Express Visa O MasterCard 1 Diners Club Card Signature binders for Modern Electronics Magazine Free personalization foil for index ing year e Cases V notched for easy access Binders have special spring mech anism to hold individual rods which easily snap in This allows magazines to be fully opened for easy readability Quantity Cases Binders One 7 95 9 95 Three 21 95 27 95 Six 39 95 52 95 Add 1 per case binder postage and handling Outside USA 2 50 per case binder U S funds only Exp Date Charge Orders Call TOLL FREE 7 days 24 hours 1 800 972 5858 Print Name Address__ NoPO Box Numbers Please City State Zip building the Speed Dialer to auto matically key in the number 9 1 725 connect the wires from Q3 to the C3 and R3 pads the wires from Q4 to the Cl and Ri pads the wires from Q5 to the C1 and R3 pads the wires from Q6 to the C2 and Ri pads and the wires from Q7 to the C2 and R2 pads on the keypad assembly When you are finished wiring from the circuit board assembly to the keypad or terminal strip mount the switch es in the hole s you drilled for it them Then use double sided foam tapeto
141. much larger CAD CAM computer aided drafting computer aided manufacturing computers A particular boost for PCs in the elec tronics area has been the great increase in symbol libraries Consequently a user can quickly pluck a variety of electronic device drawings from a library and place them anywhere in a work area It be comes easy to create interconnects enter text edit drawings etc Sophisticated software programs allow PCs to simulate circuit operation design chips and even do limited modeling and analysis With PC schematic programs now sell ing for under 100 wedding electronics and computers is not even costly today for anyone who wants to become CAD trained or draw schematics for personal or educational reasons Costlier pro 8 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com grams open new vistas which include professionally created schematics and pc board layouts Moreover one can add symbol libraries for non electronic draw ing applications such as landscape archi tecture bathroom design etc For high quality work you need good performance equipment of course You won t get it with an old 4 7 MHz comput er with 255K user memory a CGA video monitor and a nine pin dot matrix print er Also you will definitely need a mouse pointing device Some indications of how professionals use CAD CAM CAE is revealed in a re cent study by CAD CAM Publishing 841 Turquoise St Suite D Sa
142. n Sci Atlanta Pioneer amp MORE OUR PRICES ARE BELOW WHOLESALE CABLE PLUS 14417 Chase St 481 C Panorama City CA 91402 1 800 822 9955 Other Info 1 818 785 4500 NO CALIF SALES DEALERS WANTED Cable TV Descramblers If you find a better deal l we ll better our deal ae Jerrold Tocom Hamiin Oak Sclentific Atlanta Zenith Ask about our extended warranty program COD Visa M C welcome Free Call Free Catalog Video Tech 800 562 6884 3702 S Virginia St Ste 160 304 Reno NV 89502 CIRCLE NO 96 ON FREE INFORMATION CARD ATTENTION EASY WORK EXCELLENT PAY Assemble products at home Details 1 602 838 8885 Ext W 11147 ATTENTION Postal Jobs Start 11 41 hour For application info call 1 602 838 8885 Ext M 11147 6am 10 pm 7 days TOCOM VIP TEST CHIP For Models 5503 VIP and 5507 Unlike any other turn on this one works Easily installs in just seconds 50 00 each No Calif sales Call 213 867 0081 CABLE DESCRAMBLERS Jerrold 400 450 Tri Bi SB 3 Scientific Atlanta Oak To com Lowest Prices Example Jerrold from 25 00 No Calif Sales Call us last and see 213 867 0081 ZENITH Z Tac Special test board installs easily in minutes and turns on decoder for all modes Great for flashing problems Only 50 No Calif Sales Call 213 867 0081 CABLETV CABLE TV Brokers and Distributors High volume of DESCRAM
143. n e Exceptional Quality All books are qual EL rr snnt ity publishers editions especially selected by our Editorial Board E 2925P 9 95 2800P 16 95 1938 60 00 n Counts as 3 oa Hanae FREE wh en you join id f I Lai THE PLLA STRATED PROJECTS 15 Easy Electronic D tontHom SUME Projects From Delton T Horn Electronic Projects FGIL BOOK Projects you can build some unique some oid favorites from Dadiyo Bullen ard Tesh the author s vast treasury of ur Owen System electronics know how 7P 24 95 Counts as2 i LIS ie eite 3374 24 95 Counts as 2 2863P 17 95 Lal Piease accept my membership in the Electronics Book Club and send the 5 volumes listed below plus my FREE copy of Delton T Horn s All Time Favorite Electronic Projects 3105P billing me 4 95 If not satisfied may return the books within ten days without obligation and have my membership cancelled i agree to purchase at least 3 books at regular Club prices during the next 12 months and may resign any time thereafter A shipping handling charge and sales tax will be added to ail orders 3285 25 95 Counts as 2 1536P 11 95 2809 29 95 804P 21 95 Counts as 2 Counts as 2 HOw MAKE BRD VAR UWN i PRINTED CIRCUIT BOARDS E MR 3 4 of XT SAVE 4 BUNDLE S N Wae oo 7 with 17 Projects APPLI
144. n of the supply voltage A bene fit of a transformer operated circuit like this is the isolation it provides be tween the input and output circuits which is a very valuable asset for ex ample when using the ac line as the source of power The transformer in this type of circuit is usually made us ing ferrite magnetic material Ferrites are dense homogenous ceramic materials that typically con tain iron oxide and such other metals as manganese zinc nickel or magne sium They are processed by com pressing and firing at temperatures of 2 000 degrees F into various shapes to produce a hard brittle magnetic Fig 1 Schematic diagram of a typical dc to dc converter circuit 48 MODERNELECTRONICS November 1990 WWW americanradiohistorv com Say You Saw It In Modern Electronics ty FERRITE CORE HALF PLASTIC BOBBIN Fig 2 A ferrite pot core is composed Of two precision machined ferrite halves and a plastic bobbin on which the turns of an inductor or trans former are wound material that can be machined to the desired dimensions and finish Ferrite as a magnetic material has some very real benefits when com pared to the iron based materials more commonly used Ferrites exhib it high electrical resistivity and signi ficantly lower eddy current losses They can be used at frequencies rang ing from less than 5 kHz to beyond 50 MHz Furthermore ferrites provide high permeability a
145. n Diego CA 92109 which publishes a monthly newsletter Computer Aided Design Re port It indicated that 47 percent of sys tem owners plan to add work stations for producing schematics while 51 percent plan such an expansion for PCB layout The most popular electronic engineering applications for CAD are according to the study drawing schematics 40 PC boards 34 logic simulation 1370 analog simulation 10 IC layout 10 timing analysis 10 and fault simulation 8 To get a better feel for what s available in schematic drawing and printed circuit board layout programs in the personal computer world we examined a batch of them from ones at low price points to more costly packages Additionally we worked with an educational software package that simulates circuit activity through output readings of software generated instruments of all kinds And we varied the type of computers and peripheral equipment used The results of these efforts will be de tailed here starting next month I think you will find it to be both interesting and inspirational since it s a field of endeavor that weds electronics and computers and offers growing job opportunities Dit Lao Say You Saw It In Modern Electronics LETTERS NE Equivalency Would you please supply me with equivalent numbers for CMOS op amp C and 3914 dot bargraph display driver C2 for the Biofeedback Monitor amp Lie Detector
146. n Modern Electronics a eid Fig 6 Schematic of a simple antilogarithmic amplifier power Therefore the logarithm of 10 000 is 5 and 437 is 102 569 which yields a log of 2 8669 Two analog voltages can be multiplied or divided if they are first converted into their respective logarithms Multiplica tion is accomplished by using a summing amplifier to add the logarithms of the two numbers The antilog of the sum is the product of the two voltages Division is accomplished by using a difference am plifier to subtract the log of the divisor from the log of the dividend The antilog of the difference is the quotient of the two voltages Inserting a non linear element such as a diode or transistor into the feedback of an op amp transforms the circuit from a linear to a logarithmic amplifier Figure 4 shows one commonly implemented ver sion of the basic op amp logarithmic am plifier A breadboard version of this cir cuit gave the following outputs for a range of input voltages Input Output volts volts 0 001 0 322 0 010 0 371 0 100 0 432 1 000 0 494 10 000 0 557 The output voltage is inverted negative because the op amp is connected in its in verting mode Polarity can be ignored or changed to positive by adding an invert ing buffer stage Y o ADDER x Fig 7 Diagram of function blocks of a logarithmic multiplier Say You Saw It In Modern Electronics Figure
147. n ma nun fay ka i BR n i LEN m a t i nia k P nus j amplifier channel under test via BP3 and BP4 If you are testing both channels of a stereo amplifier simul taneously you would set the switch for both channels to the LOAD posi tion Because the two tester channels are completely independent of each other you can also test an amplifier with only one channel loaded Setting the switch to the UNLOAD ED position routes the signal from the output of the audio amplifier di rectly to binding posts BP and BP2 for driving a speaker This gives you the ability to use your ears as a test instrument during troubleshooting Note that the Stereo Audio Test Box does not require power to oper ate It is completely passive Thus you can use this instrument in the field as well as on a shop testbench Construction Because the circuit is so simple in configuration building the project is Ss ENS SERRE IONS C AR E hy VAM A AMB ut i Fid ail CI gui Ness eR almost as simple The first thing you must do is get together all the compo nents that make up the Stereo Audio Test Box circuitry Next select an en closure that will comfortably house the two large high power resistors and has adequate front and rear pan el space on which to mount the bind ing posts and switches The enclosure you choose must have one perforated panel to permit the heat from the resistors during test
148. n present cellular models and also less expensive The phones will have a sleep mode when not in use to minimize battery drain Among services to be offered are traditional two way communications a less expensive one way outgoing service that responds to a built in pager for incoming calls and an economical one way outgoing only service UNFAIR BANNING Starting January 1 1991 the Government Ethics Reform Act of 1989 Section 601 of P L 102 194 prohibits civil servants from accepting payment for writing or giving speeches about any subject whether or not it s related to their job Apparently directed against congressmen and government officials from accepting honoraria the legislation is written so that it blankets all federal workers As a result it will be illegal for a clerk working for the government to write a poem and be paid for it or a short story or a technical article for a magazine Or writing for a religious newsletter on a part time basis and SO on Clearly the law has to be refined and quickly since it affects people whose part time efforts have nothing to do with influence peddling WRITE TO YOUR CONGRESSMEN AND SENATORS to demand a change in the law There s Senate legislation afoot to ban the use of lead solder for connecting components Bill S 2637 The Environmental Protection Agency can make an exception for certain products but there s no assurance that the electronics industry will be among them As you kn
149. nd 27512 A sec ond emulator can be interfaced with the first to expand the total system to six pods With the 3 Pod Emulator all vou need dois connect the pods in stead of the EPROMSs and inject your prcgram Should modification be ne cessary you simply press a switch to modify your program Having com pleted the emulation you copy the program into EPROM Using the Emulator one can exe cute a split join update and check sum The unit is compatible for bina ry ASCII Intel and Motorola sys tems It is also possible to select ad dresses Features include multiple window software with mouse com mand line or batch file execution split and merge of even odd files calculation and file checksum large files split on three pods pod contents ful page edition data transfer check and copy of single file on working file Deoxidizing Agent Caig Laboratories Escondido CA Cramolin DeOxidizer is said to bea fast acting solution that cleans pre serves lubricates and improves con ductivity of all metal surfaces in cluding gold In use DeOxidizer is sprayed onto metal contacts connec tors and other metal surfaces to quickly remove resistive oxides and form a protective molecular layer that adheres to the metal surfaces and maintains maximum electrical conductivity reduces wear and pro tects the surface from future oxida tion It is for use on switches poten tiometers relay contacts plugs Sockets pri
150. nd binding posts or banana jacks in their respec tive holes The LED mounts on the front pan el Linethe hole you drilled for it with a small rubber grommet to serve as the mounting medium Alternative ly you can use a standard LED panel clip to aid in mounting this POWER on indicator If you use neither mounting device and the LED does not hold in place by friction use a small daub of fast setting clear epoxy cement to secure it in place When wiring the circuit take par ticular care with the sections in which potentially lethal 117 volt ac line power is present Make sure every thing in these sections is fully insu lated and that all connections are electrically and mechanically secure before soldering them Use No 18 or larger gauge stranded hookup wire for the connection between S the coil of the relay and the power transformer Also use No 18 or larger stranded wire to make the connections from the power transformer to the bridge rectifier assembly which should be mounted on the six lug terminal strip Use wire of the same gauge to interconnect the bridge rectifier re lay contacts C and C4 Mount resistors R and R2 on the six lug terminal strip Then use No 22 or larger gauge stranded hookup wire for wiring to the LED Crimp and solder one lead of R15 to the lead of the LED Clip the other lead of the LED toa length of 4 inch and forma small hook in the remaining stub Slide a 1 inch length
151. nd high Q and they are very cost competitive with other magnetic materials The ability to manufacture ferrite materials into almost any shape or configuration offers unmatched flexibility to the circuit designer Ferrite magnetic materials are available in many shapes including various configurations of pot cores laminations that resemble those used in conventional iron core transform ers and toroids Because the simple pot core is one of the easiest types of ferrite forms to wind and assemble this particular configuration is the one recommended in this article for making power transformers for dc to dc converter circuits Even so the design information presented here can also be used for other types of magnetic cores as well A pot core is depicted in the Fig 2 drawing It is simply a cylindrical as sembly composed of two identical halves It is designed so that a plastic bobbin can be installed between the halves When the pot core halves are meshed together the assembly be Say You Saw It In Modern Electronics comes a self shielding closed loop magnetic component An inductor can be fabricated by winding a continuous series of turns on the plastic bobbin To fabricate a transformer you simply wind two or more inductors on the bobbin Pot cores are specified by nominal size in millimeters mm which is us ually part of the catalog number of the product For example a core with a diameter of 22 mm and an as
152. necting the speakers to the Stereo Audio Test Box If you do the amplifier can overload and either shut down or the output transistors will be damaged Other audio components that do not require a load can be connected to the AMPLIFIER INPUT binding posts for testing purposes In this case always leave the switches in the UNLOAD position and connect any instruments used to make tests via the SPEAKER OUTPUT binding posts 37 00 S83 LOAD LEFT SPEAKER AMP IN RIGHT Fur if i C VER R SPEAKER LOAD RIGHT TOURS Es d 4 d SPEAKER dee be a j and Speaker binding posts and switches November 1990 MODERN ELECTRONICS 39 Project By George F Stockman IV se of a desktop computer in non traditional applications offers a fascinating area for experimenting If this interests you our AC Interface circuit is just the ticket for getting you started It pro vides an interesting twist to your workstation by allowing you to load a BASIC program to on off control different electrically operated de vices directly from your keyboard Connecting the Interface to the parallel port on an IBM PC or com patible computer permits up to eight ac powered receptacles to be switched on and off individually or simuitane ously with the touch of a few keys This can be convenient for operating lights fans small motors and other ac operated devices The power drawn by the controlled devices to
153. ng telephone calls often to numbers that require you to dial an area code first At the very least this entails dialing three extra digits before you even get to the ex change and number for the party to be called If you live in a metropoli tan area where the number of tele phone instruments are stretching Ma Bell s capacity to the limit you also have to dial 1 before dialing the area code And to further complicate mat ters if your company requires you to dial 9 just to get an outside line you have to dial yet another digit So you may have to dial as many as five extra digits for each call you make outside your calling district Our Area Code Speed Dialer al lows you to simply press one button toinitiate an automatic sequence that dials the extra digits required in a toll call to one specific area code It can handle up to 10 digits The Speed Dialer is programmed for a spe cific area code sequence If you fre quently call several different area codes you can build a separate Speed Dialer with its own button and pro gram it for one touch dialing of each f you re like me you spend a About the Circuit This project requires a telephone in strument that uses a TCM 5087 or TP 5087 chip for generating the Touch Tone signals required for a SP Sa a a ee 0o 135 DTMF dual tone multi frequency dialing This chip is popularly used in most standard tone dialing tele phones It i
154. ns of fine wire are used the total resistance of the winding can become an appreciable part of the circuit and will affect the voltage regulation and efficiency of the transformer Figure 4 is a simpli fied diagram that illustrates the ef fect of the winding resistance Consider the transformer in Fig 4 to be a perfect component with zero primary and zero secondary resis tance External resistances R and R can be considered to be equal to the measured resistance of the windings of the actual transformer One can easily see that voltages will be dropped across both resis tances E and E in accordance with Ohm s law when the trans former is delivering current Thus the voltage seen by the primary of the transformer is equal to the power source voltage minus E Similarly the voltage seen by the load ts equal a Fable 1 Wire Current Capacity amp Resistance Wire Size Capacity Resistance AWG mA Ohms ft 18 3 250 0 006 at 2 050 0 010 EFi 2B80 0 016 24 ROR 0 026 2 506 0 041 AS 313 0 065 j 200 0 104 32 28 0 162 34 T9 0 261 36 s 0 415 iR 32 0 648 A 9 1 080 z I3 1 660 Say You Saw It In Modern Electronics to the transformer secondary in duced voltage minus E When designing transformers that have appreciable winding resis tances these voltage drops must be taken into consideration Should an initial transformer design exhibit winding resistance that would result in
155. ntact measurements the infrared thermometer cannot be beat The IRTA Thermometer acces sory plugs into the inputs of a hand held DVM or DMM set to dc volts so no enclosure is required Except for the probe assembly all components including switches and battery mount on a printed circuit board EC REMEDIES I ee WINS E UCOLENIE OIM eee a ee P WE About the Circuit The complete schematic diagram of the IRTA Accessory is shown in Fig 1 The output of thermopile detector IRSI is connected to the noninvert ing input of C7 With a 1 000 ohm value for RZ and 150 000 ohm value for R2 ICI amplifies the out put of RSI by 151 1 150 This amplified output is connected to R3 which forms one leg of the summing amplifier The other input to this summing amplifier comes from C2 which provides the temperature compensation voltage for the circuit Actual design of the temperature compensation circuit is a bit involved mathematically and will not be pre sented here The goal here is to have the thermopile detector respond only to temperature differences There 24 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com fore either the reference junction must be maintained at a constant temperature or the reference junc tion temperature must be measured and used to compensate the circuit This instrument uses automatic tem perature compensation Temperature measurement of the reference junction of
156. nted circuit edge connec The Logimer 3 Pod Emulator is designed to run on IBM PC and com patible computers equipped with 384K of RAM It features a power switch input to printer connector parallel input output connector The hardware measures 10 x 74 x 14 The accompanying program supports both monochrome and col or monitors The system supports 512K devices and is fully windowed with pull down menus The pods ter minate in 28 pin connectors that plug into standard IC sockets A 9 volt power supply is included 1 499 CIRCLE NO 59 ON FREE INFORMATION CARD tors and more The product comes in an aerosol can and uses an ozone safe propellant CIRCLE NO 58 ON FREE INFORMATION CARD b Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 15 NEW PRODUCTS Speech Processing System The MicroDyn II from Voize Dy namics Corp Irvine CA voice in put output system is reported to pro vide voice recognition of 1 00C words of up to 1 000 characters pez word with an accuracy of better than 98 and unlimited text to speech synthe sis It listens to command or data in put and then responds by sending keystrokes via its serial port and text to an on board synthesizer for audio prompting and verification Crea tion editing voice training esting and maintenance are accomplished from a standard MS PC DOS com puter with supplied software The software includes sample vocabu
157. ntrols hardware and as sembly users manual 139 95 a black anodized front panel with printed control designations 15 95 CIRCLE NO 61 ON FREE INFORMATION CARD WWW americanradiohistorv com with 128K of battery backed RAM and 32K of on board EPROM and supports tp to 128K of EPROM It Operates asynchronously with an IBM PC AT 386 and PS 2 or com patible computer via a 25 pin DB 25 connector cable arrangement oper ating at 9 600 baud Word groups can be isolated in separate sab vocabularies within the same master vocabulary By spoken command up to 15 independent sub vocabularies can be accessed at any time from a total of up to 100 sub vo cabularies Miniature phone jacks are provided for a microphone and speaker The system supports a wide range of dynamic electret and cardi oid microphones available as op tions Power required is 5 volts dc at 185 milliamperes and is obtained from the host computer over the seri al cable MicroDyn II measures 4 x 3 x 1 and weighs 1 Ib CIRCLE NO 50 ON FREE INFORMATION CARD PC Overcoat Pen Planned Products Santa Cruz CA Circuit Werks 3300 overcoat pen in sulates protects and repairs pc boards components and delicate electronics It is used in the same manner as a writing pen The 3300 applies a conformal coating that in sulates against short circuiting arc ing and static discharge as it protects against moisture abrasion chemi cals and ot
158. of heat shrink able or other plastic tubing over the free ends of the wires that are to con Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 35 MWMwWww americanradiohistorv com nect to the LED network Crimp and solder these wires to the other lead of the resistor and lead stub of the LED observe polarity When the connec tions cool slide the tubing over them to completely insulate them and shrink into place Then make the connections between the circuit board assembly Q on the heat sink and potentiometer R7 and mount R12 on the socket for QJ Make the connections between the circuit board assembly and two lug terminal strip for the output binding posts or banana jacks Mount C7 on theterminal strip Then use No 180r larger gauge stranded wire for the in terconnections between the two lug terminal strip meter movements switches and OUTPUT binding posts or banana jacks Install R6 and R74 on S2 Install RI3 on MI The meter movements connect into the circuit via No 18 hookup wire terminated in No 6 terminals Tightly twist together the fine wires in each conductor of the ac line cord and sparingly tin with solder Fig 3 Interior view of completed Power Supply Note that the circuit board as sembly at the lower left is positioned as far as possible from the power supply at the lower right 36 MODERN ELECTRONICS November 1990 Route the free end of the l
159. om but thermally coupled to the heat sink Machine the heat sink to accommodate the socket De burr all drilled holes Then mount Q7 to the heat sink using the ma com pound to assure good heat transfer from the transistor to the heat sink Plan the layout in and on the en closure so that the circuit board as sembly is as far as possible from the power transformer to minimize elec trical noise in this circuitry Mount the transformer in place with 6 32 x inch machine screws nuts and lockwashers sandwiching the moun ting lug of a two lug terminal strip under the nut of one mounting screw Mount C1 and C4 with wire ties and self adhering wire tie saddles Use a 6 32 x inch machine screw and lockwasher to mount the relay in place Then mount a six lug terminal strip near these capacitors Use inch spacers and 4 40 x deburr all Las Way E Fig 2 A close up view of the small circuit board assembly on which the active circuitry is mounted and wired inch machine screws nuts and lock washers to mount the circuit board assembly in the chosen location Mount the heat sink Q assembly near thecircuit board assembly and a two lug terminal strip near this for the wires that will connect to the OUT PUT binding posts or jacks Use the hardware provided with them to mount the meter movements in their respective locations on the front panel of the enclosure Then mount the two switches panel mount potentiometer a
160. ons for one evening projects and keep you on top of what s new Your knowledge of electronics grows continuously You ll benefit from the latest developments and ideas be able to build or repair more on your own have fun and save more money Supplements are sent 4 5 times a year No risk guarantee you pay upon approval T 1 Convenient easy to access information in one comprehensive source facturer s brochures The sturdy three ring binder with index tabs organizes the material so that you ll find what you need quickly Free circuit layouts on acetate save time and improve results PRE TESTED The hardest part of many elec 1 tronics jobs is in the planning because drawing your own Ne The Modern circuit layouts can be time con tronics ieme suming and inaccurate The Elec man incon Modern Electronics Manual pro vides clear acetate circuit layouts for every project Just place the layout over a photosensitive cop per circuit board expose it to light and etch your own printed circuit Then attach the com ponents plug it in and use it FREE Circuit Layouts on Acetate Manual wt T i gan Michi ATTULIT IH PY ep ULL MONEYBACK GUARANTEE There s no risk in trying The Modern Electronics Manual to see if it s right for you If you are not delighted simply return the please send me The Modern Electronics Manual I understand that if
161. ore required bulky heavy power transformers to provide isolation from the ac line and to step up or down the line voltage as needed Modern gear still uses power trans formers of course but with the new technology the transformers are now far smaller and less costly than their predecessors thanks to driving frequencies that are many times that of the 60 Hz ac line Smaller trans former and higher driving frequency combined with a a sophisticated swit ching technique result in less bulky i 5Y DC INPUT lighter weight more efficient and less expensive equipment Much of the credit for the ad vances in electromagnetics is owed to the development of new magnetic materials particularly ferrites A di rect result of this progress is the dc to dc converter a circuit that enables a dc source of one voltage to be changed or converted to another low er or higher voltage Small size high efficiency and low cost have made these a valuable part of any design er s toolbox In this article our focus is on the theory design and fa brication of dc to dc converters Em phasis here is on practicality and on hands on experimenting Ferrite Pot Cores As shown in Fig 1 the dc to dc con E C2 C 2 C C 2 c2 Em verter is a very simple circuit that contains relatively few components The heart of the converter circuit is power transformer 77 which pro vides the required step up or step dow
162. ormat disk of sample pictures ef fective pecket throughput readout screen colors set sound on off switch RS 232 cable and instruc tions The program requires an IBM PC XT AT or compatible with 512K of RAM and CGA EGA or VGA graphics and an MFJ 1278 multi gray level modem The copy protect ed program is distributed on three 5V disks 3 disks are available 59 95 CIRCLE NO 55 ON FREE INFORMATION CARD playing the result as a high resolution frequency Basic sensitivity is rated at 50 mV into 1 megohm for the 100 MHz channels and 25 mV into 50 ohms for the 1 3 GHz channel Self test and the ability to hold a reading are standard features 485 CIRCLE NO 54 ON FREE INFORMATION CARD Updated Desktop Computer Atari s new MC68000 based 32 bit internal 16 bit desktop computer comes with a full megabyte of memory for eight times as many colors 4 096 in all than were possible with the predecessor external 1040STE 1040ST It also features hardware based smooth scrolling and a co processor BLiTTER chip for accel erated graphics speed Upgraded sound architecture in the computer provides digitized pulse code modu lation stereo sound Other features of this upgraded computer include internal 3 5 flop py disk drive 8 MHz operating speed built in MIDI ports built in TOS operating system with GEM desktop industry standard modem and printer ports two analog joy stick DMA hard disk and ROM p
163. orts and two button mouse A software package included with the computer provides spreadsheet word processing educational and enter SS a EE O OSSQ S QE Q QOIS EYE 29 2 22 SSLLLLLLLGLCE SD IXEELLLUSkCRLLAELLO 14 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com Say You Saw It In Modern Electronics tainment programs that utilize the computer s upgraded sound and scrolling capabilities The computer measures 184 XW x 114 D x 224 H and weighs 9 5 lbs 699 95 CIRCLE NO 56 ON FREE INFORMATION CARD Scanner Antenna Antenna Specialists Model MON 53 all band scanner antenna is available for either roof or deck mounting The antenna utilizes an exclusive Mi cro Choke to achieve enhanced performance in the 800 MHz band u wa ua Pom a x without affecting performance at other monitoring frequencies Included with the MON S3 is a 17 foot coaxial cable with an installed pin plug ready for immediate mounting ina 3 hole All band Micro Choke performance is also available with the Antenna Specialists Model MON 52 mobile trunk lid mount and Model MON S8 base station antennas CIRCLE NO 57 ON FREE INFORMATION CARD a jd a s EN es cep is a i Multi Pod EPROM Emulator With Total Power International s Lowell MA Logimer 3 Pod Emu latcr you can emulate up to three EPROMS simultaneously EPROMs tha can be emulated include the 2764 27128 27256 a
164. oseph Desposito If owning a dot matrix or ink jet printer in the 1990s makes you feel like a second class citizen there s something you can do about it LaserT win from Metro Soft ware 1870 W Prince Rd Suite 70 Tuc son AZ 85705 will let most dot matrix and ink jet printers emulate a Hewlett Packard LaserJet Series II printer LaserTwin is a terminate and stay ready TSR utility that translates Laser Jet commands into a language your print er can understand This lets you config ure applications programs for the HP Se ries Il LaserJet rather than for your dot matrix or ink jet printer And since the HP Series II LaserJet enjoys wide sup port among applications that use a varie ty of typefaces and sizes such as Page Maker 3 0 Microsoft Word and Word Perfect 5 1 LaserTwin lets you tap into that support In essence your non laser printer s ca pabilities are extended to increase the number of typefaces it ordinarily is lim ited to permit printing larger sizes and printing in landscape sideways orienta tion Consequently the program can open up desktop publishing opportuni ties for people who do not own or plan to buy a laser printer LaserT win is for the IBM PC and com patible computers It requires at least 2MB of free hard disk space The prod uct which includes three 5 25 inch disks This drawing was done in AutoCad The call out was A and a user manual has a suggested retail price
165. ot punched with the aid of the centering template The hole can be punched slightly undersize and enlarged witha tapered reamer A piece of wood held in a vise provides backup on the inner walls of a project box When making medium to large round holes the waste slug can be made to remain in the plastic elimi nating the need to remove the waste from the tip Push the tip through the plastic without axial rotation The plastic in the clean out slot retains the waste in the panel Use a pencil to push out the slug To lift the waste 600W rotary lamp dimmer 5A Slow blow Chassis mount fuse ac receptacle 117Vac Fig 4 Wiring details for light dimmer and soldering iron circuit with the tip rotate the tool slightly after it penetrates the plastic to cut the material in the clean out slot When machining the panel of a plastic project box cover the entire outer surface of the box with mask ing tape to avoid scratches as you work Mark hole locations on the tape and punch from the outer sur face At correct tip temperature not critical the holes produced are re markably clean At higher heat and with thicker panels a small annular ring may ferm on the entrance and a small burr on the exit sides of the hole Remove burrs using the coun tersink bit or knife These thermal punches are intend ed to be used on plastics up to 4 inch thick Holes were punched in plastics up to J inch thick but su
166. ou tp write into RAMs AOMs and run a 8085 m 249 Sof which uses Bimdar machine language as IBM PC You wat wrrte the ievial ins tructons to tel the 8065 processor 10 get started and store these instructions in permanent memory in a 2816 E PROM Teaches you all about input and output ports computer tmers Build your own keyboard and leam how to scan keyboard and dsplay No previous computer knowledge required Sample pasy to understand mstruction teaches you to writs in maduna language ROBOTICS KIT FOR ABOVE MM 8010 71 95 15 Day Money Back Guarantee 2 Year Warranty Prces subject to change WRITE FOR FREE CATALOG CIRCLE NO 79 ON FREE INFORMATION CARD ig WMWWw americanradiohistorv com Technology How To Thermally Machine Project Boxes Give a professional looking finish to the plastic enclosures in which electronic projects are popularly housed By Adolph A Mangieri QUT achining the popular poly L M vinyl plastic project en closures that have largely replaced costlier phenolic project boxes can be an exercise in frustra tion Though shatterproof these boxes are made from a soft plastic that has a relatively low melting point As a result the bit of a hand drill can tear or melt its way through the plastic and walk excessively from the exact point you want to drill a hole Grabbing action often turns larger size holes into ragged and oval shapes Also making the square and rectangular holes
167. ow the commonly used tin lead ratio for solder is 60 40 and industry spokespeople say that there s no lead free substitute for it when considering corrosion resistance and thermal stress Among alternative alloys is indium based material Again write to your legislators about this Babies don t suck on soldered interconnects Moreover the lead in solder is contained within the compound TRACKING SATELLITE INTERFERENCE Engineers at Georgia Institute of Technology say they ve developed a system for pin pointing the location of ground stations that interfere with satellites Called the Satellite Interference Locations System it uses a variation of techniques long used for radio navigation The system employs a Time Difference of Arrival technique to infer longitude and latitude and could theoretically provide accuracy to within a fraction of a mile Most satellite interference is not caused by a Captain Midnight which interfered with Home Box Office HBO four years ago but due to accidental turn on of a legal transmitter at the wrong time sloppy operation by TV news crews and commercial FM radio station signal leaks into satellite uplinks 6 MODERN ELECTRONICS November 1990 Say You Saw It In Modern Electronics WWW americanradiohistorv com Amateur kadio Buyer s Guides You can buy with confidence when you have all the facts The 1991 Equipment Buyer s Guide gives you in depth coverage of HF VHF UHF rigs and accessories
168. pec tively If not touch the hot probe to pin 8 of C6 and note if you obtain a reading of 9 volts Assuming the outputs of C7 and IC8 are correct touch the hot probe of the meter to pin 7 of the C1 IC2 and JC3 sockets In all three cases you should obtain a reading of T 5 volts You should also obtain a reading of 5 volts at pin 4 of all three sockets If you fail to obtain the proper reading at any point power down the circuit and rectify the prob lem before proceeding Once you obtain the proper read ings at all points mentioned power down the circuit and plug the DIP ICs into their respective sockets Make sure each is properly oriented and that no pins overhang the sockets or fold under between ICs and sockets On power up one of the LEDs should light the specific one that does depending upon the position to which S2 is set Set your meter to its 200 millivolt full scale range Con nect the common lead of the meter to circuit ground and the hot probe to the wiper contact of R16 and ad just this trimmer control for a meter reading of 65 millivolts This done turn off the adapter and set R4 and R20 to about center of rotation Plug the adapter into the banana jacks on your meter and set the meter to its 200 millivolt full scale range Plug the cable from the probe assem bly into its connector on the main cir cuit board assembly and switch on project and meter Setting 2
169. r Spanish CQ and the CQ Amateur Radio Buyer s Guides Say You Saw It In Modern Electronics Mn HM T can t believe how easy it is to build my own electronic devices This book shows me how to do it step by step Newly revised and enlarged now with more than 550 pages shows you how to successfully build and repair electronic appliances and equipment Useful projects easy to follow repair instructions detailed instructions for correctly using test equipment up to date techniques and the latest in electronics know how Dozens of practical money saving projects With detailed assembly instruc tions schematics circuit layouts and parts lists you ll build projects in areas ranging from telecommu nications stereos and computers test and repair tools to radio and TV And you wont spend valuable time searching for parts because our Sources of Electronic Compo nents and Supplies provides you with an updated list of local and mail order suppliers Do it yourself repair techniques Professional hints tips and short cuts will make repair easy and efficient Learn money saving maintenance tricks and repair techniques You ll feel confident about troubleshooting problems You ll know when to call for ser vice and when you can fix equip ment yourself Timely supplements offer you brand new projects and up to date information Experts in their fields work out new and interesting assembly instructi
170. r jagged edges This is caused by the copy protec ton jamming signals em bedded in the video tape such as Macrovision copy protection DIGITAL VIDEO STABILIZER RXii complete ly eliminates all copy protec tions and jamming signals and brings you crystal clear pictures WARNING The Digital Video Stabilizer RXII is in tended for private home use only It is not intended to copy rental movies or copyrighted video tapes that may constitute copyright infringement e em M eee we eee FEATURES Easy to use and a snap to instail The best and the most exciting Video Stabilizer in the market State of the art micro chip technology 100 automatic no need for any troublesome adjust ments e Works on all types of VCRs TVs and Monitors Oe Light weight 8 ounces and Compact 1x3 5x5 Beautiful deluxe gift box e Uses a standard 9 Volt battery which will last 1 2 years Similar units sold else where for 99 or more UNCONDITIONAL 30 DAYS MONEY BACK GUARANTEE FAST UPS DELIVERY Air Shipping available ee eee t r a ToOrder 1 800 445 9285 or 516 568 9850 49 95 ea S 4torp amp n Visa M C COD M F 9 6 SCO Electronics Inc Dept CME11 581 W Merrick Rd Valley Stream NY 11580 battery not included CIRCLE NO 90 ON FREE INFORMATION CARD FREE ONE YEAR SUBSCRIPTION Keep abreast of
171. rical adjustments and power supplies Interspersed among these is a chapter ti tled Remove and Replace which gives hints on how to go about sensibly disas sembling the camcorder to remove and replace items that have gone bad Near the end of the book is an extensive Trou bleshooting chapter that deals with this topic in a symptom and solution ap proach Though many of the solutions presented here are specific to certain brands models of camcorders it is appli cable to other brands models The book closes with three appendices commonly used abbreviations camcorder manu facturers with addresses and a glossary of technical terms This well written and easy to under stand book is exceptionally well illus trated Throughout the text are excellent photos schematic and block diagrams tables and drawings that help explain the text material so that the reader can readi ly navigate among the various elements that make up the camcorder If you do camcorder repairs you need this book CMOS TTL Digital System Design By James Buchanan Published by Mc Graw Hill Publishing Co Hard cover 258 pages 44 95 This book is about electrical design of high speed TTL and CMOS systems It is not about logic design and should not be considered as a course in logic circuit de sign theory Its main thrust is showing how TTL and CMOS devices must be im plemented to behave properly and how to optimize the environment in which they are us
172. ring installation Set tings for this and other features can be changed by running the install program again typing LTINSTAL instead of FIRSTIME When residing in memory LaserTwin takes up 26K of RAM There is no provi sion for moving the program into LIM 4 0 expanded memory Once you load the program into mem ory youcan forget about it It runsin the background and is completely transpar ent However if you want to change cer tain program settings you must issue commands from the DOS prompt For example the command LT K reduces the size of the printout Weran a test pattern included with the program Three things were obvious from the test printout First the Juki dot matrix printer could indeed function just like an HP Series II printer second the printer was printing very slowly and third the quality of print from the nine pin printer was nothing likethat obtained from a laserjet printer We then set up Microsoft Windows 3 0 to work with an HP Series II printer with 4 MB of memory LaserT win lets you do this if you have an extra 4 MB of free space on your hard disk There is one other step you haveto perform with Win dows you have to edit the WIN INI file pem Fer a Eoi ag he I 4 M cs TEE n ax a UE s E 2 mr erm mm Bf C Fig 1 Samples of printouts using LaserTwin A HP Desk Jet B 24 pin dot matrixand C 9 pin dot matrix printers 68 MODERN ELE
173. rity Cameras Personal Protec tion Books More Huge catalog 5 00 Re fundable PROTECTOR P O Box 520294 B Salt Lake City UT 84152 MINIATURE Electronics like James Bond Catalog 4 00 refundable F amp P Enterprises Box 51272 Palo Alto CA 94303 H WANTED OLD Antique Radios and TV s Pre 1950 Any Condition Repair Same Old Tubes For Sale Thrifty TV 11 E Marie St Hicksville NY 11801 516 822 4501 70 WATT Audio Amplifier Simple and easy to build Plans 4 00 T J L Enterprises 1902 Ridge Rd Suite 302ME West Seneca NY 14224 CALLER ID Lets you know the person call ing you before the telephone is picked up CBR Box 212 Rochelle Park NJ 07662 50W Subwoofer Add awesome bass to your home stereo system This is an excellent per forming component not cheap junk Com plete plans 18 00 C Rotthoff Box 70 Atlanta GA 30274 BUILD an Infrared Motion Detector Ultrasonic Distance Meter Long Range In frared Transceiver Complete plans 4 00 each Free Catalog K Kemp 13772 Golden west St 549 Westminster CA 92683 FREE CATALOG Save hundreds on sought after electronic electro mechanical and com puter related hardware and components including hard to find items Call toll free 1 800 776 3700 American Design Com ponents Dept 112 110 815 Fairview Avenue Fairview NJ 07022 COMPUTERS EQUIPMENT assortment Electronic com puter test descrambler Catalog 3 00 Re
174. rrection Lithium Kickstarter and Improved PROM and SPROM Chips By Joseph Desposito In this month s column we highlight three new error correction and detection chips for high performance memory sys tems Following that is a tutorial on pari ty checking versus Hamming code error detection and correction We then cover a lithium kickstarter chip for personal computers Finally we examine two up graded PROMs 32 Bit Flow Thru EDC Integrated Device Technology 3236 Scott Blvd P O Box 58015 Santa Clara CA 95052 has introduced a 32 bit flow through error detection and cor rection EDC unit the IDT49C465 that achieves fast speeds by using a flow through two bus architecture The two bus architecture eliminates several exter nal memory drivers allowing a simulta neous data error detection and correction process to occur between the processor and memory Operating at 20 ns error correct time the IDT49C465 provides designers with speed and reliability for high performance memory systems The parity check and generate fea tures on the IDT49C465 can be used with any 32 bit RISC high performance mi croprocessor to maintain parity on the system bus and eliminate five external components In addition sophisticated diagnostics on the component can log up to 16 errors and capture the most recent erroneous data word giving designers greater flexibility in handling data errors As microprocessor speeds
175. rtain that the connections for the electro lytic capacitors are properly polar ized and follow the basing configu rations shown for the transistors Strip inch of insulation from 46 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com both ends of as many 6 inch lengths of stranded hookup wire as are need ed for the connections to the transis tors that serve as electronic switches for the keypad The number of wires needed is determined by the number of transistors used as detailed above Tightly twist together the conductors at both ends of each wire and tin with solder Connect and solder one end of these wires to the emitters and collec tors of the transistors Do not termi nate the other ends at the keypad of the telephone instrument just yet Connect ard solder the red and black insulated leads of a 9 volt bat tery snap connector to the positive and negative rails respec tively onthecircuit board assembly Prepare three 10 inch long strand ed hookup wires as above Crimp and solder one end of each of two of these wires to the lugs of 57 Termi nate the other ends of these wires at the appropriate points on the circuit board assembly Connect and solder one end of the remaining wire to a point in the circuit that is at ground potential Double check all wiring Make sure each component is in its correct location and is properly oriented where applicable Check your solder
176. s CHy se tag Zip Send only 4 95 each today Foreign 6 U S funds L1 Check O Money Order O MasterCard O VISA O Amex Card No Expires Signature 0 required on all charge orders Mail to CQ Communications inc 76 North Broadway Hicksville NY 11801 FAX 516 681 2926 wWwmr americanradtehtistorv com Parts XPress 340 E FIRST ST DAYTON OHIO 45402 IDLER TIRE KIT This popular kit contains 170 of the most popular idler tires 10 each of 17 different size save d money by having the right tire in stock Also included is a comprehen sive cross reference listing over 80 manu facturers assembly numbers and over 200 model numbers All tires are available individually for reorder 495 MM 400 900 VCR REPAIR PARTS KIT With this convenient kit you can do most of m your VCR repair jobs A the same oo wn ftdt ears Ove pRO pans for RCA Hitachi SA Sanyo Lloyds Panasonic Sony All parts are available individually for reorder _ MM 400 950 8995 VCR SPRING ASSMT A wide assortment of springs usedi manyn brand V Clutch springs idler springs tension springs etc 11 tension springs and 5 pressure Springs 48MM 430 300 1 VCR WASHER ASSMT A wide assortment of plastic washer used in clutch ass mblies and idlers 150 pieces split ring and regular
177. s first converted into its digital R4 140K ire 1 Viw Cz equivalent by means of an analog to dig ital A D converter The two digital numbers are then presented to a micro processor that has been programmed to divide one number by the other Finally the quotient is converted back into its analog equivalent with a digital to ana log D A converter There is a simpler way to accomplish this task Indeed all analog and digital functions and operations described above can be replaced by a single inte grated circuit known as an analog divid er A digital designer might point out that Vour Vig CA vue Fig 2 Example of an operational amplifier summing adding circuit Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 57 ELECTRONICS NOTEBOOK Vin C1 UM et RY 3 2 tov LOK VouT Vin 2 EE C Fig 3 Example of an operational amplifier differencing subtracting circuit the digital circuit provides a considerably more accurate quotient when it divides two numbers True but in this case the numbers come from a pair of A D con version circuits Therefore overall accu racy of both circuits is controlled by ana log circuitry Shortly we ll experiment with the 10v Fig 4 Schematic of a simple logarithmic amplifier DIV100 a sophisticated analog divider chip First however let s look at the bas ic principl
178. s for equipment are simplified because isola tion and confinement of the ac voltage re duces shock and fire hazards When equipment power is off a pushbutton closure is detected by the chip see Fig 2 which then sources a minute amount of lithium energy This energy lights an opti cal isolator to kick on a triac that in turn powers up the system Alternatively the pushbutton can be wire ORed to a signal from a real time clock or a telephone ringer the equip ment can then be automatically turned on The chip monitors a second pushbut ton to reset a processor when the operator wants to intervene This interface allows for easy hookup of an external switch for a hardware reset function Along with lithium kickstarting the Be anFCC LAN EEEGTHORK TECHNICIAN EC a Era pa Earn up to tamg O f 30 an hour Hees j and more glean at home in spare time P a No previous experience needed No AS SEG No commuting to class The Original Home Study course prepares you for the FCC Commercial Radio telephone License This valuable license is your professional ticket to thousands of exciting jobs in Communications Radio TV Microwave Maritime Radar Avionics and more even start your own business You don t need a college degree to qualify but you do need an FCC License No Need to Quit Your Job or Go To School This proven course is easy fast and low cost GUARANTEED P
179. s to escape If you cannot find such an enclosure use a standard metal project box but replace a solid metal panel with a perforated panel like those used for radiator covers which you can purchase from most hardware and housewares stores Having obtained a suitable enclo sure plan its panel and interior lay out in a logical manner The best place to mount the two resistors is on the floor of the enclosure as shown in Fig 2 All binding posts that per mit connection to test instruments Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 37 WM NN americanradiriehistorv com Circuitry for single channel two identical circuits are required for stereo testings BP Io NOTE RED Speaker output ABLK i P20 Br3o BLK m T O R1 Amplifier 1 input P LOAD u UNLOAD 100W RED BP40 RED s OBP5 BLK RED o BP6 To oscilloscope meter auxiliary device BLK Dr BP8 Fig 1 Schematic diagram of one channel two identical channels are required for stereo of the circuitry used in the should be grouped together prefer ably on the rear panel of the enclo sure as shown in Fig 3 A The re maining binding posts and switches should also be grouped together in separate left and right channel PARTS LIST BP1 BP4 BP6 BP8 Red five way binding post BP2 BP3 BPS BP7 Black five way binding post R1 8 ohm 100 watt noninductive power resi
180. s today 800 662 6836 TEST YOUR ICQ Integrated Circuit Quotient A B B Bob Noy C Wilber X FOFLA4C9A cor S ET Messa o7 RL yor t 7 CE J a SASS RR S d i VG ad P Available February 1991 Add sales tax in NY MA IL CA k Hearst Business oi REESE Send check 2 er Ave Garden City NY 11530 with PO to Att Marie Botta Say You Saw It In Modern Electronics Which two inventors similar plans f battled for Vu DX artles amp James ce and Jack Kilby and Orville Wright If you answered B vou re already ahead of the game To stay ahead of fast changing IC product specs and vendor information smart electronic professionals will turn to the ALL NEW 1991 IC MASTER 3 Volumes 3 400 pages Functional guide to 80 000 standard ICs including 12 000 i NEW ICs 1 000 manufacturers data pages Pre paid orders received Before Jan 31 91 135 After Jan 31 91 160 516 227 1300 FAX 5164 227 1901 CIRCLE NO 86 ON FREE INFORMATION CARD developed st ICs and over its patent Powerful little 12 Vdc no load Clairex CLM 6000 LED photoconductor U shaped package with WMW americanradiohistorv com QUALITY PARTS DISCOUNT PRICES FAST SHIPPING Gi eal aii P O Box 567 Van Nuys CA 91408 12 VDC GEAR MOTOR Soho GBL 35 DH 210
181. s wired to a keypad ina matrix format made up of vertical columns and horizontal rows The dialing chip and keypad hookups are shown in the boxed section in Fig 1 When no key on the dialing keypad is pressed pull up resistors are active on column inputs and pull down re sistors are active on row inputs Col umn latches are on and ready to store column key closures After a key is pressed the row pull down resistors cause a negative true condition to ex ist on the column inputs which starts an oscillator and initiates tone gener ation In this project transistors se quenced by a decade counter close 44 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com the appropriate keyboard switches by electronic means CMOS 555 timer C in Fig 1 is configured as an astable multivibra tor Its square wave output at pin 3 goes to INPUT pin 14 of 4017 decade counter C2 Each time pin 14 sees a pulse C2 decodes it and delivers a high on one of its 10 output pins Only one output pin is high at any given time all otner pins remain low When activated the outputs at pins 3 4 10 5 and 9 of C2 are for ward bias Q3 through Q7 respec tively The transistor emitters and collectors connect to the row and col umn inputs of the keypad in the proper sequence for the particular area code for which the project is built The other outputs shown for Say You Saw It In Modern Electronics Cn i cs SSS SE SS e
182. side the cir cuit board assembly and proceed to machining the enclosure that will house he project You can use any type of enclosure in which to house the project that is large enough to accommodate the full size circuit board assembly and has room on its top panel for mount ing the ac receptacles and at one end to accommodate DB 25 connector Pl This can be all metal all plastic as shownin the photos or a mixture of thetwo Machine the enclosure as needed That is drill mounting holes in the floor for the circuit board assembly cut a suitable size and shape slot through one end wall in which to mount the DB 25 connector and drill a hole through the opposite end wall for entry of the line cord Final ly cut as many slots in the top panel into whick to mount the number of ac receptacles being used If you drilled any holes or cut any slots through a metal panel deburr the edges to remove sharp projections and line the ac cord s hole with a rub ber grommet Now mount the receptacles in their slots and the circuit board assembly in place using 2 inch spacers and 4 40 x 34 inch machine screws nuts and lockwashers If the line cord en try hole is through metal line the hole with a rubber grommet Passthe free end of the line cord through its hole and tie a strain relieving knot in it about 6 inches from the free end in side the enclosure Tightly twist to gether the fine wires in each conduc tor and sparingly t
183. ss shaft extender V4 brass shaft coupler V4 shaft collars 4 V4 diameter spacers 1 long with 4 hole TV rabbit ears antenna four sections AA and AAA alkaline or Ni Cd cell shells Brass or aluminum spacer or hub 4 long 14 hole Miniature and subminiature r f trans former shield cases Medium sewing needle Plastic handle see text Light gauge sheet aluminum 40 watt soldering iron with 4 tip Weller Model SP40 or equivalent Solid state incandescent lamp dimmer Ac line cord with plug Small enclosure Chassis mount ac receptacle 5 ampere 3AG fast blow fuse and holder n the file tang on the grinding wheel Slide the tip firmly onto the tang and pinch peen and shape it until a rectangle is formed Because the hard brass tubing 1s not highly malleable the rectangle may end up being slight ly barrelled Lastly cut a clean out slot in the tip as shown The beveled chisel knife cutter shown at top center in Fig 1 handily forms large cutouts As an example in making chisel knives cut off a 14 inch length of inch tubing Pinch one end flat for 4 inch in a vise to ob tain a double thickness flat blade One or both vertical edges of the flattened portion will probably split Select the best side of the flat blade for the knife and remove the other side leaving a single thickness blade Do this by scoring the blade 7 inch from the end with a fine triangular file and pry off the wa
184. ssorted sizes installed on adapters that have a 4 inch diame ter upper portion The adapters fit into and are retained by a inch brass shaft extender shown at top left in Fig 1 The shaft extender re places the the original soldering tip and butts firmly against the barrel of the iron It transfers axial punching force to the barrel of the iron not to the inner end of the heating element November 1990 You may need to cut the shaft of the extender so that it does not bottom out against the inner end of the heat ing element In lieu of a shaft extender you can make one by installing a 1 4 inch length of brass shaft on a V inch shaft coupler Drill a small spot on the shaft to firmly seat the setscrew Lacking a shaft coupler make one from a inch long by inch di ameter brass hub with a 4 inch hole You may have to install one or two 6 32setscrewsinashaft hub salvaged from a pulley or gear Figure 1 also shows a chisel knife tip at top center a rectangular tip at top right and a clean out tool at bottom When making the adapters shown in Fig 1 avoid high precision tight fits because metal oxidation and thermal expansion may create prob lems with freezing or binding Be aware though that a very loose fit impairs heat transfer Dimensions specified are nominal and should be altered as needed to match the sizes of brass tubing you are using Use only brass or aluminum for the adap ters but
185. ste portion Use a file to true up the blade and bevelit on one side to a knife edge Assorted tool guides or templates and a panel machined with these tools is shown in Fig 3 Use light gauge aluminum sheet to make tem plates Lay out and drill the holes slightly undersize and ream to final size to clear the tip Scribe cross hair lines Make the DB9 connector tem plate shown at top left in Fig 3 by drilling a number of small holes and filing the hole to final size Metal frames of miniature and standard slide switches and other components serve well as tooling templates You need a means to adjust the voltage applied to the soldering iron used with your home fabricated tools I use a bench powerstat vari able voltage transformer with cali brated dial It has two ac receptacles which permit operation of two hot punch irons at the same time You can use a full range solid state traic motor speed controller instead An inexpensive wall mount solid state rotary incandescent light dimmer that handles loads up to 600 watts performs just as well Wire together the dimmer and iron as shown in Fig 4 Install the dimmer in a small enclosure and calibrate its dial in 10 volt steps from 60 volts to maximum To calibrate connect a 60 watt incandescent lamp and an ac voltmeter preferably true rms vxot peak type to the load side of the dimmer Using the Tools Like in soldering the technique used to machine
186. stor MCM Electronics Cat No J 28 048 or similar S1 10 ampere dpdt toggle switch All Electronics Cat No MTS 8HD or similar Misc Suitable enclosure 6 x 5 x 3 aluminum or steel with perforated cover see text 4 adhesive backed tie mounts plastic cable ties quick disconnect insulated terminals let tering kit see text 14 gauge strand ed wire solder etc Double up on these components for stereo version of project Parts Supplier Addresses All Electronics Corp P O Box 567 Van Nuys CA 91408 1 800 826 5432 MCM Electronics 650 Congress Park Dr Centerville OH 45459 4072 1 800 543 4330 Stereo Audio Test box groupings on the front panel as shown in Fig 3 B Once you know how you want the switches binding posts and resistors tolay out drill mounting holes for all but the resistors Deburr all holes to remove sharp edges Then label each banana jack hole position according to its function and each switch posi tion Use a dry transfer lettering kit for a professional appearance pro tecting the legends with two or more light coats of clear acrylic spray AI low each coat to dry before spraying on the next Alternatively you can use a plastic tape labeler or even masking tape labels Mount the binding posts in their respective locations use red colored ones for BP1 BP4 BP6 and BP8 and red colored ones for the remaining binding posts so that you know the polarities of the hoo
187. storv com Youcan use the brass or aluminum outer finetuning shaft of rotary type TV tuner switches to make the spac ers Make the spacers long enough to butt firmly between the top surface of thecutter and the front edge of the shaft extender Carefully square up both ends of the spacer to assure good thermal contact Use the brass shield of a submina ture r f transformer to make the inch square cutter Use the shield of a miniature r f transformer to make a inch square cutter shown un mounted at the right in Fig 2 Bevel the inside edge of the tips to a knife edge with a small fine flat file Clean out slots are optional on these cutters because you can easily pry out the waste slug with a clean out tool made from the plastic handle of a tooth brush and a medium size sewing nee dle Drill a small holein the end of the handle and secure the the needle in place epoxy cement The tip shown at the top right in Fig 1 has a rectangular cutting edge for roughing in the slots of slide switches To make square and rec tangular tips prepare and sharpen the end of the tip but defer slotting of the clean out slot Usethesquare and rectangular tapered tangs of files asa forming mandrel If needed true up Say You Saw It In Modern Electronics tee pr ETT uum aR EE o e mc LA CH cU CONI E LECCE Eu o EE X c tc c ac P MEUS NN UN CN ES Rm S RR RR rH NN e CNN MATERIALS LIST 4 diameter brass or aluminum shafts V4 bra
188. t age checks and are satisfied that the circuit is properly wired Next mount the banana plugs in their respective Say You Saw It In Modern Electronics NOTE P1 and P2 mount on trace side of board locations on the copper trace side of the board After they are physically mounted spot solder the banana plugs to the copper pads surrounding them to assure good electrical con nections Now install and solder into place the resistors trimmer controls capa citors diode and LEDs in their re spective locations Make sure the electrolytic capacitors diode and LEDs are properly oriented before soldering their leads into place Continue populating the board by installing and soldering into place IC7 IC8 and C9 making sure you follow the basing diagrams given in Fig 1 Trim the leads of a 9 volt bat tery snap connector to a convenient length and strip 4 inch of insulation from each Tightly twist together the exposed fine wires and sparingly tin them with solder Plug the black in sulated lead into the hole labeled B1 Fig 3 Wiring guide for main pc board and solder it into place Similarly plug the red insulated lead into the hole labeled B1 and solder it into place Mount a 9 volt battery clip holder in the space reserved for it at the top of the circuit board assembly with 4 40 machine hardware Final ly mount theswitches in their respec tive locations If you wish you can mount a cable connector in t
189. t Growing Field Of High Tech Electronics CIE Gives You The Training You Need to Succeed re g f you re anxious to get ahead and build a rea 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 ClE s job oriented programs offer you the quickest possible path to the career of your dreams And CIE also 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 star
190. tage of the Fig 1 cir cuit is that the value of filter capaci tor C3 can be many times smaller than is required by a conventional power supply driven from a 60 Hz source This is because higher fre quencies are more readily smoothed with smaller values of filtering capa citance A smaller value capacitance results in a physically smaller capaci tor Thus size weight and cost are all reduced It is important to note that in a cir cuit of the configuration shown in November 1990 MODERN ELECTRONICS 49 m M JAA n i amaereamnradiohistorv com pi c a Ww Oo a 4x8 18X11 26X16 36X22 CORE SIZE mm Fig 3 Pot core selection nomograph Fig 1 using an ungapped core full wave rectification of the output waveform should always be used This is because the net value of dc current in the windings of the trans former must be zero to prevent satu ration of the core due to direct cur rent Half wave rectification would not satisfy this requirement and thus should not be used Transformer Design Considerations Although the dc to dc converter cir cuit operates with square waves the transformer design technique is very much similar to that used for sine wave excitation It is important that the following be fully understood if you expect to design and make a use ful transformer Ferrite products manufactured to day are available in many different compositions Select
191. tal multimeters 58F 302F a AC Current Meter Decade Biox M infrared emitter splitter sensor and remote power supply modules The system utilizes standard four con z ST 10t0 9610 or COMPUTERS WITH THIS KIT ductor telephone cabling and con 69 95 FEF 9620 dm INCLUDES All Parts Assembly and Lesson Manual xz enm 1 m i del nectors to reduce cost and simplify EU 1000 Amps viti ra ah eis Ive digit LCD LEARN TO BUILD AND PROGRAM Murs Data 5 Peak hold 47 ohm to 1M amp 100K pol 9620 Capacnor Biox 47of 10 10MFD 129 00 Fully regulaled and short ircui protected XP 575 without meters 39 95 installation The sensor and emitter mount in Digital Triple Power Supply XP 765 standard light switch junction boxes They utilize a specially formulated Lexan lens that passes only IR signals while rejecting all other wavelengths 249 0 20V at 1A 0 20V at 1A Fuly regulated Short circun protected wih 2 limit control 3 separate suppiles XP 660 with Anaiog Meters 175 10 Max IL Res 7 Tax Sine Square Triangle Pulse Ramp 2 to 2MHz Freq Counter 1 10MHz GF 8015 without Freq Meter 179 WE WILL NOT BE UNDERSOLD C amp S SALES INC UPS Shipping 48 States 5 A s 1245 Rosewood Deerfield IL 60015 800 292 7711 708 541 0710 GF 8016 Function Generator with Freq Counter Startng from scratch you bulk a complete system Our Micro Master trainer teaches y
192. tants they do and don t get along with Then it s off to the operating room The operation is performed by us ing the mouse to grab the desired instru ment or medication and then using it Performing the operation is realistic enough that if you re really squeamish like I am it s difficult to make a cut with IE M ACIE Qm m NN EE a CDM a u ccn l NEN OV x 7 JA M m Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 65 PC CAPERS the scalpel And unfortunately while the procedure is described in the accom panying textbook there are no pic tures in the abridged version I lost quite a few patients before I figured out what some of the parts were You can also lose your patient by forgetting to clamp off bleeders those arteries and veins you cut through As the body count piles up you eventu ally even get to save a patient or two But it is distracting to hunt around on the lit tle table for what you need while your pa tient is bleeding to death on the operating table Now I know why doctors in medi cal shows are always yelling things like retractor clamp and spanner wrench Once you take your eyes off the patient it s easy to forget just where you were in the operation You can however put the operation on hold by pressing the P key on the comput
193. ted with core lessons applicable to a areas of electronics As advance CIE makes job opportunities available to you through the bimonthly school paper The Electron At Your Own Pace amp In Your Own Home 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 amp 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 eams 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
194. terface and BASIC program let you control lights and appliances from the keyboard of your IBM type computer By George F Stockman IV Area Code Speed Dialer Automatically dials any area code including the 1 that may be required and any digit needed in an office telephone system to access an outside line By Dave Wysock DC to DC Converters Designing and building circuits to convert one dc voltage to another By Anthony J Caristi COLUMNS Electronics Notebook Analog Arithmetic By Forrest M Mims III Solid State Devices Error Detection amp Correction Lithium Kickstarter and Improved PROM and SPROM Chips By Joseph Desposito PC Capers Life amp Death and The MousePen By Ted Needleman Software Focus Metro Software s LaserTwin Lets Dot Matrix Printers Emulate Laser Printers By Joseph Desposito DEPARTMENTS Modern Electronics News Editorial Modern Electronic Drafting By Art Salsberg Letters New Products Books amp Literature Advertisers Index 4 MODERN ELECTRONICS November 1990 www americanradiohistorv com EDITORIAL STAFF Art Salsberg Editor in Chief Alexander W Burawa Managing Editor Dorothy Kehrwieder Production Manager Elizabeth Ryan Art Director Barbara Terzo Artist Pat Le Blanc Florence V Martin Phototypographers Hal Keith Illustrator Bruce Morgan Photographer Joe Desposito Forrest Mims III Ted Needleman Contributing Editors BUSINESS STAFF
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196. the sensor is ac complished with LM335 temperature transducer 7C 0 This transducer at taches with a thermally conductive cement to the TO 5 header leads of IRSI According to Dexter Applica tion Brief 2 the leads of the detector is the best place to monitor the tem perature of the reference junction The value of R O is chosen to be as large as practical to minimize self heating of C5 The temperature compensating circuit is made up of IC2 R6 R6 R9 and ICS Say You Saw It In Modern Electronics GNDo M3IA NOL1OS8 Jrio2z LSHI H9 3Ssvo AS O 0994 21N1 991 8 LEBZINT ASt d ino L9 50164 NI MS 78 Yt L 6ZW1 HOD V Id 8 bY y C zani Tw 725 1931 SEEINT PUE SEENT f f 1x8 885 Thermometer Accessory November 1990 MODERN ELECTRONICS 25 Fig 1 Complete schematic diagram of Infrared nu m oo s i 4 as lo SM3IA WOLLOa T T T em DP Ge mmm GP EE nnum qanm cd J91auJ ol Ld i M81 LEH ZL bdO vol MOI 3LON Say You Saw It In Modern Electronics aT a i ee E o6 x m nyv an 2 11i M Semiconductors D1 1N914 or similar silicon diode IC1 thru IC4 OP 177 precision oper ational amplifier see text IC5 LM33
197. thermoplastics with ther mal tools requires some practice at first to master it For hot punching with little or no melting of the plastic the rate of heat flow and tip tempera ture is just sufficient to allow the tip to be forced through the plastic with moderate downward pressure on the tool The tip softens the plastic and you push the tip through the plastic At appreciably higher tempera ture the plastic melts rapidly and very little force if any is needed as the tip penetrates the plastic How ever high heat often produces acrid toxic fumes and fouling of the tip with sticky plastic Therefore the objective is to use the tools at lower temperature to avoid fumes and fouled tips Practice on scrap pieces of vinyl siding ABS plastic taken from TV cabinets and plastic housewares until you perfect your technique Initially Fig 3 Hole templates and switch bodies aid machining of panels operate the soldering iron at 117 Say You Saw It In Modern Electronics November 1990 MODERN ELECTRONICS 21 volts Then after a 3 to 8 minute warm up period position the iron vertically and push down on the plas tic while moving the top of the iron in a small circle Place a piece of tablet back or chipboard under the plastic At 117 volts the tip is likely to be too hot penetration will be rapid and some sticking of plastic to the tip will occur If so lift the iron after pene tration and quickly remove the waste slu
198. tic roller ball The barrel has two square buttons one above the other with a raised bump on the bottom button so that it can be lo cated by feel This bottom button by the way corresponds to the left button on a standard mouse while the top MousePen button acts as the right mouse button When holding the MousePen like a writ ing instrument your finger naturally falls on top of the bottom button you don t have to hunt around for it Weight of the MousePen is just an ounce or two A thin cable coming out of the top of the body is terminated in a small PS 2 type DIN connector for the standard model a DB 9 connector for the model meant to be used with laptops or a connector for Apple s DeskTop Buss on the Macintosh model Appoint sup plies an adapter with the standard model that lets you use the MousePen with DB 9 and DB 25 serial ports as well as the PS 2 s DIN port As with most pointing devices the MousePen comes with two pieces of soft ware a set of menu utilities and a paint program called TelePaint I didn t bother examining the menu utilities I ve looked at other similar utilities in the past and have been uniformly unimpressed with software that tries to add pull down menus to programs that really weren t de signed for them When using Wordstar or 1 2 3 I ve gotten so used to the way the command keys work that trying to use pull down menus just slows me down These menus work best when they hav
199. tly above the floor to permit air to circu late around it Checkout amp Use Set both switches on the Stereo Au dio Test Box to LOAD Connect a multimeter set to the ohms function across Left Channel AMPLIFIER IN PUT binding posts BP3 and BP4 for the Left Channel and note the read ing obtained It should be approxi mately 8 ohms Repeat for the same numbered AMPLIFIER INPUT binding Say You Saw It In Modern Electronics pests in the Right Channel Then make sure that there is complete iso lation infinity reading between the Left and Right Channel Inputs With the switches still in the LOAD position you should obtain an ohm meter reading of infinity across SPEAKER OUTPUT binding posts BP and BP2 in both channels Set the switches to the UNLOAD position and use your ohmmeter to check for con tinuity between the AMPLIFIER IN PUTS and SPEAKER OUTPUTS You should obtain an infinity reading at all instrument binding posts BP5 through BP with the switches set to UNLOAD Connect the common lead of the multimeter still set to the ohms func tion to the metal enclosure Then touch the hot probe to each bind ing post in turn while observing the display In all cases you should ob tain an infinity reading overrange reading if you are using a digital mul timeter set to the highest range at all binding posts If you fail to obtain the proper reading at any point in the above pro cedure double che
200. to F should cause the red F LED to light For preliminary calibration use a thermometer to determine ambient room temperature Assuming the room is at 72 F point the probe at an inside wall for optimum accur acy tape the sensing area of a good quality contact thermometer to the wall Adjust R 6 so that 72 milli volts is displayed by the meter For many purposes this is the only cali bration required Now close your fist for a minute and then point the tip of the probe at your opened hand positioning it within an inch of but not touching your skin The meter should indicate atemperature between 89 and 96 F with 93 F being typical If the tem perature is outside this range addi tional calibration is warranted Continued on page 77 November 1990 MODERN ELECTRONICS 31 Say You Saw It In Modern Electronics wwWw americanracdiehistorv com Project A Precision Low Voltage DC Power Supply This laboratory grade power supply offers two user selectable output voltage ranges is short circuit protected and can go all the way down to 0 volt By Dennis Eichenberg ircuit designers service tech nicians and serious electron ics experimenters can bene fit from use of a laboratory grade low voltage power supply Labora tory grade usually means when one is considering a very expensive com mercial product Fortunately you can build a laboratory grade power supply such as the Lo
201. tom of the device Ed Cleaner Copy e The etching and drilling guide for the main pc board in Part 2 cf the Dual Application Telephone Security System that ap if TONS Arneg rhs WW peared in the July 1990 issue of Modern Electronics appears to have a few short circuits between closely spaced traces Any chance of getting a fclean copy J A Furstman Brooklyn NY The original pc guide appears to have suffered from ink bleed during printing Here it is cleaned up but shown at 7596 actual size You can easily clean up the original by working from this copy Alternatively you can have this blown up to actual size for direct use Also note that the trace that originates at the pin 12 pad for IC7 and passes between the pads for pins 11 and 12 for IC6 and terminates at the pin 21 pad of 1C2 should also be connected to the pin 12 pad for IC6 Ed Say You Saw It In Modern Electronics Our huge inventory of over 15 000 different items is constantly monitored and re stocked to virtually eliminate backorders and get your parts and com ponents to you FAST rami ione Fe cele CAGE PO craft NAAA wener M Tec m AA i A j A 1 UA GE pyle i A 11 88s pueller and e SE RV Sanap You lt find i ICE mon ted of Our friendly knowledgeable Sales Reps are Just a quick TOLL FREE call away to take your order or provide product if N technical assistance when you N A ne
202. ts of the circuitry are satisfied by the relatively simple C6 1C7 1C8 pow er supply arrangement Bear in mind that the values of sev switch Digi Key Cat No SW121 ND Main printed circuit board or perfor ated board with holes on 0 1 centers and suitable Wire Wrap or soldering hardware and enclosure see text detector pc board sockets for all DIP ICs 3 contact plug socket pair Digi Key Cat No A1493 A1436 optional see text 9 volt battery snap con nector and holder three conductor cable w th red green and black in sulated conductors 14 L x ID yellow CPVC pipe 14 L x 12 ID white PVC pipe S L x 1 ID white PVC pipe epoxy cement cable tie insulation duct tape aluminum paint solder etc Note The following items are available from Magicland 4380 S Gordon Fremont MI 49412 Complete kit of parts including all ICs main and probe pc boards and all oth er compoaents pipes cables etc but not including IRS1 battery and optional items Kit No IRTA MAGI 49 50 OP 177 op amps each 2 50 Digi Key is located at 701 Brooks Ave S P O Box 677 Thief River Falls MN 56701 0677 tel 1 800 344 4539 L M eral resistors used in this accessory depend on the geometry and material of the thermopile probe For in stance the value of R2 depends upon the interral diameter and length of the pipe in the probe assembly So keep in mind that the values given in Fig 1 and specifi
203. tured with nichrome fuses and low power Schottky technology and are ideally suited for spe cial environment applications required in space and aircraft systems The R29771 and R29773 are available over the commercial and military temper ature range in 24 pin 0 3 and 0 6 DIPs In 100 piece quantities pricing for these devices starts at 9 ME Say You Saw I In Modern Electronics WPC CAPERS Life amp Death and The MousePen By Ted Needleman With the holidays on the way I thought it might be fun this month to look at a few things that you can hope for or buy for yourself Life amp Death My mother always wanted a doctor in the family She somehow never got over the fact that her children chose less glamor cus careers Well mom I may not have gone to medical school but now with Life amp Death from The Software Tool works your first born is examining pa tients ordering tests and performing an Occasional operation Life amp Death is an interesting package It s not quite a game though it is both fascinating and absorbing It is within limits a stimulating and educational medical simulation You become a surgi cal resident at Toolworks General Hospi tal where you re responsible for examin ing diagnosing and treating a variety of abdominal ailments Booting up the program you find yourself greeted by the floor nurse and asked to sign in Once you have you re directed to various ill patients in s
204. two exciting proi ect books packed with complete plans for building a wide variety of useful electronic devices The First and Second Books of Modern Elec tronics Fun Projects both Howard W Sams publications are now available You ll find all the how it works informa tion schematics photos drawings printed circuit guides and the parts sources to make it a snap to build al most 50 useful unique electronic de vices at modest cost Discover how these circuits and mod ern electronic devices perform their ma gic Learn practical electronic technol ogy the painless way and enjoy doing it All projects are based on material pub lished in Modern Electronics with up dates and revisions They ve been built and tested by the original authors Chapters are divided into Intro To Elec tronic Projects Home Electronics Audio Video Electronics Security Elec tronics Computers Test Equipment and Electronic Designing There s something for everyone Look at what you can build and take pride in Digital voltmeter accessories high frequency ac probe true rms adapter temperature probe Car projects anti theft alarms en gine tachometer Life saving detectors gases amp mi crowave leaks HAM RADIO BOOKSTORE GREENVILLE NH 03048 Name a Fe Address i City u I B State Zip Check Card No Expires MasterCard VISA Signature a O a Signature required onall charge orders
205. uctive winding is sud denly cut off the circuit will ring causing relatively large voltage spikes to appear at the collectors of the tran sistors This condition can be further aggravated in poorly constructed transformers that do not have tight magnetic coupling between the two halves of the primary In the design example we will step through later a bifilar winding technique is used for the primary This type of winding produces a transformer primary with the tightest possible coupling and minimizes the amplitude of the ringing voltage Circuit Constants The value of RI in the circuit must be calculated for each converter design since its value is determined by the voltage of the power source and full load transistor collector current The purpose of R7 is to forward bias the transistors to ensure proper startup of the circuit when power is first applied Too large a value will result in a circuit that will not start under load while too small a value will result in excessive input current to the circuit and lower con version efficiency A simple way to arrive at a value for RI is to assume a required base current of about 10 percent of the in put current to the circuit and then us ing Ohm s law to calculate the re quired value Include in the calcula tion the 0 7 volt emitter to base drop especially in circuits driven by very low voltages For example if the in put current is 100 milliamp
206. ugs Then wire the switch closure transistors to separate lugs on the terminal strips Do not forget to also terminate the ground wire from the circuit board assembly at Vc of the tone circuit If any output shares the same destina tion jumper these connections on the circuit board assembly or assem blies Do not attempt to terminate more than one wire at any solder pad on the keypad If you are building more than one Speed Dialer solder the wires to the appropriate lugs of the terminal strip using a 1N914 di ode in each line to isolate the IC out puts and transistors from each other and each assembly from all others Wire the transistors in the proper sequence For example if you are Organize and Protect Your Copies of B ll MODERN ELECTRONICS Now there s an easy way to organize and keep copies of your favorite magazine readilv available for future reference Designed exclusively for ME by Jesse Jones Industries these custom made titled cases and binders provide the lux ury look that makes them attractive additions to your book shelf desk or any location in your home or office Whether you choose cases or binders you ll have a storage system that s durable and well organized to help protect your valuable copies from damage Vases and binders designed to hold a year s issues may vary with issue sizes e Constructed of heavy reinforced board covered with durable leather like material in co
207. uits in many applications you reap all the benefits these systems have to offer and will be employing the most mod ern approach to power supply design ee Se ee a Ii 54 MODERN ELECTRONICS November 1990 Say You Saw It In Modern Electronics WWW americanradiohistorv com Bill ELECTRONICS NOTEBOOK mm By Forrest M Mims III Thanks to digital calculators and com puters manipulating numbers has be come exceedingly easy to do Even though these operations are most often accomplished by means of digital cir cuits there is still a very important role for analog circuits that process numbers Consider division It s easy to divide one number by another with the help of a calculator or computer But how do you divide one voltage by another And why would you even want to perform this op eration in the first place The quotient of one quantity divided by another is the same as the ratio of the two quantities There are many applica tions in which it is very important to know the ratio of two values For exam ple in the chemical industry ratiometric calculators are used to control the ratio of chemicals being transported to a mixing chamber The same technique can be used to control the ratio of ingredients in the production of everything from dog food and cake mix to cement and paint Ratio calculation can also be used to determine differences in the signals from transduc ers that measure strain force accelera tion e
208. verify that it uses a TCM5087 or TP5087 chip If it does you are in business If not replace the instru ment with one that does use either of these particular chips Next find a way to access the row and column inputs to the chip In many desk type phones this can eas ily be accomplished via solder pads located just under the keypad see Fig 2 that connect the chip to the key switches Incidentally a desk style telephone instrument has enough room inside it to easily ac commodate the circuit board assem bly of the project and battery inside Q3 2N2222 R CE R5 100K 8 2N2222 R gt m a O R6 i gt is 100K c Q5 3 2N2222 Rig Uu db D R7 T 100K cl2 Q6 2N2222 Rv e a R8 z 100K cle O E 2N2222 R R9 ae 100K C Fig 1 Complete schematic diagram of the circuitry used in the Area Code Speed Dialer Say You Saw It In Modern Electronics Wm J JaAAZA smercanradinhictory com November 1990 MODERN ELECTRONICS 45 SS es E E ML E SER rae EN e a T 0 Em mei PARTS LIST Semiconductors IC1I TLCSSS timer IC2 4017 decade counter divider Q1 IRF 511 or any general purpose power type MOSFET Radio Shack Cat No 276 1718 or similar see text Q2 thru Q7 2N2222 or similar gener al purpose npn silicon transistor see text Capacitors C1 C3 1 pF 16 volt electrolytic C2 0 1 p 16 volt disc C4 10 pF Resistors 4 watt 10 tolerance R1 R3 10 000 ohms R2
209. w Voltage Pre cision DC Power Supply described here for only moderate cost This Power Supply provides a clean precise output that is adjust able from 0 to 9 volts dc which can be used in instrument calibration and circuit testing as well as for general bench tasks Two user selectable ranges are available a low range that gives very fine resolution control for 0 to 150 millivolt outputs and a high range that starts at O and goes up to 9 volts Both deliver up to 2 am peres of current and both feature current limiting for short circuit pro tection With the components speci fied maximum ripple is a low 2 milli volts peak to peak Separate voltmeter and ammeter movements are built into the Power Supply to provide simultaneous indi cation of output voltage and current The voltmeter automatically switches range when the output voltage range selector is operated About the Circuit Shown in Fig 1 is the complete sche matic diagram of the circuitry used in the Low Voltage Precision DC Pow er Supply Power from the 117 volt ac line enters through the ac line cord shown at the upper left The incom ing 117 volts ac is stepped down to 25 2 volts dc by power transformer T1 The center tap on the secondary side of T1 is grounded so that full wave bridge rectifier RECTI can provide both positive and negative 32 MODERN ELECTRONICS November 1990 WWW americanradiohistorv com voltages referred to ground for th
210. way A quick non analytical way of de termining maximum measurement range of an object is to first place the end of the probe as close as possible tothe object and notethe reading ob tained As you pull back the probe from the object the reading should remain fairly steady until maximum distance is obtained Beyond this dis tance the reading starts to change significantly Of course if the tem perature of the surroundings is the same as the object the reading re mains the same regardless of how far the object is from the probe For optimum sensitivity set a 31 2 digit DVM or DMM in its 200 milli volt full scale range to display de grees directly without the confusion of a decimal point Set to the 200 mil livolt full scale range the meter pro vides the measuring system with an accuracy of a tenth of a degree Nev ertheless accuracy is not increased and at this high sensitivity setting the 0 1 millivolt digit in the display will appear to fluctuate due to noise from various sources If you set your meter to the 2 volt full scale range only full degrees will be displayed and the decimal point may cause confusion but the display will be steady with no loss in accuracy A primary inherent source of error in infrared thermometers has to do with guessing the object s emissivity Emissivity has to do with the ratio of infrared radiation that an object emits to the infrared radiation a per fect black body radiat
211. wever power sup ply potential snould be at or very near a regulated 15 volts Moreover each side of the power supply should be bypassed by connecting 10 microfarad and 1 000 picofarad capacitors from the and supply points and circuit ground This may not be necessary if you use very short leads between the power supply and the circuit Figure 10 is the schematic of a circuit that provides a ratiometric measurement of the relative light falling on two photo detectors The DIV100 can also be used to compute the percentage difference be tween a reference voltage and an un known voltage It can be also used in vari ous kinds of automatic gain control and voltage controlled filter applications See the DIVIOO data sheet for additional information The DIV100 is made by Burr Brown Corp P O Box 11400 Tucson AZ 85734 Single quantity price is 36 60 60 MODERN ELECTRONICS November 1990 Say You Saw It In Modern Electronics WWW americanradiohistorv com Going Further While digital computational circuits pro vide much greater accuracy than analog circuits analog computational circuits sometimes provide a much simpler way to solve a problem when absolute accuracy is not required In any event even digital circuits are only as accurate as the A D converters that supply their inputs If you would like to learn more about analog computational circuits one of the classic references in the field is Nonlinear
212. will be easily accessible but wil not interfere with either the circuit board assem bly or the internal workings of the telephone instrument If you are building two or more Speed Dialers prepare an enclesure in which to house them by drilling mounting holes for the individual switches and an entry hole for the power cord from the external dc power supply Following Fig 1 carefully solder the free ends of the wires coming from the transistors connected to the outputs of C2 to the appropriate row and column pads on the keypad of the telephone instrument as shown in Fig 2 Again if you are building more than one Speed Dialer mount a multiple lug terminal strip inside the separate enclosure and run wires from the keypad solder pads to Continued on page 76 T my ere aan C Ci QG Qo gt ISESE LN A Ma G se xh AXM Ani Sud Fig 2 Connections between Speed Dialer circuit board DESDE y and ele BROHE instrument keypad are made with insulated stranded hookup wire November 1990 MODERN ELECTRONICS 47 Www americanradighistory com Technology Dc to Dc Converters A simplified approach to designing and building circuits to convert one dc voltage to another By Anthony J Caristi ecent advances in electro R magnetics have created revo lutionary new powering schemes that are now used in many electronic instruments and devices Ac powered electronic equipment have heretof
213. x Simplifies connection of test equipment to audio gear for troubleshooting and repair By Irving E Farnham aking connections for test ing audio equipment can be a real hassle Ordinari lv you end up with a tangle of cables that often have to be transposed dur ing tests Moreover noninductive loading resistors are often used that yield less than reliable measurement readings Our Stereo Audio Test Box provides an elegantly simple solution to all this The Box has separate left and right channel switches for loading and unloading resistors and individ ual stereo channel amplifier inputs and speaker outputs Multiple out puts accommodate a variety of test instruments including a multimeter and oscilloscope All input and out put connections are made through five way binding posts to accommo date any possible type of cable ter mination About the Circuit Shown in Fig 1 is the complete sche matic diagram of the circuitry for one channel of the Stereo Audio Test Box Two identical but independent such circuits are required for full stereo testing As you can see the circuitry is very simple It consists of a variety of binding posts for connection of the audio and test equipment a dpdt switch and a high power loading re sistor for each channel Setting 57 to its LOAD position places the 8 ohm 100 watt inductive load of resistor RI across the output circuit of the NN uu Pate x Tai y e ie Au
214. y Capacitors C1 C4 2 000 4F 25 volt electrolytic C2 C5 90 1 4F ceramic disc C3 C6 0 01 4F ceramic disc C7 1 0000 amp 4F 25 volt electrolytic Resistors watt R1 R2 150 ohms 1 watt 10 tol erance R3 6 800 ohms 1 tolerance R4 1 500 ohms 1 tolerance R5 750 ohms 1 tolerance R6 470 000 ohms 10 tolerar ce R8 2 200 ohms 10 tolerance R10 R11 470 ohms 10 tolerance R12 0 3 ohm 3 watt 5 tolerance R13 0 5 ohm 3 watt 59 9 tolerance R14 4 700 ohms 5 tolerance R15 680 ohms 10 tolerance fier 1C4 which buffers the signal Potentiometer R9 permits nulling zeroing the output signal from C4 when potentiometer R7 is set to its minimum position The output at pin 6 of C4 goes to the base of series pass transistor Q via bias resistor R O Over current protection is provided by Q2 This transistor senses the output current of the power supply flowing through R12 Capacitor C7 provides circuit output filtering and resistor R8 pro tects C4 from shut down transients Output current of the power sup ply into an external load is indicated by ammeter M1 and output voltage is indicated by voltmeter M2 Both meter movements are identical 1 volt R7 10 000 ohm panel mount 10 turn potentiometer R9 50 000 ohm pc mount trimmer potentiometer Miscellaneous BP1 BP2 Five way binding post or banana jack one red one black K1 117 volt ac relay with 3 ampere dpst contacts M1
215. y Many finish in 12 months or less Students and graduates in all 50 States and throughout the World Established Over 40 Years Write for free Descriptive Lit erature porci Ra ML GIE 4251 CYPRESS DRIVE LE JACKSON MISSISSIPPI 30212 CIRCLE NO 81 ON FREE INFORMATION CARD LEARN TO NN CLEAN MAINTAIN REPAIR FAX MACHINES HUGE NEW adii Hall SN NS SR SS CHER cmm Voce 0m Over 8 mililon Fax machines in homes offices predictions are for over 25 million by 1992 B Work from your home van B Home study program gets you started servicing fax machines in 2 weeks P No special tools equipment needed B Earn additional profits selling fax supplies e Fax machines are not cheap therefore you can get good for the repair e Average Fax machine requires professional service every 18 months e Home study training program includes full instruc tions on EVERY ASPECT of Fax maintenance repair FULL COVERAGE of how to set up your home based service business FREE DETAILS CALL 1 800 537 0589 Or Write To Viejo Publications Inc 5329 Fountain Ave Dept ME FX Los Angeles CA 90029 CIRCLE NO 98 ON FREE INFORMATION CARD November 1990 MODERN ELECTRONICS 8l m l ahi ADVERTISERS INDEX RS 76 AMC Sales e eee 77 Ace Communications 75 78 All Electronics 79 B amp B Electronics 78 CQ Buyer s Guide 7 79 C amp S

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