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1. XBY 9C200H ASC A XBY C2 H ASC T XBY C2 H ASC C XBY C2 H ASC H FOR I l TO 3 XBY C2 H 2AH NEXT I END 42 MODERN ELECTRONICS May 1989 REM clear display REM select 8 bit data 2 logical lines REM turn display on cursor off REM increment address counter after each write REM select position 1 on display REM write to display REM write TEMP to display REM select position 9 on display REM write WATCH to display REM write to display Say You Saw It In Modern Electronics pin 1 on the double row header and from pin 20 to pin 10 of JC 2 If at any point the meter doesn t register the proper voltage power down the circuit and locate the source of and rectify the problem be fore continuing Wheneverytaing looks okay pow er down the circuit and plug C 72 and IC15 into their respective sockets making sure you properly orient each IC and that no pins overhang the sockets or fold under between the ICs and the sockets Then connect M s ribbon cable being sure to observe proper orientation for pin 1 If possi ble insert a new or freshly erased EPROM into 7C9 s socket This will allow you to take advantage of the 8052 s special PROG2 command which will be described later Boot the Microsys to MCS BASIC 52 as before configure your terminal for communication with eight bits one stop bit and no parity Connect the Microsys to the serial port of y
2. ec NEW IC TESTER 149 00 SIMILAR TO BELOW EPROM PROGRAMMER PLUGS N TO YOUR PC OR XT TESTS ALMOST ALL 14 16 AND 20 PIN 74XX SERIES INCLUDES STANDARD POWER S AND LS DEVICES ALSO TESTS CD4000 SERIES CMOS SOFTWARE INCLUDED CAN EVEN DETERMINE PART NUMBERS OF MOST UNMARKED AND HOUSE NUMBERED DEVICES WITH SIMPLE MOD THIS UNIT CAN ALSO TEST 6 4K AND 256K DRAMS WITH MANUAL AND SOFTWARE 149 PERFECT FOR SCHOOLS 10 AMP SOLID STATE RELAYS ELECTROLS S2181 v CASSETTE MECHANISM Alpine cassette om Aner u CN Includes gt BigP lape head Mitsutsh 8 MET 3RF 28 13 2 Vdc motor belt pulleys capstan last forward rewind and eject actuator Does not include amplifier Section 612 X5147 X 1 Ys CATs CMEC S5 7 50 each 10 tor 65 00 LED S amp T1ANOARD JUMAO D USED T 1 9e vg MED Cate LED 16 ter 81 0 100 ter 13 0C GREEN Cats LEDR 10 tw 82 00 100 kw 41700 v LLOW Cate LEDS STROBE KIT CONTROL Rated 5 to 10 V c will operate on 3 32 Vdc LOAD 10 amp 240 Vac 2 U X1 34 X 7a CATS SSRLY 10B 950 each OUANTITY DISCOUNT 10 for 85 00 25 tor 175 00 50 ior 300 00 100 tor 500 00 Vanabie rate strobe kit flashes be tween 60 to 120 times per minute Will operate on ether 6 or 12 Vdc depend ing upon how you wire the circuit Comes complete with P C board and instructions for easy assembly CAT amp STROBE 1 750 each 6995 ASSEMBLED amp TESTED TRANS
3. 99 Available sep arately are double sided pc board with plated through holes Part No PCB 2210 25 9 volt dc 300 mA plug in power supply Part No AC 22 9 99 Ni Cd battery Part No NiCad 22 20 enclosure and hardware Part No CAB 22 20 00 Also offered is an as sembled and calibrated unit Model 2210 for 189 Add 5 for postage and handling Florida residents please add 6 state sales tax counters that feature more and short er gate time selections than the com pact portable counter Optoelec tronics Model 2210 whose con struction plans were described in de tail last month You can compare its fastest 0 1 second time with Opto electronics Model 8024 S s 0 01 sec ond gate period But then you re talking about a larger heavier instru ment that costs almost four times as much as the project Ten years ago a counter meeting the basic specifications of the com pact counter would have cost thou sands of dollars and likely would be mounted in a 19 inch rack Use of such counters was generally limited to engineers or technicians Today however digital frequency counters are even utilized by non technical operators from law enforcement officers to scanner buffs The operating hints described here will serve them as well as you technically oriented people in getting the most out of any modern counter The First Annual Amateur Radio Equipment Buyers Guide The Active Ham s Co
4. FOR FREE CATALOG CALL OR WRITE JAN CRYSTALS PO BOX 06017 FORT MYERS FL 33906 813 936 2397 RN eS MESE qm A TOLL FREE 1 800 237 3063 aii daa IN FLORIDA 1 800 226 XTAL FAX ORDERS 1 813 936 3750 CIRCLE NO 149 ON FREE INFORMATION CARD AMAZING SCIENTIFIC amp ELECTRONIC PRODUCTS PLANS uic voursert All Parts Available in Stock LC7 BURNING CUTTING CO LASER o RUB4 PORTABLE LASER RAY PISTOL TCC1 3 SEPARATE TESLA COIL PLANS TO 1 5 MEV 10G1 ION RAY GUN GRA1 GRAVITY GENERATOR EMLI ELECTRO MAGNET COIL GUN LAUNCHER KITS MFT3K FM VOICE TRANSMITTER 3 MI RANGE VWPM K TELEPHONE TRANSMITTER 3 MI RANGE BTC3K 250 00 VOLT 10 14 SPARK TESLA COIL LHC2K SIMULATEO MULTICOLOR LASER eBLS1K 100 000 WATT BLASTER DEFENSE DEVICE ITM1K 100 000 VOLT 20 AFFECTIVE RANGE INTIMIDATOR PSP4K TIME VARIANT SHOCK WAVE PISTOL PTGIK SPECTACULAR PLASMA TORNADO GENERATOR MVPIK SEE IN DARK KIT ASSEMBLED PTW1K SPECIAL EFFECT VISUAL PLASMA GENERATOR FOR GLOBES NEON TUBING ETC BTC10 50 000 VOLT WORLO S SMALLEST TESLA COIL LGU40 1MW HeNe VISIBLE REO LASER GUN TAT30 AUTO TELEPHONE RECOROING DEVICE GPV10 SEE IN TOTAL OARKNESS IR VIEWER LISTt0 SNDOPER PHONE INFINITY TRANSMITTER IPG70 INVISIBLE PAIN FIELD GENERATOR MULTI MODE B 223325 sS 595 555 6S 3S 169 50 74 50 CATALOG CONTAINING DESCRIPTION
5. Shown in Fig 1 B are the circuit details of the seconds and minutes counters Figure 1 C contains the details of the circuit for the drivers and light emitting diode matrices that make up the seconds and min utes dial displays Finally Fig 1 D contains the circuit details for the hours counter and LED display dial C2 100pF Note The following items are available from Jim Marshino Box 262 Goodland IN 47948 Kit containing all electronic components and both pc boards but no IC sockets or enclosure 89 50 plus 10 P amp H Also available double sided main and pendulum boards with plated through holes 34 50 all ICs 12 50 9 volt pow er transformer 9 packet of 143 LEDs all needed plus a spare 19 50 clock face kit 9 50 plain cabinet 45 or schoolhouse Regulator cabinet 75 Cab inets are available in either walnut or cherry lumber specify choice A wired clock not including enclosure is also available for 124 50 Add 2 50 P amp H for all orders except 10 for electronics kit either cabinet and wired clock Indiana residents please add state sales tax Following the pendulum circuitry are the basic clock circuits These are made up of two divide by 60 and one divide by 12 counters Each divide by 60 counter contains a 6 by 10 ma trix of LEDs as shown in Fig 1 C The LEDs are physically arranged to form two separate circles on the proj ect s dial face with the outer and in ner cir
6. ducted As you did last month solder the pins of the sockets to the copper rings through which they pass on the board Then wire the power supply and ground pins to the 5 volt and ground buses on the circuit board Using Fig 5 as a guide wire the cir cuitry associated with C 2 adding IC14 R17 R18 R19 C19 C20 and C21 to the board as required Mount IC14 R18 R19 and C21 as close to IC12as possible to minimize noise in IC12 s analog circuitry Wire the analog grounds ground connections to C21 IC13 and IC 4 directly to pin 8 of C 2 Connect and solder one wire from pin 8 of JC 2 to a ground point near C To permit flexible use of the proj ect itis a good idea to mount temper ature sensor C 3 at the end of a 5 foot long cable Use three conductor shielded cable for this to assure good immunity to noise Prepare the sensor cable as fol lows First remove 2 inches of the outer plastic jacket from each end If the shield is made up of wire mesh separate the wires at both ends back to the cut off plastic jacket and clip its conductors off ar only one end Twist together the fine wires of the braid at the other end and sparingly tin with solder If the shield is foil with a wire tracer unwind it back to the cut off plastic jacket trim the foil at both ends and clip the wire tracer at only one end Strip inch of insulation from all conductors at both ends of the cable tightly twist Say You Saw It In Moder
7. the 12V OUTPUT lead of the project The project s COMMON lead then goes to the 12 volt source The NORMALLY CLOSED lead of the Relay connects to the 12 volt input of the other audio unit and the NORMALLY OPEN lead connects to one side of the coil of an additional relay the other side of the relay s coil goes to circuit ground The additional relay s coil must be rated at 12 volts dc and its contacts must be conservatively rated to handle the current delivered to the speakers In addition to the project connec tions Fig 2 shows the schematic connections of the relay contacts to the speakers If you follow the cir cuits you will see that turning on one audio unit automatically disconnects the power from the other audio unit and transfers the speakers to the out puts of the active unit Pictorially illustrated and shown schematically in Fig 4 is a more so phisticated automatic switching ar rangement Here four speakers are switched between two audio units Two additional four pole double throw relays are required for this application The schematic diagrams in Fig 3 and Fig 4 are accompanied by a re lay contact legend The legend shows that normally open contacts are re presented by what looks like a capa citor symbol with neither plate curved while the normally closed symbol is the same with a slash through it As youcan see from the foregoing the Smart Car Relay is indeed a very versatile device
8. the undersigned do hereby declare under penalty of perjury that all products purchased now and in the future will only be used on 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 CRIMINAL AND CIVIL PENALTIES FOR UNAUTHORIZED USE Dated 1 Signed 818 716 5914 No Collect Calls 818 716 5140 Copyright 1987 PACIFIC CABLE CO INC Pacific Cable Company Inc 7325 RESEDA BLVD DEPT ME RESEDA CA 91335 May 1989 MODERN ELECTRONICS 9 NOW Training includes XT compatible computer plus NRI s remarkable Robotic Discovery Kits et training for industry s ottest new jobs as you uild and program complete robotic control systems Now you can get the skills in demand for the new jobs in industry today With NRI s new at home training in Robotics Technology you actually build a fully IBM XT compatible computer then use it to program and control working robotic systems each one engineered to recreate the exact operations performed by the robotic equipment found in today s industrial workplace It s no secret Industry is being transformed by technology with everything from precision electronic instruments to giant locomotives now being produced with the help of advanced robotic systems And with automation have come jobs thousands of
9. 225 2309 esf AA ZE 62 00 er 125 val 300 mi Cate MCO AA AA OZE 220 n wiTh SOLOER TASS CATs IF pit 01 OD amen 10 tor MO Cate M EW 4 te 100 1Ote 200 100 ke 1900 OPTO SENSOR SPDT PUSHBUTTON Cate emcee DERE 456 anh 12 wate 1200 man Cate MC D CALL OR WRITE FOR OUR ORDER TOLL FREE 800 826 5432 INFO 818 904 0524 FAX 818 781 2653 MINIMUM OF DER 1000 MAIL ORDERS TO ALL ELECTRONICS P O BOX 567 VAN NUYS CA 91408 TWx 8101010183 ALL ELECTRONIC OUTSIDE THE U S A SEND 2 00 POSTAGE FOR A CATALOG QUANTITIES LIMITED CALIF ADD SALES TAX USA 3 00 SHIPPING FOREIGR ORDERS INCLUDE SUFFICIENT SHIPPING NO C O D C O D We accepi Visa and MasterCard Texas Res add 6 1 4 Tax Forelgn orders except Canada add 209 P amp H Orders over 50 add 85 for Insurance a ee i E ES CIRCLE NO 108 ON FREE INFORMATION CARD ALL SALES SUBJECT TO THE TERMS OF OUR 90 DAY LIMITED WARRANTY FREE COPY UPON REQUEST TERMS Add 3 00 postage We pay balance Orders under 15 add 75 handling No CIRCLE NO 109 ON FREE INFORMATION CARD ADVERTISERS INDEX Page AMC Sales Ace Communications W All Electronics C amp S Sales m perator morena ic Cleveland Institute of Elec Command Productions 1 Consolidated Electronics Contact East Cook s Institute kal d Deco Industries Digi Key Corp Digital Research
10. 4 95 Build for less than 10 TV SCOPE Mmolrications To Tv Single or dual trac PENN RESEARCH Box 3543 Send for FREE CATALOG of Williamsport PA 17701 other plans and kits CABLE TV BOXES FREE CATALOG TRANS WORLD CABLE CO 12062 Southwest 117th Ct Suite 126 Miami Florida 33186 800 442 9333 REMOTE CONTROL KEYCHAIN E Complete w mini transmitter pee and 5 vdc RF receiver ca rica Set Fully assembled including plans to build your own auto alarm Write for more information Quantity pinnate available n eck Visa or M C ays refun ONLY 1 9 95 Add 3 shipping VISITECT INC 415 872 0128 PO BOX 5442 SO SAN FRAN CA 94080 SUBLIMINAL ANNOYANCE METER Mese ures sonic waves 0 40KHa A common Sues of Headaches 79 9 ATTENTION TECHNOCRATS INDUCTIVE AUDIO TRACER The SHMAGUE audio tracer lele you hesten to TAPE SAVER amem fielde Just bold the next to a Connects your scanner audio currents and recorder for ac component peeing PE ihe sound ae operated with internal spesker Only 59 SIGNAL INTENSIFIER RF PREAMPLIFIERS CB RFTR amplifies received signals i db AM 490 05 SSB vernon 64 95 SCANNER EFP 40 0 6 ama VAK TENNA 29 95 WHC UHF oe F con ava 30 00MHa For Scanner Ham 16db gain 69 os 4 TV FM Specify connector UHF a uh M operai VHF BNC F M la ne reception SUPER VAK TENNA 149 95 MANY MORE MODELS ELECTRON PROCESSING INC
11. 808 325 7707 BUY 20 000 oriental import products below wholesale Bevans Dept PE 9 King Richard Cha Baltimore MD 21237 o APEX Industrial Screwdriving Tools Free catalog Hex insert bits bit holders much EDUCATION i CONSOLIDATED C S BE 4 E G IT AYO M 3 GET THE ULTIMATE ELECTRONICS CATALOG Order your 260 page catalogue packed with over 10 000 money saving electronic parts and equipment Send 3 00 check or money order or Call 1 800 543 3568 today and Consoldated Electronics Incorporated 705 Watervliet Ave Dayton Ohio 45420 2599 NAME ADDRESS 2174 Union St Suite 22AB San Francisco CA 94123 more Shockey s 5841 Longford Road 0 l l 1 use your Mastercard or Visa l t l l Dayton OH 45424 513 236 2983 i ZiP TEXT TO SPEECH BOARD PC XT COMPATIBLE MAKE YOUR COMPUTER TALK A VERY POWERFUL AND AMAZING SPEECH CARD USES THE NEW GENERAL INSTRUMENTS SPO256 AL2 SPEECH CHIP AND THE CTS256A AL2 TEXT TO SPEECH CONVERTER THIS BOARD USES ONE SLOT ON THE MOTHERBOARD AND REQUIRES A COM SERIAL PORT BOARD MAY ALSO BE USEDINA STAND ALONE ENVIRONMENT WITH ALMOST ANY COMPUTER THAT HAS A RS232 SERIAL PORT FEATURES ON BOARD AUDIO AMP OR MAY BE USED WITH EXTERNAL AMPS DEMONSTRATION SOFTWARE AND A LIBRARY BUILDING PROGRAM ARE INCLUDED ON A 5 INCH PC XT DISKETTE FULL DOCUMENTA TION AND SCHEMATICS ARE ALSO INCLUDED NEW co
12. C 2 and stores it in the variable ADC Line 40 converts the byte to a Fahrenheit temperature and line 50 displays the temperature on the terminal screen The number 2 47 in line 40 repre sents twice the reference voliage at pin 9 of C12 Although the voltage across the reference diode is stable it can vary among individual ICs from 1 223 to 1 247 volts For greatest ac curacy in the temperature measuring circuit measure the voltage from pin 9 to pin 8 of C14 on your system and enter twice this value in line 40 in place of 2 47 To exit Program 6 s infinite loop use CONTROL C Program 7 writes the message TEMPWATCH minus the quotation marks in the LCD module s display Type in and run this program as you did before After running Program 2 adjust R20 to give the desired contrast on the display Because M1 is quite powerful in it self programming it is relatively straightforward Lines 10 through 40 in Program 7 initialize and configure the module by writing values to hex address C000 Address C000 enables MI by bringing line v6 low The ini tialization and configuration codes are described in the applications notes for M1 Line 50 selects position 1 on M1 at hex location 80 and lines 60 through 130 cause the message TEMP again without the quotation marks to appear in the first eight character positions of M1 The character codes for the letters in the message are the standard ASC
13. Co sponsored by Stereophile magazine and Nelson amp Associates the exhibition consists of five stations each of which represents milestones in consumer audio Many of the exhibit pieces still work and will be demonstrated Examples are the 1877 Edison Phonograph the 1896 Emile Berliner Trade Mark Gramophone disc player the 1925 hand cranked Victor Orthophonic Victrola the first stereo LP recording made in 1931 and featuring the Philadelphia Orchestra under Leopold Stokowsky the Model K 4 Magnetophon World War II German tape recorder the 1947 Webster Chicago 18 8 stainless steel wire recorder the 1953 Cook Binaural Record System and much more A Show ticket good for all three days is 15 mr Oa a EE EE IEEE INNEN EIE iei LLL LGB 8 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics WILETTERS 97 1 28 A Further Observations e Thank you for your review of Aldus PageMaker 3 0 in the January 1988 issue of Modern Electronics Though Mr Nee dleman is obviously familiar with the software there were a few inaccuracies in the report Firstly PageMaker s column guides can be created only with the Column Guides command from the Options menu though they can be changed or overridden without disrupting already placed text The horizontal and vertical ruler guides the review refers to as tools to define columns are meant to help main tain alignment and design consistency They do
14. Crimp and solder the free end of the 4 inch wire to one Jug on 3 Then crimp and solder the other two wires to the remaining switch lugs Connect the wire common to both switches to ground on the circuit board Connect S2 s other wireto pin 1 of JC2 and S3 s other wire to pin 2 of IC2 Route the sensor cable through a rubber grommet lined hole in the en closure s rear panel Switches S2 and S3 and module MI mount on the front panel the switches in suitable size holes and the module in a 2 by 1 4 inch slot you must cut into the panel In addition to the slot M1 requires that you drill four mounting holes for it in the front panel Cut the larger display window opening first making it large enough that the module fits easily in to it to obviate mechanical stress on the display When the opening is ready insert MI in the front panel and mark the locations for the four mounting holes Remove and set aside the mod ule and drill appropriate size holes in the marked locations Temporarily remove S1 from the front panel and label S s positions ON and OFF S2 RESET and S3 SET CLOCK on the front panel Use a dry transfer lettering kit and protect the legends with two light coats of clear spray acrylic Allow the first coat to dry before spraying on the next Mount MI using spacers of suffi cient length to assure that fit between M1 and the front panel is correct In stall the circuit board in its enclosure and co
15. No Need to Quit Your Job or Go To School This proven course is easy fast and low cost GUARANTEED PASS You get your FCC License or money refunded Send for FREE facts now o nmm wea eee COMMAND PRODUCTIONS FCC LICENSE TRAINING Dept 220 i P O Box 2824 San Francisco CA 94126 i Please rush FREE details immediately 8 NAME I ADDRESS city STATE ZIP MAIL COUPON TODAY j Lucsnaneenaace EE ES BW ELECTRONICS NOTEBOOK m Experimenting With Thermistors By Forrest M Mims III Thermistors are temperature sensitive re sistors that are extensively used in elec tronics Detection of temperatures of li quids gases both indoor and outdoor air included machinery electronic compo nents soil plants and animal tissue are among the many applications in which they can be found playing central roles Thermistors can also be used as surge protectors and timing devices In this column I ll discuss the various kinds of thermistors and how they work Pll follow this with several examples of applications for these simple but very ver satile components Thermistor Operation A thermistor is a resistor When its tem perature is increased the opposition to the flow of current resistance through it decreases Therefore a thermistor is said to have a negative temperature coeffi cient NTC The resistance of copper in creases and as a result copper has a posi tive temperature coefficient PTC
16. REM Program 9 display temperature on LCD module PRINT CONTROL C to quit XBY C H 1 XBY 0C000H 38H XBY 0C000H 0CH xBY 0C000H 6 DO XBY 0E000H 255 TEMP XBY 0E000H 2 47 100 255 REM clear display REM select 8 bit data 2 logical lines REM turn display on cursor off REM increment address counter after each write REM write to adc to start conversion REM get amp calculate temperature IF TEMP INT TEMP 5 THEN TEMP INT TEMP 1 ELSE TEMP INT TEMP DIGIT1 INT TEMP 100 DIGIT2 INT TEMP 190 DIGIT1 120 DIGIT3 TEMP DIGIT1 100 DIGIT2 1 REM select position l on display REM write ASCII codes of digits to display XBY 0C 000H 890H XBY 0C200H DIGIT1 448 XBY 0C200H DIGIT2 48 XBY C2 H DIGIT3 48 XBY 0C200H 0DFH XBY 0C200H ASC F WHILE l 1 END bit 1 is low which means S3 has been pressed Listing 9 combines features of Pro grams 6 and 7 It reads the tempera ture at C 2 s output then displays it on M1 Lines 20 through 50 initialize M1 Lines 70 through 80 get and cal culate the temperature at C72 Lines 100 through 120 divide the tempera ture reading into three digits and lines 130 through 180 write the three digits to the display To give the cor rect character codes 48 is added to each digit s value Finally the listing in Program 10 gives the full featured Tempwatch With this program the Tempwatch monitors temperature and displays the present maximum an
17. The NTC of a thermistor might at first appear to be an unusual characteristic However if you are familiar with photo resistors the NTC of a thermistor should seem perfectly ordinary Just as the resis tance of a thermistor falls as temperature rises the resistance of a photoresistor falls as light intensity rises Shown in Fig are the resistance char acteristics of a typical thermistor as a function of temperature At room tem perature this thermistor has a resistance of approximately 500 ohms Other ther mistors have room temperature resis tances ranging from a few hundred ohms to several megohms The curve in Fig 1 shows that a ther mistor is very sensitive to small tempera ture changes Indeed a thermistor can exhibit a resistance change of up to eight decades 10 000 000 to 1 over the tem perature range it is designed to monitor Another important feature of the curve shown in Fig 1 is its nonlinearity If a thermistor is intended to monitor rel i 1 o ww RESISTANCE 0 1 O SO 83 100 128 150 DS 100 TeEmpeRATURS F Fig 1 Plot of the resistance of a typical thermistor as a function of temperature atively small temperature changes its nonlinearity is usually not important That s because the resistance of a ther mistor is often linear with respect to tem perature over small temperature ranges However in applications where wide temperature ranges are encountered
18. lar and is supported by all VGA cards except the ones from IBM and Com paq The emulators are generally loaded into RAM from a utility menu but a few boards have an auto switching feature that senses the vid eo mode the software is seeking and automatically loads the correct emu lator for you Virtually every VGA card again except for those from IBM and Com paq also supports up to 256 colors tunately it s difficult to tell the two apart they both look alike While all the boards listed in the Where to Buy section of this article are register level compatible they may have siblings that are not Two such cases are the Quadram QuadVGA and Video Seven VEGA VGA both of which are currently available at very low prices through mail order houses with the claim that both are VGA regis ter level compatible In point of fact tiese boards are only partially register level compatible and mostly BIOS com patible On the other hand their more expensive counterparts the Quadram QuadVGA Spectra and Video Seven FastWrite VGA are fully register level compatible When shopping for a VGA board don t be fooled by claims of VGA com patibility If you re not sure of what type of board you re buying ask some one who does Just keep in mind here that while dealers are usually the most convenient source of information they don t always have the correct answer to technical questions A call to the techni cal depar
19. monostable multivibrator made up of IC2C and IC2D for a period of 0 43 second and the R6 C5 network IN IC1 OUT 7808 9Vdc COM input C1 O 1uF DISP1 LCDO004 C6 Say You Saw I In Modern Electronics 0 22uF 400V resets counter C3 to zero Under these conditions the motor will not run because the LEDs inside the four optocouplers are not turned on The four NAND gates that make up C5 are configured here as inverters They function as buffers that supply the 13 milliamperes of current re quired by the LEDs inside each opto coupler To start running the motor nor mally open pushbutton switch S must be pressed Counter C3 then changes its zero state to decimal 1 0001 This generates a pulse at the pin 6 Q1 output of JC3 which is cou pled through CSA and pulses on the internal diode of optocoupler C8 This enables R to transmit the voltage across C6 to the gate of QJ With diac D between C6 and the gate of Q1 however the triac does not immediately turn on As the 117 volt ac source passes through zero on each cycle alterna tion the charge on C increases Only when the potential across capa citor C6 reaches 30 volts which is the break over potential of the diac is DI triggered into conduction When the diac triggers on the charge on C s dumped into the gate and trig Fig 1 Complete schemaiic diagram of the ac motor speed controller IC10 MOC3010 Ic11 7 MOC30
20. on whether you re switched to upper or lower sideband from your fre quency counter s reading Specialized probes can enhance the utility of a frequency counter This can be the case with the counter proj ect at hand which could try to count a low frequency source such as an audio signal while having an inherent gigahertz GHz bandwidth The counter has to be able to distinguish between a low frequency signal and high frequency noise and harmonics that could be present To do this with our low cost com pact counter requiresthe use of an at tenuation probe such asa 10 x oscil loscope probe For instance you might have a 5 volt signal with a sig nal to noise ratio of 40 dB that could have a 50 millivolt noise level The signalis clearly sufficiently high to be counted The hat trick is simply to re duce the 5 volt level to the point where it s still high enough to be mea sured while at the same time the noise component has been reduced to Say You Saw It In Modern Electronics 10K 100K Fig 2 Frequency response plot of a low pass filter and schematic diagram of a 1 megokm Counter Input COAX COUNTER low pass probe the point where it cannot be counted In using this technique be sure that the counter is in the higher input impedance range A is 1 megohm in the project counter If you switch to the low 50 ohm impedance range B in the project counter the scope pro
21. put on screen two complete 8 5 by 11 inch or international A4 pages The other from Super Mac Technol ogy is the Spectrum 8 Series I Graphics Card that supports color gray scale and multimedia output when the transmitter is keyed Inser tion loss and VSWR are claimed to be negligible and current drawn by the unit is only 80 milliamperes at 10 to a 15 volts The circuitry is housed in side a weather resistant 2 x 2 x 1 5 plated metal box making it suitable for use in harsh environ ments 99 95 CIRCLE 34 ON FREE INFORMATION CARD Portable Static Meter The Static Surveyor CP911 from Charleswater Products Inc W Newton MA is a fully automatic hand held static meter that features an analog display movement and an audio alarm with a red light emitting and displays 1 024 by 768 pixels with 256 colors from a palette of 16 8 mil lion colors Other support cards for the 030 Di rect Slot include Kinetics Ethernet SE 30 for connection to Ethernet networks Dove Computer s Mara thon 120 96 SE 30 NuBus Adapter and FastNet SE 30 Ethernet adapt er MacPEAK Systems Orion SE 30 Cache Card that enhances the Mac SE 30 s performance with a 64K byte high speed static RAM cache Creative Solutions Inc has a line of Hurdler serial and parallel I O cards a prototyping card and a bus extender Finally Micron Technol ogy s Micron Parity Watchdog pari ty error detection device gives real time a
22. resistance of R3 is then R1 x R4 R2 Figure 11 shows how a thermistor be comes the unknown resistance Initially R4 is adjusted to balance the bridge Then tiny changes in the thermistor s re sistance hence its temperature will be indicated by the voltmeter which should have a high impedance input to minimize loading the circuit The values of the resistors aren t criti cal as long as they are known For exam ple if the thermistor has a resistance of 5 000 ohms at room temperature you might select 5 000 ohm resistors for R7 and R2 To permit a wide adjustment range R4 should have an adjustment range greater than 5 000 ohms say 10 000 ohms Figure 12 illustrates how to use a Wheatstone bridge as a differential tem eet Poe OO peni AG 6 x HOOT ie 9 yah n go s9 y q ger ous d 1e c9 i ae 9 iS af 2 We V es Pace yet ont o he S NOV yare Nery BCE net Sa sets nic e pine N EARN YOUR B S E E TS DEGREE THROUGH HOME STUDY Our New and Highly Effective Advanced Place ment Program for experianced 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 ali of the loose ends of your electronics background together and earn your B S E E Degree Up grade yo
23. 44 384 5 5 5 184 5 6 1 5 4 5 6 1 24 32 24 32 0 2 1 7 0 5 05 05 05 E 0 2 1 7 10 50 ooj Joojoo oo 30 10 E 150 Pressing TAB key presents the small two octave keyboard and lets you directly play sharps and flats CMS 1 MIDI Studio and Cakewalk soft ware I reviewed here last month but I must admit to preferring to input music from a synthesizer keyboard Another preferable method is to mouse a note around a musical staff Sev eral programs I ve played with briefly use this method and it s fun and quick to en ter music this way Even though I lacked the patience to enter much music with a text editor I don t think many of you will find the pro cess all that difficult though you may also find it tedious The sound from the C MS while not anywhere as good as the Oberheim Matrix 1000 is still pretty good especially when piped through a fairly good amp At 199 for the whole shebang it s a lot of fun Andif like me you have small children they will really get a kick out of animated musical numbers If you order a C MS be sure to order additional demo song disks Creative Music Labs gives you two and offers six others They re only 4 each and it s a lot easier to modify one of their songs than to enter your own from scratch and you ll be learning C MS notation along the way Documentation warns about the possi bility of some timing loop problems with demo
24. Berwyn IL 60402 CLASSIFIED ADVERTISING ORDER FORM Mail this form with payment to MODERN ELECTRONICS Classified Dept Hicksville NY 11801 Name Street Address City u DENN 76 N Broadway State Zip PRINT EACH WORD SEPARATELY Notethat P O Box numbers and telephone numbers must be counted as two words each Circle additional words you wish boldfaced at 20 more each initial boldface word is free Minimum charge is for 15 words 3 4 7 8 1l 12 15 15 16 16 PLEASE ADD Free Boldface 2 5 6 9 10 13 Loci ne Extra Bold Words 20 cents TOTAL PAYMENT ENCLOSED Check or Money Order Special Heading 6 Payment may also be made by MasterCard or Visa For this please fill in information below Credit Card Number 7 Print Full Name Expire Date E Signature m If a box number is used please supply your permanent address and telephone number for our records 88 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics CABLE TY EQUIPMENT CABLE DESCRAMBLER LIQUIDATION Major makes and models available Industry pricing Example Hamlin Combo s 44 each minimum 10 orders DEALERS ONLY Call West Coast Electronics 818 709 1758 CABLE EQUIPMENT CABLE TV Secrets the outlaw publication the Cable Companies tried to Ban HBO Movie Channel Showtime Descramblers Converters etc Suppliers List Included 8 95 Cable Facts Box 711 ME Pataskal
25. Computers 8 Electronics Book Club Electron Processing Inc Grantham Heath Co Information Unlimited Jan Crystals Kenwood USA Listen Electronics MCM Electronics Li Magnaphase Ind Inc ss Midwest Electronics NRI Schools OptoElectronics 4 4 Pacific Cable Co Inc Parts Express International Penn Research Trans World Cable Co KH U S Electronics Viejo Publications Visitect Inc Winston Arrington VGA from page 21 technique used by VGA to improve the MCGA screen image In MCGA information is duplicated every other line to create an illusion of more de tail while interlace scanning supplies new lines of data that actually add to the resolution of the image Interlace scanning is also required for the 1 024 by 768 extended VGA mode and requires an IBM Model 8514 or similar monitor In Closing There can be little doubt that VGA will be around for a long time to come as the text and graphics dis play medium of choice in personal computing It s already here and is solidly entrenched Furthermore VGA has the support of the software community Also in its favor is that it has its foot in the door of the future with its extended modes and pending VESA standard ME Smart Car Relay rom page 53 metal screw for which you drill a hole Whichever way you go use
26. MODERN ELECTRONICS May 1989 Carefully inspect your work for properly installed components and proper soldering If you are using a home made board make sure that all connections are soldered to the pads on both sides of the board If you lo cate any connections that have not been soldered or ones that have ques tionable soldering solder the ones missed and reflow the solder where necessary Check also for solder bridges particularly between the closely spaced IC pads If you locate any bridges remove them with desol dering braid or a vacuum type desol dering tool Set aside the pendulum board and place the main board on your work surface in the orientation shown in Fig 5 Begin populating this board by installing and soldering into place the sockets or Soldercons in the in dicated locations Note that no sock et should be installed in the location in the center of the board Again do not install the ICs in the sockets yet Then install and solder into place the resistors and diodes making sure that the latter are properly oriented before soldering their leads to the copper pads Next install and solder into place the capacitors Small capacitors C2 and C3 mount on the top of the board with the other components Large electrolytic capacitor C7 on the other hand mounts on the bottom of the board observe proper polarity when installing C7 Finish up installing components on the main board with the 132 light emi
27. N 2 DTEMP MAX DHR XHR DMIN XMIN GOSUB 230 280 N 3 DTEMP MIN DHR NHR DMIN NMIN GOSUB 230 210 WHILE 1 1 220 END 238 REM yrite to display subroutine teeeeeeesecenene 240 XBY 0C000H 80H REM select position 1 on display 258 FOR I 1 TO 4 XBY C20 H ASC S N I NEXT REM display message 260 REM display temperature 3 digits 270 DI INT DTEMP 189 D2 INT DTEMP 18 D1 10 D3 DTEMP D1 1090 D2 10 280 IF Dl 0 THEN XBY 0C200H 32 ELSE XBY 0C200H D1 448 290 IF D1 AND D2 0 THEN XBY 0C200H 32 ELSE XBY 0C200H D2448 309 XBY 0C2080H D3 48 310 XBY 0C200H 0DFH 3208 XBY 0CO00H 0COH 330 XBY 0C200H ASC F 340 REM display time REM display degree symbol REM select position 9 on display XBY C2 H 32 350 IF DHR gt 9 THEN XBY C200H INT DHR 10 48 ELSE XBY 0C200H 32 368 XBY 0C200H DHR 198 INT DHR 198 448 378 XBY 0OC200H INT DMIN 18 48 380 XBY 0C200H DMIN 10 INT DMIN 180 48 390 FOR I 1 TO 50 44 MODERN ELECTRONICS May 1989 XBY 0C200H ASC XBY 0C200H 32 Say You Saw It In Modern Electronics mand to review it and verify that all lines are entered correctly CON TROL S and CONTROL Q will stop and start the listing of a long pro gram on the screen MCS BASIC 52 is usually quite helpful in generating error messages so these may also help you in tracking down the source of problems To save the program in EPROM snap B and B2 into
28. Of course the listener is still prohibited from using the information heard for personal gain or disclosing its con tents to other parties not invoived un less by the express permission of the originating party Ed This enables one to catch the frequency that say a patrol car officer is transmitting on and listen in through your scan ner The same holds true for fire de partent transmissions commercial two way mobile radio communica tions and other transmissions When frequency catching from a car an external antenna is recom mended such as Antenna Special ties Model MON 52 When properly configured a drive through a mili tary base or airline terminal area can be interesting projects Since the frequency counter proj ect combines high sensitivity with portability it lends itself to the cloak and dagger world too Simply walking around a room with the hand held counter s telescoping an tenna fully extended will likely lock in on a bug if it s there Profes sional r f listening devices are almost exclusively in the 100 MHz through 450 MHz range and typically have at least 100 milliwatts of power Once you know a bug is present you ll likely find it with some careful searching Amateur spies with no ac cess or money to commercial listen ing devices will use cheap FM wire less microphones which have very low power outputs The counter project won t pick up its frequency as readily as the profes
29. R 5000 is a high performance top of the line receiver with 100 memory channels and direct keyboard or main dial tuning makes station selection RZ Wide band scanning receiver verter Options must be used ub ae ruta The RZ 1wide band scanning receiver covers 500 kHz 905 MHz in AM and narrow or wideband FM The automatic mode selection function makes listening pecifications features and prices are subject t 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 hange without notice or Obligation HF VHF NBI DOWN RE Lara uP Q jc4 AGC RF AUT NB2 NOIC4 PES a gt 19 R 2000 The R 20C0 s an all band all mode receiver w th 10 memcry ch nnels and ppany deluxe featues suchas program mable scannin
30. RCA Hitachi Fisher Sanyo Lloyds Panasonic Sony Sharp JVC Samsung TMK GE Mag navox and more Idler assemblies pinch roller sensing transistors switches and lamps are included in this comprehensive kit You also save over 20 00 Kil Contains replacements for Sharp 2 NIDLOOO5 2 NIDLOOO06 1 NPLY VOO51 Panasonic 2 VXPO0329 2 VXPO0401 2 VXP0344 2 VXP0521 ACA 1 150614 1 164113 1 150650 Hitachi 1 641311 Fisher Sanyo 1 143 0 4204 00300 2 143 0 4804 00100 1 143 0 4904 00900 1 143 0 7411 20002 RCA Hitachi 2 up down Switch 5 161757 sensing transistors Panasonic lamps 2 XAMQ27P 150W 5 XAMVOO 9 5 XAMV125 1 Molybdenum grease Norma dealer cosi of over 110 00 All parts are avail able individually for reorders 95 Plus shipping Order 400 950 ER ons roa 7 A VCR IDLER TIRE KIT This popular kit contains 150 of the most popular idler tires 10 each of 15 different Sizes With this kit in your stock room you can do over 90 of VCR repair jobs the same day saving time and money Also included is our comprehensive cross reference listing over 80 manufacturers assembly numbers and over 200 model numbers A 400 00 retail value All tires are available individually for reorders Order 5500 400 900 Plus shipping FREE CATALOG 736 REM reset max min subroutine s dk 746 MAX TEMP XHR HOUR XMIN MINUTE 756 MIN TEMP NHR HOUR NM
31. Sweep M0 1251 6 CRT Built in component tester TV Sync X Y Operation Top quality scopes at a very reasonable price Contains all desired features Two 1x 10x probes diagrams 8na manual Two year guarantee Autoranging DMM Digital Capacitance Meter Digitai LCA Meter M 5000 CM 1550 LC 1801 45 58 95 5 125 SCOPE PROBES P 3 65MH2 1x 10x 19 95 P 2 tOOMHZ 1x 10x 23 95 Fits all scopes with BNC connector Multimeter with Capacitance and Translator Tester True AMS 4 EM Digit Multimater 135 M 7000 9 Functions Memory and Data hoid Vr basic acc 3 digit LCD AC Clamp n Current Adapter ST 265 22 0 1000A AC M 3500 most DMM 1 acty Wide Band Signal Generators G 9000 129 RF Freq 100K 450MHz AM Modulation of 1KHz Variable AF output G 9500 with Digital Display and 150MHz bullt in Freq Ctr 249 Digital Triple Power Supply XP 765 249 0 20V at 1A 0 20V at 1A 5V at 5A Fully Reguisted Snort circuit protected with 2 Limit Cont 3 Separate supplies XP 660 with Anaiog Meters 175 F 1000 1 2GH 259 F 100 120MH Frequency Period Totalize 179 Self Check with High Stabilized Crystal Oven Oscillator 8 digit LED display E 05 DC Accuracy t Resistance j with Freq Counter vs and deluxe case Bench DMMS 55 CM 1500 Reads Volts Ohms Z Current Capacitors ES Transistors and Olodes with case SOLDERING STATION EMPERATURE CO
32. Turn on power to the project and adjust R4 for a reading between 5 4 and 5 6 volts Note that as you orient WORLD S SMALLEST WEATHER STATION THE AMAZING WEATHER COMPUTER THAT YOU CAN HOLD IN THE PALM OF YOUR HAND DIGITAR s new TWR 3 Micro Weather Station includes a computer precision wind vane and speed sensor with mounting hardware and 40 feet of cable For only 159 95 With the optional automatic emptying RG 2 Rain Collector 49 95 you can even monitor rainfall WIND SPEED RAINFALL Optional TIME OF DAY AUTO SCAN METRIC STANDARD WIND DIRECTION WIND CHILL s WIND GUST RECORD TEMPERATURE NICAD READY HVLOW TEMP RECORD s ONE YEAR WARRANTY MAGNAPHASE INDUSTRIES INC 1502 PIKE STREET N W MADE IN U S A AUBURN WA 98001 MIC amp VISA ORDERS ONLY 800 322 1502 INFORMATION 206 735 0374 FAX 206 735 9044 the project for best exposure to the sun the voltage will vary slightly Set R4 so that the maximum voltage ob tainable is between 5 4 and 5 6 volts as you orient the project for the best exposure This completes the calibra tion of the solar cell and amplifier R4 will need no further adjustment If you do not obtain the correct voltage reading at pin 14 of JCI check to make certain that the solar cell is wired intothe circuit in the cor rect polarity If it is measure the val ue of RI to be sure it is about 0 2 ohm and measure the voltage across it with the
33. We have touched here on only three possible applica tions for this device You will certain ly come up with more based on your needs ME Say You Saw It In Modern Electronics EXPAND YOUR CAREER HORIZONS ELECTRONICS EDUCATICN OF 10 VO 2121044 TODAY e a2 ae oiu p P ES Tne CIE Microprocessor Trainer helps you to learn ow circu ts with micropro gt essors function in computers START WITH CIE Microprocessor Technology Satellite Communications Robotics Wherever you want to Go in electronics start first with CIE Why CIE Because we re the leader in teaching electronics through independent study Consider this We teach over 25 000 students from all over the the handy reply coupon or card below to Cleveland Institute of Electronics 1776 East 17th Street Cleveland Ohio 44114 CIE udi Worid Headquarters Cleveland Institute of Electronics Inc 1776 East 17th Street Cleveland Ohio 44114 United States and in over 70 foreign countries And we ve been doing it for over 50 years helping thousands of men and women get started in electronics careers We offer flexible training to meet your needs You can start at the beginner level or if you already know something about electronics you may want to start at a higher level But wherever you stat you can go as far as you like You can even earn your Asscciate in Applied Science Degree in Electronics Let us get you started today Just ca
34. allow it to return to room tempera ture The maximum temperature display should now show the highest value measured and the time it Occurred Similarly you can test the mini mum temperature display by spray ing the sensor with an aerosol com ponent cooler The minimum tem perature display should show the coldest temperature measured along with the time it occurred To reset the maximum and mini mum temperatures to the current temperature momentarily press and release S2 If you have any problems in run ning this program usethe LIST com 18 REM 55 5 5 445 Dempwatch program 49Sh 44A RAARRARRARARRRA 20 STRING 25 5 30 XTAL 4915200 CLOCK 1 TIME 40 TEMP Q MIN 255 MAX HOUR 24 MINUTE 0 50 VREF 1 225 REM reference diode voltage 60 1 2 Now 2 Max 3 Min 70 XBY 0C000H 1 REM clear display 89 XBY 0C000H 73BH 90 XBY 0C000H 6 100 XBY 0CO00H 0CH 114 DO 120 ONTIME 60 770 138 XBY 0E000H 255 1409 TEMP XBY O0EO000H VREF 200 255 REM select 8 bit data 2 logical lines REM automatic increment of display address counter REM turn display on cursor off REM write to adc to start convert REM get temperature 158 IF TEMP INT TEMP lt 5 THEN TEMP INT TEMP ELSE TEMP INT TEMP 1 160 IF TEMP gt MAX THEN MAX TEMP XHR HOUR XMIN MINUTE 170 IF TEMP lt MIN THEN MIN TEMP NHR HOUR NMIN MINUTE 188 N 1 DTEMP TEMP DHR HOUR DMIN MINUTE GOSUB 238 198
35. ana log monitor is purchased and added to the system Generally a multisync monitor like the NEC MultiSync is required for extended mode 800 by 600 graph ics However at least one VGA board the Tecmar VGA AD see The Tecmar VG AD box else where in this article can display ex tended mode graphics on an EGA or VGA monitor using interlace scan ning Ininterlace scanning the moni tor doubles the resolution of the dis play by first writing one image on the screen and then going back and fill ing in the blank spaces between the lines with another image in an inter woven pattern This is similar to but different from the double scanning Continued on page 90 May 1989 MODERN ELECTRONICS 21 Project The SunGuard This compact device keeps tabs on cumulative ultraviolet energy detected over a period of time and sounds an alert when the total exceeds a preset limit for safe tanning By Anthony J Caristi ith summer almost here millions of us will soon be flocking to the beach where we ll bask in the sunlight Summer sun can be very beneficial but too much of a good thing can also be dangerous to your health from painful sunburn to more serious sun exposure related ailments The amount of sunlight that will not cause harm varies from person to person But even if you know your tolerance level it is sometimes diffi cult to judge a safe exposure time when the sky is overcast or partly
36. and pin 5 of the tens counter goes high both counters are reset At this point the process repeats itself for as long as ac line power is applied to the clock Note in Fig 1 B resistor R3 con nected between output pin 5 and RESET pin 15 and SECONDS HOLD switch S connected between pin 15 and the V bus As the name of S7 implies this is the hold circuit that allows you to adjust your clock s time keeping to single second accuracy The set circuit for the minutes counter is a set reset SR flip flop made up of NOR gates C2C and IC2D with IC2C being the set side and C2D being the reset side The output pulse at pin 5 of C4 is fed to the pin 8 set input of C2C Nor mally open pushbutton MINUTES SET switch S2 in Fig 1 A is also con nected to pin 8 of C2C while the fast set pulses from pin 12 of JC 4B are fed to the reset side of the SR flip flop at pin 12 of JC2D The pulses from the seconds counter are much narrower than are the fast set pulses Since the fast set is constantly occurring the output at pin 11 of JC2D is kept low When a pulse from the seconds counter oc curs the output at pin 10 of C2C is forced low which forces the pin 11 output of C2D high until the arrival of the fast set pulse resets the flip flop This advances the next counter with a pulse whose width is one half the fast set period To advance the counter at the fast set rate MINUTES SET switch S2 must be pressed Doing this
37. at And who knows maybe one of vour composi tionscan use something that sounds likea cat being mugged by a chicken there real ly is a sound like that in here but I forgot to write down the number or maybe my old Fender Princeton amp was in the pro cess of losing a 6L6GC Along with the above sound though there are some truly terrific ones If you re a fan of 60 s rock you ll remem ber how many of those groups used Ham mond B 3 organs Patch 964 turned my little Casio MT 540 into a great sounding B 3 And toggling up one patch 965 added a great Leslie effect Does anyone other than me even remember those big old Hammond B 3 organs with the exter nal Leslie rotating speakers The Ma trix 1000 also has a great VOX organ patch the VOX was used by most of the British groups of the 60s Whilethe first 400 or so patches Banks 0 1 2 and 3 are a mixed bag the other banks are a bit more segregated Bank 4 is Woodwinds and Horns Bank 5 is Horns and Leads Bank 6 is Strings Bank 7 is Basses Bank 8is FX effects and Percus sion and Bank 9 is Keyboards The first 200 patches Banks 1 and 2 on the Ma trix 1000 can be overwritten This is use ful if there are a number of sounds in there that will never be used you can move sounds from the other banks into their place The synthesizer functions inside the M 1000 can also be accessed so that you can make up your own patches or modify the existing ones Opcode S
38. back one hour in the spring and fall simply press and hold the SECONDS HOLD button as you advance the hours indication to the proper hour Then set the min utes display one minute ahead Re lease the SECONDS HOLD button at the exact second to start the new minute ME Say You Saw It In Modern Electronics HITACHI SCOPES 4M DISCOUNT PRICES V 212 DC to 100MHz Dual Channel Delayed Sweep CRT Readout Sweep Time Autoranging N V 425 R _e Trigger Lock List 560 List 995 List 1595 1 325 amv Sensitivity Save 141 us SAVE 20M H2 1mWV sens Delayed Sweer DC Offset Ver Mode Trigger 75 20MHz Dual Trace Oscilloscope L 40MH2 Y 1mV sens DC Offse Ver Mode Trigger Alt Mag 1 75 150 All Hitachi scopes Include probes schematics i Bre Seashe uer cm Weis un des ia and Hitachi s 3 year guaranty on parts and SOMH 2mwv sana Delayed Sweep CAT Readout 1 195 170 100 H2 2mV sens Delayed Sweep CRT Reacoul Cursor Meas 1895 225 labor Many accessories avaiiable for all scopes DC to 40MHz Dual Channel CRT Readout Cursor Meas DC Offset Alt Magnitier Compact Size V 1100A 100M H2 imV sens Delayed Sweep CRT Readout DVM Counter 1mV sens Delayed Sweep Cursor Meas DYM Counter e 295 250 V 1150 150MHz 100 535 495 M0 1252 High luminance 6 CRT imV Sensitivity EKV Acceleration Voltage Wns Rise Time Operation Z Axis Delayed Triggering
39. carbon resistors do not have the value stability required for this part of the circuit Resistor R is specified at 0 2 ohm which is not a readily available value However it is easy to make the re quired value resistor from enameled magnet wire and a resistor The Wire Length Chart specifies lengths of wires of various gauges that can be used to fabricate this resistor Cut the wire whose gauge you have chosen to the length specified for it in the Chart Then scrape inch of enamel insulation from each end Now wind 4 inch of one end of the magnet wire onto the bare lead of any V watt resistor that has a medium to high resistance value Start near the body of the resistor Solder this wire end into place Then wind the entire length of wire except for the last inch onto the body of the resistor It does not matter if you wind in a ran dom fashion and end up with more than one layer Wind the remaining bare portion onto the resistor wire opposite the soldered end and solder it in place Paint a smooth layer of coil dope or a fast setting epoxy cement over the coil to hold the windings in place M a c Time Delay Range for 1C2 Outputs Length in Inches Output Time Delay Pin Minimum Maximum 6 15 seconds 52 seconds l 8 minutes 28 minutes 2 16 minutes 56 minutes 3 32 minutes 112 minutes After the coil dope has dried or the epoxy cement has set plug the leads of th
40. causes C2D to behave like an inverter that passes the fast set pulses to the next count er The hours set circuit is operated in exactly the same manner as is the minutes set counter this time using the SR flip flop made up of C9C and JC9D and HOURS SET switch 5S3 The set and reset sides of this SR flip flop are C9C and IC9D respectively Last but not least is the hours counter which is depicted schemati cally in Fig 1 D The counter is made up of decade counter C 0 and quad NOR gate C11 The SR flip flop for this circuit is made up of IC11B set and C11A reset The other two C1 gates are employed as inverting buffers on the flip flop s outputs Output 9 at pin 11 of ZC10 con nects to the pin 6 set input of C11B and output 2 at pin 4 of C10 goes to the pin 1 reset input of C11A The output of the flip flop at pin 10 of IC11C goes through isolation diode D19 to hours LEDs 2 through 10 o clock and the output at pin 11 of ICID goes through isolation diode D20 to hours LEDs 1 11 and 12 o clock Assume that decade counter C 0 is reset and C11B is low and the hours counter is begun to be ad vanced When the 2 output at pin 4 of IC10 goes high the output of C11B at pin 4 is forced high in turn forcing a pulse to go to RESET input pin 15 of ICIO via the integrator made up of C2 and R6 Now the 0 output at pin 3 of ICIO goes high again but the hours LEDs for 2 through 10 o clock have been selected thereb
41. circuits including those that use microprocessors optical isolators phototransistors and other fairly new devices Diagrams line art and checklists accompany the text to simplify diagnoses of problems and speed the reader in troubleshooting a de fective circuit The book is divided into 10 sections each of which deals with tests for a specif ic range of electronic circuits Section 1 for example deals with audio equipment and covers some 20 tests that can be made on it In section 2 the reader is given im portant information on maintaining digi tal equipment Section 3 provides practi cal guidance for solid state circuit and de vice servicing Radio frequency circuits are covered in Section 4 Then Sections 5 W NEW LITERATURE Product Line Catalog Contained within the latest 74 page product line catalog from Jameco are listings and full descrip tions for a wide range of items ranging from computer kits and IBM Apple compatible peripherals to individual inte grated circuits Among thenew itemsthat have been added to this 1989 catalog are 16 and 20 MHz AMI 80386 mother boards and the new NEAT New En hanced AT motherboard A welcome feature is a two page insert of TTL and microprocessor pinout data For a free copy write to Jameco Electronics Shoreway Rd Dept ME Belmont CA 94002 Direct Purchase Catalog A new catalog from Tektronix provides information test instrument buyers need to make di rect pur
42. cloudy You must also consider that thetime of day and even month of the year determine how intense the sun light will be This is a lot to keep in mind but SunGuard remembers it all effortlessly to help you stay healthy as you enjoy the sun SunGuard s sensing element accu rately measures sun intensity A built in memory circuit integrates measured intensity over a period of time and totals the cumulative expo suretothesun srays Whena safe ex posure limit is reached which you set beforehand a piezoelectric buzzer sounds to alert you to either turn over Or cover up SunGuard s solar cell sensor re sponds to ultraviolet energy This makes the project immune to false measurements that might otherwise occur from passing clouds or hazy sunshine that can give the appear ance that the UV energy is less intense than it really is This is important be a N E a oU o eee EES cause it is UV energy which pene trates clouds that causes tanning and burning About the Circuit The sensing element used in Sun Guard produces an output that is di rectly proportional to the intensity of the detected ultraviolet energy from the sun This controls the rate of a built in clock that counts the number of minutes of relative exposure With the way the circuit is designed the warning signal will be generated at the desired amount of exposure whe ther the sun is shining through a clear sky intermittent cloudiness or
43. computer brand pre ference rose to 10 4 from 4 4 while Apple II type computers dropped to 4 4 from 1986 s choice by 7 Apple Computer s product total therefore in creased by 3 4 in brand preference buying among Modern Electronics subscribers The 1989 Study demonstrates how much Commodore 64 and 128 models dipped among readers preferences with only 2 choosing it among respondents saying they plan to buy a computer as compared to 1986 s 21 9 Based on 89 results M E readers also will be heavily involved in upgrading their computers For example 50 19 o noted that they plan to add a hard disk drive in the next 12 months as compared to 1986 s 14 29 1 say they ll be add ing a modem while 14 9 said the same three years ago 27 3 for a color moni tor while 11 7 of 86 readers noted this addition coming up Laser printers were pinpointed for buying soon by 23 of re spondents while in 1986 all printer types expected to be purchased amounted to 13 9 Asked whether computers to be pur chased will be used mostly for business professional or personal applications 38 chose business professional whereas 46 8 had made this choice in 86 What caused this change one might wonder I believe the increase in personal use of computers is due to a few cogent reasons substantially lower selling prices of IBM clones which at the same time are much more powerful than the old Commodore and Atari 8 bit machines Furt
44. configurations use relays with more contacts and or more relays rangement This configuration pro vides redundancy for the circuit When the electrical device whose operation is to be sensed is turned on current flows from the negative terminal of RECT through the two parallel sets of series connected di odes to the positive terminal and then through the operating device to circuit ground Each diode has a for 50 MODERN ELECTRONICS May 1989 ward voltage drop of approximately 0 7 volt Thus the potential generated from positive to negative terminals of RECT is roughly 1 4 volts when the monitored device is turned on For this application RECT must have a peak inverse voltage PIV rating of at least 20 volts and a cur rent rating that is at least equal to the peak current plus 20 percent or so of Say You Saw It In Modern Electronics Power antenna down NORMALLY CLOSED fuse block accessory Power antenna 12V up COMMON 12V Smart Car Relay Power antenna NORMALLY OPEN 12V on audio unit GROUND Fig 2 Typical wiring instructions for using project to control deployment and retraction of an electrically operated radio antenna the device being monitored and con trolled For the original prototype selected a 5S0 PIV 25 ampere bridge rectifier assembly which was deemed adequate for just about any sense control application I was likely to encounter The
45. distance of 1 inches at the free end and slip l inch lengths of small di ameter or insulating plastic tubing over the ends of both LED wires Identify and clip the cathode lead of the LED toa length of inch Forma small hook in the remaining lead stub and crimp and solder this to the black insulated cathode wire Do the same with the LED s anode lead and red insulated anode wire Push the tubing up over the connections until it is flush against the bottom of the LED s case Shrink into place With the telephone instrument s cover removed see Fig 3 find the points in the circuitry to which the in coming red and green insulated tele phone line conductors connect Plug the instrument s cord into the wall jack Holding the hookswitch down use a multimeter set to the dc volts function and a 100 volt full scale range to take a reading across the in coming telephone line Connect the meter s hot and common probes to the line s red and green insulated conductors respectively as you take this reading If you obtain a reading of 48 volts or so the lineis wired correctly If your reading is 48 volts or so the line is wired backward It is much more important to observe polarity that to match insulation colors when connecting the project to the tele phone line If you connect the project in reverse polarity across the tele phone line the hold function will not work Once you know the polarity of the telephone li
46. exit holes for the wires with small rubber grommets If you EE cR TT I Ju ED are using a plastic enclosure drill the lead exit holes through the plastic walls and forget using grommets Tie a strain relieving knot in each wire that exits the enclosure inside the enclosure and with about 1 inch of slack Mount the circuit board as sembly in place using inch spacers 4 40 or 6 32 x inch machine screws lockwashers and nuts Then thread the free ends of the wires through the holes drilled for them and label each according to the legends detailed in Fig 2 If you are using a dry transfer lettering kit pro tect the lettering with two or more light coats of clear spray acrylic Al low each coat to dry before spraying on the next When wiring the project into your vehicle s electrical system take par ticular care with the sections that car ry heavy current Make sure you pro vide adequate insulation and that all connections are both mechanically and electrically secure before solder 52 MODERN ELECTRONICS May 1989 ing them Double check all wiring to make certain that you assembled the circuit correctly Decide where in your vehicle you are going to mount the project Select a location very near the device whose operation is to be monitored and controlled Resiliently mount the project in the selected location To do this drill two holes in the vehicle s chassis work the same distance apart as those you drilled
47. for project mounting in the enclosure Make these holes slightly smaller than the panhead sheetmetal screws you will be used for mounting purposes Place a suitable flat washer on each of two No 6 or No 8sheetmetal screws and follow with a small rub ber grommet Plug the ends of the screws into the mounting holes drilled in the floor of the enclosure and fol low with a small rubber grommet on the end of each screw Then drive the screws into the holes you drilled in the vehicle s chassis work Fasten the Say You Saw It In Modern Electronics 12V fuse block accessory 12V INPUT COMMON No 1 Sman Car NORMALLY Relay OPEN Rear left 4 NORMALLY No 1 K2 SLOSED Front right 4 No 1 12V 12V K1 K2 audio unit audio unit 12Vdc 12Vdc vl No 1 No 2 aux relay aux relay Front right No 1 K1 LEGEND E iru e Normally open l f Normally cicsed Rear right 4 No 1 K2 K Front left 4 No 1 Front left No 1 K1 K2 Rear left 4 K1 K2 K1 Front left No 2 Front left speaker Front left K1 No 2 K2 Rear left No 2 Rear left speaker Rear left K2 No 2 K1 Front right No 2 Front right speaker Front right K1 No 2 K2 Rear right No 2 Rear right speaker Re
48. have a vertical signal output connector on the rear panel You can directly con nect the counter s input to it to give you a frequency readout of the wave form being displayed on the scope Only high priced scopes have accur ate frequency readouts which you can match for a modest investment cited some frequency counter connection caveats earlier warning about the dangers of direct connec tion in some instances There are ways around this though For exam ple what if you really had to know the frequency of the current coming out of a wall tap One way to circum vent destroying the instrument by taking a frontal connection attack and possibly exposing yourself to an electrical shock because the portable counter will be grounded through your hand is to use a low voltage SSS IECIT MGE OM VEN S SUC M NN ec RNV XC Ea SIGNAL TAP METAL ENCLOSURE FROM TRANSMITTER TO ANTENNA OR LINEAR PL 269 CONNECTOR 10 PF 100 vOLT OrsK CAPACITOR FEMALE BNC CONNECTOR TO FREQUENCY COUNTER Fig 1 Details of a tap arrangement for safely counting the frequency at the out put of a radio transmitter transformer to step down voltagetoa tolerable level and to isolate the pow er line Note that the subject portable counter must be set to its A range even here to avoid damage You can measure a transmitter s output frequency by using some keen coupling techniques that avoid a Straight connection
49. in the various lo cations If you elect to use perfor ated board construction use Fig 3 as a general layout guide and make sure to keep the wiring between PC RI R2and CI as close as possible to that shown in Fig 3 since the op amp operates on a very small input volt age produced by the solar cell and A7 Begin wiring the board by install ing and soldering into place the IC sockets This done install and solder into place the resistors and potentio meters followed by the diodes and capacitors Make certain that diodes DI and D2 and electrolytic capaci tors C and C2 are properly polar ized before soldering their leads into place Install the transistors in their respective locations and double check their basing before soldering their leads to the copper pads on the bottom of the board When assembling the pc board do not mount the solar cell or remove it May 1989 MODERN ELECTRONICS 25 Wire Length Chart for R1 Wire Size 28 38 30 24 32 155 34 1074 36 M4 from its protective package until in structed to do so later This compo nent is extremely fragile and is easily damaged by careless handling Be sure to use the components spe cified in the Parts List for R2 R3 and R6 The values of these metal film re sistors which remain relatively sta ble as the temperature changes de termine calibration accuracy which is something you do not want to change once you have calibrated the project Ordinary
50. it in a separ ate box and connect it to the tele phone line via a cable equipped with a modular connector this is an FCC requirement for all telephone acces sory devices Wherever you mount the circuit board assembly make certain that you insulate its bottom from any May 1989 MODERN ELECTRONICS 47 Fig 2 Actual size etching and drilling guide A for fabricating a printed cir cuit board for the project No board outline is shown because the dimensions of the board you actually use will depend on available space and mounting condi tions inside a particular telephone instrument Wiring details B for on and off board components for pc board Use this as a guide to mounting components and wiring them together if you use perforated board instead of a printed circuit board metal or other parts of the telephone instrument One way to assure this is to use thick double sided foam tape as the mounting medium rather than machine hardware Once the circuit board assembly is mounted drill holes for mounting the switch and LED on the instru ment s case where they will be readily visible and accessible Examples of typical locations for these holes are shown in the lead photo Mount the switch in its hole and use a panel clip or small rubber grommet to mount the LED Crimp and solder the free ends of the S1 wires coming from the circuit board assembly to the lugs of the switch Then untwist the LED wires a
51. jack Pick up the handset and press the HOLD button you installed and note that the LED lights While continuing to press the HOLD button return the instru ment s handset to its cradle and re lease the button The LED should re main lit when you release the button At this point picking up the handset Say You Saw It In Modern Electronics Fig 3 Interior view of disassembled telephone instrument with dial assembly re moved to permit project to be mounted on floor and LED and switch on dial bezel Other instruments offer different mounting locations should cause the LED to extinguish and the telephone line to return to its normal off hook condition If the LED does not light at all check to make sure you connected the circuit to the telephone line in the proper polarity If so the LED may be installed in the wrong polarity or it might be defective Whichever the case either correct your wiring or re place the LED If the LED turned on but did not remain lit after you replaced the hand set in its cradle and released the HOLD button in that order the value of R7 is probably too high for your particu lar phone line Solve this problem by replacing R7 with a resistor of lower value Both 1 200 and 1 300 ohm 5 percent tolerance resistors are avail able with the former being more common Just keep in mind that you should generally use the highest value of resistance for R that permits reli able operation
52. line between it and the counter For example you might use the signal tap illustrated in Fig 1 The design has to be approxi mated because the transmission fre quency and power level will affect operation As a result some inser tion loss might be incurred There are more ways to skin the cat of course You can use adequate attenuators to reduce the power level to asafe level for the counter s input for instance Some much costlier fre quency counters even have built in switchable attenuators Keep in mind that testing a trans mitter without using a non radiating dummy load can interfere with the radio communications of others who are active on the same frequency Also remember that counters mea sure steady radio frequency energy such as a continuous carrier wave The instrument is not designed to work with an audio modulated carri er much as Morse Code isn t This might seem to indicate that you can not count the output of a single side band transmitter since audio has to be used to generate it 34 MODERN ELECTRONICS May 1989 You can get around this however because some SSB transmitters have carrier insertion provisions What if yours doesn t Well old timers say you can simply send a single tone whose frequency is known through the microphone According to them then count the output taking care that you do not do so with a direct connection and subtract or add the single tone s frequency depending
53. of supply as compared to only 27 4 three years ago This seems to parallel the rise in readers who are technicians These figures represent a fragile rela tionship between editorial matter and reader Just because more than 1 3rd work in the maintenance repair field doesn t mean that we ll shift editorial gears and focus on it Nor does the fact that another 1 3rd are professional elec tronic design or development engineers or technicians mean that that s what we ll emphasize There are specialized professional and trade publications that do just this Modern Electronics however straddles the entire field of electronics broadening the technical and industry knowledge of readers who in their day to day work and professional journal reading tend to become very specialized We ll continue to do this as your one stop source of electronics and computer information helping you to continually hone your technical competence as new developments are introduced Thanks for your support and loyalty Say You Saw It In Modern Electronics W BOOKS I Electronic Servicing Data and Proce dures by Robert C Genn jr Prentice Hall Soft cover 373 pages 16 95 This book is written to be used right at the service bench It details how to con duct nearly 200 tests and measurements on virtually every type of electronic equipment one is likely to encounter Step by step procedures are given for testing both analog and digital
54. of the hold circuit If the LED remains lit all the time no matter what you do with the HOLD switch and handset look for a shorted SCR shorted HOLD switch or a short circuit on the circuit board or in your Say You Saw It In Modern Electronics wiring related to these components In any case rectify the problem be fore attempting to put the project in to service This hold function is extremely easy to use Whenever you wish to place a call on hold simply press the HOLD button and continue to do so until you have hung up the handset You then release the HOLD button to keep the telephone line on hold Picking up the handset of the in strument in which the hold function circuit is installed or any other instru ment connected to the same tele phone line automatically reinstates the two way connection A bonus offered by this implemen tation of the hold function is that you can activate it to place a busy sig nal on the line to prevent calls from getting through when you do not want to be bothered To activate the busy signal simply press the hold button while leaving the handset in its cradle The LED will light and any caller who dials your number will get a busy signal To deactivate this function all you have to do is lift the receiver from the cradle ME CAYSTALS SINCE 1965 THE ONLY SOURCE YOU LL EVER NEED SATISFACTION GUARANTEED QUICK SHIPMENT LOW COST RELIABILITY
55. of the suc cinct user s manual will point out that the Search option in the main menu will lo cate the unit directly for you With the foregoing easily taken care of and removing display of some classes that l ll never use the conversion program worked like a charm as a resident pro gram Along with my spelling checker ef al it s nice to have it ready for the asking It s interesting too to see that there are nine different types of miles two types of standards for amperes and soon ME CIRCLE NO 131 ON FREE INFORMATION CARD Total Price Freight Prepaid in AM FM Wide FM modes Express Shipping Optional Covers 5MHz to 2000MHz Continuous coverage i Nm nc 2000 Channel Memor 1984 Scan n 360 00 amp 16 Search Groups Scar Search speeds up to 36 channels ot incre ments per second Built in RS 232 computer interface 25 Day Satisfaction Guarantee Full Refur d if not Satisfied Size 3 H x 5 Wx TD Wt 21b 100 Supplied with AC amp DC power cords Telescopic antenna COMMUNICATIONS 10707 E 106th St Indpls IN 46256 mm Toll Free 800 445 7717 Visa and MasterCard COD slightly higher In Indiana 317 849 2570 Collect FAX 3 7 849 8794 CIRCLE NO 111 ON FREE INFORMATION CARD LETTERS from page 9 was added with Version 3 and I missed seeing it in the documentation Having used PageMaker several times a week over the last two years I am en thusiastic about it but I re
56. precision reference di ode C14 provides a stable 1 2 volt reference at pin 9 of C12 The poten tial at pin 9 is half the voltage that causes a full scale output on the ADC That is a 2 4 volt input which is twice the reference voltage causes an output of 11111111 at ADo through AD7 of C12 This gives the ADC a resolution of a little less than 10 milli volts which translates into 1 degree Fahrenheit per bit Measurement range of the Temp watch depends partly on the version of chip used for C13 The LM34C for example is accurate over a range of 40 to 230 degrees Fahrenheit Say You Saw It In Modern Electronics 1C12 ADC0804 Analog ground Power supply ground LM385 1 2 LM34 and LM385 1 2 BOTTOM VIEW Fig 5 Schematic diagram for the temperature sensor and A D converter cir cuitry that connect to the Microsys though the Tempwatch measures only down to zero degrees The LM34D on the other hand has a narrower range of 32 to 212 de grees Fahrenheit as well as a lower price to match so it may be a better choice if this range suits your needs A separate ground return for ana log signals in the sensing circuit helps to reduce noise which improves measuring accuracy Ground con nections for 7C13 IC14 and C21 connect to JC 2 s analog ground at pin 8 A single ground wire then con nects pin 8 directly to ground on 5 volt regulator CJ The eight data lines on C 2 pins 11
57. rhythm accompaniment You can change the particular instrument sound you re playing and most of thein struments supplied by Creative Labs sound quite good C MS even has a utili ty that lets you create your own instru ments by altering the basic components harmonic content attack duration and delay I did however find composing with the C MS time consuming tedious and not very intuitive There aretwo methods you can use and both of them involve us ing a word processor or text edit in ASCII text mode to input multiple lines of num bers Adding the automatic chord bass rhythm accompaniment is a similar pro cess I didn t play with this feature very much I ve probably been spoiled by the title The Trout Composer edited by WH Sim message by Schubert Enter by Jessie Tan ml m2 m3 m4 m5 p 3 p 4 p 4 p 3 p 3 p 4 x b p 13 V 180 dP dP dP dP dP dP dP dP 1 1 33 1 5 5 67 1 1 11 5 67 1 05 05 05 05 03 03 03 03 1 1 33 1 5 13 11 1 D s 120 x b t 2 4 p 16 5 5 2 71 7 76 7 3 TALULA AAT _72 34 73 2 1 2 11 05 05 02 02 20 Aug 87 5 5 5 5 2 1 _16 5 5 _72 34 07 12 07 12 10 50 30 10 20 _50 5 0 ooToojoo oo 1 1 7 33 7 1 5 1 1 1 7 33 1 759417 3 11 5 67 1 S 1 11 5 67 1 5 03 03 0 3 03 02 02 3 6 2 31 84 5 S 72 6 1
58. some form of compensation to adjust for nonlinearity is usually required I recently purchased a chart recorder an instrument I have long needed for monitoring various atmospheric and sol ar phenomena A chart recorder is ideal RELEASE CURRENT mA MINUTES for observing the behavior of a thermis tor Figure 2 is based on a chart recording I made by connecting a tiny bead thermis tor in series with the current input of a re corder The thermistor had a room tem perature resistance of 2 000 ohms When I touched the thermistor with my index finger the current flowing through it increased from almost nothing to 250 microamperes in just a few seconds Af ter 25 seconds or so the current peaked at about 350 microamperes When I re moved by finger the current flow fell back to a negligible value after around 90 seconds How Thermistors are Made The active element of a thermistor is a semiconducting ceramic that is made from the powdered oxide of a metal like nickel copper magnesium iron titan ium or manganese Each metal gives a different resistance range The first step in manufacturing a ther mistor is to mix the powdered metallic ox ide with a binder to form a paste Bead thermistors are made by depositing a tiny dollop of semiconductor paste at inter vals along two closely spaced platinum alloy wires The wires and beads of paste are then heated in a furnace which action sinters the paste and bonds
59. songs if you play them on a high speed computer since they re designed for 4 7 MHz PCs ne Products Mentioned Matrix 1000 Oberheim 2015 Davie Ave Commerce CA 90091 Matrix 1000 Editor Librarian Opcode Systems 1024 Hamilton Ct Menlo Park CA 94025 415 321 8977 Matrix 1000 Graphic Editor Librarian Dr T s Music Software Inc 220 Boylston St Ste 306 Chestnut Hill M A 02167 617 244 6954 Creative Music System C MS Creative Labs Inc 2363 Greendale Dr 5 san Francisco CA 94080 415 878 2874 CL E MEN MUR Tempe mccum crc RC RIS H n E Q s T i 80 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics W SOFTWARE FOCUS Converting Celsius to Fahrenheit etc By Art Salsberg S I Plus Ver 1 0 is a PC program for converting numbers from one unit sys tem to another in the International Sys tem of Units This might be changing a Celsius reading to Fahrenheit meters to feet etc It s for use with IBM compati ble PCs and requires 160K memory The package consists of a 5 non copy pro tected disk and a user s manual S I Plus is priced at 79 from Geocomp Corp 66 Commonwealth Ave Concord MA 01742 If you re involved in a technical area where a variety of unit conversions are often made the S I Plus program can give you an almost instantaneous conver sion number from about 70 000 different conversions it contains Conversi
60. sun s rays Thereafter when the alarm sounds you have had your specified amount of sun Keep in mind that SunGuard s clock will almost always run slower than your watch does be cause the sun s intensity will usually be less than maximum and is likely to vary during a sunbathing session 84 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics Making It Count from page 37 because they are getting better and cheaper Nevertheless there are still some counting chores that they can not normally handle without elabor ate circuit support So don t expect to check out the crystal oscillator in your wrist watch with any moderately priced counter Its micro power operating level is too low Nor would you normally be able to count a radio control signal that s pulse modulated Some garage door remote control openers use this sys tem so do model radio control cars boats and planes And infrared sig nals such as used by remote control circuits for TV VCR and compact disc applications cannot be counted You cannot expect to be able to count signals that aren t continuous for at least as long as a counter s shortest gate period either Natural ly There are more costly bench type Counter Kit Information The following items are available from Optoelectronics Inc 5821 N E 14 Ave Ft Lauderdale FL 33334 800 327 5812 in Florida 305 771 2050 A kit of all components but not including enclosure
61. tax With increasing sunlight intensity C7 charges faster and with less intensity it charges slower Also greater val ues of resistance result in slower charging and lesser values speed up the charging rate Programming of Q is accom plished with a voltage about 1 4 volts fed to its gate which is pro vided by the series connected for ward biased D D2 silicon diode pair The forward biasing voltage is delivered from the circuit s positive supply bus through R7 The voltage fed to the gate of Q will remain es sentially constant as the terminal voltage of the battery falls with use The anode of Q is connected to the positive side of the charging capa citor C7 When the voltage across the 24 MODERN ELECTRONICS May 1989 capacitor exceeds the programmed 1 4 volt potential at the gate of QJ the transistor suddenly triggers into conduction and dumps most of the charge stored in the capacitor into R8 Asa result the voltage across C7 falls to near zero at which point the capacitor begins charging again to re peat the cycle As you can see the frequency of oscillation of Q is proportional to the charging rate of C7 which in turn is a function of the intensity of sunlight striking the solar cell An in crease in sunlight intensity causes the frequency of the signal generated by the Q7 oscillator to increase and vice versa TIME potentiometer R5 also controls theoperating frequency of the oscillator a
62. their battery connectors type PROG do not type the quotation marks in this or any other instruction to key in a com mand and the Microsys will pro gram the EPROM with the program currently in RAM An additional command allows you to configure Tempwatch to begin running imme diately upon power up which frees you from having to connect to the terminal at all to use the Tempwatch To provide this capability type PROG2 This command is re quired in addition to the PROG command that saved the program It causes the 8052 to run Program 400 X sPORT1 4 INT PORT1 4 4160 IF X 1 THEN GOSUB 458 420 IF X 2 THEN GOSUB 736 430 NEXT I 440 RETURN 1 in the EPROM immediately on power up Now you can power down the Tempwatch disconnect it from the terminal and move it to a new loca tion When you power up again the Tempwatch program runs auto matically There are plenty of enhancements in both the hardware and the soft ware areas that you can add to the Tempwatch For example you could add a temperature alarm or a pro gram that measures and stores the temperatures at a particular time of day Or you can turn your Microsys into something else such as an in strument to measure sound or light to control relays or to monitor or control whatever real world condi tions or devices you wish The great appeal of the Microsys is that you are ultimately in control By adding appropriate inputs outputs and programs
63. to play back scenes in forward or reverse at nor mal speed while operating in either camera or VTR mode so that new scenes can be inserted over old ones Edit Search allows the user to review a scene just recorded while Scene Search provides high speed ac cess to any scene on thetape Record ing review quickly confirms the last few seconds of a just recorded se quence The Edit switch reduces sig nal loss during editing The flying erase head completely erases the sig nal at the beginning and end of a scene for clean recordings Power for the camcorder can be provided by a rechargeable Ni Cd battery an ac adapter battery charg er or a separate lithium battery The compact camcorder weighs 2 6 pounds without battery CIRCLE 30 ON FREE INFORMATION CARD Computer Trackball Fulcrum Computer Products Healdsburg CA high resolution Trackball Plus cursor pointing alter native to the mouse interfaces to IBM PC and compatible computers and many CAD CAM environments via a standard RS 232 serial port Ball motion is optically detected and transformed into one of many for mats by a local microprocessor be fore being sent to the computer Claimed to be easier to use and more reliable than a mouse Trackball Plus emulates both Microsoft Mouse and Mouse Systems Mouse as well as popular digitizers like Summagraph ics Bit Pad One In all eight popular pointing devices are emulated Trackball Plus re
64. to publisher approval WTT 20 Is only about the size of a dime yet transmits Mailing Information Copy must be received by the publisher by the 25th of the third both sides of a telephone conversation to any FM radio E NM with crystal clarity Completely automatic Uses power 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 from the telephone line Itself never needs a battery Up to mile range Tunes from 70mhz 130mhz Easy to assembie kit includes all parts and instructions On ly 29 98 tax inci Call or send 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 ailow 21 days DECO INDUSTRIES BOX 607 BEDFORD HILLS NY 10507 914 232 3878 CIRCLE NO 105 ON FREE INFORMATION CARD CABLE T V CONVERTERS WHY PAY A HIGH MONTHLY FEE All Jerrold Oak Hamlin Ze nith Scientific Atlanta Mag navox and all specialized cable equipment available for ship ment within 24 hours For fast service MC VISA or C O D tele phone orders accepted 800 648 3030 60 Day Warranty Quantity Discounts 8 A M to 5 P M Monday through Friday Central Time Stamp Envelope 60 postage for FREE Catalog Mi
65. to remove any bridges When you are satisfied that the cir cuit board assembly has been prop erly wired place the solar cell on the board Very carefully remove it from its protective package Note that one side has a series of lines stopping short at each end leaving a clear strip about 4 inch wide This is the neg ative terminal of the cell The back side is the positive terminal Scrape X inch of insulation from one end of two 2 inch lengths of enamel insulated magnet wire not Say You Saw It In Modern Electronics 25 50 100 Fig 4 Actual size artwork for cali brating potentiometer control heavier than 24 gauge Use a low wattage iron to carefully solder the stripped ends to the clear portion on the front of the solar cell and the back of the cell Place the solar cell with its front or negative side up in the indicated location on the circuit board assem bly and trim the two magnet wires to proper length Carefully scrape away about X inch of insulation from the free end of each Then insert the wires into the proper holes in the board making sure to observe cor rect polarity and solder into place Cut off any excess wire on the bot tom of the board Secure the solar cell to the top sur face of the board with a drop of sili cone or any other suitable adhesive Set the circuit board assembly in a safe place until the adhesive sets Tightly twist together the fine wires at the free ends o
66. turned on us ing a binary input number of 100 Yellow is created by blending red and green using the binary number 110 Using this approach which is similar to the way CGA drives its monitor Eight colors are possible with this ar rangement EGA goes a step further by includ ing an intensity bit as well as a color bit for each of the color guns So in stead of just on or off you can turn a gun off half on or full on This leads to creation of 64 possible colors but now six inputs are required to achieve this Thus as the number of colors increases so does the number of con trol lines required To match VGA s 256K color palette you would need a monitor with 18 color inputs With an analog monitor colors are represented by voltage levels rather than binary codes Each of the Say You Saw It In Modern Electronics Hewlett Packard HP VGA 445 Hewlett Packard Co Roseville Terminals Div 8020 Foothills Blvd Roseville CA 95678 916 786 8000 IBM PS 2 Display Adapter 595 IBM 900 King St Rye Brook NY 10573 800 IBM 2468 Orchid Designer VGA 545 Orchid Technology 45365 Northport Loop W Freemont CA 94538 414 683 0300 Paradise VGA Plus 399 Paradise VGA Plus 16 Card 499 Paradise VGA Professional 599 Paradise Systems Inc 99 S Hill Dr Brisbane CA 94005 415 960 3353 Quadram QuadRAM Spectra 549 Quadram Corp One Quad Way Norcross GA 30093 404 923 6666 three color gun
67. w 40 414 D o aC 4 amp 4 o 400 4 a0 4 d crum La f d amp 5 40 A 45 e 00 a 4 ab m P Um s sop 4p np Pa m sop Li aia an E rua an n e 4 Pai ee o e 125 99 Pa Mm io0 ER a Pa op p m amp wan es uo 00 et e 300 EU M ra oo ia Pd m d B M P4 E an E 1 Los Ls ur 4 e m n t A m 24 Pa ho 5 0 nei Ay a Paradai biwo Pree s m A gt E be mv uu uou I TEEN z e um a Ja P4126 Mm c 96 M23 e x as pd P4 EN Li 8 op 50s l 4774 6 pares owo o val 200 18 00 mo wem d 2 XD R 8 00 N o om 44 jJ r VD p x o imo d eu 44 Fe Oe x am io mo aa Ed me MR 14 Man zi t i9 M ra 2700 c 2140 je n e xxx oo P4 1xD gt amp 7 40 7 40 Dn e n 894 z MOD pt BH mow e e 1m 8 4 4700 pt 25 Be a d 100 8 94 4 D0 s I c 2 ae 2419 SIND 575 726 a me RO e R aa y amp Sh 5e Sm e pa anon a 40 a me cc t ano M12 a O00 gr 9 0 lt x N ts FAH 22000 le 5 a 3000 24 79 o 7000 a s a 2400 u a Paiss 0000D p 30 m x00 N 23 pan eum p 72 T2 o0 pa 24 1 29 Pax oa 100 40 t ae ms 1400 24 sa PANS n on 4D 4t am a010 woe 0 008 592 P420 20 1D e um au 3300 100 m am ood 4700 160 E e oma nD qo 19 uM am A 1 45 PY o4 uz A 2 m amp IC e 8t we t 3 j w z 29 sr oon 0 300 eo o IO M amp 00 n rx amp 00 08 4706 T o fr em P ees LL aon 6 0 to t om 5000 90 7x An 1 a000 42
68. your TV VCR and CATV Assd GDZ 143 11b 29 95 7enith cannot guarantee that the PCC will operate every model TV or VCR Recharge your NiCd batteries Assd BP 1234 4Ibs 17 95 Amber screen fish finder Assd MI 2020 6 lbs 244 95 d Accessories Transom Mount Transducer Assd MIA 2020 1 4 Ibs Through Hull Transducer Assd MIA 2020 2 6 Ibs 44 95 99 95 Full color fish finder Assd MI 2040 101bs 399 00 Portable weather computer travels in your shirt pocket Save over 15 on this compact weather instrument that goes with you hiking biking boating and camping Gives time date and current temperature plus keeps a record of highest and lowest temperatures Also acts as a stopwatch Automatic power down feature extends battery life Requires three AAA batteries not included Assd BW 100 11b Now only 24 95 Heathkit to order CALL TOLL FREE 1 800 253 0570 Use order code 216 079 EC dai Ee SO for credit card orders 24 hours a day Some items are closeouts All items are available in limited quantities Prices for some items were previously reduced For your free Heathkit catalog call 1 800 44 HEATH May 1989 MODERN ELECTRONICS 5 LEARN VCR CLEANING MAINTENANCE REPAIR EARN UP TO 1000 A WEEK WORKING PART TIME FROM YOUR OWN HOME Secrets Revealed NO Special Toots or gre J ol THE MONEY MAKING ap
69. 00 ohm value for R2 I used a 741 operational amplifier for a comparator only because it is inexpensive and readily available For very low stand by power consumption use a CMOS comparator or op amp For details about how to use these low power chips see the December 1988 Electronics Notebook column in this magazine As for Q7 any general purpose npn switching transistor should work fine The piezoelectric buzzer should be the type that includes a built in driver oscilla tor If its maximum operating potential is less than 9 volts reduce the potential de livered by the power supply accordingly Though the circuit shown in Fig 13 is configured as a low temperature alarm it can easily be modified to function as a high temperature alarm All that s neces sary is to reverse the input connections to the comparator The alarm will then sound when the thermistor s temperature exceeds the value set by adjusting R3 Going Further Applications for thermistors are limited only by your imagination Want to detect SEE TEXT FoR VALUES Fig 12 A Wheatstone bridge differential temperature sensor 76 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics Fig 13 Schematic diagram of a low temperature alarm circuit infrared sources with a thermistor If so use a parabolic reflector from a discarded flashlight as an infrared energy collector Use clay or hot melt adhesive to mount a bead thermi
70. 1 4 volts dropped across RECTI is coupled to the base of 2N3906 pnp transistor Q through current limiting resistor R Base current for the transistor is limited to 15 milliamperes by R7 The emitter of QI is tied to the V rail of the vehicle s electrical system while the collector is tied to ground through the coil of relay K7 The relay has a coil rating of 12 volts dc and a resist ance of 120 ohms or greater which limits the current through the transis tor to 100 milliamperes or less The current rating of the contacts of K must be at least 120 percent of the current normally drawn by the device being controlled A normally open contact of K can be used to en ergize auxiliary relays if additional contacts beyond those available on the relay chosen are required Diode D provides protection for QI from reverse voltage spikes de veloped by K when the collapsing electromagnetic field around its coil induces a bucking voltage in the coil Fuse F1 in series with the project and device being controlled is included to Say You Saw It In Modern Electronics provide a safety device against over current damage Its current rating like that of the relay s contacts and bridge rectifier must be at least 120 percent of the current normally drawn by the device being controlled Let us assume that you are going to use the project to automatically switch an in dash speaker from the output of an in dash mono radio to the output of
71. 10 R12 100 ac UC motor i eo 117Vac A D1 30V NOTE See text C7 0 1pF 400V May 1989 MODERN ELECTRONICS 31 PARTS LIST Semiconductors D1 30 volt diac C1 7808 fixed 8 volt regulator IC2 IC5 CD4093 quad 2 input NAND gate 1C3 4516 counter IC4 87C64 or similar EPROM IC6 4543 decoder IC7 CD4030 XOR gate IC8 thru IC11 MOC3010 or similar triac output optical isolator Q1 Triac see text Capacitors C1 C2 C4 C5 0 I uF 16 volt disc C3 2 2 uF 16 volt electrolytic C6 0 22 nF 400 volt disc C7 0 1 4F 400 volt disc gers on triac QJ When this occurs the motor begins to operate at its slowest speed Incrementing counter C3 by using SI to have the monostable oscillator pulse input pin 15 of 7C3 will cause the motor to operate at a faster speed depending upon which and how many of the optocouplers are triggered on For this to occur though DIRECTION switch 2 must be in its UP position Placing this switch in the DOWN position will have EPROM Program Converts Binary Code into BCD Code Hex Address Hex Data O 00 29 ta AA WN 0 l 2 3 4 5 6 7 8 9 A B C D E F Resistors 4 watt 5 tolerance R1 20 000 ohms R2 R4 200 000 ohms R3 1 megohm R5 R6 100 000 ohms R7 thru R10 470 ohms R11 thru R14 See text R12 100 ohms R13 500 000 ohm linear taper panel mount potentiometer Miscellaneous DISP1 LCD004
72. 294b 8 ences Mi WOT 5j z MHEN has m tc ag 009 a te eo MBO See a MNA ei c M TN A 74HCO0 NOM ec CMOS vC MO a S kan Ti MESA Fee p Trte MEN Dem 44 COUP 79 mee 786 D Serecaen oa vagas sy 74 2 MESA me b macom 739 ba XAR ne e 194 ai HN 7 liuc 1ga JA bv P uas oM Disce D uae a 2 MCN z pe as CNN 72 sapo Mz V 2194 RN UT F x22 K n X v en Du EL Aer C lbi v d 2 V POR 24 ta n P AROR d Ac s VOR ee P245 2524h4 ne A 782904 D INAS 7870054 p PNE a i an mi es 741 t mia 6 IN 4 a 20 9026 s a 2 3 HC Th a JC Haec 187 umm P3108 gt ancem Olinma 4 ISITIN nuncu g Sm 14133748 S9 ranim e Man 141 SEION 4 vi PSLI 1 kc MNT 6 d 9 PILSSSAN UN BC SITAN MIA gs HCI a i MEON Mrs MA 24996 95 uw Pina vs et ancagim BIN On a Lan Jav 2400 7 vers y A 74500 TTL Jas c2 5 a Pw AC j Jan 2428 AIL 45004 243 E Tinm 5 Mh ug 450 y ance M SON 3 40c251N E S08 B nc ob 14508 1 Hd C 205 79 f 450 3m ra czsam O 4M C 2066 AN rs P sa w IC bre OUnT a evum apply Me zi ND totlownng t gmt Alta wnting yi ur orc igt ai of the amp heage We pay peng and nwrance Mwdresses nthe S A Canada and Menn Mewar Canada ori Mee dy Ch der Master Cr ISA E AK Puerto Rico 218 681 6674 1 METAL OXIDE FILA AES STORS DISC CAPACI
73. 4 May 1989 MODERN ELECTRONICS 27 Technology AC Motor Speed Controller Setting speed of an ac motor with optical couplers By Ricardo Jiminez G re you looking for an ele gantly simple and low cost circuit for controlling the speed of an ac motor If so here is one you should look into It uses four A Ad B A1 C A2 D A3 A4 ENS ooo e ae az art pan oo 28 MODERN ELECTRONICS May 1989 and a binary counter optocouplers and a single binary counter as the speed control ele ments and features a decimal numer ic display as well About the Circuit The schematic diagram of the speed IC2 IC5 CD4093 iC7 CD4030 controller circuit is shown in Fig 1 This circuit controls the speed of ac motor M by changing the conduction angle of triac O At the heart of this circuit are optical couplers C8 through C which control triac Ol A resistive network made up of Say You Saw It In Modern Electronics R11 RI2 R13 and R14 controls the magnitude of the current that passes through diac D Hence the conduc tion angle depends upon the state of the four parallel R77 through R74 re sistors Four resistors give 16 possi ble steps making a 15 speed ac motor controller By adding more resistors optocouplers up down counters and EPROMSs it is possible to obtain 31 63 etc speeds from the circuit When the circuit is first powered up the R3 C3 network disables the
74. 5 zx P a 2 Peay 33000 34 40 7 54 ima a 4000 5 w m gw 94479 eno 2 3 0 08 e MOT oo ate ODON k 3 s 224 a3 100 x E 3059 BM me PAL 0 a j 0 1299 BM an 54413 120b 5 w sr oe gan mo 00 3 i 0 s 39 BM so Pa 400 90 soe Mo seo bas 9b 200 e 0 vg ey 2000 k 4 le et p i t og Psa 27000 8 e 12 2 P MO ERDOD o s T cm g ni Pad 4000 o m ap Wo T 39 35 31 dede ul bd de ed lh PLT it eats prem qp 6s IIIM Nod urb Bst Ratssx Ra e Bale dale dabai heheh PD e STER PANASONIC B SERIES 389822333 we vonocibedo _ IRSESESSESRESS sess varat 8gurstBE e PET PETITES at at tet ted X 265 xag LAT i CARBON FILM RESISTORS eda 474 gt 1 2 Wein vel a4 ee RRBZE RREA nati BBenur fi A ERE eT Resemlos A aegreirents ARM Se act of ta 73 sioned 9 E 1 64 LM x 7 ac n 41 5 ae 84 B a 5 3 2 Wart Reontor amp teqinenme A u MS A T 3 473 EUS32EBVRRSRESRE JE 88 BE 33 amp S amp 7 288 BERBR EFEBRRREEBEEBESSET SESEKEE RRES RP aa ye WIREWOUND REC RESISTORS Avalsbie B i 300 Wen 2889 Tome ary etarc rd aver vate o 75 WIF ter 10 wert he 5 fus 3 the Dep Koy part nort us Ss me 3 4 1 3 9 igo 2717 9 Wart Mote Ree
75. 640 x 480 VGA 12 Graphics 16 8 x 16 640 x 480 VGA 4 13 Graphics 256 8x8 320 x 200 VGA 5 Popular VGA Extended Modes Text 16 9 x 16 80 x 43 Text 16 9 x 16 80 x 60 Text 16 9 x 16 132 x 25 Text 16 9 x 16 132 x 28 Text 16 9 x 16 132 x 43 Text 16 9 x 16 132 x 60 Graphics 256 8 x 14 640 x 350 enhanced EGA Graphics 256 8 x 16 640 x 480 enhanced VGA Graphics 16 8 x 14 800 x 600 multisync monitor required 6 Graphics 256 8 x 14 800 x 600 Tseng VGA chip Graphics 16 8 x 16 1 024 x 768 Tseng VGA chip IBM 8514 monitor required 1 VGA color default text mode 2 CGA color graphics mode 3 EGA color graphics mode 4 VGA color graphics mode 5 MCGA color graphics mode 6 Proposed VESA color graphics mode Enhanced from EGA Enhanced modes to 17 flavors from which to choose The 640 by 480 mode is the hot new graphics mode for VGA It can support up to 16 simultaneous 18 MODERN ELECTRONICS May 1989 colors and draws from a palette of 256K 262 144 colors Users who have a large appetite for color usage will relish the 256 color Say You Saw It In Modern Electronics screens of VGA s MultiColor Graph ics Adapter MCGA mode which supports a 320 by 200 graphics screen and derives its colors from the 256K palette Unfortunately this is the same resolution used by the four color Color Graphics Adapter CGA that IBM introduced eight years ago and the result is the same poor resolution that
76. 89 replace the handset in its cradle Fur thermore the circuit automatically deactivates when you pick up the same handset or one on another instrument If you were to connect a resistor with a value in the range of 1 000 to 2 000 ohms across your telephone line while the instrument is in use re placement of the handset in its cradle would maintain the talk listen path active However the hookswitch lo cated in the cradle will have discon nected the handset from the circuit so that whoever is at the other end of the line will be effectively excluded from any communication with you Shown in Fig 1 is the schematic diagram of the hold feature s very simple circuit With the circuit con nected to the telephone line as indi cated resistor R7 provides the actual hold function This resistor is ordi Say You Saw It In Modern Electronics narily kept isolated from the tele phone line by silicon controlled recti fier SCRI One of the operating principles of an SCR is that it is connected in series with its load in this case R and appears to be an open circuit through its anode cathode A K circuit until its gate G sees a positive going pulse voltage Once gated on the SCR continues to conduct current through its anode cathode circuit until that circuit is interrupted or its current falls below the threshold where conduction is possible At this point the SCR goes back to being an open circuit an
77. 89 for only 3 95 postage paid Date Numberof Copies Name Address City 1 State Zip Check MasterCard VISA Card No Expires Signature Signature required on all charge orders __ Mail to CO Communications Inc 76 North Broadway Hicksville NY 11801 May 1989 MODERN ELECTRONICS 85 S Classified Commercial Rates 1 per word 15 word minimum 15 00 prepaid Word PICKS UP A WHISPER 50 FEET AWAY count includes name and address ZIP code and abbreviation each count as one word piers NOTILU GS COR UTR eaea a P O Box number and telephone number count as two words each Indicate free cate less microphone Simply snap the unit on topofa 9V gory heading Computers Communications Electronics Video or Miscellaneous A battery and you can hear every sound in an entire house up to 1 mile away Use with any FM radio Tunes to any special heading is available for a 6 surcharge First word only is set boldface caps at no frequency from 70mhz 130mhz Easy to assembie kit T i ciudes aii peris and Vat ructi te Oh ds ob lax Rell charge Add 20 for additional boldf ace 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 The WIRELESS TELEPHONE TRANSMITTER model number Copy 1S subject
78. 9 9 9 c 9 c3 9 Heathkit Portable Air Cleaner Helps solve tough air Cleaning problems removes dust smoke other pollutants from 6 000 cubic feet 25 x30 x 8 room One evening kit includes power supply 3 speed fan control and assembled filter 120 VAC 60 Hz Dimensions 26 H x 174 W x 13 D Kit GDS 1297 59 Ibs 199 00 Accessory Replacement Charcoal Filter Assd GDA 1297 2 2 Ibs 9 95 components in Charging system tester Diagnose faulty your car s charging system with accuracy and ease two wire Setup and three quick tests show you if the battery has sufficient charge to reliably start the engine if the battery is being charged by the alternator if the voltage regulator is faulty causing the battery to become overcharged or if the alternator stator windings and rectifier diodes are functioning properly No external power or battery required Dimensions are 5 Hx 234 W x 4D Kit Cl 2065 2 Ibs 19 95 Noise generator kit To properly check out any stereo or sound X system with a spectrum analyzer you need a noise source with a nearly constant energy output This one evening Pink White Noise Generator will do just that and at a fraction of the cost of comparable noise generators Kit AD 1309 2 Ibs 24 95 For the electronic hobbyist Pocket size digital meter for home and shop Compact digital meter includes 3 digit LCD dis
79. 987 pp 121 through 126 So how do you plan to use thermistors To get you started a list of some of the many thermistor manufacturers appears elsewherein this column Theseand other manufacturers make many different types of thermistors that cover many dif ferent temperature ranges Some com panies also publish brochures and manuals about thermistors WE Thermistor Manufacturers Dale Electronics Inc P O Box 26718 El Paso TX 79926 Fenwal Electronics 450 Fortune Blvd Milford MA 01757 Keystone Carbon 1935 State St St Marys PA 15857 Omega Engineering Box 4047 Stamford CT 06907 Sensor Scientific Inc 1275 Bloomfield Ave Fairfield NJ 07006 Thermometrics Inc 808 U S Hwy 1 Edison NJ 08817 Yellow Springs Instrument Co Box 279 Yellow Springs OH 45387 SS E M May 1989 MODERN ELECTRONICS 77 Say You Saw It In Modern Electronics Ei PC CAPERS BEEN A Potpourri of MIDI Computer Hardware and Software By Ted Needleman For those of you just joining us the last two columns have concentrated on elec tronic music how it s developed and how your computer can make it more fun This month we ll finish off with a potpourri of assorted computer music hardware and software Oberheim Matrix 1000 Back in our discussion of MIDI instru ments I mentioned that a MIDI sound source does not necessarily have to be a keyboard synthesizer Arriving here too late for meto cover last month
80. As you can see when the output at pin 1 of JC 3 goes high the output at pin 3 of JC A also goes high This clocks JC 4A changing the states of its Q and not Q outputs at pins 1 and 2 The outputs of JC 6B and IC16C Say You Saw It In Modern Electronics ae eee a MAL e CE CN E MC c UO L UE Mc Nee occr ma ES np ENG OVEM OXEORLULTSOBLGULACCGUAHLLLELRHIDBGDGRLOEtL LICcLTTTECULEELICLLITCE L LTEHEZCICELLITETEZZZZEZLEITITTILTIIIETZZCTELECECEDLELOLESSIIZSI each drive one of the groups of five LEDs Therefore one pendulum LED at a time is on for about 0 1 sec ond for each count of C 13 Pendu lum swing direction changes when output pin 11 of 7C13 goes low and output pin 3 goes high because these two outputs are connected to the same C15A gate Since the counter wraps around each pendulum LED is on for two counts giving a more pendulum like action Output pin 9 of C13 is used to re set C14B via its pin 10 RESET input to ensure that C 4B is in proper phase with the rest of the clock set ting circuits Output pin 11 of JCJ6D has a 1 second repetition rate square wave on it and is used for timing functions in the rest of the clock The seconds and minutes counters shown in Fig 1 B are divide by 60 units These circuits are virtually identical to each other The only dif ference between the two is in the set functions The seconds counter is re set to O and minutes counter is ad vanced at the set
81. C WE WILL NOT BE UNDERSOLD UPS Shipping US 5 1245 Rosewood Deerfield IL 60015 10 Max IL Res 7 Tax 800 292 7711 312 541 0710 CIRCLE NO 123 ON FREE INFORMATION CARD Order Back Issues of l MODERN 2 Year Warranty WRITE FOR FREE CATALOG ELECTRONICS THE MAGAZINE FOR EL MAGAZINE FOR ELECTRONICS amp COMPUTER TER ENTHUSIASTS BACK ISSUE ORDER FORM Please send me the following issues of Modern Electronics 2 50 each Month s amp Year s Total Payment Enclosed Check or M O only NAME May 1989 MODERN ELECTRONICS 67 Computers Apple s High Performance Macintosh SE 30 Desktop computer operates at up to four times as fast as the Mac SE and provides MS DOS and OS 2 disk compatibility lose on the heels of the com pany s announcement of the Macintosh IIx see New Products February 1989 Apple an nounced the Macintosh SE 30 an other computer built around the Mo torola 68030 32 bit microprocessor and 68882 floating point math co processor Both are desktop units but the Mac SE 30 is Apple s first transportable computer to capitalize on such state of the art technology With the packaging of the Mac SE 30 Apple has taken a step backward with the return to the small footprint enclosure used by the original Macin tosh computers a welcome move for people who have to lug the machine around and have limited desktop space for their computers
82. ICD 08559 MAY 1989 2 50 CANADA 3 50 THE MAGAZINE FOR ELECTRONICS amp COMPI MAGAZINE FOR ELECTRONICS amp COMPUTER ENTHUSIASTS E Cumulative UV Alarm For Safe Suntanning ll How To Use Frequency Counters SunGuard Alerter For Safe Sunbathing p 22 Plus Apple s new Macintosh SE 30 68030 Based Computer e Forrest Mims Experiments with Thermistors e MIDI Computer Hardware amp Software e Evaluating Conversion Unit Software e Electronics amp Computer News e Latest Technical Books amp Literature more Tm S Por mai aM F Piel Lc eee iE l y i re oe A CINIMTER COUNTE P fa Das CT e Dagogobo ce TOUuD TAME 460 1000 man EEI bi EA i Cet COUNTER THEORY Affordable compact and ultra sensitive More and more people are discovering new applications for our counters than ever before Now used by technicians engineers law enforcement officers private investigators two way radio operators scanner hobbyists and amateur radio operators just to name a few Over 15 years of service quality experience and dedication has proven you can count on us Hand Held Series Frequency Counters and Instruments MODEL 2210 1300H A 2400H CCA CCB RANGE FROM 10 Hz 1 MHz 10 MHz 10 MHz 10 MHz TO 2 2 GHz 1 3 GHz 2 4 GHz 550 MHz 1 8 GHz APPLICATIONS GENERAL PURPOSE RF MICROWAVE SECURITY SECURITY AUDIO MICROWAVE PRICE 199 169 249 299 99 SENSITIVITY 1 KHz 5mv NA NA NA NA 100 MHz lt 3mv
83. II codes for the letters specified by the ASC operator in BASIC Characters are written to M7 at hex address C200 The 2 in C200 sets A9 high to program M1 to re ceive the character codes The mod ule increments its address counter af ter each character is displayed so the eight character message fills the first eight positions on the module Although the 16 character posi tions of M1 are physically arranged in a single line they are addressed in two logical lines Positions 1 through 8 are at hex 80 through 87 while posi tions 9 through 16 are at CO through C7 The jump in addresses between the two lines has to be taken into ac count when programming the module This is why line 140 sets MI s address counter to CO to specify position 9 Lines 150 through 220 write WATCH to positions 9 through 16 to finish the message Program 8 tests the operation of switches S2 and S3 by continuous ly monitoring Port 1 and giving a message on the terminal screen when a switch is pressed Type in and run this program Then press 2 and S3 and watch for the appropriate messages The switches connect to otherwise unused lines on Port 1 an eight bit I O port of JC2 Line 30 reads the value of Port 1 and line 40 finds the sum of bit 0 and bit 1 If the sum equals 2 bit 0 is low which means S2 has been pressed If the sum equals 1 May 1989 MODERN ELECTRONICS 43 Program 9 Combine Features of Programs 6 amp 7
84. IN MINUTE 766 RETURN 776 REM eeeeettteerundate time subroutine ttteeektetneneteee International Inc 780 TIME TIME 60 MINUTE MINUTE 1 CALL TOLL FREE 7908 IF MINUTE 68 THEN HOUR HOUR 1 MINUTEs 880 IF HOUR 25 THEN HOUR 1 1 800 338 0531 B18 RETI 340 E First St Dayton OH 45402 Local 1 513 222 0173 CIRCLE NO 139 ON FREE INFORMATION CARD Say You Saw It In Modern Electronics May 1989 MODERN ELECTRONICS 45 Project Put Your Telephone On Hold Low cost add on circuit gives any telephone instrument a hold feature By Andrew Van Loenen ne of the nice features you will find on many modern telephone instruments is a hold button The ability to put your line on hold allows you to hang up the phonein one room and pick up an instrument in a different room without disconnecting the person at the other end of the line or having to run back to hang up the original in strument It also allows you to con verse privately with someone in the same room without having to hold your hand over the mouthpiece of the handset or juggle with the tiny mute button found on some phones Hence the hold feature also doubles as a mute function In this article we describe a sim ple low cost circuit that you can build and install in just about any telephone instrument to give the lat ter a true hold feature The circuit is so simple containing just five very small components and a st
85. ISTORS Me fe Me 39 100 3k 1 0D te ie 1 0D em erstes on 3 20 Voc X ra 7 g 1 7A du P C board tour Cate POZOS 175 cach 10 fes 82 OO 100 tr 81 OD FLASHING LED XENON TUBE 1 tang Anette wh 3 177 d ard viec wate teni lur anann ias er rety momon Cate Fit 2 ks to NICKEL CAD BATTERIES RECHARGEABLE PC XT EPROM ASK ABOUT SE RISESEISIICOSPPPELE PROGRAMMER id Nis SPECIALI es a 169 PROGRAMMER irt WIDE BAND AMPLIFIER NECS UPT ISSIQ 1200 wru OI 10 ter 1140 100 ke 0126 00 CATs UPC 1665 2 tw 91m Ot MSO 100 er 68 CC N CHANNEL MOSFET BE 419 TO 22C cue LATEST DESIGN PROGRAMS UP TO 4 DEVICES AT ONE TIME FEATURES EASY TO USE MENU DRIVEN SOFTWARE THAT RUNS UNDER PC OR MS DOS USES AN INTELLIGENT PROGRAMMING ALGORITHM FOR SUPER FAST 8X EPROM BURNING THIS PLUG IN BOARD ATTACHES TO AN EXTERNAL MINI CHASSIS CONTAINING 4 TEXTOOL Z 1 F SOCKETS NO PERSONALITY MODULES REQUIRED AUTOMATIC VPP SELECTION 12 5V 21V OR 25V EPROM DATA CAN ALSO BE LOADED FROM OR SAVED TO A DISKETTE PROGRAMMING SOFTWARE SUPPORTS 2716 2732 2732A 2764 2764A 27128 27128A 27256 27256A 27512 AND 27512A ASSEMBLED AND TESTED BURNED IN WITH MANUAL 169 WITH SOFTWARE JUST RECEIVED SAME AS ABOVE PROGRAMMER BUT PROGRAMS 8 UNITS AT ONE TIME 299 Digital Research Computers P O BOX 381450 e DUNCANVILLE TX 75138 e 214
86. NTROLLED Works with 3 digit 125 4v digit 175 Convenient one hand operation SL1 30 135 Digital display Temp range 300F 900F Grounded tip Overheat oro with Dattenes Measures DCV ACV Ohms Audible continuity check Deta hold ply XP 580 Fully regulaled and short CieCuil protected 59 95 2 20V at 2A 12V al 1A SV at 3A 5V at 5A XP 575 without meters 39 95 GF 8016 Function Generator with Freq Counter 239 Sine Square Triangle Pulse Ramp 2 to 2MHz Freq Counter 1 10MHz GF 8015 without Freq Meter 179 9 Ranges tpt 20 000uld 5 basic accy Zero Control with case All Nave color coded posts Provides sing tri squ wave From tH to MHz AM or FM capability S5 10M HZ Molherboard B Expansion Siots Math Compressor Siots 360K Floppy Drive AT Style Keyboard Measures Coils 1uH 200H Caps 1p 200ut fes 01 20M 3 2 digit LCD 1 DC Accy 10A Scale amp Gee AUTO Zero 7 Ipotarity Decade Blox mm 9610 of 9610 Resistor Bion 4 ohm to 1M amp 100K pot 9620 Capacitor Blox 47pi to 10MFD MODEL PC 1000 150W Power Supply 256K RAM Enpandabie to 640K Monochrome Monitor Monographic Video Card ePareliei Printer Port FREE spreadsheet and word processor 3 3MS DOS and GW Basic add 75 15 Day Money Back Guarantee Number ordered 2 50 each STREET ADDRESS CIT NER Te SS M lE e DOO DARE DDEDS LVEL DEG am C amp SSALES IN
87. ODERN ELECTRONICS May 1989 see an increase in the horizontal scan rate to improve the sharpness of dis played images No one knows for sure when the VESA standard will be finalized or approved if at all If it is adopted VESA will represent the first indus try wide acceptance of a video mode that was not developed by IBM since the Hercules Graphics Card ap peared on the scene VGA Monitors The secret to VGA s multi colored success lies with the VGA video mon itor Unlike CGA and EGA which use a digital display monitor VGA uses an analog monitor Digital display monitors also called TTL monitors display colors by feeding binary values to the color guns of the CRT Each gun has its own separate input that is assigned a position in a binary code To display red for example the green and blue Say You Saw It In Modern Electronics Manufacturers amp Suppliers of VGA Boards Amdek VGA Adapter 132 445 Amdek Corp 3471 N First St San Jose CA 95134 408 922 5700 AST VGA Plus 599 AST Research 2121 Alton Ave Irvine CA 92714 714 863 1333 Compaq Video Graphics Controller 599 Compaq Computers Inc 20555 FM 149 Houston TX 77070 713 370 0670 Everex EVGA 399 Everex Systems Inc 48431 Milmont Dr Fremont CA 94538 415 498 1111 Genoa Super VGA 429 Genoa Systems Corp 75 E Trimble Rd San Jose CA 95131 408 432 9090 guns would be turned off and only the red gun would be
88. OF THE 1990 S IF you are able to work with common small hand tools and are familiar with basic electronics i e ableto use voltmeter understand DC electronics IF you possess average mechanical ability and have a VCR on which to practice and learn then we can teach YOU VCR maintenance and repair FACT up to 90 of ALL VCR malfunctions are due to simple MECHANICAL or ELECTRO MECHANICAL breakdowns FACT over 77 million VCRs in use today nationwide Average VCR needs service or repair every 12 to 18 months Viejo s 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 3540 lishire BL STE 310 Los Angeles CA 90010 Dept ME CIRCLE NO 103 ON FREE INFORMATION CARD While watching rental movies you will notice an noying periodic color darkening color shift un wanted lines flashing or jagged edges This is caused by the copy protec tion jamming signals em bedded in the video tape such as Macrovision copy protection DIGITAL VIDEO STABILIZER RX complete ly eliminates all copy protec tions and jamming sig
89. Operating at up to four times the speed of the original Macintosh SE the Mac SE 30 also provides MS DOS and OS 2 disk compatibility Thus it provides a bridge between the two major personal computer de signs and philosophies in the current arena Three configurations of the Mac intosh SE 30 are available At the en try level the machine comes with 1 megabyte of RAM and a single 1 4 megabyte floppy disk drive and re tails for 4 369 Option number two offers the same machine with an in ternal 40 megabyte internal hard disk at a retail price of 4 869 At the top end of the line the SE 30 comes equipped with 4 megabytes of RAM and an 80 megabyte internal hard disk at 6 569 Users of theoriginal Macintosh SE who wish to obtain full Macintosh SE 30 functionality from their com puters can do so with an upgrade kit from Apple No price was available for the upgrade kit at press time Mac SE 30 Features The Macintosh SE 30 is a two unit system One unit contains the system circuitry and integral high resolution video display monitor the other is the detached keyboard Operating the 32 bit 68030 micro 68 MODERN ELECTRONICS May 1989 processor at 16 MHz and taking ad vantage of the chip s on board 256 byte data and instruction caches give the Mac SE 30 its up to four times speed edge over the original Mac SE Additionally the companion 68882 coprocessor is claimed to boost the new computer s performance i
90. RONICS 79 Say You Saw It In Modern Electronics PC CAPERS in songs you input using one of the other song composing techniques provided in the software Another interesting feature of the C MS is the ability to display text and graphics on the PC s screen synchro nized with the music This can be used to produce animated song presentations and sing along songs that display lyrics as the song progresses These graphics however must be created with another program such as one of the many avail able paint or draw packages not supplied by Creative Labs Making music is a bit more difficult than playing it The intelligent organ feature is clever and works pretty well considering that a PC s keyboard is a lot more complex crowded and cluttered than a real organ type keyboard The first 7 leftmost keys in each of the 4 rows of keys are mapped to the 7 white keys on the organ keyboard covering 4 octaves You can shift the actual coverage of these 4 octaves up and down a virtual key board by using the cursor left and right arrows on the numeric pad Playing flats and sharps the black keys is difficult though You have to either hold down a shift key while playing the large key board or use the tab key to shift to a smaller two octave keyboard that lets you directly play the flats and sharps The intelligent organ allows you to save and recall songs and add automatic chord bass and
91. S OF ABOVE PLUS HUNDREDS MORE AVAILABLE FOR 1 00 OR INCLUDED FREE WITH ALL ABOVE ORDERS PLEASE INCLUDE 3 00 PH ON ALL KITS AND PRODUCTS PLANS ARE POSTAGE PAID SEND CHECK MO VISA MC IN US FUNDS INFORMATION UNLIMITED P 0 BOX 716 DEPT ME AMHERST NH 03031 CIRCLE NO 150 ON FREE INFORMATION CARD May 1989 MODERN ELECTRONICS 49 Project A Smart Car Relay Provides automatic operation sensing and switching for equipment used in an automotive electrical environment By Dennis Eichenberg T here s a need in the automo tive electrical environment for a circuit that develops a control signal when it senses that any electrical device is operating For ex ample you might connect an under dash tape player to existing in dash speakers In this application the speakers are normally connected to the in dash unit but the Smart Car Relay automatically switches them to the under dash unit when the latter is turned on In another appli cation a power antenna can be made to extend or retract whenever the ve hicle s radio is turned on or off The Smart Car relay described here is just the ticket to provide auto matic switching for such applica tions This compact inexpensive and easy to build and install project re quires no modifications to be made to the equipment whose operation it is used to sense and control Further more it provides protection against reverse polar
92. TORS Ll nd wm 1 4 Won Deaar fae ony tie derd r IM Wert Mele F m Resto ener enertes TRANSFORMERS Dual Secerndary Bangin Promery CO 44 E P I Wen Troneber mers H Sipe k uus Datoer SSe J a 4 4 BNS5En i vuxua S pu inis uERSESSSEgS 33 amp aSG Bt amp EttAttt ES J 3 h TS E A00BEN LI 478 a 0 guns M ao OC N Boy acy 2A Mts L WITEN 75 7D TEs x 483AN i944 CN wen nse m 1 J gt a N D MIPA 23 a7 395 agi Tet N 121 ac 45472 4 80 atinin n atn sa MSAPN 4 apisecw 325 go 434 4 Lanes ts MIDS EN 00 engin ET at d regi eL N se 9s P N i Mf Pan g os b 4 aCOSA CN 2 Re EN ASIN Ck D aaach ad t7 mene 41548 e 50 amp 28 amp CN mM DET vM 415A amp 0708 CN m Jeran amp SDR hg 90 4197 74C00 408 ai ANTE CS 10 JaMiAN F CMOS 4149 CN an 45 MAN MON M 40354 CN 460m Come 40404 C8 AT eM a MMT S dL el m 404274 1 73N as 00 N pal Dany 4 JSI FSA 3 4 Wy t 4 81N s LL ia et Fapta MMEAN MIIN tN ELECE FE 8 LRPIPIPIT RESRESE A aD a S 23 P P4154 2700 gi 50 ax Donia vaH i1 33D y gt ax T th Poise 470 c o 3 a far L D D 74 sr f n sisa QUUD LU LE UI za 000 C 0 o P 7000 s e 400
93. You get everything you need the skills the confidence and the equipment to feel completely at home with today s robotics technology v 94 EN a wA ee Step by step you get the training you need to move into robotics fast You need no previous experience to succeed with NRI training because NRI takes you from elec tronics basics all the way up to the state of the art in robotics technology You train from the ground up first gaining a working knowledge of electronic circuits and components as you experiment with your NRI Dis covery Lab and professional digital multimeter Rapidly theory becomes under standing as you move on to digital logic computer fundamentals right up to writing practical programs to control specific robotic operations using NRI s Robotic Programming Language software included in your course Your success is assured by your personal NRI instructor whose expertise and personal guidance are always available to you whenever you need a helping hand along the way Get training you can build a career on send for your FREE catalog today TV video audio servicing electronic music technology security elec tronics and other growing high tech career fields If the coupon is missing write to NRI School of Electronics McGraw Hill Continuing Education Center 4401 Connecticut Ave Washington DC 20008 See for yourself h
94. _9 300MH AMPLIFIED active 708 14DB gain For Shortwave AM dd P O BOX ecanner TV FM Receive only APARTMENT ANTENNA Suction cup mount VAK TENNA mounts on glass MARINE a MEDFORD NY 11763 616 764 9798 110VAC of 12VDC powered SEND FOR FULL DETAILS ADD 4 S H amp Tax if NY CIRCLE NO 110 ON FREE INFORMATION CARD Free Product Information Readers can obtain free information on products advertised by the above compa nies as well as for some editorially men tioned products Simply circle the appro priate number printed below an adver tisement onto the Modern Electronics Free Information Service card bound into this issue After filling in your name and address just mail the postpaid card Your request will be forwarded directly to the advertiser with a mailing label pre pared by our reader service department to ensure speedy response SOLAR ELECTRIC SYSTEMS Discount prices SUN POWER TEXAS P O Box 2788A ME Freeport TX 77541 409 233 8350 AT LAST An educational and practical cir cuit Mutes stereo TV when phone rings or is in use Schematic 5 00 with power supply Phone jacks 14 00 COYOTE CONTRAP TIONS 1906 S Espina Suite 30 Las Cruces NM 88001 COMPUTERS COMMODORE REPAIRS low cost CHIPS PARTS DIAGNOSTICS Heavy duty POWER SUPPLY for C64 27 95 plus UPS Kasara Microsystems division of QEP 1 800 248 2983 APPLE and IBM comp
95. a Ohio 43062 VIDEOCIPHER II VIDEOCIPHER II Manuals Volume 1 hardware Volume 2 software Either 32 45 Both 54 95 Volume 3 Projects software 42 50 Volume 4 Repair 97 45 CODs 1 602 782 2316 Catalog 3 00 TELECODE Box 6426 ME Yuma AZ 85366 6426 INVENTORS INVENTORS Can you profit from your idea Call AMERICAN INVENTORS COR PORATION for free information Over a de cade of service 1 800 338 5656 In Canada call 413 568 3753 i RECORDING INSTRUCTION BE A RECORDING ENGINEER Train at home for High Paying Exciting Careers FREE Information AUDIO INSTITUTE BIOMEDICAL Electronics get started in this high tech field detailed book 3 50 Tech Search P O Box 2855 Atlantic GA 30301 PRIVACY PROTECTION SURVEILLANCE and counter surveillance equipment catalog Send 7 00 RWB Elect ronics P O Box 922 Bronxville NY 10708 914 779 0607 VIDEO DIGITIZER INEXPENSIVE IBM PC or C64 VIDEO DIGITIZER Digitize RS170 TV video VCR or camera Capture images to disk IBM PC or XT 4 77 MHz requires CGA 59 95 Commodore 64 128 39 95 Disk software documentation pretinned and drilled PCB Easily assembled Uses common low cost parts Specify computer SASE for informa tion KINNEY SOFTWARE DEPT ME 974 Hodsdon Road Pownal Maine 04069 MISCELLANEOUS ASIAN LADIES want correspondence for friendship marriage SUNSHINE INTER NATIONAL Dept TW Box 5500 Kailua Kona HI 96745
96. a hazy sky Thus SunGuard automatically takes into account variations in sun intensity and totals the cumulative amount of exposure You manually set the desired 22 MODERN ELECTRONICS May 1989 amount of time of exposure to the sun before you begin a sunbathing session An adjustment range of less than 10 minutes to almost 2 hours is possible with the circuit as shown in the Fig 1 schematic diagram Power to operate the circuit is pro vided by a common 9 volt transistor radio battery Current drain of the circuit is very low so one alkaline battery should easily last through the entire summer season Also a handy pushbutton switch allows you to quickly check battery condition to determine if there is sufficient energy to operate the circuit Referring to the complete sche matic diagram shown in Fig 1 the heart of SunGuard is photocell PC7 which is the reference that continu ously monitors the intensity of the sun s energy and generates a current that is directly proportional to the de Say You Saw It In Modern Electronics Fig 1 Complete schematic diagram of SunGuard s circuitry tected intensity at every given mo ment On a day of unobstructed bright sunlight when the sun is direct ly overhead the sun s energy intensi ty is at its maximum and is referred to as l full sun As the sun traces its path across the sky from east to west this intensity will vary increasing in the morning and becoming
97. aire indicating they have a Post Grad uate degree Ph D MD etc as com pared to 1986 s 11 6 Another 12 4 have done some Post Graduate study vs 86 s 11 The next highest educational level cate gory Graduated College or a Technical Institute accounted for 45 6 of re spondents to our questionnaire com pared to 1986 s 25 3 This is likely somewhat distorted since the 1986 survey did not include Technical Institute many of which are two year institutions among the choices However examining the next lower level Attended or Attend ing College reveals that the current sur vey drew an 18 6 response for this choice while an expansive 35 5 noted this in 1986 Part of the difference I d guess is that some tech institute gradu ates did not check off College in 86 but instead marked the lower Attended At tending College level choice The major difference however is that more about 990 trained electronic technicians are reading Modern Electronics now than three years ago Adding both together Graduated At tended Attending 1989 s total is 64 2 while 1986 s was 60 8 Not much of a difference really given a sampling error of a few points in either direction It does however give us a better picture of how many of you completed their formal post secondary school training since there was a shift of 20 3 to College Institute and a loss of 16 9 in At tended Attending college It changed
98. alize that 1 have a way to go before can I consider myself a PageMaker expert Ted Needleman Author s Update It was a pleasure to see how nicely my article on Calculator Music in the March 1989 issue was presented I did no tice two small errors that would prevent the program from running properly One is the the slash after the first SWAP com mand which should actually be a power sign Alert readers may be able to figure out the problem from the text but I thought you would like to print a correc tion The other is that the last number in the Z routine should be 2 not the that was printed David A Nordquest May 1989 MODERN ELECTRONICS 83 The SunGuard from page 27 Perform the calibration procedure as close as possible to June 21 the summer solstice in the northern hemisphere when the sun s energy is at maximum intensity to obtain maximum accuracy Otherwise any clear sunny day in June or July will be fine for calibration purposes However wait until the sun is over head about noontime when adjust ing trimmer control R4 Set the meter to a 10 or 20 volt dc full scale range Connect its common probe to the negative lead of C2 Clip the positive probe to pin 14 of JC Place the project so that the sunlight falls directly on the solar cell with the plane of the cell held as close as possible to perpendicular with the sun do not look into the sun itself
99. an under dash mono tape player when the latter is turned on The simple relay contact arrange ment shown in Fig 1 is adequate for this The hot line from the speaker would connect to the COMMON relay contact the output line from the ra dio to the NORMALLY CLOSED con tact and the output line from the tape player to the NORMALLY OPEN contact Under normal conditions with the radio off or on and the tape player off the speaker would be connected to the radio s output Now if you wish to listen to a tape you simply turn on the tape player This causes current to be routed through RECTI Theresulting 1 4 volt drop across the rectifier assembly is then coupled through R to the base of Q7 When this occurs Q7 conducts and ener gizes K1 Now the relay s armature is pulled down closing the NORMALLY OPEN contact and opening the NOR MALLY CLOSED contact In so doing the circuit is completed between the output of the tape player and speaker If you had planned on using the project to switch speakers in a stereo system you would have needed a re lay that has dpdt contacts for K7 The project is versatile enough to control even more lines than this de pending on the relay contact arrange ments or even number of relays used More about this later In this event a separate set of contacts would be us ed to switch the speaker between the outputs of the radio and tape player in each channel To return to normal c
100. and opto isolators lin ear and digital IC s thermal cutoffs and a variety of special purpose devices such as silicon unijunction transistors UJT s programmabie unijunction tran sistors PUT s and bidirectional diode thryistors SY DAC s All Philips ECG components are tested and guaranteed to equal or exceed OEM specs so you can be sure If it s ECG it fits and it works And with Philips ECG universal replacements you can handie Jobs with less inventory and lower inven tory costs The entire Philips ECG line is detailed in the ECG Semiconductors Master Replacement Guide Stop In or call us today for your copy of this val uable guide EE d ETE Yr Fz hss Aa d GP nus iile NS SRUWPEWEWwWP Glenview Industrial Center 4316 4318 Regency Drive Glenview IL 60025 312 298 0800 FAX 312 298 0805 CIRCLE NO 104 ON FREE INFORMATION CARD Be anFCC LICENSED ELECTRONIC TECHNICIAN Br NA y Sn Learn at home in spare time r uh S No previous experience needed Eamupte 7 1 1 t3 4 30 an hour l 6 and more No costly School No commuting to class The Original Home Study course pre pares you for the FCC Commercial Radio telephone License This valuable license is your ticket to thousands of exciting jobsin Communications Radio TV Micro wave Computers Radar Avionics and more You don t need a college degree to qualify but you do need an FCC License
101. and without damaging it re quires the operator to know some thing about the signal it will receive This shouldn t be surprising the same is true when working with a multimeter where you should know if the signal is ac or dc and what is the anticipated voltage range to be set And as with any test instrument dif ferent models often have different features and operating nuances It s important therefore to study the manufacturer s operating manual and familiarize yourself with the counter s switches and controls You should never exceed any in strument s input limitation of course In the case of a frequency counter neophytes may overlook such a precaution for one reason or another For example one might have an inordinate desire to check out his electric utility company s ability to maintain ac current at pre cisely 60 Hertz by connecting a count er sinput probe directly to a 117 volt ac outlet Do not do this naturally unless you want to see your count er go upin a puff of smoke and possi bly suffer an electric shock yourself Use caution too when measuring a transmitter s antenna output Do not directly connect the counter s in put to the transmitter s output be cause the instrument s input circuitry will likely be damaged when the transmitter is keyed Other safe ways to check a transmitter s output will be explored later To give you a clearer idea about the seriousness of keeping in mind the strengt
102. andard size switch that it can easily mount inside virtually any telephone instru ment no matter how compact it might be Installation in no way in terferes with normal operation of your telephone instrument About the Circuit Most single line home telephone in struments operate from a single pair of wires The exception are instru ments that have a light in the dial but even then the talk listen path is a single pair of wires that come from your local telephone company By tradition the wires are identified by the telephone company as tip green insulation and ring red in sulation These identifiers date back to when operators used to patch tele phone lines from origin to destina tion with patch cords that had plugs with tip and ring contacts on them Also by tradition telephone voltages are negative with respect to ground common Green insulated wire is the com mon ground line and the red in sulated wire carries 48 volts when your telephone instrument is on hook and about 6 volts when the handset is lifted off the hook To answer a telephone it is neces sary to provide a relatively low resis tance dc current path across the tip and ring conductors As long as this path is maintained the telephone line is in the busy mode The ob ject of our hold circuit is to provide this path by pushing a button as you 46 MODERN ELECTRONICS May 19
103. antenna lead of any vhf marine transceiver and connects to the unit s 12 volt dc power supply Received signals are boosted by at least a speci fied 13 dB An internal relay automa tically bypasses the RFTR M preamp continued on page 69 16 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics SELECT 5 BOOKS 777 STATE for only 395 m values to 134 70 and get a FREE Gift 2975 24 95 THe CAMP ETE HANDIM BOR OF VIDEOCASSETTE f 1938 60 00 Counts as 3 REC ORDERS electroni s TRE MASTER E COOKBOOK 1199P 18 95 A p 2731P 14 95 20 D Electronics projects ideas the latest technology all at up to 50 off publishers prices B TT Membership Benefits Big Savings ir addition to this introductory STATE OF offer you keep seing substantially with members prices of up to 5096 off the S LID STATE publishers prices Bonus Books Starting immediately you will be eligible for O i mer nw our Bonus Book Pian with savings of up to 80 off publishers prices Club News Bulletins 14 times per year you will receive the Book Club News describ ing all the current selections mains alternates 3xtras pius bonus offers and special sales with scores of titles to choose from Automatic Order If you want the Main Selection do nothing and it will be sent to you automatically If you prefer another selection or no book at al
104. ar right K2 No 2 Fig 4 Automatic speaker switching between two audio units and four speakers This requires two auxiliary relays screws down only tight enough to slightly compress the rubber grom mets not so tight that the project is rigidly mounted Now disconnect the 12 volt lead from the device that is to be con trolled Clip the lug from the end of this wire and strip 4 inch of insula tion from the end of the wire Crimp and solder the same type of lug onto the free end of the 12V OUTPUT wire coming from the junction of R7 and RECTI on the circuit board as sembly and plug this onto the termi nal of the device being controlled from which the 12 volt wire was removed Crimp and solde one end of an au tomotive in line fuse holder obtain able from any auto supply outlet to the free end of the 12V INPUT wire coming from the junction of Q s collector and RECTT s negative ter minal Crimp and solder the free end of the 12 volt wire that was re Say You Saw It In Modern Electronics moved from the device to be con trolled to the other lug of the fuse holder Open the fuse holder and place a suitably rated fuse in it Complete the electrical system wiring by connecting the free end of the GROUND to any convenient chas sis ground point in your vehicle Ter minate the GROUND wire from the project in a ring lug Then fasten the ring lug to the vehicle s chassis with an existing screw or a sepa
105. area in which frequency counters are used whether it s for checking a ham radio transmitter s frequency or a comput er s clock frequency There are two basic ways to makea counter read frequencies One is the traditional way of directly coupling the counter s input connector through Say You Saw It In Modern Electronics May 1989 MODERN ELECTRONICS 33 acable ora probeto a device s output always observing the precautions previously cited Alternately a pick up antenna can be employed to re ceive the signal to be counted through the air Direct Connection Method As an example of the direct connec tion method you can verify frequen cies of various signal generators by directly connecting a cable between the generator s output and the count er s input This might sound easy enough and it is with an exception Using the right connectors for the job can be a frustrating chore at times Consequently plan on having an as sortment of adapters on hand The counter in this project uses a female BNC military designa tion UG1094U for its input connec tor whichis pretty much standard on many types of generators and other test equipment Type N is also commonly used so a Type N to BNC adapter would certainly be use ful to have I recommend too hav ing a 6 foot long coaxial cable with a male BNC on each end on hand for connection adapting purposes Many oscilloscopes also
106. atible computers from 399 monitors from 69 Printers disk drives paper diskettes and more Send SASE for complete list Mr G s Computers R R 5 Box 205A Portland Indiana 47371 SOFTWARE Schematic amp PC Board Fonts Electronic Programs amp Dictionary For c64 or c128 with Geos tm Send 19 95 or write Thomas Software 1375 Beasley Rd Jackson MS 39206 COMPUTER REPAIR DEPOT IBM Com paq Apple AT amp T and many others Call Bi Tronix Inc 408 236 3385 or 209 952 7116 PO Box 23069 San Jose CA 95153 SUPER XT COMPATIBLE MOTHER BOARD SI 7 7 DESIGNED TO DIRECT LY REPLACE XT OR COMPATIBLE MOTHERBOARD FOR SPEED UPGRADE CTI 1418 UPFIELD SUITE 127 CAR ROLLTON TX 75006 CO MMUNICATIONS COMMUNICATIONS PLANS BOOKS KITS AM FM broadcasting licensed unli censed 1750 Meter transceivers ham CB amplifiers surveillance bugs more FREE catalog PAN COM Box 130 MES Paradise CA 95967 SURVEILLANCE COUNTERSURVEIL LANCE Send 2 00 for catalog of state of the art equipment books Sherwood Box 535M Southampton PA 18966 telephone number 215 357 9065 ALUMINUM image transfer process your artwork to aluminum Write J amp E Enter prises 2457 N Marmora Chicago Illinois 60639 AUDIO DIGITAL stereos speakers amplifiers equalizers cassette recorders walkmans tele phones CBs antennas Catalog 1 Expo tronics Enterprises Dept M 1222 Highland
107. ature Alarms As you ve probably figured out by now NOTEBOOK thermistor voltage dividers and bridges can be easily connected to operational amplifiers and comparators to imple ment many interesting and useful appli cations Comparators are particularly easy to use with thermistors Shown in Fig 13 is a schematic dia gram for a simple low temperature alarm If you examine this circuit careful ly you ll see that the voltage divider made up of thermistor R and resistor R2 is actually half of a Wheatstone bridge The other half of the bridge is made up of potentiometer or adjustable voltage di vider R3 In this application R3 is con sidered to be the source of an adjustable reference voltage In operation R3 is set so that the com parator switches and the buzzer is activat ed when the temperature drops to a pre determined point For example the cir cuit can be set to sound the buzzer when the temperature is at or near freezing by adjusting R3 when the thermistor is im mersed in ice water The thermistor should be selected to re spond over the temperature range you wish to monitor In most applications the resistance of R2 should be approxi mately equal to the resistance of the ther mistor at room temperature The ther SEE TEXT FOR vALuES Fig 11 Circuit details of a Wheatstone bridge temperature sensor mistor I selected had a resistance of 2 000 ohms at room temperature Therefore used a 2 2
108. be s 10 megohm series im pedance will eat up most of the sig nal This would leave too low a signal value to trigger the counter Only 1 x probes or direct cables can work on the very high frequency range B due to its very low input impedance Low frequency measurements are made easier by using a low pass filter probe It reduces false counting from higher frequency components A schematic for such a two stage filter is illustrated in Fig 2 along with its response curve Component values are not critical and the device is easy to build The probe can only be used Say You Saw It In Modern Electronics for low frequency counting as in the project s A range There will be times when you may want to take your count inside a cir cuit Perhaps this is in the oscillator circuit Don t be surprised to discov er that you can t get a satisfactory reading in such instances The signal level will likely be too low Ycu ll ei ther require a preamplifier or probe with a built in wideband amplifier to boost the gain or use high priced counter with a built in wideband am plifier to obtain a usable signal Measuring crystal oscillators can be a problem because a probe might load the circuit causing the frequen cy to shift or worse cause the oscil lator to cease oscillatinz Many oscil lator circuits provide a calibration test point to avoid this The best way to proceed in a crystal oscillator is to u
109. ce Fig ure 8 shows a sample display on M1 Data and instructions are written PARTS LIST Semiconductors IC12 ADCO804 analog to digital converter IC13 LM7134 precision Fahrenheit tem erature sensor Digi Key IC14 LM385 1 2 voltage reference diode Digi Key IC15 74L500 quad NAND gate Capacitors 25 W V C19 C21 1 0 eF tantalum electrolytic C20 300 pF ceramic Resistors watt 5 tolerance R17 10 000 ohms R18 75 ohms R19 100 000 ohms R20 5 000 ohm pc mount potentio meter Miscellaneous MI LTNIIIR 10 16 character LCD module Digi Key Cat No AMX116 ND S2 S3 Spst normally open momen tary action pushbutton switch Three conductor shielded cable 60 inches long 34 conductor ribbon cable with connectors at both ends 8 inch long see text 14 pin single row header 34 pin double row head er Wire Wrap IC sockets and hard ware rubber grommet small diame ter heat shrinkable tubing machine hardware hookup wire solder ctc Note For a 2764 EPROM containing the 10 programs listed in this article plus tem perature alarm program send 19 to Lakeview Microdesigns 2209 Winnebago St Madison WI 3704 Include 2 PAH per order Wisconsin residents please add 5 state sales tax Supplier Addresses Digi Key Corp 701 Brooks Ave S Thief River Falls MN 56701 0677 1 800 344 4539 Jameco Electronics 1355 Shoreway Rd Belmont CA 94002 415 592 8097 Sources of I
110. chases of Tektronix products This full color quarterly publication con tains complete descriptions of a sampling of the company s products Among the items featured in this latest edition are portable oscilloscopes a logic analyzer accessories software and training aids through 8 deal with in circuit testing of high frequency transistors transmitter receiver servicing TV servicing and an tenna systems and transmission lines Practical testing measuring and digital instrument building are covered in Sec tion 9 Here the reader is given schematic diagrams for building a logic memory probe logic pulser LED indicators and a multi channel logic analyzer Finally Section 10 gives time saving tests and measurements for semiconductors Each test or measurement procedure is approached in a logical time saving manner It begins with arun down on the test equipment needed and then briefly describes the required test setup Follow ing this comes comments which general ly deal with the symptoms of the problem for which the test is being conducted Thereafter a by the numbers procedure is given for conducting the test or mea surement Wherever needed schematics drawings tables and whatever else is needed to clarify the procedure are given If you do a lot of servicing this book can quickly pay for itself by making you a faster more efficient troubleshooter It is well worth its modest cost Fora copy of the Tek Dir
111. circuit ground The COUNT OUTPUT at pin 12 of C12 goes to the CLOCK inputs at pin 11 of C1B and pin 14 of C13 The signal that ap pears at the not Q output at pin 12 of IC14B directly connects to the DATA input at pin 9 to form a divide by two counter Hence the FAST SET output from C14B at pin 12 is a 5 Hz 60 Hz 12 square wave pulse train that is used to quickly set the clock Decade counter C 3 is permitted to run in normal count mode with its 10 outputs counting up and down Its COUNT OUTPUT at pin 12 is in verted by JC D to drive the CLOCK input at pin 3 of JC 4A The Q and not Q outputs at pins 1 and 2 of IC14A are inverted and buffered by NOR gates C16C and CI 6B re m MM H M d c E 01 8666 Fig 2 Actual size etching and drilling guides for the top upper and bottom lower of the pendulum printed circuit board spectively These two gates along with the diode action of pendulum light emitting diodes LED133 through LEDI42 make up a 5 by 2 multiplex er The LEDs are physically arranged in the display to form an arc that simulates the swinging action of a pendulum There are 10 LEDs in the pendu lum circuit These are divided into two groups of five LEDs each Note 58 MODERN ELECTRONICS May 1989 the sequence of the numbers on the lines exiting the right side of C13 in Fig 1 A Follow these lines to the IC15 and IC16 NOR gates that drive the LEDs
112. cknowledgment when an error has occurred eoeeo from page 16 ceed 00 volts It operates over a 0 to 5 000 volt range at a specified ac curacy of 10 and repeatability within 5 at a distance of 1 inch from the target The audible visible alarm feature is activated at poten tials that exceed 500 volts Lower voltages are read directly from the in strument s built in analog meter movement Power for the meter is provided by a rechargeable 10 8 volt battery Theinstrument measures 4 7 x 2 x 1 25 inches and weighs just 5 ounces 275 CIRCLE 35 ON FREE INFORMATION CARD May 1989 MODERN ELECTRONICS 69 a More QSO s More QSL s More Fun when you speak their language Add extra spice to your DX QSO s 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 Break the phone pile up with a few carefully chosen words in the DX station s own lan guage 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 eight languages English German French Italian Spanish Portuguese Cyrillic Russian Phonetic Rus sian Phonetic Japanese Phonetic alphabets and eight language dictionary included in this rugged spiral bound manual a MUST for any serious DXer or Contestor Beat the com petition Order yours to
113. cles indicating seconds and minutes respectively Figure 1 C shows the details for Oo00 GImGEUUUEERLNCLLO EENHER UU REDE NICE RUE IR Ce S AREE II MCI EE MUN GS e M t e ert May 1989 MODERN ELECTRONICS 57 just one divide by 60 counter dis play setup Two identical such cir cuits are used in the clock One con sists of JC4 IC5 DS through D10 and LED through LED60 and makes up the seconds counter dis play system The other consists of 1C7 IC8 D12 through D17 and LED61 through LEDI120 and makes up the minutes counter display sys tem Counter C3 and C6 also part of the seconds and minutes counting circuitry are shown in Fig 1 B The divide by 12 counter shown in Fig 1 D is simply an extended ver sion of the standard decade counter used here to count to 12 Its outputs goto 12 hours LEDs that form the in nermost display circle Operation of the clock circuitry is as follows The conditioned 60 Hz square wave from the output of the Schmitt trigger goes to CLOCK input pin 14 of decade counter C 4 The pin 5 output from this IC coupled di rectly to the RESET input at pin 15 to create a divide by 6 arrangement Since the CLOCK OUTPUT at pin 12 of IC14 is high for the first five counts input pulses and is low for the sixth count this output is used to drive the next counter in the chain C13 which is another 4017 decade counter ENABLE input pin 13 of JC 2 is con nected to
114. condition in full sunlight after a time delay of about 15 seconds Resistor R 2 and TEST switzh S2 permit you to check battery condi tion When you push S2 R12 draws a current that exceeds the normal oper ating current of the circuit If the bat tery has sufficient energy to supply this current Q3 is forward iased and PB sounds If PBI doses not sound you know that it is time to re place the battery Construction There is nothing critical about com ponent placement or conductor rout ing in this project Therefore just about any traditional means of wir ing the circuit can be employed If you wish you can fabricate a printed circuit board for the project using the actual size etching and drilling guide given in Fig 2 Otherwise you can purchase a ready to wire pc board from the source given in the Note at the end of the Parts List Al ternatively you can use perforated Fig 3 Wiring guide for printed circuit board Use thisasa rough guide to component layout on perforated board board that has holes on 0 1 inch cen ters and suitable Wire Wrap or sol dering hardware Whichever way you go though it is a good idea to use sockets for the integrated circuits From here on we will assume you are building the project on a printed circuit board Start assembly by plac ing the pc board in front of you in the orientation shown in Fig 3 and fol low this wiring guide exactly when in stalling components
115. creates jag gies and text so boxy that it s diffi cult to tell an A from an 8 Toimprove MCGA s image VGA double scans each line for a total of 400 lines on the screen Essentially the VGA controller takes the infor mation from the first line and dupli cates it on the line directly below it Then it does the same with the second line then the third and so on until 200 lines become 400 Although this doesn t actually improve the mode s resolution doubling of the number of pixels on the screen gives the illu sion of a more detailed display VGA text modes are served up in the traditional 80 column by 25 row format using a 9 by 16 character block Contrast this with CGA s 8 by 8 character and EGA s 8 by 14 char acter block and you ll appreciate what this means in improved display of text characters VGA text can be displayed in either monochrome or with up to 16 simultaneous colors one color per character with 25 or 43 lines Upping the Ante Standard VGA is just the tip of the iceberg of course Most VGA boards go beyond basic VGA to offer better performance greater resolu tion and more on screen colors Let s begin our examination with mode emulators Although the VGA standard em braces all previous IBM video modes a few programs such as Lot us 1 2 3 and MicroSoft Flight Simu lator refuse to work with IBM s VGA emulation of CGA or EGA VGA board makers solve these in Say Yo
116. cussed relies on the power of MIDI connectivity for much of the capabilities displayed Not everyone wants to add a MIDI network or for that matter a keyboard to use his computer to compose and play music If you have a PC or compatible and want to generate some nice music with it the Creative Music System from Creative Labs Inc may be just the ticket The C MS consists of a half size PC expan sion card that contains a complete 12 voice stereo music synthesizer The back of the card which resides on the bracket attached to the backplate of your PC contains a volume control headset jack and a set of standard stereo RCA jacks The jacks allow the output of the card to be plugged into the line in inputs of any standard stereo amplifier or receiver It s the software and the price how ever that make the C MS unusual First the price For 199 you get the card five diskettes of software and three manuals The software contains programs that let you compose your own music play prere corded songs define your own instru ments there are 35 instruments already defined for you and perform a few oth er interesting tasks One of the latter is something Creative Labs calls an intelligent organ This is a screen representation of a keyboard that can be played with left hand auto chord and bass accompaniment from your PC s keyboard The Auto Bass Chord Rhythm ABCR can also be used May 1989 MODERN ELECT
117. d mini mum temperatures and the times they occurred Carefully key in this program just as you did the previous ones and run it You ll see three alternating dis plays giving the three temperatures and times If you don t see these dis plays LIST the program and careful ly check it against the one shown here Rekey any portions of the pro gram that containerrorsin them Use CONTROL S and CONTROL Q to stop and start the listing for this pro gram on the monitor s screen On power up the time is set to 24 00 To set the correct time mo mentarily press and release 53 The display will now show a rotating dis REM write REM divide temperature into 3 digits REM write degree symbol to display F to display play of numbers from 1 to 24 for a 24 hour clock When the correct hour is displayed once again press and release S3 You ll then see num bers from O to 59 rotate on the dis play When the correct minute is dis played again press and release S3 and the program will return to nor mal operation with its clock set to the correct time Program 10 Full Featured Tempwatch Program To test the capability of the Temp watch to store maximum and mini mum temperatures heat and cool the sensor and monitor the results on the display Heat the sensor by holding it near not on a heated soldering iron When the sensed temperature has risen several degrees move the sen sor away from the soldering iron and
118. d remains as such until it is once again gated on by a positive going pulse voltage applied to its gate Normally open pushbutton switch SI provides the gating signal for SCRI through the voltage divider made up of RI and R2 Diode DI puts a small bias on the cathode of SCR to make it work more reliably in this application Light emitting di ode LED is a visual indicator that turns on whenever the line is put on hold SCR is conducting current Construction Owing to the very few components that make up this circuit construction is extremely simple and straightfor ward You can use any mounting me dium that suits your fancy including a printed circuit board perforated board and soldering hardware or a solderless breadboarding block If you wish to fabricate a printed circuit board for this project use the actual size etching and drilling guide shown in Fig 2 A With only four on board components you can easily use a resist pen or dry transfer pat terns to directly etch the board Note that no outline is provided in Fig 2 A for the etch pattern This is because you can make the board as large or small as needed to fit inside the case of any particular telephone instrument For example for my pro totype I needed a board that mea sured inch by 3 inches because that Say You Saw It In Modern Electronics Tip Green Fig 1 Schematic diagram of the ex tremely simple circuit that makes up the telephon
119. day Only 10 00 plus 2 00 per order shipping Supplements available in less used lan guages Dutch Flemish Danish Finnish Swedish Serbocroatian 4 00 per supple ment Be sure to state which language sup plement 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 Tapes available in each of these languages e German e Portuguese French Russian s Spanish Japanese Finnish e Swedish CQ Book Shop 76 North Broadway Hicksville NY 11801 Please send the following Conversation Guide Book 10 Supplements 4 each Dutch Flemish Danish Finnish Serbocroatian Swedish Language Tapes 10 each German French Spanish Finnish Portuguese Russian Japanese Swedish Add 2 for postage and handling in North America Total Name City State Zip EDI TORIAL from page 7 Manufacturing Production 10 4 Services standards quality control etc 7 3 and 16 3 for Other CEO owner professor programmer etc Educationally Modern Electronics readers are naturally expected to have at tained a high level owing to the technical nature of the subject that interests them This rang truer than ever before with 13 3 of respondents to our question n
120. dentifi cation of the conductors as guides Solder a connection between the shield and pin 8 of JC 2 Because module M7 contains CMOS integrated circuits be sure to exercise the normal safety precau tions for handling devices that are subject to damage from electrostatic discharge In addition the display can be damaged by mechanical shock or pressure so handle it with care The M1 circuit board has a single row of 14 holes on 0 1 inch centers for mounting on it an interface cable Say You Saw It In Modern Electronics D p B L r a rail LI r am E E TETTTTTTTTTTTTT A ESTEE BERBEBEIBREIBTIDTIEI JAASIBTIRSBRIRTREIEITTT L LL z LaLLa LE Fig 7 LCD module has one IC that contains virtually all of the module s con troller and driver circuitry connector Unfortunately this con figuration doesn t seem to ma ch any readily available connectors so some improvisation is in order For the sake of convenience a 34 pin ribbon cable is used to connect MI to the circuit board even though many of the cable s conductors will go unused You can buy or make the cable which should be about 5 inches long and have socket connectors at each end Solder a 14 pin single row header to MI On the Microsys circuit board a 34 pin double row header is recommended to match the connec tor and minimize the chances of plug gin
121. der Study which was a four page questionnaire sent to a large sampling of our subscribers A similar study was taken three years ago The latest one reveals that much has changed while at the same time little has changed For example 62 89 o of re spondents said that their interest in elec tronics or computers is primarily related to their employment This is about the same percentage as the older 1986 Study disclosed which was 65 4 About 13 noted that their interest was due to study ing electronics or planning to make it their career as compared to 1986 s 10 4 Given error tolerances in all such sample based studies there s nary a dif ference here from three years ago On the other hand three years made a great difference in responses to questions related to computers Whereas 69 8 of respondents now indicate they plan to buy a computer within the next 12 months only 27 had such buying plans only three years ago Furthermore IBM and compatibles were easily first choice in 1989 with 74 6 of Modern Electronics respondents who indicated they re buy ing a computer affirming this In con trast only 40 4 made this decision in 1986 where this choice still ran first At that time there were also some MS DOS type computers that were not compatible with IBM personal computers and Com modore computers were much more pop ular then which accounts for the differ ence in types of computers chosen Apple Macintosh
122. dwest Electronics Inc 5143 W Diversey Chicago IL 60639 No lilinois Orders Accepted CIRCLE NO 106 ON FREE INFORMATION CARD ELECTRONIC EAVESDROPPING EQUIPMENT DESIGN If you have been looking for the real thing in electronic eavesdropping equip ment design then this book is for you All 58 schematics presented are Sheffield Electronics s surveillance devices Circuits explained Transmitters are pens to 1 mile VOX s including crystal subcarrier carrier current infrared firefly and automobile Demodulators given Cube tap and duplex mains powered transmitters shown 18 telephone transmitters are leech and bat tery types including crystal and subcarrier Chapter on countermeasures Much more This 8 x 11 inch 110 page book is illustrated with photographs Price 30 00 S amp H 4 00 For 1 day processing pay with Money Order or Cashier s Check SEND TO WINSTON ARRINGTON 7223 STONY ISLAND AVE CHICAGO IL 60649 First Class Mail Used 11801 VIDEO PROJECTION TV Convert your TV to project 7 foot picture Easy Results comparable to 2 500 projectors PLANS AND 8 LENS 24 95 Professional Sys tems available Illustrated Catalog FREE MACROCOMA ISMI Main Street Washington Crossing Pennsylvania 18977 Creditcard Orders 24 HRS 215 736 3979 DESCRAMBLERS AI brands Special Jer rold combo 400 and SB3 165 Complete cable descrambler kit 39 Comp
123. e hold function size fitted a ready made but unused mounting bracket in the base of the telephone instrument I selected to house my hold circuit You can make the board as small as inch wide by 1 inches long Wire the board exactly as shown in Fig 2 B Note here that the switch and LED mount off the board When you install DZ and SCRI make abso lutely certain that the former is prop erly oriented and the latter is properly based before soldering their leads to the pads on the bottom of the board If you decide to use a perforated board or a solderless socket instead of a pc board use Fig 2 B as a guide to component layout and orientation and interconnections You need six 10 inch long stranded hookup wires to complete wiring the circuit One of these wires should have green insulation two should have red insulation a fourth should have black insulation and the re maining two can have any other color insulation Strip 4 inch of insula tion from both ends of all six wires Tightly twist together the fine con ductors at both ends of all wires and tin with solder Plug one end of the green and one red insulated wire into the holes la beled GREEN and RED respectively and solder into place Using the holes Special Note This project was designed to fit inside just about any telephone instrument For you to exercise this mounting op tion you must drill holes in the instru ment s housing to permit you to m
124. e resistor into the R1 holes in the circuit board assembly and solder them to the copper pads on the bot tom of the board As mentioned above you have the option of using a three or four posi tion single pole switch in your proj ect for switch 3 if you wish to havea wide range of exposure times A four position switch allows you to be able to include a CALIBRATE posi tion that connects R13 to pin 6 of IC2 to be able to quickly check Sun Guard s accuracy The Time Delay table illustrates the range of exposure times that are obtainable for each of the selected outputs of C2at pins 6 1 2and 3 us ing the specified values for R5 R6 and C in the oscillator circuit If you wish to modify the specified timing ranges change the value of C7 The time relationship is linear with the value of C That is doubling the value of this capacitor doubles the time specified in the table and halv ing its value halves the time It is not recommended that the value of either R5 or R6 be changed from those spe cified for these resistors in the Parts List since the oscillator transistor places a restraint on the maximum and minimum values of resistance used in the circuit Strip inch of insulation from both ends of 11 9 if you are planning on using a single range for your proj ect 5 inch hookup wires If you are using stranded hookup wire tightly twist together the fine conductors at both ends and sparingly tin with sol der Plug
125. ect Catalog for Instruments Accessories and Services publication write to Tektronix Inc P O Box 1700 Dept ME Beaverton OR 97075 1989 General Catalog A complete source book of products for testing repairing and assembling electronic equipment is available from Contact East The 132 page 1989 General Catalog contains list ings and complete descriptions of prod ucts for engineers managers and techni cians including new items in such areas as analog digital oscilloscopes static protection products soldering stations and supplies test equipment precision hand tools and the company s exclusive line of tool kits Also featured are ex panded lines of voice data communica tions test instruments wire and cable aids electronic adhesives and inspection equipment All products listed are fully described including specifications and prices and are accompanied by photo For a free copy write to Contact East P O Box 786 335 Willow St So Dept ME N Andover MA 01845 arem in for Your Electronic Needs Look to U S ELECTRONICS offers Philips ECG semiconduc tors the industry s premier line of replacement solid state devices We carry over 400 different types of transistors including bi polars FET s and MOS FET s high voltage devices such as multipliers divid ers and HV rectifiers diodes SCR s TRIAC s transi ent over voltage suppressors opto electronic de vices including LED displays
126. ects sensitive elec tronic equipment from transient voltage surges on the TV cable or an tenna line and power line This Mod el PTC 209 suppressor can be used to safeguard new TV receivers VCRs cable converters satellite receivers and audio equipment According to Perma Power the circuitry in the suppressor is designed to protect against surges on the coax ial cable without causing meaningful loss of picture signal Accordingly the device can be used on antenna ca ble or satellite lead in cable without creating a snowy picture or loss of the picture even at uhf frequencies This circuitry is also claimed to have a vir tually unlimited lifetime unlike other power line surge Suppressors mi 26 Na X HTTTUHTITETITLITITL Ee sing with completely separate D A converters for each channel that al low the player to perform simultane ous conversions This two converter scheme eliminates the need for com pensation circuitry and improves phase coherence for accurate stereo imaging while 18 bit resolution per mits better reconstruction of the ana log waveforr1 An optical digital output can di rectly couple digital data to amplifi ers and other devices that are equipped with digital to analog converters It also supplies the digital signal in an optical format for transmission over that can wear out or burn out if sub jected to repetitive or high surges Featured are gold plated connec tors to provide hig
127. ee catalog with gives l details of your home study degree programs Phone or write for our Home Study Degree Catalog including enrollment information Phone 213 493 4421 no collect calls name oooO E or write ADDRESS E Grantham College of Engineering 10570 Humbolt Street Los Alamitos California 90720 STATE and ZIP Grantham College of Engineering is accredited by the Accrediting Com mission of the National Home Study Council in Washington D C PME eee Il ELECTRONICS THE MAGAZINE FOR ELECTRONICS amp COMPUTER ENTHUSIASTS MAY 1989 VOLUME 6 NUMBER 5 SS FEATURES 18 Understanding VGA More colors more pixels and extended modes keep VGA at the leading edge of PC graphics technology By TJ Byers 22 The SunGuard Audibly alerts you when cumulative UV exposure reaches a preset limit for safe sunbathing By Anthony J Caristi 22 xxm 28 AC Motor Speed Controller Setting motor speed with optical couplers and a binary counter By Ricardo Jiminez G 33 Making It Count How to use today s sophisticated frequency counters By Bill Owen 38 Microprocessor Control With BASIC Conclusion Adding an accessory to last month s Microsys development unit to create a smart thermometer By Jan Axelson amp Jim Hughes 46 Put Your Telephone On Hold Low cost add on circuit gives any telephone instrument a hold feature By Andrew VanLoenen 50 A Smart Car Relay Provide
128. elligent Organ Version 1 04 Copyright c Creative Music Lab 1988 All rights reserved PTT Zi help BW play replay non stop default YJ load save rore CMS s music notation is easy to enter with a word processor but it s not very intuitive as this partial listing demonstrates With a thousand sounds to choose from selecting any particular one is eas ier than it might seem at first The Ma trix 1000 s front panel has a 3 digit LED display in the middle flanked on the right side by a 10 key keypad with additional keys for plus minus and enter On the Left of the display is a volume control LED indicators for Patch Channel Fine Tune Units Data Dump and Ext Funct as well as two push buttons la beled Select and Bank Lock The particu lar function is selected with the Select button which cycles through the various indicator LEDs Fine Tune and Units are used to tune the Oberheim instrument to others that may be included in your band or MIDI setup The Data Dump and Ext Funct are MIDI operators Channel lets you as sign MIDI channels 1 through 16 to in dividual patches A patch or sound it self is selected by first cycling the LEDs with the Select button until the one over Patch is lit The Matrix 1000 is accompanied by a double sided sheet list ing patch numbers and names The patches are in 10 banks of 100 sounds each These banks are roughly grouped into simila
129. ephone Transmitters Phone Snoops Bug Detectors More Catalog 1 00 XANDI ELECTRON ICS Box 25647 JJ Tempe AZ 85285 5647 CB Tricks of the Trade book CB repair tricks and tuning tricks Send 19 95 to Medicine Man CB P O Box 37 Clarksville AR 72830 PROFIT TOP QUALITY SOLDERLESS BREADBOARDS AND DIGITAL MULTI METERS FOR LONGTERM QUANTITY BUYERS STORES ARE MOST WEL COMED CTI 1418 UPFIELD SUITE 127 CARROLLTON TX 75006 DESCRAMBLERS Test Equipment Elec tronic Books etc Send 2 for info to B and R Enterprises P O Box 662 Portage MI 49081 ELECTRONIC COMPONENTS Free 192 page catalog including capacitors resistors relays connectors soldering equipment and supplies Box 699 Mansfield TX 76063 1 800 992 9943 WIDE range Tunable Ultrasonic Receiver Long Range Listening TUBE Bug detec tor BC DX Booster Scanmate Voice coder decoder and other interesting products Cata log 1 00 KRYSTAL KITS P O Box 335 BENTONVILLE AR 72712 ELECTRONIC Test Equipment Laboratory Equipment Experimenter s Items Indus trial and Government Surplus and priced Cheap Send 50 for Catalog to Lehman R D 1 Box 580 Wrightsville PA 17368 FCC Commercial General Radiotelephone License Prep Course by correspondence 60 individual lessons 89 50 Payment plan Also BASIC COMPUTERS 39 50 cer tificates Details free AMERICAN TECH NICAL INSTITUTE Box 201 Cedar Moun
130. ern Electronics May 1989 MODERN ELECTRONICS 73 Ow ms THER miSTOR M COPPER wie Cow E 15 So 8 100 125 180 ids 160 w M 2 4 H vi v w E Temperarure F Fig 6 Graphical depiction of howa ther mistor temperature compensates a meter coil 5 circuit the relay does not energize As the thermistor warms up as a result of the current flowing through it its resistance eventually falls to a point where the cur rent flow is sufficient to energize it De pending on the thermistor and relay used the delay period can range from a frac tion of a second to several minutes The thermistor I used had a room tempera ture resistance of about 2 000 ohms and yielded a delay of about 15 seconds The basic Fig 5 circuit can be easily modified to drive high current relays All that is required is to monitor the current flow with an operational amplifier The output from the op amp can then be used to switch on a power transistor that in turn drives the relay Since ambient temperature can vary considerably a thermistor is not suitable for use if you require a precision repeat able timing interval For applications that are not critical the thermistor ap proach provides one of the simplest tim ing circuits available e Temperature Compensation A ther mistor s NTC makes this device very use ful as a temperature compensating de vice For example a thermistor can be used to correct the PTC error o
131. es typical distance to trans mitter plots for counting the frequen cy of a host o common r f sources Measurements were made with our assembled project counter using an 18 inch telescoping whip antenna connected to the device s input Ob viously distances in which accurate counting could be accomplished would be greater if an antenna made expressly for the radio frequency to be picked up were used Other vari ables here would include transmitter output power transmitter height and the counter s sensitivity to the frequency being captured With a 1 watt 2 meter radio trans mitting at rearly 150 MHz being counted from 75 feet away it s shown that a telescoping whip anten na can be readily used when the source isn t far away The whip was fully extended in this case it would be collapsed as frequency increased A rubber duck antenna though Say You Saw It In Modern Electronics Distance in Feet conveniently small causes the effec tive counting range to decrease as much as 50 percent in some cases For scanner frequency counting broad band antennas designed for these frequencies will provide greater range than the whip used here There are a number of sources that sell such scanner antennas The public service frequencies transmitted locally are favorites for frequency catching It s legal to sniff out any frequency you know punch it up on a scanner if it s in its range and listen in on the transmission
132. f the cop per wire in the coil of an electromechani cal meter movement or the winding of a relay motor or generator Figure 6 is a V RZ Vour o D Vour gt m ud M 3 3 T A Q TEMPERATURE gt a ME 2 Oo i TEMPERATURE 3 Fig 7 Voltage outputs from a linear thermistor network graphic depiction of the resistance of a copper wire meter coil as a function of temperature The resistance of an NTC thermistor is plotted on the same graph Figure 6 also shows the combined re sistance of the coil and the thermistor when the latter is connected across the former As this illustration clearly re veals the thermistor almost eliminates the meter coil s temperature error The curves shown in Fig 6 are adapted from NTC Thermistors a brochure pub lished by Sensors Scientific Inc Linear Thermistor Networks Parallel connection of a thermistor across the coil of a meter movement that provides the linear curve shown in Fig 6 is a simple form of a linear thermistor network This and many other thermistor resistor net works can be made from individual com ponents or be purchased as integrated networks For example Fenwal Elec tronics makes a series of miniature linear thermistor networks that incorporate two thermistors and two resistors con nected as shown in Fig 7 This circuit produces an output voltage that varies linearly with temperature The output voltage across R2 i
133. f the leads of the battery snap connector and tin with solder Plug the black insulated negative connector lead into the hole labeled B1 in the board and solder it into place Crimp and solder the red insulated positive lead to one lug of S7 Then plug the free ends of the wires coming from the buzzer into the PB1 holes making certain that you observe correct polarity and solder them into place Be sure to connect the free ends of the R5 wires to the lugs of this poten tiometer so that clockwise rotation results in increasing resistance Otherwise you will not be able to Say You Saw It In Modern Electronics properly calibrate the circuit Crimp and solder the free end of the wire coming from hole S3w to the common wiper lug on this switch if you are using it Then crimp and sol der the free ends of the wires coming from holes 6 3 2 and 1 to the remain ing lugs of theswitch in the proper se quence Finally crimp and solderthe free ends of the wires coming from the S2 holes to the lugs of the push button switch House your project inside a small clear plastic enclosure that is capable of preventing sand and other con taminants from entering Use of a clear plastic enclosure is mandatory to permit the solar cell to get full ex posure from the sun Machine the enclosure by drilling mounting holes for the three switches two switches if you opted to omit 3 potentiometer R5 and the clip that will hold the batte
134. fine emery paper to sand down to bare shiny metal and an outside tooth lockwasher between the ring lug and metal of the chassis Installation amp Use The Smart Car Relay is extremely flexible and can be used in a wide va riety of applications as mentioned above Of course the COMMON NORMALLY CLOSED and NORMALLY OPEN wires from the project con nect to the device being controlled as needed Figure 2 illustrates the connections required to provide typical power antenna control With the project wired into your vehicle s electrical system as illustrated whenever you turn on your radio the antenna will telescope upward to permit radio re ception Turning off the radio will cause the antenna to retract Before making any connections to the anten na however make sure that the proj ect is compatible with it Illustrated in Fig 3 are the connec tions that must be made to permit driving of two speakers from two audio outputs Though a general dis cussion of this arrangement was de scribed above note here that the speakers shown do not have a com mon ground Therefore all returns must be made separately This re quires five relay contacts altogether Hence an additional four pole relay is needed In this arrangement the 12V IN PUT lead connects to the 12 volt source in the vehicle s electrical sys tem and the 12 volt input lead from one of the audio units goes to 90 MODERN ELECTRONICS May 1989
135. frequency The divide by 60 counters are each made up of two 4017 decade count ers a units counter and a tens count er with the COUNT OUTPUT at pin 12 of the units counter connected to the CLOCK input at pin 14 of the tens counter The counter pairs for the seconds and minutes counters in Fig 1 B are C3 IC4 and C6 IC7 re spectively The pin 5 outputs of C4 and C7 are connected to the RESETS at pin 15 of both counters in both cases This forces both counters to be in proper sequence at all times Tens counters C4 and C7 in the seconds and minutes counting cir cuits respectively have their outputs inverted by hex inverters C5 and C8 Circuit details are shown in Fig 1 C The outputs from the inverter chips are connected to the cathode side of each group of 10 LEDs by an isola tion diode For the seconds counter circuit these diodes are D5 through D10 and for the minutes counter they are numbered D 2 through D17 Say You Saw It In Modern Electronics After both counters are reset the pin 3 outputs of both C3 and C 6 are high This turns on the first LED in the first group of 10 As the units counter is clocked the LEDs come on in sequence thereafter When pin 3 of either counter chip goes high so does COUNT OUTPUT pin 12 thus advancing the counter one increment Now the second group of LEDs comes on This pro cess continues until the fifty ninth count is reached Then when pin 1 of the counter goes low
136. g cual 24 hour cocks with timar ali mode squelch and noise blankers a a ge front moi ntad sp2ak24 110 volt AC or 12 vo t DC ope etion with the DCK 1 c ble kit and 113 174 MHz VHF cepability wath VC 10 opxi on Optional Accessories R 2000 e VC 10 VHF converter e 2CK 1 DC cable kit for 12 voit DC usa R 5000 e VC 20 VHF converter e VS 1 Voice module e DCK 2 for 12 volt DC operation e YK 88A 1 AM filter e YK 88SN SSB filter e YK 88C CW filter e MB 430 Mounting bracket Other Accessories e SP 430 External speaker e SP 41 Compact mobile speaker e SP 50B Mobile speaker e HS 5 Deluxe head phones e HS 6 Lightweight headphones e HS 7 Mini headphones KENWOOD KENWOOD U S A CORPORATION 2201E Dominguez St Long Beach CA 90810 P O Box 22745 Long Beach CA 90801 5745 NO 95 ON FREE INFORMATION CARD
137. g it in incorrectly Use an indelible marker to place an identifying dot near pin 1 of each header On M1 pin l is nearest the corner of the mod ule s circuit board On the Microsys circuit board pin 1 will be the pin that is nearest the pin 1 arrow when the connector is plugged in Plug the ribbon cable s connectors into the headers matching pin 1 to pin 1 on the connector and header at Fig 8 LCD module used in this project can display message of up to 16 char acters using letters numbers or other symbols a a S May 1989 MODERN ELECTRONICS 41 Fig 9 Circuit board transformer and batteries mount on the floor of the en closure serial port connector and sen sor cable exit through rear panel each end On M1 plug the socket nearest the pin arrow into pin on MI s header One entire row of sock ets on the connector as well as the bottom three sockets of the other row are not used in this project Once you are satisfied that every thing physically meshes together dis connect the cable Then install R20 on the circuit board and wire the cir cuitry shownin Fig 6 To wire S2and S3 prepare three 8 inch and one 4 inch lengths of hookup wire by strip ping inch of insulation from the ends of each Twist together one end of the 4 inch wire and one end of one 8 inch wire and crimp and solder the twisted pair to one lug of S2
138. ged to a new location even If it s just one pixel away Audrey Thompson Editor Aldus Corp Seattle WA Output Quantity Channel SUBTOTAL Shipping Add 3 00 per unit COD amp Credit Cards Add 596 L TOt California Penal Code 4593 D forbids us from shipping any cable descrambling unit to anyone residing in the state of California Prices subject to change without notice PLEASE PRINT Il agree with these observations on sev eral points and disagree on one As I men Name tioned column guides are created with Address NE SN the Column Guides choice from the Op State Zip Phone Number CEN tions menu Ruler Guides created by O Cashier s Check O Money Order 0 COD O visa 2 Mastercard pulling them out from the sides and top Wodh BL aet mmt with the mouse however do affect the Exp Date 90 Signature n flow of text Horizontal guides pulled from top or bottom when used with the Snap To Guides option limit column depth when manually flowing text Text can be pulled past these guides but will normally stop at a horizontal guide The comments about placing graphics first are quite correct I wasn t aware that I had to move a graphic before PageMak er would reflow around it This feature Continued on page 83 Say You Saw It In Modern Electronics FOR OUR RECORDS DECLARATION OF AUTHORIZED USE
139. graphic displays Your plotter uses two motors an doe n and gear mechanisms to position and activate the plotting pen both manually and under program control You go on to use your computer to program and control a diverse array of robotic systems you create with NRI s remarkable Robotic Discovery Kits Robotics comes to life as you see real world industrial control principles in action Your NRI Robotic Discovery Kits come complete with everything you need to create working moving robotic systems You get structural members motors gear drives sensors scanners potentiometers plus a special Robotics Interface that links the robots you build to your computer teachable robotic arm is the most complex robot model you construct Once you manually put the robot through a sequence ol operations it will remember these steps and perform them whenever asked Together your computer and the robotic devices you construct become fully integrated automation systems programmed by you to do the types of operations and tasks performed in today s industrial environments Tasks such as plotting polar coordinates to create graphic displays of numeric data sorting different size objects and routing these objects to separate containers even performing a preprogrammed sequence of opera tions again and again just as robots now do on manufacturing lines Nothing is left out nothing is left to chance
140. h level conducti vity and resistance to corrosion and carbonization The device provides protection against all three ways that surges from lightning or switching can travel on the power line in the normal and both common modes Rated at 1 800 volts the device has a let through potential of less than 2 volts It plugs into any grounded ac a fiber optic cable A high speed lin ear motor access system is used in the player and a high resolution laser in creases pickup accuracy Features include random play 32 step random access program ming skip and index skip auto cue repeat A B repeat music scan 5 3 disc accommodation shuttle search 20 segment output signal me ter to 50 dB timer play large in sulator feet headphone jack with separate volume control illuminated disk window and multi function wireless remote controller 410 CIRCLE 32 ON FREE INFORMATION CARD receptacle It has a fail safe shut down feature that automatically dis connects the power line from the pro tected devices should the device ever wear out or burn out Dimensions of the device s plastic case are 44 x 3 4 x 24 and weight is 11 ounces CIRCLE 33 ON FREE INFORMATION CARD Marine Range Extender The RFTR M Signal Intensifier from Electron Processing Inc Medford NY is a receive preamplifier that is said to improve the coverage of vhf marine radio transceivers by ampli fying received signals It installs in the
141. h of any input signal ap plied to a frequency counter let s look at the compact counter for which construction plans were pre sented Each of its two frequency range modes has a different maxi Making It Count Using a frequency counter requires some basic understanding of the instrument s capabilities and how it can be applied mum input signal it can accept with out damage Range A which has a frequency range of 10 Hz to 12 MHz and a l megohm input impedance has a maximum input Specification or damage level of 100 volts ac plus dc Range B which covers 10 MHz to 2 2 GHz and has a 50 ohm impedance in put hasan input limit of only 2 volts Imagine what a disaster it would be if the range switch was accidentally changed from A to B while in putting say a 50 volt signal There are other unfamiliar ele ments of concern when operating a frequency counter For example its input sensitivity might change with frequency Consequently one should have some idea of the approx imate frequency to be counted Fur thermore signals have to be properly coupled between the counter and the device being checked Ignoring the foregoing the counter might display no reading an unstable reading or even a wrong count None of the foregoing operating considerations can be considered to be outrageous However they may indeed be somewhat disconcerting to anyone not used to working with high frequencies the major
142. he 1 Hz di vider that drives the remainder of the clock s circuits Pc boards for this project are dou ble sided You can make your own boards using the actual size etching drilling guides for the pendulum and main boards shown in Fig 2 and Fig 3 respectively Keep in mind that home made boards will not have plated through holes and thus re quire that you solder all component pins and leads to the pads on both sides of the board If you prefer not to make your own pc boards you can obtain ready to wire pc boards from the source givenin the Note at the end of the Parts List Wire the pendulum board first re ferring to Fig 4 for details Note The views shown in Fig 4 and Fig 5 are fromthe top of the board Install the sockets or Soldercons first but not the ICs themselves in the indi cated locations This done identify the cathode leads of the 10 light emit ting diodes that make up the pendu lum Install these LEDs on the board in the indicated locations and solder their leads into place Note that the cathode K leads all face toward the top of the board Position the LEDs so that the bottoms of their cases are auniform X inch above the surface of the board Plug the pins of the three switches into the holes identified by the leg ends S1 S2 and S3 and solder into place Then install the two diodes near the IC16 socket taking care to properly orient each before soldering their leads into place 62
143. hermore there s now plenty of low cost effective MS DOS software available Additional ly adults and their children are increas ingly more computer literate In spite of the lower Business Profes sional use percentage 8 8 however about twice as many readers plan to use the computer they plan to buy for busi ness professional applications This is because the total number of expected Modern Electronics computer purchas ers in 1989 is so much greater than it was in 1986 about 49 000 vs 20 000 read ers Soextrapolating the much higher fig ure with a moderately lower percentage against the entire Modern Electronics cir culation yields a much higher number of buyers in this case double the number Among subscribers who plan to buy test instruments this year 68 9 say they ll be buying digital mutltimeters within the next 12 months vs 1986 s 11 and 64 noted that they plan to buy dual trace oscilloscopes vs 1986 s roughly 16 Among them 47 8 plan to buy test instruments mostly for busi ness professional purposes This appli cation question wasn t posed in 1986 Respondents involved in company purchasing were asked on a multiple Say You Saw It In Modern Electronics choice question how many employees were in the company Except for the ex tremes of the smallest number 1 to 9 and the largest groups 1 000 and over and 250 to 999 the figures closely matched 1986 s Respondents who worked
144. i simply indicate your choice on the reply form provided As a member you agree to purchase af least 3 books within the next 12 months and may resign at any time thereafter ironciad No Risk Guaran tee If not satisfied with your books return them within 10 days without obliga tion e Exceptional Quality All books are quality publishers editions especiaity selected by our Editorial Board 1969 ELECTRONICS BOOK CLUB Blue Ridge Summit PA t 294 0810 All books are hardcover uniess number is followed by a P for paperback Publisher s Prices shown FREE when you join pM COMPACT Delton T Horns Projecis WSC PLAYER All Time Favorite E ano SOUNESTATE TYS we aa 15 Easy Electronic x i Projects From Delton T Horn gt a ronic Projects fa Projects you can build some 7 95 Ew A unique some old favorites from value l the author s vast treasury of A v 909090606096 0909000900000009000000000000000209 electronics know how 2707 26 95 Counts es 2 It ELecraanucs Baar Cou THE GIANT BOUL OF ELECTRONICS Biue Ridge Summit PA 17294 0810 PROJECTS Please accept my membership in the Electronics Book Club and send the 5 volumes listed ELECTRONICS d bleg below plus my FREE copy of Delton T Horn s All Time Favorite Electronic Projects 3105P FIX IT BOOK 1 1 billing me 3 95 plus shipping and handling charges If not satisfied may return the books within ten days without obligat
145. ility of a thermistor to function as a surge protector I connected one in series with a 100 ohm resistor and a chart recorder When 10 volts was con nected across this network the curve ub RELAY Fig 5 A simple thermistor time delay circuit shown in Fig 4 was generated by the re corder Three seconds after application of the voltage the current through the circuit reached 35 milliamperes After 30 seconds the current reached 58 milliam peres Various other thermistors will pro duce different time delay curves A possible application for a thermistor surge suppresser is to protect laser diodes and other very delicate semiconductors that can easily be damaged by very brief current spikes The Fig 4 curve shows a current level close to that required to op erate many CW laser diodes e Time Delay Circuits The reduction of resistance that results from self heating that permits thermistors to serve as surge protectors also allows them to function in simple timer circuits Shown in Fig is a simple circuit I tried to verify this applica tion Here resistor R s 100 ohm value limits current through the thermistor and relay The low voltage relay pulls in when its coil current exceeds approximately 20 milliamperes at 9 volts Radio Shack s Cat No 275 005 relay works well in this circuit the company s Cat No 275 232 reed relay should also work When power is first applied to the Fig Say You Saw It In Mod
146. ill not turn on when it is supposed to If a LED is installed in the wrong polarity the group of 10 LEDs in which it appears will will light rather brightly but the reversed one will not light at all If more than one second minute or hour LED lights when the clock is first powered up press and hold the SECONDS HOLD button and advance the minutes and hours LEDs by pressing the appropriate SET but tons This should clear out the count ers and allow them to operate in the normal manner Once you have your clock working as it should power it down Secure the two circuit board assemblies in place with No 6 x inch wood screws Then assemble the enclosure Set the clock in the location where it will remain and plug its line cord into a convenient ac outlet Now set the time To do this press and hold the SECONDS HOLD button and then the HOURS SET button until the appropriate LED in the hours ring islit Release the HOURSSET but ton but not the SECONDS HOLD but ton and press and hold the MINUTES SET button until the appropriate min ute LED is lit Go one minute past the actual time before you release the MINUTES SET button Continue to hold the SECONDS HOLD button until the exact second arrives to release it Your clock will now continue to count off seconds minutes and hours with the precision of the ac line and will continue to do so for as long as ac power is applied to it When the time comes to set the clock forward or
147. implify application of the 4c materials to pif connectors that are difficult to treat with the company s 4c3m rub on crayon applicator system The 4c materials are said to overwhelm intermittents and po tential intermittents by providing thousands of times as many micro scopic metal to metal contact paths as connections without it Each contact point is encapsulated in a corrosion protective nontoxic lubri cating film CIRCLE 29 ON FREE INFORMATION CARD 8 mm Camcorder Nikon s new Model VN 830 point and shoot 8 mm camcorder features an ultra compact design 6X power zoom lens with macro close up auto focus with manual override switch TTL auto white balance and vari able shutter speeds up to ooo second Features include a 4 inch CCD im Say You Saw It In Modern Electronics age sensor with 270 000 pixel resolu tion fast 9 lux minimum lens auto matic exposure edit search still frame and slow motion playback macro close up lens unidirectional microphone and built in electronic viewfinder tilts up for low angle shooting Such data as function mode and alarm indicators are dis played on the viewfinder s screen Also the VN 830 lets you record date or time with the picture Advanced editing functions built into the camcorder include edit search a flying erase head a linear tape counter and an edit switch Edit search simplifies reshooting of scenes by allowing the user
148. ion and have my membership cancelled agree to purchase at least 3 books at regular Club prices plus shipping and handling during the next 12 months and may resign any time thereafter 06000009000060000 06000000000000000090900b 5 66060909000090090000060000000060006000090990900950 3133 15 95 1367P 18 95 o0 TEL LR Address SE E Ve i with b sp State _ madii Zip Phone 40 ad Signature 1 1 1 1 Milo adt Valid for new members only Foreign applicants will receive special ordering instructions b ED xs Canada must remit in U S currency This order subsect to acceptance by the Electronics 2900 34 95 2885 516 95 Book Club MDNES589 1532P 810 95 303 24 95 e 096060 90 0 00009000000900 000009000000000200000000900009099 09 Counte as 2 Computers Understanding VGA More colors more pixels and extended modes promise to keep VGA at the leading edge of PC graphics technology By TJ Byers users were singing the praises of IBM s Enhanced Graphics Adapter EGA that offered real ben efits in video display of text and graphics Today though even en hanced versions of EGA hardware are being elbowed into the back ground by the new kid on the block IBM s VGA which stands for Video Graphics Array VGA s 640 by 480 high resolution screen is 37 percent better than EGA Its great for display of text and general purpose graphics but it really shines f
149. is just such an animal the Oberheim Matrix 1000 The Matrix 1000 is a small 19 inch wide rack mountable synthesizer Though it doesn t have a keyboard it certainly doesn t lack preset sounds There are have 1 000 of them Many of these are slightly strange at least to me sounds rather than emulations of musical instru ments Others such as 183 the VIOGI TAR are mutant combinations Of course beauty isin the ear of the compos er to paraphrase a cliche Setting up and using the Matrix 1000 is easy The back panel has sockets for the power cord MIDI in out thru connec tors and astandard A inch plug such as a guitar cord Plug in the power connect the MIDI intoa MIDI OUT suchas a se quencer or as in my first experiments a MIDI keyboard then connect the audio out from the unit to an external amp Turn on everything then set the key board to transmit on a MIDI channel While I had misplaced the meager doc umentation that came with the Casio MT 540 keyboard which was part of the CMS 1 MIDI Studio I reviewed last month it still took less than two minutes of pushing buttons before I realized that I had to select MIDI on the Casio s CHORD MIDTI switch and press one of the sound effects buttons that are co labeled CH1 CH2 CH3 and CH4 I was savvy enough though to set an initial patch another name for sound on the Oberheim before I started to play with the Casio Creative Music System s Int
150. it No 2 12V audio unit No 1 NORMALLY OPEN K1 Left 4 No 1 Left 34 No 1 K1 K1 Right 4 No 1 Right 34 No 1 K1 LEGEND p Normally open K1 12Vdc Aux relay y Normally closed K1 Left No 2 Left speaker Left K1 No 2 K1 Left No 2 Right speaker Right K1 No 2 Fig 3 Automatic speaker switching between two audio units and single pair of stereo speakers As shown in picto rial this arrangement requires an additional auxiliary relay controlled but not less than No 18 in any application Tightly twist to gether the fine wires at all ends and sparingly tin with solder These wires are for the coil and contacts of the re lay and for the conductors that con nect from the bridge rectifier to the vehicle s electrical system and device being sensed and controlled Use an all metal enclosure or a plastic box that has a removable alu minum top panel as an enclosure for the project Select one that accom modates all components that make up the project including any relays that might be used Machine the en closure for mounting the circuit board assembly and routing the free ends of the conductors that are to connect to the outside world Drill two more holes in the floor of the en closure for mounting the project in side your vehicle If you are using an all metal enclo sure line the
151. it to the wires Fig 2 Plot of thecurrent flow through a thermistor as it is being touched by a finger and after finger is removed 72 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics Fig 3 Examplesof two wafer and a mini ature bead thermistors The wires emerging from one end of each bead are then cut to form individual ther mistors The ceramic bead is then usually encapsulated in a protective glass or epoxy coating Wafer and surface mount chip ther mistors are made by casting thermistor paste into thin sheets The paste is then fired in a furnace and coated on opposite sides with silver or some other conductive material If they are required external leads are soldered directly to the silver terminals Wafer thermistors may be giv en a protective coating of epoxy The sensitivity response time and re sistance range of a thermistor are deter mined by the metallic oxide from which it C A b 2 w a at 2 v Io SECONDS Fig 4 Plot of thermistor current versus time is formed its size the encapsulant used and the presence of external leads For example external leads and a thick en capsulating layer can slow down a ther mistor s response time So if rapid re sponse time is important in a given appli cation the active element and its leads and encapsulant should have as little mass as possible This will permit the ac tive element to rapidly respond to very
152. ity hookups of the equipment being sensed About the Circuit Shown in Fig 1 is the complete sche matic diagram of the Smart Car Relay s circuit The heart of this cir cuit is full wave bridge rectifier RECTI which can bea common rec tifier module or four separate silicon power diodes connected into a bridge configuration with the individual di odes connected together as shown Note that the four diodes are wired so that they are in a series parallel ar V ERES Vua A20 oo ee ee c ewteo SSS SS Hoe SSS ac 12Vdc equipment PEL Too Y closed Common to Normally open pid K1 1N4001 PARTS LIST D1 1N40001 or similar 50 PIV l ampere silicon power rectifier F1 Fuse see text K 1 12 volt dc 120 ohm or greater relay with 10 ampere or more con acts see text Q1 2N3906 or similar general purpose pnp transistor R1 47 ohm watt 10 tolerance resistor RECT1 50 PIV 25 ampere bridge rectifier assembly or individual power diodes see text Misc Printed circuit board or perfor ated board and suitable soldering or Wire Wrap hardware see text suit able enclosure see text in line auto motive fuse holder small rubber grommets 4 spacers lettering kit machine and sheetmetal hardware heavy duty stranded hookup wire solder etc Fig 1 Complete schematic diagram of Smart Car Relay s circuitry This is the simplest circuit configuration Other
153. jobs building programming and servicing the robotic systems in use today Now unlike any other school NRI offers you training that prepares you to take advantage of these new opportunities training that gives you the practical know how and the hands on skills to advance on the job Or start a new career as a robotics and industrial control technician Two tasks fre i quently performed by robots are measur ing and sorin be it sorting eggs or eliminating scrap from a production line You build this sorting system then Poor it to accept short and long blocks measure these locks and move them to the correct storage bins The powerful XT compatible computer you build becomes central control for the robotic systems you construct As an integral part of your NRI hands on training you build a fully IBM XT compatible computer from the key board up You assemble the power supply install the 514 floppy disk drive and attach the high resolution monitor Most important of all by performing meaningful tests and demonstrations at each stage of assembly you come to a full under standing and appreciation of the microprocessor technology that makes today s robotics applications possible But that s just the beginning Robots are often used to display in graphic form the results of sd computer calculations i The polar coordinate plotter you build accepts analog data and position ing commands to create
154. k mount kit 595 CIRCLE 27 ON FREE INFORMATION CARD Amplified Speaker From Naval Electronics Tampa FL comes the Model HTS 1 a tiny amplified speaker for users of hand held radio and personal stereo equip ment The system s die cast enclo sure houses a 3 5 oval speaker that is driven by a built in 10 dB 1 watt into 4 ohms amplifier Power for the am plifier can be gotten from an internal rechargeable Ni Cd battery the charger is built in or any external 6 to 15 volt dc source When the sys tem is operated on battery power a special automatic shut off feature kills power to the amplifier whenever there is no audio input receiver is squelched for more than 10 seconds to conserve power Setting the power switch to off bypasses the amplifier 14 MODERN ELECTRONICS May 1989 and connects the input jack directly to the speaker The system s rated frequency range is 200 Hz to 15 kHz its input impedance is 100 ohms and maxi mum input signal level is 400 mV Features includea LED status indica tor tilted base for tabletop use a 5 ft cable with mini plugs and a stereo to mono converter 29 95 CIRCLE 28 ON FREE INFORMATION CARD Permanent Repair for Intermittent Connections Now available from Micro Circuits Co Inc New Buffalo MI for per manent repair of intermittent con nections is 4c3a in aerosol can form The aerosol addition to the com pany s line of products was devel oped to s
155. less than 1 full sun as the day progresses Of course any haze or clouds in the sky will obscure filter the sunlight to some degree resulting in less than 1 full sun of intensity Under 1 full sun conditions PC generates about 0 3 ampere or 300 milliamperes of current Because there will be variations in output from one solar cell to another under identical detecting conditions Sun Guard s circuit is equipped with cali bration potentiometer R4 that allows you to adjust for the particular solar cell used in the project The open circuit output generated by PCI about 0 5 volt is of no con sequence since it is the generated current that is proportional to the in tensity of the sun s energy To pro vide a voltage that is proportional to the detected energy PC1 is loaded with a very low 0 2 ohmresistance by R1 The potential that appears across RI will be approximately 60 milli volts under conditions of 1 full sun and will vary linearly with changes in sun energy intensity 45 millivolts at sun 30 millivolts at 4 sun and so on To provide a usable voltage source for the circuit as well as a means for calibrating the solar cell JC A is connected as an operational ampli fier with its gain determined by the values of R2 R3 and R4 Potentio meter R4 covers a range that is suffi cient to provide an output at pin 8 of IC1 of 5 5 volts under conditions of 1 full sun exposure of PC Once R4 is adjusted for this ou
156. lete satellite de scrambler kit 45 00 Free catalog MJO IN DUSTRY Box 531 Bronx NY 10461 0531 VHS VCR Repair Solutions Volumes 1 11 III IV Each contains 150 symptoms and cures cross reference chart free assistance Each 11 95 any two 19 95 any three 29 95 all 39 95 Eagle Electronics Box A 52053 Locks Lane Granger IN 46530 FASTEST Color TV Repairs anyone can do 100 priceless secrets 2 00 for sample Check mate Communications PO Box 11 0808 ME Brooklyn NY 11211 ELECTRONICS TUBES Name Brands New 80 off list Kerby 298 West Carmel Drive Carmel IN 46032 DETECTION Surveillance Debugging Plans Kits Assembled Devices Latest High Tech Catalog 5 DETECTION SYSTEMS 2515 E Thomas 16 864H Phoenix Ari zona 85016 ELECTRONIC fish detector It brings the ageless pleasure of fishing right into the elec tronic age And it s low cost is within the reach of everyone Send 5 00 and SASE for info to James Tyler 107 51 139 St Jamaica NY 11435 u SURVEILLANCE Debugging Protection Worlds largest new catalog 5 00 Kits As sembled All price ranges TECHNOLOGY SER VICES 829 Ginette Gretna LA 70056 DIGITAL project build yourself complete electronic car dashboards Send 1 refun dable for details MODERN LABS 2900S Ruisseau Saint Elizabeth QC JOK 2JO Canada 86 MODERN ELECTRONICS May 1989 MU ORUM ee Se VOICE Disguisers FM Bugs Tel
157. liquid crystal display module M Existing ac motor Sl Spst momentary action pushbut ton switch S2 2 position slide or toggle switch 9 volt dc 150 mA plug in power supply just the opposite effect EPROM C4 an 87C64 chip is used here to represent the 16 steps of the controller that are counted off in the DISPI LCD display The EPROM s program is given in the ta ble Decoder C6 converts the output from the EPROM into a format that can be used by DISPI Note that the Q4 output at pin 16 of C4 is coupled to input pins 15 and 24 of DISPI through XOR gate JC7A Note The other XOR gates in C7 are not used in this circuit Schmitt trigger inverters C2A and C2B make up a 40 Hz oscillator that drives the LCD s backplane and decoder C6 s phase input at pin 6 ac cording to the recommendation giv en in the CD4543 s data sheet Your choice of triac for Q1 will de pend upon the amount of current re quired to operate the motor The greater the demand of course the higher should be the current rating of the triac chosen This current rating should be at least 1 25 times the max imum amount of current the motor will normally draw A good starting value for the par allel resistor network made up of R11 through R74 and any other net works you might incorporate into 32 MODERN ELECTRONICS May 1989 Fig 2 Typical waveforms A 117 volt rms sine wave from ac line B load voltage if triac iu
158. ll toll free 1 809 321 2155 in Ohio 1 800 362 2105 or mail in CIRCLE 98 ON FREE INFORMATION CARO Please send your independent study catalog For your convenience CIE will try to have a representative contact you there is no obligation Print Name Address Apt City State Zip Age Area Code Phone No Check box for G I Bill bulletin on Educational Benefits Veteran Active Duty MAIL TODAY Just call toil free 1 800 321 2155 in Ohio 1 800 362 2105 AHigh performance KENWOOD pacesetter in Amateur Padio Laa SELECTIV TY SaL BOTCH AUTO 8 s 3 px eo y VLL y ti QE Fi Fi LM VOICE TIMER DIM W 10 02 i h i hr tt fe m2 2 J 3 LE ni oL I ANT d d COMMUNICATIONS RECEIVER e Ko ET i MODE KEY r RESETS a x l M3 NB i SHIFT F FF CLOCK1 OFF CLOCK 2 cti Hea 4 F kc umm oo a HOU f _ e LSA uss CW AM FM Mens ad OM OFF TIME pre canz r i ra Tus E A B FLOCK i e T Fas P STEF Ang S r 3 J D ELLES A 009 CH eJ receivers mi 4 i 4 M ad VELIM i uU Scan the entire frequency range from 100 kHz to 905 MHz with Kenwood s R 5000 R 2000 and RZ 1 Listen in on foreign music news and commentary Monitor local police fire and other public gt safety services as well as the Marine channels and the many other services 50 MHz and above The VHF the R 5000 and R 2000 R 5000 The
159. lockout and delay Selectivity is 55 dB 25kHz audio output is 450mW maximum Snap on battery pack gives full powered portable scanning Assd BC 100X LT 3 Ibs 188 88 Uniden Tabletop Scanner 11 bands of coverage 5 or 15 channels per second scanning speed Features automatic memory search backup priority programmable lockout scan speed control and automatic squelch setting Selectivity 45 dB 25 kHz audio output one watt at 10 THD Takes 117 VAC 60 Hz from an external wall outlet Originally priced at 169 95 Assd BC 175X L 3 Ibs 148 88 100 Channel 11 Band Uniden Mobile scanner Auto search aircraft police marine and emergency bands Fully programmable Fits neatly under dash flip down stand and telescopic antenna included Audio output is 1 5 watts at 1095 THD require 13 8 VDC vehicle battery or AC adapter Save 61 Assd BC 580X LT 5 Ibs 198 88 Oeluxe Uniden Mobile Scanner Save 81 100 channel 12 band mobile scanner Covers 800 MHz band for full 12 channel coverage Weather search priority squelch lockout delay auto and manual band search Mount under uum dash or AC adapter included flip down stand and telescopic antenna Takes 13 8 VDC Assd BC 760X LT 5 Ibs 248 88 CIRCLE NO 115 ON FREE INFORMATION CARD Say You Saw It In Modern Electronics pring Specials from Heath Make life easier E Full featured remote contro center for es
160. lood Alarm detects unwanted Suum water Avert F damage from 2 f leaking water Ea F pipes or basement a wall seepage Three hours to build Needs 9V battery 134 H x 3 amp W x 474 L Kit GD 1701 2 Ibs 12 95 Program your doorbell with a favorite tune Arrange wire leads on one octave a keyboard inside doorbeii to program any tune Includes songbook with 50 college seasonal Christmas and special occasion songs Back door button activates a part tune Volume tone speed and delay adjustable Two evening kit Takes standard 16 VAC 50 60 Hz bell transformer Kit TD 1089 31bs 32 95 Build your own Heathkit draft detector Easily detect heat loss areas Turn it on adjust for silence then move sensor in areas where heating or cooling losses occur Temperature Changes set off beeping alarm and flashing LED Used in temperatures from 59 95F Takes a 9 volt battery not included Kit NE 2112 2 Ibs e 9925252222259 Heathkit Furnace Air Cleaner Works with heating or A C system to reduce the effects of pollen goo 5 dust and cigarette smoke Power supply mounts onto a cold air duct and turns on collecting cell when blower is running 1 collecting cells below directly replace original furnace filter 120VAC also works with GD 2196 2 filters Kit GD 3196 9 tbs 79 95 Accessory filters 4 sizes available each 74 95 9 9 c 9 9 9 9 9 9 9 3
161. losure can be built to complement different decors You can obtain either of two enclosures for your clock from the source given in the Noteat the end of the Parts List if you prefer not to build your own puc u ge a ee M X Nl Ir M SSS About the Circuit The complete schematic diagram of the clock s circuitry including op tional pendulum circuit is shown in Fig 1 which consists of four parts At the upper left in Fig 1 A is the clock s simple power supply Incom ing 117 volts ac is stepped down to 9 volts ac by power transformer T7 and is rectified to pulsating dc by the bridge rectifier made up of diodes D 54 MODERN ELECTRONICS May 1989 through D4 This pulsating dc is fil tered to pure dc by capacitor C7 and is subsequently delivered to the re mainder of the circuitry that makes up the clock At any given time only three LEDs will be on Consequent ly thecircuit draws very little current and power demand is minimal A 60 Hz ac signal is picked off the secondary of T1 and coupled through a Schmitt trigger circuit composed of R1 R2 ICI IC2A and Say You Saw It In Modern Electronics V 2 C b LL Q v us O a TE e Q o Q9 eco ete aa ON 9 u 9 e o9 o5 92 22 lc 5 2 O z 9 TA uu eso zz s oe m N Oo OO 2 S lt Fig 1 Complete schematic diagram of the clock s circuit is shown here i
162. lot inside the system monitor unit allows the Mac intosh SE 30 to support new types of expansion options that were not pre viously available on a compact Mac intosh Already a number of third parties have developed products for the 030 Direct Slot see below Rounding out the features of the basic Macintosh SE 30 is a custom sound chip on the motherboard This chip provides four voice stereo sound capability and compatibility with sound applications Support Picture A variety of products have been and are being readied for expanding the Macintosh SE 30 via the 030 Direct Slot Among the items currently ready or in the works is the internal MacMainframe SE 30 card and communication software from Ava tar Corp that allow the Mac SE 30 to directly connect to IBM 3270 net works Another is Digital Communi cations MacIRMA card that allows the Mac SE 30to function as an IBM 3278 or 3279 terminal for communi Say You Saw It In Modern Electronics cating with an IBM mainframe computer Digidesign s Sound Accelerator a high speed digital audio and digital signal processing DSP card that provides CD quality playback of sounds and performs most sound processing and synthesis functions in real time Epic Technology has has MaxCOMM 2400X a 2 400 1 200 300 baud internal modem On the graphics front are two products of note One is E Machines Big Picture Z21 SE 30 a 21 inch monochrome display system that can
163. lt 1mv lt 3mv lt 5Smv lt 5mv 450 MHz lt 3mv lt 5 mv lt 3mv lt 1mv lt 5mv 850 MHz lt 3 mv lt 20 mv lt 5 mv NA lt 5 mv 1 3 GHz 7 mv 100 mv lt 7mv NA 10 mv 2 2 GHz 30 mv NA 30 mv NA 30 mv ACCURACY ALL HAVE 1 PPM TCXO TIME BASE All counters have 8 digit red 28 LED displays Aluminum cabinet is 3 9 Hx 3 5 Wx t Internal Ni Cad batteries provide 2 5 hour portable operation with continuous operation from AC line charger power supply supplied Model CCB uses a 9 volt alkaline battery One year parts and labor guarantee A full line of probes antennas and accessories is available mm IF OPTOELECTRONICS AF DETECTOR MODEL CCB EAG F tL BC ALE CIRCLE NO 145 ON FREE INFORMATION CARD For SUCCESS in your Vocation or Profession LEARNING is Where It s At You ll need a Learning Environment in your home or office to work on your degree with the college that comes to you GRANTHAM COLLEGE OF ENGINEERING j Low dm M Y Grantham makes your understanding of electronics and compu ters its most important teaching objective You are never rushed or held back you study at your own pace Learn more by self paced home study with Grantham instructors standing by to help you Accredited Now in Our 39th Year A S and B S Degrees 4 Grantham College of Engineering A warded P O Box 539 Los Alamitos CA 90720 Please mail me vour fr
164. mphony WordPerfect and WordStar The board also supports Tecmar s very popular EGA Master 480 800 video mode which has a large base of existing software for 800 by 600 16 color graphics when the 100 Mas ter Graphics option is installed Supplied standard with 512K of vid eo RAM the board can support up to 256 colors in the 800 by 600 mode for applications like PC Paintbrush Plus Publisher s Paintbrush and other pro Video modes that support resolu tions or colors beyond VGA are called extended VGA modes To take advantage of an extended VGA mode you need a special software driver that interfaces the software application to the video mode As a consequence each application that wishes to use an extended VGA mode must have its own driver Until re cently manufacturers of VGA boards have had to write their own applica tions drivers which explains why you generally see extended mode driver support for only the most popular software packages such as Win dows 1 2 3 AutoCAD etc A newly formed committee hopes to rectify thesituation by introducing the Video Electronics Standards As sociation VESA super VGA stan dard VESA boasts 800 by 600 screen resolution in up to 16 colors Though these specifications are not new to VGA boards adoption of the VESA grams that list the Tseng board as a video option The VGA AD s only negative fea ture Is that the displayed image on the video screen flickers a lo
165. mplete Annual Reference Master This valuable new master directory and buyer s guide will serve you day in and day out in searching out new gear comparing new models locating dealers near you and mail order retailers around the country It ll help you buy more wisely with its multi reference concept to help you wend your way through the buying maze COMPLETE PRODUCT INFORMATION It s a Single volume source book of the latest Amateur Radio gear al sectionalized by equipment type for easy reference by the seasoned editorial staff of CQ e Compiete product descriptions e Technical specifications e Retail prices Equipment photographs WHO SWHO IN THE AMATEUR RADIO BUSINESS It S a Buyer s Guide filled with the kind of support information you ve always needed but couldn t easily get Dealer listings state by state including branches names and calls for key per sonnel top lines carried whether or not trade ins are accepted or on site repairs are made and soon BUYING TIPS FROM THE EXPERTS Great articles on the in s and out s of purchasing Amateur equip ment The experts give you the inside scoop on everything from Say You Saw It In Modern Electronics antennas to transceivers to making your first packet contact and lots more ORDER YOUR BUYER S GUIDE TODAY Don t miss the single most valuable buying guide in the Amateur Radio field Send only 3 95 today YES please send my copy of AMATEUR RADIO BUYER S GUIDE 19
166. n Electronics together the fine wires of each con ductor and sparingly tin with solder At the end of the cable from which the shield and tracer wire was clipped slide a l inch length of small diameter heat shrinkable tub ing over and form a small hook in the end of each conductor Next trim the leads of IC13 to a length of about 4 inch and also form small hooks at the ends of the remaining lead lengths Crimp and solder a cable conductor to each lead on IC1i3 At the other end of the cable identify conductors for later use in wiring them Do this ei ther by recording the insulation col ors for each conductor at C13 or by using an ohmmeter to identify the wires and temporarily labeling each with masking tape Slide the tubing over the soldered connections until it is flush with the bottom of 7C 13 s case and shrink the tubing into place Slide a 4 inch length of larger diameter heat shrinkable tubing over the entire cable so it over laps slightly the bottom of the IC s case and shrink it into place Slide a 1 inch length of tubing onto the shield at the other end of the cable and shrink it into place Slide another larger diameter piece of tub ing onto the cable placed so that about 1 inch of the cable conductors extends out the end of the tubing and shrink into place Insert the three cable conductors in the circuit board and solder connec tions to pins 6 7 and 20 of JC 2 us ing Fig 5 and your previous i
167. n cer tain complex mathematical calcula tions to morethan 100 times as fast as its predecessor thus improving the performance of some spreadsheets statistical and numeric based graph ics programs Going beyond the hot proces sor coprocessor combination the company has bestowed upon the m 4 E Say You Saw It In Modern Electronics uuLxum I E m c s LC MCCC REC CE CH EE ee OCDE I EC C RI ca eomm E merce o MM M c e SSS SSS SS Macintosh SE 30 the Apple FDHD Floppy Drive High Density an in ternal 1 4 megabyte floppy disk drive that can read write and format MS DOS OS 2 Macintosh and Ap ple II ProDOS diskettes For maxi mum utility this SuperDrive is said to work with 720 kilobyte and 1 4 megabyte MS DOS and OS 2 diskettes 400 kilobyte 800 kilobyte and 1 4 megabyte Macintosh disk ettes and ProDOS diskettes Convenient access to and transfer of files between the three basically in compatible operating system envi ronments are accomplished with Ap ple File Exchange This is a utility in the Macintosh System Software for use with the FDHD drive This is a great advantage in an office environ ment in which spreadsheets and other data files generated by different com puters must be transported between incompatible machines An expansion slot architecture called the 030 Direct S
168. n four sections A is the basic 1 Hz timing pulse generator ard optional pendulum circuit B is the counter decoder circuitry for the seconds and minutes sec tion C is the circuitry for the discrete LED displays for the seconds and minutes rings and D is the counter dis play circuitry for the hours ring Parts B C and D follow on next two pages Say You Saw It In Modern Electronics May 1989 MODERN ELECTRONICS 55 To vive IC13 Pin 15 IC14A Pin 6 R3 47K To SECONDS LED matrix C3 1Hz from 100pF IC13 P n 12 D11 1N4148 R4 10K a From IC14 Pin 12 To IC9 Pin 13 MINUTES LED matrix NOTE IC2 4001 To IC9C Pin 8 D18 and S3 1N4148 B Ve To seconds counter IC3 minutes counter 1C6 Y Pin numbers iC5 3 2 4 7 10 1 5 6 9 11 IC8 T OI aeu ibo mecum E D5 D12 maaa 0 Aa D Da DP DK a DK DP DK 3 a D6 D13 12 See D7 D14 e Ma d maas DK PK DIO DK DK D D DX DX PX d 4017 8 D8 D15 12 D9 D16 i poses OD Dk DP DK PK DK P DK DX 6 D10 D17 1N4148 J 4 Identical LED matrices for SECONDS and MINUTES display dials LED thru l LED60 LED61 thru LED120 o N o E Se E eg ree ee eet ee J NOTE C IC5 4069 56 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics From IC2D Pin 13 From D18 Cathode S3 and R5 10K LED121 NOTE C9 and IC11 4001 D Semiconductors D1 thru D4 1N4001 silic
169. n t affect the flow of text Secondly because Aldus PageMaker can automatically wrap text around graphics before or after text is placed each publication doesn t have to be start ed by first placing the graphics You can place draw and type any elements at any UNIT MORE 29 00 98 00 HAMLIN MCG 3000 36 CORDED REMO E CONVERTER Ch 3 PANASONIC WIRELESS CONVERTER Our best buy MOVIETIME VR7200A manual tne tune JERROLD 400 COMBO 3690 11900 JERROLD 400 HAND REMOTE CONTROL JERROLD 450 HAND REMOTE CONTROL 2900 1 800 JERROLD SB ADD ON 99 00 63 00 JERROLD SB ADD ON WITH TRIMODE 109 00 7500 M 35 B COMBO UNIT Ch 30utput only 99 00 M 35 B COMBO UNIT WITH VARISYNC 109 00 MINICODE IN 12 39 00 MINICODE N 121 WITH VARIS NC MINICODE VARISYNC WITH A JTO ON OFF 145 00 105 00 ECONOCODE minicode Subst tute 69 00 42 00 0 00 ECONOCODE WITH VARISYNC 79 00 ML D 1200 3 Ch 3 output 99 00 MLD 1200 2 Ch 2 output 9900 time ZENITH SSAVI CABLE READY 119 00 119 00 Finally because a graphic s text wrap INTERFERENCE FILTERS Ch 3onlyi specifications are always attached to EAGLE FD SORSRSMGLER MEN the element PageMaker can reflow text CALL FOR AVAILABILITY around whether drawn or placed each time the graphic is moved cut copied pasted or even re sized When a cut or copied graphic is pasted PageMaker won t reflow text around it until the graphicis drag
170. n the project and measure the amount of time required for the piezo buzzer to sound Measure the delay from the time the POWER switch is thrown to when you hear the alert tone This should be about 28 seconds If the time is more than 1 second off slight ly reposition the knob s pointer with reference to the 15 30 60 minute index and repeat the test When you have obtained a time de lay between 27 and 29 seconds cali bration of the project is complete Check the time delay for the 10 20 40 and 25 50 100 minute index points You should obtain about 19 and 47 seconds respectively When you are satisfied that the set ting of the knob for R5 is reasonably accurate press TEST Switch S2 the piezo buzzer element should sound immediately and continue to sound for as long as the button is held down Using the Pro ject Before using your SunGuard project you should have a fair idea on how much sun exposure your body will tolerate This will depend a lot on skin type In general the fairer your skin the less tolerant you will be to the sun s energy Generally your first day s exposure should be as little as 15 minutes From there you can lengthen your exposure time each day by 5 minutes or so until you de velop a full tan Always check battery condition before you use SunGuard to monitor your sunbathing When you are ready to sunbathe set the desired ex posure time and switch on the project at the start of exposure to the
171. nals 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 Visa M C COD DIGITAL VIDEO STABILIZER ELIMINATES ALL VIDEO COPYGUARDS OF RP Se SD cp eee ee ee ee no sos ruere MI com ToOrder 1 800 445 9285 or 516 568 9850 49 ea 3 tor pan M F 9 6 battery not included SCO Electronics Inc Dept CJ1 581 W Merrick Rd Valley Stream NY 11580 0 ES SS SEE SMES FEATURES Easy to use and a snap to install The best and the most exciting Video Stabilizer in the market State of the art micro chip technology 9610096 automatic no need for any troublesome adjust ments Works on all types of VCRs TVs and Monitors Light weight 8 ounces and Compact 1x3 5x5 Beautifu deluxe gift box Uses a standard 9 Vott battery which will last 1 2 years e Similar units sold elise where for 99 or more UNCONDITIONAL 30 DAYS MONEY BACK GUARANTEE FAST UPS DELIVERY Air Shipping available CIRCLE NO 101 ON FREE INFORMATION CARD Wl EDITORIAL NENNEN Profile of an M E Reader To get a fuller grasp on your professional and avocational background so that we may serve you better we carry out reader research surveys from time to time We just completed our second one the 1989 Modern Electronics Rea
172. ncreases linearly with temperature positive slope The output voltage across the two thermistors de creases linearly as temperature increases negative slope The Fig 7 circuit can be converted into a thermistor whose resistance decreases linearly as temperature increases All that s required is to connect together Outputs and 3 The resistance then ap pears between Outputs 1 3 and 2 The Voltage Divider Thermistors can easily be used in resistor networks like voltage dividers and bridges As shown in Fig 8 a voltage divider consists of two resistors connected in series with each p 5 OE O a 74 MODERNELECTRONICS May 1989 Say You Saw It In Modern Electronics RZ d TETTA Fig 8 The schematic of the basic volt age divider network other The output voltage from the divid er is Vout VRZ RI R2 If the two resistance values are the same out put voltage V out will be exactly half input voltage V The voltage divider is often used to transform the variable resistance of a thermistor into a variable voltage Shown in Fig 9 is a simple thermistor voltage di vider along with the output voltage it produced when the thermistor was warmed by a hot air gun and then cooled with a damp tissue I chose the resistance of R2 to approxi mately match that of tke thermistor at room temperature Therefore the output potential was around 2 volts with the thermistor at ro
173. nd provides a 3 5 1 adjustment range that allows you to manually adjust the desired time of exposure A voltage spike appears across R8 when C suddenly discharges This spike is applied to the base of Q2 to forward bias the transistor into con duction As collector current flows in Q2 a narrow negative pulse whose amplitude is equal to the voltage of battery B is used as a clock for counter 7C2 Integrated circuit C2 is a 14 stage binary ripple counter divider In this project it serves as both a memory device and a clock The counter has all but two of its binary stages avail able at output pins For this applica tion only output pins 6 1 2and 3are of interest These represent clock sig nals that have been divided by 128 4 096 8 192 and 16 384 When power is first applied to the circuit the sudden application of voltage is fed through C3 to the mas ter reset input of C2 at pin 11 to cause the counter to be set to zero At the same time the clock input at pin 10 is being triggered by the pulses that appear at the collector of Q2 as suming PC is intercepting sufficient sunlight intensity to cause the oscilla tor to run Clock pulses cause the counter to advance one count at a Say You Saw It In Modern Electronics Fig 2 Actual size etching cnd drilling guide for project s printed circuit board time at a rate that represents the amount of UV energy striking the so lar cell The unijunction oscilla
174. ne unplug the instru 48 MODERN ELECTRONICS May 1989 PARTS LIST D1 1N4003 or similar silicon rec tifier diode LED1 General purpose light emit ting diode R1 1 500 ohm watt 5 tolerance resistor see text R2 680 ohm 4 watt 5 tolerance resistor 51 Normally open momentary action spst pushbutton switch SCRI CIOG6BI General Electric ECG 5455 or 53597 silicon con ralled rectifier Mise Printed circuit board or perfor ated board see text panel clip or small rubber grommet for mounting LEDI small diameter heat shrink able or plastic tubing small enclo sure and modular cable plug assem bly needed only if project is housed separately from telephone instru ment see text thick double sided foam tape hookup wire solder etc ment from the wall jack and tag the two remaining wires coming from the circuit board assembly accordingly The two wires that remain to be connected go to the telephone line and must be connected in proper po larity as determined above Route these wires from the circuit board as sembly to any two points inside the instrument to which wires from the incoming telephone line connect If these points are soldered solder the free ends of these wires to their re spective points Checkout amp Use Checkout of the hold function is sim ple Start by placing the telephone in strument s handset on hook Then plug the instrument s cord into the wall
175. nformation Applications information for LTN111R 10 LCD module and others Digi Key Cat No AMXDS National Semiconductor 1988 Linear Data Book 2 contains data sheets and applications notes for ADC0804 LM34 LM385 1 2 Digi Key Cat No 9052B ar Jameco Cat No 400042 May 1989 MODERN ELECTRONICS 39 IC15B NOTE IC7 74LS08 IC15 74LSOO Fig 6 Schematic diagram of LCD module and switches that connect to the 8 LTN111R 10 E Microsys to M1 on Apo through AD on pins 7 through 14 Three control lines at pins 4 5 and 6 complete the interface with C2 Pin 3 is a contrast adjust input for the display and connec tions to 5 volts and ground are at pins 2 and 1 respectively To display a character on M1 IC2 writes the address of the position de sired to M1 Alternatively M7 incre ments or decrements the address au tomatically after a character is writ ten to the display C2 next writes the code for the character desired to MI The module then displays the character desired at the position requested Logic gates C I5A ICISB and IC7D generate an enable signal at pin 6 of M1 When Y6 at pin 9 of C3 is low and either RDHI or WRITE is low MI can be read or written to Line Y6 is low when A14 and A15 are high and A13 is low which places M1 at hexa decimal address C000 Address lines A8 and A9 select the operation to be performed when M1 is enabled When A8 and A9 are bo
176. nnect the two sets of locking connectors Tie a knot in the sensor cable to act as a strain relief and route this cable through the rubber grommet in the back panel Do not connect the ribbon cable until pre liminary power supply checks have been made and you are certain that the circuit has been wired correctly Mount 7 S2 and S3 in their respec tive holes on the front panel Checkout Power up the Microsys and use a dc voltmeter or multimeter set to the dc volts function for the presence of 5 volts 0 2 volt between output of IC11 and circuit ground Connect the meter s common lead to any conveni ent circuit ground point in the circuit and use the hot lead to probe the circuit for this measurement Also measure for 5 volts from pin 2 to Program 6 Write Temperature to Screen REM Program 6 write temperature to screen DO XBY 0E000H 255 ADCzXBY E880H TEMPsADC 2 47 109 255 REM write to adc to start conversion REM read adc output REM calculate temperature PRINT The temperature is TEMP degrees Fahrenheit WHILE 1 1 END Program 7 Write Temperature to LCD Module REM Program 7 write to LCD module XBY C H l XBY C H 38H_ XBY C H CH XBY C H 6 XBY 0CO00H 80H FOR Il TO 4 XBY 9C200H 2AH NEXT I XBY C2 H ASC T XBY 9C200H ASC E XBY C2 H ASC M XBY C209H ASC P XBY 0CO90H 0C H XBY 0C2090H ASC W
177. om temperature This standby voltage can be increased by in creasing the resistance of R2 Converse ly it can be decreased by decreasing the value of this resistor The voltage divider s ability to provide an adjustable standby voltage makes pos sible many applications in which a com ponent or circuit is triggered by a change in voltage caused by a change in tempera ture We ll look at some simple circuits to do this later First it s important that we examine a special form of voltage divider The Wheatstone Bridge A Wheatstone bridge is composed of two voltage divid ers connected in parallel with each other as illustrated in Fig 10 When the voltage from the first divider Vgl equals that Say You Saw It In Modern Electronics ALR WET TiS u Gun 1 4 4 SECONDS Fig 9 Plot of a thermistor voltage divid er s output from the second divider Vout2 the bridge is said to be balanced and R1 R3 R2 R4 It is important to monitor the voltage with a high impedance meter otherwise the meter s internal resistance will affect operation of the bridge A common use of the Wheatstone bridge is the measurement of an un known resistance Referring to Fig 10 assume that the values of R7 and R2 are accurately known that potentiometer R4 s scale is accurately calibrated and that R3 is an unknown resistance After R3 is connected into the bridge R4 is ad justed until the bridge is balanced The
178. on position Use an ordinary dc voltmeter or multimeter set to the dc volts function to perform voltage checks before installing the ICs in their sockets This meter should have an input resistance of not less than megohm Clip the meter s common probe to the negative lead of electrolytic capacitor C2 Then touch the meter s positive probe to pin 14 of the C socket and pin 16 of the C2 socket In both cases you should obtain a meter reading of approximately 9 volts If not power down the circuit and carefully check your work for wiring errors components installed in the wrong locations and or wrong orientations etc Do not proceed un til you have rectified the problem Once you are certain that every thing is okay install the ICs in their respective sockets Make you proper ly orient each and that no pins over hang the sockets or fold under be tween the ICs and sockets Now pro ceed to calibrating the project SunGuard is easily calibrated with the aid of the meter you used to per form checkout a watch or clock with a sweep second hand or a seconds counting function and a regulated dc power supply that is capable of supplying 5 5 volts The last is a con venience but not a necessity The first part of the circuit to be calibrated is the solar cell and opera tional amplifier C7 For calibration of this circuit you must have clear sky conditions and the sun at full brightness Continued on page 8
179. on rectifier diode DS thru D22 1N4148 or similar switching diode LEDI thru LEDI42 Jumbo red light emitting diode IC1 CD4082 dual 4 input CMOS AND gate IC2 CD4001 quad 2 input NOR gate IC3 1C4 IC6 1C7 1C10 1C12 IC13 CD4017 CMOS decade counter ICS IC8 CD4069 CMOS hex inverter buffer IC9 ICI11 IC15 IC16 CD4001 quad 2 input CMOS NOR gate ICI4 CD4013 dual CMOS D flip flop IC2B Emerging from the output of this circuit at pin 4 of C2B is a square waveform that reliably triggers the initial counter in the clock Shown immediately below the power supply section in Fig 1 A is l Hz divider pendulum circuitry Three basic functions are served by the this circuit it divides the line fre quency down from the initial 60 Hz to Hz it provides fast set pulses that allow you to quickly set the time Say You Saw It In Modern Electronics 1N4148 D19 1N4148 PARTS LIST Capacitors C1 250 y4F 35 volt electrolytic C2 100 pF Mylar or ceramic disc Resistors watt 5 tolerance R1 18 000 ohms R2 R3 R6 47 000 ohms R4 R5 10 000 ohms Miscellaneous S1 S2 S3 Momentary action spst push button switch T1 9 volt 30 to 40 mA power trans former see text Main and pendulum printed circuit boards sockets or Molex Solder cons for ICs ribbon cable hard ware hookup wire solder etc in the clock s display and it displays a LED pendulum that appears to swing in an arc
180. onditions you simply switch off the tape player Now there is no voltage dropped across RECTI and Ql cuts off This causes K to deenergize and restore the circuits between the radio s out put s and speaker s Construction There is nothing critical about com ponent layout or conductor routing in this project Therefore you can use just about any traditional wiring technique to assemble the Smart Car Relay For example if you wish you can design and fabricate a printed circuit board on which to wire the project Alternatively you can use perforated board and suitable solder ing or Wire Wrap hardware Begin assembly on your chosen cir cuit board medium by installing the bridge rectifier assembly or individ ual diodes if you have chosen to use these instead of the rectifier assem bly Then install transistor Q7 di ode D and resistor R Make sure the diode is properly oriented and that the transistor is properly based before soldering any connections these make with the rest of the circuit Strip of insulation from both ends of as many 12 inch long stranded hookup wires as needed for the relay contact lugs and the three electrical system connections Choose wire weight according to the current that will be drawn by the device being May 1989 MODERN ELECTRONICS 51 12V fuse block accessory 12V INPUT COMMON Smart Car Relay NORMALLY CLOSED 12V audio un
181. one end of two of these 26 MODERN ELECTRONICS May 1989 wires into the holes labeled R5 and solder into place Plug one end of another wire into the hole labeled S3w between Q2 and R13 onthe board and solder this into place Now depending on whether you are using a single range or three ranges plug three wires or one wire into the holes labeled 3 2 and or the appropriate hole for the single range and solder into place Plug one end of another pair of wires into the holes labeled s2 and solder them into place Then do the same for the remaining two wires and the holes labeled S1 and B1 If you omit S3 temporarily solder a jumper wire between the hole la beled S3W and pin 6 of the C2 socket to make a quick calibration of your project Then once R5 is calibrated permanently wire R 3 to the desired output terminal of C2 in accordance with the selected time delay listed in the Time Delay Range chart When you have completed wiring of the circuit board assembly care fully examine both sides of it to make sure all components are installed in the proper locations and orienta tions Check the solder side of the board keeping an eye out for missed connections poor soldering and sol der bridges the latter especially be tween the closely spaced IC socket pin pads Solder any connections missed reflow the solder on any point that appears to be suspicious and use desoldering braid or a vac uum type desoldering tool
182. ongest frequency of the moment In practical terms there may be a 100 kW transmitter a few blocks away and a 1 watt transmitter 10 feet away The counter will see the 1 watt unit first because there s an inverse square relationship between signal strength and distance As a result of the foregoing the counter can be used to measure an unknown signal near it without the operator having to tune in the fre quency This opens new vistas for the MEME qr ro oo au N May 1989 MODERN ELECTRONICS 35 Counter Connection Methods Direct Cable Directly connecting a frequency counter to an oscilloscope s vertical channel output jack at the rear verifies a 1 kHz signal Off The Air A counter with a telescoping whip antenna Direct Probe A 1 x general purpose direct probe is used measures the frequency generated by a cordless telephone to connect the counter to a crystal oscillator circuit 36 MODERN ELECTRONICS May 1989 Say You Saw lt In Modern Electronics 0 AA s H JJ A w A A U Y u siset Typical Off The Air Count Distance From Transmitter With 2210 Frequency Counter amp Telescoping Whip Antenna setae NOCET TM LCE Sey 10 owner of a frequency counter espe cially if it s a battery powered por table one like the project is An accompanying frequency chart illustrat
183. ons of all units in the International System or S I as it s abbreviated are reported to be made in double precision real arithme tic and the program displays single pre cision numbers It s very easy to use especially when automatically loaded as a resident mem ory program Terminate and Stay Resi dent or TSR that can be activated within another program by pressing Alt F10 keys simultaneously You can also oper ate the program as a stand alone one though it won t operate when another program runs When the program s main menu is acti vated fivecommand words are displayed across the screen top that relate to Help String Search for all unit menus Op tions Finding a String in a current menu and Exiting to DOS The middle of the menu lists over 80 unit classes Area Electric Capacitance Electric Flux Den sity Frequency Noise Level Induc tance etc Using a cursor control key moves the cursor to theunit type line that the user wants to do the conversions in Length for example would be the unit chosen if you wanted to convert a frac tion of an inch to millimeters Pressing Enter displays two side by side boxes that contain identical lists of units in the class selected The left hand box contains the From units while the right hand box listing represents the To units Left Arrow and Right Ar Say You Saw It In Modern Electronics row keys are used to select which one you work in while Up Ar
184. ontinue to grow Heath Zenith s latest voice is a simulation of a barking dog Part of the company s Barking Dog Security Alarm System with a suggested retail price of only 59 95 it s actually an infrared motion detector housed in a weather tight case The unit employs Pulse Count Technology to prevent small animals from falsely triggering the alarm The dog bark can be switched to a pleasant sounding chime too NYNEX Mobile Communications has introduced an exciting new cellular telephone that s activated by the operator s voice It can be set up to automatically dial up to 20 pre programmed phone numbers at just the sound of a voice Additionally its new NYNEX Model 832SR allows users to leave a 15 second personal voice message to incoming callers when away from the vehicle and has an RJ11 jack output for use with portable laptop computers and modems To use voice dialing the operator simply depresses any key on the phone and says the name of the person to be called The 832SR confirms the name and then automatically dials the number Moreover it has the ability to recognize a second voice so that if more than one person uses the car both can employ voice dialing with each programming up to 10 numbers Now that s what we call hands free and a lot safer to do while driving AUDIO MUSEUM An Audio Museum tour will be a special attraction of a San Francisco area high end hi fi show April 21 23 at the Dunfey Hotel San Mateo CA
185. or owned very small companies gained 6 7 now totaling 30 6 The group ranging from 250 to 999 lost 2 6 while 1 000 and over lost 3 2 together they now total 34 Remaining groups 50 to 249 and 10 to 49 employees account for 35 4 Length of time working in the electron ics or computer fields are telling indica tors of a reader s on the job knowledge as well as a rough indicator of age This is the way we posed our question rather than in age brackets Six choices were of fered starting with None 15 4 chose this category the only one that s difficult to pinpoint by age since a re spondent could be a young student but could also be an older person who is con sidering a career change The next choice was to 5 years experi ence to which 20 4 checked off Age here probably ranges from 21 to 27 years This was followed by 24 9 for 6 to 15 years experience which likely translates to 26 to 37 years old For 16to 25 years ex perience which is probably a 36 to 47 year old range 20 2 were counted Next 10 5 were in the 26 to 35 years ex perience range probably aged 46 to 57 while another 8 8 had over 35 years ex perience and are over 55 years old The median years of work experience should then be about 11 years while age should be around 31 or 32 years or so Comparing the foregoing figures to 1986 Study results indicates that the Modern Electronics reader s average age now is about five years yo
186. or most desktop publishing CAD CAM and serious graphics applications IBM may have created the VGA standard for its PS 2 series of com puters but the good news is that you don t need a PS 2 to reap its bene fits There are currently dozens of VGA compatible adapters available for the PC and PC clones in the mar ketplace They range in price from a low of about 400 up to and beyond 1 000 depending on speed and op tions Many of these products offer features not found in the original IBM VGA And thanks to stiff com petition prices for VGA hardware are only slightly more expensive than those for EGA making the former with all its advantages the better in vestment for the future I t wasn t too long ago that PC What VGA Offers Unlike the IBM video modes that came before it VGA offers a pot pourri of possibilities In just the IBM VGA mode alone you have up VGA Modes Mode Mode Colors Box Size Format Comment Standard Modes 0 1 Text 16 8x8 40 x 25 CGA 2 3 Text 16 8x8 80 x 25 CGA 0 1 Text 16 8 x 14 40 x 25 EGA 2 3 Text 16 8 x 14 80 x 25 EGA 0 1 Text 16 9 x 16 40 x 25 VGA 2 3 Text 16 9 x 16 80 x 25 VGA 1 4 5 Graphics 4 8x8 320 x 200 CGA 2 6 Graphics 2 8x8 640 x 200 CGA 7 Text mono 9 x 14 80 x 25 MDA 7 Text mono 9 x 16 80 x 25 VGA D Graphics 16 8x8 320 x 200 EGA E Graphics 16 8x8 640 x 200 EGA F Graphics mono 8 x 14 640 x 350 EGA 10 Graphics 16 8 x 14 640 x 350 EGA 3 11 Graphics 2 8 x 16
187. ount a switch and light emitting diode on it Therefore make sure you do this only toaninstrument you own not one you are leasing If you do not own your telephone in strument s but would still like to use the hold circuit described in the text you can do so by housing the circuit in a separate enclosure In this event con nect the project to the telephone line via a standard cable terminated in a modu lar plug Keep in mind that this project con nects directly across the telephone line If it causes problems on the line the telephone company hastheright to tem porarily discontinue service to you In thisevent you will be notified and given the opportunity to correct the problem However it is always better to make sure no problem exists from the start for LEDI plug one end of the black and the remaining red insulated wires into the cathode and anode holes respectively and solder both connections Loosely twist together these two wires Plug one end of the remaining two wires into the two SI holes and solder them into place Select a location inside the tele phone instrument to mount the cir cuit board assembly where it will not physically or electrically interfere with any portion of the instrument If necessary carefully trim away the tab on the SCR there will be no de gradation in circuit performance if you do this If there is no room in side the instrument for the circuit board assembly house
188. our terminal power up the Microsys and press the SPACE bar at the terminal If you don t see the READY prompt power down and locate and fix the problem before continuing Re examine the added wiring on the Microsys Be sure your terminal is configured properly as described last month When you do obtain the READY prompt ycu can begin measuring temperature The listing given in Program 6 reads the output of IC12 converts it to a temperature and displays the result on the termi nal s videc display screen Key in Program 6 at your terminal and fol low this bv typing RUN and a car riage return ENTER key to run it The terminal screen will now display any measurements in degrees Fahr enheit taken by the sensor Program 6 uses the special opera tor XBY in MCS BASIC 52 to read and write to external memory Line 20 writes the value 255 to C 2 which is located at hex address E000 Writing to JC 2 causes this IC to Say You Saw It In Modern Electronics REM Program 8 switch test PRINT CONTROL C to quit DO X PORT1 YsX 4 INT X 4 REM read por 1 REM calculate bit 1 bit 2 of port 1 IF Y 2 THEN PRINT Bit of port 1s S2 pressed IF Y l THEN PRINT Bit 1 of port 120 S3 pressed WHILE 1 1 END begin converting its analog input to a digital word The actual value writ ten to the ADC is unimportant any write command serves the purpose Line 30 reads the byte at ADO through AD of
189. ow NRI s breakthrough training can put you at the heart of the robotics revolution Send today for NRI s big 100 page full color catalog that gives you all the details about NRI s exciting new training in Robotics Technology plus training in computer electronics SEND ae For Career courses approved under Gi Bill McGraw Hill Continuing Education Center 4401 Connecticut Avenue NW Washington DC 20008 check for details Industrial Electronics Radio Communications cu ECK ONE FREE CATALOG ONLY O Computer Electronics Small Engine Repair Electrician TV Video Audio Servicing Basic Electronics Lo xksrmithing Electronic Music Technology Bookkeeping and Accounting Cellular Telephone O Security Electronics Building Construction Paraiegal O Electronic Circuit Design Air Conditioning Heating amp Refryeration Name Please print Age Autamotive Servicing Street O Digital Electronics Servicing City State Zip We ll give you tomorrow _ _ 9000 OEE lr 80808080 ET 808080 ES UR W NEW PRODUCTS ERR 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 Dual Display DMM John Fluke Mfg Co Inc has a new multimeter that features a multi function dual display so that the in strument can make more measure ments from a single connection than i
190. play for readings up to 1999 audible continuity checker and diode test Overload protected on all ranges new transistor hFE test Assd SM 2310 1 Ib Now only 24 95 Connector adapter kit Make 108 different Coaxial connector adapters with gold plated pins and Teflon insulation Kit contains male and female N BNC UHF SMA TNC and mini UHF connectors Special in NI between fittings allow you to assemble i your own adapters in seconds Assd HCA 3000 2 Ibs 69 95 Coax adapter cables Solve frustrating s coax connection problems with this convenient adapter cable assortment Twenty cables in all help you make almost any connection Two handy storage racks keep your cables neatly organized 50 ohm impedance Assd TP1 5000 5 ibs Now 49 95 Unbeatable Scanner Prices Uniden 10 Channel 10 Band Handheld Scanner Save 31 Superportable programmable direct channel access channel lockout keyboard lock switch prevents accidental reprogramming 55 dB 25kHz selectivity audio output 300 milliwatts maximum Receive 29 to 512 MHz with a 15 channel per second scan speed Requires 5 AA not included or rechargeable NiCd batteries Assd BC 55X LT 11b 108 88 100 Channel 11 Band Uniden Handheld scanner Reduced 41 100 programmable channels 10 scanning banks 11 bands of coverage Automatic and manual search weather search 10 priority channels squelch
191. possible to the TI SECONDARY holes in the upper left corner of the board Mount the trans former in place using two No 5 x inch wood screws If you are using a basic power transformer mount a two lug ter minal strip near its primary leads and crimp but do not solder the primary leads to its lugs Route the ac line cord through a hole you drill in the enclosure s rear panel and tie a strain relieving knot in it about 5 inches from the free end inside the enclosure Tightly twist together the fine wires in each conductor and tin with solder Solder the conductors to the lugs of the terminal strip Plug the transformer s secondary leads into the TI SECONDARY holes in the main board and solder into place Set the main board into place in side the enclosure but do not fasten it down Now plug the conductors at the free end of the ribbon cable into the holes in the pendulum board again from the rear of the board labeled A through H and TO MAIN BOARD and solder into place Match letter desig nations between boards Set this board in place inside the enclosure without fastening it down Accurately locate and drill the holes for the pushbuttons on the three pendulum board switches through the fronting plastic sheet Checkout amp Use With the ICs still not installed in their respective sockets plug the clock s line cord into an ac receptacle Clip the common lead of adc voltmeter or multimeter set to the dc volts f
192. quires just enough desktop space to set it in place It per mits use of an Alternate Cursor switch for CAD CAM applications and has a Drag function that gives the user the ability to hold down a button and roll the ball at the same time In addition to the universal di rection ball six general purpose pushbutton switches are available Separate versions with DB 9 and DB 25 connectors are available Supplied with software drivers for the Microsoft Mouse and Mouse Sys tems Mouse Trackball Plus also fea tures MenuKey for programs that do not normally support a mouse Menu support is provided for Lotus 1 2 3 and WordPerfect The software has the ability to change the sensitivity of the device while in a program Re sponse can be customized by down loading more than 20 commands and arrow key emulation is built in 99 HAM RADIO I FUN It s even more fun for begin ners now that they can oper ate voice and link computers just as soon as they obtain their Novice class license You can talk to hams all over the world when conditions per mit then switch to a repeater for local coverage perhaps using atransceiver in your car or handheld unit Your passport to ham radio adventure is TUNE IN THE WORLD WITH HAM RADIO The book tells what you need to know in order to pass your Novice exam Two cassettes teach the code quickly and easily Enclosed is my check or money order for 15 00 or charge my VISA Mas
193. r types of sounds though Top 100 and Volume 2 are not precisely descriptive of sounds named LIQUID and JOCKO There are two ways to select a particular patch You can enter the three digit patch number with the right hand keypad then press the enter key or you can use a feature Oberheim provides called Bank lock This lets you enter a bank number then lock it temporarily into the Matrix 1000 Then to select a sound all you have to do is key in two digits and hit en ter This is convenient if you are going to be assigning several patches from the same bank To turn off or unlock the bank just press the Bank Lock switch again Patches are changed from a sequencer or computer running a sequencer program by executing a MIDI Patch Change command Exactly how this is accom plished varies from package to package but most sequencer packages have this capability A truly creative and or professional musician will appreciate many of the ef fects and sounds available I ve only got ten through about 20 of them so far Out of these about 50 sound like something I might eventually use about 78 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electronics 30 are a little too far out for my partic ular taste and the remaining 20 sound very similar to something in the first 50 to my undiscriminating ear Still if the averages hold out 500 useful sounds and instruments are nothing to sneer
194. rammable unijunction transistor Q1 and its associated components which make up arelaxation oscillator circuit are used to convert the volt age generated by C into a time de pendent function Capacitor C is charged through R5 and R6 by the voltage generated at the pin 14 output of JC B The rate at which C7 charges is proportional to the voltage delivered by JC B and the total resistance of R5 plus R6 P1 Piezoelectric sound element Radio Shack Cat No 273 065 or similar PC1 Silicon solar cell Radio Shack Cat No 276 124 or similar 0 3 ampere solar cell S1 Spst slide or toggle switch S2 Spst normally open pushbutton switch S3 Single pole 3 or 4 position switch optional see text Printed circuit board or perforated board with holes on 0 1 inch centers and suitable soldering or Wire Wrap hardware see text clear plastic en closure see text DIP sockets for IC1 and IC2 snap connector and holder for Bl pointer type control knob 2 silicone adhesive or fast setting epoxy cement see text dou ble sided thick foam tape machine hardware hookup wire solder etc Note The following items are available from A Caristi 69 White Pond Road Wald wick NJ 07463 Ready to wire pc board 9 95 LM324 2 CD4020BE 3 50 2N6027 3 0 2 ohm wire wound resis tor 1 50 set of three metal film preci sion resistors 1 50 Add 2 00 postage handling New Jersey residents please add state sales
195. rate sheet Continued on page 90 Interior view of author s prototype built on perforated board and housed inside a standard metal utility box May 1989 MODERN ELECTRONICS 53 Project An Analog Display Digital Clock Combines appeal of the round dial of traditional analog movements with high technology digital driving circuitry By James Marshino he clock desscribed here com i bines a timepiece that has the appeal of a traditional ana log display with the high tech per formance of a digital movement This clock uses concentric circles of 60 seconds LEDs 60 minutes LEDs and 12 hours LEDs instead of the tra ditional hands found on analog clocks to point to the time of day You can build either of two ver sions of the clock a basic version that consists of the simple hours minutes seconds display and a more sophisticated version that adds to this an optional pendulum that consists of 10 LEDs arranged in an arc Both versions use the same dis play and movement You can house your clock in any of a number of different enclosures ranging from traditional clock styles to a contemporary shallow square depending upon your woodworking skills and taste A shallow square en closure that hangs on a wall is the easiest way to go but if you arereally ambitious and are a skillful wood worker a wall hung Regulator case or even a floor standing long case grandfather enc
196. re Cut the cable to length Then separate the conduc tors at one end into two bundles of four conductors for a distance of 6 inches Then separate all conductors at both ends a distance of 1 inch and strip from each inch of insulation Twist together the fine wires in each conductor and tin with solder Flip over the main board and plug the conductors at the end of the cable where separation is only 1 inch in all cases into the holes labeled A through H and TO PENDULUM BOARD Solder them into place The other end of this cable will be connected to the pendu lum board after you install the main board it in its enclosure You can fabricate your own enclo sure for the clock or purchase one ready for installation of the electron ics package from the source given in the Note at the end of the Parts List A build it yourself enclosure can be made from any materials you wish including lumber painted or veneer finished particle board or even all acrylic plastic depending on your tastes and shop skills Whichever way you go though use a transpar ent red or gray smoked plastic filter in front of both the clock face and pendulum to enhance contrast and camouflage the board unless of course you want the high tech look of the circuitry showing through clear plastic Set the main board in place inside the enclosure orienting it as shown in Fig 5 Determine where to mount the power transformer It should be located as close as
197. ricoe Agparumente 9 eec gi veuen 0 WO te 6 919 mw XO tota pane l4 gi wee j N4 sow pe ient of wei oot m4 tote z each of swum PODU wo 2 OX E oo aD W Wet Rene Aseortmente ate sh gt a T0 men sedmi oeio wea armi n tte Dep Aey catalog 068 iow pao 6 METAL OXIDE FILM RESISTORS Rentatte in 1 amp 2 Wen tow To Order T tig acy standard euer salve lis 1 UK amd adel a WT Tor 1 gl or add W7 o emo 1 52 WT for BK Q T eni tue a Pe Dep Key pert cunt fci wo x Pen hee 1 Wert tta Cep Yon _ qecpo 2L 9 0 Wo v 4000 or m rad Wart P4anz 00 i to A n 00 e ga x9 7 ae Pane 00 h n 4008 00 pa 94007 0 gt m PA lt 0 e m Wor ew nemmo Acterian to PAR E n amp S mew Beech of wees 0 479 19 580 na o 5h 300 570 3 76 an 25b toe peres T 4 4 OM agn beach of onem Cio 566 m Bata am z t es o Tb top pec Paa 00 o Lad Paral TMO s AGW Basch of valusa BRE io 1 OM amm a Z5 ww s Paras D0 0 P4 14A 0D c o 75 Wen Rinit eumctrmem te Patan mon r WAS Seach of quam 0 499 16 OD we rate 10000 ue ues proces Machines 3000 s AE back M emus EZU a 5A am ML IXWD p Pub v m P4150 IED p MEME Beach o verum Jc Q mp OS m e ux 0 vesti oy Dap zo IR 1 Pernice verti preci sp gry the 4 prie Qo thr otal a kc th CN TL TEET TTT EG duu tesemsuysusway 3i 1 s RON Ce Sees leees Ba
198. rns on when source voltage reaches instan taneous value of 30 volts C gate current waveform produced by C6 discharging through DI your controller design is 10 000 ohms That is if yo use 10 000 ohms for R11 R R 2 s value should be 5 000 ohms R 2 R 3 s should be 2 500 ohms R 4 and R14 s should 5e 1 250 ohms R 8 As you can see in the upper right corner of the schematic this circuit receives its 8 volt dc power from a simple voltage regulator circuit that is fed from a common 9 volt dc plug in power supply If you build the cir cuit from scratch you might want to incorporate the dc power supply in the basic design using a 12 6 volt 150 milliampere transformer bridge rectifier assembly and large value fil ter capacitor in place of the plug in power supply Bear in mind when assembling the circuit that all unused segments of the LCD004 display module must be tied to common pin 1 of the assem bly Also when putting the circuit in to operation adjust the setting of R11 to a value of 250 000 ohms ME Say You Saw It In Modern Electronics Test Equipment Photo credits Tracey Trumbull By Bill Owen ast month we presented plans to build a compact portable frequency counter that spans audio through microwave frequen cies Making it count as with any other frequency counter is simply a matter of understanding how to use it properly To use such an instrument effec tively
199. row and Down Ar row keys move a highlighted bar to any unit chosen for conversion The box you work in assumes a double line box and is highlighted At the bottom of the From box is an in put area where up to 14 numbers may be typed Entering the number to be con verted the conversion to the unit that the highlight bar of the To box is on is auto matically displayed below the Toor right hand box Moving the right hand s high light bar to another unit that s listed changes the number below the box to a correct one for the new unit chosen The number is automatically registered for the input until it s changed At the right frame line of each box is a 9 sign that moves up and down to sig nify what percentage of the entire list that the highlight bar is on With a very long list of units such as in the Length class this information can be mildly comforting The Options Menu allows you to re move unit types and specific units that you do not need which will speed going through a list for a selection You re giv en the choice of saving or not saving such changes when you try to exit the pro gram If all the units are deactivated then the whole class will be deactivated Conclusions I found the modestly priced S I Plus pro gram to be very useful in editing and writ ing technical manuscripts The only ini tial problem that one may face is deter mining which heading should be chosen for some units but a reading
200. rus E SES SC RSE SES EE oe PANASONIC V SERIES Temi e lotsaren Fe F amro e SERVICE CHARGES 9 0 00 024 90 Add 03 0 25 00 end Up No Charge 100 00 249 99 WHEN ORDERING BY PHONE CAL 1 000 344 4539 AK cait 210681 6674 6 MAM SEND YOUR ORDER TO DIGI KEY P O Bos 677 Thiet Arve Fatis MM 56701 250 00 499 99 DIG MEV GUARANTEE Any dn 80 toy pl at yr gt PRICES SUBJECT TO CHANGE WITHOUT NOTICE CIRCLE 36 ON FREE INFORMATION CARD 500 00 999 99 T TW i i 1000 amp Up 800 344 4539 Telex 62827914 FAX 218 681 3380 TWX 9103508982 DIGI KEY CORP PANASONIC V SERIES Domehss Mipi ET D Paa 2 eas Press i st BECESsmIsSEzE vtm PCCaC 393828 ee ES uw d QUART CRYSTALS i F PANASONIC OPTOELECTRONICS Purg VOLUME DISCOUNT 0 00 99 99 NEY Less 10 he a 325 pya ttes ER yiuiid 32385242844 ROOM SURVEILLANCE TELEPHONE e This iS a normal functioning telephone EXCEPT it has a secret built in room monitor ius d Only YOU can call and monitor all room conversations using a Secret code and never be detected 175 00 6 month Warranty Phone Tap Catalog 3 00 LISTEN ELECTRONICS 603 Elgin Muskogee OK 74401 1 800 633 TAPS FINALLY An interesting and worth while project This EASY TO BUILD circuit lets you use any regular TY set as e a simple OSCILLOSCOPE DETAILED PLANS
201. ry in place Do not drill mounting holes for the cir cuit board assembly it will be mounted with strips of thick double sided foam tape Mount the piezo buzzer element inside the enclosure securing it in place with a daub of silicone adhesive or fast setting epoxy cement There is no need nor is it recommended for you to drill holes in the enclosure to allow the sound to escape since the intensity of the alerting tone is suffi cient to be heard through the enclo sure s walls When mounting the components on and inside the 2nclo sure do not forget to allow room for the battery Shown in Fig 4 is actual size art work you can cement on the cutside of the enclosure for use in calibrating R5 Make a photocopy of this art work instead of cutting up the page if you wish If you needa slightly small er or larger illustration many photo copy machines permit reduction and enlargement of the original After cementing the artwork to the enclo sure spray over it two or three light coats of clear acrylic to protect it from wear and abrasion Allow each coat to dry before spraying on the next Place suitable pointer type control knobs on the shafts of the po tentiometer and multiple position switch S3 Checkout amp Calibration If you installed the integrated circuits in their sockets during assembly carefully remove and set them aside Snap a fresh 9 volt battery into its connector and set POWER switch S7 to its
202. s automatic operation sensing and switching for electrical devices in an automobile By Dennis Eichenberg 54 An Analog Display Digital Clock Combines the appeal of the round dial of traditional analog movements with high tech digital driving circuitry By James Marshino MPH LEE ie 68 Apple s High Performance Macintosh SE 30 d wea ATTRITI TETTEIT nl ATIT FT Desktop computer operates at up to four times as fast as the Mac SE and provides MS DOS and OS 2 disk compatibility TUTTE ih COLUMNS 72 Electronics Notebook Experimenting With Thermistors By Forrest M Mims Ill 78 PC Capers A Potpourri of MIDI Computer Hardware and Software By Ted Needleman 83 Software Focus S 1 Plus Converting Celsius to Fahrenheit etc By Art Salsberg DEPARTMENTS 6 Editorial Profile of an M E Reader By Art Salsberg 8 Modern Electronics News 9 Letters 14 New Products 71 Books amp Literature 90 Advertisers Index 4 MODERNELECTRONICS May 1989 EDITORIAL STAFF Art Salsberg Editor in Chief Alexander W Burawa Managing Editor Dorothy Kehrwieder Production Manager Melissa Kehrwieder Production Elizabeth Ryan Art Director Barbara Scully Artist Pat Le Blanc Florence V Martin Phototypographers Hal Keith Illustrator Bruce Morgan Photographer Forrest Mims III Ted Needleman Curt Phillips Contributing Editors BUSINESS STAFF Richard A Ross Publisher Art Salsberg Associate P
203. s in the picture tube has a single input that connects to a voltage driver When the input volt ageis low the gun is off Conversely when the input voltage is high the gun is fully on Any voltage between these two extremes represents a dif ferent intensity of that color and this intensity is continuously variable All colors of the rainbow can be made using just three inputs For example to change from white to pink the only thing that need be done is to in crease the input voltage to the red gun Theoretically there is no limit to the number of shades you can dis play on an analog monitor Several VGA boards support both TTL and analog monitors This dual support permits you to use an exist ing CGA or EGA monitor with the VGA adapter This is a handy feature for those people who can t afford both a VGA board and VGA moni Sigma VGA H 399 Sigma Designs 46501 Landing Pkwy Fremont CA 94538 415 770 0100 SotaVGA 16 445 Sota Technology Inc 657 N Pastoria Ave Sunnyvale CA 94086 408 245 3366 STB VGA Extra EM 399 STB Systems Inc P O Box 850957 Richardson TX 75085 214 234 8750 Tecmar VGA AD 695 Tecmar Inc 6225 Cochran Rd Solon OH 44139 216 349 0600 Video Seven FastWrite VGA 599 Video Seven V RAM VGA 799 Video Seven Inc 46335 Landing Pkwy Fremont CA 94538 415 656 7800 tor at the same time but it does pre vent them from displaying VGA or extended mode images until an
204. s possible with a traditional DMM The Fluke 25 s dual five decade vac uum fluorescent displays provide 100 000 counts but additional reso lutions of 30 0000 and 3 000 counts can be user selected The DMM also features a built in RS 232 serial in terface for PC instrumentation ap plications and an optional IEEE 488 interface is available i Functions are included for toler ance testing using a hi lo pass scheme counting frequency up to MHz counting decibels with 21 ref erence impedances indicating audio power and testing diode junctions and continuity Other features in clude true rms dc measurements in both voltage and current modes MIN MAX relative reference Touch Hold and autoranging Man ual or closed case calibration are possible over either the RS 232 or op tional IEEE 488 interface The instrument has a basic six month Vdc specification of 0 02 Basic one year accuracy specifica tions include 0 025 on dc volts and 0 2 on ac volts 0 05 on dc cur rent and 0 5 on ac current 0 05 on resistance and 0 05 on frequen cy counting Using the RS 232 interface mea surement data can be filed and ma nipulated by a PC printed or trans mitted by modem Optional Quick Start 45 software permits automated communication and filing of mea surements with the meter and an IBM PC or compatible computer via the RS 232 port Available options in clude a battery soft carrying case and rac
205. se either a 10x scope probe or a large value series resistor The largest possible resistor value should be used that will still allow a measurement to be made Typical values range from from 100K to 100 megohms You might also use a mul ti turn loop of wire sometimes called a sniffer asa pickup that s placed close to the crystal if the device radi ates sufficient energy This method should have minimal influence on the oscillator s frequency since the cir cuit isn t loaded Note that only the relatively low frequency range A should be used for direct measurements Sig nals of higher frequency oscillators have to be indirectly counted using the sniffer device to avoid having the counter s 50 ohm input impedance stop the circuit s oscillation Indirect Connection Methods The sniffer device mentioned ear lier is an example of an indirect con nection method of coupling a counter to whatever you re counting You can also use a short whip anten na connected to the counter s input to pick up a radiated signal from say a transmitter if you re close enough and the output signal is strong enough This is a popular way to use a frequency counter greatly expanding its applications A frequency counter isn t like a ra dio of course Whereas a radio is de signed to be tuned to selected fre quencies a counter is a broad band device that responds to the dominant str
206. sional listening devices of course Our chart shows that 10 feet is about maximum dis tance for the mike However the as sociated threat from this type of snooping is generally a lot less peri lous than that of the pro Bear in mind that if you re walking around a room with a powered up counter with antenna attached and there is no strong r f signal in the area a constantly changing counter display will likely be generated Don t try to interpret such readings which are meaningless Such self os cillation from internal r f amplifier antenna interaction is due to a count er having good sensitivity It s merely responding to background radio fre quencies With a little experiment ing you ll quickly learn how to dis tinguish between this and a frequen cy locked readout Conclusion Frequency counters are finding wider areas of application than ever before Continued on page 85 May 1989 MODERN ELECTRONICS 37 Project Conclusion Microprocessor Control with BASIC Adding a Tempwatch accessory to last month s Microsys development unit creates a smart thermometer By Jan Axelson amp Jim Hughes ast month in Part 1 of this article we showed you how to build and use the Microsys development system for micropro cessor based projects The basic sys tem described so far consists of an 8052AH BASIC microcontroller RAM EPROM and a serial port for connection to a terminal or a com p
207. solar cell exposed to full sunlight You should obtain a read ing of about 60 millivolts dc Also check the values of the components associated with C and as a final step try a new LM324 in the socket Final adjustment for the project is for proper setting of R5 Set the proj ect to the calibrate mode either by temporarily connecting R73 to pin 6 of C2 or setting S3 to its CALI BRATE position if you incorporated this switch into your project Set R5 to maximum counterclockwise min imum resistance and place the con trol knob on its shaft so that the pointer is at the counterclockwise CCW limit of the scale not the 10 20 40 index shown in Fig 4 Tight en the knob s setscrew and adjust the knob so that the pointer is at the 15 30 60 minute point The easiest way to calibrate R5 is to remove C from its socket and connect a dc power supply set to 5 5 volts between circuit common and pin 14 of the JC socket be sure to observe polarity This eliminates any variation in drive voltage to the oscillator as a result of varying sun light intensity If you do not have a suitable supply available using the solar cell and amplifier to generate the voltage in full sunlight is perfectly satisfactory though you will have to position the project so that it remains stable while exposed to full sun With the supply set to 5 5 volts or the solar cell positioned so that it re ceives full direct sunlight turn o
208. stor in the opening for the lamp in the reflector For best results make sure the thermistor is positioned so that it s as close as possible to reflector s focal point where the lamp filament would otherwise be located Figure 14 is taken from a chart record ing I made of the current through a ther mistor installed in a small reflector The peaks were caused by passing a flame sev eral inches in front of the reflector Ricardo Jiminez G of San Diego State University has developed a respiration rate sensor in which a thermistor re sponds to the temperature of a subject s exhaled breath His circuit is described in Soo THER MISTOR on lt qoo i Wa 300 REFLECTOR MATCH HF 2 w ao 200 a 2 W 1co C S i 15 2 0 MINUTES Fig 14 Plotted response of a thermistor to the flame of a lighted match detail in EDN Thermistor Measures Respiration Rate August 1988 pages 214 through 217 Several years ago I devised a thermis tor based temperature sensor to monitor temperature changes at distances up to 100 feet away This circuit which was flown from a helium filled BPTB other wise known as a black plastic trash bag transmitted temperature data to ground over a single optical fiber You can find the details of the design and con struction of this l ounce circuit in the June 1985 installment of this column It is also described in Forrest Mims Circuit Scrapbook II Howard W Sams 1
209. subtle variations in temperature The photo in Fig 3isof two wafer ther mistors and one bead thermistor The bead thermistor which is the one I used to generate the response curve shown in Fig 2 isencapsulated in the end of a glass capillary tube Since its active area is quite small it responds relatively rapidly to temperature changes Thermistor Applications All of the hundreds of applications for thermistors can be divided into just two categories those in which the thermistor is heated by current flowing through it and those in which the thermistor is heat ed or cooled by external means The first category includes surge protection and timer circuits The latter category in cludes many different temperature sens ing and temperature compensation ap plications e Surge Protection An important appli cation for self heated thermistors is surge suppression The delicate filaments of some lamps and tubes can be damaged or destroyed by rapid application of cur rent If a thermistor is placed in series with the current sensitive component and a source of current its resistance will lim it the initial current As the current pass ing through the thermistor raises its tem perature the device s resistance eventu ally decreases and allows more current to reach the component Careful selection of the thermistor will provide both an ap propriately low initial current and an ade quate operating current To test the ab
210. t items to knock down our l A alg Or yours A Huge Assortment of over 11 000 items keeps you on the road lp sucess whatever your needs may be MUCS On every item with a commitment to quality Exceptional Service means we ll keep you pumped up with all the help you need when you need it mem MCM CLIETTTHITIFISCS Ld For Your FREE subscription to our MCM Electronics Catalogs and Flyers CALL TOLL FREE 1 800 543 4330 Or write MCM ELECTRONICS 650 CONGRESS PARK OR CENTERVILLE OH 45459 4072 A PREMIER Company SOURCE NO ME 47 CIRCLE NO 102 ON FREE INFORMATION CARD Say You Saw It In Modern Electronics May 1989 MODERN ELECTRONICS 7 W MODERN ELECTRONICS NEWS AUTOMOTIVE ELECTRONICS Toyota plans to produce electronic control units for their cars likely beginning such operations in mid year in a new plant that s expected to employ about 1 000 Electronics in cars continues to expand led by digital displays electronic engine control and fuel injection with sharp growth displayed by cruise control electronic controlled suspensions and anti skid braking The U S Big Three GM Ford and Chrysler have long been captive producers of automotive electronics of course Worldwide though independent suppliers lead with West Germany s Bosch and Japan s Nippondenso accounting for some 30 of a nearly 15 billion market THE VOICE HAS IT Computerized voice applications c
211. t when display ing VGA and extended VGA modes on the EGA monitor because of the inter lace scanning Bear in mind too that the EGA monitor is also limited to 16 colors Performance and color options are better with a VGA monitor and are excellent with a multisync monitor like the NEC MultiSync but expect to pay more for the monitor as performance increases If you don t have a lot of money but want high end VGA performance and can live with the limitations of interlace scanning Tecmar s VGA AD board offers an appealing way to go CIRCLE NO 132 ON FREE INFORMATION CARD standard would be an important step forward because it allows software manufacturers to write their own ex tended mode drivers and maximize screen performance for each particu lar application This not only boosts performance it also gives the user a wider range of applications from which to choose instead of being limited to the handful of extended VGA drivers board makers are able to supply VESA is not a standard yet The greatest obstacle standing in the way of it becoming so is deciding on a common timing scheme to make VESA compatible with all boards and video monitors The proposed standard sets VESA s horizontal scan rate at 35 kHz and vertical scan rate at 56 Hz However many VESA proponents feel that the flicker at 56 Hz is excessive they would like to see the scan rate increased to 60 Hz Oth er committee members would like to 20 M
212. tain NC 28718 LASER Image Projectors Complete Red beam scanning systems Red Line 9737 Bal boa Dr St Louis MO 63136 u LASER LISTENER II other projects Bug ging descrambling false identification infor mation Plans kits other strange stuff In formational package 3 00 refundable DIRI JO BOND ELECTRONICS BOX 212 LOWELL NC 28098 Say You Saw it In Modern Electronics Prue MOTN ant ngr 402 u E mn TTI as AOA ix E B 748 ES LI an P a rec 4 aj jaata ax 7581 wp 74 we ha d L Teeny B 74C 160 mery LP 4c 74LS00 TTL Pert rv 74 SOUN 9 7 Mi SOIN x TA SOZN Ev ac 7AL SO 3 MITRCN A 04 i A e7SR CN Tit SOS 3 Ln fat Sog C i i WC 744 SOBA E wn asaca tas Uu w a477m Pe afe Ye BAIN THC 74 34 a 0901 te 5152 p PECON 3 Linear a 205 u RA pen Price Pax 621 yw The y ME X 241 SON mY rece a0 Pe SERN a 1447906 14 SION u AC 14 SRN y qua Ta SN p 74C 300 5 4L SIN p cv T 14 47 o PaL 810 es re amp JAL SiAn p 9 P Lea TALS TJAN a2 ACR 1 5 ose 74 a ac wal az 7Acvie TLE T 227 az CEN jw 25 M emo Ww MMC tm RU po E MINCZ ecc Bossa E a Abia DAKI 4 MO N 7 Peo o Bee VON ge 4a co MORIA 4 MEOS es i MOM 78 4 ares aC ROO ES tls AC 7 LM n NM 9 aoc gan a AMI MP
213. tercard Am Express Signature Acct No Good from Name Address Expires L City State Zip THE AMERICAN RADIO RELAY LEAGUE 225 MAIN ST CIRCLE 31 ON FREE INFORMATION CARD D NEWINGTON CT 06111 CIRCLE NO 116 ON FREE INFORMATION CARD Say You Saw It In Modern Electronics May 1989 MODERN ELECTRONICS 15 A CD Player For Recording Technics Model SL P555 CD player features Peak Level Search with an output signal meter and an Edit Guide that are very useful when transcribing disc programs to tape Peak Level Search checks an entire disk for the highest signal peak and repeatedly plays the 3 seconds that precede and follow the peak to per mit recording levels to be accurately set all done in a maximum of 3 min utes for a 60 minute CD program Edit Guide lets the user select C 46 C 60 or C 90 tape length from which the player automatically calculates the tracks and playing times that will fit on each tape side Alternatively the user can select the tape length and then specify a recording time A disk link key is included for use when transferring more than one CD onto a tape When a new disk is in serted into the player the user uses the disk link key to calculate which selections will fit onto the remain ing tape The player uses 18 bit quadruple oversampling digital signal proces Video Surge Suppressor A new Cable LineTM Surge Suppres sor from Perma Power Electronics Chicago IL prot
214. th low instructions can be received by M1 on ADO through AD7 When A8 is low and A9 is high character codes can be received The applications notes for M de scribe the various instruction codes and their functions They also illus trate the possible characters and their character codes Momentary action pushbutton switches 2 and S3 permit user input to the system Each switch connects to a line on Port 1 an I O input output Port of C2 In the Temp watch program S2 resets the maxi mum and minimum temperatures and times to the present temperature and time and S3 lets the user set the Tempwatch s clock Construction Creating the Tempwatch from the Microsys you built last month requires you to add the circuitry for the ADC sensor LCD module and switches The control program must also be written and saved in the EPROM Figure 9 shows a completed Temp watch mounted in its enclosure Add 40 MODERN ELECTRONICS May 1989 ing the hardware is the first step Here is where the locking connectors we specified for the Microsys come in handy Unplug both connectors and remove the circuit board assembly from the Microsys enclosure Wire Wrap the new components specified here on this circuit board assembly Begin by mounting the sockets for C I2 and IC15 Do not install the ICs themselves in the sock ets until after you have ascertained that your wiring is correct and pow er distribution tests have been con
215. the percentage of college graduates whether two year or four year to an impressive 71 3 this year from 1986 s 47 9 The college trained total which includes At tended Attending College among re spondents rose to a powerful 89 9 from 83 4 three years ago With this information under our belts what does it all mean Firstly we know that the typical Modern Electronics sub 70 MODERN ELECTRONICS May 1989 scriber is in his early 30 s and has been working for about 11 years after graduat ing college Consequently most of you cut your technical eye teeth on solid state electronics not vacuum tube technology Your prime interest in electronics and computers relates to your work not your hobby which only 18 5 of you noted as best describing this involvement Sixty four percent of you are either staff elec tronic engineers or technicians while an other 15 5 are in the management end More of you are concerned with Mainten ance Repair work 37 1 than we had thought followed by nearly 30 with Design or Development jobs This ap proximate 2 3rds apparently represents what most of our reader engineers and technicians work at for a living It came as no Surprise that a great num ber of you buy equipment and compo nents by mail which respondents verified to the tune of 72 1 Purchasing froma distributor or sales representative how ever is another story Here 41 docu mented this largely non personal source
216. through 18 connect directly to ADO through AD7 on C2 CHIP SE LECT at pin of JC 2 is generated by Y7 at pin 7 of C3 Output Y7 is low when A13 A14 and A15 are all high This places 7C 12 at hexadecimal ad dress E000 Reading and writing to IC12 are controlled by RDHI at pin 3 of IC7A and WRITE at pin 16 of IC2 Resistor R 7 and capacitor C20 provide the ADC s clock at about 300 000 Hertz 300 kHz A low to high transition on pin 1 or Say You Saw It In Modern Electronics pin 3 of JC 2 causes the ADC to be gin converting its analog input the temperature voltage to an eight bit word The 8052 can be programmed to read this word on ADO through AD7 and convert it to a temperature Next we need a way to display the measurement Figure 6 shows the wiring for M1 an Amperex Philips No LTN111R 10 LCD module This module has a 16 character display and contains a CMOS controller driver and its own ROM and RAM Each of the 16 char acters in the display is created by turning on and off the LCD segments arranged ina 5 x 7 matrix A matrix display was chosen for this project because it allows much more flexibil ity in character which can be letters numbers or other symbols de sign than seven segment displays do The module s ROM stores the pat ternsthat create 160 different charac ters and the RAM stores display data As Fig 7 shows virtually all of the circuitry of M1 is contained in one LSI surface mount devi
217. tment of the manufacturer of the board will get you the correct infor mation If the particular board you re calling about isn t absolutely register level compatible the person you speak to will tell you which of the company s VGA products are in the 640 by 480 mode plus an 800 by 600 16 color screen Boards that use the Tseng Labs VGA controller chip which accounts for about half the VGA boards in production to day can display up to 256 colors at 800 by 600 resolution A few boards even support 1 024 by 768 graphics Extended text support has not gone unnoticed either Text modes with 80 and 132 column displays in up to 60 lines are also very popular In creased numbers of columns and text lines can make working with desktop publishing programs and spread sheets a whole lot more pleasant May 1989 MODERN ELECTRONICS 19 i i 1 f jf Tecmar VGA AD A Board For All Seasons If you want VGA performance but can t afford an analog video monitor Tecmar s VGA AD board could be just what you need This 695 board dis plays 640 by 480 plus 800 by 600 and 1 024 by 768 16 color graphics on an EGA monitor using interlace scanning It also provides a wide range of stan dard and extended VGA mode drivers including graphics drivers for Win dows Ventura and AutoCAD in reso lutions up to 1 024 by 768 Included is a generous helping of 132 and 80 col umn extended mode text support for 1 2 3 Sy
218. tor oper ates at a frequency in tke 0 25 Hz range hence a predictable amount of time is required before any of the outputs of C2 can be advanced to a logic 1 level In this circuit pin of IC2 would go to logic after a delay of about 8 minutes in full sunlight with R5 set to minimum resistance Similarly pins 2 and 3 would not reach a logic 1 condition until 16 or 32 minutes of time respectively have elapsed This time celay which is a function of the unijunction oscil lator frequency provides the trigger signal that operates the warning de vice PBI Resistor R 3 is connected to one of the pin l 2 or 3 outputs of C2 When that output assumes a logic 1 condi tion Q3 is forward biased This causes current to flow into piezoelec tric sound element PB The high pitched warning signal emitted by PB then tells you that the selected elapsed time is up Resistor R13 is connected to the outputs of C2 through single pole three position switch 3 to provide three possible time delay ranges that can be selected If you require only one time delay range you can wire R3 directly to the appropriate output Say You Saw It In Modern Electronics pin of C2 and eliminate switch 3 A fourth output at pin 6 of C2 pro vides a means for quickly checking time delay calibration without hav ing you wait the full 8 minutes This output because of the internal divi sion of the clock frequency by 128 will assume a logic 1
219. tput voltage the solar cell has been calibrated Say You Saw It In Modern Electronics a 2N6027 1K Q3 As 1 R11 Se TEST R12 CD4020BE zz 2 co o D w ce m e uU AOLE c SUC x 3 amp o x O o g p o v j 6 N eo FOO row OL E l pan 2 Lod u F ao C zi May 1989 MODERN ELECTRONICS 23 PARTS LIST Semiconductors D1 D2 1N4148 or similar silicon diode IC1 LM324 operational amplifier IC2 CD4020BE 14 stage binary divider Q1 2N6027 programmable unijunc tion transistor Q2 Q3 2N3904 or similar npn silicon transistor Capacitors C1 10 uF 16 volt low leakage elec trolytic or tantalum C2 10 yuF 16 volt electrolytic C3 90 1 4F 50 volt ceramic disc Resistors 4 watt 10 tolerance R2 100 ohms 1 metal film R3 5 900 ohms 1 metal film R6 100 000 ohms 1 metal film R7 4 700 ohms R8 150 ohms R9 R13 10 000 ohms R10 100 000 ohms R11 R12 1 000 ohms R1 0 2 ohm wirewound see text R4 10 000 ohm pc mount cermet potentiometer R5 250 000 ohm linear taper panel mount potentiometer Miscellaneous B1 9 volt battery Connected as a voltage follower IC1B provides a low impedance driv ing source for the clock circuit After calibration the output at pin 14 of ICIB will be 5 5 volts under condi tions of 1 full sun and will vary lin early from zero to 5 5 volts with changes in sunlight intensity Pro g
220. tting diodes that make up the sec onds minutes and hours indicators Before you solder any LED into place make sure it is properly ori ented Also position each LED so that the bottom of its case is inch above the surface of the board When you are finished installing the LEDs carefully position them so that they form three concentric per fect circles Carefully check your work as you did for the pendulum board Follow Say You Saw It In Modern Electronics NOTE All diodes are 1N4148 or 1N914 All LEDs mount with cathodes toward center of board Fig 5 Wiring guide for the main board viewed from the component side the same steps detailed above for this operation The length of the eight conductor ribbon cable that links the two cir cuit board assemblies together de pends on how far apart the two Say You Saw It In Modern Electronics boards will be located in your clock s enclosure If you are building a wall hung or mantel top version the dis tance separating the two assemblies will be short Alternatively if you are building a long case grandfather version the distance separating the two assemblies will be considerably greater It is preferable to use ribbon cable that has color coded insulation to make it easy to keep track of which May 1989 MODERN ELECTRONICS 65 IDUENE EILL PC I NL CM MULA EN cert E I H Trwm conductor goes whe
221. u Saw It In Modern Electronics The Compatibility Issue Most manufacturers claim 100 percent IBM compatibility for their VGA boards but not all VGA boards are cre ated equal The problem is that there isn t just one way to clone the VGA Three basic ways exist at present and in clude extended mode EGA boards with VGA software drivers BIOS compat ible boards and VGA register level compatible boards In a BIOS compatible clone the BIOS chip is programmed to recognize and execute VGA mode commands However if a program bypasses the BIOS and addresses the VGA hardware instead the board can t respond to the instruction VGA board makers deal with this situation by using logic schemes that trap VGA hardware calls and reroute them to the BIOS Some times the traps are set in firmware at other times the traps are activated by software from a disk With register level compatible VGA boards VLSI chips duplicate IBM s VGA controller at the hardware level Consequently a program that makes hardware calls to the chip will find the register it s looking for which elimi nates the need to set logic traps and thereby improve speed Of the two register level compatibil ity is the more desirable It has fewer software compatibility problems and is faster than BIOS compatibility Unfor compatibilities by providing proprie tary emulators that bypass the VGA BIOS Hercules Graphics Card HGC emulation is also very popu
222. ublisher Dorothy Kehrwieder General Manager Frank V Fuzia Controller Arlene Caggiano Accounting Catherine Ross Circulation Director Kathleen Bell Customer Service SALES OFFICES Eastern Midwest Modern Electronics 76 North Broadway Hicksville NY 11801 516 681 2922 FAX 516 681 2926 Western Advertising Representative JE Publishers Representative 6855 Santa Monica Blvd Suite 302 Los Angeles CA 90038 213 467 2266 FAX 213 462 0684 Jay Eisenberg Director 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 17 97 two years 33 00 three years 48 00 Canada Mexico one year 20 00 two years 37 00 three years 54 00 For eign one year 22 00 two years 41 00 three years 60 00 Foreign Air Mail one year 75 00 two years 147 00 three years 219 00 Entire contents copyright 1989 by CQ Communications Inc Modern Electronics or CQ Communications Inc as sumes no responsibility 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 Electronics 76 North Broadway Hicksville N Y 11801 Say You Saw It In Modern Electronics Kit projects Heathkit F
223. unc tion to a convenient circuit ground point Then use the meter s hot lead to probe pin 14 of the 14 pin sockets and pin 16 of the 16 pin sockets In all cases you should ob tain areading of about 9 volts If you do not obtain a 9 volt reading at any of the specified pins use the meter s hot probe to check the reading at the positive lead of C1 on the bottom of the main board If you still do not obtain a 9 volt reading at this point check the wir ing of the power supply circuitry and especially the orientations of DJI through D4 If you fail to obtain the 9 volt reading at only one or a few IC sock ets power down the project and troubleshoot it to isolate and rectify the problem Do not proceed until you are certain that the problem has 66 MODERN ELECTRONICS May 1989 been rectified Once you are certain the the proj ect has been wired properly power it down and allow the charge to bleed off C1 Then carefully install the ICs in their respective sockets Make sure you orient each IC as shown and that no pins overhang the sockets or fold under between ICs and sockets Also since the ICs used in this proj ect are CMOS devices handle them with the same precautions you would with any other MOS device to pre vent damaging them from static electricity Plug the project s line cord back into the ac receptacle and observe its LED display If no LEDs are on check the power suppl
224. unger than it was Since the 1986 median age was 36 years old our guesstimate of 3I to 32 years at present is about right on the head Readers holding the title Engineer remain constant at 27 6 27 5 in 1986 Technicians though exhibited a steep rise to 36 4 from 27 5 With Management readers being the same 15 5 vs 15 6 this came out of the hides of other principal titles Educators came in at 6 which adding to 6 2 Professional and Technical Chemists Computer Programmers Physicians Scientists etc totals 12 2 compared to 86 s 13 4 Sales Clerical etc had 1 7 while Craftsmen Mechanics Electricians etc had 2 4 for a 4 1 total as compared to 1986 s 7 3 Stu dents were at 3 1 whereas three years ago they were 6 2 of subscribers and Retired Unemployed came in with only 1 2 vs 1986 s 2 3 An interesting new question was posed this year to narrow down what our reader does during his working hours It was What s your main function This was followed by five choices including an Other category Leading was Main tenance Repair with 37 1 noting this Next was Design or Development 28 9 Continued on page 70 WJA L u E 51E R v 1 c E Fill er Up EME rH on Be With MCM Electronics Your Owe FULL SERVICE Electronic Parts Supplier High Quality Products are 4 you ll find in MCM Electronics giant catalog Never any low tes
225. ur status and pay to the Engineering Level Advance Rapidly 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 COOK S INSTITUTE OF ELECTRONICS ENGINEERING LC FE 4251 CYPRESS DHIWE E JACKSON MISSISSIPPI 19212 CIRCLE NO 148 ON FREE INFORMATION CARD May 1989 MODERN ELECTRONICS 75 Fig 10 The schematic of the Wheatstone bridge circuit perature monitor Assume the bridge is initially balanced This can be achieved within a few tenths of millivolts or so by using a pair of matched thermistors for RI and R3 and identical precision resis tors for R2 and R4 For the test circuit I assembled the thermistors each had aresistance of 2 000 ohms at room temperature and R2 and R4 each had a resistance of 2 200 ohms Since I didn t use matched thermistors and precision resistors the bridge gave a balanced output of around 82 milli volts Substituting precision resistors or potentiometers for R2 and R4 would have provided a better balance If the temperature of thermistor R is greater than that of thermistor R3 the output will be a positive voltage Con versely if the temperature of R is less than that of R3 theoutput will be a nega tive voltage In either case the magnitude of the output voltage coincides with the overall temperature difference between the two thermistors Temper
226. uter being run as a terminal Now we ll add inputs and outputs that will turn the Microsys into a complete stand alone temperature measuring instrument We call this our Temp watch smart thermometer Tempwatch isn t just an ordinary thermometer It displays the present temperature and time and also the maximum and minimum tempera tures measured and the times these occurred To add these capabilities to the basic Microsys you must add a few more modules For input you ll add a temperature sensor an ADC analog to digital converter and two pushbutton switches for user control A 16 character dot matrix LCD liquid crystal display module serves as the output device About the Circuit In Fig 5 is shown the schematic dia gram for the ADC and its associated circuitry Input to the ADC is pro vided by LM34 temperature sensor IC13 The output of this three ter minal device is an analog voltage that is proportional to temperature at a rate of 10 millivolts per degree Fah renheit At 70 degrees its output is within 0 8 millivolt of 700 millivolts Resistor R 8 and capacitor C2 form a low pass filter to reduce noise on the input The output from C 3 is the ana log input that is applied to input pin 6 of ADCO804 analog to digital con verter C12 The ADC converts this analog input into an eight bit word whose value represents the analog voltage 38 MODERN ELECTRONICS May 1989 LM385 1 2
227. y for proper wiring If everything appears to be operating as it should the pendulum should begin moving its LEDs cycling back and forth and at the end of each swing the seconds LEDs should increment in the clock wise direction one LED at a time Pressing and holding SECONDS HOLD pushbutton switch S should halt the advance of the seconds LEDs and turn on the one LED at the 12 o clock position Doing the same with MINUTES SET pushbutton switch S2 and HOURS SET pushbutton switch S3 should cause the LEDs in the min utes and hours rings respectively to advance in the clockwise direction at a rate of once per second If you ob tain these results the clock has been properly wired Once you have ascertained that the clock has been correctly wired press and hold the MINUTES SET button and observe the display to check that all 60 LEDs light in proper sequence Allow the LEDs to cycle completely around the dial face three or four times Then do the same for the HOURS SET switch and the 12 LEDs that make up the hours ring If a trailer appears in either dis play there is probably a leaky LED in the string To isolate this LED note if more than one group of 10 LEDs comes on If so there is more Say You Saw It In Modern Electronics than one leaky LED In any case find ing it or them is a relatively easy pro cess As the turned on LED moves around the dial face a leaky one w
228. y turning off the 2 o clock LED The decade counter now advances until its 9 out put at pin 8 of C10 goes high At this point the output at pin 3 of JC A is forced high thereby selecting hours LEDs for 1 11 and 12 o clock Construction Printed circuit assembly is highly recommended for this project both MEL pO ELLOS A EE OU OLAAULLLLSSGCELLLOLLU CILUGLELLUGGUKR CLO ISLOBGLALUL May 1989 MODERN ELECTRONICS 59 Fig 3 Actual size etching and drilling guides for the component left and solder right sides of the main board 60 MODERN ELECTRONICS May 1989 Say You Saw It In Modern Electrorics Fig 4 Wiring guide for the pendulum board viewed from the component side to simplify installing and wiring to gether the many components espe cially LEDs used and to reduce the possibility of creating wiring errors Of course if you wish you can build the project on perforated board that has holes on 0 1 inch centers and us ing suitable soldering or Wire Wrap hardware If you go this route you might want to arrange the dial in a square or diamond pattern with 15 LEDs on each side for the seconds and minutes and 3 LEDs on each side for the hours displays Two printed circuit boards are needed one for the main circuitry and the other for the divider pendu lum circuitry The latter is needed even if you decide not to build the pendulum into your clock because it contains the circuitry for t
229. you can tailor the Mi crosys to fit your own requirements whatever they may be ME REM check for switch press 4508 REM WHAHHHHHHHHHHHKE Rt clock subroutine hhhd hh dededededededededeh 4608 XBY 0CO000H 91 REM clear display 470 COUNT 24 POS C2H CHAR 58 UNIT HOUR GOSUB 516 4808 COUNT 60 POS C5H CHAR 32 UNIT MINUTE GOSUB 518 490 GOSUB 7360 500 RETURN 5198 REM h htbhk t tt t taor hours minutes subroutine hhddhhhhhhtdthshxsn 526 DO XePORT1 4 INT PORT1 4 UNTIL X gt 1 REM wait for switch open 538 SELECT 0 5408 DO 550 IF COUNT 24 THEN J 1 ELSE J 0 560 DO 576 DELAY O 588 DO 598 DELAY DELAY 1 600 XBY C H POS 618 XBY 0C200H 9INT J 10 4B 620 XBY 0C200H J INT J 10 10 48 636 XBY C266H CHAR 646 X PORT1 4 INT PORT1 4 656 UNTIL DELAY 6 OR X lt 2 660 IF X 1 THEN SELECT 1 TIME 670 J J l 6860 UNTIL J COUNT 1 OR SELECT 696 UNTIL SELECT 1 REM set display postion REM display digit 1 of hour or minute REM display digit 2 of hour or minute REM display colon or space REM check for switch press 700 IF UNIT HOUR THEN EOUR J 1 ELSE MINUTE J 1 718 DO X PORT1 4 INT PORT1 4 720 RETURN UNTIL X 3 REM wait for switch open ATTENTION VCR TECHNICIANS VCR REPAIR PARTS KIT Now you can do most of your VCR repair jobs the same day Parts Express VCR Parts Kit makes this possible It contains over 45 of the most commonly used parts to repair
230. ystems pro duces a Matrix 1000 Editor Librarian package for the Macintosh that allows you to modify and create your own patches for the Oberheim unit The resul tant patches can bestored on a Macintosh floppy or hard disk and from there down loaded into the Matrix 1000 when you want to use them Dr T sMusic Software supplies a simi Creative Music Systen s Intelligent Version 1 04 Copyright c Creative Music Lab 1988 ALI rights reserved XI move cursor BET previous JG next SITz select NW resume Intelligent Organ s keyboard covers four out of a possible seven octaves Heavy bars above and below keyboard indicate currently active range Box below keyboard shows available prerecorded songs lar package for use with Atari and Amiga computers These software packages greatly extend the Matrix 1000 s already considerable capabilities The Matrix 1000 is certainly not for everyone At 595 without a keyboard a beginner would be hard pressed to justify the cost But if you want to upgrade an in expensive MIDI keyboard or if you are setting up a first class computer driven MIDI studio and don t want or need the keyboard the Matrix 1000 is first rate It s small about 17 square and 1 5 high has usable documentation and produces lots of beautiful sounds and some pretty strange ones I really like it The Creative Music System C MS Up to this point most of the hardware and software we ve dis

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