75:76 July August 1981 UK. 120 p up-to-date electronics for lab and leisure elektor july/august 1981 — UK-03 eontente summer circuits 81 page one 7-01 * 1. scoreboard 7-02 v 2. 'hi-fi' pre-amplifier 7-03 3. 6 watt stereo amplifier for a car radio 7-06 4. 'chopper' front-end for power supplies 7 07 5. loudspeaker peak indicator 7-08 6. polarity converter 7-09 7. temperature recorder 7-10 8. end of tape detector 7-11 9. CMOS pulse generator 7-12 10. fuse protector 7-13 11. protecting dynamic RAM's -. 7-14 12. russian roulette - P. Dooley 7-14 13. miser-LED 7-15 14. power-assisted NICADs 7-16 15. zero voltage indicator 7-17 ( 16. auto theft alarm - R. Rastetter 7-18 17. phaser gun - E. Vaughan 7-19 1 8. random number generator 7-20 19. an effective scratch and rumble filter 7-22 20. digital tuning indicator 7-23 21. objektor 7-24 22. high input impedance voltage follower 7-24 23. LED audio level meter 7-25 24. power MOSFETs in the car 7-26 25. simple swinging poster 7-26 26. six hour timer 7-27 27. VOX for PA systems 7-28 28. variable power 'resistor' 7-29 *29. auto reminder - W. Gscheidle 7-30 30. adjustable square-wave edges 7-31 31. silent disco deck switch - K. Kirk 7-32 32. electronic gong 7-33 33. simple short-wave receiver 7-34 34. keyboard encoder - C. Voss 7-35 35. input buffers for the logic analyser 7-36 36. universal measuring amplifier 7-37 37. digital sinewave oscillator 7-38 38. transformerless aerial amplifier 7-39 39. battery supply timer 7-39 40. power stabiliser 7-40 41. constant current LED 7-40 42. Kansas City demodulator 7-41 43. signal injector-tracer 7-42 44. solar powered pocket torch 7-43 45. american billiards- H.J. Walter 7-44 46. CMOS ultrasonic receiver 7-45 47. constant pulse width oscillator 7-46 48. single 1C siren 746 49. pulse generator with variable duty-cycle 7-47 50. differential switch 7-48 51. remote control potentiometer - R. Behrens ... 7-49 52. variable 2 V ... 60 V power supply 7-50 53. long-period timer 7-51 54. novel clock control 7-52 55. novel flashing light 7-53 61. voltage regulators in parallel 7-59 62. EPROM light sequencer 7-59 63. fast TTL interface 7-60 64. stereo level controls 7-61 65. optical indication for the movement detector . . 7-62 66. 6 bit keyboard encoder - L. Witkarn 7-63 67. forget-me-not-transmitter 7-64 68. forget-me-not-receiver 7-64 69. humidifier - B. Darnton 7-65 70. automatic soldering iron switch - M. A. Prins .. 7-66 71. constant current adapter - R. Storn 7-67 72. simple ASCII keyboard - from an idea by D. Hul 7-68 73. hydro alarm 7-68 74. automatic reset 7-69 75. LED voltage monitor 7-70 76. word recogniser and delayed trigger 7-71 77. humidity sensor 7-72 78. crystal oscillator ... for low voltage supplies . . 7-73 79. 6 to 1 2 volt converter 7-74 80. 1 2 to 6 volt converter 7-76 81. touch-sensitive 16 channel multiplexer 7-76 82. dual input channel selector 7-78 83. 16 input channel selector 7-79 84. post office letter scales - K. Hense 7-80 85. mains LED 7-82 86. low noise parallel resonant oscillator 7-82 87. caravan connector tester 7-83 88. universal digital meter 7-84 89. high power motor controller 7-86 90. ring counter using timers 7-87 91. crystal tuning fork 7-88 92. dynamic RAM power supply 7-89 93. local oscillator for 2 m transceivers 7-90 94. bar graph driver 7-91 95. microcompressor 7-92 96. 3 in 1 pencil holder - W. Gietmann 7-93 97. six channel A/D converter 7-94 98. speed controller for model boats 7-96 99. active notch or CW filter - H. Pietzko 7-97 100. automatic car aerial control 7-98 101. D/A converter for motor control 7-99 102. continuity tester 8-00 103. frequency and phase detector 8-01 104. power failure forecaster 8-02 data section 8-03 advertisers index UK-22 We regret to inform readers that the technical queries telephone service will not be operating during the month of July and August. elektor july/august 1981 — 7-01 summer circuits issue . . . . . . one of the most popular Elektor traditions! Once a year, we do our utmost to produce 'over one hundred' novel, intriguing and original circuits. Furthermore, every year we try to do better than the year before. Not so many application notes using brand-new (and therefore not-so-readily ob- tainable) components and more truly practical cir- cuits, covering a wider range of topics. In the ideal case, every circuit should be fully tested in our own lab before it is published. In practice, this is always true for our own designs and for projects that are published with a p.c. board. The remainder (application notes and external contri- butions) are all studied carefully, tested if possible, and otherwise treated according to our motto: 'When in doubt, cut it out ! . Of course, tradition also dictates that there must be a 'Joke circuit'. In the past, we've had a Fuse Destroyer, a OV Reference and a No-noise Preamp, to name a few. Often, these will also work - in the sense that they do exactly what we specify. This year's version doesn't work. (No, we won't tell you which one it is). We are often asked where all the circuits come from. Application notes? Yes, a few, with reference given. Readers? Again a few, with author's name included. Preview of (parts of) coming Elektor designs? Very rarely. Our own design, purely for this issue? Yes, usually! So why 'waste' them as one-page articles or less? Because we promise 'over one hunderd circuits’, that's why! If we gave them all the full description that they merit (or that some magazines would give them . . .), this issue would be a fairly thick book. So we squeeze them in. One more 'tradition'. Almost, anyway. Over the past few years, we have come to associate the Summer Circuits issue with a competition. Last year we had 'Canned circuits'. This year, various different sources gelled into a new theme: Photography. Most Elektor readers are photographers, and many Elektor covers are based on photographs. So why not let our readers make 'cover' pictures?! It’s certainly worth a 'shot' . . . The competition details are given separately, but the basic idea is clear: use up the last few frames on that 'holiday' roll on something electronic. You never know: your artistic creation may win the jackpot! And what of the future? From the September issue on? Who knows . . . We'll do our utmost to 'surprise' you I 0ft#l electronics in focus Electronics and photography are two hobbies that often go hand in hand, and so it is hardly surprising that many of our readers are amateur photographers. Furthermore, electronic components or complete circuits on a p.c. board can be very attractive and colourful. An often-heard comment from the 'uninitiated' is: "I don't know what it is, but it looks very pretty!". Developing this idea a stop further, and without implying a negative view of electronics, it seems worth a shot to make it the subject of a competition. To put the whole idea in perpective — and give a clear picture of the wide scope that we have in mind — it is worth looking at Elektor covers over the last few years. They all relate to electronics in one way or another, and they are often based on one or more photo’s. The rules of the competition are few and simple: • the subject must be related to electronics; • only colour photo's or slides can be entered, and negatives of prize-winning colour photo's must be made available to Elektor on request; • the deadline for entries is September 15th, 1981 ; • the decision of the judges is final, and it is regretted that no correspondence regarding entries can be entered into; • all entries become the property of Elektor Publishers Ltd. Since electronics and photography are both expens- ive hobbies, we have decided to offer cash prizes. The total 'prize money' is £ 1000, divided as follows: First prize: £200 Second prize: £100 Third prize: £50 And 25 runners up will each receive a prize of £20. Furthermore, there will be 50 free Elektor sub- scriptions for 1 982. All in all, it is well worth taking a new view of your electronic 'junk' and then, having got into the cor- rect frame of mind in the process, slide out of your easy chair, roll out the c amera and start shooting! Send your entries to: Electronics in Focus, Elektor Publishers Ltd., | Elektor House, tO Longport, Canterbury. Kent. CTt IPE m 7-02 - elektor july /august 1981 scoreboard . • is intended tw. ’ ,or u, ;„“boT *S »«< » c “«>'•»> * SS£-«ysa^-^- counting up and t created by eithe o “ un, „S.». -’t S ■- s“™ “« counters _ . output . -rh is 1C carries out all the 1 IllitfP u iie apparent that t ( [Qer audience is I rnmmm msmm i sggss gate current of 5 mA. 74248 must be .used I ssssssssss 247 take extra caie nent version. 11 n&n ® ® ®®®® elektor july/august 1981 - 7-03 hi-fi pre-amplWi er ays. there are quite a £ u^lycootahi the ?on the « necessary it. v7«"V -3 mV magnetic cartridge 22Q m V tuner _ 22 q mV tape input 50 kO su“srr<-»" ; «?.„»« bass boost/cut. , 13 dB (10 kHz) treble boofl/cut: < 005% ,f . 1 kHz •«« Harmonic distortion . oot put level of 775 m »».. .««"«<* 3 tone controls in t e harmonic distortion, frequency response: . 1 pq after which the bv « •tr'i.roXp * &&&** SSBWi- H18/fH9»P4. )o , pr>«W"<” 2 “ Th« requbeb '? v res'*” ” S 'f. p£«M b, *n “Sn< "»«« *“ £ TM *«'»« X*! to” f,9b'» 2 > ” Resistor.- R 1 .RV.H 10 .BW - 47 k R2 R2- = 180n R3.B3' - 820 « BK 3 ?— * R9.R9" “ 22 ° k , R11.B11' = 2k7 R12.B12"12k R14.R1 4 ’ - “k R15.B15' - 47 ? k R16.R16- - 1M* R17.R17* * 39 k R18.R18--680« P4 = 1 k LIN potentiometer STS.cr-bf’ 0 '' gg-.^'Sv 05.08' - 15 " C8.C8- - 68n c9 09- - 560 P Cl'l CIV - 10M/10V ci^w. c \ 8 -; oon C13.C13- - ’ “ P C14C14‘-2t*2/25V 015- 1°° ^ Ci6 - 470 p/35 V C17 - 330 n r. connected directly t d is connected to the series transistor and the sec , powe r supply actual regulator input of he q{ the senes The output to the extra circuit, transistor is also fed back m The circuit °P erat « ^^r'lOircomparert “eCluge applied to the non ^H a pP' ied to the inverting collector voltage. M ' J he voltage at the mput. The 5V6 tenerdiorteke ^ (ower than inverting input of t P^ Qutpul of the opamp that at the . c0 ' lect ° e thyristor every time the coltertor/emi?^ yog* ^ smoothing SSJt recharged brjfWer supply ^ich is ^sSi^sSss?-r diode *"d i“ °T ! ™1\ a“d .ernaine independent it is always under P owe . T he 741 receives its Of the pulsed man vo l,,g. stabilise' SS, » IC “ "SS “p«S« 3 nrinciple with any power s pp The value of delivering a maximum 001?.^ ^ 2200 pF per 'mpTother 9 words, the value given W700£« rr,,-™ *■ 0 fT^» W^fuceT. sxK.’sKSsKarTsriS ,„d , h , to include an e«re safe side, d may b t)i6 base 0 f the po 470 resistor in sei i« transistor . 7-08 - elektor july/august 1981 loudspeaker peak indicator Nowadays, any .^"tJrough treatment. H ° wever ' „,»ly.pratty-a“S»">“^ , Sln t room •">« > « problems can arise i ougll for clipping “ volume is turned UP “®\,.„tial distortion and occur. At that P°'"* ! “ er ated. This does not higher harmonics can t« 9> „ „„ actually only SPO'I ,is, * nl ™ P i measure of protection can damage the tweeters. A me ak in dicator, P® ■^ d „, b , , .t’ ll no,“m.»y -?*> * «” “i 0 "’'' ?hi"lnSo- d^SaSS “e-«S making it hrfrtV „ othe r words, it is not amplif ier is about to peak l power level at in st an overload indicator) nd (that is, the ?Sot^ sirsfers* 5 S, SS ,h, volume down a httle |nd|c , t0 , „ lh own in The circuit diagram figure 1. I» P™» ■*»* *j£S I* Cf which Is charged «“ R ' * ^ lvJ rect if ic „ion was can be used. transistors are switched off With no signal input all c2 - |$ virtually ml. ^nd therefore current dram ^ a certain value When the input signal lev ' e * he v0 | tage at die dependent on the settmg ofPj. a which junction of FU anQ This switches on * T1 imll start to Jifjanhliy 1 Resistor R7 has been causing c ’ “ charge rapiorv mrd sl» J, larger type Components required. & R9 ■ 3k3 pi° 100 k adjustable potentior Semiconductors: 01 =1N4004 D2.D3.D4 = 1N4148 05 = LED T1 T3.T4 = BC 547B T 2 = BC 557B etoktor july /august 1981 - 7-09 f"”' *,*,te d with the formula'- Connect the lndW» i5« 5cSS» Do, in 9 *■« iSS? ‘jt“ 'f™ dia.ipation limit of T4 be connected J° one ° one 0 f the speakers. It r,' « r ^«* » r di o, .»vs»” SK* « relay that rings a bell • • • mfiipd the common mode potentiometer P3. Thisisca polarity of the Section ratio l 0 ""™ ?"“Vod M VI. A cer«" ! v test voltage ls M th ®" iU no w be measured at voltage (several 0 nce more to reduce polarity converter ^S®^2 ££b sHir-s::;’.: Srr-«Ss':r, russ » » ““ n! pr '“ ss^rvtsa^wsS “is fK; a inpo p , 2 » r . d *. ootput VOW » S correctu calibrated and The circuit will no ready for use. the circuit should oe S'’.o»'»r.«"« ““ Analosoe or dVItrt JjjfJJJ'Sj'ilSronW ’^TTk'SSTJ pm'^stSSTn Z be measured Forgetting to do this one measured P dsastr0 us consequences. . could result in ratherdisast matter s consider- The circuit presented hweh^ always be positive ably as the output voltage . voltage. The S”t«d !o . minimum iw.lb*m»nso 7-10 - eiektor july/auguit 1981 •,k a certain amount of ^ This circuit, t°9«* er it possible to construct - mechanical ingenuity, makes _.t P nt which --I? 3SSKS8K® s Sa-ssi,--— ■ BSSSrSa^--*. IC2 The control ° ut P u Rders who would like to * * A - * , , ul , p( i t o obtain the data 5--SS5.SSSS— — - distributors- of the resistance »a|u® JSJS i ,f TLit X of? P-bien. r«cr : sSr-™rs'^H iMiich effectively set the an •taktor july/auguit 1981 - 7-11 ^o per decree of sffiSSJrs.-'rsSS S* sii"--rtsst The mechanical P arts ount ed on a clip over the ss*^SSf=arJKSS IgSSSSrrs . in nrinting calculators, naner can be the type used P d constant ST. »? ro.l *■>-« l~« » f° W 0P«r.tlo". Th« speed when the equ ' p "*" th the aid of motors and p^Jer drive can bern^e £ th model boat builders gears that are " or ™'^ ^odel s hop. Failing this available from J«V d of v0 | ta ges are readily own care should be taiw.. NTC ^ow 0.5 V. it ■ suffer considerably. end of tape detector -c a new type of photo- This design IneorpowW number 0 f applications detector which ha ' 3® magnet i c tapes. Before such as detecting breaks^ ^ t he outside the output of *b e through the followmg world, the *'® r 5?{ te P ^^rto-diode is followed by a internal stages. Jb P Schrnitt trigger. In turn, linear opamp which feed „ ed . to tem-pole the Schmitt fluctuations in power Basically. th« J* ol tta (*«£ Xc“"o;V,r.n P d ,.»hsis,.,T- •orf The normally closed b!eat e de m te°ctor in magnetic wp» ,e, s0 that The circuit is cor^J^i asymmetric the power supply can be '< conjunction with 5 V type. When the unit « used ^ ^ that the a “^dIte 0 ctr r, sS!ou.d U be PC^J^SStS is detected. 7-12 - elektor july/august 1981 CMOS pulse generator Apu , S ,,n e , r .o.n« r ; r ^,:S designing digital circu • f|exible as possible. The possibilities it must be « over , fairly clock frequency must “ must be variable range and of course the ' P“ , contro l would be a also. An automatic output feW other features _ a dvan- T he u » =' W°f ® po»« «- tages. In the first P' ace t ^ 0 re. the large supply circuit from ba "f '^J^cMOS. from 5 to 15 V voltage range a«orde by aut omatic output makes it P oss,ble . l ° d ° This is clear from the fact control mentioned ab °y«- J b powered from the that if the pulse generator itse vo|t b g e ^ equa | that circuit under * e * £ | 0 gic levels must there- •nrlnded) Furthermore, the low put buffers s'* " generator input results m current requirementofthg being tested a very low current drain on ™ at t he clock The description of the ci gn asta ble multi- nenerator. IC1. This 1C is wire . b|e between vibrator and its J' equen d ^ Q ^ supply voltage) by 2 Hz and 1 MHz Wj***?^. With S5 closed and potentiometer PI an " ru n continuously. c 4 m the high position, iu can be used to With S5 opened an externa socket. Switch S4 can iss «■- - The output the Q output (pm » pin. 10 and i ,„ D utoflC2.ThislCisuseP»t passed to the S'°„ ,„o» syne P"'“ set to delay out. “.STy ^ pulse „,dth to the trigget input of ^ J diu , tm ,„t of both P3 can now he achieeedbv the cycle output and S3. Tb” b. r r?1ci Depeodiog oh the position at Dins 10 and 11 of IW- » the inverted out socket. slektor july/august 1981 - 7-13 ■ to the Signal can be carried A further nwdificat'on t0 the 'delay r m nut signal of IC1 t“® IS possible to delay Now by adjusting P2 and S2, t I* 25Q mS wlt h that the delay ™“ el.hv. to the ** «“ , signal but varies its timing ^ suitable va lue. it s out By setting the del ® v , edge of the output ’SLR S' -r -*• form to be studied. i=B§#f§i mounted oh »>• ““JVjtih. Mountinj ra.iators interconnections to « a be takeh. B'hl» compatible. /^AW 6230 ) (RCA apphca tlon not fuse protector „. !tt issue of Elektor we earlier Summer C™^ ^ destroyed. • published an ar , w effective and worked e 'Y circuit which was “ttlW en deman ding on replace time. Ho«a.er. it»» r«« 0 ' 0 ' d«“” „ it h,tand powers of UP » transformers can easily 0 n' current of the 1 kW in some cases. T impedance, both transformer goes ' nt ^ 8 sec0 ^dary winding. Furthen in the primary and 1 the _* the dc side can be more, the soothing capacity discharged ,t can v r- presented "with a J'^eTwow '^"occasion, limiting the surge current via approximately mS $™i«"™e rr'eapS” fSbiiik TranStor T 1 it then turned cm triec remains on. This m «*"*■» 0 ’„; d e , short across TIC 226D I*' *°tvA Larger transformer, will obviously '*0““' '* ,9 j”“e‘used for a variety of infra-red types. 7-14 - elektor july/augutt 1981 11 protecting dynamic RAM’s . oAM'e the 4116. I On. of 0. most fSS. -JW- N °>>” s I u „lo.iun.Wv L’ .“Kth th. most «*■“; I c,n be done .boo* this, «•" * meets Imply th* 1 and circuit. Althounb arbitrary I then supply «d«l“ jyj* true in all dram- I sr*" ™ <=*** sss.' s? ?.«"?> 1 stiwsr^r* •• ■» - ,,d - account of the sequence. bad as you might I In practice it is WW tion 0 f overshot I consequence of this is I sc'r£r;^ K“fortS n ’t".lvJ.J ”"* iV b '„ P ^" ’ Until ’the n.g«i«e «°» ^.edited. This pbsitive *»■ *”£, V d „, b |, demend on tbe ,h ' rv^'SUn-^VodsuPPl,^ The BD 437 IS . ~» n * 7805 and 7812 ;r .S ■>» ^ *~ ,d « mowided^vitb a small heat-sink. 12 Dooley . russian roulette popular (71 W*"“ ,, I' S is placed m one roulette where a sing bu other five empty* chamber ol a a«*r™„ ,h. exact position The cylinder is then sp -contestants elektor july/august 1981-7-15 - --si rss» -ft vibrator »W> • "$ ,„ constructed switch. St. P» dS“.. i Dt ”"d “4. Th^ 1 ” “S" switch rremented every time the ® . cl ; c k’ is produced if&s^rrh-ics.i.^.o^ r^r.:s-s» 3 £t&s JS points 0 ; tor CI is The circuit °P erates R2 0nce the potential across charged via res ' st ^ ffcient t o overcome the bias this capacitor “ ^ p2 the in put presented by n( , can be made resistor, R1. 'l^^ rel stance wire. The potent.al from a short piece ' f 4“' a ‘ n integrator instructed 5y m.kWg « s “*2 ,™ "r.o.i.tot Tl. When cells are then charged T1 cont ,nues to are no longer under oaa. b) - hes that cl.t, » s --t*3S. , av» maximum amount Qther words, about o "“ ,or 9M ‘ ’ adjusted so that with f the cell capacity- through R1 ,s ° n rl lTvSudinga (rnilliiammeter This can be measured V T his adjustment >s in series with R1 . 8t m ^ be carried out carefully, — tni : St as operate with !•» ‘“TaW the toPP'V »» '*»' voltage of less than S volts. A bined voltage within these limits. H zero voltage indicator i cn's to show Thhxnt volt«.iP ,l '«2L“S”°,Wo . specified whether the W"'™'" C “?“,'iVhTt smell voltage range, «** “" ^ L6D -, ll.sti. It If the voltage is within th ng contmnoiniv I" outside, 'rJiselsoanindicat'"" Within the specd'ed raW ' 0 f tM „nge, or of whether the «"««* '* "„ o) At the centre of ED'.f”sh,«gu'ar'V.P“t,”* , “ d ‘'h' u “ actually quite simple, The operation o. *. ? „ from the although it may h circuit without som diagram. If y°o 01 and D 2). you have the components (R^R4 However , b y includg a normal op-amp®* 5 ensur e that the the potential divider R7.R^ , equal to the voltage fed bade ® C* 1 b y D 1 and D 2) If aiiooIv voltage. (It is also but to a Db R5 P is not now the D c level of the voltage (the input ged .When this )•*•!» ^SlSg^o-rtheh-., lights con. ”;£oS.ft-r then ^ „ ,h. The sensitivity of to a continuous light at LED’s change from A®* can be changed readily plus and minus 50 mV hs ^ resistance bv altering the value of R/- ^ 3M3) Y ou must increases the sensrt.v ty ‘^max^ C1 mUSt bear in mind that if «/ 7-18 — elektor july/august 1981 . ^ door lA : r. Rastetter , Tta auto theft alarm ^ v€ri?S r»». <* sr»* “»•, ssnrjss. »T». * for this purpose must ^ and c {aUsafe . th a. reliable; b. easy *> 0Pf" • woken up tr After all. if ««* J^oSasions due to fa » several times on P rev '° t0 maintain good re <- alarms, it may not be y therefore be less t jsrrTn^£-< » *• >*' ! good features. 'S”,laye™ alarm, it has repetit»e fairly complex. The J,, O i,coit diagram, become clear a. «. STiSShed on, by means of sufficient toturnthe '"si $ ^ , f , dooris activated and is m the stan^v ^ ^ make and now opened, *e d the a | ar m has bee operate relay ^ ^ has been o^ned. it can S°„» ■-“".Sr 1 '.."'-' P”" s ,” ■JSS' 5— ” wch b 1“ door Wit* ' S2- ^ '''"“i'it dy'wj* 1 ™ 1 ?.« “ rcS'.'^ d» S 3K *S5r?KS?-«- — - The other contact of the V A t , h , seme I charge O-'h ,«m has been triggered I dm., an mdm.tt"" «“”h ,pac tor C2 1 is given by LED D • alarm delay time, I via resistor R 5 resu'tt m the kno w that an I « Pin 2 d f N I,e“5?^nd N2 to th. relay dmer I through gates MV « J be acti».tad I rrriim-ii-ndr^ „ « r Capacitor C3 wi« J» ” rge tim , is s.gmf.«mlv I i‘™r ‘and » ^“e ' I potentiometer P3 up P f N3 w ill go low, 1 hi s.% 0 s*"b'“fi-sri“ a » m rr5i: multivibrator and circuit. This 1C is I repetitive feature of the »ia „ triggered at f, enabled by relay “J”“f it the monoflop •*« pin 2 via ratirtdS^anSf potentiometer PI) has | of tim. ladjustable MMPJ^JJw vi , tb. output^ to elapsed, tranststor . C1 t h e n dtscharges ”, tb. 656 .'.SrIo K ^transistor T1 ».« ■« ,”5 througb ''•f” R ,„„,s Cl is reduced to about 1 V. S *• ,0 '”t S ,o drop out and capacitors C2 II is This causes 'e'av Re ; a re sistors R3 and R6 „ is and C3 discharge rapidly ^ the ti mer 1C s , r 1S respectively. A»J* supp , y . The alarm is now in and the original active standby s«te. N4 a , s0 Ke 4011 I'd) containing gat« ^ al(eadY serves another purpose a$ a sqU arewave atvdfot lights operat ed by R.2- elektor july/august 1981 - 7-19 s~] r =MSiSi ESS .3 • 5£S:3*S — “ obvious reasons. ^ stan dbv condition. circuit is a mere ** H 17 now replaced with a series the original circuit arc " respectively. The siss'ss" Phaser gun j lirP a sound which up to a sound that coul *e derived from the such as 'Star Wars’. The published in the sound iM I ” .h»”" l*» March 1981 issue of Elekto minor modifi- etactW « «"*;"£ par. numKrs ™* cations. Th. ™" ' “ ' Srtain item. »• seem rather P®?V*'5 This has the advantage that .the and some are added. This n ^ exist ing prmted circuit can^T 011 "^) Components and/or wire circuit board (EPS 81 1 1 mponent overlay of S >*“ « S5 I SSsr— a iootr higher ™ , ov 3 frequency - ootpnt auency of the second osciHa ^ the frequency setting of potont.orneW Ms „ y vary ing than r tx: obtained. 7-20 — elektor july/auguit 1981 ran^^or ,« uery often required , random number programs on a reasonably 1009 ^cle hesper{ectl randomisation closeiyaPP makes use 0 f an 8 bit Thift register (^^5^ vieEXOB jsaasr-Srsrsis^S Sd. IS ' 27 bl ”. H L , " i S So .stable register •<• f™ ^'S,. R2 .nd This Is in fan M Depending on the pa ° a nd one or more as. ska. s— " the random number. ^ |inked t0 a Where the generato parallel input or an processor system. v» » P is , of course dr.ss.bl. t."«e'- , em ,i„der ol »•«“” required. Ttr« « >* , w „ register tKB comes in. The op of the th ree-state connected to the inp buf f e r are. * th. p,oc«». “• t no ; i s. .n SnSmg 3 " 4 bit comp.rrrtdrs l k elektor july/august 1981 - 7-21 (IC4 . . . IC71. Th* aredby the micro- f . the 16 bit addres random number Jr with the address of the ".no. ^ VM0S r When the ™° t „ lb |« the buffer 3 r T1. turns on whicn ^ output fe.fr.b tor can be se t up .on » * ei P< ' , inks between gore 2) by soldering sh t ^ Qr gro und. st^i-ssiira'.w batween the Jres that an inverter be ieqative strooe m trobe signal. C2 = SOM'’ 6 V „ C3.C4.C6 - 100 n Semiconductors^ T1 . BS 170 , C1 . 4070 ,(52-4016 , |S."c 7 5 4 |C6.IC7 - 74LS85 * powered *om the existing microprocessor 7-22 - elektor july/augutt 1981 19 an effective scratch and rumble filter Many t>o™-comtruo«d a-* J olSnV »" d '™“* 1 » •"fw: ' struction of a stereo a g per octave. The roll-off of as much 35 c h a nge-over switches and contains four electron ' C h co nnected to the input the wiper of each switch o Each e ,ec- of a non-inverting unlt J ^ on e of two inputs to »>«*„ TUSi ££""»“ : P S'r im= Tlbl. fllnr- «*■" !,i,o.p.cton“*" d channel inputs are co c opamps. With ss&rsys „ch channel- The,, cons* and C5 and resistors R2 R4 a^ Rg Rg and RiO hand channel and C7 Cb. rating frequency scratch '■'"•'■'''S” SchU ,h ' 1 P n b _ the scratch filter swu {e(J una | tere d. signals from the first two opa By closing S2 to the inputs of the las arating frequency of a low-pass filter wi* X is activated 7 k Hz and a roll-off °f «dB P c e omponents for the in each channel. The tute C1J C14| R11,R13 l«**h“* .ffSSe for the right-hand channel are C17, Cl 8, C19. R^.RI^ an. ^ Qpamps require a The four inputs of t j ^ acconn pfished via the certain amount of bi . the bias resistors potential divider R 1 R3 ■ t of galvanic P R5... R8- As , r -S 0 ns 0 f the filter, the coupling between the bia$ voltage . other inputs do not require characteristics of S S- -»* Of switches SI sttttt U-il-H aJektof july/augutt 1981 - 7-23 ^■sszsm =ss^~. iliESSs=-- 20 : •tss monolithic Win »o osci „ ato , with a W a 3 Vi digit LCD. a ay timing. As we ■2g£&s=g£ =.S:=SST= frequency of .fun.-. counter. The . frpauency meter, or _ . oqqg 1 Upto16FM3 ^s,rs». s r ?■»£ arp required other u The diode ponents are m selected by 51. , The functions ca correct setting ° matrix provides ,or The signa ls required required frequency 0, ' set [ iver frequencies are t fed via a transistor stag t input lpin 38) Jc, 2318, and from there , of the counter 1C. , ypa 0 , , C i. .lo» V t ££& moreVeasonable, they ■" “ H cheap. (OKI application) 7-24 - elektor july/auguit 1981 21 objektor totally independant of th « )ong as it remains (dead, alive, stat.c ornwrg. f the circuit can within this range. The sen ^ preset ^ „n to- be set remotely by ^ ^ out sh0 e leather meter PI. This'S to ««» error) align ment pro- during the initial '"Iking up and down to obtain cedure - repeated y particular range, the optimum settl " 9 , ° , icat ion of the circuit is its A rather innocent r _ as the sensor use as an invisible d ° or ° e house The most im- could be located tl l" S Srcu?t is the Clapp-oscillator portant part of the c' cu The capacitor constructed *ounJ«3to^eries with the coil U that should be connected ^ t e ^ ^ object t0 be 5eS? £. .o1 h .lo». <.<>«• “P* d, ° r ' output from the orator is ' a single amplifier stage ' on0S table functions are Schmitt trigger and ^ 1 d T4 . VMOS FETs perlormed by F 3 ‘ y Ml been chosen to the » “ ir>d with respect „ct that less t „, ..liability (actor to bipolar S'lc wrongl'l ™. d °“ £ SS bat -It. »=> ■>' ' h< “ sr ■srs in noisy environments ai ^ possess f T r^-t— o 22 ••"as* „ is common kno»l«)t|^« slstors (FEW As shown in the within the Gigaohm tenge, in < o T m dSsr»s™' «< • out power l *«* 1 '"“|?,„S| meter. The numbor LEDs rather than a m ^ _ 0 f display corr of LEDs illuminated m th tftfTe amplifier. A bar sponds to the ou '?“' “J, a dded to eoy power em w .« «* b voltage reference and an individual com Sder. The in^t bu«.^dnv^i $ . on divider The parators referenced ° er p0 ints (the le power indication at *e c W light ) of each md, at which a particular « ircu it diagram, vidual LED is shown .in »•« ^ dire ctlv from Th e input signal to the cl ... that j s , in parallel the output of th ® P°^ e [ {ed into pin 5 °? the ’ to the loudspeaker. It ■* f neW ork R1 and ^ SSSfirll-V * rSupling ^ss^ssrjtsssti it limited bV Oil •« m 1/ ISO mA «" *J b „, th , bar type 1/ "■.SSI— - 7-26 — elektor july/august 1981 !%*5SS,‘5S5s ,2V transformer is conn***” ^ increase the supply 3 A voltage converter 's ® deliver the rated voltage so that the ampl ^r ca ^ include , output. (The converter may transformer). MOSFET makes theth.ra The advent of the favourable. The simplicity °< simple to co"* u Xr," " of ', w0 possible appn«»~"' possibility especially from the circuit diagram in the car - f^cpETs are a 50 Watt booster and design is very appa entire converter is s-iaswKt.-"-'- power MOSFETs in the car a. .« « conductor M *"° t w h t,h power equipment *or use rrrSAK ystsssr. « i”"" i" ’ respectively. intended for use in vehicles A booster empldier following requirements. , 0 ’SSSSEt ™bi.n. background no.se (engine, wind etc). „ be compact without 1 Sn,nTA ^in rr «, u^er 12 V simple swinging poster nncter' circuit was published The original 'swinging poste d is intended Jn the January 1981 disco etc. As the «rs=£r^s’rs'S;: K , „'.ll,”fo«nVout' of simpler version has bee d 9 cted from the ~SE *■ - that the circuit can be p olaktor july/august 1981 - 7-27 ^mfwm M ode 06 The bridge rectifier, d , the more -4“ ss «- ■— «? The heart of the <*™t »„ <* *“"% The 'zero-crossing detector * zero-crossing Si - siSt0r ^ t 7 age -3 POsUive pul* «• hijh. T '*"’S 0 ' I, brUete - Vi. ss^tysirs-i^-^ ft?SEt*®-tt , a’aS3S • m a plastic box. ks« — ■ six hour timer s^3r«AVis;;t d .i?Srb £ "S' JS °"V “rn'helSSm Ih.re- have no effect on thea ^ unti , the reset button music lovers who dritt o about the cost or Chairs no longer need to v h switching unit S «f"'S’oS.Sh o. «-*» » ™“" “r^othSaPPlirafio"*”"’ 1 .', jmo CMOS , T S'SS“Thn ; in,“ S ^ < ,“r, 4; <«. ssSv °< «* ^fe^sss^ssss (about '"O"’ 1 - “ '** 7-28 - dak tor july/auguit 1981 sssnsa 1 instead. 27 VOX for PA systems »„ annoying <’’?2‘ , " or ” , £v.r A doe*“ > f** 1 b ** tendency to wh"J number of me, ^, he phenomena. There a obvious being the avoiding the kers in relation to g XSSZZZ*** no, «-» - I it to orovide an answer ?C?r^S^ efeedb8CkaPPear ; U^S'lVnown that 'ampler by tween the microphone and^he^ ^ situations about 5 Hz will ,eduCe fa ,, St a -frequency shifter elektor july/auguit 1981 - 7-29 hat been included m Mhed out W "■’■““h.rS.n M Soned ■'^jfSSS* * "" V J“ IS « ^ P " ”“r',°'c,r« uS » control . -•« « JS. and « "“• 532‘Ssstl Xd to WO further opeTO*. * 2 ol PA . ampldten !■ -'■'VrS.h'.'t with diode D1. d uf *‘„, toothed out by “'■’“^.“h.n.h. W*» similar device. Thit Du variable power 'resistor . . foctina powe * difficuKV =#=3SS S?S2SS2« s,W"S';«jv- s -r^ 1 - mm. eov fhe^e voltage lot * «-? S^TS- via 3 SS'3 can be used. ^“^keep the battery as a driver transistor n ° rder * sible . SH^ r ri;r. Est“".-^r«rr s =3 battery. 7-30 - alektor july/august 1981 29 heidle auto reminder . .. vehicles are The headlights in ® This means that it w unaffected by the '9 n bon * ad ights on after t u is possible to >7*'^ Sees, this is also true « leaving the car. In many car ra dios etc.. > of auxiliary equipment, wch ^ batterv . * “which have been wired something of a n For the forgetful drive 1 , th cgr the following nuisance when trying to *«” as a warni ng to the morning. This circuit 1 something switched on driver that there « *t unacceptab | e amount of I which is consuming u , ved w ith a bit of power. The Problem can^ ^ , (s more obvl0 us logical th,nk, " 9 | ' ittle digital technology? than to apply a ''™ e 9 t loo ks a lot more compli At first 9lance. the circu ^ requires three ICs. cated than it actually equipment to be The switched supply £ diodes D1 - - 04_»or monitored are , w , 0 , *, ignition switch more if desired), the ' bat tery leads are is connected to 0/ connected to '+12 V and V. the ignition Let us first see t here are no power switch is turned on ^and on. EffectWe | y . nothing consuming ignition switch is turned seems to happen. citor C2. the output of N1 on .FF1 is reset w ^ capa«t 0 Qf FF1 , 0 w. As goes low taking the 00 sitive-going pulses, the this flipflop onW e r f o a !, a nd via N5. N6 and N3. the q output remains low and. that transis- buzzer. switch is turned off. the output When the '9 n,b0 " S ^2 will be set via capacitor C3. of N1 goes high and frz , of this flipflop will therefore go high 1 The Q output of this tup v ’ . FF1 receives a I to enable N3. However ^0^ ^ the data (D) I clock pulse via R3. the ™ of equ ipment on I input is low as there are 0 > ^ they were. The I S! SSiSStf output of N4 remains low and I circuits arc Ji. the »n» « that pre- I turned on the en , he ignition switch d I viously described. st ar t to happen! Flip- I turned off, howe«.t. „„ R3 a. before. I HOP Ff ' 12“ put is high, the O output I This time, as the d ® P c5 is charged up via I will also go h ' gh .^f^ciently charged (charge I resistor R7 and wh f N5 wi ,| g0 low. This I JJT l 1 'diStfa^by C4/R3 to provide a 1 further clock pulse for FF ^ charging , the dr iver still I During the pe™** * a * urn Q ff the relative equip- I has the opportunity ing signal from being 1 > ment. thus preventing the warmn^g^^^ Qf ppl 1 sounded. If this t c(ock pulse and C5 I will again go low at e The ou tput 0 f N5 goes I . will discharge via R8an • ina , condition. If. on I e low thereby resuming th 9 t$ tQ swltch off I , r the other hand t d Ng wi „ go high when | :h certain items the Z^n. takes the other input of | re Ss 'high 3 (N3 was ; ®"£d d p reJfo n usW) ^ 'that the N1 RIO over a period of abo , QW T his pulse is As time the output of 9 Q prov ide a reset pulse 1» f NS ."d O'O. On- -*<■ ° U ’ PU ‘ s r F nW°r»uTrrs ^'. » the It is possible, of course ' The circuit also switching th. i»»™ ““ deliberately ImW » -s 1SZSZ Sf.W - elektor july/august 1981 -7-31 ,„ r „ wjndW t ^s mmrnm disabled and transistor T1 ^ ^ clock input* f F T^«.”^eOU,p U <. r,™ , n , ».»™ M5 N8 90 through their adjustable square-wave mk»£«£ 3§ iss .““v j-srstxs- this The circuit makes use change state 'f a Schmitt trigger 9^*" reac hes a certain until the voltage level on^ vjgger thres hold. critical point known input, capacitor Cl zx ss ^ - ksskSU :« ?ppwi««« i :",r,'D2 h .n^’ reaches the ww ' •„ discharge via u uc S. as „2„; that this <««>“" “H" tsu cowoi =f '■sjtsswm- *» t3 conductance, thus ^ The detector is vr.r^o.« l irs55^5 , foc.o S »"»« “"“fSl s/N - 10dB): 1 1» (AM mod. 30*. frequency range ^wi mi 7 MHz . tuning capacitor. '*** • • „*«» some The term *•«*'• .^fiiffeobtein** bv '"***£' ^ explanation It ,s the , 9 jd 0 , a signal 9* ner *«' t» Due to i K,^'.5Lrr.p^o m * oo, vt. * «- ov * SS.' 7tt”o sss 1 ®. in AM "» M '"“5 t 5 low* » .r d«pon®"9 on ton w ,„p,o,en«>« <*" s sr w &« iso of 6 “ ss^sssssan RF core W 6 ™**} Th 0 .8 mm enamelled wq^ in. JWr^'sisr^ 53 & ^55 , n««.n."f'““o- a ”- elektor july/august 1981 - 7-36 S*f.T. 34 ! digital keyboard | following fun< ?;° n ' re tllocated a binary number maximum of 64 in theform of 6 b^t iittMsss n i . . Q6 and Q° can .„ rnat ; ve |y, they can De processor system, W U e converter an requires a single contact ^ r ke f V oUoWS; Each key * The circuit operation ** x 8 matn x. This sr-£ ,s d ® t 1C3 an d eight input Imesto contact r^SAS - - and when this key • tf^SSSsser- £ , B * 7-36 - atoktor jufy/aupm 1861 input buffers for the logic anaiyser The fnztJ ™' « «"*• analyser (EleK .. .. "JS- input . "» k ” “ to 'analyse' CMOS circmt^ hened thereby e n- _ the input leads ca 1 t0 be operated more abling the logic analyser easily- . lttt of a very fast comparator Each buffer trigger- The hysteresis (710) connected as a ^ by the values of the of such a buffer is d « terrn .^ n) an d the value of two input ,es ' rtors (33kft). Using the given the feedback resistor l f requ j re d, this values the hysteresis is around the feedback value can be altered- » wa lue is reduced^ resistor is increased, the ny ls0 depend on <* «, ™|T ° a. tli Wa- tt. position of switch = Mic 2 V « .oltag.s are about IV 5 V CMOS l«* corresponding to TTL on ^ va , ues are deter the switch set i" SSssk- R66.R67 - 470 O R58 * 68 n PI . 500 O adjustable Capacitors: SwiMlV ’-^/levtantaal r c r C ^710,. LM 710,8.^a,can> D1 - DUS minad b, th. io C»s 3S5.*4SS » w » h “ sppplv v0 '” l! " the buffers are shown m , '9 u * essary in order to S\™n oi tt» w mount it close to th. vertically- analyser, the resistors are mou connect rSb of nbbon . ;„d.»i»d the buffers to the Ribbon cable can in the articles ^^“^uffers to the circuit also be used to connect cable, however , under test. N^^hi^o cm which means that the s-asrr-i-i »b,.. — ,b. elektor july/augurt 1981 — 7-37 3 O ^ buffers, should be about « ^r supply '»,»>«', £ p”«u« -J S.IIV • '«» r *“ r “ & heavy. The amount Howe**. ® p „ith those of Current is * ~ „ the logic analyser is to be use v3?jg&&5& hsreassrrArsSs J^rn'or.’ , « °;^„S rSfrJs case, potentiometer P2ca2 b i e ^ »S V^^TpUSSer ^ an inexpensive ., , e the circuit as a h oscilloscope. , application for . th ® p?„e, potentiometer" ■ ™ J. iho „ed (mother ztrjszsr* » azxjsr.x n < the circuit ovc universal measuring amplifier , one of the more u hv now. one of the more An analogue ±£l ^ by elec tron,« ■standard' -terns of equ.P a( multimet ers . are & now f§g§ g|gi S ,1 ttf- -bids o*s T Su •“" ”5 ? ™” 'discrete disadvantages. T-’lL'^micted around transistors differential amphhe current jut* T1 and T Z. « . h hot h emitter .ear”; „ is possioie IW — .-- . provide th^s'potentiornewr »«h a calibrated sc.,.- 7-38 — elektor july/auguit 1981 37 digital sinewave oscillator An assortment of digiUl * of E , e ktor have Wnd «.» in W veer’s Sa— magatine over the years, c , r cui. de- SS i^ssrarrs less serves its P ur P° se v f sections, each of which ”™usdul application. on its «“j“j osc’dator “^"^"““tWee Scult constrocted ° ou?d”t«o ordinary fliP"o^ m ^ , non-inverting verting gates had been , a mn-inve. ting gate can be haup been required - as a connected in made up from two inverti 99 tQ cons truct r<,x °» - d ™“" 3W ” oscillator. follows Let us assume that. The circuit « k “K.J1 is low. This means initially, the input of ™ p ” 0 b , low and the out that the output of N1 »™ * . c , will then be put of N2 will be high- C>f»mto ^ charged via resistor R2. Km oi and the whole | input of N1 will 90 h ' 9 * V ' R ders interested in procedure will be to the National this type of oscillator are No AN-118, Semiconductor App ^f rcu[ren t CMOS data book, which is included in their { tw0 flipflops The divide-byThr.e section „ ds , „ would which both divide by two divide by £ expected that “ * ” (N » has been four. However. anot ^ e '^ X 0 f FF2 and the input included between tl* output cloc k input of F F 1 . This e « ert, ^ lt of FF2 changes polarity, signal each time tf« outP“t f the If N3 was not presei . en d of the flipflop 7° u k ' d n r ^d C with the addition ° f . N3 'j£® current clock P en °° . d the positive-going edge dock signal f. e.™ half period. * triggers the ."S' three. no. four, fore, the dividing factor n ..Tj-Ln-rmr 1 - 4013 4070 The sinewave signal VheTthfinput to both re- 1 sistors (R3 andR4).Wh e ^re JJ be no output I sistors is low (logic zero) resistors is high I supply (high! level. m athematicallv. | OWiousW. this can b, pro r ^ M but a simpler i"« h “fj° d i 9ra mmatic.lly. A small a single sinewave period a 9 g of the sine- rectangle may »* *™J ic 0 J e level. Two further wave to represent a logic be drawn to rectangles of the «■"» * area ins ide the sinewave each side of the 3 be half that of the of the last two.rectangle^ion ^ generates first. The digital h above. a signal with the same areas a, » noted When constructing the circuit 110.013 ■ that CMOS inputs should neve ^ EXQR chip In other words. P 1 " 5 ’^ ground (0 V) . M ,N4) should be connected to gr elektor july/august 1981 - 7-3: 38 transformerless aerial amplifier The omega-antenna, pulJJJ* fu , fil | e d a popu ar issue of Elektor however, the difficulty demand. It's mam e d ^? he broadband transformers t0 obtain the »-e ^ me up with a version prompted our design *“ partlC ular components. that does not require™* ^ n anle nna The -alternative arn .P l,f mme r circuits issue, was described in th ® P re fp ° direction finding purposes m rt^OMHz-g e.The comprom,e. although not mention® * jb|e tQ a , te r one of the high noise figure- P obtain the best poss- The re amplif ier shown * * tff jS«SS3SI«^ con- this requirement Althoght^g^ # somewhat 3?"-“ ,h *" '" oun ‘‘“‘ CT ssrss^-s: ysrasf ss-* the complex nature o t ^ -, t should be .b*™* Of » mainW »»» * pose a problem. 39 supply battery timer . „Knnt 1 2 V,T2 will th> volt«l« «™“ r?rnw?| S switchotf T1 and there; switch off. This in curre nt now flowin9 'T t fore the suppW- Th ® ° t u r0U qh both transistors but be the leakage curre {ew n ano amps at most, this will only am ° unt b the battery supply «'« To all intents and purposes, be switched off. to amps. A look at the circuit 'switcTsTis the many component: s i ire , supplies a base drive W button and when Pre^PP T1 whic h w.U current to the darling* 3 w the equipment in then conduct to supp'V ^ a)so swltch 0 n to act as ri^“ss™“ i ™“ ,n, *' ,b “ T c! P , c «o,c 1 w:»pp».<-» Me ' i ‘ B4 ' m " rendous formula. 1 • 2 , tr.1 in Farads). -59 • 10 4 • Cl • In ij R t = -22 l u UB method may transistors. 7-40 - elektor july/august 1981 „ W e regulator 1C. It will ‘JJ'ElEi ,,om »»*»» “ " ,his ~r£s power stabiliser ^ ui,=ui,=oo»t.o'.>>'’“.r. The ^buffer transistor has current rating. , ink used is sufficiently '**«- P*”" Provided the heatsink usea b ffer uansls tor 4700 (iF- of a three-pin T3SJTSIi*SE? , ic capable of delivering a “"'Sreeds about 200 wK *7 up ” voltage regulator Jutput voltage. , A lest) “'“‘“"A' 1 ?, ©— 5 'f° © — /c constant current LED a LED as a panel Ed Oteir 'operating PJJJTb wS* "Jgj ^Tn; i ,r F .°.dWe..b.brigb."--'’ h * L will follow «* K^D^vCa" “'“S »J^£aSK5S, . r SlSrcurren’oapabiidV »< ' LE ° “ elektor july/august 1981 - 7-41 optimum •“.Tio SESnS T ’ » ;■'£ "S i«« of T2 »«' '^0“ ® “ ,„ current :Ss£«5Sssrt- _ . 15 V -22rnA 5 V-l5mA i« V — 24 mA g V - 1 8 mA 2 4v _ 27 mA 12 V -20 mA ** 42 Kansas City demodulator , ccic (frequency -shut BJW»r s^’^s’asiS-T^K V (1200 Hz ana l900 Hz whilst frequencies \ freque ncv of '"W . Qb . level generates * logic high »vei. 240 ° H Sor 9 eve% Viator there has to be demodulator. circult diagramthe^ma 5 I A2 is configured as a w» (QW or high logic I the incoming frequency nto ^ ^ , QW pass filter -.^3£sr.sr ^sss the input IPSO eta™ 1 u °* whether or not ^ thfi s yst e m. ;?r«9S 'ontein. four ^*^1. Shtlv unu“ I in *>> '» «££ £ WP? ?’ Sut currono rathe. «t«n "'.^ orto „ amplifier device is commonly call«d » first Schmitt s^lfSrSS “,i the output of « J,i„d from A' . • point • posItitre-soms fuM ” we non-inverting S curVent pul« wii flo«in» that an mput of « s ?«ou,h the inking identical current must P . equilibrium. This input for the circuit o which is therefore > a ™! T„il. P. •“ocTmor.. The mo,. » 0 p ” u K',. , .Kp“"'> h ' W >„T A3 »n,e”ntion.l * Circuit around “.^over frequency of the fl't* r > low pass filter. The turn ve ^ inco ming signal. s' «« ^rsrrss£“ I -SSWSfS.- 7-42 - elektor july/augurt 1981 .. j_ * n ho processed .dges end '» ‘K ret»on the around A*. ™* " »“S CMOS 1C. « «•*“ „« sufficient W *>> “ " t the connection. “’^“Sntsnyvb.™"^,, „ only . t.» Current con.unrptron of m f a ” P w*.".Sy P " *“ and four cycles of1200 Hz. 43 signal iniactor - tracer * signal *,««« must '“^“^SuSnS rricSy »^?vs*a£? , «' ■ «£» Ttadnwlt very simple and S* * ‘JrwS main parts; a s ! 9n ®’ The signal aenerator. ( IC2) ' and a tT ' ain am ^ ac a 1 kHz oscillator. Wit ic3 i. » 555 con".«.d ^ oontinu.ty - .c nP are in series with tester. Since the ° t he circuit will onW ,h, oscillator. » C ”^ t ,„„i,y Sw^wjwkss-k iSSnfSl b. beard » <« <«■*“ «* W I'™ « »«™' Q.'potenticnneter .»! l detect change, in amplitude, it m elektor july/august 1981 - 7-43 wrt ,„ t not ,o switched attenuator Drov ide three different a high impedance input . by , c2 and fed via The P ^a* to PI vTch is used to adjust the input feveUo the ’preW^ visua , output indiOjion ■snrrssff used as shown in figure t. Because of the high saefned’^ad and probe rAisrfK sa * ,- " m ’^ i&gSvss*** 1 * signal output. 44i solar powered pocket torch *«*. ».«• ar r,« rS great *awb.ck. »t tM^™ tMtefore to mak. sSSi powc-l-ED “H ts s‘S“ rtfs «js£ scs^-’^rr; I The LED is driven by < wo S !^ at ^|y S 2000 mA/VI) extremely high slope UPProxirMteW- Q 4 v of th e SJ" *“S? *“ I for the LED. , pi This poten- The circuit is balancedbymean ^ an oP - clouds are present. (|i> 7fOO V 0. rO* 7-44 - dak tor july/auautt 1981 45 american billiards 1 §=%1s§?#3 ®si#i3w£s5 ?JS&«S§£5§ As soon as thre colour has . sSBsSSs elektor july/augutt 1981 - 7-45 the ffipf'°P s - . lltton si will supply a P u,s *.‘ h Operating the hit I b *“ out puts which are high JS*» flipl W*; ,he tlipHops that «»£ Will then. «» ,he relevant LEO goes "“i™ not already set, of the f lipf lop to «• sfr^ainS . v ,a s«*p n =a”» counter leads s0 desired, thiscen “ diagram hv the opy node sv 0 , the triangle, then be mounted halt»ay 10 .n hetween two red ones. 404 g which ir»^tr»^re, m .n. deciding »hioh 'J up g ,„,?her variations. aw will be possible to thinK P become familiar- wmrnm on. When the g^^V dr, cells. " be suff icient to use two CMOS ultrasonic Remote control of “pppidar' toth W» coming more and mo™ P f „„ be either a outside the l»* ™ '™„„d and the =&£; sst&tx&SxSA or ultrasonic remote c° n h art icle describes °or this or that purpo^ Ra^er. a very simple and ne I* of applications. In which can be used for y* a | on g time on addition, it jl'PSasth. current consumption an ordinary 9 v battery 140 kHz) from Toko ’ w to modify the input ImDioyed. it may be "«“ S “2 or T ” This transistor stage to the field e,,ect ' r ® if * er for the receiver. The foM^^threJ SiSH^sSaSHa used- ,ja . , piac. of .d-ipme"' W.o«l m OP." l- "'d “ft.n ' be obtained « A suitable «nW«*J , irms and, considering ■surplus' from ma ^ quoting one their low cost, it is na at home. 7-46 - elektor july/auguit 1981 47 constant pulse width oscillator _ j ran sometimes give Switching oscillators on and o th , or last to problems " “ '“"width from maximum (or both) pulses can vary ' rnost cases it is down to almost non-existen narrow pulse or probably true to say r t» p ,pbl.ms. It ■” ■spike' will be the °c e “ hi . osci Hator switch off fES™ iib” ^iHiiSrSoSS 55 anything. How"". „„ m the w»rt»m IC1 ,4 Oo- 3 auu«= o/BNThe variation in pulse n in fi9ure 2 (S/' T The last pu lse in the width is readily -W^,tSsmallfor»jn«IIJ»| second set may prove systern can. The to 'see' while otners . chase, could be an extensive red h« ng^ , f lhow r , m An effective solution ' ^ simple gate oscil- Z dm.lt in llgu-e '* ,™ p . Diode D. pm la, or is coupled to •" « hjr v during the time wents capacitor Cl fram This ensures that r«°pu« a° '“ output ha. «• — *»“ those foi'exihS' ™Vi i ,r“S'.s , my"'»d | ' l “ '"jjj rSn;i:;r,h°m.«s'con, tan. pulse widthoscillator can provide. 48 single 1C siren Circuit, that produce °lde““AP0ssible be highly popuw ”® c ”„,ct Circuit opera«°" ” i physical sense. ■ * *“ rnn ‘ a physical sense. simple and easy to ^“^t'iStlScsmgte from' National SemiconducBrs. _TI ^C.meL M 38 8 This 1C contains elektor july/auguit 1981 - 7-47 „, w NP together w,u ' , --®, transistors T1 .0^2 ^ ’“‘’.We Sbr T i.i*.» T »^,¥ris^.o.^ between 1 and J \ > so configured as a P £1 ■ 49 pulse generator H with variable duty-cycle ^—"“S’sisss.s^s diodes, a capacitor and ® £ duce a n oscillator with four gates can be U d M a vari able duty-cycle. The pul* a set frequency and a . RC t -,me-constant ot duration is *W™»J ^“*0, Cl •"<‘,.sMor. the network consist" 1 ? " h potentiometer R1 +P1. When the ^ 1 syr £netrical square- the mid P«Xn. d * ™ ^ iSTS wave signal is ° bt °' ne ° ered> , he capacitor (Cl) will the setting of PI IS harqe than to discharge, take a different time to cha g sooner t . result, 9.« ^rSnrd^ndin.on.b.dir.c.mnin *o— p G>“" 81602 2 „„ „ s rot,tad.™sa««t»•'*"'' i ‘'’ S, ''* , r" 9» “nr, >«"“ “C rf „’“'d'p C Ss"< on tit. ?n, frequency of t» ^ RC ton a of capacitor CM"®, ^ »*,*»*" 7av switch “"•S'S'Teolac. Cl t,..f.9om2- : S the 000.0, however, the mpu e , f the control input is . iro.?h.to«"s“pp'VS c „T,put pp>» “ "“5 r^.fsarit'Tfsi: t^ti^ 9 output! The second gate will then a , inverter. 7-48 - efektor july/august 1981 50 differential switch jsaiiSi'Jf'SnSrSsiJ triSty - anc * of e "f ?L.chU able to measure the S. The «w« " WO PO'"» "J; sw sue. » -js-^trs s* H - ffstsfey-j sr ra m=s%m Of the unit can both be ^ Moreover the ,l.u do not affect ea therefore the sistent results. A 0 f when the relay circuit to give •» ■ m335s £*,£««. -ytpJTKiS w”o« Wation.l S*"’ i “" d " C ” dtod« whose ”'"’f 0 om fS^^iarrsas SS®*^33£ • v ,o adiust the other ^sr'o* oo^ 1 ^i“d“T : cS»»^ re-sSrs^s & --■-“■sa r ?c -« 1 ° P inomV P 1 corf.sponds to about JO % ‘°. c , effect PI can warmer than Z 2 SSS'-*5rS?lS2S“S maximum factor hysteresis of 2.5 C. oosition the circuit has a V 5°C, the relay ence in temperature is o wlt h an operating led 02 should W a v re The supp iy voltage tor the voltage of about '2 bv , M vtdts because »W X^’/ooV, allowed to d,OT« ssss^S' 21 1 ,nd 22, if a thermometer is n elektor july/auguit 1981 - 7-49 51 hrens ■ remote control potentiometer . it possible to regulate This type ° f contro1 ^of'a^igh^sou' ce^ ^ the Oi i Sffi. » - S WSSWSs ' JSSS 25 A.^SSTSSS • tiometers (PI «"J «» * the input rang. «J opamps 0 A1 Ze a n od A2 is 0 V “^e^loS ' When the Went protection ^'J^J^eters is altered, the potential the^orrespOTchng oparnp. r2/C2 becomes «m»2* “£ £tp“' *"»'* SS 2JJ35S ^ ' ““ir, R 3“ R6 sr “.sr&?5 -rs »S.. »- t £» • “■srSw” ^ »" » ,h ' ou p Sv « sbe buffer A3. de»bere«lY potentiometers at tne Djodes 02 ana w S. of ibe «»”rfi“|SoO do«. "»< “ are included so that the P transltlo n. ssgssis i i=ssi=r e get the hang oMt the circuit are ratne 5 ’p^SSS?"-^- 7-50 - elektor july/augutt 1981 variable 2V. . • 60V power supply . • SGS-Ates is The L146 type ‘"“^^n'improled'versioh of the pin compatible rnllt maior diftar.m* well known 723 w •»' £ r typ , „ drfhwjjv between this new 1C ar ) supply voltage that the an advantage The i m»ur ^ maximum input 723 will handle IS w v , voltage to th ® ^ ‘external transistor or two it is possible* to c ° nstru ^ ha a t ^n^be S'ateTbeween U.rhtomATnd I bon the validity of specify 9 ^ (hen emphasise '» SVo™”..ra » the »»« — R4,R5=^ 2S12/2 W R6 = 1k5 R7 = 5k6 r 8= i n/s w PI * 10 k tin P2 - 22 k lin P3 - 1 k preset “;^™300t.TIPt« IC1 - L146 Miscellaneous: Trl = 50 V/1 A transformer FI = 630 mA fuse value. Potentiometer P2 «* voltage level w,thin ^ t0 set the maximum (high voltage end). elektor july/augu*t 1981 - 7-51 -a- a-™—. on s ssafa — due " 2 - ? ^rtnrr^ sr r^=s * bprSSvWS.SorhAS.nOC, AO* - ■ ltuiut elektor july/august 1981 - 7 53 novel flashing l'»9 ht . this circuit * vo, « ~ represent. oo •» “ £* ? h ” diagram shows f.». gating • »' L b E , D „,„d«0 to a used, by orn '”'"®a *ED a corresponding output r^=r»aSrrr.a= s -swjss*. ~ rase of a model of a r0 ,.„ hprsw hicb light up one use those yellow « arn, ^ u J ra tion at © shows how after the other. The mu a nYrema.n l j the LEDs can be made " 9 diode between each sequence by of the diode is connoted output atage. The oothoo is connected to the to the base of T1 ana connected between b=.-^jsH : Sssr'^ simple arrangement is qu the desired effect . t0 . an d-f ro' fashion can be LEDs whir* W i®.'" ,h, baaas of the transistors obtained by connem'"®® following manner . The „ the outputs of ™ oonneoted to the base oathod. of the lint *“ d c0 „ ne0 „d to pin 3 of the 0 « T1 and the anode d to the base of > *• the other to is connw:ted t0 to pins 7 ano • pin 10. „ *r.tallv ‘random By altering the ^ "^Sned. Remember that display sequenoe wn^ used the rese t connection if more outputs a t unuse d output. must be moved to the combined: all sorts ot iSHK 222=3 rr,a°S» £, that « ““'’pat'^tS 1 „, pr IC2 The outputs Ot I The previous pXu.. r* !?r;r& resistor - - “eD Dl light. UP). .^sponsible for limibng the and series resistors of* selecting a lower sS.- s sr;;Sts 3130*0. the 3140 is recommended. T5-BCS47B 7-54 - elektor july/august 1981 U ^ ^ 56 ’Hi-fi’ siren The title ^ • • d r« K’l'jsi.tss «- t ass^ :ss • going tell blest. „ approaches! M Wh." happens wh ‘" lifEr, faintly. The no'* first the siren is o V nroment it passes this is accomplished e d ^2 constitute the 'on Sheeted around M , «.!«.<* Srlcted a around *'° w '£ that the current '^ ^in f act switched on and off J°V T6 U a P nd T T7 SfftSi ° f *" d ° Ub ' e ^ transistors T6 J- J7Jn *. \ (N1/N2), which in ettect P 1 ^current, and rEEfS'eS™™” increase gradually duet ’ th voltage reaches the I C 4 At a certain moment t that th e flipflop I negative trigger thresho d o N . high . At this I is reset and the on the emitter of TB I - r, ss fessi’rsJS; lowering of the no.sel e *® nsist ors T2 and T3 ensures 1 The circuitry f ou . n ver y slowly at first, but I that the noise level ncreases vj ^ ^ sound n, 0 re I i ^i^i^rar^E^ « 1 K C«”r,.£S“ ntil fh. *« . as possible. , the Hi-fi siren is given r- ^tRUjss: l°P « 07 o if a louder siren is rep considerably, of h alektor jufy/ august 1981 - 7-56 57 low-noise microphone pre-ampl*« ier thusiasts are often ,ac ^ "'^ jjj Sect they ng able to get near eno “9 . uch a case lies , record. The 0 ise pre amplifier 19 a ®^ ,cr ^^ent^are ,ed with a . 9 °®° ua , y recording equipment are iplifiers in the usual ec ^ purp0S e. and JSSTSE S-- ^,7»S recording ‘^plitiCion of thB^J * 100 vards, due to t however is intende rtsr ‘S “"v/T- « ■ "Siss £•;.-< * ■ ■.•ss.'ssr . • yr S5S-3 1. 2s£ S* - - R10 = 220 k R12.Bt5-t00k R13 = 100 O pi * 1 M pre*' Capacitors: Cl- 1 m/16 V C2 - 68 n MKM Miscellaneous: 7-56 - elektor july/august 1981 7 dB when » «"**« !j A further method ol ® to a minimum. This curr.nl throu 3 h the the 1 .5 m* is in fad d °™ "S i, even W Wan the 2 "* (stereo) J h “ regulator IC1. “ ! required by the »>«• ", voltage for the included ft "*® “Kr po«f amplifier stages t sianal-to-noise ratio at t tion produces a high ' 9 ic distortion. Local cost of considerable ha o R25) feedback Of 60 mV, IS about 0J3 mV, c ,rcuit , mo unts frequency response o P 5kHz the upper limit 3 dB points, is 20 Hz t 0 f capacitor C12. being determined 1 by th they are The effect of ' interference from local included only to /li consists of a couple of turns radio stations. Coil U c {errite bead, and can be of copper wire through a omitted when there is no like.yhood of radio interference. imnrovernent in signal-to-noise nightingale'^songjrom a ^stance of J ^husiast can With the aid of * ,s ? ® ^ outs ide recordings of make music record ^ng ^ mi crophone and really amaz,n ? m q ent will naturally contribute JSft SSS. -‘Sl^P.nd.nt nn ft. | A, the gain of «" STS rin tJ» altered by value «f ntiluTfof this rasistot.How.y«t, selecting a d)"""*"*?!?, vo lt.ge of transistor strictly speaking, the cohect^i pf ? 5 v Effectively. T7 needs “ ha(e be altered A the value of R26 * ans a larger value for R26. smaller value for t|)00ld have i a value of For a gain of • , R2R should be 680 kJl. , f o k«: and the value of B26 s ^ L1 , the . By incorporating a «««» d bu , t he same > input impedance can changing the values of ; ■rs.v trs-s-'-sLTK: : i generated by the transistors. 58 extended range milli-voltmeter A multimeter, a. the. (j ,« Km. purpose measuring tool. »ft°“ a 6 , s „ r i„g AC in the For example. Its , [""Adequate, and the sensitivity, eudioband is usually ot the internal resistance and frM J „ , n „,„ment cheaper mo.mg-co.l rnul” P Th , „ de . normally leaves d“'' e " he „ doses that gap rang, millivoltmet.r The instrument in a very simple and e g . Rating current of flssssaw-"* elektor july/august 1981 - 7-57 oTthe'OOliR meter. ,„„ u ,ement ■»» The opamp level of B6 with *» ""T.io" m rt in a linear fashion. , id 0 f PI and the mm* T 5rr»3riS ssr x-rBsrJSZZ °< «* “" 1 “*”°" ,oW ' srss-Si* ,o "5i »v iTSfiSt* »“ very low. flashing bottle The reason for «• ""““m sh^of'the mmmm associated components which it has • carbon rod >"d aMtipCT Uy lmm e,sed m of our readers. 7-58 - elektor july/auguft 1981 60 : temperature alarm "■ ■ , „u or i, of a maxi- TO. design ■ ll »” s = mum of «“' ,e ™S?S' control unit by •»< ant connected >« the ” th , detectors regbters a pair of wires. When o ^ ra ture, an alarm an abnormally high or, ° W [esist £ Rio determines sounds. The posihon™ of ! registered whether the alarm is a t eset temperature causing transistor 1 1 the temperature sound. This occurs , h ntC resistor (B9) rises the resistance of the n higher than creases taking the ^ '^.wise). This in turn ^sroSSeU^low. „ RIO is pleeed »‘™“" “X t I C2 "d ground, the reverse happen*^ ( „i„,nc. I «.ni » *%’S a : inSVU.' of R9 increases taking invert jng input. Con I more negative than th ° will go high I Suently. the output of th^op ^ ^ flow I and a current of apP ° in causes transistor I ss- dm, » *" d 1 ,he alarm oscillator. of about Itt 1 TO «“ i "*'°'f.d .o the Pieto-electric bu.»' I®; , I which is then fed to tn o chosen to suit 1 This relatively high feed ™ v |, IO elements and I the resonant '''S^reWtat to the aural sense I because it is optima. 1 tivitv curve. . th _ maximum numoei ■ As mentioned !»«'?“* used is four. If any 1 of detector 9 ,rc ^'! l * I *he quiescent current would 1 more were included the q , d the design I exceed that of the alarm cum, the I e wou.d not ’ unct ' 0 n n “ b r e r Tncreased as in that case I . _ „ith detrimental resuttd jrf |C2 a „d its ; If another form of a arm omi „ed and the a associated »™”"3\ 0 “cont,ol a relay or °>f“ j transistor can be us t of the circuit, in other o similar device. Thesensrt ^ deu , ce operates, ’t «n rd be h adiu«e P d by means » use a ; — -7 can be obtained. include a simple fire Applications for the desg lw0 aquariums alarm, the temperature wrvtro^ and a minimum StoTandTt-perature regulator for centra heating installations. A f* v a hu ®© W 3“ 4a "4\ "fl elektor july/auguit 1981 - 7-59 61 voltage ^® 9 para?tel meters ere JSkSJdSS' £*£»*' tance »M can te “““ r , d with .voltmeter. The s^^rrss«d « <** i, h ^* 3 p-“» s “ wre9 “'* ,ors ' WK C2 and C3. i«yx series of voltage regulators " 5 S's=SHieS| SSSs"sS 33 f-| rs’-r-s^-- ,he o * ,r 62 EPROM light sequencer ther“oTel024 itself It is P° ss,ble f' EPROM programming 3 if Vou have access to an ^ epR0M which device. Otherwise you “ “ computer. This m rt-ov w» » ■»> m ,te will cause the eight 7-60 - eiektof july/august 1981 „ A test With the monitor o. W—J * ^ pu «, .hOW.d *» » program of the Jumu TO oscillator *«'?%“" of th. <*«* of potentiometer PI- IC5, which counts SnS»» *w. —V »“;“;J C TO outputs of up from zero to 10 " - ts Q f the EPROM i c ci^r»“ «*"» '°“ ,on * therefore read °^p w iU ' t ur n the corresponding output of the EPRO f transist0 r and nresent for about 300 (is at . . d bv the circuitry S— ■ ™? TlS TPu. « th. b... around N1 . _ N3 - high at this part'cula of t» transistor is »“° 1 », , u m on and moment, th. of the halt-cycle. fast TTL interface tti iCs are asked to It is surprising ^^“"impossible) task. It is of perform a difficult '* th gt experimenters have course, gratifying to k w^ ^^,^,,5 0 f the TTL so much conf ' d * the other hand, why drive the logic family- But, on « not likely to sur- devices to extremes when W 0 , this , VP e of vl ve? More often than no : ^ mistake nly. to 1C is overloaded, or th y latter case, the drive CMOS ICs d.rertW. ■ ,n * output voltage guaranteed active pul -uP CMOS input (2.4 V) is lower t^n the ^ pitching (3.5 V). voltage required to . gu ^ cMQS , Cs 1S essen- Also, the input imped* 1 ° that the slew rate of tially capacitive, which mea frequencies, the TTL ou*P*^i?"* b ^ , p^t09raph The upper trace m « ^ itive , Y loaded (220 P when a TTL output P” jve ^ oing edges of the in this instance)- The neg TT L outputs can "goal are still J 'source'. However •sink' more current than th y ^ at the same rate the output currentw.ll be^ the » s 1 — £5* VS Jj3o* - . loupi has reached approxim- switch until th. ‘"I” 'Tuntoths manuf.ctu.er ■W, ha» 'h' measures to ..old this. M a^ar^ptimum ^^^gffshown, an effort has In the case of the low® s 9 -^e-going edge by signal, but at the expense .J tQ - inc0 rporate a The Ideal solution, dllti „ th , positxe- VFET which will only °P The middle signal going section of th •— no» be ,te “!™ shows that the amphtu e the poslt ive-go.ng r.P.d.V despite « — follows: V/div. deal deflection - 2 V . orizontal deflectioi 2 V/div. . _ too ns/div (in other wor*^ 74L-S04 elektor july/august 1981 - 7-61 stereo level controls Supply voltage IstaDii SuppW current Input voltage Output voltage Input impedance Outputimpedanc* Hz an fflM Hz and 10 kHz! Max 30 mA Typ25mVRMS Max. 100 mV RMS 100 k« 100 n .... r notentiometers are used TCA5500 1C, a miniature whic h does not n be constructed very reasonable tt~~gszssr£«-*~ tronic attenuators, ®ac The requ i r ed voltages Balance control _68to+12dB Volume control Min 48 dB Channel separation Distortion II kHz an . Typ 0,1% 100 mV output voltage) TvP 70dB Signal to no * s ?'?; 1 P , and P2 »i*P*S* *^ is the balance contr °l/ Channel. P* controls the >m „,itic a «ion » f w 5„i„, the ampliMH™ volume, ana n mmmm amplification. the inputs and outputs : ssSsSwr" 7-62 - eiektor july /august 1981 68 Ae , as an extension to the This circuit is intended as a pub)ished the aSi-ss ' s^a - *• “ a ” ib rr 9 "« p»v°; ssr-ssi sis. s?w: r £ rs Ss c^^rSK^ type LO W! been placed m series L g D nDto-coupler na . now turns on, t . StfSSsSBStf rss«p*- » ‘'^r^ «r s «-« L s ■>' *”• " HSrSgHsSSS eT 0 " ffl P N4i *®f° i “ 3 m > 4, T 148 ^ ^ ' i _^ t X resistor R1 «l>» ^ a ,«» brief perM «■»?*’ >“ M »*» the mains waveform. Th m pr0 vided, of m elsktor july/august 1981 — 7-63 L. Witkam 6 bit keyboard encoder This keyboard "fwOsIcT^e h»r< p lexer IO.IIC1 "J, “ u l tiplexer. '« W“> “S IC1 functions as the 1QO i v voltage via resistor Sneered I to . "A by IC2. Be»e» The demultiplexer inputs «! >!“■ the eight outputs of lUt anu matrix There KUx^n^lanasoonuptoX; and Y . The control inputs (A. B This counter is ou..y»--^“rsfs h nrs'*- of N1 go high to p , c „u ,he output of N1 w W*! 'IhlorS'pe'iod of time taken tor W* mC2 to discharge via res'Stor"^ be , we e n The SSlS the *«S ssjs » rs^m TeX * after the output or • tength ot the strobe pulse. 7-64 - elektor july/augutt 1981 '“'^transmitter ? 0 ^ described here The The item . or article is carried arou " d hand t£gs, wallets etc.) con- hPtween you and your pos- __ as the distance between Y jnforrns you frequency end . frequency was cho w H p able compromise the t^ shortw ave and VHf 42 MHz, which is u* cells. , -namelled copp® 68 ,or9et 'Tecei°vVr • , a TRF design and The ■forget-me-not' receive' « 0 , a (cascode) could hardly be “"P 1 ® J^ctor, a Schmitt trigger mtMfMs m=SBSS be turned on. e.,.«v slektor july/augutt 1981 -7-65 I ^ . 4 The above procedure is obtained. This uoltaoe out of the diode ■ ensure that optimum alia ' ransmitter output is acss^^ ,procedu : r^d-^ r^aocvo^^-r" | ■ input H °< th ® S?£ a r^ximum reading on wi , hout the centre tap. < ^ to be some I 2 Tune the transmitter to between the )oop anten nas are used. u can also t* caused 1 ■ 5L™*J «?«» - M,e “ “ v **£g £££*«“ in 1 roS*ani-.~ U plin9.«.»- AO humidifier 1 and newly ““ Jt #1 w* >»>« 9W""£ Z . .e’i.bl. <’ V,' 9I J ™wly taken e“<«» Kftf. Ss-sr IT'S ° »•= £ - n XZSSSttZ r srss ss «*£, sssasas s i w,r^t5„ A : P ir ,,Me '“7;j t I out the solenoid is agai w electr , c | ea f that P r ° ■ tor xi which in turn tr'99 ... , t o exceed s©ss«**- I any metallic contacts and w^r« A new gU- l effects of electrolyse and^ ^ ^ hazards of ' I system which IS not 1 j s t o the transpiration 0 > I Sr. Y« IdW therefore be .. 1 requirements of the P« 7-66 — elaktor july/augutt 1981 calculated for ■ '^chT.edabS cycle-", cood spray of »■“ “„„ol unit forjrjj* r sr •jxj&iSZ* pW. etc ™ actual «alu« "£i £"5? ««». water plant bearing in in nd that = a a ecu, con'd coil of the solenoid yW ^Pn Th . yalue of « V ST'S** bufshould be able to pa» required amount of tm™"; rf aW ctl V to tbe mains, Since the circuit » 0 , regime switch, it is essential that t ™" lano id va |„ e be correctly ,h.on/otf switch and >he» a M fitted jn • waterproof plastic »» «» the tads should 1 bT fed outthrtutgh a waterproof connector on the base of the unit. >p ,rimental watering The circuit lends itselt to .. u 1S particularly »»"» '»«££■ X th." advantage sy.«m. in that *"■ ^ suttabtaggimes can be selected. 70 M.A. Prms . automatic soldenncj W, all know that Hi. “ouVof'tM off th. soldering TO" ■ < V™ ^ R „ house with other *S, I heap of smoking rubble. results are not usually » jjjgj he "circuit ] can expect is abl ® bl out an d will repay the here will iron the problem ^ effort of making it m J , C1 ls an oscillator The circuit operates ■* ™ a tim e interval of divided by 2 r > e*«* J?" R ” the end of this time about a quarter h “„„ .quads. Unless SI » ICl' r'e-starts the 15 minute period. ^c- tars swrc supply line wl " ca V must have an extra contact to _-tj‘ pole of St , »> bridge «. con..«-«»“^, p „sh The switching can be d simultaneously, switches which must bep"» <0 | t „, other 'tha'n'Kyoi'rth"" "^JffJSoSVSpPW «* kept between 3 and io v elektor july/august 1981 - 7-67 71 10mA • ’fSt:::*-. woiA...'*”* 10(*A 100 mA R.Storn • constant current •hat the electronics en- cation. « '* i^'g^ejnstir*) powat supply whenever be connected to a • required, a constant current sou '^ anot her useful application. tier or similar 0'rcuit. own , mains po»« S;S'“a . ^ .o«.«i-p.o30 4 iomA. • ,uu s=i=si?s ifisiifs give an ontpnt «W j| "*“ ,„„gtr load ^v^«r^^ du ".srirs S^3’?,’tSS«St 3 ."““simply , °™ from the formula' I ' RIO or Bit or BI2or Rl3 ^ ^ ^ 7-68 - eiektor july/auguit 1981 72 simp*® ASCII keyboard from an idea by 0. Hul 1 Many enthusiasts who 1 terminal for their (Jun » relatively high I from constructing one due reason we I price of ASCII keyboards. hO ernat)ves . present a design for one of the ch P ^ circui t an I for such a W 'th J ^ be obta ,ned I 8-bit data output ana I sirs ^“Sr^sss-'rs , i£ 1 first depressed y Tbis se ts up the I switches ls2 cn ' S6 H p nreS sed The key-strobe thus pushbutton S9 '‘JJJ^for the computer Wjs-ssffnLjji-as •“•©•^==£*55 ^SJSW5-»i““- 73 hydro-alarm “rsiCoome lt is well known that P“™ in order to pro- •collection’ have to watering of plants dice successful results. The wa an(j Mn become time consuming it ^ of the domestic “ bv ■ISS^iJSS'.Aw'. S3SJ The two electrodes ^ 0 rm the 'hydro switch . Ire placed in the «H> t and for, mt ^ p b t he &Tr~gs&J s Js& is rectified by diodes th is gate forms the of N4 to be taken oW o Sin«w , wel on this input basis of another oscillato, whe n the water will prevent it frorn . do "5. e nd of the © P' obe level drops lower l| t ^ a " iab bv R9 . The N4 bicillator pin 13 will be PoHed h gh b V buzzer indicating will now produceanoutputto ^ buzzer tone can that the plant requi * * h 50 0 k preset. be varied by ad,ustr^nts°f|to inthepotbut elektor july/august 1981 - 7-69 mmmm I si must be pres caches the ena bv raising the value of C8. tairly long life. . not critical and may The suppW voltage ™ volts However, if * Wi automatic reset ; sa aaaggs. □ whloh »«' S?' M tt» *" u~ -- For a clear earning mdicat ^ fQ[ the rest . It LEDs for D1 different colour lownffj r *• volt.,. I...'- v _ M LI0 The power supply for ft is rs* t0 aqe is then adiusted Potentiometer PI 2T5S S adjusted so that t Wj > and DIO light up the calibration procedure ° forrnar , ce ot Srfo.r^h-S'SSr.mumh.... tolerance of 5%. o O 76 word recogniser and delayed trigger Many oscill ° SC -??. eS JJJ ,1* regularly displaying digital signa is. gnough w disp |ay, but „WI«ind<»i tl»*r' W^ ul f0 , both analogue This extension circuit ot t he circuit is and digital s'9 nals - J h « h f ch P can be extended if an 8 bit word recognise^v ^ determine the trigger "” m e ' om di ' ,er '"' design and an; •!» M “ *“ le ™hich has SS'Sffl I— »< E " k “'- ” consist, of «» J““JJ “™ poSXto oWf reP te with pins 2. 3 or H m ro' U '“ ,C Ob.K” « "0”“' «' 1 " PU ’ its «iii.i»^'“>“s , ’ion.«. °< «• The timebase de .'* v MMV1 and MM V 2. The monostable JSLttlbie over approximate V actual time delay is a ) ^ osci „ oscop e and is, the same range as , ti mebase. If required, therefore, a true sec be rep | a ced by multi- 1 potentiometers PI a a c)ear SC ale marking. > position rotary switches c)earer indication of the s This would pmvi^ a ^ . con j u nction with / timebase settings. jWher possib | e to display ’ ■ the word reco f '^ ; lta |^aveform as required. The e anv portion of a digit I dua , channel logic S al Th. d ’>nolMue hiw' "^f^'ch'only have an when used with oscillosc P ^ additl0n of the Vis au tomatic trigger cwfJJVy, t0 display portions he timebase delay makes t require deta ,led and ’as 0 f the analogue *9"®* " t han would otherwise be It more accurate axammat'O would t* the top of the case. A couple of examp a squar ewave to a sinewave signal f/J^'Tor 'bounce' etc. examine the amount of Utter o 7-72 - elaktor july/august 1981 V-/ v ” 77 humidity sensor slightly modif ied circuit- ^ slightly so ss-i-jvss ;?™S * supp ' v SJ& S, do., opt "» pobh.h.d in « °o .hang. th. gold. When th. • SSS? ” first ic W. »f c 7Vh, other mold.*”*”* Si”nJ .nd th. S”*nd C 2 C6 and is twd “ tr.quencv f *\S*£ SUSSfE 5tX^ ™. SIS. i^lIJmS^h’ciaciuno. drops. This implies that th d {ference in time •ttS'TS- sK„'“ v1 ' tt . adjusted by altering / p capacitor and 'Sr-iSs*- - Sfa’S'-H"; 1 m? - After mounting the C 4 is turned capacitance due to 9 “ dicated correctly, until a known humidity capacitors with prated by •“i"'* 1 "" ” wjh ■>"«»■ F “ (a very low and a v V f or the high one SST for™M>win. fez&s* * £*uS. or. of conrsar “"““'SVotimpad.".. So he conn.ct.d . pro.'d d «* ,„ alo , u . nn i> '?>“.%*' « “ “ ^KSr Sin » “""“r„o U ih,T“.3 R4 » «* ™ s at the common point o ^ — — <3 •Mctor july/auguit 1981 - 7-73 Resistors. R1 ,R2 - 470 k 2% C4 - 3 ... 40 P trimmer C6 - 68 P C6-22PP1°° C8- 10^/16 Vte n, » lum C9 ■ 100 P CIO - 10" Semiconductors: IC1.IC2-HEF4001B 0?-BA221 11N4148) M „od«W « such. ' “' ,M .collar “r». . a PCSS to .«»nd the ^“VSrlch ££'?£ .«" > «• *« “W * 1 B7 78 crystal : oscillator. . • * ...for Ipw voltage supplies a crystal oscillator using It is very easy to construct a “y jr ci ,cuit oper- a field effect tranustOT. Tltis ^ 15v olts ate. at rel.tl.ely lo» J » g,„o, laboratory upwards, and was tested cryst als with fre- rftt. cortirtton-or-gardetiduartz ^ , quencies ranging '™" ' “ JSe„ the drain and gate The crystal is< OTO-wlW*" ' op e„tes m the of the field effect transistor . inc | u ded to parallel resonance mode. Coil imp rose the M»OT~ls»«* , s additional tW , application and the series 'padding 0 P® h tsO 0 phase shift is tances of tne ret • transistor T2. circuit was tested with In the laboratory. thl * al ' 100 k Hz, 1 MHz, 4 MHz, following range of The circuit can be used 6 MHz, 8 ”a“n, due to It. Id* •«'* in a variety ofaPP v minimum). voltage requirements |i. ^ 7-74 - elektor july /august 1981 6 to 12 volt converter .... anrl , \ j\i u Beetles and E5 s radio as they require o h ra te a 6 to_i4 v 10 7 V. One solution IS ibed here. This simple converter of TOO " A a " d c..P - >"* These two characteristic wh ich contains two from the concept of t plifier s and does no integrated audio power w amplifier. 1C] . "Ini lire a transformer. The w* - b tor . The load and maximally nd amplifier. lC2 - Sl When the output 'he * dded ,o that aero* the oppoait. Ph*J h „ d low ,ia the 0"gj 1 the output of IC1 again 9° be c harged and the ,C2 goes htfi. TJ» ' ^^rMsed. Capacitor JKSflSS- “ ,1a diode D3. fina , aftect of the <»!! n ‘.".c-fs V lead-acid battery with a n mi ith S*;' 2 V pSoeed ao outpu.vo fo tW> "> * *» °o load »nne«ed w ' .*? * I c Steo. of «0 1mA, "° to 12 V. At an average c 14 V. These „ average vole™ » v, '“* ?rX"< »" ""n P dC.Sw = ' l0 ' d ' sumption when wjjjjj'ja, , n additional limiter the converter is P r0V,de ° v zener diode and a com stage consisting of a ' 0 , (transistors T1 and plementary Darlington cjrcu' maxirnum yoUage T2). This ar;angement t l.ma me capacto C8 ”ooSd to the »o ^rTandoS Of ttJSatpot voltage to leaedtm*”, no effect °oad conditions. °odn3 P' con ,erter on the o, th , £*£» ° „o, iced, quality of radio reoep is shown The printed circuit boari <« ’ smic tion of the mica washers! on a c heatsink should e as 9TdM.ee> to the PdfTTiCantplifiersoo"®" S‘7,h, ™»*- ? a3M'SS K- s^ssstfrsa*- BD 1 3B/1 38/1 40 2 = TOA 2002/TOA 2003 *03 - 1NB401/1N4001 BC547B Capacitors: C1.C3.C7 = 100 n C2 » 100 p/1 6 V C4,C5 = 1000 p/16 v C6 = 1000 p/25 V C8 = 220 p/16 V Semiconductors: T1 = BD 136/138/140 S^D^WWOt/lWOt S»- 15V/400 mW -er d.de |C1 ,iC2 = TDA 2002/TDA 2003 (1N5401) .™ rst 1 ■ss ufSiS - « * ,v ih “' d b ' a.— to higher output raised by about 100 im be conne cted in currents, two conv ( - irn -,ting stage (B5, C8, D , parallel. In thatca , second board and T1 and T2) is om^tedfrorn ^ wq posi , ive e , ec . connection made betw T1 can then be trodes of the two C6s. Transit bd236 bd2 38, one of the o fo ,,0 --9 WP - imum current BD204. BD288 wJJ^nSlng two converters that can be obtamedbycon 13 A , there- in ParaUe ' ^Itte “ad o' can be i" 518 '"* 6 fore stereo or cassette i<> cars quite easily . 7-76 - etoktor july/augurt 1981 12 V to 6 V converter . . n V car radio a n 1 2 V car radio “'"“mote'st and°rXst ""“wnf"®*" 5”»"» „ „ 5vo» i™®r„r«rs d “r.s :ts « *^ 7 /^. s- Depending on*» *{? a * be ^ een 6 of V the ®5£ S'So/->»r,“VT n S"-- 385 ? W --SJi *. w — •» 12V 7805 © £> T— (LM 309) 1 TSri touch-sensitive 16 channel multiplexer ■ described once -n.'ssssi^aw^^ S.nd ^-“^n«o;ding to « must be 'Ote rcori f 0 ut mputs ooe signal «*•**” signals is pas»<} V is a 4067 16 analogue input sign , c2 This ICisa** •^s^«s=» Parts lit &s£Z=?i3r% _. £■■•.&-- rja‘- channel selector. _ , h * the operation litt multi-turn preset potentiometers Capacitors: Cl ...C4-10P C5 - 56 n = 5b n . . . C22 - 100 n Semiconductors. .04 - LEO *" d ?! :::»-™» Hovsever. it should a'"" o« 1C3 ,3I40 elektor july/auguit 1981 - 7-77 „ a control signal for all ] it point E and can be used ^ nQted however. I ;orts of apphcat.onsjtsh Qne Q , the sixteen that the input ^' f.he supply voltage, inputs must never exceed ™ ^ control voltage If the circuit is ^ , he case, it is of a vari cap “ Sf is no t suff icient since most quite likelV * at12 v reau ire a higher maximum ssEWKSSr wsaw*" ^^■■•r3 d A , st--2 1 r The noteworthy p0 ' n . ° hanne ls is made directly, that the selection ®j* e ®*^ h is is accomplished by in binary code, by t ned - n a s i n gle 1C. IC1. using four flipflops a Rg kgep the inputs of the Pull-up resistors R1 • __ of t he touch contacts flipflop high a * l0 ”?. sC1 . C4 are included to are activated. Capac.torsC 1 ^ level „ the P~v'de a PO^ f «J >re indicated by LEDs outputs of the P in binary code. R/S types. cnikes This also manes «» by brief interference spikes a particular circuit easier to °J* ra * mb J r must be known and channel, the chann number m bjn bv also how to “"vert that nu , using the touch buttons.^ ^ se(ected . , then assume that channe bina ry cod e0101 (lt xsnzi z^ttjrsrs: buttons. ■ornnramming' may appear rather This methods of prog m 9^ ^ (he hang 0 f it. peculiar, but it is q advan tages: you get to Furthermore, it has d t he circuit is very learn the binary^ eight buttons and four . economic in that ^ this means can be - KS W *» ■ rtide «*"* , "* ,s g the 16 input controller. 1 7-78 - elektor july/augu*t 1981 u v-r ^ 82 dual input | channel selector % W . . -rticie is a different n; ■n» circuit dctcriW « components tt wQ buttons. TW» nthis S T" at* f •idt.S.pt «•: a*< - c sr-s» <°rs* * **« •» mo and transistor T1. I tf^s2?Jrsr-“= decoded W > « „„ of a**" 11 *' “"“digit.l I 1 ■ I ci cod. i. *«*“• °" ""“Jcoltict * ^S?55Si s ^S'*=SS S ^SSrr-^™ ss a issssr— MAN 6650 mjfll 6 V J? 1 IC2 I SN 29764 1 n n - 02 °r R QJ f — 1 r \- Crt t LH< elektor july/august 1981 -7-79 O V VJ 83 16 input channel selector This is the third method .?* “^his'issue^The first channel multiplexer described^ whjle th described a binary using just t wo touch- second J ¥ Now. finally, we come to each channel. It P° f the oper ator. It is method of ch ®"" e “Ses in the decimal system. S'WSSSji.’SSS Of the multiplexer. Weha e can ^ passed input signals, any ° ne . d use d to control L£Ti"«» w *• “™ IC “ as a demultiplexer. This device .is controlled SJtEl (4029), which, 10 ( brat or constructed around from the astable m ... tion 1S approximately N1. The frequency of binary code at the 500 Hz. At each c oc pu demented by one. This multivibrator constructed inputs are When one of thes ^ ding demultiplexer input is operated, the correspond ^ some moment m pulled to supply co ™ m ° unt from 1C1 . the signal time, depending on * uit . plexer , s passed on to from this input of the d m^P^ thgt m0 ment also the common output pi . " pu | se triggers the becomes logic z ® r0 - hicb in turn enables the monostable multivibrator. J h of the latch is " latch and the b ™ r * thii moment. th.re- i transferred to to the channel ’ fore, the bmary code P th# output * which has been operated retajned . When the button is ™'** S ' h d are operated S described ir^th^clual Input channel control article ,ed can not be used. 7-80 - elaktor july/august 1381 84 K. Hense m post office letter scales No doubt, “ S “ “<=“ »'*“ a ”" r “ d '"o d «t ™" » » the required postage c accomplished elec electronic scales t j, e latter were no mechanical counterpart. It t a letter on to case nobody would th.nK or w simple circuit is shown in f i iijure 1 - CO g S ‘*“ supp |y I SSd . ** sS' ™. « >r' a S from the battery ^ ^ re ason. the reg tZ S.n«i tVlSww indict. f»« d'«»'f ”' D “ i light op depend .« on LEDs. The relevant Ltu » » Qn t „ e reales .The UoTare «tll.red ^"^tio^"”” . .M '|e” r nd S en?-^“" LDR \ R3 0 ,, i ,h,..dl...-'iV.>.. • SEf&To? 53* "JlVfT Sitin’, 3 certain voltage will appear at^ this vo ltage is *• LEDi ” 0 " 60 ... 100 nTD4 100. - 150 0305 150.200 03 ... 06 over 60 postage s, class 2nd class of the scales. It consists of , few extra components F t re2 t«n e c X o P ^Z amount of lights elektor july/ august 1981 - 7-81 the positive aide of the power SUPP.V. the corre- sponding LED will l«9ht u P t Qf , he scales (see The mechanical construct. old . cann ed figure 2) is reminiscent of t go ^ (he ^ circuits' issue t Da “ mba is a n old beer or soft thing to use for this purpo** uired . The lid of drinks can. AcWa W. u) is removed and the first one (w.th the r 9 P we 1S also discarded. The b0 "° h| f wi || be used as the lid for removed (carefully) as jnder 0 f this can can the first one later on th wi „ just allow a also be thrown away. A hO h ^ ^ ballpoint pen to pa« »h g ^ IS , ( „ fac t. bottom of the -^'^ r h d e ed b C a lpoin , pen is then used upside-down). The can . Next . the 1 attached to the base th ted in the can w.th printed circuit d _ d space rs (see figures 2 and sufficiently long bolts a d P ed circui , board 3). The exact ° cat, °"°\ be tallpoint pen is pos- should be S lustration. Obviously, the tightened up. h the uED (D7), the It should now become cornb ine to form the 3 LDR and the point of the pe^ ^ thall he opto-coupler. At th ^ accura tely. The LED and/or the LUH ae pu ^ SQ tbat , t |ust *■**"*’ end of the ballpoint. holes in the side of the The next °P eral '°'\ the^LEDs, the switch (SI) and can to accommodate the L j orn eters can be the holes whereby the P- es e P the LEDs adjusted. It .s Pfobahlveas'e^ Conner together on a srnal1 P . then be made via a tions to the main board^ once soldered, can be length of ribbon cable, wh baMerY can be stuck to glued into place. The 9 double-sided the side of *e c " ^h . P ^ itioning 0 , the rnd V a a |rr. a ?or d .°"r=o m p'!e«<*. .h. »c„.s .r« '.PdV I for use. (or similar) should be The table shown ?rt^of the can next to the LEDs. attached to the outs.de of the required for the I so that the amount o p Qff ^mediately. I particular letter can ^ we || be taken round I Letters over 200 g may) « under 6 0 g can be I to the Post Office, while gre calibrated by csssasg I over 200 g. R3 = LDR 03 R4 = 47 R5 . R8 - 330 p1 P 4 = 250 k preset Capacitors: Cl -10 p/10 V tantalum C2 * 1 p/16 V tantalum Semiconductors: 01 =5V1/400mW zener di 02 = green LED 03 ... D6 = red LED 07 = yellow LED |C1 * 7805 IC2 = LM 324. CA 324 rcuit board and component layout 7-82 - atoktor july/augutt 1981 85 mains voltage across * * e described ' n cir< ^g U sue . to each other T^s ^ Circuits 979 ** a 7 ener diode in the circuit. ordinarv forward- | as a -^s-jssaS: switched on dotM» g”' |, d from .rising •»» through the i u abou t 20 mA * be about 4 mA. ana 470 n is chosen. 86: SSR3* i s5§g=ss= ■ iSgg#S££ K given some attention. is , loW . circuit shown, the active e e ava i\ab\e ln (virtually any °< J cerrectW)- noise duel Ft ' ' FE Ts should wo* crYS tal are eliminated by tne configuration. •:^*SSS%Z=~ ^ioosoecilWd"; ^ .Mold be ed- of Current P-W ' fllfti «. ■*-* E obtain the -^roTen ^on cot. tvPe enamelled copper wit. t*(V 12. f+t elektor july/august 1981 - 7-83 87 caravan connector tester on. .. the ™« '"XSXZSSSZX? coupling ■ »»•" “ correctly- Hopefully, van lights are ^'“^occasionally. °< course. everything wi II work. °u therefore, where something fails. T . h * q e Caravan or the car electrical does the fau'tlie." 1 intende d for checking the car system? This tester is intena the caravan conning pin. m when they should. Simply P}^ jKel{ is so simple and watch the l ^^ escrip tion. However, a word or that it requires no desc P ^ ^ amiss . Obvi- two about constructs system (positive ously, for cars with a positive eart a „ the side of the b ® Mer y,. C ° n " t 0 be turned around. The LEDs and diodes v»« » „ on ,he test plug I FDs etc. can be mounted as shown in the '"ustratioa rt the component* Some readers may P re,e ' t f fair | v long lead so in a small ,h * £ ,°hts etc. can be tested that the ind'^vSon real enthusiast among from the driving position, i n mou ntmg the our readers may ft 'slrument panel of the LEDs rZTE'Sr* the «* ket,) ' 0 If'l PDS car (wired to the b* ft ^ s0 t het the LEDs are vMbte in the rear-view mirror. Qf LEDs : lurrKr&i&M t fault, which, ideally, shcmld^e te 15 ^ bg prove n i trsis „ k-jsss standard' con D neC 'l° who ^re fortunate enough to colour code. g 8 0 onwards, will possibly own a caravan from late ly warnjng , ight supply find that 54 G is the r ^ 9 < ee d is taken via a and that the, caravan aux^ in t 0 the separate single P . 'international standard. ™-,„ socket -V« »"«»’• „ ell M cues system Unfortunately, there ““ , h0 „W be wired* but the meiorHV whet the wiring .hown III. riluyt know either. We c.n only numbers mean. «■ 'ayer.g. c» •s"™ *”J3r Goyemmen, deportments have blueprints wicn w ig48 referred to since about itw f 8 v“tow left-hand indicator* B £5 right-hand indicators 31 white earth 54 red brake lights I 88 universal digital meter ,1, digital meter is a! l'“$ »°"nc ,u ^ iflESsraSflirssss* «-£ circiid^dtams «-*»" . have a much lower ’Sfsi .«K™-=srre3« , typical leakage current o ^ ^ Th ™^?Jssrs^ SiS ? , s£ the left ot iv-h elektor july/augujt 1981 - 7-85 ,k.n e.eiy ° en . To display a the display should he ®"« '"^'Kah cas« the sample r. t. ^Sl iond. add the meter responds ,he universal digital meter ” a J ,j ! ,srhd F .!*£>'ed«^" m ^ of ml is ““TJJ S'fo’thntiredi'spw ™! P oy™rc 3 il.nmd S se ; ..d o . : dm.-!' r s siyTa'bout 3 J and aga,n ggJSi* s rejec- display reading back w known voltage of. tor 7-88 - elektor July /august 1981 *n = iok . R12,R13.R’ 5 “ 1K R 14 = 220 n P1,P2 * 25 k P3 = 47 k P4 = 10 k Capacitors: C1.C3.C4 “ 330 n C 2 - 1 00 n C5 - 270H Semiconductors: T1. . . T7 ” BC557 02 4V7°400 mW tener diode °C1..'C3-356 , C 4-CA3162E IC5-CA3161E IC V ’TdS = red FN0657 LD1 - L ° 3 green FN0637 yellow FND547 or: TIL 701 *** «Sf The power supply ™ * • tion . The zener diode is XT Important i»«« ,h. floating or feet that »= “" 5; „„de, the case of the lie somewhere between . operated in the fixed sts* « « r-sKjr ft* ss» ** » 89 high power motor controller Thu hi S h f»- W.oti ZNA19CN ^, r co nsump ; electric m0t ?n S 25 A.°T e he ic'incorporates a pulse- tion of up » wh|ch dnv es the moto ex1?nal output amplify- delivered by the srsss* $r* t Si sss elektor july /august 1981 — 7-87 setting), PI holds * [ The Son" *<&» whereby the r” “3, m on the signal « pm J of the motor is dep transistors T3 and T5 which, when 'mot., tons in . *«■£ to be switched off ana in t wo transistors direction. When Pjn * •* J Station is reversed via conduct, and the direct attention should the relav- When wiring th . otherwise the be VZZ r “to^dSnion. Th, £ motor could run in t . the ce ntre position components 9 Depending ^> n the ^“"oH^toVor 6 P^allei ^'baT (B7° f relatively high cu t dissipating at lea capacitors C6 to C8. 90 ring counter using timers The 558 quad l'»™'J;i“’^s l "*th'e'polse»itHh that are able to 9 ener ® le p ^ hours . The timers can ranging from . rn,c ^“ C °^hout the use of coupling be arranged in serie * f the last timer is cep.ci.n-S; When *• she M «- ««™ simple -3 “""i',,™ coon... by The advantage of p c | oc i<.oscillato- -s using is '“,M,S.dfodelDll have bean needed, A '"^ counter to stop or start " edded which e™ bl “ A logic 1 I- Mtf* response to . ' input w» >»P «« voltage) on the c « 0 will start it off- S.ThSw S»™ d <“ *• voill become logic' ^ Cl £•£•! « output S' ’»< a" ”°’So! 0 .h°. 9 «m«rs need no. necessarily signals wi* *<’•'!"' P “i| ch determine the periods resistors (R1 » ""o k ml 100 k. To obtain »«' , »C4 canb. — ■ (Philips application note) 7-88 - elektor july/augu$t 1981 K crystal tuning fork Th« musician. v«ho d “’ "a luisilHJ »“ will no doubt ’ Jtectronlc 440 Ha >oond S~25s5s2£2t5£ Ti^sSSsfatz* :"r5rtM.a--rs ^^*sSr.-i= : 5"£ ,he oscillator SS™ 1 „ t0 art 8 SI loudspeaker l* ?»°" * 6 d 'Sc“e«i.lt an asterisk. «uW MH> - & ! Q&Z 6 |®C elektor july/august 1981 - 7-89 Capacitors'. Cl ,C7 ,C8 = 1 00 n C2 - 330 P C3 - 33 p C4 - 68 P C 5 = 50 P trimmer C6 = 68n C9 - 10p/l6V Ik j volume Of the resultant ton. ^ £ » — * —■ ° r bv “ T! . w US. BF 199. BF 494 Form „t mil. Current eonsgmption T3-BCB41B l»»«'« d,romW I L »i„nof40.. 50mA s,-.»3s '«, s rrro' n po-« ST.’S!— St - single-pole switch pro.® > W'“l” „f t 0.05 Hi. This remains LS - 8/0.2 W loudspeaker maximum deviation than most mechanics considerably more prec " devices. 92 dynamic RAM power supply , t is Often a o°n»monjwj*J» aid of ranoe of a microprocessor sy Qn conS ider- economically priced different supply ation, the first point ' “ 0 , m.mor, dev.ee. voltages required by *“ £ raMs require supply Generally ?o "nd _5V. Unfortunately, voltages of +5 V . *12 V iupp | y ra||! „„ be it is not very co neerned. Most m.oro- foond inside the »">!>"“ , slng |, 5 volt supply processor »g« be How, therefore can obtained easily - . 0 f CO urse, is to replace Ih h e* .“."rrhsCsfoime, by on. -** he. three second.ry -sW3Hssa^ cheaper solution rs suggesteo figure 1. h so-called 'chopper . i ne The principle used s th known 555 timer 1C. heart of the design >s the*. multivibrator with an outprTt^'frequerrcV if 1.44 f = (R1 + 2R2) Cl •_ -a of the 555 timer sr=»ts# rsrss -i will therefore re ^ u,re .1 manner. This is ac- e smoothing in nd iC2 for the + 12 vo . ssrs* “.*33 srrjffi Sal. gap of 0.17mm. 7-90 - elektor july/auguit 1981 93 2 m transceivers *°^ T5T^““ •" f§f§i§§§ ^rssstn- -»— 1 L, - Ul . g symmetrical , 1S oci>t«d “Soutput impedances bandpass Alter. sh0 „,d b. no P>» b )«"; , r , both about “f Mo.™ » « » w ith matching. i” e d ^ n cppT It has a very tow dppb, balanced modulators instructed correctly. « Provided the circuit obt ain the following region 1) ... . < HR = 5 MHz bandwidth at 7 MHz ban J*'SS5 -40 dB = 22 MHz bandwidth at «u ^ . bandwidth at -40 on ^3»Ss=s5sS “art for construction. -i|W — r 73 •— "T it \ »fc 1 1 \\ >B !!r^n , 1 1 1 1 1 L 11 1 ll TlOOP 1 1 ♦" 1 1 • ««»’ etektor july/augurt 1981 - 7-91 bar graph driver . new integrated Philips have* ,e ^ e ' 1 "'( e , ' n lr specifically designed to circuit which h “ Slavs. The readout is^the control liquid crystal d W> V ds , , number of form ot a bar Staph, „„ , C is that t automatically after an interval of two seco s."5"s ^jrsssA srsaWsSj - 3S,^r:iln»r«,...M.h.™.w.nce.b^ arc berwaP Phe^V^b” J™ ,’„d"Sn lie 'anynyberet«hween s ^““always be required. The input buffer opamp maY jng tempe[ature value^ For example. v * ,e V?®l an d replaced bv a ' 10 tos-STr-s^-*'-" supply rail. . graph display with the humidity *"»' t0 ^ ’“.'Tv^uiut of the sensor circuit. 7-92 - elektor july/august 1981 95 microcompressor he used in snv D V „, m ic ran* " ds.ic. that ‘ ” coms to miod 1<" automatic “ord Mil »<£' ' h0 "”,' ssgassri ss : in combinBt-on ^results as both quiet and lou give amazingly 9 -gy intelligible- irfi4 e speech passages ar e equ J«V around the TD A 054 g The circuit itself ,s ®*' 9 « om SGS-Ates. This ( mul ,i : „„,pos. «J™, ,„ m „„ aacd ° , a aood compressor s words, not dy mmmB W4 tf,u u .' p . " when this rises above ^ sssss**. "*r T r. sss&r* «* -'-* 1 ** r>.r°° « *£ EiSSirir: i r. is. 1 **-” rjs^sSiKS ^1 9V.25mA elektor july/august 1981 -7-93 96 3 in 1 pencil holder There ere manv -J* «BZ SS&& iority of them tend to become ^ intended to while. The circuit *•» SSrtSna two other func- The e circuii°dia9ram ° f th ® f| ^ C onsiIts of^n re°adiW ure 1. The extension amphtie ^ >n integr ated available suction Tl'^ggj -j-he output of thjs 1C Ted .. an ™‘ h S d“dS h, 16384 in IC3 37 Hz. This signal '* “* y minutes. This I to provide an output pulse e ry^ ^ wrn drives output turns on ,, * n ““ T h's'secf,on is intended to *?;r. SrS about t„. month’s hi,h 'phone !Lch »p«”.- on or , he pen/ A suggestion for the m h ^ ^ 2 Svvltc hS1 can t ETSSS«*-"“*. pen is removed from the holder. 7-94 - elektor july/august 1981 s ” b six channel A/D converter ihei, menu usually » ,0, '* d ,OT ins “S words, temp«>»t“''^P , ev el, Before «»• are expressed a h processed, it needs information can Pe turt P t pat , compotes nan rraStr^stn.-^--' * i=„oi to a particular t0 convert the '"P^J^odulation). During the pulse duration 'P ulse J] t ine in the computer pro- Z&sspxszszz level being measured ^ (C1 are represented V The analogue data mp t ^ q< these inputs can the symbols II • • • l6 f .J loqic levels presented to £ selected by means o the log 16) This ,nfor- the select in P p u «‘ P {"om ihe data bus of the micro- -SSSit*-— capacitor C2 to be e h ^ After the e nd of the voltage plus a constant 0.7 ^ djscharge via , start pulse cap *'* ■ k ?Vhe software counter must alektor july/august 1981 - 7-95 I Capacitor Vi ho ctnnoed at this i nstant. dl counter must, of course M stoPP^^ ^ find of t he su Figure 2 shows that the tin « “ e capacitor discharge " trigger pulse and the start o . ^ d A constant curve can not be immediate y e" iod 0 nl V the P time. to. is contamed withm^h^Pure of the leve discharge time of C2 time period t 0 will of the input volta^. Since en ^ ^ input voltage still be present at pm 7 check the analogue of OV, the computer mu ‘ . Q v internally, input 10. This input »*****«£ C ° b le to calculate From this the compu . other words, the the length of the pen . ° ate the binary value compute, must » » “ subtract which corresponds to thP men t later on. it from the result ?» »" memory capacity To be able “ ma . k the data bus. the computer must I and the width of th he | arg est possible volt- contain informatioi measured This means that the age which can be mM s «' ° f d Fo r this reason, voltage level l'™«™ ‘ Vf‘" i, ornod to . an internal f“ lol 'i 1 3?£»!£oi«ll » «» reference voltage C lta ^. The computer mum permissible ““'nout and divide the binary must also examine this input „ this by value bf the discharge time ™ „„ counter can the highest h u ”“', “2, division is a time period reach. The result rftta div^ , „ is .hemfo.e t£ZZr~ *"“* * *• ” flow”. tcino 07) from the computer are The data inputs (DU • • • u divided into .““me dx external end the t«i sufficient for sa'ecbng the D . tvpe latch IC2 internal analogue channels v ^ measurement Input D7 controls the *■_ ^ $ignal also passes procedure via pin 3 ° connections to the through IC2. The rernaming w ^ the u.-state rtata bus are, in tact, r , .if its the following buffer, IC3. This latter ^ lf f[Qm the address task- During the enable P outpu t from pm ^ deader l A/D Se-d; W=J I. bu , The Of ICt is passed " wh ich was selected s *S,-S:SSr'»... | »i- — sns« «. ■™^-crbe d trd’.u- h decoder connections^ The combination with Qpnarate addresses, or, it useu . gt the sa me the read/write line, they can ogra m required address. iiceli microprocessor ; ^ d « “r r^ M .di r „ j* .-ss y mX? llode'is requ J e df a ° r °J verter can be used in "d S^^^K-lt^Se re phenomena, provided the mP However, , r above the value of the reference^ ^ ca , ibrated by if this does occur * V analogue signal is ,re means of a voltage dw.den It connected a s srso«-d c rcomp.o»«. 7-96 - elektor july/august 1981 98 W. Gscheidle - v SD eed controller for model boats o, cc... «« mrnmrn S‘i° , "o n dLr* ■», was The circuit is built round the it. to the decoder output o servo-driver ICl dir.cdo" o, «. *>* rS S£s=5=!x~ 3dS id *««?* »w«d »v ■ SITS* 3 activated end directton ceed forward. '■ Motions In th.ssrn. "■£ e .pe.d of th. "»toi S ootoot B IS >«» "V. puM «“? “ S : SrJSS.a=sr- r.rf elektor july/august 1981 - 7-97 m m TKi. is done by the pulse currents greater oower Darlingtons. should be rep'acedby po necessa , v is done with The only adjuitment that follows; with the trimmer potentiomete l op (neutral), the SmirpT should Z adjusted until the motor Stops. Resistors- R1 ,R9 - 1 k R2 = 1 k2 R3 = 8k2 R4.R6.R8 - 100 EH) R R23 3 R24,R27 - 22 k R1 1 .R20.R22 - 470 R12.R15-560 R13.R16.R18 - 4k7 R14.R17 =2k2 R19.R21 =680 R25 ■ 1 M R26 -10 k PI = 4k7 preset Capacitors. Cl = 22 u/6V3 tantalum C2 - 470 n/10V tantalum ScB- 21*2/10 V tantalum rs= iou/IOV tantalum g.M.,Vnov,— " Semiconductors- )C1 » SN 28654 IC2 » 4093 IC3.I04-TIL111 T1 J4 = BC 557 T2 - BC 547 T3 - BO 436 T5 = BO 435 T6 - BC 516 01 ,D2 ■ L60 D3.D4.07 - 1N4004 D5.D6 = 1N4148 should not be more than 2A. 99 H. Pietzko W active notch or CW filter , inw-rost shortwave In general, th. ' "gSU*. Usually, reception is ss* w • ns* 1 - . R.hi An add-on extra for the a very narrow bandwidthTA^ ^ erefore prove ve ry existing ioe.rOI"”', .* ,“„ c h> more expens.ee one -on-'-' *> parallel mode U-*™' ,°om llgur. 1- Tt- (notch fonottort ■>»" „„dlo output of the filter is connected to the re cord.r output. The ..clear or, it P;“"V“ "£nt to drive a i pair of ,s The “simulated 'inductor A V2 S around opamps A2 and . ^t signa l is provided by ■ ' 9 30 times. The mu Mn J s 'of ^potentiometer PI. 400 Hz by f^ 80 q ore set potentiometer vltchSI in P»«» iu>« P™' » ~w » oSwi™- This " h £ . a preset 'VP e » 8 Sd'TtS£» ^^"^issrs* « ’°" o ''' n, o „ ounced „»^orf««W*S"£ , S.PC0 »i*r a « W« w u “ e t l < h8 rec0, ' re i 100 automatic car aerial control SrJt^B*^J 3 s.v 5 ? ys ?. r !I j •^uun- operations. . , e Mlth modem elektor july/auguit 1981 — 7-99 . , in t he CO 4098 1C as multivibrators are ' W the aerial used here. One m ° n ° f '°. P '^tive-going pulse at pin up and is triggered V negative-going trigger 12. The other one requires a neg fun down . pulse at pin 5 when he aerial ^ fir$t The control pulses ‘ ™ R1 R2 , D1 and Cl to 'de bounced' by compw*"® ■ w|th an active convert it to 8 147 V The pulse duration for te logic high level of 4.7 V. 1 1 P the valu es of PI. VSSVXT- second by * RS and C3. The outputs * transistors „ , 0 , motor it disabled, which is just a concerned. d directly to the battery The relays are c ° nnect d , y fo r the monoflops is 101,0= •'motor control ®|p If is nuite sufficient to control In many instances, it is q * . Hovvever , ,f a motors with an on/ f 7e^uired, the circuit given more 'linear control s d ^ bjt magnitude here may prove useftJ • EX _oRed and fed to comparator (4063) mputs are^tg ^ Qutput vo , t age STS SK So b. derived, f. iosteooe, „.m A < B) can be used to polarity of the on or off and/0 h '° r * of DC motors. This kind supply voltage m the case or of circuitry can ^ antenna tuning or 8-00 - elate tor july/august 1981 f.tf 102 continuity tester o Thie includes s P ace easily into the hand. I, is possible tb“ it S"» * . of P-inteb *»» Jj'&Sw of tM eoPPe- .ho testinq much quicker k w jth two test circuit Ix°^ alternately causing a ^ u y of a few kHz. The across the buzzer, at a freq ^ indicates the tone produced oy connection. 1.5 V, The Circuit oper»«. use of the •"»“ Semiconductors: T1.T2 - BC 547 B BZ- buzzer PB-2720 (Toko) 2 test probes 1 .5 Volt battery olOlo elektor july/august 1981 - 8-01 as otherwise the tester 9 by placin g The tone will then indicate 9£ by putting a test must. naturally >* al ,o » useful f» « s,i " 9 The continuity tester the continuity of wiring. 103 frequency an 5e?ecto e r * frequency range over : ked loop * PL '-' adequate for use as , multiplier's n ° t ther efore. also detector The i circu . locking - when tive to frequency frequency are lility and behaves in a 4046PLL . The comparator (pm 13) 46 outpu t is differences being that the ... n_n-n-n- n - n .. rrruT-n-n-n ... mT-n-H-n-n . J-TJ-LTLTLn- 1 5l nnnrinr frequency and P h . ase aneous |y. Should the phase are both rese ' ^"n^ut signals alter, the reset shift between the two P“ bi f nstan ce, the average timing will ", one o, tha flipflops will voltage a, *• 5 ”^0*.... ThU '« d-** sr^-sTrSHss® Sfr^r'- C! 8-02 - elektor july/august 1981 104 .. uiln ro power failure forecaster This circuit t*". 1 ” StS?*. logic high level at its ouip Thjs tirne delay, supply disappears Sufficient to take emergency although short, can be su . the data contained ,h, circuit coM « “fj th Tis S »itv *'* . raw smoothed The circuit OP 6 ^* f f °^'int B and the raw supply voltage appears diodes D1 and unsmoothed voltage ^^en from figure 2 02 appears at point • p e low that at point yf ?? * 2-K moment 'in time transistor T1. « ld monostab |e transistor T2. turns ^ig^red. Since the pulse multivibrator will ^approximately 15 ms, TTLICs elektor july/august 1 981 — 8-03 elektor july/august 1981 UK-14 - elektor july/august 1 advertisement INTRODUCING- from Elektor sc/mputer m build your own microcomputer system Elektor publishers Ltd. This is the second in a series of books describing the construction and operation of a personal computer system that can be as large or as small as the constructor desires. An updated version of the monitor program (Elbug II) is introduced together with a number of expansion possibilities. By adding the Elekterminal (ASCII keyboard and video interface) to the system described in Book One the microcomputer becomes even more versatile. Book Two continues with a description of a BASIC interpreter (NIBL-E) and gives complete details of a basic microcomputer card which can be either incorporated into the system described in Book One or used separately. The final chapter of the book gives all the information required to enable the Elektor computer to be programmed in the BASIC language. ORDER TOUR COPY HOW Price - UK Price — Overseas surface mail .£4.00 inc. postage and packing .£4.20 inc. postage and packing When ordering please use the Order Card in this issue UK-16 - elektor july /august 1981 advertisement sc/mputer w 'music diqibook t ■ a pi.icItc.'U «BoduclK» 300 circuits JUNIOR COMPUTER BOOK 1 — for anyone wishing to become familiar with (micro)computers, this bookl gives the opportunity to build and program a personal computer at a very reasonable cost. Price - UK £4.25 Overseas £4.451 JUNIOR COMPUTER BOOK 2 — follows in a logical continuation of Bookl, and contains a detailed app-| raisal of the software. Three major programming tools, the monitor, an assembler and an editor, are dis-l cussed together with practical proposals for input output and peripherals. Price - UK £4.75 Overseas £4.95 300 CIRCUITS for the home constructor — 300 projects ranging from the basic to the very sophisticated. Price — UK £3.50 Overseas £3.70 DIGIBOOK - provides a simple step-by-step introduction to the basic theory and application of digital electronics and gives clear explanations of the fundamentals of digital circuitry, backed up by experiments designed to reinforce this newly acquired knowledge. Supplied with an experimenter's PCB. Price — UK £5.00 Overseas £5.20 FORMANT - complete constructional details of the Elektor Formant Synthesiser - comes with a FREE 1 cassette of sounds that the Formant is capable of producing together with advice on how to achieve them. Price — UK £4.50 Overseas £4.70 SC/MPUTER (1) — describes how to build and operate your own microprocessor system - the first book of a series — further books will show how the system may be extended to meet various requirements. Price - UK £3.70 Overseas £3.90 SC/MPUTER (2) - the second book in the series. An updated version of the monitor program (Elbug II) is introduced together with a number of expansion possibilities. By adding the Elekterminal to the system described in Book 1 the microcomputer becomes even more versatile. Price details on order card. BOOK 75 - a selection of some of the most interesting and popular construction projects that were! originally published in Elektor issues 1 to 8. Price — UK £3.50 Overseas £3.70| When ordering please use the Elektor Readers' Order Card in this issue (the above prices include p. & p.) • • •• For personal sennce visit one ol our stores Our new store at Hammersmith is conveniently situated near the end I of the M4 and the North and South Circular Roads. There is excellent street parking on meters a few steps away and Hammersmith Underground Station is nearby Call in and see us soon I incur • CATALOGUE • J20 pages packet) „„h % dab end pictures of ^ • 5.500 items • •...•* Over 100.000 copies sold already! Don't miss out on your copy On sale now in ail branches WHSmittfJp price El. In case ol difficulty check the coupon Below make it easy... •* **..«**• with miipyim • • A a m a _ a • Easy to build. • • w superb specification. 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