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jelektor decoder | PLEINTEP| É Das. Editor Wi. van der Horst Deputy editor Technical editors, Art editor Subscriptions NERO GER “Halo ir His vote ato à Corespundime number ef pula Digital displays are becoming quite popular — even though they sometimes consist of little a igor do ro more than numbers painted on a rotating amgar, be “voliage to puleetrair “co drum... This particular type of display is Uns pu mm cad beneath the dignity of the electronics enthusiast, | "nte pu aa of course, ea If one is to keep up with the Joneses — or, Rasa e better still, beat them to it! — now is the time to. iasca acenaiaico iodo install a digital thermometer in the living room. imistic tania neaase vias Preferably one using seven-segment LED sho ja of ot cas, ie displays. epi” oro, necomine” ineesiety popular. Adonai to 15 à sera tacy provido a cleariz Iegible Ts “emos desentbed Bona mercury pel Te tnpeiaturo 15 dsplayed is wie Tovenr, e a esta po matter to coneit let te Fabesanei temp Era Er am be connected to e die uni vi lmest amp legê The basic principle The ut const of three divina prupee ( a sdieao ode) ih some na “deconis. Th 5 aa Cotas cometer (Mio tie aiso lv ima the dind e lhe re oram tg form cuteat source. À reference vota 15 | oac Input (pia 5 ot 43) a cin a voltage, set wish P2, 1 applce to th Ie Fi 295º Klein te now posse to set PÉ so dat Goccina pau cone Voltage-to-pulsorain e OE polis, ro dh Mumboc sf o pag reset poli tom AS Too opang dated qt tmeatoni aero. A quis, 4 diterent steel vs Do se by opamps. The our sepes of Common. Te mese hat they mit eo Each mese eye poe proce as us. e mae Ea hs upa rum ÀS ecomos Te, cuiteni ous tarovet, R$ ama DA iso lhe aveline Japor Of A, causa 18 out ole DV. Tais ucpue use fr uti me AR Ena dia imedê ii fo and” 3 gre. bach Dloc Eron ogellaçor (A) à enalit Tu lies praduce. shoe tie Pubs St ecriisecond interalo, Tho e ie pule ca be se vt al rent lo ong RIO fo bc curto of the pulso. Gparap 7 Nesving into a capacitor for a fixcd Ala Lhe ouspue of A? sl ineeose ins serio Of step. ca ave Cu one Iva e e putpu roer A? is aoove de DC volaoe apylce to pat *A the Soltage às passe thenugh diode D? to lack Ie muinto hi vitae The ed A à ses o also appcas at the “He output de mais dt -pules Lire propor Lo Ae vols Dt ho 24 e Ti pose vn dspvod as temperature Pulse-rain-to-display iaogrstea Circuit type CIMUSO. for the papo, ami Le did e Daly oquios a siglo The tset pulse that stuets the couat do reset the counter (TC and 108), Ar ão same tune a Blake pule tuna o the play until ale ie cout Construction and adjustment “The desiga e matat al ctica, xo 12-16 — elektor december 1976 thermometer Parts list for figure 9 Resistors: R1=1809 R2,R9,R11 = 1k5 R3=4k7 R4=1k2 R5=19 R6,R7,R8 = 6k8 R10=18k R12...R17=100k R18 = 2k2 P1,P3=1 k (preset) P2=470 9 (preset) Capacitors C1,C2,C4 = 100 4/16 V 000 4/16 V =470p On Semiconductors: D1,D2 = 1N4001 15 V/1 W zener diode 1N4148 or TUN (see text) BC547B, BC107B BD135 BC109€ 1C1=723 (DIL) 1C2 = LM324 Sundries: F1 = 100 mA fuse, slow blow Tr1=9...12 V/700 mA trafo B1 = 40 V/400 mA bridge rectifier cooling fin for T2 8 the components can be mounted on the board without need for any special precautions. lf the whole unit, including the a temperature sensor, is built into a box, [| care must be taken to ensure that all components that get warm (trans- former, power supply and displays) are | kept well away from the sensor. | However, the sensor does not have to be mounted inside the box. For distances | up to one or two feet, twisted wires can be used for the connection; if the 7 | distance is greater, twin-core screened cable should be used as illustrated in figure 2. AB [| It is advisable to mount a contrast- RR RS o q cs o E Ca enhancing filter in front of the displays. In spite of its long name, this is nothing Ss E more than a small sheet of red plastic. To calibrate the unit, it is best to use a (cheap) multimeter. The procedure is then as follows: As vs bu e ma js aid expo RR E e "evieo Homer, rd 1 tgp prá fa Pl om lhe display board so lat à e ing ro shoulg nom he apo, “aotad the outside of the sobcao. This dseps crentine im lab an th unit ha far aum Sat. (ne dee e late ne SO aceonting tn ume of te poe deseied abr. nau ho valve DE CS jm the ADS ISUnor lida el 3. im lh mb púsion and 2 aitintt ty poa sé US tranca, Seis will he suitable; im some circuits Juwer ad ralues are also parmissible, rop ater el lan É em Boa a tn temperature for ence le ease” indie, Por Mi bes diconera ts he Mata ter (11 = SEDHSS) aa be install 8, re cialis om He pl, à or aaa emacs ama PL = renloeê by a 1 dn potamonm tod gi ne task anel RP change jo 230k 0 he Alba dosande, eith tg dee nor at à | DSi pes Fermi log th a censo» regue when dá ir dt drops ay or E unstable, fes a ip es og, de fe ed | ae a | Eetmdie Be “bri e fo to cone dao are nr je, an st Pê dn he dirty Elen rem let o a ieret setting 01 P3 amd tepeat ihe une prosedur avaiaide, check that lhe maxiaum temps aa cam e dipraves ee etuee 1058 Sud LES | a Dlgod Sr coast 1MÊ is oglave | van OE th ockeronie preto | che pinaimefor he BRA accordine lo E TO8 LE UR manimim temp | am Bo pat ama Mute saves or ek. | (he tica Pro ictuoa publication. | fire e vi ode er Se | fg, Ai a 2 mei fo à sea ao. | This has prved lo be mcotct th | Di 4 itrene seta of PÉ | Ireduces. The” Sennheiser. HN5S, | corre pining ssh de lista A me ie note puedo a | ui e alo apoie, vom ver | pago 1331 ni ee CNT r 4 fY| Although most readers of technical magazines will have had a surfeit of digital clocks by now, we feel that the design given here may still be * | of interest. The integrated circuit (Fairchild : | type 3817 D) is quite cheap, and it can be used as (snooze) alarm clock, radio alarm clock, stop- watch or time switch, to name a few possi- bilities. 2 All the components will fit on a single small ; | printed circuit board. ERA pes ? bao a lu qo Sei EE E y: Na O festss er escolgag no é BARRINE brita GLetti 4. Sehmita In most large towns and cities (for that matter, in many small ones as well!), the parking meter is a very familiar sight. Installed in both likely and unlikely places in an attempt to alleviate the problem of insufficient parking spaces and at the same time, as profitable (?) sideline, to raise a little money which can then be spent on more “no-parking' signs, the parking meter seems to be becoming à status symbol for progressive communities. If one is careful parking is still relatively cheap, but if one forgets to get back to the 'mechanical wonder" before it gets hungry again, one runs the risk of making a much larger donation to the city treasury. By letting you know when your time is just about up, the little unit described here can pay for itself in one go. o ndo o ao mins Sons of à aces of beep and Shtine LED. Th cre To oie pec common MOS sra ova TE Diante Ci is Sac the as DR epa dae Tri o do 1 rt (CAOS) Th fa ni ati 8 AR a 2 So cp 1. 000 3 pet | e These vutpuls are connected tu NAND Emis e | ase kid Bis and (he Chi input No de camasetod £ the Dinars 2º ut | e is ont oe Hi he a al ee eq He, the time ds aposon “condi, Ur 15 mimos ar pr ts e o pj a Mg, and since De] o o ado ba, ne uu E NI Sol Three te out 1 e] MA e a a “20% o a na Re “ e TM eia [a | pelacivle mes da cas Edi ampli cito G Senesnder 1925, 9. 10) he output stage compiaim . Ta RL a o Ec a “Found, rot between in end output E Senna sa laio E Ta eb cuco doe fel al lhe 11 Trâmsilors TIFT? foram amplfer B. The Toe sum é che volta dp arc e imo “estos Regula Ipe Irsholê solage Va oé one Cloé. 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Anybody sho Bus esa the soundo coma oue of asi xi goes amplos vt he qse otro ve lo es mi sou av oaorer sora!“ aparoac bas Tcady Desa tele da à low apple tia lh o resul Lion, Elos 18, October 1576, puge 1048) Literature d Quad compor tor eloá mou, mgort, Deiobar 1878, 8. 1048 Precio Bleironcs 6 1 Zaolben vm Zell, Chapuer 2, “Pipe Technos abra E Save this mamtts mailing iuragper in case you aver o ger Sava tis montrs mailing wrapper for vour next car. * Have you already DO 2 ron away this montra Have a look Vie regrr to inform you may be you Shar you vá inserestea in have to start digging she circuit through the waste arinted inside the wragpor, vapor... (Pleasa nal queries de partment does not make house calisto nelo you in ho seateh.1 There are two basic types of speed control for electric drills. The most common type simply reduces the power to the drill to obtain a lower speed; this has the disadvantage that the speed of the drill depends on the load. A more sophisticated type uses some form of feedback to hold the speed more or less constant at the required number of revs. The control described here is of the later type. It is suitable for most electric drills, no matter what their power rating is, although some minor modifi- cations will be required for really high-power drills. The existing motor. contado cure, he torque anos ih speed as shown figure L Tabs die ler ires from e mim “il Mereloce dido dot the curso to do este pesa tenibnl ande sá condi, some form of feeênu time el Cha). In ir mov, the] as must be Found to ater he verao alte Of am aheraina corar The Samba luta do Fome rei 
