I

DIG1TAL lC PROJECTS

by F.G. RAYER, T.Eng.(CEI), Assoc. IERE

BERNARD BABANl (publl~hing) LTD THEGRAMPJANS

SHEPHERDS BUSH ROA:O LONDON W6 7NF

ENGLAND

Although every earc has been uken with the r~tatioll of this book. the publisher> 01 author will not be hdd responsible in any vroy for any errors that mighr occur

~H98 l. BF.RNA RD BABANl (publishing) LT!)

!llut Published M•rclt 1981

.British Lihraiy Cataloguing in Publication Data Rayer, Fronci• George

Digital IC pIOjccts. I. Jn!Cl!)'•ted circuit$ - Amateurs' manwls {.Title 621. 381'. 73 TK 9965

ISBN 0 R5934 059 7

CONTENTS

Pai-• INTRODUCTIOK . . . . . ... .. . • . •.... .... . . ..... 1

CO~ONENTS . .................. .. • . .. . ... . 2 JCs and Holder$. . .. .. . . .................. 2 Alternative Numeral• . . . . . . • . . . . . . . . . . ..... 3

GN4 1\ixic .••....... • .. . .•......•....... 4 ?·Sector LEO$ . . . . . . . . . . . • . . . . . • • . . . . . .5

Other Com'pon"n ts • . . . . . . . . . . . . . . . '. . , . . . . . . . 7

POWER SUPPLIES .. .. . .. .. .. .. . .. .. .. . 9 Battery RUMing . . . . . . . • • . . . . . . . . . . . • . . • . 9 Transistor Regularioo . . . . • . . . ............ II AC Supply. . . . . . . . . . . . . . . . . . . . • . . . . . 12 IC Regulator. . . . . . . . . . . . . . .•.. ..... ...... 14 Nixie Surrly . . . . . . . . . . . . • . . .. .. .... . .• 15

~lultiplier for Nixie Supply . . . . . . . . . . . . . . . . 16

PROJECTS . . . . . . . . . • • . . . .....•....•..... 18 Nixie 1\umerator .... ._. . . . . . . . ..• .• . .. . .••. 18 1 ·6 Numerator . . . . . . . . . . . . . . . . . . . . . . . . . 20 "Steady lll!Jl<l" with Counter. . . . •.. ...•.. . . • .. 24 "Twinkle Tre•" •..• .•• . •.. ....•. .. ...• . .•. . 27 Roulette ........... . .......... , . . . . . . 29 Six-Spot . . . . • . . . . • . . . • . . . • . . . . • . . . 32 Koi$<JeS< Switch . . . . . . • . • . . . . . . . . • . . . . . 38 Testing BCD and Oecoder·Driver . . . . . . . . . . . . . 39 LEU Randoin Numerator . . .... . •. .. . . . . ...... 42 Scorer for Be:cique, Etc . . . . .. ..... . . ...... .... 46 Mulli-Disit Counter . . . . . . . . . . . . . . . . . . . . . . .. 54 lOX Dividers . . . . . . . . . • . . . • . . . . . . . • . . . .. 55 ~ta! Slop.Cock .. . .. .. . ................ 56 Quart, Stop-Clock . . . . . . . . . . . . . . . . . . . . . . . . 60 Response Time Indicator . . . . . . . . . . . . . . . . . . • . 67 S.>wl<l Initiated Timer .. . .. . • . . ........ , . . . . 68 Ugltt Operated C<:>u11ters .... .. . .. . . ...... . . ... 70 6·Digil Frequency C<:>unter . . . . . . . . . • . . . . • . . . . 73 Ui[!ital Signal Gene rotor . . . . . . . . • . . . . . . . . . . . . 81

!'age Radio Frequency Marker . . . • • . . . . . . . • . • .. 114 Variable 555 Pulser . . . . . . . . . . . . . . . . . . . . 88 !·Armed Bandit... . .. . , , . . .. .. . . ....... 8'1

INTRODUCTIO::\

Tllis hook COl\taiJ1s both simple •nd nl()re ad>"anced project'!. md ct is hoped lhal these will be found of 8feat help in devclopinj\ a knowledge of the workinp of digital circuits.

Variuus fonns of assembling •nd wiring the integroled citcuiU on their board~ are sltowu, and thls aspect of a ~roi•ct can be quite straightforward, and not need the preparation of a printed circuit board. Tlte more amhitinus project• c•n be built and te•tcd ucp by Uep, and this will avoid or correct faults which could otherwise be troublesome, and will result in o better understanding of how tlfe de•kes operate,

1

COMPONENTS

IQ tnd ROl.DERS

The in1egutcd circuils fit boards ur 0.lin .nutrix, and I Cs and their holde1:1 have the ~ame pin 'p..:ln(l', thcmgh the holden arc a liulc wider than dte ICs tlley carry. Actual holder design• vaJ)' ~omewh1:1.t.

Pin l may be indicated by a n<1tch, dtprestlon, dot, number I, or ridge, Figure l. The holders generally have s<Jme means of showing •ockcl I, so that !Cs inay be in~rted the correct way cnund. When an !C ls to be ins.nod for the first tjmc, all i!S pins may need pressing mwards very slightly. Any pin.• obviously btnt in paclting should be carefully straightened with tweeters or sitnilar means. ·

123-4567

I~ 1~1~ 1:31:2: l~j 12345~78

FIG . I.

Most !Cs required hece have 14 Qf 16 pins, counted"' in 1'1gure I when viewing the JC from the t<Jp. ICs can be soldered directly in place, but the UJe or holders allows their easy r~p~ent, or :sub.stitution for tesl purposes.

The 74 TIL (uaruis1u1-lnlluish>r lc>gic) !Cs used require 4.7SV to 5.25V and nonmilly opcme frorn a 5V su11ply. Unused Ill''" inputs should be tttk~n to negative, 01 may be

2

connected to a u•ed input, or rna; be connected to positive through a resistor.

The NANO function is as follows;

lnpuN

0.0 0.1 LO I. I

Output

1 I I ·O

The binary coded decimal decade clll•nter counts from 0 to 9 givh1& binary outputs 0000 to 1001 at four pins. A decoder· driver decode.< these output• into the fonn required to di.•play numl>trs 0 to 9 011 an associated numeial. Oetails appear in the "'lated sec1io11!.

Ao inverter in .. m the lc>gic, low input gMns higll ootput, and hfch Input providing low output.

ALTERNATIVE NUMERALS

Coulltlng and simifai devices will requtre one or more ommerals, and the circuits shown here will allow 7·se~rnent LE~ and NiJ<ie tuhu to he employed.

Numeul& with illuminated =to" consisting of light emitting <ti<ldes, or LED numerals, may be operated from the 5V wpply used to power integrated circuits. Nixies, h~r, require a high voltage supply, though t ins can be of Very simple type, •Rd IS readily obtained by tn1mformtr operation from AC maJn•.

In ma•y <>f 1he circ11it< &lt<>wn, it is feasible to employ either LED or NIJtle numerals, with the appropriate LED or Nixie dJiver ICs. Titus as example,• circuit shown with LED<, might equally well he made with Nixie<, in mo•t c°'e"

Numitton and Minit"'n numerals, having small filamentary 3ecton, are also often seen, but ltavc not bc~11 dealt with here, End and side viewing Nixie numerals, Numitmns and Minotrons are from time 10 time •een Qll sale singly or in 1>3cl<s at low rost, and Ibis can be~ factor in •dOf'ling them for a display.

N1~1c circuits in this book are for the GN4 (and e<JUivalent) tubes The GN4 is end-viewing. with numeral• about l Smm hi!lh, Side viewing Nixies IIlllY be substltuteol, and woulol need

3

to stand vertically at the ed~e of tlte circuit bt>ard, or be flxed with the numeral side flat to the viewing aperh1re.

Other details appear in book number Bl'li 7 Counter Orivcr and Numeral Display Projects also published hy Bernard Rahani (publishing) Ltd.

GN4 "lixie Th.is has 13 pius, shov.•n in Figure 2. Counting from the space~ pin 2 is the connection to the current limitin& resistor Rl. This can be 33k or 4 ?k Ii watt for a 240V to 250V supply. Current drawn is around I l>mA to 3mA. Higlter values of series resistor, or Jowet HT supply voltage, will reduce brightness, but these fictoc:s ace not critical.

+ RI FIG. 2.

TI\e required numeral is illuminated by taking another pin to nc~ative. Pin 3 used in this way produc~s 0, pin 4 provides 9, pin 5 illuminates the numc1al 8, and so 011. !'ins J and 8 provide decimal type points in "'me tuhes, and should have a furdlcr series limiting resistor (about 220k). Surplus or ex­equipment numerals of thi< kind are readily tested hy clipping RI to pin 2. and stepping round the other pins with a lead returned to ne&ative, ol>seiving numerals produced. Very aged, mucl1-used tubes may produce part numerals, but mi#lt if to hand be suitabfc for positions where a limited display (such

4

al only 0 • l, or O· 1..:2 for cl0<:ks) wW be needed. No display at all prob.1bly means lost seal due to distorted pins. ·

These rubu may be in.sertcd in hlllders, or coonection• can l>c taken directly to !he piru, and in some w•y• !his has ad.antage~. All piM should be clean and bright. Use a thin fleiublc or sio~e·strand b1ight tillned.copper wire, wilh sleeving a fairly tight push· fit on the pins. Bare 3 short lengt)l of the wire, insert In the •leeving. and push on the r in. The leads can be as long as needed to reach from the board cariying the ICs.

Nixie• a(e operated from driver lCs whlch decode the binary inpul into a single circuit outpu l. Thu~ when the driver IC for the Ni.x.ie receives the binary equivalent of l, it automatically gi••• a negative connection t(l a pin wh.lch Is connected to pin J.3 of !he ~ude, lhus ilhnninalini l. When 1he binary changos to 2 , the IC ahers the circuit , •o thot this u complete4 to pm 12 of the :-lbde tube, to illuminate numeral 2, and so on.

The Nixie decoder-drivers are not used for .LED displays, as with lhti:.~e. two or more segment~ are jUu.minated simultaneously.

Conntctlons can be ananged to provld~ co11J1ts other than the 0-!I for which rhc tube i• made. to •ult the need for clocks or other equipment.

7 ·-Sector LEPr. Fig11n: 3 show~ a LED numeral with 7 1caments. Two 01 more are Wum1natcd~ to produce: numerats as. rnno,ir-s:

0 ABCDE.F I BC 2 ABGED 3 ABCDG 4 BCFG

S AFC.CD 6 AFEOCG 7 ABC 8 ALL SECTORS 9 GFABCD

Wi1h many cilcuils 6 omits A and ~I omits D. The \ndivitlu•I sectors are separate light ernil!ing diodes, and

all these LEDs are connected together at one end. Where the decoder-<lrlver is placed t(l control the neSl'tive circuits, as in <,rcuits here, commoo anode LEDt are required. This corrunon posih•e coonection is pin 3: 01 pin• J, 9 snd 14 with rome t»ros.

The number of segments illuminated. •nd dr•w\ng current, ..,;n derend on the numher r;)lown, ther• i• •minimum of 2

5

TOP I • · 14

'2 • • 13

·3 o ~c::::>~ • I 2

4 •• n=n • 11 s u-==u • 10 6 • • 9

7 • . • 8 FIG, 3 ,

scc1011 for number I, and maxunum of 7 sccton for numbcT 8 Current t:ik•n by the numeral thus •ancs considerably, and a 00111111011 limiting resistor is not ""'Y ""fafaetocy. For this reason, tach i;ector can be~t have \ts own resistor> between the driver IC and the sector pin.

Reierrin.~ to Fis111e 3 pins.and segment< ate:

A p in l F.pln7 B pin 13 I' pin 2 C pin 10 G flin 11 0 pin 8 Common, pin 3.

Tlms, to muminate BC for I, circuits are completed to pins 13 and JO. To obraio 0, circuits .. ould be completed to all sectors !isled CJtcept G, pin 11.

')'he decoder-driver !Cs used receive the binary input in the usual form, Cot l, 2, 3 and so on, and automatically provide output circuils for the cortect ~~ent~. Th~~ <lrfvers cann<ll of course be used with Nixies, for the reason ex1>lai11ed.

Ll:O numeral< are available In v~riuui !.i'cs and colours, and to plug Into 14 pin dual-in line ~otde1'. The DL707 has 0.3in high numben, fits 14 pin·DIL holden, and is suitable for circwts here

T e>Linl( from the forei:oing, it will· prove quit• .traightforward to ten a nun1erol which i• not giv\ng • oorrect display. Ir the numeral indicote< correctly when •prrorrtate circuits are made to it,

then the fault h .. lo he soujll1l ehewhere (<uch a• m driver coonecHoll3). Rut if the nullleral is found 10 be foulty, this :avoids any need for investigation of other wcuits.

OTJiER. COMPONENTS

Th< tran$lstors and integrated circuitl u<e<l here are easily ohtain•hlc from many sources, and are general!~· inexpensive. Beca11se of the latter point, the use of untested iurplus ICs is .not recomroeuded. 11tC$C ml:l}' have vnc or more detects:, truublcsume to locale.

Holdeis for the !Cs are not essential, but are reconunended for all p<>Sltions. Th¢)· are Dual In Uuc (DlL), mn<tly 14 pin on<l 16 pin, and are uailaolE in »anow •lyle11.

If an IC is to be easily inserted in a holder for the !list time, it is usuall1· necessary to bend its pins 1J!gi1lly to make thclll parallel. Thi< can be done with •mall pre••oue. Without care at li1't in,;ertinn, a pin may bend, or no1 on~nR• correctly with its i.ockel. Check each IC is the correct W•Y ruunJ, as ii is put in.

An IC can be removed from ito socket by inserting• thiu blade between socket and IC, aud levco lng It up• Hille al C•ch end. Cunlinue until it is free.

In •nme circuits, nperation will cease with a quite >mall drop in "oltaSJ:, so that a concct •upply mu•! be av•ilable. Other cin:u1t• are In• liable to fail in thu way. Some will operate partially, g1ving resuhs which could su~t obi:cure faults in counting or 01hcr circuiU..

EJtces• vnlt•ge, or wmng pCl!arity, must be avoided. Full details of \'arie>us means of supplying power are provided, and a small mains operated power supply unit will be of great utility.

RcsMors can generally be of ~ watt a~d ·smaller sizes, and these are ca<ie•t to accommodate. Capacitors, except for• few isol•ted positions, are low volta~e. Elcctn:>lytics may be 6 V, 6.4V, 9V, IOV, 12V or as convcnienlly ov•Jlable. These are ~netally for by-pass purposes, so that vlllucs •re not veiy ciitlcal . S'mtllarly, in the :smaller values of non-clectrolytic cal"cilor, 47nF and 0.05 µF (50nl') ore 1nterchan~hle. Rut m linung or oscillator circwts, values >hould be at gi.-en.

Rnards ere U. lin matrix,•• the IC< or holdc,. fit these. The various methods of wirinit shown generally require board•

7

without foil. If holders, etc., are placed one side of the board, and wiring is largely tlte other, rapid assembly is possible, with thu mrthod. Some units WoW WIICS run ahove and below tht board, to obtain cr~vers. This will tencrally require a larger board.

For se>ldering on O.Jin matrix l>oirds, a small iron, typically IS watt with bit to suit, will be almost e"ential. Tltis, with a good quality cored solder, will ruoke •oldeting easy. A good light ls helpful when working, and occasionally a hand magnifier to eXl!mine some connections mil)' prove useful.

Some l•youts show board• with undemcatb connection• vcrtic.al or horizontal. Board foils can he used for these circuits, foil• else ... bere being cut With a drill or :IJlO\ face cutter. Foil clad board may also be U5Cd with point-to-point ,.;rj~, tf w1med, by cullint foils each Side of connecting points. Fo~ .tad board can al"O l>e cleared by unroernng in etching •ulutiort a< if making a printed circuit; or by me•n• of a file, for small bnatdS, giving •upport by A flat !Ur(ace, or by U<e or 3 power abrasive disc, prefetably nu t-of·door1.

l..<lw voltage •witches cw be of tho small slide type; or can be miniature or standatd si:t.e tomites.

Where a single power supply unit 1s·going to be employed frnm time to time with yaziou• units, uclt may have a flex with non-reversible plu~, to match a !l(lckot on the PSU. Small, low-vultag.o p!U.!$ azul sockets arc »Ymloble for this pi.ttpog<.

Stnur leads are unnecessary, anu introduca troubles such as brpken pins, or short-circuits al joints. Mo;t connections can bo e>f ll>in wire, such as 30swg tinned copper. A stouter wire i• used for positive and ncgalive !inos, where <everal ICs •re pre•ent.

It is very useful to have a fow different colo11rs of nanow ~aua• sleeving, In put on leads, and helt> identify the.e. Very thin nex i• also best for some other purpos.:-, red for po>itive, bl.ck for negative, and other colours for •witching circuit., etc, However, a non·miniature flexible conductor should b< llSOd for the main power supply circuits, unless lhae are veiy lhort, anu only two or three lCs·ne pr<mnl.

POWER SUPPLIES

Cuncnt will mo!1 generally be den•ed from AC mains, a reliable and cconc>m1cal supply being obtained by lhJs means. Howe,-er. for some circumstance•. batt•T)· running is rcaliible.

Operation from dry batterie• will generally be for item; which require only• rcU.lively small current, or Q!e of a tyl"' oper~ted for short Intervals. llatt•ry running can o.lw be adopted in some other circumstances, as w}1en no main• will be avaibble, or when m11lns may not be used, or when an adequate current •upply is available, a. in a vehicle.

JI is lm~ble to state h.ow many hou"' d."' will be-0btained from &n} p•rticult r bauery pack, but some idea may be gained by iruertin~ a meter in one supply lead 10 nore aYeragc current dniwn. nus can be oornpaced with that taken by rhe typical l\and·lamp, prohahly fitted with a O.JA bulb.

BATTERY RUNSING

The 7400 series of !Cs normally operntc from about SV, with lower aml upperlimits of 4.75V and S.25V, and an absolute ma.,imull\ or S .SV. lt will be found th•I tnllny devices can Ire run frum • J..ecU or 4.SV battery. This has th• advan~age of lllt!<:din~ nc> .arie.i dropper 01 olher \'Oltagc cont.rol.

W'here t11e full SV will be nec.=ary. and cuuenr d<1lin is reason•bly steady, it is in order to use a 4-cell battery pack, for 6V. and drnp the execs. IV with a series resistor.

Where the load varies thmugliout operation, as it often does, the 11raii,ll1tforward series limiting resistor i• nol 'uitable. II is Uien best to employ a Zener diode for regul•tion, or transistor ot JC regulQl<m. With tht•e. !here c&n be an advantage in having a rather hl~er voltage available, such·u 7.SV, 9V or I 2V.

The situation for a steady current is >hown ar A, l'iguce 4. A 6V supply Is reduced to SV by RI, which drops IV. From Ohm'> Law, R = Vll (voltage divided by cunent). So if IOOmA will be required, I volt 1mut be dmpped at O.l ampere, 1/0.1, w RI is 10 olun. Olanges in current dtawn will cesult in corre.JX>ndin~ cltanges ill the voltoge lost in RI, •O tltar lite oupply di>C• not remain al SY.

9

r;:

CJ • • .. RI + + R I +

6V © 5V ® 112

-+ + RI ...

VRI t~ © + ® J .. 20

. FIG . . 4 .

The circuit al Bis slightly better,.,. con,tant cmrent drawn by R2 helps swamp cl1anges in ~urrent drawn by the cquipmen so the voltage dropped in R 1 Is subject to smaller ;·ariation. Tiie larger the current drawn by R2, the greater the impr<»c· ment. This is practical where• limplc mains unit ptoviding JA or more for R2 can be hrou)lhl into service, and a 10 ohm "'ir~ •'<>untl putenriom«er ma~· be eunnecteJ ai; in C, and adju:rlctl I for SV output at minimum load It is ~)$0 a temporary exped1e111 for accumulator runn!n~.

I) u.es a Zener dioM. Assunung a I 2V supply, Rl must dr~ 7V, to leave 5V available. With• SV ZTl rated al I watt, the ZD current c•nnot exceed 200rnA, thus RI ;, :;s olun rnw. In thi• case, an output of Q .. 200mA can be drawn. Should the minimum lo•d to be 1mwlded be known. thi• can be allowed for, to up-rate the ma.x.lrnum load. As example, ... umt the minimum load al 5V is 200mA (not zero} With 200mA flowing through the diode, the total through RI I• 4-00mA, so it mil)' be redtoced 10 18 ohm JW. )b~imum current which may be drawn will then be about 4-00mA.

Where RJ is too low in vlilue for the current the ZD rnt1s1 pas~ •l minimum exrernal lo•dlng of lho supply, tl•c diod.c

10

current i$ too great, and· it i?S clamagcd. Where C.Xl~rnat cu1rent exceeds that for wluch R 1 is suitable, the ll(llt~ge falls below thal of lhe diode, and regulation is lose .

.Un<r dit><lc regulation is coo.eiucol for some •chicle or aC('umulator nperated equipment. y.-here t.hc continuous drain of the diode is of no importance.

TRANSISTOR REGULATION

figure S $}\nw• a lransislor series rcgulalor f<it 12Y DC input. At A, the base of the NPN tran~i•tor fa kept at a •table voltage by the dluJc ZUI, whidt receives cumnt through RI, 270 n Y.. wan. A 400mW tliuJe is adequate here, as it only has lo conuul the b.ase current o f lhe uansinor. The emitter voltage, and con~uently output, i$ itabifocJ at ne111 tlte base voltage, fur tclauvelr lar~e chanRes in current drawn.

A smQI\ difference in pulenlial cxi>ts between base and emitter, and may be around 0.6V. ·zn1 can thus be 5.6V, for a 5V output. An output test with a me ter should be made before connecting equipment.

+ .. RI

T Il l

@ .. ZDI

•

+ RI ..

@ TRI VRI

ORJ + ZPI •

R.< - FIG . 5 .

J,l

Cin:uit B allows adjustmenc of output voltage. ZDI providl • :JighUy higher voltage th•n required, md VRl allows tile bu of the control trarui.rtor (•nd oulpul voltage) to be set, with the 111d of"" accurate, high-rc.11lance •oltmeter. ZD I may llo 6V or of higher voltage. YR.I c<n be arountl 500 ohms, or may be of lower value, with R2 in ,.,,;.,,, to open out adjust· menl. R l i< ieduced to 150 oh:m, 14 watt. R3 may be pmvidei to draw a small current ~hen no oxtemal lwd i< piesent. R3 can be 470 ohm. .

Cl can be added for an AC operated supply, for eleclronic "11\(>0thing of output vi• th• transistor, and can II• 100 µF, 10'

Various NPN audio and ouTput type tran<istors may be used 10 •uic the maximum current likely to he required. The 110 t 39 is suitable for J .5A maximum, •nd for brger current tile 21\3055 ;,; unlikely to be e~cccdcd. A ~. panel, case or hcot·sink should be utilised ••mounting, to keep tcmperatw d~wn, exc~pt for Jow currents ,,.,rhere this is unuc~eJ~ry.

AC SUPPLY

F~111e 6 shows meam of obtaining power from AC mains. C1<cuit A has a centre·t•pped tron.rormer. With this met.hod. Cl will charge up to ju~t over I .4 t!n~s the indicated rectifier cunnec1ing roints. So with a 9-0- .9y >econdary, Cl will ruch about 12.6V. The voltoge across Cl will'fall, as current "dr•wn. When th» has dropped 10 the le¥el where 7.D I

+

® +

- + +

l _L. F I G . 6.

12

e (Figure S) can no lunger be supplied , control ceasu anti output

voltage also falls. Cl can usually beeboot I SV worlting, and atleas\ 1,000 µf

for each l ampere. If the ocwndary "of ltigher ,·oltage, Cl can be uted lo 'uit.

Circuit Bis similar hut uliC• an untapped secondary. A •insle 9V r.>Utpul replaces the 9-·0-9V of circuit A. In each case the rectiftero may be SOPIV IA, or IN4001 and similar type•. again up·rated where larger current is wanted. A bridge may be preterrctl for .ll, insread of iJl.dMdual rectiJ\ers.

·n1e circuits in Figure 6 are not intendt d to supply current direclly. but to provide an input for resula ton such as those in Figure S from which the required SY will he obtained.

Figure 7 ir • complete :.upply. Here, a 6.3V heater rype secondary Is conveniently uiiCLl to provide some 7V to llV or w aervss Cl (1000 µF - 2500 µF), ae<:ordlni to load. The diode ZU I maintains Tri base at appmxlmalely 5.6V, for approxi­mately SY output. C2 (47 µF) is for electronic m1oolhing, and is sometimes omitted. C3 (220 µf) provides a·low impedance reservoir as abrupt change. in current draln arise with LEOs, .decoders and other ICs.

rn building thi• an<l similar circuits, draw current from. 3-pin plug with a 2A or other low ,.ting fuse. This allows c..rlhing uf the secondary, for safety. A neon in<licator {small

F IG . 7.

13

nenn with 270k to 470k seeks resiitor) may be placed across the transformer primary.

An earthed metal case ls preferr<J . and Tri can be attach 10 a smsll heat sink. o< may be mnunted o n the case. F..xccpt where lhe <ink itself is foxed with Insulated bushes and washers Trl i• isolated electrically ftom the •ink (or C!!Sc) by me am of T066 insul.tion set for the 2N3054, or T03 set for the 2N3055. 'This has• thin shapcJ in<ul~tor to go between t1ansis1or and sink, and bu•hes tn 81low tLXing while mainlainl . b1sulation between transistor body and case or sink.

A tagboard or tagstrips wiU .. rve to mount the capacitors and other items. p.,,itive and negalive output so~kct• will &!low easy con,,.,ction of e><temal eq11ipmen1.

A check of output an he made under anticipateJ load conditions before lir$1 usuq? the wpply.

IC REGULATOR

The LM309 imcgrated circuit 1egul•tor< are panicula•ly useful for 7400 type ICs and ulher 5V supplies. These regulators automatically provide SV. They have internal curr~nt \imhing, and thermal <hut down, thus protecting theni­selves and the power supply fo.im a •hmt drcuit or severe overload. The 1.M.l09H hao • TOS case, to which a finned heat <ink can be fitted, and iuu11able fur 200mA. The l.M~09K is of T03 siu, and •Uilaf>le fot IA.

Uese regulators llavc only three connection•. in, out and negative. Ibey moy be mountod on·hoard in some applic•tion Here, distribution of power is at a higher voltage, and each bubrd with its !Cs has its own regulator. This ha.' advantagts for farge equipment,., it avoids extensive distribution of• re~ulatcd supply.

Figure 8 is the circuit of• complete SV supply. able. to provide·in exces.i of lA , using the L~l309K regulator. SR may be fnurindividual IN4001 rc~1Hku foTup to !A, or any ' l nular I A 50PiV IYJ'CS, or l .SA •ecllfiers for maximum rating. Altetna~ly. a bridge type may be u3ed.

There is >0me la!ltude 111 T l .c<:<>nd;uy, but approximately 8V 1hould be found across Cl. at least, under full load, Some 6.3V lransfom1ers are suitable; others will not allow this tn be

14

~

,,. +

SR + +

... r-c~ ~

{. ri T_CI

1 -• F I G. 9 .

maintained. A 6.3V winding of fairly l.rge currtnl roting, such as 2A <>r mnre, i• m~t likcly to he •ucc .. sful. Otherwi•e Tl scoondary can hest he of slightly Mghef voltage raf.ing, such as 9V. A centr~tapped secondary, A in F~~u1e 6, can be used instead (cyplc•llY ~)-0-9V or similar). Tf th• voltage·acms~ Cl falb below about 7V, regulation rnay be los1.

The LMJO'JK i~ mounled on the Ch3ssls, pa11el or case, or on internal metal lmcl:et, and thb i• common to the negative line. Heat to~ c;irried away is not~ i:reat. As example. with 9V input, and 5V outpul, at I ampere, only 4 waits dissipation arbe11 in the JC.

A meter check prtor to first use should show that the out· out is •ery cl.,.e to 5V. Thi• i• not relaled to the input voltage of the IC, except where T 1 provides insufflcient voltage. CI m•y be 2200 µI' -4700 µF, 12V •nd C2 JOO µf, JOV.

NIXIE Svl'PL Y ii round 2SOV OC is required for the f';bde, but only about I mA h> 3mA will be needed per numeral f igure 9 is • sullablt S<Jpply. The vnlt~ acr0$S Cl will ~ approximately l .4 tinieA the l<.MS seeondary voltage of transrormtr Tl. CJ can be .l50V, R µF to :12 µF, and R.l is a bloeder, and cs.n l>e 220k 1 \\·alt. The rectifier can l>e a 2SOV 40mA brld~e. or four

15

•

I +

~--.. ·--- -----C-1 r_. RI -

I \. N E F IC . 9.

llld hidual rectifiers if picfer.,,d. Halt-waw: rectification is also f<a<ih!e.

Operation from 2SOV will l>e thrnugh an individual 33k resistor for each GN4 tube, or 47k for JG\ 13 and 56k for J(N3 tub.cs, with 220k to 47Uk for a d teimal point. low voltage reduces brilliance or result$ in no dl$pl~y or imperfect numeral: High vol1age causes• reductii>n In tuhe lite.

With a particular lransfmmor at Tl , voltage may be reduced by pl..:ing a resi:!tor bctwee11 second.ry md rectifiers or between rec liller positive and Cl pc»ltive, and reducing the value of R I so that some ado/l\ional stea<ly load is present.

1>raw mains power from o 3·pln plug baving a 2A fwe, •nd eorth the se.:ondorr ciccllit at ncgat ive. at $hown.

I !tc Nixie •ui>rly and SV sup ply for the !Cs c:m he ohtalned from nne transformer, using also n low voltage •econdary, and IC i>r 1ransis1or regulator, as Shown.

Multiplier for Nixie Su11ply A hi~h "'lltage supply for a Nixie numeral tube can be ol>tairu:d wllhouc chc use uf a tra•sforiner having• high tension ..:con<lary, by using a voltage quadrupler, Figure JO.

fl. transformer ... ;Ill J2V and '24V :ld:On<l3!k~would all-Ow the 12V tapping lo be used wilh ns own rectifier, Zener diode and series transistor, for a 5V >upply . The 12V and 24V windings in ""ries will proviuc 31\V Input for the quadrupler. If placin11- the windings in Serie• prnvldes a reduced voltage,

i6

Jr- I N4004

--c:Jl-:j;-

+ + + -+ +

] 1-2-·J IF-

FIG. 10 .

reverse cunncction~ tu one. 01her trunsformen may of coune bo used. TI10 c•entual

outpul ,oltase with no load is •pproxlm3tely 4 x 1.4 x RMS <. seconrl~ry w ltage: Lo•ded, this falls rather rapidly, and WM

found to he J 80V with the cir wit. •hown. I' our l N4004 Qr similar rectifiers aie ~uitahle. All the

c•p>cilnrs may be 4 µF, J 50V. Cap•clle>rs C>f higher working volt.all" m•y be used, and all need nnl be of the same voltage ratinR. They should best be of about simil>r capacitance. and can be o! lar&er .. ..i~, such a• ll µF

Thh drcuil hos no advantage over dint shown earlier, except th•t a high voltage .. condary is not required on the transformer. Rectifier~ anti capacilors arc readily as<emblcd ou a toghoard .

17

FR.OJECTS

NIXIE NU}IERATOR

Various.popular ~anw' which combiM skill and chance use a to obtain number>. ·The simplest (e.g., such as Snake• & Lad• arc wholly chance, bt1l the more skilled (such as Dackgammo1 are determined in varyutg d"f."'es by the playc11' abilities, tht element of chance alkiwin~ the ks' $kilful player some s=u The Nixie Numerator $hown here will replace a dice . As !lescnbed, it provides a number from O·to 9, rhus slightly 'opening out' sume gamu. This is a wcl<:onied.modiflcution for some playeT!. However, wl)ere lh• usual 1 to 6 is requirea this can be obtained by the modiftcotion• de tailed lattr.

Pigure 11 is the complete circuit (except lor tloe 11ower supJ)liet). Two tra,,•istcir< 011erate as a niultivib,1atm when l push .witch is clrued, Y11lues l>eing chosen to gi>-e a vi<il>le y•I, quite rnpitl ch.nge of <lispfay. Cl provides electr9nic ' cmnmenuuu•. pulsescontinlie 10 arise for a sft0tt time after the switch is released. '!'his simulate• the effect of manv mechanical de\'iCC< of similar kind. '

Pulses go to l 4 of !Cl, the binary codeJ <ledmal decade counter integrated circuit. Thi• IC proVide• outputs along its J, 12, 9, 8 and 11 ta&' which arc 0 to 9 in binary fon)l. ltl Is a <lecouer.dciver. and decodes its blnaT)' Inputs al 3, 6, 7 a 4 into !tingle ended output< at pins 16, 15, etc., which conne<1 to NiXie i•u1s I 3, I 2, et~ .. to di•play numerals 1, 2 and •o on.

I t i• appar~t that al>.it ran<lom numeral display is wante<l, the 01~tp1.1u 16, 15 and ~o on, to 2, coul<l.lie connected to an) of the Nixie pins 13, 1·2 along to 3. Thece would then ~ S01'Q chanco, but permanently set ••qucnce of numeral•. This is 1 readil y provfdeJ by taking these ten lead• ar random t0 the pl They are shown in correct order in Figure I I because thi•· does not effect !he eveulua] working of lhe Numerator, an<l COlll<l catu;e oonruslon loter, " hen referring to cifC\Jits in whil.\l mimt>ernnust ap~ieilr correctly.

Thus the nnmbcrs0-9 foUow ·~h C>lhrr and re peat rapitllv ~"long a$ !be push switch is held clo.-d by th< player, but •to'!: a little wl<ile after this i< released. The mullber nhtained remains di•played·1inlil th< swlrch is pressed again.

• •

•• ••

T•ts 5 r:ii the IC~ar.d;ir posiliVnuppJy lines, and rn . .,,i:I 12 ~re cun1mo11 ~1\ltive, as Sho,.n. l'ur1.her details on huilding •Pl"'•' lalcr.

---·----- ----·· .. -·---·----.. + ii\

! .,.

b •

-'------__;

l ..___..._.~-IY

._,

---.-... - i ~ -l

=! 1 ::1 I a, l

i}i ~

·---... ·------_J

p (vmpiment$ (or·,¥f:de 0-9 Numerator (FigursUJ

(R•~istors ·~w 5'1<.) · R I 2:2k !:.I 47nF R'.? 33k Tr 1rrr2 2N3706 R3 I Si: IC! 7490,'\ R4 lk JC2 7441N R.S. 33k ~W Push swltclt er 470 i.<F 6V '.\ixie GN4 C2 2 µF uV 16 pin arid 14 pin DH. hol~er~ C3 2 µf 6V Roard

I - 6 N umerntor The drcuit ofthisisshuwn in f igure 12. Adif~erent

integuted eircujt u U$ed in Ille IC I position, and oocputs are so arnmged that the decod.e<-dmer I(,".! is openitC<I ooly in stKh a woy lS to obtain I tu 6. t here ls not • delay ""ch as would resulr if die o ther ouip\lls were merely disconnec~!l.

Jn Figure 12 pins 6, 5, 4 and 3, for the unu""d numet'als 7, . &, 9 and 0, are connected alread)' if the Nu1rielator is derived

fn:>m that for (}--9; dcS<:ribcd •arl\or. If the tube is connected for 1- 6 only , and ha7,e nppears, ~onMct these ieads al~o .

.(;cmp()rtents for J . 6 Numerator ( Fixure 12} (Rui•t<m Y.<W 5%)

RI R2 1U K4 R~ ·c1 C2 (',3

2.'.ll 33k I SI< lk 33k~W 2µ f.6V 2µF6V 47nF

l'tJn~tr11c tiou

Tr!;Tr:! 2N3706 !Cl 7492:\ 1C2 7441N l'u•h •witch Nix.lo C.N4 16 pin and 14 pin J)JL ltol<l•r1 R<>nrd

figure< 11 and 12 are"' similar that on~ general layoui will be "'•U suited f.,.. either. Thus only u~ is actually shown. The mall! diffcttncc arisu ill the c01u1eclion• to ICJ .• namely 9--0. 8-' ••d JI 4 ror t he(}--§ Numeratnr, widt 2 and 3 alsu 1;roundcd, while only 6 and 7 arc $r<>unded for ti.e 1-6 · Jllumcralnr,.and JC! to l C2 l•ad• •re 11-6 and "-7 with 4 nf

'20

IC2 g1<.1W1<1£d: By tuing J -&lied f>oatd !.ht,.. ci...n~ 3n:t readily accommo.)arcd, or even the on• lype changed to lh<> orher.

f.igure 13 mow• wlrln~ on<! layout for the O· 9 :\ umerat<J.r,

"' '

" "'

21

__ _..,.. . '. -Nl :: I

' .. !!'\ UV "'

,_,__

I i

,------- --· .. ·- · ·---- ... -, O "'I "'" "" ...... .. ..... : .. .,. . ...

' ' : ~11 _______ __ ~ -- - ---~-r ~ ---(.'. \.. 0 .,

:"'. "~!".R.lJ" ····-· ····-······v/ ·-.~ I 1

I N : " :

l ~ r'~ r. . + u • r-, : ... , , . . ' . ' • ' • I ·-· ' "" . . ·-·--·--··· .. ····· . . ... . «i : a:: I ;------- ....... ,..1 "f! : a:; )

Q, • l. .~... "' + CC1 • , , :- ' () ·1" .,.

r .. ~ "----..... ................. ;....___,. ... __ _____ ... __ ___ ____ ,,,

: ~·2· .. · ·::· ~ : f:!·:·~~ : ~~ ~~ ·~ :J; I

j ~ ~ ~ : ... :--..:.; -:::~;·, ... ~"- ~ !;:_: j I . ' I .........:-= O•··· -....:._;c_......;

; ~Q ,.. .

~-~ ....... ~~ ' ' ._.,;... ___ ~·r---+ ...... : --·· .,_ _ ___ ~,.. :::~:!~::::J 0

......... --- .. -.... ,. '"' . -.... -.......

using a boud 17 x 21 holes in liize. Stout wire;, not re'luired, and is best avoided, 28swg being a~•quate. The undenidc of the board is shuwn. The !Cs. cCJmpononts, and some connection,. ln broken lines, arc on the other side of the board.

To take the IC hulder pins. O. lin matrix perforations tre neccSAary. A Sm•ll hon should be ulCd for <O!dcrbig, as there ;, not a.great deal of free space where m•eral connections or joints occupy adjacent holes. Resistor, transistur and capacitor leads come down through hoks a• shown, 11ml connec tlon.s· can then be made to the variou• points.

Suldei on red 3nd black fuxihle leads !or pomive •n<l

22

n•@•livc 'UPl'lies. Also two flexible leads at 1', for the push switch.

Tenexiernal leads run from IC2.. from I, 2 anti 8 to 16 (exdud1ng negative at 12}. These may be very thin flex; or thin >inglc itnntl wire with small diameter h1sulatcJ sleeving rruiy ho u~ed. Take each of these !cods in tum up through an adjacent hole, as shown. leaving them a few inches lont.

l"ig111c I 4 show< a convenient method of mounting the · C.N4. The panel h:lll an aperture sliglllly too small to allow the front (lf tho tube to pass through. A 6ba bolt is fitted each side of this. hole. A piece of illsulating material, such as paxolin oc hardboanl, is cut and drilled to fit on 1J1ese bolts, and this h•s a =•lier hole, to clear the tube pios. The tube i< placed between the partd and this piece. ood set with numerals •Crlical, and nuts put on t<> clamp it in poslrion. No force should t>o u .. d. The flying leads can then '.>e taken to tile various pins, using short lengths of •leevin~ io form push-fit councctiuns, in the way described.

nus method of assembly cau readily bo extended for more tll<ln ope tube, by drilling the panel and a long backiug Wit? for the required number of digil<. One h(llt each end, and one between digits. will be adequate.

Where chassis type holders witJ1 fixing holes are used. these may be mounted on a suh·panel in the usual way, an<I will hold the lube< in pl<)ce Surplus circuit-board holders con.silting of a ring..of $0Ckcts may be mounted on a thin insulated panel, or may be put un lhe tubes after th.ey hav~ been fineg a~ in Figure 14. It is necessaiy to use thin matorfal for the hack Slrip.

II is also quite cai<y lo mark an insulated panel with the pin position•, using ink on the pins, or carl>on paper, and lo drill smoll holes for them. Tubes can then be mounted by fitting them to tlte panel or board, anti can be held in pface by the leads themselves, filled closely to the board.

Run • ileparate imrulated lead away from pin 2, so that it can y> to tile serie• limitiogre$l$tor, wluch can be rnounted oo cite board or on a tag .trip.

\Virtng :is in Figure 14 will allow tJ1c ranel with .tube to be set n.1 over the circuit board and a depth of about 3in {7bmm) inside the c""' will be <ufficient. The pu&h switch is on the

23

f

"·· ·. •.•. ::.:··

. · , . ... "::::~::

•

. > ... :• 0

O .. <:.

• ... :~··· ••

"

p~nel (or case top) near the tube, !hi• giving casie8t operation in play.

''STEAUY HANU" WITH COUNTER

The amusin~ game whicll oomists nf thre•ding a •mall nng a!OUR a stout wire or rod, while avoiding cont•ct, can be

24

1mpruvcd by •tltling a counter. Thi• is tnitiall~· (et at 0, but etxttact ~tween the ting and rod advances this, and the test is to complete the wltole 'course' in a given time with under 9 indic•ted.

Figure 15 is1he circuil, and lhiS inch.u.le~ a muHivibrJ.tor which prod11ces an audio tone when rina and wire touch, as w~ming. Suitable valuL'S for RI Lu R4, and C l and C2, are given, but there is actually considerable Jati111de here, and in the transisttn·s u~d. Smaller capacilor values ant.I lower value resistors ralse pitch. C3 couples the audio 10 a small speaket, connected at S. This ~hould be of 8 ohm or higher impedance.

The multivibrator part of the circuit is readily checked by itself, by complcling tltc connection from VR I to ncg><tivc.

C4 cha~cs each time ring Hild "''re iouch, mm-ing 14 of IC2 ncg;iith·e, through ltS. This ad>anCC• the count, tlecoded by IC I, •nd laken lo the Nixie lube.

Without thi• delay network, formed by the ca1•acitors and includist~ VRl , whar is arr>arently a sintllc cuntacL bcLween the ri.nl( »OU ~~tire may in tac.t be reve.111.eU a' a v:hole s;ucce~sion of contact. and interruptions, of extremely short duration, but able to advance the counter. In use, set VR 1 so that • brief hut definite con lacl between the ring and wire c•u•es the speaker lo sound, and lhe count to advance by I. C4 tends to lcnglhcn operation of lhc audi<> oscillator, and sound rrom lite 'llCaker.

ll 1t fess.bl• to use a longer and rather 1no>rc diJT1Cuh 'cours->' "'dlh 1his 'dJtaugetnenl~ compared lo that \l:here a single cQntact between ring and wire will lose the game. Book number BP48 Electronic Projects for Ue!(inners, published by Beniaru lhli•ni (publishing) Ltd., contuin< further co11structional dct•ih .

The Reset switch between 2 •nd 3 of IC2, and 11cgalive line, is normally cloml. Monlenlarily openi ng this returns the tulle intlicuti<Jn lo 0, for the next attemr>t. The Reset switch C-Jn be a pu<l1-button breaking circuit when pressed, or a spnnR-loaded t011glc wired to gi•c Ii..: ,;imc result.

A>sumlng that this game, like others, can l,., run fiom a gencnll pu.rp<)SC AC opcraleo power •upply, no furth~r ""'it.clling i." rcqujred. The transformer primary or nlain on.off ~"'·itch will control both lone and IC •uppllo•.

25

Qim1>onenu for "StteDdy Hand" with Countu ( FiguFe 1 SJ (Rc•i<tor. 14W 5%)

R I 4.7k Jtl lOOk R.3 22k R4 3.3k RS IOOohm K6 lk K7 33k ~IV VR I 250 olun prC·i<OI CJ,C2 0.1 µF 1.:3 o. 22 j.tf

"TWINKLE TREE ..

C4,CS IOµF6V C6 47nF Trl/Tc2 2N3704 IC! 7441~

TC2 7490N Reset '"itch Nixie C::\4 14 ant.I l(q>in DIL holders Board, etc.

This ls an easy proje~I for beginners, ant.1 lw a number of oppticalious. A •equence often light emitting diodes flash o~ one al• tim•. this beln~ repeated so Jong as 1!1c circuit is ope I'll ting.

The LEDs can be used on a small table dccorJtion, in llte form of a Chri•tmo.• tree. e\'ergree.. or ortificial, or a •uilablc 11lcture; or they may be placed at vadous points on a hangJng dcenration, such as a ln111ch of mistletoe, nr can be incoiporat.ed in other <lccomtions or models. Thh provides an intere•tlng and novel twinkling effect.

The same circuit can be used wilh the LEDs placed cound a numbered boor;!. so lha1 rhey 11""1 on In tum "'ith a re»OIY\n~ effect, anti can be halted by opening a sw11c1L ' Figufe 16 is the complete circuit, including a smaU maim

power supply for opera lion from AC mains. If runnin~ i• lo be from an existing supply, or bat1e1ie•, omit ZDI, DI, RG. C4 and Tl. The supply negiuive g<>es to the "E" line, and positive to lag,• 5. It shou!U be oppmximately SV, a.• explained.

The multivibrinor Tr I fh2 prod\ICCS pukes "ilich fonn the mp11t to the bina.ry coded decimal dee.de counte1 JC'J, at tag 14. This IC count.• lh• pulses and provide• a binary output at 1- 12, 9, 8 and JI. Tag 5 is its po•itive line, and 10 negative line.

Wirli counter. havin@ two or more numerals, as shown later. l~e IC Can pass on a p1dse to the "!em" &ecti01L Here. it Is

27

I I I

:::

.... 1---_J

"'

Q

"' ,- 7 .l -·---1 1·

~----- l ____ _J

0

... --~~.....;;;.....~ 28 ·-· _,:___ ___ _ _ ,_._

.,;

u.•ed al<>ne.ll.lld :.-e~eal~.the same sencs of output< o~~·af\d ovu <0 !Qng ai pulses ore applied lu 14.

ICl "a decnder·driver; l ts purpnse is to receive the various inpuis at 3,6, 1and4, and decode them into ou1pots al 16, 15, !i, 9 and su un, olung tu 1.anu '.?. Thus e~ch.nf these ten points (J(> to 2) provides a circuit 10 the 3pprOpJia1e LED in turn.

All ttie I .ETls are returned. throust1 the co1111non limirin~ resistor R$, <O operate from the !>ame SV line. Th• effect is, that each UlO i< illuminated in turn, alonR che line, and wl1e11 the last is reached, this is foJlow,'<l by th• first, and the <£quence i• repeated. Check the l,EO r<>larlty, atld mark this with red sluv1119, or other means, if the. U:D. hOYc no means of idenuilcauon (Imig kad Of Oal si~c).

Pur the 'Twinkle Tru' tlie ten LFDs ar" scattered at randoo1. and Jny J,1:0 could be connected lo •ny of the outputs 16 lo :2. Howe\-er, for the Roulelle, ·where an apparent rotating indicali<>n i• wanted, they should be U\ •eq11•nce in (he·order sht>wn .

Onl~' one LED is on al a thne, so current drain i!i only some ~mA or so, ·and this makes batteiy running feasible. This can be 5V, obtained as expl3ined (6Y must not be used), or can be 4.5V from three I .S V cells.

Tl (6.3V secondary) provides about 'JV across C4, and R6 drops lhas for the 5.1 V Zener diode ZOI. I\ met.r placed "~<>$3 lhb diode "'1ould show about lluS voltage. ,.. Ma111s current ;,, drawn. from a 3·pin plu~ with 211 fuS<O, and tit.is pruvidos safety earthing of thO" secc:mdary and Ji;w volt.age circuit. A 'double insulated' transfomier spedfied •S requiring no ca1chio~ may be opcraLed without earthing. :\attually conslruc.tion an<l \Vi ring must. ai;:sure that O(l mains voltages can r.ach cf\e <ec<>nda ry or low voltage circuits.

With 3 b3ttery or ext~mal power l'""k. •~'"'e polarity;,, correct. A thin rc<l·black cord frnm the unit, with 2·pin non· 1C\·eraible pl'ug and matcliing socket on the power rnpply. will be con\•enlent for ~ SY fot tlli$ and oilier appaiatus.

koulcllc 'lbc only change required i• to place a 1•ush·button switch in the c:c>nnection hctween the transi~tor e1nirters and negatj~·e

lure.· The l.F.Os will then be illuminated in sequence .n long a thl• i• lteld ·closed, and Or\e will r.:main lit \\1lell 1l" releaoed. A sliAAtly hif)1er •reed may be ad<>pted, by changing R3 to 15k.

i\ hoard should ha" "citcle drawn on it, and shuuld be divided inlo 10 p;iinted sectors, each with irs ow11 light emitting diodo. The LED. can be a pu!f1·li1 in holes drilled \n rhe board, <U Or in irommet.s, wilh connections unclerne:ath. Join all 1•i:>silivC> together, a11d to RS. Ten thin flexible leads, rnni:ting from 16 to. 2, call then he so!Jcrcd w the individual LEU..

Tile push swllch is best 0111<1p of the box. With battery running, place an On·off switch in. one: battery coon~clion.- Tht mains 'Twinkle "l'ree' or R.ouklle ;., intended to he unplu~ed fton1 the mains 14•hen not in use so does not require .11. S\Vitch.

Cirmi1 Board Fi~ure 17 shows cumpQnents on Lup of the board, which is 0.1 in matrL~. 14 x 18 holes, with fnlls ruu11ing vertically. \\1iere foiis are used as cnnductors, 1hese are indicated with brokeo lioes ll 1s necessary Lu ma~c foil breaks between tho~ p•m of·the cin:1Jit which must Ml !>e connected, under Cl al)d C2, between upper and lower rows (lf tags of each TC, betwee11 J, 2 an<l 5 of IC2 an<l 14, 13 and I 0 oflCJ, a. clear f11>m Figure 17.

First place the IC holders in p<>sitlo11,Jd solder the t~. t:se a small iron and amid exee;s sold~r. }i<1rt7.ontal wire• in Figure 17 non on tup of the board, andcan be 24swg wire. l't~ sleeving on the ludfroni !Cl 5 t11 R2,.and i!lso solder on red and bla<k flexible wires for the supply.

Note that the base and collector lead• of the transi•tor.s are differently posiliuned.

Foil breaks can be made with a f•w turns of a sharp <frill, /1eld in the fingCJS or in a handle. l!x;amine die.c carefully to :.ee that each conductor is cvmpletely cut, and that pnints or foil arc not >preod outv.·ards to tnuch ad.ioining foils (lf joims.

If wished, tl\e transislor multivlbrttlor can he tested witll heauphones or similar mean; in advance; and sho1\ld be hcanr l1:i protluce a contin\Jous seritS of pulses .:at n1oderat.e spcctl.

The inte~ra1cd circuits will usuall)· ha.,.,,·pins $J><C•ti tuu

30

ci ..,, ___ .... _ ..... ._ __ . ....._ ____________ _

..---'f7-- -l-' 1 I 'i- Q

"'· - -·+--; _ _i __ ·"' ' ., -i- ~I 11

• !:!I +..,j.._,,, \.__JQ1 +"' -·i..._ ,

.;. !:! .. !-.- --- -- = "l l l ~,; " :b --- ; • =~: :t I

u

--~--- ----J - '!!JI .. • I

----0--------------' "' __ __i

wide to flt the S()Ckers easily. 11tcsc c•n bo bent in very sli~ttly by prcs~ng lhe IC on a fl<tt surfac~. As.1ure the indentaliun or sput marking l is at the correct end of tho SQclcet, in eaclt case.

The teu points marked L take tl\u1 floxlble leads, wldered through tho holes, and later co!llli:clcd 10 l\~ti'I¢ at tile individual U.Ds, .a in Figure 16. I he complctctl board can be filled m a smiill plastic case, wh.ich may alw hold the ball cry, ~·'here thit; 1i; ti'.') be ur.ed.

For the Roulette game. dis.;ormect the lead which runs

31

I

---------"~---~

from cmitten to 2 of ICI , and hring l'!'O leads from the.e pomts t.o a <wilch wMch makes co ntact when p re,.ed. The periodicity is •lightly increased (chis may be done by reducing R2 or RJ. or carac11or Cl or C2) so that motion is too r• pid for any(lne lo select particular numbers.

It wUI be noted that in Figures 16 and 17 the numbering for !Cl and IC2 is when v1ewin~ these Cron1 above.

Components for "Twitrklt 1'rec 'und LHJ) Ro.,leitc (Figure 16) (Ruisiots II\\' 5~)

RI 2.2k IC I 74\IOX R2 33k JC2 744 IN RJ 33k D I 1N4001 R4 lk l.Dl $.IV 400mW Zener RS 220 ohm Diode R6 33 ohm *W Tl Trsnsformer wilh 1;,3v CI 2 µ.F 6V secondary

·c2 2 µF 6V Push •Wilch CJ 47nF or 0.05 µF !)IL 14 pin holdtr C4 1000 µF l 2V OIL 16 pin holdl'r Tri 2.'13706 lOoffLF.Ds Tr2 21'3 7()6 BClard, e tc.

SIX-SPOT

The Six-Spot uses a comhonation of gates, opera\ctl from a d ivider which is pulsed by a multivibrator, and produce< a d1'play wllicli r~emb!es \bl<t of the u•ual six·sided dice, It can thus be cmplDyed for various games. The d ispl•y changes continUQUS!y while a p11sh.switch is held closed, and remains illuminttted when tt\e switch is released, so that the number ~•n be read. The changin~ ur running speed can ht read~y modified, but is a littl• too fast for auyon~ to select particular wan ted numbers by releasing the ~witch.

The Six·Spot consi.•ts or three secuons:. t~• 2·transistor multivibrator, which produces pulses to drive the !Cs; I~ four !Cs with gates •rr~nged to produce the ~quired displ•y, and the light emitting dioJes, wi th tllelr series limiting resistors.

Current required Is about 60mA to 80.nA or so, •o ·Utal if

32

"'"lied operation can lie ftom a battery >upply. An on-0ff switch is pbced in Qne supply or battery lead, to switch off c<>mrleteli• whe!l !he Six-Spot is not in use.

[..ED Sectio!l Th• top of the caso carties the LEDs providing the display.

and also the (M!Sh-switcl1. 'Ibis is of con•en1iun:.J type, closin~ ,.i.en pressed. Tit.is cumpletes the nega!h'C circuit to ooth the multivibrator cniitters, and the rate at which the display run• n1ay be modified by altering the valu03 of Cl and C'.! here, (II' tho values ofR2 or R3, Figure 19. Smallur ca1>acitor values raise the changing freq\len£y.

Tn ecnnom~ oo sp.cc, the LEDs, \\.1th scri., resislors, are fitted to a neat top paMI, and the muhivihrntor and !Cs UCCUP.Y a boartl to be mounted underneath.

1:isure 1 !.\shows the underside of the LEO disrloy. Tlte LEDs ~re arranged to llg)lt in arrangcment1 corresponding lo 1he spots on a dice, as lnd!cated. Only 0 comes on alone, indic•ting I. More tlwt one circuit may be completed . Thus A. II, F and G indie•le 4, wh~ <\ith D .J.w nn, 5 is displayed.

RI limits. current tluough A and G in series. Simit.1ly. R3 is fu• C >nd R, and R4 for B and F. Ho1>ever, R2 is for D orily, so is of higher value.

Check the LEDs for l'Olarity, with tho s11p1•ly and a limiting teslstor, •n<l if-no po!Jtrlty indication is present, provide thl~. A touch of red paint could be use<I, or $hOl1 piece> of red sleeving. Do nut bend the LED legs near the bod)', or the LED may fall to worl< afterwards.

/\convenient .size for th• board is about 3 x 3in (76 x 76mm). Th• LF.Ds may be a push flt in hole• drlllod for the purpose, and be ~cured with adhesive, or can l>e a pwh fit in ~mmmet~ which in turn can be put in tho holes.

Thin. flexible leads will run from the points shown, to 3, 4, 8 and 11 on the lC bwrd. Also pro•ide a n:d flexible lead for the comrnon po1dtive.

Components for I.ED B(){lrd (Figure. f8 J RI, R.3, ll4, 120 ohnd~W 5% lU 270 ohm !GW 5% 7 off 7mm 01 similar LEO..

l'llnel •1>1•rox. 3 x 3in, -(76x 76mm)

33

:"· + +

oil ... Cl ·.·. +

"' ...

't "·· •. C!

... :·: .. f

··. + .- ., "'

" ....

< f! u u. + ii( +

+

[JDDO o·~Fl o oooLJbJ

The llD board anrl LEDs cbn l>c te.ted by takiiig the positive wir• to a SV supply. Tcmpnrarily laking 3 Lo nega tiv shoul~ light D. Similarly. 4 sl1ould liRht Band F, while 8 should li9,h1 C and F.. Connecting 11 lo nes>1Jvc of the S1'ppl~ should li.~ht /\ and C. If any circuit fails to operate, check WD ~olarily in particular.

~Julti•ibnitor Section "Ibis occupies !he left of the hoard, l'igure-19. 1be boaid is 0 .1 in matrix, 23 x 32 l1oles. :\i,tc that the emitter circuit tun•

------·-------------~ 0: :----; 0 .

. : • if 1!1 ·'J ! ) 1~:1· ! 'l ', ,... , I 1 ,._ ' I ;, - ~ t I I I I - 'II' : I' I I

!; . 1'° t i f : • : • f?Tf : . : o: \ • ':I: I .-, ~_., ~1-"1 : ! ~ : : : I : I I I I I .. ,- 111 1'1 I I~

'; '~I ' ' ' ' :__;' .: 1• : I I : ' I 1 1 _, •--'·-·~ '--1 I

I I I • : I f I I I

' . I I • : '--: · t ; :

--L-- -----1 -: , I ' .

f'- ' I ~ ........., ..........:-i h I 0 ! : •I I

'; r· . ~j t\i '1· ! I; i ';1-l-i . : 1 I ~ \ I ~ " ,'. :

I - \ ·"- .... ti . ~ · t<:k .., ... ,I L.! ! !- • r :

I • '- 1 L !-----1 ,,..._,., • -•-------, + x : > ' I I ! {-----~ ~

I k ~~i-1 ___ _J

: ·,~:--.::1~ . • 'I' "" ••

h: v =- ~ ~ -··· 0

:'' ·~ " f I 1', ' ... r.

~-- " L . . c.i : \

L.CLl'....:'- ~•• 1 1 • . • ~' '1 L::: ~~·~-'---~~-~

tor, and the push swi«:h wlll he couoected from P to P, •U that it cuniplotes d1c negative line.

Other points are stra.i$hlfo1ward. Where Cl and C2 are not tnsulated, they "1ould not much each other.

With 'RI to R4, CJ and C2, and Ttl and Tr2 wired a. mown, • $V or similar supply can be connected to d1e resistor supply line, and emitters (Jattor negative). Pulse• •houJd then be heard

35

In ltigli re&lstance pltones a"ross R4, or shown by a meter connected in series willt 1{4. If this test is not !l!lisfactory. check the tnmsi•ton. resi~tO< values, and oilier items here. g;iting and di~play cannot oremc if the multivlbrator is lnopcrat\ve.

Comprm~nts for :l1ultivibra1or .(Figure 19 J (ResiStOfll ~w 5%)

tll 2.21; R2, R3 33k: R4 lk

Integrated Circuit< Section

Cl , C2 2 µF (,V Trl , Tr2 2.'13706

At fir.I sli;ln wiring Lo these may appear a lie~. complex. but If carried out systematically, it give• oo difficulty. The met employed i< to uic fairly thin wite (say about 30.wg) fO< an but tlte m•in positive and neRati1·e line•, and to run u11dernea connccU011s from left Lo ri~tt, ond top connections vertically

Use hlllders for the IC$, and count pins frum I co 14 , vi lhe board from the top.

As example. tuke the two holtom !Cs, the 7404 al the left, •ntl 7400 •t the right Cut a few inches of wire, and solder it to tag 5 (If the 7404 holder. Draw the wire straiglit, and brins it up throu~ hole X. Take it across the top of the board to Y •ntl down through this hole. Draw ii scr.iight acros< to Z, and up throuslt here. Take it •erticaOy untit 1 .. el with 6 of the top 7400, do>rn through the hole, to pin (>, solder and cut nff. Similarly, 6 of the 7404 goes to 4 of the bottom 7400, and so (In. -

It is ~ential to use thin wire, and ifthi~ ;, bri.¢1\ t inned copper, it will lulder rcailily . If kept Waight arid reasoil"bly taut, no sleeving is icnerall)' required.

The 74 \12 hu pe>Utive and negative at $ and l 0. Tbe other IC• have po<iti,•c and negative al 14 and 7, as marked. Tltcsc circuit. are made with slightly SLputer wire. abllut 245w~ i• COll\'cni01lt.

Uoe thb> Oex or 30swg wire with I mm sleeving for the leads from ICs \o LE.Os. Thus 4 o f the 7404, marked B, is connected ro LEO B, 3 and 13 of the top 7400 connect 10 IBO 0 , and If.' Take e~h lead thrnugh a hole in the board, \o help anchor it.

36

Conncctioos 9.Jound tbo !Cs may be lkked olf against the following:

749'.?; I, 12, to I, 2, 4. 2. 3, 4, NC. 5 to positive. 6, 7 10 to negative. s. ~c. 9 lo J 3. l lto 11, 12. IJ, !\C. 14 pul•• input.

7404 I, 7 to negative, 2,NC. 3 to 6, 12. 4to1..E.D S to 6 6 to 4 8to 9. 9 to 11. .IU lo 5. 111012. ll to 5. 13 lo 9. 14 to positive.

7400 I , 2 , 4 lo I , 12. 3, l3 t<J Lt:D. S to 10. 6to5. 7, 9, 10 lu ncga1i,·c. 8,NC. 11 to 9. 121oll, ll. 13, 3 . to LED 14 to posili, ...

7400. 1. 2 to ne.atlve. 3, NC. 4 to 6. 5, 10, 13, to 12. 7 to negal\, ... 8, to LF.D 9 lo&. I l, lo f.,EO. l2,6to3. 14 to p<>tili>c.

The· IC< in thi• list ()(<;Uf'Y f!te same rosltl~ns as on the boa1d. l\C dcnu lcs oo conneclion. .

When inserting the IC•. assure they are the correct way round and \hat all tags eng~ properly wilh 1hcir sockets.

Tho whole can be cltecked by applying power, and clu•ing the switch eonnccred to P-P. lndicaliun• <hould change until this is released, 1-6 lhon remaining, as the ca.•e may be.

~A.. pJastic, metal or wooden c~:se ii suitahle, \Vith :u:cosnmudation forlhe h•ltery •upply, ur "ith a twin cord for plugging into a SV suppl~.

:l1

Compm1ents /or lnteglated On:uits Section (Figure 19) 1492 7404N 2 otT7400N 4 off 14-pin DlL holder.1 Cl 4nf or O.OSµ F disc ceramic capacitor l'udl switch on.Off switch Board 23 x 32 holes, 0. l iJI matrix.

NOISELESS SWITCH

For te•ting, clock-setting and other rurposes • manu•lly operated •witch allowing single pulses is use fol. Ir ~n ordinaty on-<>ff switch is used atone; multiple intermittent contacts when making or breaking, almost in~tantaneou.s. nu. pto•ide a series of pu1 ... to which the counter or other do\'J wOI re•rond.

The electronic noisi:le~ s .. Uch ill FiSJJre 20 a'<old• this. 11 u"'' two ofrhe four 2-lnpul :'\AND sates •"ailable on the 7400 Quad NANO IC. The oth~r gam may be lefl 11nuscd. ot e•n be employed for other purposes, when the 7400 is incorporated in a clock, etc.

Each ll"te rrovidu one illput for th• other, and the first pulse on moving the switch to P will step forward a binaty coded deciJl'"1 decade COll nter IC, such as the 7490, one place. Positive an<l ne~tive go to positive and ne~live of lhe equipment (e.~. SV supply). 'The lead from 3 is t•ken to the llCO fC, pin !4, nr usual iflput.

The components may be assembled on a small bo~rd, Mth the 2·way ~witch fitted to the board, or In a panel 1~r case. A spring-loaded switch can be us:ed, 0< ordinary tome or slide 2-way type.

<:.ompont1nts for Noiulm Swireh ( FigrlT• 20) Rl, R2 lk :6W 5% 7400N 14 pin dual ill line ltolder Single pnle 2-way switch 0 I In matrix. boord ab<>t1t 7 " t I hole$.

38

+ 14 llCO

RI

14 8CD

t tr'<('~

.n---..14,

'\. ( ,,

R I

• • • t

• t t t

• • ' ' .

', - _ ... -- ---· ' .

---:----· + l!....!..e,~ct

"tl!J...-i-===>'

0 FIG . 20.

TESTINC BCD DICOl>ER-DRIVER

Figure 21 will provide• 11uide to trouble "1ootiJlg a binary cod«! decimal decade count4'r and it. ••!Oelated decode>­d1iver, used In o~r•l• • Nixie numeral tube

F"or te•tinR purposes, a lii:Jit emittin~ diode L can be used in series with lU (al.lout 390 nlun). A flexJble lead with clip from RI is attached tu a rosilivc (SV) point. A brig/ii, otitT wire from the LElJ will sem~ as a prod. and the L£D wjJJ b8)1l v..l\en lhlS is IO<Jched Oil a n~g;itlve poml. l,IID polarity mu.a be curred.

!..()~Jc outputs from the 7490 BCD will be high or low, alons the I 12, 9,8 and 11 tag<. Tttese outp1tls, J-J2, 9, 8 aud l l, are connected directly to the decoder 7441 inr111s J. 6, 7, 4; Therefore hlgh·low tests made at the l· -12, 9, 8 and l I jX>inisotthe 7490 will •gr« with the

39

No. PIS p LA YEO. 0 I 2 3 4 5 6 7 a 9 P 1 N, 3 13 12 II 10 9 7 6 5 4 5V

.. r: 9 131411

+ 10 I 2

Ill 7441

.. 3 6 7 .. 12

L

1 12 9 e rr 14 74 90

2 ) 6 7 ~...---.~~~·..,.-~,..-~ •o

F IG . 2 1

couesponding 3. 6, 7 and 4 points of lh• 744 J. excep1 when the conductor p~th is defoc1ive. Thi! would indicate a fault in.wiring, foils, or actu~l soldering, which can then he focatcJ.

Wh•re the hJgh-tmv state.• of the 7490 ace followed throughout by th• corresponding inputs of the 7441 . connections from o ne IC to the other, here, are correct.

Wher~ outputs from the 7441(IC.,15 ... 2) are connected tu the GN4 :\Jxlc pins 3, 13 .. . 4 in the order shown, the numeral displayed will be 0-9 as shown. •nd will corcespoml 10 the binary appearing on the ronncctinns between the 7490 •nd 7441.

The r•ason for" faulty display can thu• he s1>u3ht as follow.:

(a) J)jsplay iequence wrong. Chee• 7441 outputs and corresponding pin numbers. (1>) Numeral($) Missing. Check :\ixie as de'Cribed. Check 7441 outputs, or £u!J.,titu te oporJting numeral, or check with HT current meter limiting curr•nt to I n1A. ll\ii will show if tul>c, connectionx. or 7441 faulty.

To check a 7441 is receiving correct h1pu t•, lhe •witch pulw<

40

(l'igure 20) can be wed. Connect it to po~iUve, negative aud 14 of Ille 7490. Out['lllS from the 7490, whlclt are also input• te> th• 7441 a• explained, can d1en he checked a• below. :I-lake one •Cl'les of tests after each pulse, ohsetving the numeral di•played. '()' h•dfcates that the LED lights when its prod ;, touched on the IC log listed, Rl being returned tu p<L<ltive as ~nllon ed.

Number Tag ShOWJ\ 4 7 6 3

0 0 0 0 0 J 0 0 0 J 2 0 0 1 ·o 3 0 0 J I 4 0 l 0 0 5 0 0 I 6 0 l 0 7 0 I 1 I fl I 0 0 0 9 1 0 0 1

l..<)Rlcal 0 is actually around o. i to o.sv at 10 to I 3mA, and lngical I may read from al>out 2.SV upwards with a meter only a(tlng as load for the 7490. Logical I is typ1c•lly 3.SV with a load drawing 0.8mA frnm the point tested.

It the!<! results are not heing pruduced by the 7490, it is either raulty, or not being used correctly (check for oniiUod lead~ wrong voltage, laj\s no t in holder ,ockets, cte).

If the 7490 pmduce; 1110.-;e results, but tlte 7441 docs n<il give lhe correct output•, it is fault)'. ot circuit incorrccl (check for "'1orts, omitted lea1ls, etc.).

Thes< tests sltoutd allow a fault to be lncntc·d in a co1111t•r, driver, or display tube, or •s.<ociatcd wirin~ wi th a. minimum nf diffw:ulty. Where more numerals are ptesenl. lests ~cd apply ool)> to 1ha1 whieh is un .. tisfaclory. It m•)' be easy to che<:k some items b)' subshtution, l>y unpluAAtng theni and placing ibcm in • !<!Clion which operates correctly.

Tho S•me type of 10~1 can be applied hJ circuits h'1ving LED 11ume1ak Refer to the list of decoder-dnver output• hy noting Ille sector. whid1 will have to be illumiuated for C•ch number, as glvcn e.:1rlier

41

Other digital codes are also employed. That for the 7492 a. follov..:

0 0000 I 0001 2 0010 3 001 I 4 0100 5 0101 6 1000 7 1001 ~ 1010 9 101 1

IO 1.100 J 1 l l()J

Tnc "Grey» cnde ch~nl!<'3 only one digit or bit at a tlnte, whik the " Exc-:ss 3" code allows complemeiuing by inversion·

0 00 11 9 1100 I 0100 8 101 J 2 0101 7 JOJO 3 0110 6 1001 4 0111 S 1000

LED RANDO.\! NUMERATOR

This is among the simpler devices to use employing a LF.0 numeral, and the 11umhe1 d i<played change. rapidly so long as a push switch is held closed, halting with a number shown when this is released. It can th11s be used in all kinds of games, as a sub•tit\otc for dice, or o!her mecbods of oblatning numbers for lhe players. Children may welcome the addition of Z4ro and 7. !I and 9, tO the 1•sual I to 6. lfthesc are not wanted, they ca111>e ignored when they •rise.

A low volta~e supply only fa required. Tllis can be SV frou1 one of the power ll•pply unus des.:nbed, and current drain i• I OOmA to l SOmA. The Numerator will also (lperatc •a tis facto foom a 4.SV or 3-t:~ ll battery, and curren! drain is \lien about 80-120n1A, !luc!uatin&as the numeral clun,µ.

Figure 22 is the complete ciccuit. Tr l and Tr2 fotm •

42

~+ -f

"' .. v i< I

:! "' :e a: .. .. 2 ~ <> ri'

"' = Q ., ~~~=Qo-co

... = rr:cn ~ ..

-N f".l <Ct lin.0,.... _ !!! ~ ~

" = .:! "'

"' !!) .:! 1

,I -" tr.

., ' "'

~l ..

"' u ID er w.

xnult!Vlbrator: providb1~ pulses as in other circuits describeu. l!ach time Tr2 conducts voltage drop"""''" R4 takes pin 14 of IC I ne(llltlve, and when Tr2 is not conducting, and wh•n the push <"itch is open, pin 14 is positive, via the limiting resi.m>r R4.

43

IC! i3 a binar)I coded decimal decade counter integrated circuit •s u'"'d for the Nixie di>plays. Its outputs ~ti~ .Jong I, 12. 9, 8 aod 1 l, llnd have been dealt with fully.

lC2 is a LEO decodcr·drlver, which decodes tbesc inputs, ~provide. Olllpnts tn light the ccrroct segments of the 7·section um numcnil. 1nus two vertlc•I sectors are lit for •ll scclou for 8, and so on, as C1<plaincd earlier.

Resistors R5 co R J 2 are each in series with one of !he 7 segmenrs to limit cur..,nt. The values of these r~stnrs can b moditied.tn some extent, to economise on current, or obtain full bcight.ne.s.• with no loss of operating life for tl\e numeral.

The numeral is a cootmon anode type, and positive is 'ho connected to piJU J. 9 •nd 14. With S..me numerals, .n lhese three pmltlve pin• may not be p rese.fll, or ma)' not be used. mark shows the top of th" numeral. It can plug in 4 DlL 14 pin hokier,"' used for !Cl.

-O:>mponentr for U::D.Numeraror (Figure 22) RI 2.2k R2 33k R3 33k R4 l k R5 to RI 2 270 ob111 •acb (see text) -Cl 2µ1'6V C2 2µF6V CJ 47nF or 0.05 µF

Hoard Layout

2 x 2N3706 !Cl 7490N IC2 7447N 8mm common •ood'c LED Push switch 0. Jin matrix ho;ird I 6 lt 28 hole• 2 x OIL 14 pin holde~ OIL \6 pin holder

f i!l'lre 23 sltows layout on top of the ~oard. Thin tinned copper wire will mo•l easily solder an<! run through the holes from point to pohu, IL is neeti.•ry to make sm•ll join I!. 11sin~ a lightweight iron. Wlth 0.1 fn matrix bnard • Jasgu bit wlU tend lo brklge two adjacent tags, and leave 100 much solder, while •tout l!JlUge wiro can C•use trouble partlculatly at tht fragile holder pins.

The multivibrator section may he checked in adv.nee , l>y taking a 4 .5V or SV .upply to emitters (negative) and ?Ol'itive line. A rapid pul~e ~h<mld he heard at C2 poi;itivc, using higll· rc•i•tance phones or .lmilar mearu1 of checking.

' ; D_r111

' r: \:"> 1 I E tC 1& ' J Rr • 1 ~: ~ t I R.2 I

I I : I .: . n

> I

' > I I

' I I I

. I I

' •

Cl C2

I ~ • I I

t , RJ r

~ . +c::!H ,, ; R4 t I

~c

i : /' ... +--

• I

: 6 IS 14 13

re-< 2

• •

12 II

6 •

• 10 9

7 8

' ' I

' I I'

/ I/ I ~r r----+'_!.-- I I

i I 1 ~ I

r-W 1 : ' : I I I I I 1 ·J

• ·> 1 l i- . .14 ,/12 II 1J\ \) 1

; IC I \

•

' TR2 li1 2 3 \ ..... , • s ~71

f I G. 2 3 . : f ,! * p I '

' +'

45

Rc•isto1s moy be miniature 1/8 watt or simibt components though 14 watt can be a~-commod~ted. )')cal with the seven output tags uf 1C2 sy•tern•liC31ly, and no erro1 need arise, £.~ 15to2alnumcnl, 14to t i , l3to1, 12to 13, II to 10,lOt 8, and 9 to 7. ~nape cite resistor ends to keep I.hem aw•y from each other, and if need Ct! place .ieevinj!: 011 th< wires in 3dvl&ll Wrong connections wm be shown by an Incorrect display of some nuin~rals or segments.

Noc all th< tags 3, 9 and 14 may be present, Ot be used for some numerat., as mentioned. The numeral and !Cs must of c<>u"e be put in their holde rs the right way.

Connect points P to dtC push-•witcb, best located on tor of the case. This can he a :<hollow hnx, •nd can hold a battery if this ls to be used. If ro, irrclude an O<J-Off •witcl1 in one battery lead. Whor~ the AC power •upply is to he employed, fit red and hlack l•ods, with a non-reversible 2-pia plug, co rake powtr from the 5 V output socket.

Numberi should change rapidly until lhe switch i.s releasctl one then rcm~iniug displayed.

SCOR~R POR BEZIQU£,.ETC.

Tl1iS forms the ~asls for ocher counting circuits fo1 V•rious purposos, so operation will be de•cribcd in det•il. Reference should be made to this section, for 1nulti-numeral Lt:O counien..

When employed for Bezique, the counter is used wleh three numerals (one perm:memly "'t 10 0, as requited for this game) and an over·llov1 indicator LED. Cotmting is hy 10s nnd JOOs, as required, and after nine !Os, !here i• nutomalic carry Co the IOOs, in the u>ual way. After 990 is reached, a further <core of 10 or higher ligltu the 'IOOO up' LED. This cun indicate the &•m<: i.s won (tW<> pack.') or may be used to indicate IOOO, to allow play up w 19'JO (sometimes three packs are used). Addition •ri<es in the usu•I manner. 'J'h•.rs if."' exampk, 390 hitd already been "'°'ed, and 250 were obtllioed for sequence, entering 2 Al the 'hundreds' point •tl•ancc< tlte score to.590, while the S •l the 'Leq$' point would nl<.>Ve t.ltc displa> to 640.

46

12 13

RESET

2 II I 13 10 a 1

IS 14 !J 12 11 10 9 I, 13.10. B, 7, 2

IC 3

6 2 I 7 8

er .s 9 IC~

6 7

C1

-s2

F tG. 2~

Unit• Numernl As shown in Figure 24th!• 3tays at 0. Six "'g:mems are wired to 0t0gallvc, and Ute r03i3tor R3 i.S'from common anode lo posi11ve, SY supply.

Where• counter will require a chang111a numeral for umU, Olis is operated fco1n JC:3 in the way sltown for.the 'Tens' numeral. E.g., IC2, JC3 and tlle numeral fonn the first section of the co11nter, am! will •how 0-9.

Fot the s,a1nc scmer, scores advance by IO•, so no mcan:1 of changing one numcr..i need be provided.

47

Noisclm Switch The 1w<> sa1cs <>f fCI, wilh RI, R2 and $1, fon11 the nol<eless electronic •witolt required to allow advancing the Ten• n111ner •• necc~•acy. Operation of this type of circuit h described eulier A simple rnechanical •wl1ch i• very liable to give •·net wnl.1cts whe11 working (not normally importan1) which w01u1I change lhe nu1uerJI incorrectly.

Sl i> a spring loaded toggle swltch, for preference, and is sn wired thaL wheil released the Ten• ~umcral ch.,.ges. To •her lhe number by one, the switch move' from one contact to the other then back 10 its ongill>l p<llrition.

Thus for the lle1ique sco1er, to emer 20, press Sl twice, and so <>n for higher score>.

Output from 1he noiseless switch, at 3, goes to input of the divider, at 14 .

.DMd"' !C2 dovldcsby 10, givi.ngpulses •t 11, !I, 9, 12 0J1d I, which pa.<S to IC3, wlitre they are decoded , and light the correct section:! <>f the numeral

Pmitwe and negative for IC2 are Sand 10. These supply lines arc often omitted in circuit•, but must of course be provided ill the octu:sl equipment. CJ is to Sllf'{lrC.s switduog tran~ientt; 'l-vhicl1 c:i.r1 upset other circuits.

S2 lS normally closed, and the counter then ope rate' normally. S2 b a push-switch or olher switch " luch an be me>menlarily orened. It then re~ets tho numeral to 0, and also resets to 0 any other numerals wntrolled from the same reset line. When !C2 has opemed IC3 bi such a way lhAt the numerilll s.h<:>ws 9, the next pul•e received •I 14 of IC2 ch0J1ge1 the numenl.l to 0 and alse> {tives an output pulse al I I oflC2.

Where a number of nwncra!J are to be u-1 on~ after anothtf tG count up to any required total, 11 will carry on·to iitput 14 of the next se..:tioo.

In this game scorer, 11 is taken lu 12 and 13 of a further gale, in order tlm IOOs may he added manually without intcrnrpting the carry from IC2 when it Kri•es.

Numeral A slight <iinplificalion ;, introduced by u$ing a common anode

48

rtsistor R4. and winns lhe setment; d1rec1ly to the decoder !CJ. This •llows .eveo direct connection• frnm !CJ to tho ft<U1\Cral. '11ie val\Jc ofR4 which i• cone.:! for two segmeots (nt1mhcr I) is noL of' course ideal when 11101~ •egments u c drawing current through the •ame re>irn>1. This results i11 a slight dimmiog, espccialiy witl1 8.

In u<e, it has been found Iha! with some IY!"S of 7-<e!DTieJll l)m, the Joss of br\i;Jttf!C.S is not S1tffic1cntly noticeable tO !>e in BllY W•y troublesome. Hut with ums Qf other manufacture, th~ loss is rather significant.

If the numeral is wired •S shown, with one resistor, and the segments dim cxce3sively when several are lllumiuaLcd, tl\en the resistor R4 should ~removed. Al Uie )Qntc lime, pl.ace a11 ind1viduol resWor in e:iclt of the leads 15 Lo 2, 14 to I I and><• on, (see Figure 22). Alternatively, te•t lhe I.FD in the pennanent ;r.ero 1LoJJ.cr frrst. connecting ta~ for variou~ nu1ncral$, and noting the display bril\f1lnt••. lf wi$11cd, the seven series mistors may he inserted originall>-, R4 being omitted. This a.ho apphc• to other numerals ln this anrl similar cnunters.

H 1111dn<ds Hsure ~5 shows the circuit associated with thi•numeral. 'J'he carry over from I J of JC2 pa.ses to I 2 and 13 of lC4. This b1verter compe11sa1cs for the presence of tl1e following irtvertcr. wJW:h receives input at!>, and provide• uutrmt at 8, for 14 of IC5.

IC5 is the decim~I divider, and IC6 opcnttes the hundrc<I< numeral in exactly tl1e same manner"' descrtbcd for lhe tens numeral. The use of R7 alon~. or frtting a rclis(or for eaclt of the soven segment•, applies here, in the w•y explained.

Input 10 of lC4 1s from the noiseless 3wii.ch oper•tct! hy the PU•h·butlon or toggle S3

The four gates of 104 are used here. Pos11ive for IC4 ~ al

14, and n0%3ti\'e at 7 Similarly, l('.5 and JC6 have positive and lle83t1ve applietl lo the lag; <11own.

The reser line carries on to 2 and 3 ofJCS, and could run on t'o other dividers, if these were fitted for thousands anti olher numbers. Herc, this circuit i• associated with the 'Thouw11.I Up' LEO.

l\1ien the hun<jred s numcraJjias 1ead1Cd 9, the nex1 pul>C

49

HUNC>REl>S ~ 101 YA7 ~ 3,9,14

2 II l 13 10 8 7 I

IS 14 13 12 II !O 9 re 6

6 2 I 7

If 8 9 res

6 ?

r

7

RS

6 5

1 S3

IC.., l2

II 13

RESET

causes output at 11. Thts could run on lo other dividers. Figures 24 and 25 combined allow counting up to 990, fot

rhc game mentiuned, with 10s by SJ, IOOs by S3, •nd rescuing to zero by S2.

If the operahnit digit• in these two circuits wu• ~<l. th< coonrcr would read up tn 99.

Where a numeral such as that fo1 hund1eds, Figure 25, is to foUow one for !Os, Figure 24, and there ls oo need to be ab~ to step forward the hundreds numeral individually, TC4 m•Y be totally omitted. Then I I of IC2·directly drive< 14 of !CS.

If the manual advance prmided by S3 wen omi!!ed, • score of "'Y 100 would mean operating the IOs switch SI ten time.. SJ must be allowed 10 spriHS hock to the posit on whiclo cnahles th• pulse from IC2 to pass to JCS., or tile hundreds count will 1101 b• automatic. It is thus beu to uie a spring loaded o r 1oggle switch for S3, •s described for SI.

A manulll advance system similar t<.> that fumilllted by IC4 may he used between minute! section and hours'sectimt of a dock, so that the dltplay can be tapidly ad•anced to show the correct hour.

()Rrllow An t>\'C1tlow indicator sltows that the count provided for by tloe m.tmerals has been reachc<.I or exceeded. J lcre, it is for 'I 000 up' or continuoyon to 1990 by playing with it IJt.

The m·erflow has to ignore the p<>nth·e going pulse, but responds to the ne~ative pul!IC, ait<l t.h.ls is done with an Inverter and $mall silicon controJlcd r•clifiu triggered by a cap•citor inpvt lu ltS f<"IC.

Pigurc 26 is. the circ11it of !his part of tlte s.:nrer. Output from 11 nf I<::s swings p~itlve at R, and goes nc~•tive • l the pulse af1er 9. The drop in collector cunenl mo\•es the capacitor

1

positi•e, and thu• triggers the SCR at Jts gato. The SC:R remains in 1h;s cootlition until the cathode drcuit is interrupted when re!lettlng the numerals. Thi• also ukes place "'hen imtlally re>etting. As a resul!, the LED remain• lit un1il anotlter ,;core is to be.storled from 1.ero. (Tiie opcrati.on of this IYpt! of device is covered in book number 8 P37 50 Proje<:l• l1611tg Relays SCR's and TRIAC's by Benianl Baba.tu (publishing) l td.).

Comnw:tlon Figure 27 is a suitahle la~uut giving ""'Pk space, U8ing a board 31 x 34 holes . • Wiring around !CJ for 1h• noiseless switch i' (duplicated "' IC4) Jt..s been shown 111 Figure 20. Wiring for 1C2. T\.3 and this numeral ¢an be seen from Figure 23 (refer to tllc previou• note regarding series roslstors). This is duplicated for lC5, IC6 and ils numeral.

Tt is cunvenicnt lo wire pusilive ·nut, with rhin red sleeving on lealh. \.!1icl1 .:an run along the top uf the bo.uil •ho~ !he /Jif)s. One negative, for 6, 7 and other returns, can run alonr,

51

+

2NS061 Sell Rll

Q />, G C +

R9 K G

{;) A A

SO V SCR

E C !! C2

e RB

2N3706 II

RIO

~s • c BCI09

RESET

F IG . 26.

near t/le bouum nf the board. Keep 2, 3 of !C2 and IC5 separate, fur the 1cse1 line.

Bling out thin lkxihle !calls for tJ1e switches, remembe1 m~ trult SJ nnd S3 iuu•I ~·connected Jn ll•c manner explained.

Two units will he required, and shallow boxes can have twin le•us tn run from• common power supply. Switches shouJJ be so arran~ tltat they a~ ea<ily operated witl• one hand. The numerals car1 come behind individual apertur~. or heh.ind a single opening, c<>vercJ v,ith uansparem material and liaving a

52

:

----··---~ • • o o 0 • • .. I ' • o o • .... • ..... • 0 0 o o o ' • • o • ' • ' •

'o

1~ ~- , 1""::·'1 ~,J L:.;_,_,_J

E] [::J

.,

. :

Fl: "---W

l- ..... . . . . . , . .. : . . . ~ •.c. ~7 •• • •••• ••• :j ; I .

r black paper mask tu suit. Faults ~re not very lihl1·. If they ari•e. tl1ey can be easily

,, loe~ised. An inconcct 7.ero will h• lrom wrong connections I here. Wrong tens displays, wurked by SJ, are most likely

C•used by emm between IC2 and IC:3, or beLwccn IC3 and the LED numeral. ff no advance ari .. s witlt operation of SI , Su•pcct JCt circulls. Similarly, if 1hc hundreds advance after 90,

~ hut nol when S3 is used, •u•pect ,.,;ring aroun!.11hese two gates

I of!C4. If the count goes ahead correctly willt I I of!C2 taken directly to 14 of ICS. the11 IC4 circuits are suspected. Failure o f

•1

the U:U 10 lighl •I 1000 after resetting and couniing froin >..cro would suggest an error in the tranioistor-SC!l sect.ion.

53

Comptmems fur Scorer for Bezique, l!:tc. ( Fiwrcs 24. 25, 26) (Re$lstors l4W 5%)

RJ, R2, R5, RC, Jk R3 220obm R4, R7 J~Oolun

R8, RIO !Ok R9 3.9k Cl 47nF C2 O.l µF 2N3706 or 6CJ09 2N5061 SCR or 50V SCR re I , IC4 7400N 1C2, ICS 7490N

MULTI-DIGIT COUNTER

10:1cr. 7447N 1off14 pin Oil, holden 2 <>ff 16 pin nIL holders 3 off cunm1on anode LEO

nun1cral~

SI, S3 Single polu charigu ov spring lnadcd swilclle&

S2 Push lo bre•k swi Ith um indicator O. l in ma1rix l:ioard.

A.I <'Plainud, this is deri~cd from lhe earliec circuit, and. i• adapted for later units. Some <lfthcse will require• decimal poiut.

Figure 28 shows fot1r digits, for up to 999~ (or 9~9.9, or 99.99 etc.). Each digit bas jts BCD ur bh1ory coded decirnal decade counter, with uul puts tu it; own OD ur decoder drl>tr,

DD

BCD

FIG . ::18.

54

wluch In rum operates the 7-segmettl um numeral. Input is to 14 of the first BCD. Output from 11 of this

BCD provides input to 14 of the tens BCD . . In t"um, this BCD pmvi<les output at 11 for input al l 4 (If the hundtetls BCO, which from l l similorly drives the final or thousands BCO •l I~ .

For a 2-digit counter , two BCO., Dl)s and their nuu~ral• "'ill be omitted. ln th~ 'ame way, omil!mg ono>.BCD, lhe 1)1;) and numeral, gives a 3-digit counter. A S·di&it or 6-digit. counter is made hy adding (lne or two further .BCD, DO and

~ nuinecal circuits. All poi.lti\'e anti negnti\'t circuits are commotl, as shown

( ead.ier. Where numeraJs are to be reset lo 1oro, the related BCD 1av,s 2 and 3 arc t•kcn to uegati•e thrOU8h a switch winch CaJl be momentaril)' opened co achieve tlw.. A common re.et line and switcti can cMtrC>l all the B(:Ds and their ·digits in this Wa}'•

Fur a decimal point, a Jk ~ries limiting mistor can be used, co l•~ 6. Sliuuld a common anode rc•;fator be used for the seven ~JOI segments, the value can be =de " P II)' placing a re:mtl)r of aboul 820 ohm between 6 and nct.alh-. lor the point only.

Mulri·Ditit Omnter Componem.< f Figure 28} Each Digit: 74901'i, 7447N, comm(lll an<>dC lliD, 14 pin .& 16

pin Dll,holders, 7 off 270 <>hin resi,tors. Ahn · Board (O. l in mntrjx), 47nF capacitor.

!OX lllVWERS

ln mme circuit.& it m•)' be necessoiy to divide •count, without a dlspllly. Figure 29 $11ow1 two IOX dMdcr., providing IOOX. Ooo 7490 11scd in this way would provide J OX.

If one decimal divider is placed before the 4-tit<ure counter, the latter will count up to 99,999 but with four signiflUJ.ll Gl)Jre$. Jn the same way, two dividers as 1rt Figure 2'J extend the count to 999,!l!l!I, but a~in with 011Jy four si~nificant fil!llres. The four •i!!-ni flcaut figures may he adequale, dependin8, on tile purpose iu vie\v,

One or more odditlonal dividecs of this kind, without dl$plays. may be switch~d into use with vun<>us cireuiu. A$

SS

+JOO +

,,.

I

1 F IG.29.

example, a process tirne1 with three numerals could indicate up to \1.99 !11!<Xlnds; or up to 99.9 3econds; or up te> 999 seconds. With tit• lc>11gec times, the absence of o!IC•ICnth or Otl(· h11ndredth figures could be quite acc•pt•ble, dependin{'. on the purpo••·

DIGIT AL STOP-CLOCK

Tlus siop.<:loc::l: or stop-watch u.'le<I with a three numeral di8pla;. ,.UJ gi•e iodicaooos to on!Henth of a .. cond up to 99.9 '°°°nd1, or to one second up to 999 ~econds. There are two ronse• • ..,Jected by a switch, acrordin$ to the purpose and length of timing required.

The digital indicating section conslm of• 3-dJgit counter, constructed as .!ready described. Each digit will employ its own dlvidor, driver, and numet•I. •nd foll details will be found in the circuits given. Two disits will give a u.cfuJ display of up to Q. 9 or 99 .cconds.

The tlming and range-selection circuit is shown in Figure 30. IC l t! the timer, with periodicity $IOI by VR !. When SJ iHk>sed. puloes ore obtained from 3 of tCI . SI is the ....itcll wbiclt is operated to time e\<ents and opened v."1on the event ends. leaviJIR the interval shown by the counter.

l'ulsesfrom !CJ are JO per sccund. When therauge switch

56

+ ! .., 1f

0

.., "'

~ \:/ ,..

"'

l. :!

... ~ ... . , ..

"' "' ... a:

N ... "' u

~ "' ·!./

"' ,.. ... ..,. ~o~ <> N ,.. "' "' - -

a: "' > "' er

57

S2 is u 1hown, the•e gC> directly to the first divider of the counter, so that 1.he first numeral operates at 0.1 <ec<>nd intervals At the same time, RS compldtCs the circuit Lo Tag 6, so Lhat the dccimat point '"mnminatcd. The DL'{llay will thus be up lo 9.9 with the 2-dl~t display, or up to 99.9 with the 3-digit di•play.

When S2 is moved tn the other range, pul<es from 3 of ICJ ~to lite additional dividet IC2, hef01e po<«ing to the counter. At the same time RS and the decimal pnint. cease Lo be c<>nnccted The display then read• ur to 99 or 999.

The di•play with tenth-second included i• •ppropii>te fot va1iuus Comp<'t;uve and other events. Thi•, however, i>1l0t needed for photo~aphic de"eloping, and vari()us nther purpmes. So the range can be S<llected as required, and be~t use made or the numerals which ~re provided.

With RI at 47k and V R J 12k, !M currect selling arose with about une-halfVRl in circuit. lfowever, tlris depends on C:I. VRI ;, adju~ted with Sl closed, 11ntil with IC2 in circuit the counter shows 60 each minute. If the supply is not well by­pa,..e<I place a 100 µf' cap>.eitor frorn P"'irive to negative on the board.

A de~ree of accuracy sufficient for many purpose• can be obtained ln this way. Where crltic.J accuracy i' required, the Q11ar1i Stoi>-Gock described latct may be aJopted. The method iri F~urc 30 u: easily 11Ceurate enouVi for numerous U>'C•. C:! may be a 2.2 µF tantalum or 2 µF paper c•pacitor.

Comµm1enr3 for Digitol Stup-Clock (Figure 30} (Reil<tnrs 5% %\Y)

RI 47k R2 2.2k R3 JOOk R4 !Sk RS lk VR I 22k or 25k linear

Cl ·C2

pot 2 µF 16V IOnF

C3 47nF IC! SSS IC2 7490 11-i>in DIL hnlder 14-pin Dll. holder SI On·off •witch S2 2-11ole 2-way 1w;1ch llmrd C:o11nler as dcscnbed

58

Roani AJSembly A hoanl 14 x 15 holes will accommodate tlte componenn, ~1gure 31. ..\ucho1 point• and crnss-ovcrs can be arranged hy using hole• •ml runnlnR leads above and below lite boar~. figure 31 shows the JC, fwm above.

SI ls mounted on the case, and also VR t, which can b.. adjusted v.~tb • 1C10W<lrlver. For convenitnl timing of ol\ort imcrnls as aecu1ately as po<Sihle, a lwin socket may be Oiied in parallel with SI, am! a flexible lead with p11sh-switch to hC'l)d in the hand can be plugged in here. S 1 then being left open.

S2 ls situat•d at nny co11vc11ient position, and can he of the 2·way •lid• type. Take ii. centr•l ta~ of one pole to 3 on !Cl , and outertags tu 11 •nd 14 cir~uirs of lC2. Solder RS to 1he <>thtt pole, using the llJll which illumiu1te'< the decimal point when IC2 is not in use. The £if1't numeral of !he counter then changes ten times a second. IUumination of the poinl •hows 'Yhon tlu• ran&• is in use.

• ~Rt ~--...--..--------' '

'"s 1 : df~R2 o• RJ ' . • f , I .... :

• 8 I 5 • I

1 IC r • ' I

• 4 I

• 's2 ... • Cl • • • • • • • •

~ll...

- --~-~ . ' . ' ' •

• • •

59

--, .... ~ .. # t ' • • 'c 2 :

14 I ~52 .

•

52 14 - ------- -- ..

• • •

CJ should be a good qlllllity comp0nent. Rotation of VR I for best ti1ning ;, least critical when mnst of the required ttsistance is made up by RI. and it is in o rder to use a tower vitlue for VRJ, and to increase JU (or •du other resiStor~ i n m ies) if required.

Take positive and negative to the common 5V su pply lines of the counter, and a lead to 14 of the first diooer in the coun1er.

QUARTZ STOP.CLOCK

For ~riticitl time keeping, the 555 adjustable timer can be replaced by a crystsl con tro lled oscillator. This generally operates al a high frequency, and Is followed by a number of dividers.

As example, it may run at I MHz. That is, 1.000,000 cycles per second. lntel\(ated circuits, each p roviding division hy 10, would progressively reduce this to JOOkHz, !Okllz. i'kH7. or JOOOH7., lOOIJ,, JOH1 and Ill<, or one pulse per 3•cond.

In lhe cry•tal cnntroUe<I time r hore, a 100kH7. crystal i• used. f our d ividers reduce this to 10 pulses per second . nus then replaces the pulses from the SSS limer. so that the J'int numeral of the co11nter can run al 0.1 second or I second Jnter\'ah, according to the range selected by S2, t>UOctly u with lhe 555 timer.

Thus the frequencies in die cry'stal cont rolled oscillator to replace the 555 are lOOkltt, l~Hz, lkll:L, IOOHT. and IOHz, while the optional divider shown 111 associ:ition with the original 555 ca.1 be in use when output at I second intemtls is wonted.

figure 32 is rhe circuit, Tr 1 beillg the crystal contrulled nscillator, with ~a,. bias by RI , and R2 as colkctor load. Cl and C2 are part of rhe O•cillator circuit. Trimme r Tl, In series with the Clll$tal, 11llow• • .,..19 slight shift ing of frequooc)'. By thi< means it is pO«ihle, if wished, tn set the c.ystal by an external frequency standard, •uch os that obtained by reception of 200klfa broadcasts, or 2.SMHz or other Slanuard frequency !ra~mission•. Thi~ Is de.it with fully in details of the radio frequency ham1onJc marker.

The •tandard of accuucy may be considered much hJgher

60

l

t +

~ti ' VI

ptt-1

.. I,;;,

.. a:

" ..

!!

~ = ~

C' ~ ..

N

~ ~-~'--111-'w:;...~

61

thllll neC<!s.sary, with a crystal intended for 30pF $Cries c:1pac11Ance, md a 30pl' fi«d c•~ilor in place of Tl. Ho .. ever, it i• quite usual to fit TI in •uch equipment.. allowinl\ fine 1dju$tme11L Titis is only• matter of a few hertz in lOOklk

Tr2 ls a buffcr·•mplifier. !Cl to IC4 a~ divider$, all u.ed in the same way. Output from 11 of IOI wtll go either to 14 of the counter, or 14 ofIC2 in Figure 30 via S2, for rhe two ran~es, as already described for the SSS timer.

Clo.,ing S I starts riming, as wi!J'i Sl for rh.e SSS timer. fC2 of Pl8ure 30 may be included on elU1cr board.

Oimp<:>ncnts for QUJJ.rtz Tim°' ( F.igure 32) (Res1>1or. 5% 141'11

RI 1.5 me~hm R2 2.2k R3 220k R4 2.7k Cl 330pF silver mica C2 800pf •ilver mica C3 IOnf' C4 0.1 µF C5 100 µI' 6V

Tin1er CoJUtructiori

Tel, Tr22N.3706 Tl 60pF trimmer XTAL JOOkHz cry$tal for

30pf $erics re•onan.ce IC! to JC4 7490

.Cry•tal holder 4 off 14 pio OIL holders Sl. bo;ird 40 x 16 holes, ctc. S2, JC2, RS ere, fig. 30

CompMents on top of <M circuit board are mown in Flgurc 33. Drill holes to take the cry•t•I hC>lder ~ts; and Tl. The posith·e and ucgath·e line.• can be 22 'WI 'I.ire, 1un along under the board. Thinner wire will be more convenient fot lead$ from lh.i1 to tho IC•. Connection are similar throughout, and can be cllccked again<t Figure 32. It may be found ea$ier to do a parlicular circuit for all JC$ at the s3me time. As example, 2, .3, 6, 7 and I 0 to negative on all I Cs. Then I to 12 with all !Cs, and so on.

Solder on red and black flexible leads for the SV supply lines at CS. Bring a simil:u lead up fzom 11 of IC4, to form the ranie selector SW1lch connection. Th.ill Oe.xiblt leads run from SJ points to this switch, descaow Ut i>:ference to the SSS timer.

A' ~ntioned, with Tl set lo ®out half capacitance. a very high degree of accuracy should be obtained, and can be checked by o])servlns the counter. Adjustment of Tl to obtain faster or

62

+

/ ' .. :! ~ . .

I 63

"' u

\ I \ I I

I

I l l I I

I

sluwer tonnirtg ha1 • very small effect, and can be c~rr!ed out as expltiined for the harn1onic marker for pr•ci•iQn tadio· frequency purpo•ea.

Second•·minutC$ Stop-clock The nµmerals have been shown '"".ding up to 99, ur 999 with a 3-numer•I display. This provides for the loiigesL interval with a gj""n number of di~ts, and is con..,,nient for readnlJ? up to 9.9 ;cconds or9').9 seconds. \\11ere sul>stantially longer intemls than 60 seconds will be timed, It fa generally more convenient to modify the circuit to indicate •econJs and minute._ Thus a readiug or 90.S sc<."n<U, as <x•mple, would read ... I minute 30.5 seconds.

This requites two numerals running up to 60, before a poise is: pass~t.I. to the next digit. and conaecliu11s are shu,vn in Fi&urc 34. IC! i.s the 7490, providing input for iu decoder IC2. which is <.'Onne~Ced tn the 7-segment J.£1) (with scrie• re•istors) as indicated. This section runs frum 0-9 nurmally.

JC.) is a 7492, and its output passes tu tile 7447 decoder IC4 .

2 ll I 13 10 e 7

" l5 14 13 12 II

IC 4

2 I 7

9 JI 12

•c 3

10 9 16 +

8

I 5

... 14

67

"

2111131087' •

15 14 13 12 11 10 9 16 IC 2

b 2 7

It 8 9 12

IC

2 3

I 5

14

+ 8

...

.60 _js• FIG.jl4.

('4

and lo segmellts of lhe IJiD numer.;il (with limiting tCSiShlrt,. Connected in W• way, IC3 and its numeral display up Lu 5, and when the numeral operated by rc2 receives a count aftet 9, the combined display ufbotl1 numerals of 5!> tC•erts to 00 and a pulse passes frum 9 of IC3 .

lnrut is tu 14 of TC!. WiLh pulses at I secnnd intecvals., ICI and IC3 count up tu 60 (00) in one minute, then pco>iding the nutl'llt pulse at 9 nf TC3. This output pulse can p .. s to another similar co1•nte1, which " ill register up to 60 (00) nl.inute~.

Jn nrder to indicate parts of a second, one divider with its numeral will be required before IC I in Fliure 34 for 0.1 ·second inlcrvals; or two such dividers and numerals, for'0.01 second intc~ .. The "'"Y in which these are ammged aud connected has beOJI sltuwn.

SI i• the reset •witch, closed tu cnunt, ret.uruing the display !o 00, and lhis operates at 6 and 7 of Lhe 7492. Positive circuits are made throughom to the 5V liue, iu the usual ma.oner.

Four uumerah can provide readings up L<> 9 minutes 59.9 second•, with five numerals gl'in& up tu 59 minutes 59 9 8eCQnll$ or 9 minut,q 59.99 seconds according to the range v.1anted.

M!nute~hour.; Sto11·dock The circuits shown alluw timing up to 59 minutes 59 seconds. 1ne next pulse will ch.ilnge the 59 second 1CJ1din~ to 00, uod pas.s a pulse to the 59 minute digit~ "hlch "ill tMn read 00. At tl\e snnie time, a pul•• is ava11al>le from the minutes section. This may go tu an ov~rflow indicolor, whleh will mow lhat I hnur ha> elapsed, and subscquen1 minute• and .1econils readings will he odditional to thi<.

It rnay be neccs.,ary to operate an hour counter, rroviding oM pulse input for this each hour, frorn the minul es scchun The simplest hours ludicator is a sinl!IC numeral, reading up lo 9, tltus allo.,,.;ng timing m 9 hours 59 minntes (plus seconds where fi tted}.

Alternntively, Lwn numerals may ht used, rc•<ling up 10 24 hnurs. (Aclual indica!ion is to 2:1:59, returning to 00.00 at the hour). Tho circuit for this is •hown lu Fi~ure 35.

ICJ and IC3.are 7490s. IC2 and IC4 are the decoder-

65

2 II I IJ 10 8 7

\) 12 t

re 3 2 3

+

I

71

2111131057

IS 14 13 12 II 10 9

IC 2

C> 2

II 8 9

IC

. 16

a -

r ICS 7 14

drivers for the 7-vesment numerals. Counting musl be so arranged that tho units numeral runs to 9 when tho tens muneral Is al 0 •nd I , but only to 3 wilh tho tens numeral al 2, with 1he whole hours dlspl&)' returning to()() at 24. lnptlt tu IC I is I pulse per h<Jur, from the minutes section, as d~bed

Three ·NAN!) 1\3tts in the 7400 JCS fl!C used to arron~e the count, and allow resetling hours to 00 by the •wtich. This is uonnally closed, $0 that 9 and JO inputs are low, output at 8 thu• being high. \l-11en the switch h opened, 9 aml 10 go high, and 8 low,~ 2 ii low, and 3 high. The l•lter point control!

66

I

h<>lh rc""t pnints of the TCs, rhu• opcnine the reset line anJ setting the numerals at 00.

The reset < .. i tch is necessary to set the hours when beginning to lime an inlen·al, and may be incorporoted \Vith themillutcs and sc~ndsresct switch, when fitted .

When hnu" are being counted, input• at 4 and $ all<>w 6 lo go low and 3 hJglt to reset automatically at 24 hours. This results front comhining the outputs of IC I and IC3 as shown.

Other parts of this section follow detaUs given earlier. Th• numerals may l1ave individual segment rc$istm•, or run with a single re•i>tnr each, as explained, when this is satisfaccor)'.

Thus lhe srop-clock {or clocl\) can have 4 numends for hours and mmu1cs, or 6 numerals to include ><cond1t. Where 4 numerals art considered adequate for the tuning purposes in .;.,....., the section 10 divide by 60 must of course be present, 1hou!fl1 no decoder-drivers and numeral• are necessary. ll will thu• cumi•t only of two !Cs - the 7490 onn 7492 willt 1 .ccond pt1lses in at 14, output from 1 l of the ·7490 lo 14 of 7492, 8Jtd output from 9 of the 7492 •l I minute intervals for. tlte miuutc section of the clock. Join I and 12 of each IC, ILS i;hown for the circuit which includes the decoder.drivers. Aho provide po•itive and ground or .ncg•live "'"'hown.

RESPONSE TIME INDICATOR

Till6 will show• compeUtor's n.-sponse tim.e, in 0.01 sea.ml interval<, to 9.99 seconds. I t is .!m!lar to a 'dri\·ing te•t' device whiclt •how• the delay between the rrescnc•tion of a ha7.ard, and the 'driver's' application of the footbr.al<e. Numerous other l••I• can be arranged along similar lines, such as threading a needle, placin~ pea.< in a •maU bottle, turning cards or coins up and in s~qucnce, fetching an object. or completing• >hurt obstade coune.

Figure 3<• shows the circuit. Tnc counter i• 3-digit, with decimal for 9.99, and rum from the crystal n.tcillaror described, with d!YJSIOtl for one-hundred pulses per ..,cond input to the fint numeral. An adjustable pulser ec>uld be used to simplify the circuit, 11< """!'racy then depending nn correct set ling of thi$.

SJA is nnnnally open, so thal digits remain ll •crn. Sill is

67

I ... 52

Fl De=~ ~=~

'I CLOC~ r og=~ ~=~ = = =

Rf SET LAMP OR BELL

rr SIA '/ Sl6L~

FI G .36. l . T - •

the second· pole of lhis switch. The use of s second pole allows any. lamp, buzzer or hell to be operated, fm111 a stlppl} of suitable volcage. Switch S2 is normally dosed.

When SIA/B ii unexpectedly closed by the 'tester' the indicating device operates, aod the counter begins to (egister. The competitor must then open S2 as rapidly as poS3!bie, leaving !he interval showr1 II>' the 1111o.iuals.

. A push switch, opening when pressed, is mo•t suitable for S2, as this will then remain closed wheu relea.ed.

For pnu.l~s. games ot task.$ taking longer, the timing can be extended to 99.9 seconds by fitting a 1·pQle 2-way switch. One E>nle transfer; the dreuit to move the decimal point to the right, and 1h• other intruduces one further 74\10 divider.

SOUND INlnATl:iDTIMER

This may be u•ed with •ny timer, but one showing minutes and seconds, with froctions, running from th• crystal controlled oscilfator, would be most sult<1hl•. Timing begins when a :iouod of •nouJh illtensit)' arises, and will nonnally be initiated by a blank ftru1g Startin~ pistol.

Timc1 circui.ts to operate the n~merals have been shov.~1.

Figure 37 is additional to thi• part of the equipment, and slarh timing by autom•ticilly cloomg the re<et line.

A small 60mm speaker of abuut 15 ohJll impedance acts as lhc $0und recept()(, and is coupled lo the firs t amplifier Tr I by the capacitor Cl. Rl provides b ... .., current here: Amplified signals arise ll<:mss R2, .nod go lo Tr2 vi• C2. Rectification by diode DI moves the base ofTr2 uegaLivc. This is a PNP tran&istor, so collector current through VRI rises, moving the g•te of SCRI positive. Titis trigger< rhe illlcon controlled re.:tifier into conduceion, am! it ren1aiM in thi' sl.~te so that lhe timer continues to operate.

YR! alluw• adjustment of scmitMty, and this must not.be too hitlh, elf other sounds can trigger rhe SCR and nan the lln.er P"4ition the microphone (sp«lker unit) f•cing the firing lnc:anon, with senoitivity to give reliahle working.

The Lf.O and series resistor acl .s an 'on' indicalbr and pasi current to hold the SCR in conduction.

' ..

I STOP

c~ocx l------__,.__o_o_._o~o-

Al

r!G. 37.

69

VRr SCRI K

Kr.:f '\J/4

+ l

!falling of the timer can be by any of the method• shown, and not resulting in altetations to the count d~ to imperfect comae! ot other defects. lnt•nuptonn tn the countillg chain is sau.r1ctnry pnmded it i~ at a Point of 4uite hl8h frequCnc)'. On the other hand, interruption by a slid• •witch, at the c<:1unter input, woul<l usualli• re<ult in a random jerk ahead of st\'Cral figure», due to the imperfect contact rle1<:ribc<l cl•ewhere. An elect!MIC 1roiselcss •witch, ""'h as 1hown, may also be adopl«l to •lop the count with its display remuilting illuminated.

Components for Sound !11ilit11ed Time> (Figure 37) (Resistors .S% '4W)

RI 1.8 mcguhm R2 4.7lc R3 270ohm R4 lk YRI 500 ohm ( 470 o.tun

suitable) Cl C2

O.S µFor 0.47 µF 0.5 ilf or 0.4 7 µF

Cl Tri Tr2 DI SCRI

100011F 2N3706 2K3702 OA90 elc. .SOY IA or similar tyre

2*1n orsimilar 75 ·80 ohm speaker.

LIGl:IT OPERA TED COUNTERS

A coumcr operated by interrupli-011 ur • light beam has numcroo• applications. TI1e circuit in Figure 3R is so arta.aged that tile counter ad\'an.."CS by I uch time light is shielded from the Ugl\t dependent rC10istor.

Tlte1WR lm a typic•l resislonet of some lk to 3k or •o when lit, am! I OOk or more when nOL illuminated. \\1ten light fall• unit and its resistance is low, iL hold• the base of Tri negative, so that collector current 1, negligible, The voltage dwp In R2 is small, and input t9 14 of the counter is high.

When the light path is intezn1pted, the LDR resistance ri.es to a high vttlue, and base current via R.J and YR I cau" coll<ctor current to flow through R2. so that point 14 mo,·es n•!Jltlve, ad,ancin.~ the count. The e<>unt is not further od"anud by restoring light to the LOR. YR! allows adjud· ment of scn<itivity, and R I is to avoid darn~e to Tr I by ca.n:lc:si: adjui:t1nent.

Tri Fl~vre 39 the circuiJ i• •n nl'ranged that tJ1e counter

7d

l

+

A2

t-~~~~~~~ 14 ON COUNT EA

TR I 2Nl704

E C 6 e FI G. 38 .

ad1111nces 1 each time the LDR i• iUvmlnated. Here, when the LDR is not lit, it~ resistance ii high, so VRI m•rntains the b••• Mgath·e. When light falls on lhe I.DR, its re•istance fall$, providing b • .., current, ro that volta~ drop in RI moves 14of1hc counter nega1ive. Nole that in thi• case tJ1c counter advonces wllen light reaches the WR, hut the c.:.uo1 doe' not

LDR Al

14

TR I

VRI 21'13704

I" I G.39.

71

ad•ancc wh•n illumination fails. For the."' cireuil$ the ORPI 2 or similar LOR wUI be suitable

with 211:3704, 2N3706 or DCHJ<J for Tr I. In Mg\<!~ 38 RI is

33k and VRI I m~hm lineor, with J.8k f<ir R2. In Figu.e 39 VRI is a 470k linear potentk>mtter, and RI l .8k.

ln each ca$e a higll resistance vollrncter may be clipped from Tri collector to negative lino, lllld VR I adjnsted untd suitable high •nd low reading,' are <>l:>tni.ned with the iUumbralion which will be present.

Ymons Counter Thi• will show how many ti1UC• a ll$l•l beam across a doorway h:ls been Interrupted, and may be used where this gives acce» lo. demOflirtra!ioo, sepautc jlllrt of. mop, etc. Operation is lust critical .. 1tcre gener:al illuminatlOfl of the 1..1)}{ is fairly subdued.

Flt !he LDR in • tube, with the c<>unter, one side the door· W&)', and directly OPi"OSite have a ~moll, low· powered spot­llf!ht, or slmila1 means of illumination directed at the WR. With VRI suitahly adjusted, the counter will •dvance by I every llme an opaque object cornes betwe~n light sour.Ce and WR. Avoid any •et ting which results In the counter respC)ndlng to flickering uf the lisJ!t at mains frequency.

A .~numeral dtcim:il type counte1 will rcgiucr up lo 999. and a manu3l reset switch v.•ill allow rClutning this to zero as -3Cy Placing ooe dcdm:al dlYtder. without numeral. before the counter will allow counting up to 9990, with display to lhe previous ten .

Revnh•tion Couuko" fllr~t interruption uf the llg}lt beam by a rotating parl is somc!lmcs possible. 111e beam may pa$S through the holes of a Lnhe foccplale, spoke ~paces of a flywheel, or something of this kind. A •mall ligllt on a flexible cord, wilh tube to direct the beom. will be convenient Needless tu say, care is exercW.d to k••P clear of mo'1ng machinery.

The l\nal count will be dt•id<'<ibv the number of interruptions per rc•·vlul!on -· as uamplc, six, for a f>.spokcd wheel. Where tht tcsl will often be niode <>n one machine, m with one similar set of conditio•l!, an extra IC (to JiviJc by 6

72

l

or ., requlred) may be placed bctwCtn Tri •nd the counter. Fut RPM In the simpl .. t manner, employ• watc11 .,;,h

"""'nd' hand, and a noiseleu switching i;y<tem, operated by a push 9ulton, which cm be held down for I minute. This gi•es easily cnoug)1 accuracy for most such purpmes. fl also allows expan!lon of the reading, by timing, as e)(Rrnple, for 30 seconds only, ind <louhling the count to obtain RPM.

For automatic counting, a timing gate Is used. Thi• opens for one minute (or ge11erally such shorter in terval as may be selected) and thus Ute counter regh ters for a kriown period . from which the RPM may be derived . .Such a method becomes e.,ential for very brief timing iatervalJ, nnd will be found in th• section on frequency counleis.

Where hglll C\nnot be directed lhrou!/1 •rotating whe<:I, the same result may be obtained by rellectlon from m area of white paint on the rim of the wheel, or some other con­•·cnicnt p<>inl The light must then be directed only at th.is, and the IJ)R is shielded by a tuhe •O that only 'etkctcd light ;, picked up. J( the whole surface reflects, paint an area •natt black.

6-0igit Frequency Cou111er A frequency counter can best be assembkd u a number of uniu, whicf\ may be tested separaccly. Thi< avoids having completed 1he imtrument, aod pombly h>ving son~ obscure fault whlc:ll oould be difficult to locate. It may be divit!cd into the following section, as a matter of convenience in conlitructic)n

6·Digi1 Co11111er. Thi• will allow cou11tiu~ up 10 999,999, and with a cent rol decimal point and kllL operut!on, allows reading auilio frequencies and r.il.io frequencies over a usc(ul range. frequencies will be shown directly. Titus 000.050 will be 50 hertz, 000.862 is 862 hertz, 001.500 is 1500 hem, or I .Skfu, wot! M> Qn, up to foil capacity. Frequency coverage can be .. tended by moviltg the point or changing the uugi: by• multiplier, for ftequeru:ics h igher than 999.9k11'. A I.ED numcrol ctounte: is.indi<:•lcd, but where a countei hos been made with NtKie or other numerals, thi• wtll O?erate in the san1c way

73

•

CWck. This cnntwls the gating interval. Thus, if the interval is I .ecun<I, pulses are counted for this pcriud. AS example, 1f the C-Ounler section registers 0 13.000, during I seccnd, the frequency is 1 JlcHz, or 13,0UO bertt or cycles per s•cond. Oth•r ranges may he ohtained by ~hanging the gating intcn·• l. lf this were reduced to one-tcnlh of a second, onl)· 1300 pubo• would be counttd. So the range ha• in effect been multiplied by l O. ff the gate ;, open for longer or.hotter intervals, the number of pulses counted will he greater or smaller. A correct interval is thu$ necessary , and this is ohtained by u~ng a cry~tal contcC>Ucd <»cillator ot clock.

Gare & Rciet. The gate is opened and closed by a dual J K flip-flop, so arranged that one pulse rriUCT! it open, and th e next pulse trij!gers ii clokd. The inpul .;gnal, whicli u tu he countod. can thus pass lo th_e cuwiter section for I =nd.

'Inc counter ha. to be reset to z.cro after each display, or the counts would add one to lillOther. Tilis is arranged by opening the reset line then closing It bofore lhe count begins.

111ese method• of working pro vide a re!IO!ution which will normally b•.accurate to l Jigit .

Amplifier and Shaping. Tu allow vartous inputs to be Jcalt·with, an input amplifier is usually incorpocateJ. This raises lhe ;ignal lc•cl• of low-level inp\lts so tlla l ihcy are ahle to operate the cuuntor. V.'hen a fairly hiJ:b dU!!Jee of amplification is pruVlded some meaits of a ttenuat ing strong inpuu is usual, or bannonlc am! other features of the Input may add \o the count. These CCO'• lo !>e recorded as the input is attenuated.

01unter Se<:tion Figuic 40 is• block diagram of this. h will require •ix LEO numerub with holders, sL~ 7447 decoder-driver. with holders, and six 7490 decirnal divider-. with holders.

Connections from the 7490 to the 7447, and from 7447 lo the numeral, have been shown In earUcr circuils. Each 7490 receives inpot at 14. f .acll 7490 (except for the last numero) provides output at 11 for the next d ivider.

F.ach 7490 hai; 6 , 7 and to grounded to negative. At c""h 74?0 2 ""d 3 are connected 1ogether, and lo 2 and 3 of the next 7490. Thi• is the reset line. cummuu tn all •ix dividers. The

74

... I ... w ::> "' + ... "' ...

:!: a: z "' "'a ::i "' l3 ..J .. ....

-== - t-- -..... LO 01-= .I ' I

t t

,___ i- co f-- "'

..__ "'

----== "' - "' ·- 0 0 0 ~ == --c•

0 -.... == .. .. ,___ .. l .._ O=O=°f-

>--- .

ro=o "' ..__ "' ·- -==.

l .., "' - 6 a: ~ = = oL. .... l!: ., 0 .. ..__ ..,

0 "

..._ B=°= l :.: > -5 ... 0

"15

counter opetalC> when this line u sw11ched to negati,·t With this switch open, all numerals i.ndiA:•t• rero.

The decimal 'point of the third numeral is permanently lit (pin 6) by current fcom a 4 70 ohm resi$tor. Positive a~d other supplie• for the 11umerals and !Cs are arranged in the way previously cxplalned.

Ths section is comtructed 011 0.1 In matrix board, a.nd needs only f0\1r external connecting pouus. These can be culnur­cnded flying le•dS. or pin• on tl•c !>ourd. They are posUJvo, 11eg~tive, r~set line, and input to 14 of the first or unit$ divider. ·

Hand wiring of a counter of thi• kind is grcatl)· speeded by using thin tinnc<I copper wire with• few colnurs of very small di•meter lnsufated sfCC\'ing. rirsl provide (lOSitivt and ne~r1>e btl$·bars of :!Oswg wire, for the res lt is then best to reproduce the wiring of one section for all •ectlons, point by r oint. As cx.mple, connc<I I to 12 at each 7490 •nd m11 the wire on to 7 of its 7447. Ct'lru1cct •wire to l l of each 7490, p113s through sleeving to 6 of .. ch 7447, •older and (Ul off. In this way the· correct duplication of circuits is eased.

1ne finished board can be ciiedcod by remporarUy connecting • 5V supply. •nd noting that all 11umerals are zero until the reset line is.coo11ccted tt'I negative. An input may then be taken to 14. This ca.n he from the 555 rulser, at low frequency at lirst to ob•erve correct working of unit< and tens, then 3~eeded up to allow checking of hundreds and thousands until all numbers reach 9. A fault at any numeral nuy he tra<cJ tu an IC, connectio11s, '" numeral, as explauied eJ,,..,nere, and !Cs n• easily tC•ted by substitution from a ••ction displayins correctly.

aock Figure 41 is a block diagram of this. Here, a 1 '.>1H7. ccyual controlled oocillator i< fitted. Sub<equtclt decade dividers reduce this frequency lo JOOkH,, IOk!L<, 1 kH,, 10011< •nd I H1., or 1 puJ .. per scconp. Pulses may he taken at the rate of either ten per second, or. one per sccnnd. Tl1esc go to the gate en.1bli11g ••ctiou, opening the gate for one-tenth "cond, ur one second, for·t\\'O frequency ranges, a~ mentioned.

This section uses a crystal OSCJ114tor, as already shown, and

IKHZ IOOHZ IOHZ f Ht

OSCILLATOR

FIG .41 . GATE ENA&LE _j

five 7490 deaide dividers, with holders. Ground lo negilllve 2, 3,6, 7 and IOofeac:h 7490. Take input to 14, .andoutput from 11. Aho join l and 12 at each JC . .\ posWve •upply Is required at 5 of e•ch. fly-pass positiv~ to negative with a 0.1 µfl capacitor.on the board. Additional information on such a cry•tal oscilla tor, with wiring, will he found eadi~r.

Th• clock can be checked by means nf the counter bwrtl, by takins JOHz or II tz out put to Che board input (1 4). Join Politive aod oeg;ittve lines. The count should advance al J 0 or I per second, accordu1~ lo input frequency •elected.

'Jhe ciystal can be •el exactly to frequency in rite w&y

explained for Che ratlln frequency m•rker. The posf>ibility of a plus or minus error 6f I ari~s wieh

frequency countets because there is no synchronisaUon between the incoming pulses to he counted. and elod: pulses. This i< normally ignored.

('.,,re & Reset Two !Cs are used for Olis section , Fi~ure 42. The 7400 provides a noiieless initialing swicch and gate to pa.- incoming puh••· TI1e 7473 is a J -K fllp-fiop ananged SQ that the gate allows p1~scs to p:m to the counter for one lul1ins interval ooly, upon uch occasion • re~ding is taken.

Tite operation <lftwo NAND gate• In the noiseless switch circuJt hos hccn d•seribed. It control• S nf rhe 7473. Clock pulses at I sicond intervals.( or some other chosen frequency) ariivc at 1. When tht 7473 is set by that half of the 7400 forming the noiseless switd1, from I I, tl1e next pulse al I of

77

IN ~3 'i f I C.4i. 2 1U 7400 .-

12 7 4 CLOC~ 7473

s 9 , .. 10 II

+ e 13 9 II 14 7400

4 5 10 12 ~K l\CSET

Jc '5K -........... ....... ~ ·····

•

the "/473 ~ves output •t 12 which allows the &ale to conduct when pulses arrive at the gate input I of the 7400. These pulses, of the frequency being measured, thus appear at 3 of tilt g•tc. Wl1en the next clock pulse auives •t 1 of the 7473, oot put rrum 12 clore< the gate. ~s al 1 of the 7400 gale nu longer • !'Peal ~I 3, and the count ll<>P'-

A fre.iuency reading is ubllliuc<l by pr.,.sing and releosing the pu~h-,witch. The [!Ille then open< ot the next clock pulse, the counter operates, and the gale closcs, leaving the eounl displayed.

As numeral~ need resetting to 7.trO bet1NCCn count111, a.:1econtl pol• on the rush-switch i.\pcus tltc rcsei line, w that this h ohtained automatically. A 2-poic spring loaded leaf switch is mosc suitable, anu contacts are bent so that the rese1 Hue i$ cumpleted b<fute counting •tart$. It should be nottd that the cunneetinns front the noiseJess s-..,iteh arc ool reveriihle~ a~ if the g•t• ls enabled while the r=t hn• u open, no iodk~tioo can orise. R•,·ersed connections here can oltn cause differeot count$ each lime, <lue to the ro<et line only l>eing closed for• part uf the counling interval, which wIU in turn depend on huw

78

l

the switch Is operated. A mechanical 'witch from 5 of the 7473 un he re:i.'On•bly satisfactory, b11t can !esult in chan8ffig counts with rile same frequency, due tu s"itclt imperfection:;. as explai<tcd elsewhere.

The•e twn I Cs may be fitted to a board which will also cariy lhe mput amplifier. 'l'o test thi• i;ection, connect 1 •ecund pulges from the clock bo•rd to 1 of the 7473, and take 3 of the 7400 jtate to the iJ1put 14 of the count.r. Apply a suitable i11put - such as that frnm the 555 rulser shown later -LO l uf the 7400 g>te. The counter should then be seen tu run for I s«.ond, after the switch is pressed, and should di<play the same number each time (plus or minus I) unles~ the ioput frequency changes (due to temperature chan~s, etc.).

T11e switch should be located f0r easy operation, when the Clltln tcr 1s In u.c. ·nm mclhod lea•~• st.able reading, which will remain as long as wanted. The switch ls rre.~d each time a new •••ding i• required. For automatic operation it is necessary tu have a m11ltivibrator (F'igure 44) or other mean• of comrollillg the 7473,. giving S\1it•blc repetitive count and display tbncs. To provide a continuous <ll•play, I.he count has to he taken intt'l binary Ct'ldet! memories or !niches, then to.<hc decoder-drJverst with a contrul section which initiates each acUon in corrccc sequence.

!'or two ~~nges, a :!·pule 2-way switch can be used to take clock p1dses 31 I second and 0.1 second 1111ervals

Amplifier A simple amplifier whicl• will pruv1do a •ensitivity of arproxi­mately 0.5 volt i< shown in Figure 43. VRI allows attcnualion of great.er Input; where necessary. Th~ Lr3nsisrnr collectt'lr swings negative wl1cn the transistor ;, conducting. Pulses only pass through the gnte to be counted .wltea thll ii Optned in the way described.

A •crecncd lead with earthing in the usual way is generally neces.1ary tC'I avoid n1ains frequencies becoming a::ssociatc<l with the lnput. F'or high fre11qc11<1<s, •tray capaciunces must be kept down, both in hlyoul llll<i lcst lea.I, nr sensitivtty falls off f rum the :dlunling effe<:t introduced 1n this way.

An increase in frequency, beyt'lnd that with which a counter 1s normally able to deal, i• usually provided by means of a pre·

l'IG. -4 3 · - -E <: B

e:i R2 R3 2201< f.SK

Cl RI 0- F 3.9 J(

~·-VR J 10.K 2N3704

+

I ON G"TE

(7-400)

s.:aler, ff required. Typically, this ~an cumi•I of a sirtgle tfecade divider, able to operate at high frequency. It is fed from the frequen~y lo be nie•s11red, and its output passes Lo the C()Untcr. As it divides hy J 0 (or oth<r chmen figure) all the frequency counter indkal!Oo\S are multiplied by JO. · lncrea~ se11$11i•ily. where wanted, u obtained by \J.\ing a further amplifier, and a Schmitt trigger is frequently placed bt lht amplifier output circuit, before tJ1c gate. This Is operated by the sine and other waveforms present. A variable attenuator {VK I) niay be teplacod by a switched re•i~t<>r attenuator, with a number of input levels.

Where required, OC iwlation of btput is obtained by placing • capecitor in series with the input circuit . This can limit the low flequcocy, or prevent very l<>w speed COllnt•. Diode limile" may be present acrns• the Input, tu clip this to• pre· set ievel. Various methods of p1<:ividing compcn$lltiun for chaitges in frequency can aho be prcivided.

l::rrors in counter readings are ai.:i:.1 likely to arise from external source>, &uch as pick up or leak·througb of mains frequencies or nrong RF or other freq11cncies. Overloading may •llow cith~rwisc in<ignificant harmonics to regmcr. lmuffkient level of inrut rnay result in reduced count• if the level varies, only •cime pulses being f)f sufficient magnll\lde ro O~t>tc the counter. Very high mrmeral indications, with nu input, usually indi<>llt instability in 1he •mplifier section,

80

which 1a generating oscillation• which pass the gate and operate the counter section.

DJGrrAI. SIGNAi. GENERA TOH. Tilil us .. a ~~>unter with fh« numerals In read 11p to 99.999, clnck, 113te, and gale operating circuits with inpul amplifier as shoWII for the frequency counter. To enable 1he gate to pa<> the signal from the signal gencralOr "'ction in order that the freq~ncy can be displayed, 5 nf the 7473 must go low, then the count continu•s for one clock pulse when 5 goes hiVi. Thi• i• initiated by one-half of the 7400, u•ing two j!!att¥, u~ 1;how(\.

Automnic display can be provulod l>y means of the muJu • .,boator in Figure 44. Cl and C2 are of dissimilar value. The col!ecLON of Tr I and Tr2 driYC the 7400. l'uinl 10 goes l\igh t>rietly, and so does the counter re••t line, for return lo zero. At this tlme 12 is low. Point IO and the reset line arc held low for a longer period. This allows 1/te 7473 to open the gate at Lhe next cJcock JIUlse, and do>C it at the following clock (>Ulst, the C()unl remaining displayed.

Jn use, frequencies are <lisplayed foe abour 2 to .3 seconds, this bemg rep<!atetl automatically. The C()Un t-up for 1 second p<!rlOO• Ii r••dily seeii. but for 0.1 *"-"On<I or shorter intervals can sc~rcely be seen, and neither interferes with the easy

12

RI 10

RESET

€ c " C2

e>

81

reading of the oumher shc)\vn, Nole 1ha1 12, and JO (with reset line) are nol reversib le.

uni~ Cl and C2 "1ould al!" be eiu:hangcd. RI and R4 may be 1.Sk each ln rarallel o.ith the llimllar ''"'"tors in Figure 42, if tin• auto-display is added.

Om1prmtnt! J(ir F;l(Ure 44 (Resistor! 5% %W)

R, r' \{4 750 ohm R2, R3 33k er 47.o µF

C2 (;3 Tr! , Tr2

2µ1' 470µF 2'.\3706

With the rnult:ivihr.ior contn~hng th• counter, resulls U.ould be the same as when the reading was obtained by inear\$ of' the 2.way pu;-h·switch, ex..ipt lhul the)· are obtained, displayed, and cancelled automatically.

The upper frequency limit al which such a counter will operate depends larseJy on the first decade divider. Where a hi~h frequency i• required, this is generally a sclcclctl JC, an IC designed for HF pucposes, or a pre·!IGaler as described.

Where the waveform is not imp<>rt~nt, rJie 555 pulser can be arr•nged ro operate up tu about SOkH? by employing a S\vitch \\'ith mnre \\'ay~ selecting capachors <lo\vn to 2 .. 000pF. The o utput 1nay operate the counter for l~quency d~lay direct!)'. or m•y feed life amplifier lllrou~ a resiuor of Kbout l!.2k.

j\udio Oscillator Fl&uce 45 ls the circuit of an adjustat>l• audio oscillator

able to op•rnte over the frequency ranse of approximately 15 H1. tn 20kH'1 .. Output i• amplitude ' tabilisetl, and of sine wave q uality. Operation is from a 9V supply. The counter input •mp!ilicr is fed ,;a a series resiSl<>r from th~ point C, the input amplifier polentiomc ler in l'i~ure 43 not being requircd

82

+ ~0VP) : . ~ Q w 1i1 a: f- ,,.

"' "' a l > "'

'!! ~ .,, t10 ,;

u

= "' ,...

"' a: >

_J. "' u CIC + ... 0

(I'.

... " ...

.,, a:

"' 0:

"' .. ~I a: ii "' "' ...

83

Components for Audio Oxcillator(f'igure 45) (Rcsls1ors S\'M4W)

RJ, R2 6.Rk R3 J.2lc R4 JOO ohm R5 Type R53 1he.nnistor R6 61!0 ohm R7 10 ohm R8, lt9 l.Sk RI O !Ok Rl 1 S.2k VRJA{B2-g11ng !Ok linear

potentiometer

VR2 Lk lin<oar potentio-m<etn

CJ 1000 µF IUV C2, CS J µF C3, C6 0.1 µF C4, C? lOnF Tr I, 'fr3 BC! 08 Tc2 llC1&6 SIA/A 2-pole 3-way switch. Board, etc.

RADIO FREQlJEr>CY M~RKER

'Th.is uni! .uows exact calibration of a radio receiver, signal generator, or the variable fcequoncy o~cillaror of.a tran>ittitter. l'rovision i• made for marker ~>ips at !MHz, IOOkHz and lOkll< intervAIS. up to 30MH7.; nr higl>ec with • scnsi1ive receiver.

In u .. , the l'.1-111' pips will only be required with equipment whlch IS bAdly out of adju$tment. or bnme-buill apparatus where the frequency is almost completely unknown. The 100k.H7 plps-appe~r at one-tenth inte1Yals, md are of con­:side11ble use. Fot bandsprud rece!Yen or Vl'O calibiation, the !Oki!• pips allow division of lOOkHz secto" into ten.

FiRU!O <16 i.! the circuit, and twu g•tcs of the 7400 ICI function as oscillator, 'Operating with a 1 MIU CJ)'St.:I. The r°'i•tora are tu provide suitable operating C(lnditions. Trimmer Tl , in coaj1.mclion with CI. allow• slight pulling of the crystal frequency, so that this can be ••I by means of an external standard, such as 200kH7. radio t>roadcasl•, or the standaid frequ•ncy tranStnissions on 25MH1, 5MH7. and othe r frequencies.

Th' remaining gates of this IC aro ulOd .. , huff el'$. IC2 provides di,ision by JO, and thus IOOkHt output, while IC2 •&aln drvidei; by 10, for the !Olcfu ourput.

Switch SI .. 1ectHhc lMHz, IOOkH'Zt>I IOkHr. signal, ., required, and uses !his lo dri•e Tr I. Output i$ obtained at the en1itter, and •ign.:I lewl c&l be adjusted by means of VR I.

84

.... :r ... -:l1 a: -- "' ·2 " ,.. 0

l:! a: II..

... u ii

Output U><: For many purpC>SCI, 1uffi~ient inrvt to the rec•iver will be c>btail>ed if a .t1or1 lead from the marker output sockc1 is roo

near che atrial sockec of the receiver, or near• short wire h1kcn ln th• receiver socket. The usual ••rial is disconnected. Coupling may r~ adjusting to suit cite receiver sensitivity and the order af hamtonics, which grow ixogressively weakc1, unhl tb<y can no longer be detected. VRI ean be turned back where sign•h are too strong. The usual inoxp•nsive potentiometer .,.,;u not completely attenuate •ignals, especially at higher frequencies. \\~1cn Sl8Jt.als llle not too •trcmg, the oUtpOI lead niay be connected to I.he receiver.

The !MHz marker signal• will be heard at !MHz and mulllplc• - 2Mllz, 3MHz, 4~1H>., and so on, throughout the receiver tuning ranges. Scales or ..Uals can Ihm he marked at I Mf11. intervals. With horrn:·buill equ!prn•nt of unknown cove1>1C, one frequency has to l>e identified on each wa...,band. by rc(l!Te.nce to a broadcast Sll hon, 1ma1cur baud, 01 similar means. The .l ~tHz oiarks can then be counted up and down from thi•, and nun1bered according lo frequency.

The lOOkHzoutput wHI provide 10 pips r er !MHz sector, and will be appropriate for calibration over many general coverage ldgh frequency ranges. The l'Ol<Hz marker signals again divide the.e into JO sectors. Those will be too clo•e together for many general coverage receiver•, except those with bandspread cuning.

Tunins of the recei;,,r oiay be noted by m~s o f a bellt frequency oscillator, which will usually bl? available a; exact calibru i0<1 of thk l:ind is most likcl)' lo be wanted with a communicat1ons type rccci•cr. A tuning indicator can also be used, and may consist of a mu\f.1.rangc meter'clipped on to re-ad the :inode. colJector~ exnitter, or drain cu.rrent of an au1omatlc volume conrcolled st•~•·

Cty&IAI Trimmint An extremely high degree of accuracy cru1 bo obtained by pullhl~ the cry< tal into frequency with an external source. To do !his, u•• an aerial with the receiver , to obtain reception of the standard frequency tran.mriS>iOl\s on 2.5MHz, or receive 200kHz traiumiuions. Differcocu belwtcn !be 2SU\ or 1nd harmonw: of l OOkH>. and t!tis signal will l>e heard as a growl or flurtcr, which will fall in frequenc)' as TI is adjnsted in the correct direction. Por best resi~ts ind easy adjustment, •ign•ls

86

fre>m the station tuned in, and the marker gene1acor, need to be of roughly similar strength, or at least not so different that on• sw1mps Ute other

VFO Collbrati<.>n Tn calibrate a VFO, couple the rnorker uutput •nd the VFO to a rec~iver. Tune in a ma1ker harmonic with the receiver, and t11ne the VFO to 7.ero beot with this, and calibtate I.he VFO di•l tu suil. Continue a< nece!.1ary. A.• example, at 3.5, 3.6, 3.7 nnd 3.8~11z for the SOm band, suhGequently fillii11:in wiU1 I Ok Hz points.

Accuracy of receiver tuning doc• not influence calibration. The r«e1;er is merely used to rompare tljc fsequcncies of the VFO •nd wonted l\ann<>nic.

To cahbrale a signal generator, proceed in the same w•y, except that marks will generally lie al "'<lCI poincs, exct1il on low frequencies.

COirOCt calibration will allow lh.e cuy location of Mgh frequency bands, s~ations using knnwn f're4ucncies or wave· leoi:ths, etc. Trimniing and alignment of calibrated receivers may be directed toward• securing the best agreement between di.ti readings and actu•I frequencies throughout.

Ci1>npo11e11r~ for Radio Fre.q11ency M11rlcer ( Figu"' 46} (K.csistors 5% ~W)

R t 1.llk lt2 220 ohm R3 S60 ohm R4 220 ohm RS 470k VR I J k linear pot Cl 22~>F CZ 220pF C3 220pF C4 0.01 µF

!CJ 7400 IC2 7490 !CJ 7490 3 nff 14 pin U!Lholders TI 30pF trimm~r Tri 2N3706 SI Single pole 3·way I MHz crystal & holder Board, elc.

87

VARIABLE SSS PULSER

~1itn making or testing a counter, whether decimal, or for seconds, minute• •nd ho11ts, some f•)(nt of rapid checkul~ i• useful. A variable pulser, using the SSS integra~d circuit, will be convenient for this. !:'our ran~cs are fitted, for approx!· mately 1 puhe per 20 se~onds to 3Hz, Jlfa to 160Hz, 160Hz lo S,OOOlb, and Sklfa to '.!OOtHz.

The slow puls..• anow o)lscrntioo of the JCConds or r. .. 1 digit display of• counter or tinier, and indiYid11al tc•ting of various digital circuit points for ltigh and low, if required. To speed up cltccking in tens, hundreds and other sections (or minute or hour sections) pulses can he •reeded to run the whole counter al a ~really increa.••d ra~. In this way, as example, tho whole aumeral "'quenccs ur a 24 hour clock can bo observed in a few nllnutcs.

Figure 47 shows the circuit. II ma),. be operated from the same SV supply <>peratiilg 1!tc counter e>r timer, or from a

+

Vf\1

RI

74 6 R2 l

555 Al 2 6 s

SI

~ a13~4 cs

OP -T I 2 3 A

UT_ FIG . 47.

•1.SV {3-ccll} ballcry. If a scparnle supply isu>Cd, join ne~at1••s (>f pul.er and cou11ter m timer.

VR I provides adjustmenl of fttquency. SJ selects ooc of a range of thnlng capacitors. The lo~r wluc:s ptovidc the Jo"Wtr ci:ttc~. ft is, of e<)urse~ nu( e,,~nhal that the rJ.ng~ be exactly Oli: 1nentioned, so other capaci:tC)r values, or modllicaUon to VRI, would be pornble.

Oulpul i< from 3 of the 555, via• rcsislor which limits fau)l turnsnt in the event of a detect ()T \vrong connection.

The few components are read11y wired on a small O.lin matrix huarJ. This, .... and Sl and \'k I. can lit inlllide ~ ca1o;e or box. Red und black flexible leads, with small clips, will allow easy connecting up to tlie power lines of the timer or counter which i• to be checked. 1lle output lead can he fitted .. 1th nne nr the miniature insulated prods with clip end operated by a butron, and this can then be attached to any required puinl, OJ tU ) '1 00 the binary cuded cJ~cjn,al divider~ OT other !Cs.

A check of the pulser should s'how • range of rate•, adj111table in frequency to suit the purpose, and according to the posltlon of SJ. Current drain ls small, typically 2mA to 3mA QC so.

Componenrs for Variable 555 l'ulser (!Jirure 47/ (~sturs 5% l&W)

RI •1.7k R2 2.1k 10 lBOolun VR 1 SOOk linear

Cl C2

potentiometer 33 µt' 1 µF

! ·ARMED BANDIT

C3 C4 SI

25nf JOOpF siogle-pole 4-way switch

SSS and 8-pin l)!L holder l(nnb1, ca.1e. boacd, et.c.

This i\ u mnre amhitiou:s ga1ne project, hut can provide a grcal deal of an1usemet1t. When the Rl:N sWlteh is pressed, three numbers ehanRe at different cate1, tho9' •rising at random mnatmng dlsplayed when the switch ls released. To impro"e chances for the player, individuQJ HOU>S are fitted, so Iha!

89

• ' I "'

.., (I: a:

>- 0 0

f.j !i ,_ ..

0: "' Q. ... "' 2 ~ .::> i z

1 "' "" . ... .., ~

0 IL _, 0 :r " 0

t "' ....

+ ... "' "' ...

0 :i:

cl ;> z G( r :! d u

"' "' "' ,_

"' u "'

a: .,

" 1 "' «

a: "' di "' ID .tx:

01 .., 0

,_ GJ" ..J "' .,

0 :r "'

u "' t

-90

'

wanted numbef3 can be ret•ine<l while playing for others to sult.

F>gurc 48 shows the cin:uit. RI and Cl control the p1~sing speed of the UH Tt I. Ha:<e I of 1 rl dn•t.f T r2, which in tum op<rates the numerator from ib collector circuit. Tri. Tr2, with 11s auocfaced items and the switch HO LD I, with 0-9 n1.11ne r-Jtor, form one numeral.

The HOLD switch is nonnnlly closed, and PLAY switch is M rmally open. When Che PLAY switch is cfoseJ, Tr I dom1hences to produce pulses wl11ch or•rate thi$ numerdl, which contlnues to change so Jons as the PLAY switch is closed. \\1ien the Pu\ Y <witch is opened I.he pubes ceuc, and the numerator colltinues to dis~lay the figure.

The second fizure is ohtained in the ume """l' ·and h.s 110 LU 2 •wilcli, while the U~rd r-.;urc also opera le$ in this manner, with HOLD 3' •witch . Should any of the !>l~tches HOLD I, HOLD 2 or HOLD 3 be kerr open, then no volta~• reach•• the pul•er section, wheri lhe PLAY •witch js closed, so the related numeral remains unchanged.

Different values arc used for CI and RJ , so that the numher$ run st different rate~.

The HOLD switches should be pusJ1·tO·break, 01 spring· lulid<d toggle types which •re Mnn•lly cli>sed. The PL.\ Y switch Is also of thi• type, but num1ally open.

All pulser and numerator neg>tives are common to the negauve hnc. HOLD switches may $Witch RI, or RI . R2 and RS tOljcthcr, withoot chl!llging rhc count. Numerals can be Nixi< ur LCD, with the diviJ ers, decoders and circuits shown earliec.

In the component !isl, RI •n<l CI arc Si~cn separately.

Comp11ne111s for 1-Attned Bandit. (l'igure 411) (Re•ist(m 5% ~W) 3 ... rr:

R b 47k C!a 0.1 µF R2 ~20 olun Rlb47k C!b 0.22 µ .I' R3 6~0 ohm Ric 220k Clc0.47 µF R4 lk

Pl.A Y 'witch Roa rd c ....

RS l k Tr l UT46, TIS43, £5567 Trl 2N3704 HOU> ~witches 0-9 Numerators.

91

,., "' "' .,, '" "' "' "' "' '" 11.t:i

"' .!:U l:ll

'" "' "' "' "' ••• ... .,, ... . ., .,u ""' .... ""' ""' .... ... ""'' w;J ..... ..... ''"' ... ,. ... -.... .... ,,., ...... ....... .... .... .... .... ••oo .... .... .,.., .... .. M ·­'"' .. ,. .... . .., lc/61 .... .... .... -.... ... , ll'U -· .. ,. ""''' '"'" "''>·' ,,, .... .... .... ""' .... ... , --· -· .... .... •'•J 01'11~

O•'ilt 111"11'1 ......

c;t.& (!"(I,.. •'(-4;Q0"<11tllt110fl Altt1 .... I ~-~-:!II Ciorrc.lu •C'•: l ...... .:i.._.L ... Lo.tiloo~t> , ... t 1«4'0li'iof'i~ I! o.;llt ... 1t1 Jnc-.;.cMililrf'OOOC~~...-.. ~~_,~_....,..

·-"""""'"'&:o.i.C>............_"--...... -·~ ~c-•-~ _._.........._~

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,.

BIRNARI BABANI IP84

IT u a~&1't the ne11vcomer to the hobl.Jy, tne autlior included a number of board layoutli 11nd \Viring diagrams Als.o the more Oln1b11ious projects ha Jo b('en des19ne<:1 to he built a11rt teste-t.1 section by se-ct1on so as to he-Ir!: 3\<0td Of eaMIY curre<,;t any faults that miyht Ut;~ur.

. .

•