oIhoi Auxxpeicpunuuxhoxd

xezpOilpxoleinpouahiqd mot xoguotu

xoj snqresxaATun

986lAIDA

, frt. LINEAR I C. CPU RAMS CRYSTALS INTERFACES :CS14

745743174,70337401745703674077803736741074n741274)374147416741774207421742274574575574277428745743274337437742874397410714774,2A74K14.74447445744047417474467450745174537r,s74607470747274737474747574757483748174334748147557486748674914745174MA7ens.7494745474967437747007410774109741107411174116741167411974120741217412274123741257412674128741327413674141741427414374141741-57414774148741507415147415374154741557415574157741597419374151741627416374164741657415,741677417374172741737417474175741767417674179741807418174162741647417-4741307419174142741437415174156741967419774196741567422174251712457425574773742757477574279742837425574507429374256743517437-47437-474357A749960743757439)

0_331300336300360.330.400.400300.330 3)

0370.500.700.368400.3)0 900360360.400.400.320.430300.360.330330.400.400 630 930.701 031.101.031_031.031000360.3600_3333

003355

0450.460_500.600_46101

1101251.100.422_100360.700.700561.10

00690

2101330500_150.750_551701.101.701_030550.700800.560550550.75

0900.70

2.2.9)70

2.701.101.701601.750.700.931.40

0.93193

0.601.751.100901.101.101.201.13

404 0310342)1.401.101051.031.50150LCO1401.101.101.501_301.331.101.151.100.501331.702202_571.101.101.500.832.031.401.70aso1 as3200_900901.932_030.500.800_830.701.931.10

7433371.44274393Tux,

1231.101201.40

7445 SERTE 5

741533 02474501 0.24741502 024744.503 0.2474501 0.24741506 0.2474503 0.2476509 0.24741510 0.2474511 0.24741512 124741.513 0.3474514 05074515 0.24744.520 024741521 0_24741532 0.24741524 0.50741526 024741527 0.24741.528 0.2474530 0.2476532 0.24741.622 024741537 0.2474533 11.24741543 0.24741.91.2 0.507415477415-2 0.90741551 0.24741554 024741556 0.2474573A 03)745744 0.36741575 0.6745764 036741578 0.4274LS834 0.70741.585 0.75741566 0.35744533 0.45741591 033741592 0.35741593 0.54741566 0.7574595 0.317416107 0.407415103 0.4074/5112 0.457415113 0.45745114 0.457415112 0.70745123 OM765124,629

1.745125 0.50407415126 0507415132 0_65745133 0.50745136 0.4574L5139 0 557415139 055795145 0 557415147 7757415149 1.407445151 0.65745152 2.007415153 0-657415151 1 6374/5156 065741.5156 0007115157 0367415159 066744.51607. 0.57415I614 0.757415162A 075741.51514 67576.516.1 0-57451654 13374151664 1507415163 IW741.5169 1007415170 1.4074151734 1 CO745174 0_75745175 0 757415181 2007415183 1.907415190 0 757415191 0.5741.513 0 807415193 0.5074151944 0 7574151554 0-5.4.51% 08345197 0-83

-4_5221 100 -5240 0-50

-4L5241 097 15242 030-:.5243 090

4_5244 05)"4_5246 103.4. 5247711.5248765249745251745253745256

1 101 101.10050750 90

74/52574 0.707415.2934 0 70741.5259 120745260 0 767445261 120745266 0.607415273 1 257415179 0.70741.5290 190711583 090745290 080765292 9_037452133 OW741.5295 1.407415257 957415296 1.637415299 2.207415731 170765324,624

350745346 2.077415352 1207415353 1.20745356 2.107415363 1337415364 1 ED741536 0507415366 0507115267 05274L53193 0507415373 OM745374 0107115375 0.757415377 1.10

7415375741537974153817475393749393745355A744.5199741541574154667415467741551,07445541741567741551374156127415M47415156741556741565741561074156401745117415E57415612-t7415643741513 17415644741564574155451741566974156874567374156627415547415687745227452374U-4574C516

45040)140..V.93:6A-1074733Acraa

40114012.40131014515401640174018031;4054571.7224013zo24sanAna457

4050330.vaar40324033,tau4035435413741380339404)4041034240134314

,1540464)470)4840494514510E2475305405345645940604054.1664578.1etce74:re4CW6.7067140724373

43760244775

4377 0151075 0254091 0_244(42 075438; 0.63456 0.75X:ES/ 120

3 350454435 0934795 0.904337 2.704033 0.75419 0.904071 0.364532 0.554533 0.364514 0.95

3.604506 0_504537,0333 03540345150 0.554511 0.564512 .554513 1

0.50

4514 1.10.615 1.104516 0564517 2274618 0.611519 0324=1 0.60621 1.1545-M 0904526 0.704527 090478 0.66661 1.034531 0.5

0.951.40ISO0.811.101.031.401.931201.501.001.007.03

19.W19.03150

2_251.401033602.002501002.933 003502.034.000900_931102_503503_93650650657650

0240250.700250.000450600.240750.360 600.7003600.600.500.100600.700.3)0.450140.900.400.930.750361251.031252_500.702.501.101.072500.600.550500600901.000.10aso0550360.350.650.5006.930

00.W0E64.000.700150.402.93

0240_25

0250240240.24024024

453215344064535453945414504551456'345545564557459)45664588594572459345E44915472414411/4412144167441914493141951455T459622100510)22151C01443350157

03.793510)

43101401015103401014015141030310740108510340110511451474015340173011744015401M83,93031914544524543E753373537414"4-4A

MC97

0.65ISO2.500.750.750.930.701.102_400360.502.401.401.402.401.700.450.900.48

1309.0075030)2.E04234_506502.033507.007.000481_200360.401.501 251502001201.500480553201202_25252 931.001 201031_001 OD1031 001 5015.71601 971.600.7505G

Full rangeof 74S Er74H Cseries instock.Ask forfull list.

Irr=3:11700

Wm"

7.07591 1200AEICCEEB 11.934-74791001. 5.00474103 200AY/ 5050 1.03AY3 Irs0 3.504139010 4.937.43 6910 400AY3-512 5.0CA331.94 1.00CA_SA 1.10CA3005 0.711C.456e3 320CA3050 350C1074116 0.70CA3336 0600CAXME 210CA0411413 3.75CA3155 0.90CA31307 1.30CA3155 0.6CA315T TO)CA3116 25CA31635. 090CA31610 200CA3I6-7E 603GA31695 270CA32405 150CAr40141 2.7007002 6.03174C1033 8 300DACOSCO 3.0313407333,

HA135547106IC176111CL750517E6)1CL933510521510.1721710031451C1.17556LC71213107133LC7431107137L534717351L73531E355175671LF3574.411CCLH1.1433141../.133711.14714" 14I.1.431017.531111.131813.1319Llt32417.1334311.1335Luna1.0.tnamass

57ve.m ar,L17LAMA 811.1354101,739)474

:-*.7i_vtn710338314133117.1392741.7.7333onstorLvrire

3.001.935.758964 002-9)4.03

22 CO7.500901.403003423.50

120350

0600.930900.951004.500350.450.752 250.60191.800.151.151301.830 40

0.503.031.931-931.702-003252-20

2701.03

1.801101.100.654.000350 46

VOLTAGE REGULATORS15 FIXED VOLTAGE PLASTIC 10220

516V

12 V15 V15 V24 V

79307EC677872

781579197324

0.460515000.460-50050033

-1/6156790673)379127515791870,4

0_500500500500,500500.50

1A FIXED VOLTAGE PLASTIC 1092

5 V 78405 0.306 V 79106 0.33S V 734.03 OM

12 V 754.12 0.33

15 V 79.15 0.335 V 79116 0 45

12 V 79112 05015 v 171I5 0.93

OTHER SWITCHINGREGULATORS REGULATORS

1543064.77.13231:7SHCIES:C5 A 5 v7E1.412

1.40 IC17560350 5.24

14493590 714-376.40 75409.00 004155

2503423.003.512_93130

Irk VARIABLE REGULATORS14

11.131341.93175.11.1337T11.13501LUXES(

250150

2252 40

4.0015.00

L 5172311 0.507ER GKC 7.037sGutc 21579HGKC 6.7579GU1C 25079MG12C 1.40

OPTO ISOLATORS

1L0747.57251,55.240)MOC350TIL111

1.302231.071901500.70

011121111137111161941376.039

DISPLAYS7..0457 1.00 147.7,45104t4M) 71123)1.03 11585E817T10507,111725 too null7.17.4474 01704 1.00 TurnMA/171 DL707 1.03 TIC0.1.4143540 1.75 MA148310M474160 200

DISPLAY DRIVERS9363937017591411.915LAMMuorasua

UI-112003U1)14516.1

2157771377W919W21

71

4_504.501503_503.50121

050

ULf5C01UL712063041142932U17:2303UL.4501.515175:32

OTHERS0_50180222

091,12ORP6)04761

0_700_700.703601.5

2005.706.501.0)1.00150

0.901.501.93110

0 70.901

0.70

1101.201_20

rrEcitNom.vri(: 1A-1)

1.01711LA1751.1.1725041.74733114174111.174717.1741LA110117.7.710)4L mranLAMM1.1.119111/.11872LAIIREE0.1193317.01917045021.413803L A5976uront)15133141443315L153160.11500

45151347.1515157,1637120301310451413MC145371C14854.MC14951.5330)03034017.1M4330710074All:93240411,53333

1.030 603.W0 650220.700304601.503 CO2501033_006424.573000931-031.001.803.503,403401_50

2304502031.500.750.453000.702000.700.004.00900790

14520 50314522 4.001.114662217. 300

185531NEM146456tacosrams7:055745577:5578E571

1855532P

1/E.:3-1711a534AP

07830771102.4RC:135504151RCSMRC1558

1200220 804.001201_571.25403.00_93IR)1.60133150

5.005.000552_CO1500-00

5568 7.20S9025 90054419)) 16.03SF79654 80051497 3.0

5705033.74 1035777542 4_03575764% 4005976663 120590257.11.2 7 00

TA 71a/14.13074732417.720514172147310

1201.401.570.931.90151

184.51734507184810raastaTBA8201.784320

1

13453TWIG!)TGA.210TCA220TC4.510

70410107350703707.102410411705TDA2032704203311082901704.2051042021105033311134259)11345107DA70.0754105

roxicvT1.1132TL054

TL07T1071

211.07411.51TLC621563TL/731T109471170TL5DC

114.711003 9

L/42240U4.4123011. 14UL75013344.11.7005441.7Q0511.7170232ULTZ51133Lt11779.14

14UPC59034UPC115911.7PC1 TEN

5510XR5395n2n7XR.n115.5216562240

218101211414214419P57,4236214421554-55ZN-S2SES21442758nams214429-371141755441,97115455274459C 1.zrrinAtEVi104027841333.7.14&23-4E&MC)

1200.800.900900.152.032,35502503501.75

264501.103.033251.902_40320

2504 00 03507.00

0 030 CO093u eo0701.100.5OSS0_75142200050120

33.231.201.705500.750.752931501.931932752033035.00

4.424603 755.75

120675

0831.751 30

3501_30

3 00603450225

1C0950

7.503.07200660

23_5950

1203

*ATTENTION*ALL PRICES ARE

SUBJECT TO CHANGEWITHOUT NOTICE

SCRS LOW PRORIE OR SOCKIRS BY TEXAS

II pr. lop 70 on 18p 23 -t5o, llp 22 on 72p 4;_ -

Tana56.5502MCO2502465023

6832539555583956556507.15835935935A93354axt8741874187-ZT4151631141.5395071599E6INDS260ZECIA2906

6_5010.50

12-00250

5_5013 002.503 0/6-93

120012 CO16.003613

3 5134204203.42

22_101750165180012.031450120014 502833257_03

UPPORT DEVICES

203132E23245

9372

5724653256,7.(51saa21

664)53-4365506E85056255466E545551548156815362351126216!M4ans

12038_CO4_503_033932.53550493

1_93220

12_503.756_031102_502-506.508-035008533833.93

2_201 67

POA_425

8243 2.608250 950/31514 32582531.5 3506254C5 357ana 18 CO625705 4_1084590 5 4036275 5.5M75.5 4909)83 400ezEn 450nal 4.608637 4-256e9613 11938T*.."4,7 1 2 97415451/77,16.50111.159332Tm.5195317.1551111.1$9974577107477.010

'A 749E.A.V.05 SOp

8031/ 140p1E2:100.:20920060 45p57cR10. 35E0TIC4.4 36p21115.25 130p24-44444 140p295C60 439

ZENERS2 75 33.403414 5-18.

MACSPints34 4301 6060.5 IOW 70p64507V SOPEA 4004 75pSA 5001' 95p1746=8105pMASON 131:6

29020 130p117050 509111724512

DISCRETEDISPLAYS

LEDSF.REDGREEN111209 0.12

110211 0.16Y513_171411L21Rec

2t

LEDs033

16/G rY1 0.33C.X13 101Wm. 160ID LEDtrot,

7_25Coven 2_75

111220 0.15711.222 0.1511226 033711.32 056111.76 0.55111318 13311191 120

16 4014.035 OD5.0500842145250275250

,,ACTC 2.523;0461 6.50.E3AD7.RT 60370140514 7.5025450 7.07

honed PanLow Profde

Sockets

51.10.7 a9 Cl W.68017-C8014181.1678C17788C179801821180784:1802125113013,18C214/18077803581.477881;516713913C547/813C543G

109lEp20940p40p30p30p15p2Dp

16o16916936p50p20p160

5145.4

BCY71

BD131BCY72

1313132BCHE813136131)15802118BD242385445131-zo.B8E2518

2?

18p11141

369249

30p754150p40040940pTop75pOIP50p409

87E7 36o87F493 ST 32p

2)161550 4002101 4032112 25721074 5.032111435 4072114-3 2502147 3200327.3 3.004116-15 450411620 154118-3 5.0041756 29 15.034164-15 ID 5.54164-15 45416120 320,41615 5.03452-20 253481641,3 2005101. 501 3706514:5114 450515 55061113P 3 493611640-3 5934351.75 10.0051 1.6074510 5 225745,271 34771525 2_593415 6 CO931.45 9.50934.5 60)

ROMS PROMS

:a:2224517185.77)53:60.33

740157855771025745E7

M5M573173M5123

4032_532.032.001.602.51.832.51.501_501.75

EPRO MS

516 - 5v2516 352555325256.17752716-5V2716-35273227P -A21732A 312732,17764.5270.129Z715-5271233)2756252756-3)1415715

3505504_505508.004.033.505_534.507_00603542450

1300953950

36.0034.035.00

CRTCONTROLLER

0475347 16.03CRT6515 9.5679363 8.306535. 25.005E9365 25.56.4-1R,/ 36.60MOW.- 6.501.105155P 6501.1.5647 6 50SFF543:4 8.574159318 15.001waa27 7.5011.1.53925 10.421-7.10975 10 00

37-75 kHz 1001 5 1.114, 27015432 MHz 225703 7.7N, 225255783.710 31

2_07511-0 2.50

2 662 MHz 2503_12 Mitt 1.753 275 400 1.503 575 PalTe LEO4 CO MHz 1.404-197 611, 1.50

43 404, 1.004.638 MHz 2504 9152 14144 2.00550 7.1m., 1505093 1.756 07 4110 1.405_114 7.1.114 1.40/CO 14147 1.507 163 D.W. 1.75803 MHz 1.50557 MHz 1.2510 00 74144 1.757050 MHz 25010 70 1.1142 19311 01 140.4 30712.00 7.153z 15014 CO MR, 1.7514315 NoN 1.6014 756501.4 2507555 M114 2.0016005410 2.517 734 74Hz 20018110 MR: 1.70135 PAH, 1 7018 71147 15019593 MN, 7.50550 7.1144 1.7524 CCO MK: 1921:303 MHz 1.751167.1R, 2507501073 12.1.0

DISCCONTROLLERS

-13K.7270177170151413175F01794401E71,513275WE12797V.E17691

89316.0020 0370.0720 0781022 00M CO32.0315 00

CHARACTERGENERATORS

R0351313,72.50

01) 3 513LC7.03

REAL TIMECLOCK

7,569157- 4.5M2,6917441485

%5353BAUDRATE

GENERATOR7.50

CC151/6 6508 7.50

KEYBOARDENCODER

8IE3Z376 1150415-953 7.50740922 540740923 6.50

UHF1.1000

49561) 21/C0407551 1210ADC7C6 12404.7.125513 1504,11.525213s34 4291525 383r5oAM242.531 123A1.126LS32 120

4,179155 25.0)7CM 6.1:04180 C81 v.

25.0046131 6.00FM03 250WWI 5.0355330 1.4093931 ISO58322 1.51358533 21559326 193S8613 215C1.3 0.60

4E4 0.60/.1C11:34.46 2.507.103457 4507.113.170 415503480 8507.103436 25745P17 225MC4,54 55C1.50341 SSC,4514411 9 CC1514412 151411,2033 0.55107 09075186 oat75109 136'5110 0_9075112 160nua rn35114 14075115 1.4075121 1.4075172 1437515P 1277516: 12375159 21075160 smThus; 3507ste 4.0075172 15751M 0507515 06073.142 05075365 1515451 05075452 0_507545 0.7075151 0.705667 15075491 0.65754M 01513726 158128 123555. 1208193 1 5

16556197

120120

51155 1.4081155 2.581157 TAO81155 7_5814.6123 503532 3.55564 1 5963747 1 -EC9038 200

TELETEXTDECODER

54455 6000.44535

4.45041 160004455, 9.00

6 MHz 3.758 MHz 450$00110125)01412 1.04 1200

UARTAY 3-10157 35

5-1013P 103

001.3)17300

.-.2 4 50

7643,30

185017

WISE Velt&P SOCXE VS OT TEXAS

844n14 p.16

30942p45p

180n2011n22 on

SO0 2474"800 28 P.,650 404>r

70:.7.:c

1 T

13935p

TRANSISTORS

20 on217..

40175547

913.9)474637.115011.1_5554143301ALIM36515E10553.3991W.At771037,4747/51.479412111,251E171P3T1P31C11P32CTIPECT,WC

330909

2259900

2259150p15p40940040p50040p

1409

40p

45p

110361.711141C10427.11242CT1P471175411FT1P125117311733%21G1t50.9.2215A2737124nacara06anum.:270053non.

150p

5139(Sp

1163p1609

73010070,1

350.

39p

IOC CONNECTORS ENOOES

P.; 909 1459 1759

ITSX 1504

Cess 1267 1959 2409

200c. 220,

1600 190P

3209 3409

61/710 CONNECTORS

115,2811501.0 2 5.14,ang'ed 3 - 32 realMr 2 32 wsi 1..,fr a 0094 ,DIll 41617 210111 41617 31-044DIN 416122 32 lera,1 ST Re2 3211'31 Afsg Pal3 32 pay 51 Pin3 323.37803Pn117 511 A -

C2, 2 32 real On..A - 0. A Ci

MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NW10 1EDSHOPS AT: 17 BURNLEY ROAD, LONDON NW10

(Tel: 01 208 1177 Telex: 922800)305 EDGWARE ROAD, LONDON W2

Im=1

7359

2004,

330.

5Cp 3609507 444004000 -156 5501709

moo nsnvsp. nop2609 500V5p, 40,004254142544

9712704470 490049'-2495

22 on

yC

, ,

:35

129 06100 Qr10p 0:202 10P9, 16474 4-9p IN1143

: -

monk;

ExcCr.

IC,4.Tc

r5c

7AWV 1991070C. 2761160C.2350. 3:1,7415. lip

63p559

1009809

9.4X. 120p641009 1500104.1Wd Imo1034007 207P

MN 0 CONNECTORS

AA,AL

. Ai. "S AA :5 ag.VILS

.k 536. 130I1., I05 77.E

sco 734, 176sk 275 2541

532 e -en, 509 710

37 ...T. 29e c.:rnVC SwanWm 116o Soots 4601

939 I COo559 7.51 455099.,..7

PLEASE AM) 54Ip p&p & 151.111.11.(Export no VAT. p&p at Cost)

Orders from Government Depts.& Colleges etc welcome

Detailed Price List on requestStock items arc normally by return of post

Elektor Publishers Ltd., Elektor House,10 Longport, Canterbury CT1 1PE,Kent, U.K.Tel.: Canterbury (0227) 454439.Telex: 965504.Office hours: 8.30 - 12.30 and 13.30 - 16.30.

Editor: P.V. Holmes

Assistant editor: E.J.A. KrempelsauerUK editorial staff:L. Seymour

Overseas editorial staff:P.H.M. Bagger), A. Dahmen, I. Gombos,P.E.L. Kersemakers, R.P. Krings,P. v.d. Linden, D.R.S. Meyer,G.C.P. Raedersdorf, J.F. van Rooij.G.O.H. Scheil,

Editorial secretariat:C.H. Smeets, G.W.P. WijnenHead of design:K.S.M. Wakw:en

Laboratory staff:J. Barendrecht, G.H.K. Dam, K. Diedrich,G.H. Nachbar, A. Nachtmann,R.A.F.M. Salden, A.P.A. Sevriens,J.P.M. Steeman, P.I.A. TheunissenPublishing manager:A.J. BrialeyAdvertising manager:S. Brooks

The circuits are for domestic use only. Thesubmission of designs or articles to Elektorimplies permission to the publishers to alterand translate the text and design, and touse the contents in other Elektor publi-cations and activities. The publishers cannotguarantee to return any material submittedto them. All drawings, photographs, printedcircuit boards and articles published inElektor are copyright and may not bereproduced or transmitted in any form or byany means, including photocopying andrecording, in whole or in part without priorwritten permission of the publishers. Suchwritten permission must also be obtainedbefore any part of these publications isstored in a retrieval system of any nature.

Patent protection may exist in respect of cir-cuits, devices, components etc. described inthis magazine. The publishers do not acceptresponsibility for failing to identify suchpatent or other protection.

Elektor is also published in Dutch, French,German, Greek, Italian, Portuguese,Spanish, Turkish and (in part) Swedish inassociation with AlIt om Elektronik.

Distribution in U.K.:Seymour Press Ltd., 334 Brixton Road,London SW9 7AG.

Copyright 1985 Elektor Publishers Ltd..Canterbury.

Printed in the Netherlands. jABC;

Volume 11 - Number 5 ISSN 0308-308X

news, views, people

selektorShinina a light on new technology

A/D and D/A conversion 5-22A fresh look at the state of the art.

programmable timer 5-26A truly versatile timericalendar with a host of facilities.

universal I/O bus 5-35Primarily intended for the Commodore 64, this bus can also be used with manyother computers.

an IBM compatible microIn this short introduction, we explain the intent of the project which will bepublished next month.

5-16

5-40

missing link

how to make your own PCBs

glow plug modulatorA means of making your model (diesel) engine start first time - every time!

digitizer 5-48This unit provides the staple diet for your computer from all sorts of (analogue)inputs.

programmable array logic 5-52This modern technology deser:es to be better known to all electronics designers

automonitor 5-60With petrol now past the £2 per gallon barrier, this unit may help you keep your run-ning costs down.

panorama mixer 5-67A four -channel mixer that enables you to position a sound anywhere in the audiospectrum.

5-20

5-41

5-42

5-45

market 5-68

switchboard 5-73

appointments 5-75

readers' services 5-80

index of advertisers 5-82

A selection from our June issue: digital oscillators an IBM compatible micro infra -red detector RAM as EPROM autoservice timer tone burst generator

IBM's sudden decision to pull out of thehome computer market makes a (relatively)low cost PC2 compatible micro even moreattractive. We show you how to build onenext month. This month's cover showssome of the boards used in the project:from left to right - the megaboard, thesuper XTPC board, the video board (withmonochrome graphics), and the floppycontroller board. Inset is the IBM PC2.

5-03

elektor may 1985 advertisement

A new addition to our series of software cassettes for theTV games computer has just become available. Like itsthree precedessors, the present one, number 011, offers fif-teen games for the whole family. Snakes and ladders - reach square 100 before your

opponent(s). Molebasher - catch as many moles as you can. Snap - try to beat your opponent in deciding whether

two pictures on the screen are identical. Mazes - escape from the maze before your time is up.* Asteroids - try to survive for as long as possible by

avoiding the asteroids. Dragster - complete nine laps in the shortest possible

time. Omega landing - land your spacecraft in a hostile

environment!

The ElektorSoftwareService(see readers' service pages) givesdetails of TV games on cassette andon software on EPROMs.

Break-out - twenty-four variations on 'bursting balloons'contained on cassette 010.

* Tiny Tim - remove enough rocks and you reach thelovely girl!

Horse race/jackpot - two simple games of chance. Newton - catch as many apples as possible.

Horse races - eight variations of show jumping.' Painting - colour the screen without being bitten.* Submarine/racing - two different games: in the first,

the submarine tries to sink as many ships as possible; inthe second, a racing car must avoid other cars on thetrack for as long as possible.Cosmic adventure - a three-part game: first, destroy

twelve meteorites; second, land under enemy fire; third,find the nuclear reactor in the underground maze.

Magazines are valuable! Keep yours in good condition in

THE ELEKTOR

CASSETTE BINDERThis cassette style binder will help to keep your copies ofElektor Electronics clean and in order even though yourefer to them lime and time again. The chamfered cornerof the cassette allows instant recognition of each month'sissue without the need to thumb through pages of pre-vious months' issues. Because no wires or fastenings areused copies can be easily removed and replaced andeach cassette will hold one year's volume of Elektor Elec-tronics.

PR/CE 1'3.10+55p P&P, U.K.

(E1.10 outside U.K.)

available from -Elektor Publishers Limited,

10 Longport,Canterbury,

Kent CT1 1PE.please use the order card

in this issue.

PRODUCTSBBC Microcomputer Model B £299 - VAT £344BBC Mod B - disk interface 1346 + VAT £398BBC Mod B - Econet interface C309 + VAT £355BBC Mod B - disk and Econet interfaces £365 + VAT £420BBC Compatible 100K disk drive E86 + VAT £99BBC Compatible dual 803K disk drive £251 + VAT £288Acorn no E347 + VAT £399Acorn 6502 Second Processor E173 + VAT £199Acorn Bit stick £327 + VAT f31*Acorn IEE Interface £282 -r VAT £325Acorn Electron plus 1 interface £52 + VAT E60BBC Prestel Adaptor £121 + VAT £139BBC Telext receiver laug) E196 + VAT £225BBC r-anne recorder and lead C30 + VAT £35Disk interface kit If fee fitting) E84 + VAT £97Mod A to Mod B upgrade kit £70 + VAT £80fining charge for A to B upgrade kit £20 VAT 12316K memory upgrade kit £30 + VAT £34Games paddles £17 + VAT £19User Guide £15Advanced User guide £12_95Econet Guide E 7.50Econet interface (free fitting) £60 + VAT £69Speech interface (free fitting) £47 + VAT £54BBC disk manual - formating disk £30 + VAT £34Parallel printer cable E10 + VAT £11BBC word processor (view) £52 + VAT E59

YOUR CONTACT AT AKHTERTel: 0279 443521 (12 lines)

DEALER/BULK ENQUIRIES _ HAMAYUN klUGHALTELEPHONE ORDERS - _ CARON ANDREWSDEALER ORDERSEXPORT ENQUIRIES -. - MOHAMAD EDIBTECHNICAL SUPPORT ALAN LAFFOLEYACCOUNTS __ - JULIE AMBLERLITERATURE REQUEST _ JOHN MAULE

ORDERING INFORMATIONWe accept official orders horn UK Government arid Eaucationestablishments Carnage is £250 VAT (11K only) for normaldelivery II express delivery is required please add [BOO 4 VAT perparcel. We accept telephone orders on Barclay and Access cardplease ring (0279) 443521 (10 lines) all cheques mane payable 10'AKHTER INSTRUMENTS'

EXT202210209201207211201

111.

N.B. All prices are subject to change without noticeand are rounded up to the nearest pound

OPENING HOURS: MON-FRI 9am-6.30om. SAT 10am-Som.We welcome callers. no parking problems.

DRIVES100% ACORN COMPATIBLE 51/4- DISC DRIVESMD100A Single Drive 100k 40 Track singe sided . f136 - VAT E99MD10013 Single Drive 100k 40 Track Single Sided - PSU £112 - VAT E129MD200A Single Dine 200k 40 Track Double Sided 012 - VAT E129MD2008 Single Drive 200k 40 Track Double Sided + PSU £138 r VAT £159h113202C Dual Drive 20131) (2. 100k) 40 Track Single Sided f164 + VAT £189M0202D Dual Drive 200k 12, 100k) 40 T SS PSU +Morn. Stand 1216 + VAT £249MD202E Dual Drive 200k 12, 100k1 40 T SS + PSU + MetalCase £216 + VAT 1:239MD -100A Single Drive 4001. 401E0 T smatchable Double Sided E129 + VAT £149MD4008 Singe Drive 400k 40130 T Britt able D/SidedPSU 1155 + VAT E179MnaroC Dual Drive 400k 12, 20Dk1 40 T D/Sided £216 VAT 1249MD4O2D Dual Drive 400k 12, 20011 40 T D/Sided PSU Mon St E269 + VAT E309ME402E Dual Drive 400k 12 .20011 40 T Di Sided PSU 4Met Cs E2E0 VAT E299k1D892C Dual Drive 800k (2, 400k) 40/83 switchabie D/Sided E251 + VAT E299MI3902D Dual Drive 8004 12. 40011 40/83 switchabbe D/Sided

PSU + Monitor Stand E303 + VAT £349MD802E Dual Drive rook 12 a 400k) 40/83 sv/itchable D/Sided- PSU Metal Case £2E6 VAT 1:339

The Akhter Gold StandardDUE to the high standard of the Akhter Disc Drives we have takenthe unique step of introducing -The Gold Standard- a TWO YEARwarranty on each and every one of our drives sold after April 1st1985. To qualify for this 24 month guarantee the lucky puchaser merely returns his individual registration card included in every box toAkhter. Buy your drives with confidence BUY AKHTER!

3M DISKETTES:48 TPI SS DD Diskettes (Box of 10) £1548 TPI DS DD Diskettes (Box of 10) E1896 TPI DS DD Diskettes (Box of 10) £25

BUSINESSSYSTEMS

COMPLETE BUSINESS PACKAGEThis system is based on 16 Bit 8088Processor 128K RAM, 2X730K FloppyDisc Drives, High Res Monitor. fast(160cps) Dot Matrix Printer, WordstarWordprocessor, Calcstar SpreadsheetProgram. complete integratedAccounts package consisting of SalesLedger, Purchase Ledger, NominalLedger, Invoicing, Stock Control.Payroll and mailing' list.Complete turnkey system at anunbelievable price.Delivered Only £1495 + VAT £1719Delivered and Installed plus daytraining £1595 + VAT £1834APRICOT PC'Portable Executive Computer" 16 Bit Micro. 256K RAM up to 1.44 megabytes

flopy disk storage. 31' Sony disks. Portable brief case styling. Modem with autodialler (optional) hard disk optional. Vast software library (compatible with Sirius

Apricot with Double Drive. Monitor and Free Printer £1790 + VAT £2059

APRICOT XIAs above but with 10MB Winchester Drive and Single 315K Drive plusSuperwriter, Supercalc and FREE JUKI 6100 Printer

£2995 + VAT £3444

SANYO PROFESSIONAL COMPUTERSANYO 550 SANYO 55516 Bit Micro 128K RAM expandable to Sanyo MBC555 128K double drive and256K. Single or Double Disk drive built free software including Wordstar.in full colour graphics (640 x 200 pixels Calcstar. Inforstar. Detester etc,in 8 colours) IBM compatible. Free £999 + VAT £1149software. Sanyo MBC 550 128K RAMsingle drive and free software includingWordstar and Calcstar

£749 + VAT £862SANYO 550-2As 550 but with Dual Drive 2 x 160K

£849 + VAT £976SANYO 550.360As 550 but with 2 x 360K Drives

IV99 + VAT £1149

SANYO 555-360As 555 but with 2x 360K Drives

£1249 + VAT £1436

SANYO 555-730As 555 but with 2 x 730K Drives

£1299 + VAT £1494

SANYO SYSTEMS INCLUDESANYO 550-730 FREE HIGH RES GREENAs 550 but with 2 x 730K Drives MONITOR

£1049 + VAT £1206

WORD PROCESSINGCOMPLETE SYSTEMS FROM £650 + VAT

BBC 1: BBC Micro Model B. View (orWordwise) Wordprocessor, Ouendata20 CPS Daisywheel Printer, High ResGreen Monitor, Cassette Recorder plus10 cassettes and all the necessarycables £650 + VAT = £747.50

BBC 2 BBC Micro Model B + DiskInterface, View (or Wordwise)Wordprocessor, 100K Disk Drive. HighRes Green Monitor. Ouendata 20 CPSDaisywheel Printer, 1 Box of Disks andall the necessary cables

£799 + VAT= £918.85

BBC 3: Same as System BBC2 but with400K Drive

£875 + VAT = £1006.25

BBC 4:Same as System BBC 2 but with400K Drive and JUKI 6100 DaisywheelPrinter

£975 + VAT= £1121.25.BBC 5: BBC Model B + Disk Interface.View (or Wordwise) Wordprocessor,800K Dual Disk Drive (Mitsubishi), HighRes Green Monitor, JUKI 6100Daisywheel Pnnter, 1 Box (10) of 80Track DS discs and all necessarycables £1145 + VAT = £1316.75.

SAN 1: Sanyo MBC 550 Series 16 BitMicrocomputer, 128K Ram, Dual 160Kdrives (2 x 160K), High Res Graphics(600 x 200 pixels in 8 colours), JUKI6100 Daisywheel Printer, High ResGreen Monitor. 1 Box of 10 discs,Wordstar Wordprocessor, Calcstarspreadsheet and all the necessarycables £1175 4 VAT = £1351.25SAN Same as SAN 1 but with Dual360K Drives (2 x 360K)

£1345 + VAT = £1546_75SAN 3: Same as SAN 1 but with Dual720K Drives

£1395 + VAT= £1604.25SAN 4: Sanyo MBC 555 Series 16 BitMicrocomputer. 128K Ram, Dual 160KDrives (2 x 160K), High Res Graphics(600 x 200 pixels in 8 colours) JUKI 6100Daisywheel Printer, High Res GreenMonitor. 1 Box of 10 discs, Wordstar,Wordprocessor, Calcstar spreadsheet,Mailmerge. Spellstar (dictionary).Datastar (database), Reportstar plus allthe necessary cables

£1295 + VAT = £1489.25.SAN 5: Same as SAN 4 but with Dual360K Drives

£1475 + VAT = £1696.25SAN 6: Same as SAN 4 but withDual 730K Drives

£1525 + VAT =£1753.75If you require High Res Colour Monitor instead of High ResGreen Monitor in Sanyo Systems please add £320 +VAT= £368 to the above prices.

128K RAM Upgrade for all above Sanyo systems(makes a total of 256K RAM) £150 + VAT

=£172.50 Including filling.

-........ .-........... ..... . -

elektor may 1985

New electronics enclave?Electronics firms now provide ninetyper cent of new jobs created in theWest Country, says Devon and Corn-wall Development Bureau in abrochure reviewing the industry'sprogress.Six thousand people in the twocounties now work at electronicscompanies, which cover a spectrumfrom virtual one-man enterprises togiants like Toshiba, TexasInstruments, British Aerospace, andPlessey. It is expected that much ofthe industry's future growth will bein design and development.The drive to bring jobs to the area isto be spearheaded by the bureauwith a centralized office in Plymouthand an overseas office to beestablished in Boston, Mass. Govern-ment assistance to the bureau islikely to rise.

The chips are down...According to National Semiconduc-tor, one of the world's major semi-conductor manufacturers, the mostimportant issue affecting the elec-tronics industry today is theunprecedented decline in semicon-ductor sales during the past months.At no time during previous re-cessions have the industry's orderbooks sunk to such alarming levels.Although the personal computerindustry has been the prime cause ofthe peaks and troughs of the presentslump, the whole OEM industry over-estimated its need for parts. Sincethe European PC market is small incomparison to the US and SoutheastAsian PC markets, order books inEurope have not experienced thesame tremendous drop.The most affected product lines arethose for memory and logic circuits.Telecommunications is the strongestarea now and new products such asthe dedicated telecom devices, theSeries 32000 family, and gate arrayshave not been affected as seriously.It is expected that the decline willslow down when semiconductorbuyers have corrected their stocks,which will probably begin to showduring the coming summer. Nonethe less, semiconductor sales will notfully recover for some time, andNational Semiconductor thereforeforecasts very aggressive lead timesand pricing during the foreseeablefuture.

Tractors by satelliteThe first small -dish transatlanticbusiness satellite link exclusively formultinational companies, provided byBritish Telecom International (BTI),has enabled the giant Massey -Ferguson Group to establish itsworld-wide communications centre inthe United Kingdom.The key to the operation is BTI's

SatStream North America small -dishsatellite service using an Intelsat Vsatellite for high-speed computertraffic between Britain and NorthAmerica.Control of data processing ofMassey -Ferguson operations acrossthe world are now carried out at thefirm's Birmingham centre which hasBritish Telecom MegaStream conned-tions to its subsidiary Perkins dieselengine plant at Peterborough.The two centres are linked through aSatStream North America servicethat allows dealers throughoutCanada and the United States toplace computerized orders via theirown terminals for parts andmachinery direct to the British fac-tories.From Birmingham, high -capacitydigital links carry signals to and fromBTI's SatStream North America earthterminal at Ealing, West London.They are then transmitted via anIntelsat V satellite over the Atlanticto Teleglobe Canada's Globesatsmall -dish terminal in Toronto fordistribution through Massey-Ferguson's own gateway to centresthroughout Canada and the UnitedStates.SatStream operates at 64 Kbits/s.

Morgan would have likedthisCable 8- Wireless has agreed withthe government of St Kitts -Nevis toset up a company to own andoperate the islands' national andinternational telecommunicationssystem. The company will com-pletely modernize the network andwill install a digital telephone

VE

DE: LE

exchange with an initial capacity of5000 lines.The new company, eighty per centowned by Cable 8- Wireless andtwenty per cent by the government,plans to invest f10 million in the firstthree years and will provide servicesunder licence for an initial period oftwenty years.

Operating system of theeightiesThe declining real cost of hardwareand the increasing shortage of skilledsoftware writers have combined tomake software productivity a keyissue today. Software productivityhas two essential components. First,there is the task of developing ef-ficient, error -free programs withteams of programmers working ondifferent areas simultaneously. Sec-ondly, and just as important, there

Unix Shipments: 1984 to 1988

1984 1986 1988

StadarWass PersonalCommatee 1 700 4 000 10 000

SepermAcras 72 000 160 000 240 0008.44roatis 5 000 0000 13 000itainframss 300 700 1 200

TOTAL 79 000 172 700 264 200

row wOCT TYPES Or STSTEMS. TrIC WIMMEITCWEPINCSEOT WI.. OP/TOOTING STSTEr AMOS - MO AaaATO Mtn SuPLIMICOO. IF/. ETC in IOCCASE Or WAIMPOrxES. IT IC OOTIC TTPICAU re& CMIXTO OE ADDEO TO Aft EAISTINC WAIOrnAmE COrPuTCO_

SOURCE: INTERNATIONAL RESOURCE DEVELOPMENT INC.

is the need to be able to transportthe finished program to othersystems to avoid reinventing thewheel. Unix la trade mark of AT&T)meets both these needs.Although it was originally developedfor DEC machines, Unix is nowavailable for many other processorsand each of the major microproces-sor manufacturers is committed toUnix. For a variety of reasons, Unixis now widely regarded as theoperating system of the eighties.First of all, it is a powerful programdevelopment environment. Program-mers love it because it offers a vastlibrary of useful utilities which are allnicely linked together. It supports awide range of programminglanguages - high-level languages aswell as assembly language - and itspowerful text processing facilitiessimplify the tedious but vital task ofdocumentation.Secondly, it is a true multi-user,multi -tasking system. Few softwareprojects today are sufficiently simpleto be tackled by one programmeralone: instead, the program is par-titioned into modules which can bedeveloped in parallel.Thirdly, though many people wouldrate this as the most important fac-tor, it is portable. In theory, at least,the operating system is transparentto the user and source code

5-16Ir

elektor may 1985

developed on one machine shouldcompile on any other equipment run-ning under the same Unix release.Fourthly, there is the snowball effectworking in favour of Unix todaybecause it has already attractedenough vendors and users to make ita de facto standard in the industry,and this in itself serves to attracteven more users. Because they nowperceive it as the standard operatingsystem of the eighties, independentsoftware vendors are producing Unixsoftware and, of course, the abun-dance of independent software willreinforce Unix's position as theleading operating system.Finally, Unix has been in use inuniversities for almost ten years sothousands of graduates have enteredthe computer industry with a back-ground in Unix. Until recently, theydidn't have easy access to it but nowit is being made available on relative-ly inexpensive systems.

Common market forcomputers?Taking a leaf out of the JapaneseMSX book, and, no doubt, worriedby the inexorable progress of IBM, anumber of European manufacturershave at last - almost thirty yearsafter the Treaty of Rome - decidedto combine forces. These manufac-turers, Siemens and Nixdorf of WestGermany, Britain's ICL, Italy'sOlivetti, Philips of the Netherlands,and France's Bull, want to standard-ize on a version of AT&T's Unix fortheir minicomputers.Owning 25 per cent of Olivetti, andhaving a joint venture with Philipsalready, AT&T is wellplaced to pro-mote its standard in opposition toIBM's. As reported in these columnslast month (BT to make microcom-puters), software developed by theUnix system can be used on allmachines on which Unix isimplemented, irrespective ofmanufacture. Might this at last meana real European common market forcomputers? It seems hard to believe.

After a passage to India..A turnkey ATE order worth well over£200 000 has been won by Factron inIndia, where its distributor is PrimatConsultants Limited. The order fromHindustan Aeronautics Limited, HAL,the leading avionics company inIndia, is the first major functionalATE sale by any company in Indiafor around four years.PCIZs ATE programming servicesplayed a substantial part in gettingthe order; the company will be sup-plying a complete package withapplications software. PCL is alsoproviding local training, support, andfield service facilities.The sale is the result of over twoyears' effort, during which time PCL

trained four Indian engineers at itsUK headquarters. The Indian oper-ation now consists of five fully -trained staff at PCIZs New Delhioffice.

Sinclair in the redJust before going to press we learnedthat Sinclair's profits had slumpedfrom £14.3 million in 1983,84 to£7.9 million in the last nine monthsof 1984, owing mainly to writing off£7.5 million on unsold computers. Asinformed forecasts are that profits forthe full 1984185 year will onlyamount to £5 million, this wouldmean losses of close to £1 million amonth from January to March. Thisis bad news, indeed, for Sir Clivewho is now hoping to break into thebusiness market with the QL. But SirClive has gone through tough timesbefore: he survived the richess-to-rags of Sinclair Radionics.It is clear that all computer manufac-turers face hard times ahead, or havealready entered them. Price cuts toboost sales in a declining UK marketare playing havoc with profitforecasts and computations. AlreadyOric, Tycom, Dragon Data, andCamputer have folded, while Acornwas rescued in the nick of time byOlivetti.

The COMFET is here...RCA Solid State and RCA'sPrinceton Laboratories haveannounced the successful manufac-ture of the world's first p -channelconductivity -modulated field-effecttransistor, the COMFET. This devicecomplement to RCA's n -channelCOMFET has a similar switching

speed, forward blocking voltage, andon -resistance characteristics to its n -channel counterpart.Conventional p -channel MOSFETsrequire a larger chip area than n -channel MOSFETs, because themobility of holes (the primary currentcarriers in p -channel devices) is lessthan the mobility of electrons (theprimary current carriers in n -channeldevices), but this is not so in RCA'sCOMFETs. Because the two com-plementary devices have the sameactive areas, they have identicalinput capacitances, which permitstheir use in complementary appli-cations.In general, a COMFET and a powerMOSFET operate in basically thesame manner. However, the on -resistance of a MOSFET increaseswith a rising drain -to -source voltage,which limits its use as a powerswitching element above 200 V. Thislimitation is overcome in theCOMFET by greatly increasing theconductivity of its epitaxial drainregion through the injection ofminority carriers due to the addi-tional p -type or n -type substrate.

Video appealCanada's Chief Justice Brian Dicksonhas announced that the SupremeCourt of Canada is now hearingapplications for leave to appealthrough a nationwide video con-ference service. This service will per-mit the Court to hear applications onits fortnightly applications days fromnine cities across Canada, and somake it more practical for Canadiansto appear before the Supreme Courtof Canada."The substantial reduction in costachieved by video-conferencing andthe convenience it offers litigants andtheir lawyers will improve access tothe Court from all regions of thecountry for the critical leave grantingprocess," said Chief Justice BrianDickson.

Voice of America goesBritishIn a deal worth around $2 million,Marconi Communication SystemsLtd, via their US office, MarconiElectronics Inc, is to supply Voice ofAmerica with a short-wave transmit-ter to be installed at Greenville,North Carolina. This order marks thestart of the re -equipment phase ofthe Voice of America's multi -milliondollar modernization programme.

In the spirit of Hoist?The Performing Right Society, whichhas the difficult task of administeringthe rights of public performancegranted to the creators of musicunder copyright legislation, hasinstalled a Planet remote access net -

5 -17

elektor may 1985

work from Racal-Milgo Limited.The PRS, a non-profit makingassociation of composers, authors,and publishers of musical works, wasestablished in 1914. The main activityfor its 700 staff is to collect anddistribute royalties for its 500 000worldwide members from theircopyright music performed publiclyand broadcast.Currently, the society has seventycomputer terminals connected to theRacal-Milgo network. These accessinformation from an ICL 2966 main-frame computer via tabel topmodems linked with DRS 20/33 con-trollers. Forty to sixty additional ter-minals are expected to be linked tothe network during the next twelvemonths.

Definitely in aapek's!A collaborative research project onrobotics is the second joint ventureinitiated under the recently con-cluded agreement between BritishAerospace and the HatfieldPolytechnic.The particular area of interest is theautomatic assembly of high -precisionmechanical units, and the particularproject subject is to devise and buildclosed -loop controlled sensory end -effectors (mechanical hand) for arobot arm. Closed -loop sensory con-trol means that the robot must becapable of performing its allottedtask "intelligently", i.e., the robotwith its end -effector must be able toadapt to the uncertainties inherent inthis type of work when performed ina factory. For instance, the ability tocope with changes in the relativepositions of the components to beassembled.The industrial impetus for the projectcomes from British AerospaceDynamics Group which intends toincrease the use it makes of robotsin manufacturing operations toreduce costs and improve quality toremain competitive in world markets.At the end of the project, theengineering knowledge gained will beof great industrial and academicvalue, to the mutual benefit of bothorganizations_

I talk, you payA contract worth in the region of£ 20 million has been placed byBritish Telecom with AT&T andPhilips Telecommunications UK Ltdfor a network of nine digitaltelephone exchanges designed toenhance the LinkLine service.LinkLine, due to be launched byBritish Telecom's National Networksthis summer, will help serviceorganizations who obtain a large partof their business from incomingphone calls. It will allow customersto make calls that will be paid for bythe company being called.

British Telecom is continuing toevaluate tenders for the supply ofdigital local telephone exchangesfrom Thorn -Ericsson, NorthernTelecom, and AT&T and Philips, andthe award of the LinkLine contractdoes not in any way affect thatevaluation. These local exchangeswill be in addition to System X,which will remain the major digitalexchange in the UK network.

From Bohemia's fields andgroves...Czechoslovak electronics productionis forecast to grow by ten per cent in1985, a rate which is almost threetimes as high as that of otherbranches of the country's industry.In the 1986-90 period, electronics isto raise labour productivity bytwenty-five per cent, and savetwenty per cent of raw materials,fuels, and energy, as well as 120 000workers. This is important as somebranches of industry, especially ser-vices, have a labour shortage.Czechoslovakia is heavily dependenton western technology and much ofits capital electronics equipment ismade unter licence agreements withwestern governments.

Wee chipsResearch work being carried out atthe Department of Electronics,University of Glasgow, may producecompletely new types of commercialsemiconductor devices and inte-grated circuits for the electronicsindustry over the next few years.A team at the department is workingon ultra -miniaturized devices withline widths that are measurable inatoms. Theoretical research hasshown that at such small scales elec-tron behaviour is altered, and it isbelieved it may be possible to builddevices with completely differentcharacteristics from those now inexistence.The team, whose work is being car-ried out in close cooperation withPlessey and British Telecom, hasalready built a field-effect transistorone -tenth of the size of currentcommercially -manufactured devices,which is very much faster thanexisting FETs and is likely to beusable in the manufacture ofamplifiers for satellite communi-cations.The researchers are now routinelyfabricating structures on three-inchsilicon wafers and gallium -arsenidemembranes that have a line width of10-8 m. Using that size letters, itwould be possible to write the Biblefive times over on the head of a pin.The team uses a technique knownas high -resolution electron beamlithography, in which an electronmicroscope's emitted electron beamis controlled by computer and used

Ei

VIE

PECDLE

to write device patterns on a siliconwafer, gallium arsenide substrate, ormembrane. It is possible to writelines which are only thirty or soatoms of gold in width.

There's gold in them theresands...Frost & Sullivan's comprehensivereport Telecommunications Systemsand Equipment Market in the MiddleEast Arab Countries (#W692) justpublished forecasts an averagegrowth of about two per cent perannum from $4200 million in 1983 to$5000 million in 1990 in constant1982 dollar terms.The lion's share of over $2000 millionper year is accounted for by SaudiArabia, with Algeria averaginganother $400 million per annum, andfive other countries exceeding$100 million.The main growth areas aretelephones (10...11 per cent p.a.);telex services (12 per cent yearly);broadcasting, mobile radio, andrelated equipment (4 per cent, risingto $660 million in 1990); and trans-mission systems, which includemicrowave and other non -broadcastradio systems, submarine cables, andsatellite earth stations (3 per cent -to $2000 million by 1990).Main (almost sole) suppliers to SaudiArabia are Ericsson of Sweden andPhilips of the Netherlands; whileEgypt is served mainly by Siemensof West Germany and Thomson-CSKof France. These two countries wereresponsible for some 65 per cent ofcontracts placed during the period1977/83.

5-18

elektor may 1985

A rotten core?Like Sinclair in the UK, Apple had totemporarily close four of its US fac-tories producing personal computersin March. Its sales are well downand profits are expected to be rockbottom. Apple has three problems:the PC market is on the decline; anumber of its top managers has left;and it still has not managed, in areal sense, -to break into the cor-porate computer market.Among the managers who left earlierthis year was Mr Steve Wozniak, aco-founder of the company, and theman who designed Apple's best-selling computers. He left becausehe disagreed with the company'sproduct -development plans and itsmarketing strategy.Apple's main strength lies in thesmall businesses and domestic com-puter markets, but although Apple Iihas been selling well, the Macintoshhas not (Apple II sales last year: wellover 1 million; Macintosh sameperiod: 275 000). Apple's strategy is,however, to use the Macintosh tobreak into the corporate computermarket, which is IBM's stronghold(seventy-two per cent of America'stop 2000 firms bought IBM last year- only four per cent Apple). So far,it would appear that Apple hasfound IBM's domination of mainframe computer sales and itsimmensely strong marketing networktoo tough a nut to crack.

Did you know...?When Thomas Kurtz, co -inventor(with another mathematician, JohnKemeny) in 1964 of BASIC (Begin-ners All-purpose Symbolic InstructionCode) recently worked on a micro-computer loaded with a BASICprogram, it was almost incomprehen-sible to him. Imitations of imitationsof imitations, ad infinitum, of theoriginal concept produced by com-puter manufacturers (who oftenadded their own 'improvements')over the past twenty years haveresulted in a chaos of incompatiblesoftware so that a program writtenfor an Apple, for instance, cannot berun on a Spectrum and vice versa.But pride of place must go to Com-modore, not one of whose models iscompatible with its predecessor.Kurtz and Kemeny have now decidedto try and do something about thisidiotic situation by writing a book,"Back to BASIC", which is expectedto be published this spring.

Philips' ESPRITAccording to proposed plans, Philips,the Dutch electronics giant, will takepart in seventeen projects within thecontext of the European strategicprogramme for research into infor-

mation technology (ESPRIT). Theamount of subsidy involved forPhilips comes to about 32 millionEuropean currency units (ECUs) orclose to twenty million pounds ster-ling. This amount is based on theassumption that the projects will runfor a total of four to five years. Toavoid the budget being exceeded,the European Commission has com-mitted itself to a subsidy calculatedover the first two to three years, thatis, about £8 million.Eleven of the seventeen projects aremajor ones, and two of the seven-teen are pilot projects. Philips is themain contractor in three of theeleven major projects, in two of thefour smaller ones, and in one pilotproject.The first of the three alpha projects,undertaken with Siemens, covers thedevelopment of methods with whichbipolar and CMOS transistors can beapplied to one chip using compatibleVLSI processing.The second, in which AEGTelefunken, CII Honeywell Bull,CSELT, GEC, and Nixdorf arecooperating, involves research intoadvanced computer architecturecapable of enabling large numbers ofmicroprocessors to work together onone program.The third alpha project, involvingcooperation with CGE, ATT, Philips(Belgium), a number of softwarehouses, a West German university,and the Centre for Mathematics andInformation Technology in Amster-dam, is aimed at achieving animprovement in efficiency and qualityof software that can be used in anindustrial environment.

\EVIE

PE:PLE

People

The new president of the Society ofElectronic Er Radio Technicians,SERT, is David, The Lord Mottistone,CBE, DL, C.Eng., FIERE, FIPM, thefourth Baron of Mottistone.Following a career in the Army, LordMottistone spent two years withRadio Rentals, followed by hisappointment as the first director ofthe Distributive Industry TrainingBoard in 1969. He has beenassociated with SERT since 1980 andbecame its vice-president in 1984.

Denis 'Sandy' Anderson has beenappointed as Manufacturing Directorof Coutant Electronics, Ilfracombe.

The Plessey Company PLC hasappointed Mr Alan Jones, MA,C.Eng., MIProdE, to the newlycreated position of InternationalDirector of the parent company withresponsibility for Plessey's operationsoutside Europe and North America.

Mr J C C Browne has beenappointed Chief Executive designateof British Telecom Broadband Ser-vices, the division responsible fordeveloping the company's interest incable television and associatedservices.

Circaprint Holdings PLC, manufac-turers of high -quality printed -circuitboards for the electronics industry,have announced thatMr Lawrence Clifford has beenappointed Joint Managing Director.

TMC Limited, the telecommuni-cations company of Philips in theUK, has announced the appointmentof Mr John J Owens as PlantDirector.

Mr Alan A Clark has been appointedas Managing Director fo VintenAvionic Systems Limited, previouslyknown as S. Davall Et Sons Ltd, ofPerivale, Middlesex.

5-19

Shining a light on newtechnologyThe information revolution of thepast few years has quickly turned thedisciplines of electro-optical com-ponents and optical systems intomultimillion pound businesses.New uses for light based systems arecontinually being found in areas suchas medicine, telecommunications,image processing, process industryanalysis, remote sensing, and prod-uct testing and measurement.Among the more exotic uses areapplications in the emerging gener-ations of robots and airborne missilesthat can alter their behaviour or theircourse in response to what they 'see'around them. They do this by rapidcomputer analysis of incoming infor-mation about their environment, fol-lowed by almost instantaneous newcommands to their drives andguidance systems.In telecommunications, BritishTelecom is now replacing large sec-tions of Britain's trunk network withoptical fibre lines. These hair -thinstrands of glass can simultaneouslycarry - in digital format - voice

data, computer data, pictures, andfacsimile.

Laser powerAnd, perhaps most exciting of all,medical specialists are beginning touse light in the form of lasers forregular high precision microsurgery.Electro-optics in many forms is anarea in which British research anddevelopment have blossomed -particularly in laser technology. Fol-lowing research by scientists at theUnited Kingdom Atomic EnergyAuthority research laboratories atHarwell, for instance, equipment isnow commercially available foraccurately measuring the compo-sition and temperature of gasesinside chemical reactors.The technique involves extracting asmall sample of the gas from thereactor and passing through it thelight from three laser beams. Theresulting light beam from the threelasers intersecting at the sample isanalysed to determine gas composi-tion and temperature up to about5000 K with a 1 to 2 per cent error,according to Harwell.

elektor may 1985

The coherent Stokes Raman scatter-ing technique is the result of morethan three years' research financedby the Department of Trade andIndustry. Hardware and software forthe system are available from EpsilonResearch of Rugby.

Beams and dyeThe major benefit of this lasersystem over methods used to date isthe non-invasive nature of thebeams. As the lasers do not disturbthe reactor environment, with thesample typically taken by adding asmall cylindrical extension with win-dows to the reactor, the analysisresults are more accurate thanintrusive methods.The Epsilon system is based on aneodymium -doped yttrium aluminiumgarnet (YAG) laser which producesinfrared pulses converted into greenlight. Two-thirds of the light is splitinto two parallel beams and focusedon the gas sample, together with theremaining third, which has beenpassed through a dye to change itscolour.The colour of the resulting lightdepends on the dye used in thesystems, which is chosen to suit thegas being analysed.Electro-optics can provide equivalentaccuracies for more establishedengineering problems such as align-ment of rotating shafts, with lasersnow being adopted to check bothangularity and parallelism of shaftsused in equipment such as highspeed turbo -generators.INA Bearing of Sutton Coldfield, hasjust introduced such an alignmentsystem called Optalign. This is saidto allow rapid and extremely precisealignment, with a resolution of aslittle as 1µm in both vertical andhorizontal planes. And as there is no'sag' in the laser beam, the systemcan be used for very long span align-ment of so-called jack shaftassemblies.

Four componentsUnder normal circumstances, deter -

Harwell scientists work on a non -intrusive laser system that is nowavailable from Epsilon Research foranalysis of conditions inside chemicalreactors.

5-20

elektor may 1985

mining the magnitude of the twomain alignment parameters - paral-lel offset and angular misalignment- is complex and time consuming,requiring repetitive checks with dialtest indicators and feeler gaugesafter each attempt at alignment. INAsays that Optalign overcomes theseproblems.Optalign comprises four main com-ponents. They are a low power laserand receiver unit, a reflector prism, ahand-held beam finder, and amicroprocessor with special softwareand a graphic display device foralignment data.With supplied brackets and clamps,the laser unit is fitted to one of theshafts to be aligned and the reflectorprism is clamped to the other shaft.The brackets have integral, sensitivespirit levels set mutually perpen-dicular.The technique is based on the factthat when the shafts are aligned, thedistances measured between twoplanes perpendicular to the axialplanes of the shafts are the same atpositions 90 degrees around theshafts.

Engineering applicationsOnce the beam sensor has beenused with the computer control toproduce coordinate datum positions,the shafts are rotated through 90degree increments and misalignmentreadings are automatically taken bypressing a key. The display thenshows the corrective alignmentaction needed.Photo -electric controls of severalforms are also becoming widely usedin engineering, typically for 'sensing'what is happening inside a machineor process. Installing such photo-electric systems in either confined ordirty spaces can cause problems,however.By designing a photo -electric controlwith an optical fibre lead, Cambridgebased Visolux is helping to overcomethe difficulties of tight or inaccessiblemountings.Visolux's KSU-LL is direct currentoperated and for use with LC seriesoptical fibres, using a gallium -arsenide light emitting diode totransmit the modulated light alongthe lead. Flexible, with an optimumlength of 1 m, the lead facilitates thesiting of a small detection point inpositions where it would be imposs-ible to fit a conventional photo-electric control, according to Visolux.

Sensitivity deviceA quick action release on the controlunit allows the user to convert theoptical fibre lead between a single

path light switch mode and a reflec-tion light scanner function.The company says an important partof the system is that the sensingdistance can be varied with a sensi-tivity device. This means that thescanner range can be reduced - forexample, to avoid picking up inter-ference from background materials.The demand for data collection andtransmission through optical mediahas given a major boost to theoptical fibre industry.With new customers seeking thefinest possible tolerances on fibre tominimize losses in data transmission,the industry has had to raise qualitylevels.The successful handling, splicing,and operation of optical fibresdepends on the maintenance of fixedvalues for overall diameter, corediameter, ellipticity, and concen-tricity. From Vickers Instruments,based at York, comes a completesystem for monitoring fibregeometries, called Fibercheck.

Measurment of fibre connectorsThe system comprises lightgenerating equipment, a range oflenses and filters, micrometer andnumerical aperture adjustment equip-ment, and a video system withrelated image manipulation andmeasurement controls.By comparing images of fibres, thephysical parameters of the samplescan be determined. As well as hand-ling monomode and multimodefibres, Fibercheck can measure theend face geometry of optical fibreconnectors. An intensity profiledisplay can be set to measurebetween zero and 100 per cent inten-sity to accommodate varyingindustry standards.Fibercheck uses direct physicalmeasurement techniques rather thancomputer processing of a videosignal. Vickers says measurementsettings are made with a televisionmonitor with gives a clear picture of

Insight Vision Systems' compactVidicon system for maintenance workon sewers and pipework.

a fibre or ferrule end. With a littletraining, operators can learn to makerapid, precise measurements.Such is the sophistication of latestclosed circuit television systems thatthey can be used to provide infor-mation leading to substantial savingsmade possible by preventive andspeedy maintenance.

Tiny television cameraA typical system from Insight VisionSystems of Malvern, is the 75 seriesaimed at water authorities, localgovernment, and maintenanceengineers charged with responsibilityfor drains, sewers, and water mains.The system is based on a miniaturetelevision camera, which is fed alongpipelines to give a picture on a con-trol console on the surface. Thelighting and control system isclaimed by Insight to be aninnovative design giving optimumillumination of pipelines.The control console is based on a225 mm television monitor and con-trols all camera functions, includingfocus, near and far lighting, andmanual and automatic iris. Plug -onattachments available for the cameracan also be operated from theconsole.The camera has 600 lines of pictureheight with a Vidicon tube providingvarious options. The lens is a 12.5 to75 mm, f1.8 zoom, and the cameraweighs less than 800 g. It consumesless than 2 W of power.V Wyman (asst editor The Engineer)(LPS)

5-21

A/D and DiA conversionetektor may 1985

Figure 1. A commercial8 -bit data converter boardfor processing videosignals.

An analogue -to -digital con-verter is also referred to asan encoder, as a digitizer, oras a quantizer.A digital -to -analogue con-verter is often called amonolithic D/A converterand is also known as adecoder.

a review of thestate of the art

Figure 2. Simple data processing system. Note thatthe analogue data arealso electrical signals.

. ' ..a.

10 ''' : ." . iSr . ,..

. 1. ''..1,:. * ..a.

.... ..11V.., 1, 11, 1 I I .

;xCCZ.1.1,1' t Z'

21.. ''''''-- A/D and...-,,,_

D/A conversionAll computers, except analogue types, work with digital signals.Unfortunately, most information that needs to be processed incomputers is of a continuously varying (= analogue) character:pressure; temperature; speed; acceleration; luminous flux; frequency;voltage; and many more. Before such information can be processedby the computer, it has to be translated into binary digits (=bits).Once the information has been processed, the digital output of thecomputer must often be converted into analogue signals. Theseanalogue -to -digital (A/D) and digital -to -analogue (D/A) conversionsare accomplished by special ICs, which are normally located in thecomputer system as input ports (A/D) or output ports (D/A). Thisarticle aims at showing what all this involves and the state of the art.

The data book of a major semiconductormanufacturer states in its introduction:"This book gives 34 types of A/D con-verter circuits; if none of these meets withyour requirements, there are 92 furthertypes available. Information on these willbe supplied upon request". The main dif-ferences between all these types lie incircuit techniques, application, andpackaging. This last aspect will not bedealt with in this article, because it hardlyaffects the designer.

Data processingAs an example of what is involved in the

2

Vaal

t..rdaanta.ad a a

arrtpi if

dual conversion process, let us considerthe simple data processing system shownin figure 1, and let us assume that thesensor is the object lens of an electroniccamera. The amount of light captured bythe lens is translated in the camera intocontinuously varying electrical signals,which are amplified, filtered, and thenconverted into digital signals. The com-puter stores and processes the informationand, based on this, generates a digitalsignal that is converted into an analoguesignal, which, after amplification, is usedto focus the object lens.

Analogue -to -digital converterSemiconductor manufacturers proudlyemphasize the 'speed' of their particularproduct. But what does a '100 MHz conver-sion rate' or a '100 ns conversion time'really mean? What criteria should we con-sider in these converter circuits? In ouropinion, the following are of primeimportance. Detailed information as to the input and

output signals (range of analoguesignals; source and load impedances;binary coding; logic levels). Conversion rate (this is not the

reciprocal of the conversion time).I Information on the control interfaces.III Permissible error rate. Effect of external factors (particularly

temperature) on the accuracy.

5-22

Additionally, the following should also beknown.III Range, resolution, and filtering of the

input signal. Permissible non -linearity. Required stability of the supply

voltage(s).Quite a number of characteristics to lookat! So, let us look at the various conversiontechniques, their pros and cons, and onthat basis formulate possible applications.First, the dual slope technique, wellknown for its use in digital voltmeterapplications. In this technique, the conver-sion cycle consists of two basic timeperiods. Period tl results from the inte-gration during a given time interval of theinput voltage: the output voltage, U.. ofthe integrator is directly proportional tothe input voltage. U. At the end of periodti, a reference voltage, U,, is applied tothe integrator, so that U. decreases. Theintegration continues until U. reaches thezero reference level. The time taken by U.to do this, t2, is the down ramp period.Period ti is constant for each conversiontime, while t, depends on U. Afterintegration, it is found thatU=Ut2/tiIf, therefore, t1 and t2 are measured, andU. is accurately known, the level of theanalogue input voltage can bedetermined.The advantages of circuits using this tech-nique are: inherent accuracy; excellentnoise suppression, no need for latches; noneed for high stability or low toleranceexternal components; coding errors can-not occur, and last, but not least, low cost.The principal drawback is the low conver-sion rate: 3...100 conversions per second.In digital voltmeter applications all theadvantages count, while the drawbackdoes not matter at all.The second conversion method is basedon successive approximation. This (serial)technique is not as fast as some others,but its low cost, ease of construction, andsystem operational features make it themost widely used method in use today.The successive approximation system usesa digital -to -analogue converter in a feed-back loop, and, in operation, comparesthe bits of this converter one at a time,starting with the most significant bit (MSB).As each bit is compared, the output of thecomparator indicates whether theanalogue input is smaller or greater thanthe output of the D/A converter. After allthe bits of the D/A converter have beentried, the conversion cycle is complete,and another is started. A description ofthe practical use of this system can befound in digitizer elsewhere in this issue.The principal advantage of this system isits relatively high speed of some 105 con-versions per second. Its drawbacks arethe need for high stability external com-ponents; coding errors are possible;latches are required; automatic zero set-ting is difficult; higher cost. However,these disadvantages are negated to alarge extent by constructing the A/D con-

verter on the same chip as the sample -and -hold amplifier, the reference voltagesources; circuits for automatic zero setting,and so on.The third system, which has only come tothe fore in the last year or so, is calledparallel or flash encoding. This methodrequires 2n-1 comparators for n bits ofinformation. Because so manycomparatorsare required, it was not until recentadvances in the state of the art of ICs thatall of these could be accommodated onone chip. A typical example of anencoder based on this technique isillustrated in figure 1 (in which only one ofthe ICs is the A/D converter, of course).The interface board shown is primarilyused in meteorological radar equipmentand in robotics. Appropriate graphics pro-cessors are available. Its data acquisitionrate lies a 5 MHz; the resolution is 8 bits;and the conversion time is 200 ns. Asimilar interface, containing a DMA (directmemory access) control circuit, is compat-ible with the bus for the 6809 and 68008processors.Details of the A/D converter IC used infigure 1 are shown in figure 3. The input

3CE2

PH

CLK

V00

Analog VoD

+REF

-REFRI

R2

R3

R4

v,

CEI

OFW

B8

87

B6

85

B4

B3

B2

BI

Digital Vss

Analog V

V., 0 vy a e, v.,

0 0 C3

A/D and D/A conversionelektor may 1985

Figure 3. Block diagramand pinout of a parallel orflash converter.

USR

il4 it

64. <

APCODER 3I W

I f111

I LATC.f S

001....PAT0AS IOU

4

1-

P 7

.30&A

.2C3

<

Fit

TOooar: 44 AT 0 4,5

25I P4,12,11re

ArV.1t-crt

2

1!;I =

Ate

5 2

Eroe

CO..E AS 74

CE

TEO,

PS

11I.

t5

5.

TF

85050.3

5-23

A/D and D/A conversionelektor may 1985

Figure 4. Encoding anddecoding (al leadinevitably to quantizationerrors lb).

Figure 6. Illustrating a dif-ferential linearity error of-LSB/2. When the erroris negated, each conver-sion stage has an outputof exactly Q.

Figure 5. In a practicalA/D converter, offseterrors la). gain errors lb),and linearity errors lc)occur. Their combinedeffects result in a quan-tization error.

5ao

1 1:0I-

'01

100

o 01 010CC 00,

CO)II

`,,FS 5

Offset Error

ANALOG INPUT (VOLTS)

bGain Error -1

0UI-0.

I-0cc4z

111

110

101

103

On

010

001

0

110

101

ICO

Oft

010

aut0:0

',F5 Fs

ANALOG INPUT (VOLTS)

LinearityError

FS

ANALOG INPUT (VOLTS)

Error 5i.7,11

74'550604

signal at pin 12 is converted in two stages.The first stage, consisting of eight com-parators, eight latches, an encoder, andfour output buffers, generates the threemost significant bits (MSBs). The five leastsignificant bits (LSBs) are produced by thesecond stage which comprises thirty-twocomparators, thirty-two latches, anencoder, and five output buffers. Powerdissipation in this two -stage arrangementis smaller than in single conversion. Froma circuit design point of view, the flashencoder IC provides, of course, singleD/A conversion.The reference voltage for the 256 resistorsand forty switching stages is appliedbetween pins 6 and 7. The voltage take -offpoints are connected to the invertinginputs of the forty comparators.Then there are four control inputs: CLK(clock); PH (clock polarity); CE1 (when thisterminal is logic 1, Bl...B8 provide athree -state output); and CE2 (when this ter-minal is logic 0, Bl...B8 and the OFWbuffer - pin 23 - provide a three -stateoutput).The OFW output may be used as a ninthbit when two of these ICs are cascaded.As an example, when the input voltage is2.56 V. and the reference voltage is 5.12 V,the output code is 10 000 000. A completeconversion cycle takes place during oneclock pulse.The attraction of this technique is, ofcourse, the very high conversion rate of5 MHz. Its drawback remains that a con-verter still uses more circuits, andtherefore space, than a converter usingthe other two techniques.

Quantization errorThis is a fundamental error associatedwith dividing a continuously varying(analogue) signal into a finite number of

d 20

"20O

-> 0

1/2 0

-0

-20

ANALOG INPUT (VOLTS)

FS= Full Scale85050-5

LS

6111

W 1100U

101

100

0011

a 010

00

- 7

AQ (+14 LSBDifferential Linearity

/ +- Error)

ri300 (-30 LSBDifferential LinearityError)

FSR=

2n

ANALOG INPUT (VOLTS)

FS = Full Scale850506

FS

bits; its maximum value is ±Q/2 (whereQ =LSB).As an example, figure 4 shows inschematic form the conversion of a rampsignal from analogue to digital and backagain to analogue. When the output signalof the decoder is deducted from theoriginal signal, or vice versa, there is anerror signal, which may be considered asthe r.ms. output of a noise generator,Ug=Q/f12, superimposed on the inputsignal. Because of that, the effect is alsosometimes called quantization noise.This property is, of course, of particularinterest in the selection of A/D or D/Aconverter ICs for use in PCM (pulse codemodulation) audio circuits. Table 1 lists themost important parameters. From these, itshould be clear why in this case ICs with16 -bit resolution should be chosen(although 14 -bit converters are sometimesused): they have a signal-to-noise ratio of107.1 dB and a dynamic range of 96.3 dB.

Linearity, gain, and offset errorsCurves representing these three errorsare given in figure 5. Taken in conjunc-tion, they result in a quantization error thatdoes not look as uniform as that infigure 4. However, this combined error isno longer caused by the system alone,like the quantization error, but is causedmainly by production techniques andtemperature -dependent external factors.The offset error is the shift on the x axisof the actual conversion characteristic ascompared with the ideal one (whichwould, of course, go through zero).The gain error is, strictly speaking, ascaling error: it is the difference in slopebetween the actual and the ideal transfercharacteristic. (This assumes that the offseterror has been cancelled out).Non -linearity is interpreted in two ways.In the fast, it is seen as an integrallinearity error (figure 5c), i.e., the maxi-mum deviation from a straight line drawnbetween the end points of the converter'stransfer characteristic. In the other, it isconsidered a differential linearity error(figure 6), La, the maximum deviation ofeach conversion step from its ideal value,which is the FSR (full scale range) dividedby 2', where n is the resolution in bits.

5-24

When selecting converter ICs, you must,of course, not treat these values as absol-ute. For instance, for an A/D converter forPCM audio, the maximum distortion figureis of far greater importance than the maxi-mum linearity error!

Digital -to -analogue converterD/A conversion can be effected by anumber of methods, of which two are con-sidered. The first is the current outputsystem, schematically shown in figure 7.Here, the bits are converted into constantcurrents, /,; and lo". When the input bit islogic 1 or logic 0, the two currents areequal, so that -the output of the differentialamplifier to which the currents are fed is0 V. If the currents are not the same, theoutput of the amplifier has a finite value.Let us consider an example based onfigure 7, whereby a digital audio signal isconverted to an analogue one. The con-verter IC is, of course, a 16 -bit type. Theoutput voltage of the differential amplifieris applied to a sample -and -hold stagewhich effectively suppresses any glitch.Then follows a low-pass filter whichremoves any scanning noise, and finallythe analogue signal appears at the output.This type of arrangement, which can befound in CD (compact disc) players, forinstance, has a maximum distortion factorof only 0.005 per cent over a bandwidth of20 kHz and a dynamic range of 96 dB.Sixteen -bit D/A converters are availablewhich combine the current output andR -2R techniques. The four most significantbits (MSBs) are then processed by the out-put current method and the four leastsignificant bits (LSBs) by the R -2R tech-nique. According to manufacturers'specifications, this reduces both the dif-ferential and the integral linearity errors tovalues well below those associated withother conversion systems.The second technique is based on anR -2R resistive ladder network as shown infigure 8. Only one branch of the ladder isconnected to //REF at a time, and theremaining ones axe earthed. A current isproduced in each branch in succession(the switches are electronic types). Thiscurrent flows through the ladder and isdivided by 2 at each junction. Therefore,the contributory current from each branchflowing through load RA is binarilyweighted in accordance with the numberof junctions through which it has passed.The resulting voltage produced across RAis thereforeUA -'TREF/21+ UREF/22+ UREF/2nwhere n is the number of branches.This voltage is compared, in steps, withthe digital input voltage (see also thearticle digitizer elsewhere in this issue).

Final pointsIn your search for the solution to yourconversion problem, you may not be ableto find the ideal. You will, therefore, haveto come to a compromise, particularly asregards the cost, because prices are high!Sony, for instance, lists a 100 MHz A/D

Table 1.

Resolution(n)

States(2")

BinaryWeight

(2-n)Q for

10 V FSS/N Ratio

(dB)

DynamicRange

(dB)

Max Outputfor

10 V FS IV)

4 16 0,0625 0,625 V 34.9 24.1 9.37506 64 0.0156 0.156 V 46.9 36.1 9.84408 256 0.00391 39.1 mV 58.9 48.2 9.9609

10 1024 0.000977 9.76 mV 71.0 60.2 9.990212 4096 0.000244 2.44 mV 83.0 72.2 9.997614 16384 0.0000610 610 NV 95.1 84.3 9.999416 65536 0.0000153 153 i4V 107.1 96.3 9.9998

FS = full scale

converter board at around £3000! Perhapsyou had better look at the digitizerfeatured elsewhere in this issue!

Literature:Full Line Catalog 1984 and ApplicationNotesMicro Power Systems, Santa Clara, USAData Acquisition HandbookIntersil, Cupertino, USAA/D and D/A Conversion ManualMotorolaData Book of Analogue DevicesBurr -Brown; Harris; National Semicon-ductorA/D and D/A conversionElektor, March 1982, pp. 3-43 to 3-46

7

16 titCurrent OutputD/A converter

ore

controlcircuit

1

sampleand -hold

circuit

E5Cr-,a 7

8

Table 1. Parameters fordata conversion

Glitch or skew is a spuriouspulse of very short durationcaused by the switchingfrom one conversion state tothe next and may beaccepted as a bit.

Figure 7. Example of D/Aconversion with high res-olution: the 16 -bit PCMaudio signal is firstencoded and thendecoded.

20 kHzlow-pass

filter

Figure 8. Block diagramillustrating the R -2Rtechnique.

5-25

programmable timerelektor may 1985

M. Kuijk

with a host offacilities

programmabletimer

This truly versatile timeroffers eight switched outputs that

enable each day of the year to beprogrammed; repeat functions; the facility to

access no fewer than 149 multiple, or 199 single, switchingprograms; an eternal calendar that tells you in a jiff on which

day 17 January 2011 will fall; a front panel with built-in keypadswitches; and much more...

To start with, we want to put your mind atrest about the timer being difficult tooperate with all those facilities. It hasbeen designed with ease of operation inmind, so that after half an hour's initiationyou will know the timer inside out!The timer shows, of course, the correcttime and date. Leap years have been pre-programmed, so you will never have to doanything about these. There are eight out-puts that can be switched manually orautomatically; the output status is alwaysdisplayed on the front panel.The eternal calendar is programmed up to1 January 2100. If you want to know onwhich day your birthday falls next year,just key in the date and the DAY LEDs willshow you at once the corresponding day.The outputs of the timer can be pro-grammed in numerous ways, as a fewexamples will show. On 16 August, output3 switches on from 12 noon till 1 p.m. On7 May, outputs 1, 2, and 8 switch on atmidnight, and switch off again on 12 Mayat 7.30 a.m. These are single switchingtimes, as there is only one switch -on time

and one switch -off time per program. Thenumber of outputs that cart be switchedby each program is 1...8. The timer canstore up to 199 of these single programs.Multiple programs are also possible. Forexample, outputs 3 and 4 switch on everyday at 7.30 a.m. in February, March, andDecember, and switch off again at 8 a.m.the same day. Outputs 1, 6, and 7 switchon every Saturday and Sunday in June andJuly between 12 noon and 1 p.m. Output 2switches on between 7 p.m. and midnighton the first day of every month, but only ifthat day falls on a Monday. Output 5switches on from 9 a.m. till 5 p.m. on 2, 12,23. 29, and 30 September. The timer canstore up to 149 of these multiple pro-grams. Where single and multiple pro-grams are mixed, the total number ofprograms will be 149...199 depending onthe mix. The timer will indicate when thememories are full.

Circuit descriptionAlthough the timer contains a fair number

5-26

of components, there is not all that muchto be said about the circuit. Essentially,the timer consists of a small computer andthe electronics for controlling the displaysand LEDs.The CPU (central processing unit), IC1, isa type 6809. The timer program is con-tained in IC3. a type 2732 EPROM. Dataare stored in a CMOS RAM (randomaccess memory), IC2, while data com-munication is controlled by IC4, a type6522 VIA (versatile interface adapter).The reset (RES) input of the CPU is con-nected to an RC network that ensures theresetting of the circuit at each power on.The FIRQ (fast interrupt request) input ofthe CPU is connected to the secondarywinding of the mains transformer, so that afrequency of 50 Hz exists at this pin. This

frequency is used as a time reference forthe clock. In case of mains failure, theprogram automatically arranges for thetimer to continue operating from built-inNiCd cells and crystal Xl. At the sametime, the displays are switched off tominimize current consumption.Address decoding has been kept simple.Address decoder IC5 uses address linesAll...A13. The RAM, IC2, is enabled byoutput "0"; the EPROM. IC3, by outputs"6" and "7"; and the VIA, IC4, by output"2". Latch IC6, containing the status of theeight switched outputs, is enabled by "3"via gates NI and N4. The latch is followedby a number of buffers, N5...N12, whoseoutputs are intended to be connected torelays for the switching of any equipmentcontrolled by the timer. Each buffer can

1

/11 ... N4 .1C7 7.1/500ID... N11 .1173. MN 2003N17... NU.1010. U11120031115 .1225.1C11. ULM 2003

O1.(3, an 40 >21. O..11 . 3 Cliel 3 GO .1

.13 ...a 313 UM .11.1.331.DU 1 nt =3..3 CU 31.3.30.3. nu .13 rut Z. .1.013..3 u .3 MU SAT

0.3.....RiT 631. Oa =34 TUE

131

13 .313333U333.1U .402 1.311.1113 .11 Os.

3. -I EU,SO .3344. imeas rut

Tel

U SUM.

113SU 3.133TS ULM11. VelaUs %CU

5V

BC 54713

; a tlCael1V24.00 e.JA

7:1aU

V

8.34,1123

INalaax,

tzsszsla 2 dit,VIA

IC4

T T .

O77 H

er.? 4.4 - -

VOTTlgil

'I

LOT LD441 7792;7751

0

T2 TS a SC ELI.BC EAT

programmable timerelektor may 1985

Figure 1. The circuitdiagram of the program-mable timer.

-

- 5 .

'01:11Nal

5-27

programmable timerelektor may 1985

Figure 2. The printed cir-cuit board for the displaysection.

BCD = binary codeddecimal

Figure 3. The printed cir-cuit board for the pro-cessor section.

B5047-2

switch up to 80 mA. Note that the outputof an active buffer is logic low so that anyrelay must be connected between thepositive supply line and the output of abuffer . On the pcb there is, therefore, a+5 V terminal adjacent to each buffer out-put pin. LEDs D3...D10 indicate the out-puts status of the buffers.

The remaining LEDs, DU...DM. and thedisplays are controlled by port linesPAO...PA7 and PB0...PB7 of the VIA,IC4. Lines PB5...PB7 are additionally con-nected to a BCD -to -decimal decoder, IC8.Outputs "4"..."7" of this decoder are usedfor the key matrix, while outputs .'0"..."3"drive transistors T2...T5. which in turnarrange the multiplexing of the displays

5-28

and LEDs D11... D34. The segments of thedisplays are controlled by gatesN19...N25; the LEDs by gates N13...N18.The keyboard matrix contains a lockingswitch, S17, which ensures that the pro-grams cannot be altered by unauthorizedpersons. It is obvious that, unless it is keyoperated, this switch must be situated outof sight.

The power supply contains two 5 Vregulators: one for the supply line to theLEDs and displays, and the other for theremainder of the circuit. When the mainsfails, the power to LD1...LD4 andD3...D34 is switched off. Apart frombeing necessary for the total current con-sumption of the clock, the regulators alsoobviate feedback to the control elec-

programmable timere(ektor may 1985

Parts list

Resistors:

R1=1202R2,R3 = 22 kR4,R36...R39 = 1 kR5 = 4k7R6...R10 = 2k2R11...R18 = 330R19...R31 = 47R32...R35 = 390 Q

Capacitors:

C1...C4 = 47 nC5 = 2200 i'!25 VC6...C9,C15...C19,C21 =

100 nCIO = 56 nC11,C20 = 100 p/10 VC12,C13 = 22 pC14 = 10 p/10 V

Semiconductors:DI,D37... D40 = 1N4001D2,D35,D36 = 1N4148D3...D13,D15...D34 =LED, red, 5 mm

D14 = LED, red. 3 mmT1 = BC 547BT2._ .T5 = BC 638 or 6401C1 = 6809IC2 = 61161C3 = 2732IC4 = A577IC5,1C8 = 74LS145IC6 = 74LS374IC7 = 74LS001C9,1C10,IC11 = ULN 2003IC12,1C13 = 7805

Miscellaneous:

Sl...S16 = sixteen -waykeypad in front panel

S17 = single pole, singleway switch, preferable keyoperated

Fl = fuse, 100 mA, delayedaction, with holder

LD1...LD4 = sevensegment display(Regisbrook Ltd - Unit 5,Horseshoe Park,Pangbourne, Berks. Phone:(073 571 4841

X1 = crystal, 4 MHz. withHC18U or HC25U case

Trl = mains transformer,secondary 10 V/1.5 A

Connector to terminatecable from keypad; e.g.;Molex 7583-CNA-08

Front panel 85047 -165 x 90 mm

PCB 85047-1 -125 x 105 mm

PCB 85047-2 -125 x 105 mm

NiCd cells (7 off)1.2 V/0.5 Ah

5-29

programmable timerelektor may 1985

Figure 4. Sketch of apossible construction ofthe programmable timer.

6

Figure 6. Fit the voltageregulators like this.

4

tronics of pulses caused by the multiplex-ing of the displays and LEDs. The back-upNiCd battery, providing an emergencysupply via DI, is trickle charged via RIduring normal mains operation. The cur-rent consumption during mains failureamounts to 250...300 mA, so that the bat-tery will be able to drive the timer forabout an hour.

ConstructionThe timer is best constructed in a slopingcase as shown in figure 4; the dimensionsof the two pcbs are 125 x 105 mm. Onepcb contains the displays, LEDs, and rel-evant driver stages (figure 2), while theother houses the remainder of the circuit(figure 3).First complete the processor pcb; usesockets for the ICs. The wire links shouldbe of not too thin wire. The regulator ICsmust be fitted at the track side of the printwith their plastic side towards the edge ofthe board. After they have been soldered,bend them towards the edge of the boardin such a way that their metal edge isabout 10 mm (2,, in) off the underside ofthe board.Next, complete the display board; againuse sockets for the ICs and not too thinwire for the links. The LEDs must bemounted on a level with the displays.The case should be of dimensionssuitable for the front panel, which containsall the key switches. The front panel isdelivered with a template for the prep-aration of the sloping panel of the case.The display board is mounted directly

behind the sloping panel in such a waythat the displays and LEDs just do not pro-trude through the holes you have drilledand filed. The processor board is fitted onnylon spacers (to prevent short circuits) tothe base panel just under the displayboard. The mains transformer is fittedtowards the rear of the case. Lockingswitch S17 (unless key operated), themains input connector, the fuse holder.and possibly the terminals of the switchedoutputs should be fitted in the rear panel.The holder for the NiCd battery is best fit-ted alongside the processor board in thebottom. The 31 connections between thetwo pcbs are best made in flat ribboncable. The metal flange of both voltageregulators must be screwed to the basepanel of the case: use heat conductingpaste between the flange and the case.Finally, solder the rest of the wiring inplace.Ventilation holes should be drilled (unlessalready provided) in both the base andthe back panels. Also, fit four rubber feetto ensure good ventilation.When the case is ready, fit the front panel:first remove the backing paper, push thekeyboard cable through the slot, and thenstick the panel in the right place. Locate itcarefully, because once it is stuck, it can-not be shifted. It is, therefore, advisable todo a dry run. Connect the keyboard cableto the display, and the timer is ready foruse.

Switching of external equipmentThere is ample room left in the case for

5-30

Table 1. The hex dump of the program for the timer.000- :: -,7 :F 01 ED SI EC 400- FF FF FF FF FF == FF FF BOO- 01 26 02 OC AO 7E aa 22 COO- ED 05 ea 07 =. SS II OF003- :7 :6 F7 07 OF 10 CE 402- FF FF FE FF FF == FF FF 808- 86 BO C6 00 FD 10 00 F7 aoa- 92 79 di OE 26 14 CI 07010- -20 .10 FE 66 15 BF 10 06 24 F7 66 01 54 2B 02 48410- FF FF FF FF FF FF FF FF 810- 18 00 OC FA 96 FA 91 04 210-018- OC AC OC AD 86 40 67 10 416- FF FF FF Fr FF FF FF FF ma- 26 04 OC A3 OF FA 96 20 718- 20 FA AS 07 A, 07 47 97020- 08 86 CO 97 10 OE IC EF 420- 96 92 BE 76 97 46 216 9B 620- 04 78 36 BO 26 00 FD 10 C20- A7 39 61 06 26 ZO 60 OF02S- OC ea 86 oa 97 Ca OF 10 428- DS 97 DA 96 87 21 07 25 822- 0: 77 DD 96 DD at 04 27 C18- 77 OS EC 02 DD B2 39 DC070- 04 BD 7E SO 130 32 60 DC 470- 05 ES 93 19 20 F7 98 DA 67 0 CO-0-.: F7, 72 CB 7E 71 80 7F 92 ED OB BD 04 40 79 OF072- 92 DD Fa 96 09 97 AE 08 4:0- 97 DA 96 92 81 02 22 OA 878- 0- -7 86 60 OF OD 28 20 232- 52 OF 53 SE 07 77 67 ED040- 01 07 B7 DC AC 16 69 OD 440- on 09 26 06 36 DA 69 06 r.840- - :, 00F6 10 01 CC DD 240- 39 43 9622 415 79 91 O9O 40- I.: 90 7? DO CI 02 27 OD 448- 97 DA 76 DA al 07 04 84a- 54 :4 IC OC DO 54 24 17 249- 26 FB BD EB 27 05 EC 0/425

650- .0: .-.-, 54 =4 10 OC DD 54 C50- DD 92 75 DC BM ED OA BD050- Cl 09 =7 04 CF B2 OF 67 450- SE F9 30 F8 4C Co FE D7058- BD 29 69 26 E6 DC 82 16 453- 07 40 27 06 10 01 09 A7 asa- 24 0- 21 £0 26 60 OC 015 253- 3A 40 77 FF FF Pr FF FF060- 89 DD AC ED 74 00 76 A7 060_ -.0, 0-, 7. C. .0 C. CC pp 860- OF FS 54 25 02 OC FS SE C60- OD F9 26 01 70 7E CI' OD066- 97 AF BD 35 80 OF 64 DC 268- 32 94 96 OD A6 86 77 OF 268- CS 26 21 OD 24 27 01 39070- AA DD 82 86 07 ED 79 60 470- F: F0 i =- E.- :,0 7, 7.0 670- OF DE 61 OF 706 OE 66 40 270- 02 D2 A6 OC 47 60 0C BB078- 26 06 DC 92 DO AA OF A9 272- 87 10 00 1116 10 01 12 44 779- 26 F0 9E C2 70 14 ,F C2080- BD 2£ CO CF 90 20 OA FF 460- OF F:. 7= :, == =- :-- :9 250- 25 02 OC DE OF DD 4F 5F CEO- RE BB 30 14 7F BO 80 37082- FF FP FF FF Fr FF FF FF 4E18- B2 0= r. r- -- .. -. 6C BBB- 43 53 FD 10 02 47 RD 7E CBS- 17 OF 02 39 OD 82 26 01090- FF ED 29 DO CI OA 24 05 470- BD 74 20 :1 4? Fr= FF FF B90- CB B6 10 04 7B OF 09 08 CVO- 39 96 C5 SI 01 26 OC EC093- 80 30 B4 20 F4 53 30 SC Ava- FF FF F.= == == Fe= FF FF eve- 07 OE 06 OS 04 OD 03 02 098- 01 93 94 De BB ED 01 OD040- FO AD 55 20 EC :0 el ao 4A0- FF FF FF 7= =F 7F AF =F SAO- 01 OC OB 00 OA FF FF FF CAO- 70 40 79 96 CS 61 0: 26043- 87 70 CE 30 93 7E 42 37 4AS- Fr FP FF FE FF PP F9 =F 848- FF FF FF FF FF FF FF FF ZAB- 17 EC 02 9a BA 03 99 ED090- 60 OF 94 39 SD 27 11 Cl 480- FF FF FF FF FF FF FF 9,0 Fee- FF FF FF FF FF FF 96 AB CEO- 07 EC 05 72 BC D8 ED EDOFF- 0? 24 OD 86 01 5A 27 03 428- FE FF FF FF FF FF FF FF ass- al IA 26 07 OF F7 at 32 0178- 05 80 :A 40 79 FF FF FF050- 48 20 FA 913 94 97 84 79 420- FF FF FF FF FF FF FF FF 6C0- :6 19 OF AS BE 00 AS 4F CCO- 9E CA OD C4 27 05 60 17O 08- 7E 34 67 FF FF FF OD BO 4CE- FF FF FF FF FF FF FF FF SCS- 60 36 26 07 4C RD OD 31 =2- 26 01 39 OD CS 26 OB OF000- 26 05 18 01 06 90 79 06 400- FF FF FF FF FF FF FF FF 6150- 06 26 F5 96 BO B4 7F 26 COO- 43 OF 42 OC CS EC 18 DO0156- 90 25 03 OF 90 3? as 40 40a- FF F0 =9 FF FF FF FF FF 900- 02 07 F7 79 BD 37 90 Db 203- B2 39 76 C5 al Ot 26 OD0E0- 97 80 OF BI 39 FF FP FP 4E0- FP F7 FF FF FF FF FF FF SE0- AF 26 02 OC AP D6 AC 26 CEO- 03 AS 03 A: OF A4 DC CS0E9- Fr FF FF 9F FF FF FF FF 4E2- FF FF FP FP FF FF FP 7P 352- 02 OC AC Do AD 26 02 OC CES- EC IA DD B2 11 76 CS 81OFO- SE CA OD C4 27 05 60 17 4F0- FF FF FF Fr FE FF FF FF BFO- AD 62 26 E6 86 C4 OF CI CFO- 02 26 OF 03 44 96 Ab 84OF8- 26 01 79 OD C5 26 11 OF 4F8- FF FF FF FF FF FF FF FE EFS- OA 26 06 ES SS C8 10 E7 tea- BP 97 A6 OC C5 EC 1C DO100- A3 OF 72 96 06 84 BF 57 500- 96 AD 61 10 25 02 SB FA 900- 86 31 SC 09 25 A6 El So D00- 92 79 96 C5 SI 03 26 OD108- 46 OC C5 EC IS DD 92 39 sae- OF D5 Ch SO D7 04 40 27 708- 26 02 6F 26 ai 04 26 20 Boa- 46 46 BB CO 97 A6 OC C5110- 96 C5 81 01 26 OD 03 A7 510- 06 04 D4 06 05 20 F7 96 910- D6 AD 31 laC 2E E6 45 DI 010- EC IE DO 82 79 OD 24 27112- 03 A2 OF A4 OC CS EC IA SIO- AC at TO 25 02 88 FA 81 718- AC 26 02 OF AC OD A2 27 Dia- 06 SE C2 70 17 9F CO 9S120- OD 22 79 96 C5 81 02 26 520- 20 25 02 89 FA 61 10 25 720- OE 06 AD CI 02 26 08 216 020- CA 90 0E 00 79 FF FF FF122- 17 07 A4 76 46 88 CO 97 528- 02 88 FA OF CO OF CI OF 928- AC 21 27 26 02 OF AC IA 028- OD FS 26 01 59 9E CA 00170- A6 OF A2 OF AS OC C5 EC --0- BF C6 60 D7 BE 4A 27 OA 930- 01 09 AF 09 AF 103 04 C6 030- C5 26 IF OD C4 26 119 OC118- IC 00 B2 39 76 CS 81 OS saa- 04 BE 06 BF 06 CO 06 CI 079- FD D7 AF 04 A= := 6-: 60 D32- D2 46 16 A7 82 92 C8 26140- 26 OD 03 42 03 A3 OF 44 540- 20 F7 79 FF FF FF FF Pr 940- 24 72 13 04 7: 7 :: D40- FS 9E CA MO 00 9F CA SE148- 02 CS EC IE DO 90 39 OD 543- FF FF FP FP FF FE FF FF 742- 32 31 32 :: 7: 7: 7: 72 D42- CB 30 09 9F CB BD 3D FA150- C4 27 06 9S CS 70 17 9F 550- OC 06 05 02 BA 40 74 02 950- 22 7= 72 7: 7: :2 FF FF D50- OF D2 39 OD FS :6 01 24ISO- CB 7E CA 90 SE 00 79 FF 558- 39 FF FF FF FF FF FF FF 058- FF FE == == == FF FF FF 058- 9E CA 76 CS 26 10 86 01160- Fr FF FF FF FF FF FF FF 560- FF FF FF FF FF FF FF FF 960- 97 57 2: :4 -9 02 0F 93 D60- SA 27 OU 4B 20 FA AB 17160- FF FP FP FF FF FF FF FF 560- FF FF FF FF FF FF FF FF 968- BD 39 DO CI 09 22 12 36 D6a- A7 17 97 FE 39 FF at 01170- FF FF FF FP FF FF FF FF 570- Fr FF FF FF FF FF FF FF 970- 04 OH B2 09 83 4A 26 F9 070- 26 20 BD OF 27 05 EC IS178- FF FF FP FF FF FF FF FF 578- FF FF FF 7F FF FF FF FP 972- DA 92 D7 62 12 12 12 20 073- OD 62 39 DC 82 Ell 19 EDISO- OD D2 26 15 SE DO OD CE 580- FF FF FF FF FF FF FF FF 5E0* 27 CI OA 27 DF Cl 02 26 DSO- 70 FO 39 OF B2 OF E7 86sea- 26 22 86 OA 97 CF 92 88 58E- FF FF FF FF Fr FF FF FF 929- 07 26 FP 39 Cl OB 26 DS Dea- 01 97 B7 BD 39 6E1 SE CA190- :5 OB SE 09 00 SF DO OC 590- FF FF FF FF FF FF FF FF 990- 96 S7 49 49 30 EC 20 E6 DSO- 40 39 Ell 02 26 20 BD OF199- CE 86 10 04 IS SO 22 00 572- FF FF FE FP FE Fr FF FF 972- 86 DI 87 22 CB 42 Eh 216 D72- 27 05 EC IA DD 82 39 DC140- 30 CC 9F DO OA CF 26 E6 540- FF FF FF FF FF FF FF FF 500- DI 93 =5 C4 4C Eh 86 DI 0A0- 92 ED IA BD 30 FO 39 OF1411.. BE 10 04 3S 96 04 97 CF 542- FF FF FF FF FF FF FP Fr 948- 82 22 SD 42 E6 ea DI H2 DAS- B2 OF 83 86 0: 97 87 BD190- 92 CS 22 76 eE 01 00 SF ISO- AP FF FF FF FF FF FF FF 980- 25 B6 BD 32 DO 4F 79 16 080- 39 69 9E CA 40 79 81 03tBa- 00 OF CE 76 CD 4a 153 43 508- FP FP FP FF FF FF FF FF 988- 20 00 57 01 31 01 12 AA 083- 26 11 BD C7 27 05 EC ICICO- 54 94 57 B4 96 CD 97 D7 5C0- FF FF FF FF FF FF FF FF 920- AA 01 31 00 23 00 59 AA DC0- DD B2 39 DC 82 ED IC SOICS- D6 Eil C4 07 26 02 97 FE 5Ce- FF Fr FP FF FF FF FF Fr 9C9- AA 01 12 FF FF FF FF FF 028- 30 FO 39 at 04 22 FB 9D100- 78 24 97 18 00 OF CD BD 500- FF FF FF FF FF FF FF FF 9150- 96 B7 91 02 27 04 81 04 0150- D6 27 05 EC 1E OD 82 79IDS- 75 00 96 10 04 38 12 12 50E- FF FF FE FF FF FF FF FF 708- 26 04 86 AA 97 83 BD 3F 003- DC B2 ED 1E BD 30 FO 391E0- :2 12 12 12 12 12 12 10 MO- FF FF FF Fr FF FF FF FF 9E0- E0 FD 7F DO 66 30 97 196 DEO- BD SE 80 OF C4 OF C5 SE158- 12 12 BO 37 00 70 17 9F SEE- FF FF FF FF FF Fr. FF FF 7E2- 4F 4A 26 FD 06 OF 57 26 DF-O- CA 30 09 7F CA EC 08 00IFO- DO OA CF 26 BS 86 10 04 SF0- FF FF FF FF FF FF FF FF 9F0- F7 OA B6 26 F3 06 OF 53 DFO- 2= 19 SD ZE Z6 79 FF FFIFa- 79 FE FF FF FF F9 FF FF SF3- FE FF FE FE FE FF FF FF SF2- 27 FB 53 9E B2 34 14 CC DF3- FF FF 9E CA 20 17 7F CA200- EC 01 74 D4 26 05 94 D5 600- FF FF FF FF FF FF FF FF 000- AA AA DD 92 ED 27 E0 35 E00- OF C4 OF C5 110 7E GO SC20a- 26 01 57 EC 07 94 FE 26 608- Fr Fr FF FF FF FF FF FF A08- 14 9F 22 37 FF FF FF FF FOB- CH 27 09 24 II 10 CE 00210- OE D4 9F 26 OA EC 05 94 610- FF FF FF FF FF FF FF Fr A10- OD C7 26 OC OC 27 CC 80 E10- AO OF BO 7E 70 91 OC 24216- CO 26 04 es Cl 27 37 96 6I8- FF FF FP FF FF FF FF FF Ala- 00 DD BA OF BC OF HD 39 EIS- 30 10 9C sa 23 ET 90 72220- OF 43 44 07 SA 7F 27 2A 620- FF FF FF FF FF FF FF FF 420- OC C7 96 27 64 OF 61 OA E20- 26 ED ZE SO 35 FF SE CA228- 96 AB 41 09 = 20 22-06 628- FP FF FF FF Fr FF FF FF 422- 26 08 76 C7 SF 06 77 C7 E28- OD C4 27 07 86 F7 6F 26210- 96 AA Ai 06 23 IC 6D OB 630- FF FF FF FF FF FF FF FE A30- 04 SA 06 BB 06 BC 06 BD 570- 4C 22 F9 OF FE OD DS 26238- 26 04 6D OA 27 08 96 49 638- FF FF FF F9 FF FF FF FF A32- 39 FF FE FF FF FF FF FF E38- 03 BD 33 EV 46 17 97 FE240- AI OB 22 oe 25 06 96 AA 640- FF FF FF FF FP FF FF FF 440- SE C2 OD C4 27 05 60 64 E40- 39 FF FF FF FF FF FF FF248- Al OA 24 06 A6 00 94 CD 640- FF FF FF FP FF FF FF FF 442- 26 01 39 00 CS 26 OE OC £49- OF DB OF D9 OF BO OC 80=0- 97 CD 29 FF FF FF FF FF 650- FF FF FF FF FF FF FF FF A50- 2.5 OF AS OF C7 CC 01 10 £50- CC 08 04 DD CA ED 3D FA258- FF Fr Fr FF FF FF FF FF 652- FF FF FF FF FP FF FE FF Asa- 93 FF FO 24 2F 96 CS 91 352- 90 39 DO Cl 04 24 05 BD260- 86 OB 57 BA 86 7F 97 47 660- FF FF FF FF FF FF FF FF 460- 01 26 2F BD 30 10 56 SA 260- 10 57 20 F4 se 20 BC FO2613- DC Fa OD B2 ED 35 DO CI 66a- FF FF FE FF FF FF FE FF A62- A4 01 26 1B 96 BB 44 02 E6E- AD 95 20 EC 30 28 30 FO270- OC 27 09 12 12 07 12 OF 670- FF FF FF FE FF FF FF FF 470- 26 15 56 C7 61 13 26 112 570- 30 FO 3D EC. 70 FA 77 60278- 67 80 7? 69 26 EA 96 92 67S- FF FF F9 FE Fr FE FF FF A78- 60 01 26 10 60 02 26 02 E73- FF FF FF FF FF FF FF FF280- 91 29 25 05 SB 72 19 20 660- FF FF FF FF FF FF FF FF ASO- OC C5 OF 82 12 12 29 96 ESO- CC AA AA DO 82 CC FF FF288- F7 Be 76 DO 56 86 D7 De 698- Fr- FF F9 FE FF FF FF FF AE12- C7 97 B2 39 OC C5 OC CS 588- DO 42 DO A4 110 A6 37 FF290- 81 04 25 05 SS 96 IS 20 690- Fr FF FF FF FF FE FF FF 490- OF C7 96 C5 91 02 26 12 E40- 96 OF 81 OE 26 04 OD DP258- F7 97 09 OD 82 26 OC 96 692- PF FF FF FF FF FE FF FE A72- 621 01 26 OA 6D 02 26 06 E72- 27 01 39 OC 09 80 37 OS2A0- 87 81 18 27 04 81 IS 26 6A0- FF FF FF FF FF FF Fr FF 440- 63 01 96 FO A7 02 OC C5 840- 96 09 97 DC 90 33 Be 86248- 02 OC 09 96 83 ai 16 26 64580 FF FF FF F9 FF-FF FP FF AA3- OF C7 96 CS at 00 26 57 E48- FF 97 FE BD 33 E0 BD 115290- 06 D6 DB CS 02 D7 DB 61 630- FF FF 200 FF FF FF FF FF FSO OF AU 03 47 OF 42 EC 07 eso- FA 9E CS 9C CA 27 04 OAlea- 20 26 06 06 02 CS 06 D7 686- 00 03 03 06 01 0406 02 A99- 10 a: Fr FF 26 02 EC OS 383- DC 26 F7 96 OA 97 DC 20000- DB 03 A2 03 43 66 FF 57 620- 05 00 00 00 00 00 00 00 KO- 10 63 FF FE 24 SD BD 7A ECO- 23 OF DB 59 FF FF FF FF222- 47 39 FF FF FF Fr Fr FF 603- 03 OS 00 00 00.00 00 00 423- 10 96 BA A4 03 26 2F 96 ECEI- 26 06 30 83 00 E0 96 06200- 96 87 61 01 26 20 GE 24 600- 00 01 02 00 05 06 00 01 ADO- BB A4 04 26 29 96 BC A4 EDO- 57 FF 67 SS 46 5C OA FF203- 43 96 82 A6 26 91 83 23 FOB- 03 04 00 00 00 00 00 00 ADS- 05 26 21 96 BO A4 06 26 1202- 26 Fa 97 FF ?6 DO 06 AO2E0- 10 46 B2 61 02 26 OF 96 6E0- 05 06 01 02 03 04 06 00 4e0- ID 96 C7 81 72 26 DF 60 EEO- 46 56 46 56 06 FF 46 562E2- 87 at 29 26 09 OD D9 27 6E9- 01 02 00 00 00 00 00 00 AFH- 03 26 18 60 04 26 14 60 FEZ- 06 FF F7 10 00 76 FF 87:F0- 05 32 62 7E 19 66 09 FF 6F0- 04 05 06 00 02 03 04 05 A=0- 05 26 10 617 06 26 OC OC EEO- 10 01 79 FF 00 SO 724 04253- FF FF FF FF FF FF FP FF 6E9- FF FF FF FF FF FF FF FF AFB- CS OF B2 12 12 37 96 C7 EF2- DC AA 20 14 76 BO 4a 24300- OF 114 46 16 Al IC 25 ID 700- BD 2E 80 OF C4 OF 1:5 SE 500- 97 92 79 66 05 97 05 56 F00- 06 DC AC 1E 69 20 09 467.08- 22 19 A6 19 Al ID 25 IS 708- C2 30 14 9F 22 CC 00 FE Boa- CS 81 04 26 1A ED 07 26 F02- 24 04 DC 09 30 02 DC 82310- 22 11 A6 18 Al IF 25 OD 710- 23 18 BD 37 45 29 FF FF 1910- 14 60 04 26 10 40 05 26 F10- DD B2 96 DO 26 04 D6 973IB- 22 09 46 IA Al IE 25 OS 718- FF FF 9E C2 30 OC 9F 22 912- OC 60 06 26 09 67 07 63 FIB- C4 OF 31 01 26 Os 96 92720- 22 01 39 OC D4 96 AD Al 720- OF C4 OF C5 BD 7E 80 SC 820- 04 62 05 63 06 02 25 96 F20- 54 54 54 54 81 02 26 04308- 19 25 lE 22 16 96 AC AI 728- BB 27 08 23 11 10 CE 00 F77- Ct. 5! ':I. rE vs oa CS 821 F22- 06 ea cA OF at ea 26 OA-750- IS 25 16 22 OE 96 A8 Al 710- 40 OF 80 7E 30 91 02 C4 F7 - 7E :--: I= 65 Ab 07 SA SO F70- D6 B: 54 54 54 54 26 02338- 19 25 OE 22 06 96 AA At 72a- 30 OF 9C C8 24 EF BD 37 574- 4: :- - 25 80 ?7 47 39 F -,a- Ca OA EE 2F 4a 46 As 77340- IA 25 06 OD D4 26 24 20 740- 45 FD 12 80 39 9E C2 OD 94.:- ':',= Cs 0., :5 61 06 26 OE F40- AO 96 OD el 02 27 OC :9348- 04 OD D4 27 24 96 AD Al 746- C4 27 07 36 OB 6F 86 44 843- 60 07 10 :4 a6 7F A7 07 F46- DE ea Ea EC Ba 7C 7E CS750- IC 25 16 22 IC 96 AC Al 750- 24, F9 OF FE OD DB 26 03 550- 86 FF 0- 67 OC CS 96 CS F50- FE FE 00 BE 00 £7 66 07556- 10 25 10 22 10 96 AB Al 752- BD 70 E0 46 84 97 FE 39 asa- at 07 _70 17 OF 87 EC oa F58- 06 FE 6F 86 52 24 02 63760- IF 25 08 :2 OC 96 AA Ai 760- OF 09 12 OF BO OC BO CC B60- DD EZ .17 ...5 Of A4 96 A6 F60- Ba 00 24 F6 96 80 26 Oh362- 1E 24 06 A6 17 9A CD 77 768- 00 F4 DD C2 80 37 IA 90 ess- 04 BF 7° 56 OC 1:5 39 al F68- 96 AP SA 90 97 07 BE 00370- CD 39 FF FF FF FF FE FF 770- 39 DO CI 04 24 05 BD ZS B70- CE 26 OD EC OA DO 82 96 F70- 80 66 06 Ds 07 Ss OF 66778- FP Fr Fr. FF FF FF FF FF 770- 90 20 E4 53 30 92 FO AD 973- 46 Ele CO 97 46 OC C5 39 F7E- 58 25 02 67 84 44 =A F6320- 96 OF 61 OF 26 04 OD D9 760- 95 20 EC 3C 60 74 40 SA 360- OD C4 27 06 SE SS 70 22 -F30- RE 00 EF 216 0,, 6F 86 4438E1- 27 01 39 OC DO BD 27 98 733- 40 37 00 TE 48 17 IA FF ESS- 79 ea 9E C2 BD 37 20 39 FES- ZA FB 76 46 41, :5 02 03390- 96 09 97 DC BD 23 88 S6 790- 81 06 26 26 22 FB D6 Fa 974* OD FB 26 01 79 5E C2 96 Fs*- F5 46 75 .-7 7 =4 96 A779S- Fr 07 FE SD 73 E0 BD 17 792- C4 OF CI OA 27 01 39 06 878- CS 26 OF 86 01 501 27 03 Fsa- 4a 25 ,72 - =7 =4 A4 4B

=i?AO- IA 9E ea 5C C2 27 04 OA 740- FO CB 06 CI AO 26 11 OC FAO- 40 20 FA 49 84 A7 194 97 540- 25 02 ,0 == 55 48 25348- DC 26 F7 86 04 97 DC 20 7412- F? Da F9 C4 OF CI OA 26 845- FE 79 at at 27 04 at 02 FAS- 02 07 =: ,--- 50 4e 20-02380- E3 OF D9 39 FF FF FF FF 790- 06 D6 FS CB oa D7 FV 5F 6190- 26 72 6.6 04 97 67 ED OF F170- 07 FO =, .--- 46 25 02 ,7362- 96 A2 68 1? 21 31 25 02 792- 07 FEI al 01 26 11 D6 BO 832- EC 01 9A BA DA BB ED 01 FSS- EF OF F. E.. 01 VI 5') 76MO- BO 70 06 DF 53 26 05 32 720- 58 24 OC OC B1 D6 81 CI PC0- OF C5 OC C5 OF 82 7. OF FC0- 06 OD CS 28 02 OC F6 7-322- 62 OF OS 39 00 DE 26 05 7C9- 04 26 04 OF El OF 80 39 328- 82 OF B3 ED 3? 69 27 04 Fee- FF FF FF FF FF FE FE 9F300- 91 AB 26 EE 39 OD FS 27 7150- FE FF FF Fr 90 78 B6 OF 500- 86 77 97 92 OF C7 BD :A FDO- 96 OF 61 OD 26 07 PD 77306- F7 10 CE 00 AO 7E 30 31 7156- D6 IC BF 12 12 12 IA 40 509- 10 96 C7 91 82 26 F7 OF FINS- 9'3 Cb OD 32 62 7? FF FF720- 96 AB SB 03 61 21 25 02 7E0* OD 156 26 OC OF 07 96 FD 380- C7 SE C2 79 SI 07 27 04 FE0- .6 DF SI OC 26 07 BD 703E8- BO SO 71 AB 26 FC 39 FF 7E21- 21 OA 27 IC OC FO 20 OA 853- al 04 26 IE 26 02 77 873F-0- FF FF Fr FF FF FF FF FE 750- OF FO 96 157 B1 04 27 10 EFO- 190 DS EC 07 44 FA CA FE

FE F- 23 C6 OC 7Z 6Z 7? FF FFFF0- :e ea ao ea ao oo as so

:FS- FF Fr FF FF FF FF FP FF 758- OC 07 1110 0E F4 76 D7 81 SFE- ED 07 EC 05 40 EC 04 BD FF.- 77 04 70 00 30 00 70 00

5-31

programmable timerelektor may 1985

5

fitting small relays that can switch externalequipment, but often it is more convenientto fit the relay in or near the equipment tobe controlled. It is also safer in the caseof mains -operated equipment.The relay coils should be rated at 5 V andnot draw more than 80 mA: that current isthe maximum the buffer stages can passwhen all eight outputs are active simul-taneously. If that situation does not arisewith you, the current through the relaysmay be increased to about 100 mA. Therelay contacts should be shunted by aspark suppressor consisting of a100 Q/1 W resistor in series with a100 n/630 V capacitor. Remember that therelay should be connected between thepositive supply line and the relevantbuffer output!

00.0000SAT

The power supply of the timer has areserve of about 150 mA which is availablefor the relays. If more is required, an addi-tional 5 V supply must be provided. Therelays are then connected between thepositive output of that supply and outputs1...8. The 0 line of the additional supplymust be connected to the earth of thetimer circuit.Various methods of switching mains -operated equipment can be found in solidstate relay (Elektor, June 1982), amplifiedtriac drive (Elektor, July/August 1983); Lilaccontrol board (Elektor, March 1984); andphoto electronic relay (Elektor, July/August1984). These electronic relays do notrequire an additional 5 V supply, becausetheir drive current is only a fewmilliamperes.

ELEKTOR ;,R-TIMER/CALENDAR

Figure 5. The front panelof the programmabletimer. Operating instructions

Displays and LEDsHH-HH indicates time and date; centre

LED lights every second.SUN...SAT indicate day of the week.PROGRAM OUTPUT indicates the

status which the switched out-puts should have according tothe program.

REAL OUTPUT indicates the real statusof the switched outputs.

DAY OF WEEK...OFF: these eightLEDs indicate what is shown onthe display. The first five areself-explanatory. OUTPUT refersto the switched outputs. whilethe ON and OFF LEDs indicateduring programming whetherthe keyed -in data refer to an"on" or "off" function.

Keys0...9 are intended for keying in of

data, such as time and date.Keys 1...8 enable selection of

the wanted outputs during pro-gramming, and manual controlof the eight outputs during nor-mal use. When a key ispressed, the logic level of theoutput is reversed. Keys 0...6are also used during program-ming of multiple times for key-ing in the day of the week. Innormal operation, keys 0 and 9have a special function: whentime is displayed and either ofthese keys is pressed, theweekday corresponding to agiven date can be calculated(eternal calendar); more aboutthis later.

CLEAR deletes the reading of thedisplay in case an error wasmade during the keying in ofdata. When the output LEDlights during programming, andthe CLEAR key is pressed, thecurrent program is deletedcompletely.

ENTER after data (e.g., time or date)have been keyed in, pressingthe ENTER key causes the

5-32

timer to store the data in itsmemory.

NEXT enables reading a programwithout changing it. When timeis displayed, pressing NEXTonce causes the date to bedisplayed for four seconds;pressing it twice causesminutes and seconds to bedisplayed. Time display willreturn on pressing NEXT onemore time.

PRO M enables programming andchecking multiple times. Pro-grams may be read by pressingPRO M several times. or keep-ing it down. In the latter case,all eight program output LEDslight every half second,indicating that then programshave been read. Pressing thiskey once more causes a returnto the time display.

PRO S enables programming andchecking single times, i.e., pro-grams that switch on one ormore given outputs at a certaintime and data, and switch offagain at a different time anddate. The key function in allother respects as the PRO Mkey.

LAST enables going back one ormore programs when the timeris in the programming mode.

TimeEntry of time After the mains has been switched

on. the timer is on 0.00 and YEAR Key in the year. followed by pressing

ENTER. The display will show 1 01 and DAY

and MONTH light. Key in the day and month and press

ENTER. The display will show 0 00 and TIME

lights. Key in the correct time (hours and

minutes) and press ENTER: the timerthen commences and the weekdayis indicated.

Correcting of time Keeping PRO M (or PRO S) pressed,

also press PRO S (or PRO M).Pressing NEXT will then cause alltime data to be displayed.

If anything needs correcting, pressCLEAR, key in the new data, andpress ENTER.

During correcting, time continues torun. Only after a new time has beenkeyed in, followed by ENTER, willthe clock run from the new time.

Eternal calendar Press 0 or 9, when the current year

will be displayed, and YEAR willlight.

Key in the required year, followed by

ENTER; then day and month, againfollowed by ENTER. The SUN...SATLEDs will indicate which day cor-responds to that date.

Press NEXT, when normal time willbe displayed again.

Miscellaneous Press NEXT once. when the date will

be displayed for four seconds. Press NEXT twice. when the minutes

and seconds will be displayed; thesewill remain displayed until NEXT ispressed once more.

Keys 1...8 enable the manualswitching of the outputs; the outputstatus will be indicated by the REALOUTPUT LEDs.

ProgrammingSingle times Press PRO S, when OUTPUT will

light. Select the wanted output with keys

1...8, when the correspondingPROGRAM OUTPUT LEDs will light;when the key is pressed again, theLED will go out.

Press ENTER. when ON, DAY, andMONTH will light to indicate that theswitching on date should be keyedin.

Key in the date and month, followedby ENTER, when ON and TIME willlight to indicate that the switchingon time should be keyed in. Key inthat time, followed by ENTER, whenOFF, DAY, and MONTH will light toindicate that the switching off dateshould be keyed in.

Key in the date and month, followedby ENTER, when ON and TIME willlight to indicate that the switchingoff time should be keyed in.

Key in the switching off time andpress ENTER. when the relevantPROGRAM OUTPUT LEDs will lightagain.

If required, check all keyed -in datawith the NEXT key. Wherenecessary, corrections may beentered (new data, followed byENTER).

If more switching programs have tobe entered, press the PRO S key andproceed as above. Otherwise, pressPRO S again, when normal operationwill resume.

Multiple times Press PRO M, when OUTPUT will

light. Select the wanted output with keys

1...8, and press ENTER, whenMONTH will light.

Key in the switching on month, fol-lowed by ENTER. More months maynow be keyed in, if required, eachtime followed by ENTER.

After the last month has been keyedin, repeat all keyed -in months withthe NEXT key. After the last month

programmable timerelektor may 1985

PRO M - progr.multiple time

PRO S = progr. singletime

5-33

programmable timerelektor may 1985

has been displayed, the timer goesto DAY.

Key in one or more dates asrequired, each date to be followedby ENTER. Check with the NEXTkey; after the last date, DAY OFWEEK will light.

Key in one or more days of weekand then ENTER (in this case NOTafter each day). This allows, forinstance, that only when the 15th and23rd of February and March fall on aSunday or Saturday, output 1switches on from 9 a.m. till 11.30a.m. If this facility is not required,just press ENTER. This alsoapplies to months and dates: if nomonth is keyed in, the switching onand off times will apply to the stateddates in every month. It is also poss-ible to program only weekdays (i.e.,no months or dates); the cycle willthen repeat itself every week.

After DAY OF WEEK, ON and TIMEwill light to indicate that theswitching on time should be keyedin.

When that is done, OFF and TIMEwill light to indicate that theswitching off time should be keyedin.

When the switching off time hasbeen keyed in, followed by ENTER,when the relevant PROGRAM OUT-PUT LEDs will light again.

If more switching programs have tobe entered, press the PRO M keyand proceed as above. Otherwise,press PRO M again, when normaloperation will resume.

Checking and deletingprogramsIf, at a later date, it is required to add aProgram, press the PRO M or PRO Skey several times until none of thePROGRAM OUTPUT LEDs lights toindicate that the position reached isfree. If these keys are kept down, thesearch is much faster.The PRO M and PRO S keys enable aforward run through the programs; theLAST key permits a backward search.In the programming mode, checking ofa program is always possible with theNEXT key; corrections may be madewith the CLEAR and ENTER keys.A complete program may be deletedby locating it with the PRO M or PRO Skey and pressing CLEAR. All followingprograms will then automatically shiftup one place.Remember that the actual status of theoutputs is indicated by the REAL OUT-PUT LEDs!Remember that when the lockingswitch is open, the programming func-tions (and setting the time) aredisabled!

5-34

A computer without an I/O (input/output) facility may be comparedwith a telephone without a receiver: it probably works all right, butyou cannot tell. In the same way, a computer can only be usedproperly when it can be connected to external equipment ornetworks. It is for that reason that we have designed an I/O interfacefor the Commodore 64, but which may also be used with most otherpersonal micros. It permits the computer to be connected todigital/analog converters, digitizers, parallel and serial interfaces,sound generators, and many more.

universal I/O buselektor may 1985

universal I/O busFor some obscure reason, connectingexternal equipment to a computer oftencauses problems. And yet, the usefulnessof a micro depends primarily on thefacility for using peripheral equipment. Inmany cases, the I/O facility is severelyrestricted and this acts as a brake to theinventiveness of many computer users.This void may be filled with the proposeduniversal I/O bus. The word 'universal' isused deliberately, because the bus can beconnected to virtually any computersystem. It offers four independent I/Oports to which a number of external unitsor networks may be connected.

Design considerationsA computer system is nothing but an arrayof interfacing units with at the centre themicroprocessor, the memory, bistables.and ports. To enable this core to workwith the peripheral equipment: compilers,assemblers, operating systems, printers,monitors, and so on, it needs a means ofcommunicating with these units. This datatransfer may take place via specific ICs,such as PIAs (peripheral interfaceadapter), VIAs (versatile interface adapter),or ACIAs (asynchronous communicationsinterface adapter). Such circuits are nor-mally used for the keyboard connection,the printer connection, or the serialinterface.There is a more direct way: via thedatabus of the system. This form ofinput/output can be achieved by I/O map-ping or memory mapping, depending onhow the memory is arranged (seefigure 1).In I/O mapping, the memory locationsallocated to the input/output ports areseparated from the memory proper bycontrol lines, for instance, IOR (I/O read).or IOW (I/O write).In memory mapping, the I/O allocationsare contained within the memory itself,which is, therefore, divided into memoryand I/O locations. Each I/O location is, inessence, an I/O port. The data bus is splitover the various port connections byaddress decoders.The proposed design uses memory map-

ping, as this enables it being used with agreater variety of computers. None theless, it can also use I/O mapping, as willbe seen later in the article.

Block schematicThe proposed I/O bus is shownschematically in figure 2. The address bus,data bus, and control bus emanate fromthe computer. The highest address lines,A4...A15, are taken to the I/O rangedecoder, which determines the range ofthe I/O ports. A memory range of sixteensequential addresses may be selected forthe I/O with memory range switches. Inthis range, the data lines are connected tothe ports (slots 1...4) via the buffer. Therange is divided into four groups ofaddresses, each of which has fourlocations: the real I/O ports. Address linesAl and AO are connected to the slots toenable the individual selection of the fouraddresses.The location of the I/O range in thememory is arbitrary. If the I/O rangeswitches are set to a value of 400 hexa-decimal (the first three nibbles of theI/O addresses), slot 1 will extend from4000 to 4003 incl.; slot 2 from 4004 to 4007

1

-4-0

memory

range

I/O mapped I/O

memory

I/Orange

memory mapped I/O

1119358-1

for theCommodore 64and many othermicros

Figure 1. This illustratesthe difference between1.0 mapping and memorymapping.

5-35

universal 110 buselektor may 1985 2

2. Schematicrepresentation of theuniversal I/O bus.

D7

.0

5

D

data bus

D7

1---1 control bus

buffer

AO

A15I A15

address bus

A4

A15

I/0 -range

decoder

MSS LSB

I/O address

4

slotdecoder

0

ttttHitt

slot 1

slot 2

slot 3

slot 4

powersupply

85058-2

incl.; slot 3 from 4008 to 400B incl.; andslot 4 from 400C to 400F incl. It is clearthat, to prevent double addressing, theselocations must not be occupied by thememory proper.There is also a control bus with aread/write output for input and outputrespectively, a common reset and inter-rupt line, and a 02 signal for a possiblesynchronization facility.An external supply (+5 V; ±12 V) may beconnected to augment the existing powersupply in the computer.

Circuit descriptionThe circuit diagram of figure 3 is remi-niscent of the block schematic in figure 2.The I/O range decoder is formed by IC3and IC4. These cascaded 8 -bit devicescompare address lines A4...A15 with thecode set by DIL switches Si and S2. Whenthese lines match the code, the P=Q out-put of IC4 becomes active, and the conse-quent output signal is applied to theenable input of both IC1 and IC5 via wirelink b. The data direction of buffer IC1 isreversed by the R/W (read/write) signal.Dual 2 -to -4 line decoder IC5 decodes thefour slot select signals, SS1...SS4, from thesixteen I/O locations. This means thateach slot has four sequential addresses.The slot select signals can finally be used

as enable signals (active = logic low) forICs, buffers, and the like.Each slot also contains the eight datalines, the R/W, the NRST (negative reset).the IRQ (interrupt request), 02, and thepower lines (+5 V; ±12 V; earth). Addresslines Al and AO represent four addresslocations in a slot. These are often usedfor register select inputs of VIAs andsimilar devices. The synchronizationclock, 02, is also more often used withperipheral ICs. There is a facility on thebus board to synchronize the data bussignals with 02 (wire link f) to obviate so-called bus conflicts.Finally, the system bus has connectionsBUS SEL (bus select) and BUS ACK (busacknowledge). The bus select input maybe used for external actuation of the I/Obus (so-called half -memory mapped),while the BUS ACK output indicates whenthe bus is actuated. This signal may befed back to certain computers to switchoff the memory.Power for the circuit is normally drawnfrom the +5 V supply in the computer. Ifthat supply is thereby stretched, or ifseveral levels of voltage are required, theauxiliary supply given in figure 4 may beused. This provides +5 V, ±12 V via three1 A regulators. When the auxiliary supplyis used, the +5 V from the computer mustnot be used, but the earth or power returnlines must, of course, be interconnected.

5-36

ConstructionThe bus is most conveniently built on thepcb illustrated in figure 5. The peripheralpcbs should be inserted into the slot con-nectors at right angles to the board offigure 5. We have not indicated the con-nections to the computer, because thereis such a multitude of differencesbetween the various makes that thisbecomes totally impracticable.When the auxiliary power supply is used,the +5 V connection must not be used.The DIL switches are mounted so that,

viewed from the system bus, the MSB(most significant bit) is at the left, and theLSB (least significant bit) is at the right.This facilitates the locating of the I/Orange.

OperationAfter the bus has been built andthoroughly checked, it is connected tothe computer. As there are so many dif-ferences between various makes of com-puter, it is not possible to give connection

3

.5V

r1

01

DO 0-IDI 0-021 0-031 0-13.4

OS1 0- NMI 0-071

NRST 0IRO

R/.2 002 0

40AlA2A3

44AS

AS

A7

AS

49410All412413

415

BUSSE!.

BUS ACK

O

0

Ve

19

.4:1104:11 :

IC1

74 LS 245

0 R

3

5

67

9

N

9

T 3

2 3

universal I/O buselektor may 1985

Figure 3. Circuit diagramof the universal I/O bus.

N1 ... N4 = 106 = 74LS02

07

17

A 2

415

12

IC2

74 LS 244

20 IG

314

9

5

16

'p2

5V

1-IQ

Rini LI,

a

COU2

030105

Q6

07 P7P

190

90 1.

PI aP2 13

15

17

IC3

74LS

688

10

[0 0 0 0 0 0SI

IC4

P3

52

11

B

13

616 74 15

18 688LS

12P63 07 P7 1.0

190

R91 I I I I/112

1.1

OV o

L_J

Gab

Or

5V

14

15f-0

8 O O 2 O O 0 0 7

551 1- 1 2 3

SS2

> > >V V :-:

0 0O

4 5 6 7 B 9 10 11 12 6 17 18 19 21

O

O 0 09

A 9D._12

IC5;F,1

G 74Y2013_LS y9 DA

139

O O 0 0 0

SS3

3 4 5 6 7 0,11 12 14115 16 1718 1920

SSA

5V

0 0 0 6 o6 16

621

0 0 0

RI -.R12. 12,47 kCl = 6:100n

C5 Ca C2IC3 IC4 = IC5 IC6 ...,

7; T. (?.

O

O

Io

Io

85058 -3

5-37

universal I 0 buse!eiitor may 1985

Figure 4. Circuit diagramof the optional auxiliarypower supply.

Figure 5. The printed cir-cuit board of the I 0 bus.

4r

D1 ... D4 =1N4001

89058

IC37805 e 5 v

Tant.

=i1p 16V

C5 Taro.=1

6I1p 16V0C6 rant.

instructions for all micros in detail.In the Commodore 64. the expansion con-nector is used: the pin designations ofthis are given in figure 6. Pins DO... D7.

AO... A3. IRQ, tp2, GND. and possibly *5.are connected to the corresponding ter-minals on the bus board. RESET is con-nected to NRST, and I/O select output1/01 is connected to the BUS SEL input.Output I/01 represents I/O address rangeDE00...DEFF. so that the slots areoccupied as follows: slot 1 - DE00...DE03:II slot 2 -DE04...DE07; slot 3 -DE08...DEOB:II slot 4 - DEOC...DEOF.Finally. fit wire links a. d, and f on the busboard, and then you can peek and poketo your heart's content.As far as other makes of computer areconcerned, first set the functions of thebus with wire links a...g. If the computercontains a full data. address. and controlbus. the bus decoding is effected by IC3and IC4. This means that wire links b andd should be fitted. After that. reading andwriting can take place in the selectedaddresses. Switches S1 and S2 set thebeginning of the I/O ranae. If that is. forinstance. 4000,., the switches are set.from left to right: 010 000 000 000 (0 =switch closed; 1 = switch open).If you select a constant enable of tl'te bus.for instance, with control by a PIA. fit wirelinks c and e. This precludes addressdecoding in IC3 and IC4.If, instead of a complete system bus. onlyuser ports are available. the bus cart be

5

:Re:impe/Sfm(-1.1.11.0110.a.11.1,111M 1.111MIIM1101--;a0im

YITAA;;Ei.."%,14=

5-38

connected via a round about way. SignalsBUS SEL, AO, AI, A2, and A3 are thentaken to a separate user port and can thenbe controlled by a (somewhat more com-plex) poke. In this case, fit wire links aand d. This method may also be employedin case of control by a PIA. Here again,the decoder function of IC3 and IC4 isdisabled.The BUS SEL input can also be usedwhere a decoded address is alreadyavailable on the bus, for instance. withexisting applications. Addresses A0...A3are as normal put onto the address bus,and BUS SEL onto the select output of thatdecoded address range (which is active atlow logic levels). In this case, fit wire linksa and d.The synchronization clock, 02, is, apartfrom at the ports, also present in the buscircuit itself, and cart, therefore, be usedto synchronize the data bus. This is notalways necessary (for instance, where thesystem bus of the computer is alreadysynchronized), but it does not do anyharm. If the facility is used, fit wire link g.The indications to the system bus connec-tions only apply to 6500 and 6800 systems.Signals R/W and (4)2 do not exist in Z80systems. Instead of 02, the IOREQ signalcan then be used, while in place of R/Wthe WR signal may be employed.As you can see, interconnecting the busand your specific computer requires some

6

CND 1

.5 2

.5 3

IRO 4

CRATi

DOT CLOCK

101 7

GAMEEXR01.1 9

102 10

RCM L 11

BA 12DMA 13

07 1406 1505 1604 17

D3 1502 1901 20DO 21

GRD 22

5

6

A GN0 ROMHC RESETD NMIE :2F A15

H AldJ AI3K Al2L AllIA AIDN A9

P ASR Al

A6T A5

U A4A3

W 52X AlY AO

Z GND

85058-6

C

thought, but, with the guide lines given, itshould be fairly straightforward.As far as the frequency of the systemclock is concerned, the bus circuitpresents no problems. If. for instance, themicro operates at 2 MHz. the peripheralunits should obviously be able to copewith that.

Figure 6. Pin out of theexpansion port of theCommodore 64.

Parts list

Resistors:

R1...R12 = 47kR13 = 10 kR14 = 4k7

Capacitors:Cl _ _ .C6 = 100 n

Semiconductors:

Ti = BC 5471C1 = 74LS245IC2 = 74LS244IC3,1C4 = 74LS688IC5 - 74LS139106 = 74LS02

Miscellaneous:

Si = DIL switch, 8 -pole,single throw

S2 = DIL switch, 4 -pole,single throw

4 connectors, 21 -way, toDIN 41617

single row block with fourscrew terminals for0.1 inch matrix

dual row terminal strip for0.1 inch matrix, eachrow of 7 pins

three shorting links to fitterminal strip

pcb 85058

5 39

an IBM compatible micro

CAD = computer -aideddesign

CAM = computer -aidedmanufacture

A great many people would loveto own a really first classpersonal computer, but aredefeated by the cost of such amachine. It is for those peoplethat we have designed a PC thatis compatible with what iscurrently probably the best PCaround. We had planned topublish the project this month,but, unfortunately, owing to lacka space this was not to be. Itwill, however, definitely appear inthese pages next month. Ourapologies to all those keenreaders who would have liked tomake an immediate start!

In principle, it is possible to build anycomputer yourself, presupposing, ofcourse, that you can obtain all thenecessary parts. This is true even for anIBM PC2 compatible, which will give youan entree to the 16 -bit world and a mass ofefficient software. Note well that this soft-ware is immediately usable: it does nothave to be modified in any sense.There are not all that many IBM com-patible machines, and most of those areJapanese. It is an open question why sofew home-made IBM compatible machinesexist. Is it because most people think it istoo difficult? We have tried to find theanswer to that question, and can now saythat it is not: the prototype is working verysatisfactorily in our laboratories and con-tinues to do so.There is not much to say about theIBM PC2 that is not already well known.This machine has set yardsticks by whichall other home computers are measured.Together with its compatible brothers andsisters, it has gained almost seventy-fiveper cent of the world's home computermarkets. Part of its appeal, of course, thetremendous amount of software that doesnot consist for 80...90 per cent of games.The software ranges from a simple editor(at around £30...£40) to a completeCAD/CAM system at anything from £10 000upwards, and contains a farm adminis-tration program as well as a blendoptimization program for the timber, steel,and glass industry.We have found that building the compat-ible prototype does not present anexperienced electronics hobbyist withinsurmountable problems. That does notmean to say that it is easy! We also had noproblems in obtaining the required parts.There still remains the question why sofew compatible machines exist. As wehave seen, it is not the degree of diffi-

culty, nor is it that there is no softwareavailable. It cannot be the technologyused by IBM: this is pretty well current.We -have a feeling that the cause lies tosome extent in the typical buyer/user ofthe IBM PC2 as contrasted with the Appleuser. The former are largely small andmedium businesses as well as pro-fessional people: doctors; lawyers;managers; company directors, who in themain would not dream of building theirown computer, whereas the latter includesmany electronics hobbyists.Another factor is that. in the main, thetechnical press has hardly touched uponthe subject; at least not as far as we havebeen able to find in any of the world'stechnical periodicals. The only 16 -bit DIYcomputers published are not, in the truesense of the word. IBM compatible. Mostof these are 68000 machines, the softwareof which is either wanting or veryexpensive.Where the software is offered as compat-ible, it has often been adapted so badlythat the home constructor is still facedwith figuring out his own modificationsand improvements. At the prices con-sidered here, some £2000...£3000, that isnot going to attract a great many people.No, it is far better to build your own com-patible and leave those problems toothers.For our prototype we have used theMegaboard (part) construction kit, whichis produced by DTC of Dallas, Texas, USA,and which is available from a number ofspecialist retailers. This kit contains themother board (complete with componentlayout foil and solder resist), the BootEPROM with MEGA BIOS, the memorymapping PROM, and extensive documen-tation (c. 90 pages) giving full instructionsfor the construction and operation, andcontaining all necessary circuit diagrams,timing diagrams, and so on. We advise allthose interested to work with this or asimilar kit, because then you will not haveany problems with the PROM and EPROM;you can, of course, buy those bythemselves, but you then have to programthem, and that's the crux of the matter.The assembly instructions supplied withthe Megaboard kit are a great help withthe completion of the mother board. Toexplain: the IBM PC2 is a modular con-structed computer, which means that themother board contains apart from the pro-cessor. RAM banks, and so on, also six (inthe IBM PC2), but eight in the case of theMegaboard, positions for extension cards.Two of these at least are needed for thevideo card and the floppy controller card.And then there are: power supply; drives;keyboard;... All these will, of course, belooked at in detail in the constructionarticle which will be published in ourJune issue. 14

5-40

elektor may 1985

the first cuckooin spring...(April 1985. page 4-45)The operational amplifier inthe IC1 position should be atype TL084 and not 1M324 asstated.

5-41

elektor may 1985

How to make your own PCBsYou require an aerosol of 'ISOdraft'transparentizer (distributors for the UK:Cannon & Wrin. 68 High St.. Chislehurst,Kent. 01 467 0935, who will supply thename and address of your local stockist onrequest), a mercury vapour lamp. sodiumhydroxide (caustic soda). ferric chloride,positive photo -sensitive board material(which can be either bought or homemade by applying a film of photo -copyinglacquer to normal board material). Wet the photo -sensitive (track) side of

the board thoroughly with thetransparant spray. Lay the layout cut from the relevant

autornonitor

DANCER! Ultra -violet light is harmful to your eyes, so when working witha mercury vapour Lamp. wear some form of effective eye protection.

page of this magazine with its printedside onto the wet board. Remove any airbubbles by carefully 'ironing' the cut-outwith some tissue paper. The whole can now be exposed to ultra-

violet light. ' The exposure time is dependent upon

the ultra -violet lamp used, the distanceof the lamp from the board, and the photo-sensitive board. If you use a 300 watt UVlamp at a distance of about 40 cm from theboard and a sheet of perspex. an exposuretime of 4...8 minutes should normally besufficient. After exposure, remove the layout sheet

(which can be used again), and rinse

programmable timer 1

the board thoroughly under running water. After the photo -sensitive film has been

developed in a sodium hydroxide solu-tion (about 9 grammes of caustic soda toone litre of water) for no more than21/2...3 reins at 20°C. the board can beetched in ferric chloride (500 grammes ofFeC13 to one litre of water). Then rinse theboard (and your hands!) thoroughly underrunning water. It is advisable to wear rub-ber or plastic gloves when working withcaustic soda or ferric chloride solutions. Remove the photo -sensitive film from

the copper tracts with wire wool anddrill the holes.

5-47

elektor may 1985

PC board pages

programmable timer 2

cli4g,)

=:zam rtk......................

Mr des MI,0ce Sem

V-11

eltimSW-N'k fir'-G\NZBEB/--NOM.JEMff0 0 0 all 0 0 0ciirF En :W" co a am looAr a:a VS r lra

am ea um anJul Nor jpeio

-VP.028

01:243/pcs

universal I/O bus

OOOOO0=,

130008

.24

r

glow plug modulator

5-43

PC board pages

- ,. ".-..--=

5-44

04

S.

Modellers using glow plugengines are often plagued bystarting problems. These arecaused by the glow plug notbeing able to cope with thesudden inrush of the cold fuelmixture that extinguishes thefilament so that ignition cannottake place. The circuit proposedhere ensures that the filamentcontinues to glow under allcircumstances so that any enginecontrolled by it becomes a readystarter!

glowplugmodulator

C

The filament, a spiral -shaped piece ofthin, durable metal wire, acts as the spark-ing plug for model diesel engines. Whena current flows through it, the wire beginsto glow, which ignites the fuel mixture.Once the engine runs, the ensuing heat inthe cylinder is sufficient to keep the fila-ment glowing, and the current cantherefore be switched off.On the face of it, this seems to be anexcellent system, but in practice, the situ-ation is somewhat different, because glowplug engines use volatile fuels. As soon asthe cold fuel mixture enters the compres-sion chamber, its evaporation causes sucha lowering of temperature that the filamentno longer glows. Starting then becomesvery difficult, if not impossible, which ismade even worse by the ensuing floodingof the engine. To cure this ailment, ameans has to be devised which ensuresthat the filament continues to glow in spiteof the cooling in the compressionchamber.

Control systemSomething is needed that enables thecontinuous monitoring of the filament tem-perature. As it is rather difficult to fit atemperature sensor in the compressionchamber, another means has to be found.Fortunately, most glow plugs, like thefilaments of incandescent lamps, have apositive temperature coefficient. This

means that the higher the current flowingthrough it, the brighter it will glow, andthe higher its resistance. That resistanceis, therefore, an excellent indicator of thetemperature. Instead of the resistance, itwould, of course, also be possible tomeasure the voltage drop across the fila-ment at a given constant current. Thetemperature -dependent voltage couldthen serve as the basis of a control

1

glow plug modulatorelektor may 1985

starting aid formodel engines

Figure 1. Schematicrepresentation of thepulsewidth modulator.

ImportantThere are two types of glowplug. One has a resistancethat is virtually independentof temperature; the modu-lator described here cannotbe used with this type ofplug. Therefore, checkwhich type your engine usesbefore tackling this project.

5-45

glow plug modulatorelektor may 1985

Figure 2. Circuit diagramof the glow plugmodulator.

system. The diagram in figure 1 showshow this can be achieved.The filament, Rg, is fed by two currentsources, one - IK - constant, and theother - Ivar - variable. Source IK causesa current of some 1 A through the glowplug. The resulting voltage drop acrossRg is applied to the non -inverting input ofcomparator K via an S&H (sample andhold) stage. The voltage is compared in Kwith the output of a triangular -pulse gen-erator. The output of the comparator will,therefore, consist of a pulse train whosefrequency is identical to that of thetriangular signal. The width of thesepulses is determined by the temperature -dependent voltage derived from the glowplug. The pulse signal controls sourceIvan which provides the filament withadditional current when the controlvoltage (i.e., temperature) is low. Bysuperimposing the output of the triangularpulse generator onto a direct voltage thatcan be set with P, the temperature of theglow plug can be set very accurately. It isclear from the foregoing that the systemdepends on pulse -width modulation.A reliable control voltage is dependent onthe same current being monitored at alltimes. In the present circuit this is the cur-

rent provided by IK; that from I mustremain irrelevant: these conditions are metby the S&H stage. During current pulsesfrom Ivan this stage acts as a reversebiased diode, while it retains the pre-viously measured voltage level for aninstant.

Circuit descriptionA constant -current source is provided byT3 in figure 2. Light -emitting diode D3serves as a voltage reference source andit must, therefore, be a red type. It alsoindicates whether the filament is correct:if this were defect, no current would flow,and the LED would not light. Themeasured voltage is first applied to thesample -and -hold stage formed by R8, D2,and C6. The capacitor functions as amemory, while the diode is reverse biasedby the current fluctuations caused by Imo,i.e., transistors T1 and T2. Diode D2 is onlyforward biased during the intervalsbetween the fluctuations, and then con-ducts via R8. This raises the voltage acrossC6 by 0.6 V, but this increase is negatedby diode Dl. The voltage is then appliedto the non -inverting input of comparatorIC4.

2IC1

7808

RI

700n TOOn

RI C4

IC2 = LF 356, 741IC3 = LF 356, 741IC4 = CA 3140

R2

47n

7

IC3180n

CS6 3

ClO

O

100P16V

115 R14

reel

BD 240 BD 679

BCER15

EC B

IV

R13

T2,

C0

glow plug "-

P1

R7

D1.02= 1N4001

5 ie.

IP 2955R12

T

1C4

TIP 2955

O

RIO

B C E

BD 679

85053-2

5-46

3

17) 85°513f:

107°-ft crit q

li_Ni-ciemmtceT, I up

The triangular -pulse generator is con-structed from two standard opamps. IC2and IC3. Capacitor C5 removes the DCcomponent from the output signal of thegenerator, which is subsequently superim-posed on an accurate DC offset voltage of400...800 mV before being applied to theinverting input of IC4. The offset voltage isderived from adjustable voltage dividerR6/PI/R7. The operating point - and con-sequently the temperature of the filament- can, therefore, be set very accuratelywith Pl.The output of the comparator drives T1and T2, of which the latter is capable ofproviding currents up to 8 A to the glowplug.To prevent inaccuracies in the pulse -widthcontrol system, the power supply for thecomparator and the triangular -pulse gen-erator is regulated by ICI. The supplyvoltage may be drawn from a 12 V battery;the circuit performs correctly down to10.5 V.

ConstructionThe circuit is most conveniently con-structed on the pcb shown in figure 3.Only two points need watching.The first is that transistors T2 and T3 havea rather high dissipation and must,therefore, be adequately cooled. They arebest mounted together on one heat sink(do not forget the insulating washers!). Theheat sink should be rated at about10°C/W.The second point concerns various con-nections. Because the current through thefilament is of the order of severalamperes, it is advisable to use pretty thick

wire for the connections between the bat-tery and the pcb and between the pcband the glow plug. The cross-sectionalarea of the conductor should definitelynot be less than 2.5 mm2.

OperationThe circuit need not be calibrated. If youhave used the pcb and the componentsrecommended in the parts list, there is noreason for the modulator not to work firsttime. If you have any difficulties, checkthat the triangular voltage is present at thejunction of IC3 and C5: the level shouldbe around 200 mV, and the frequencysome 1200 Hz. At the junction of C5 withPI and R6, in addition to the triangularvoltage, there should be a direct voltageadjustable between 400 and 800 mV withP1.The correct setting of PI for various typesof glow plugs can only be ascertainedexperimentally. To do this, first set PI tominimum resistance, and then connect theglow plug to terminals X and Y, beforeconnecting the supply voltage. If D3 doesnot light, the plug is defect. If the LEDdoes light, turn PI gradually until the fila-ment glows bright orange -red. Only actualuse will indicate whether PI needs a smallcorrective adjustment.There are quite a few types of glow plugon the market, and their varyingcharacteristics will require a different set-ting of PI for each. Therefore, if youreplace a plug, it is necessary to set PIfrom scratch as described. 14

glow plug modulatorelektor may 1985

Figure 3. The printed cir-cuit board of themodulator.

Parts list

Resistors:

R1,R2,R3,R8,R9,R11 = 10 kR4 = 330 kR5 = 120 kR6 = 82 kR7 = 4k7R10 = 2k2R12 = 33R13 = 0,1 4/5 WR14 = 1 415 WR15 = 470R16 = 407/5 W

Capacitors:Cl = 100 p/16 VC2,C3 = 100 nC4 = 47 nC5 = 180 nC6 = 1 0116 V

Semiconductors:T1 = BD 679T2 = TIP 2955T3 = BD 240D1,D2 = 1N4001D3 = LED red Isee text)1C1 = 7808IC2,1C3 = LF 356, 741IC4 = CA 3140

Miscellaneous:

P1 = 5 k, presetHeat sink for T2 and T3:rating 10°C/W

PCB 85053 1105 x 50 mm)

5-47

Communication with the outside world is vital for a computer, butmost information from that outside world arrives in analogue, that is,continuously varying, form rather than as a series of binary digits,bits, which are the computer's staple diet. The continuously varyingsignals can be converted into bits by the digitizer presented here. Thepcb on which the digitizer is housed fits nicely onto the versatileinput output bus featured elsewhere in this issue. It comprises asingle analogue/digital converter IC, the input of which is connectedvia software to one of the eight analogue input terminals on the pcb.Operation is simple and effected by BASIC with a single peek andpoke command.

digitizerthe outside link

The layout of the digitizer is fairly simple;yet, its performance is excellent. ThePrinted circuit board (pcb) has eight inputterminals, to each of which an analoguesignal may be applied. A poke commandin BASIC enables the selection of one ofthe eight input pins which is then con-nected to the input of the converter IC.The same command serves to start theanalogue -to -digital conversion process.Afterwards, the converted bits may beextracted with a peek command for pro-cessing in the computer.

The converter ICNational Semiconductor's ADC0804 is aneight -bit analogue/digital converter thatoperates by the successive approximationmethod. It has been designed specially

for use with microprocessors, so that itcontains eight data outputs that can beswitched to a high -impedance state. Theeight outputs tell us at once that the resol-ution of the converter is 28 = 256 steps.In the successive approximation method,the input voltage is compared, in discretesteps, with a reference voltage that inbinary divided steps approaches the inputvoltage more and more accurately. The ICtherefore uses a ladder network ofR -2R resistors and a reference voltage,Vw. First, half the reference voltage iscompared with the input voltage, Vm. IfV. < '/z Vii, the highest -numbered outputgoes logic low, and the reference voltageis reduced to 1/4 lizep which is again com-pared with Vin. If V;i., >'/z the highest -numbered output goes logic high, and thereference voltage is increased to 3/4 V.!.Depending on the result, the referencevoltage is reduced or increased by lisKeiat the next step; by 1,161Tref the followingstep; and so on, until all eight outputshave a logic value (1 or 0).The block schematic of the ADC0804 isshown in figure 1. The voltage provided by

5.48 .

the ladder network is set with on -chipanalogue switches. The most significantbit (MSB) is tested first. and after eightcomparisons (sixty-four clock pulses), theeight outputs of the ladder have a binarycode that represents the value of the inputsignal (1111 1111 = full scale). That code istransferred to the output latches, and atthe same time an interrupt signal is givenvia the INTR bistable.There are two inputs via which the con-verter may be enabled: WR and CS, butfirst, the IC has to be selected by a logiclow at CS. When the WR input goes fromlogic high to low, the on -chip SAR back-ing stores are reset. As long as CS andWR remain logic low, the converterremains in the reset state. The conversionprocess does not commence until 1...8clock periods after at least one of theseinputs has gone logic high.The reset state (both CS and WR logiclow) implies the following: the startingbistable, F/F, is set which causes the reset-ting of the interrupt bistable; the Q outputof D -type bistable F/Fl goes high: thislogic level is applied to the input of the8 -bit shift register after one clock pulse,and also to the input of AND gate Gl. ThisAND gate combines the "1" with theclock signal into a reset signal for thestarting bistable. When after that a "1" isapplied to one of the inputs CS and WR,the starting bistable is reset, whereuponthe shift register accepts the "1" from F/Fland the conversion process commences.

After the "1" has been clocked throughthe shift register, it appears at the Q out-put of the register to indicate that the con-version can be terminated. This highsignal also ensures via AND gate G2 thatthe digital levels are entered into the out-put latches. At the next clock pulse, the"1" is written into D -type bistable F/F2,which causes the setting of interruptbistable INTR F/F, whereupon the INTRoutput goes logic low via an inverter.For reading the data. the combinationCS/RD ensures that the interrupt bistableis reset, and that the data appear at theoutputs of the output latches. These out-puts are normally high impedance.

Circuit descriptionThe heart of the digitizer is, of course, theanalogue/digital converter, ICI - seefigure 2. Resistor R4 and capacitor C2 arethe frequency determining componentsfor the on -chip clock. The WR input,pin 3, is connected direct to the R/W ter-minal on the I/O bus. The CS input, pin 1.is fed with a combination of 02 and SS(slot select) via gates N2 and N3. The RDsignal for pin 2 is derived from the R/Wsignal via inverter Nl.The input of IC1, pin 6, is fed from theoutput. pin 3) of eight -channel multiplexerIC3. The inputs of this IC. pins 1...8,accept analogue signals over a maximumrange of 0...5 V. Which of the signals isconnected to ICI is determined by four -bit latch IC2. This latch is controlled via

1

ix&

vcc CVRIf$0

VRES10

SE

OTC

SCOUT)

LADDERRAID

DECODER

I START

-1' RESIT L41FT RE SISTER1- SUIT LID RESIT STATE

IANTFACITECT41171211All11701C1110%111

OciuT

701111551111wr CIRCUITSIv AMY

4

7

vet

vits 10

tS ADTE potRaoz

SARLATCH

.11071

A

IR STATE05 MT LATCRES

CIA

i-liTpin R

RES1ST1A

2[11

D

Kul 1 1 1 1 1 1 1"11 12 IT It IS II I/ IS

D10ETAL 017771171

TR. STATE. COSTROL-1- OUTPUT CAUSE

EDIT

SET

01:1V

L-Is 11

START COAVERVOli

IF 01051

[010 'I

10

digitizerelektor may 1985

A bistable tmultivibrator) isalso known as a half -shiftregister or by its Americanname flip-flop.

Figure 1. Internal connec-tion diagram of theanalogue -to -digital con-verter IC.

Note 1: CS shorn twice for clarity.Nola 2: SAR Successive Approximation Register.

85063-1

5-49

digitizerelektor may 1985

Figure 2. Circuit diagramof the digitizer.

data lines Da ..D2 and it receives theclock pulses from the 02 terminal viainverter N4.The reference voltage is supplied byzener DI and JFET opamp IC5. TheLM 336 reference zener may be replacedby a normal 1.8...2.2 V zener whereoptimum performance is not so important.

ConstructionIf the digitizer is built on the printed cir-cuit board shown in figure 3. no difficult-ies are likely to arise.

Using the digitizerIt is important to read the article universalI/O bus elsewhere in this issue beforetaking the digitizer into use. The digitizeris inserted into one of the slots on the I/Obus. Depending on the chosen slot andthe setting of the address decodingswitches, the digitizer is then located in agiven range of four addresses.First, with the aid of a digital voltmeter, setthe voltage at the Vet/2 terminal to exactly2.5 V with preset Pl. The input voltagerange then covers 0...5 V. Where a differ-ent range is required, the referencevoltage must be altered accordingly. The

zener voltage must always be slightlysmaller than half the wanted range. If itthen proves impossible to adjust P1 forV,f/2, increase the value of R2.With a POKE command, write a numberbetween 0 and 7 into one of the fouraddresses of the relevant slot; this selectsone of the eight inputs 0...7 and startsthe conversion process. Subsequently,with a PEEK command, the bits can beextracted from one of the four addresses.An additional waiting loop during the con-version is not necessary, because BASIC isso slow that the conversion period of100 ps is over long before the PEEK andPOKE commands have been executed.With some analogue signal sources, it maybe necessary to extend the proceduresomewhat. If. for instance. the source con-nected to the multiplexer inputs is highimpedance, it takes a while (relativelyspeaking, of course) before the signal ispresent on pin 6 of the converter. This iscaused by the time constant of thesource's output impedance and the inputcapacitance of ICI. This little difficulty isresolved by two identical POKEs in quicksuccession to the digitizer before a PEEK.

2

DI2V5

V

4,2

StRnv

DO

01

02D3

04DS

DS

D7

0V

O

5V0

2

OO

OO

O

O

11

121 3

0

O

8

O 11

5VO

P

C1 R3

LM 10y 16V336

R2

5000

7

IC5

Vref2

D7

6

18

91 10

5

3r1 201 2

ffffCs

DO17 DI

I16

D2 !di14

D3ADC

CLK134

3 0804

D9

0 RD

Vin

2

/ 1 7

Vr-f. in V- -A me eng. D

/7

DO

D2

13

12

-a D3

8 10

10 6E2C El

CLK

DO

01

02

IC200

74 01LS 02 6173 D3 -

3

NI ... N4 = IC4= 74LSOO

19

R4

C2

150p

5V

11

10

9

16

CLR 15

0C1 0C2

2j

LM 336

6-0

let01

A 1C3 [238

0 :4051 5

6

7

VEE

4 8

al

5V

IC4

9

PI, multturn

*see test

K1

3 1

12 4

5 6

2 7 0O

85083-2

2

4

6

7

5-50

3 digitizerelektor may 1985

Parts list

Resistors:

RI = 2k2R2 = 1002R3 = 4k7R4 = 10 kP1 = 500 Q multiturn preset

Capacitors:

Cl = 10 mi16 VC2 = 150 pC3...C5 = 100 n

Semiconductors:DI = LM 336, 2.5 V (seetext)

ICI = ADC0804IC2 = 74LS173IC3 = 4051IC4 = 74LS00IC5 = LF 356

Miscellaneous:

21 -way pcb connector,reversed configuration, toDIN 41617

9 -way pcb connector,reversed configuration

PCB 85063

Figure 3. Printed circuitboard for the digitizer. Asshown in photograph 2this fits nicely into one ofthe slots of the universalI/O bus.

5-51

programmable array logicelektor may 1985

flexibility andhigh speed at(relatively) lowcost

PAL is a registeredtrademark of MonolithicMemories of the USA.

matrix = array

CPU = centralprocessing unit

RAM = random accessmemory

EPROM = erasableprogrammableread-onlymemory

PIA = peripheral interfaceadapter

PIO = parallel input output

It is well known that programmable ROMs (read-only memories) canbe used not only as a logic building brick, but also as a Booleanoperator or complex encoder. For some years now, there has been abetter, more flexible, and, last but not least, cheaper alternative tothe usual bipolar PROM (programmable ROM): PAL (programmablearray logic), not to be confused with the widely used colourtelevision system of the same name (or rather, acronym), or with PLA(programmable logic array).

programmablearray logicA PAL device is basically a matrix withthe same logic arrays as PROMs and PLAs,but, whereas PROMs use fixed AND arraysand programmable OR arrays, and PLAsuse programmable AND arrays and pro-grammable OR arrays, the PAL uses pro-grammable AND arrays and fixed ORarrays. In all three types of device, theAND array outputs feed the OR arrays.The PLA provides the greatest flexibilityfor executing logic functions, since theyafford complete control over all inputs andoutputs. Unfortunately, they are veryexpensive, very difficult to understand,and, moreover, they require special pro-grammers. PROMs, on the other hand, areeasy to program, relatively inexpensive,and readily available in a variety of sizes.The PAL combines the low cost and easyprogrammability of the PROM with muchof the flexibility of the PLA.In spite of the ever increasing density ofLSI ICs and VLSI ICs. designers still need'normal' ICs to form the link betweenCPU, RAM, EPROM, PIA, PIO, and othersections of a computer. When the circuitsare very complicated, it becomes quiteclear that these 'normal' ICs are not veryflexible. Because the only solution is touse great quantities of these ICs,designers have for years been trying touse, often successfully, bipolar PROMs aspseudo logic networks. A PROM program-mer enables an empty matrix to be codedwith a complicated logic pattern inseconds, resulting in input and outputcombinations that can be converted intoBoolean algebra. An example of this is theanalytical video display (Elektor, May1984), in which a PROM codes the colourinformation (RGB). Bipolar PROMs are alsoeminently suitable for use as addressdecoders.The usefulness of PROMs is, however,hampered by the, binary speaking, verylimited number of possible input and out-put combinations. For example, if a circuitwith ten inputs and eight outputs is to pro-vide thirteen output functions, it would bevery wasteful to use a 1 K x 8 PROM,

because of the possible 1024 input and256 output combinations only 13 would beused. It is clear that one of the goodpoints of a PROM is that for a givennumber of inputs it provides all possibleoutput combinations, but a drawback of itis that the number of input variables israther limited.

Fusible link technologyMany of you may remember the program-mable diode matrices of the sixties: eachcrossing of a matrix was as it were a fusewhich had to be blown to eliminate an ORfunction on the relevant line. Later camePROMs which had the facility to connectinput variables into an AND matrix (seefigure 2a). Each input variable is con-nected to all other input variables. In com-puter language, the input variables(left-hand column) are the addresses, andthe output variables (right-hand column)are the data. The choice between thevarious AND functions is effected by aprogrammable OR matrix. The PROM offigure 2a is shown programmed infigure 2b. Some of the fusible links havebeen blown, so that the logic level of therelevant outputs is 0. There is a total of 24possible combinations.The internal structure of a PAL devicewith four inputs and four outputs is shownin figure 3. The only visible differencewith figure 2b is that here the AND matrixis programmed, while the OR matrix isfixed. A further look at figure 3 shows thatan intact fusible link may correspond to alogic high or low.PAL devices are available in numerousvariant forms: number of inputs - 8, 10, 12, 14, 16, 18,

or 20; number of outputs - 2, 4, 6, 8, or 10; buffered outputs - feedback to inputs

possible; programmable inputs and outputs; arithmetical functions.Furthermore, it should be noted that PALdevices can be actuated with a normalPROM programmer.

5-52

A PAL for every applicationTable 1 lists a number of current PALdevices of which the logic symbols aregiven in figure 5. The part number ofthese devices also defines their logicoperation; it consists of the acronym PAL,followed by the number of array inputs,the output type (see below), the numberof outputs, the speed and/or power, thetemperature range, and the type ofpackage.The output types are:

H - active high; L - active low;111 C - complementary, i.e., active at either

logic level; -

II R - registered, i.e., logic level may beretained with a bistable and fed back tothe programmable AND matrix;

II X - exclusive OR registered;I A - arithmetic registered.Figure 4a shows the simplified structure ofan L type PAL with one input and the cor-responding output. Figure 4b shows asimplified structure in which the output isfed back to a point on the matrix where it

1G BR

R V B

RIB

R19

91 71 61 51 41 3 2

R20

5V cc 2 2(-)3 E_-.) IC13

82S23

12 V

5 V

EOOF

fG

16

14

2

13

15

12

4

11

6

o

115

C124010

3 14 5 7 91111

12113 4 21 31 51

I10

110'688;8 021C11 01

CLK 1. 4040 00

TS 211

12 V

5

7

9

5V

85051-1

Logic symbolsA number of logic symbols are used in this article, which are neitheraccepted by the British Standards Institute. the American National Stan-dards Institute, and the International Electrotechnical Commission, norstandardized throughout the electronics industry. None the less, they havebeen informally adopted by many IC manufacturers, because they show aclear relation between the chip layout and the logic diagram.

A

A

An input signal is always applied to two buffers which make the non -inverted as well as the inverted signal available at their respective outputs.To simplify this, the two buffers in PAL symbology are drawn as a singlebuffer with two outputs as shown above.

-1=1- -c\f-A BCD

A.B.C.D A -B -C -D

Logic gates and their numerous matrix -shaped inputs are also drawn in asimplified manner. Intact fuses are represented by crosses at the cross-ings of the relevant lines.

As long as all the fusible links of a gate are intact, they are not shownseparately, but instead a cross is drawn in the gate symbol itself. The out-put of such a gate is always logic low.

programmable array logice!ektor may 1985

Figure 1. This illustratesthe use of a bipolarPROM for the coding ofan RGB signal.

5-53

programmable array logicelektor may 1985 2a b

inputa

0 11

41 4

V

PROM16 words x 4 bits

(empty)

1'V

programmableOR envy

D T D

D

D

fixed AND array

Figure 2a. A PROM con-sists of a fixed AND arrayand a programmable ORarray; when all fusiblelinks are intact, all out-puts are logic high.

Figure 2b. When a fusiblelink is blown, the relevantoutput becomes logiclow. The inputs areaddresses, the outputsare data.

Figure 3. In contrast to aPROM, a PAL consists ofa programmable ANDarray and a fixed ORarray.

41-

Inputs

ff. 110 fel111 II 1 9

0 0 1 1

afi

II 1 f 1

(I 1 0a 1

1 1 1outputsI 1 1 1

1 I/ 0 0aa

I 1 1

1 0 1 s

1 0 1

1 1 II 11

1 1 9 1

1 1 1a

1 1 1 1

44402 Da 0, Op

65051.2,

PROM16 words x 4 bits

(programmed)

;: B:

T D

2DDDDD

fixed AND array

. /triable Fmk inU.

progrunosableOR array

aI

I

a

a

a

03 02 01 02

output.

85051-2b

3

1,3

PAL: 4 inputs; 4 outputs

I IV'FV\4i;D

tnnIcammtbLeAND array

firable link intact ='D'" or -1-

. Imedlnoriprogramnsable)connection

band OR array

01051.1

is converted into an input. This facility isof interest in the design of a shift registeror a data loop. When the output inverter isswitched over to high impedance, the out-put line can be used as an input.The output of an R type PAL in figure 4cis buffered by a bistable and fed back tothe matrix. The feedback allows the PALto remember the previous state and it canalter its function based upon that state.The Q output of the bistable may be gatedto the output pin by enabling the activelow three -state inverter. This inverter canbe switched to high impedance via a linecommon to all outputs.Figure 4d shows how the sum of productsis XORed at the input of the D typebistable. This function is of interest in theHOLD operation of counters.Arithmetic functions are executed bygated feedback to the XOR device asshown in figure 4e. This set-up makespossible the combinations I+ Q,I +Q, and I +0 which are fed to the

matrix. This arrangement enables a sharpreduction (about 12 to 1) in the number ofcomponents as compared with standardlogic circuits.

First stepsAn example of simple programming isillustrated in figure 6: (a) shows a circuitthat is required to be replaced by a PALdevice; (b) is a virgin PAL device chosen

5-54

Table 1. programmable array logicelektor may 1985

PALtype inputs

IIItputsMI

program -mableI/Os

registers functions

10H8 10 8 AND -OR12H6 12 6 AND -OR14H4 14 4 AND -OR '16H2 16 2 AND -OR10L8 10 8 AND -OR -INVERT12L6 12 6 AND-ORINVERT14L4 14 4 AND -OR -INVERT16L2 16 2 AND -OR -INVERT16C1 16 1 AND -OR 'AND -OR -INVERT16L8 10 8 6 AND -OR -INVERT16R8 8 8 AND -OR -INVERT -REGISTER16R6 8 8 2 6 AND -OR -INVERT -REGISTER16R4 8 8 4 4 AND -OR -INVERT -REGISTER16X4 8 8 4 4 ANDORINVERT-X0R-REGISTER16A4 8 8 4 4 AND-CARRY-OR-XOR-INVERT-REGISTER

4 aSMUTS

bPOUTS PIEVJOILLZ001.0

C

type L 8505144

POUTS, OMDSACS MO 1,0

type L- I/O 8505t -4b

dPMTS. MTUILLGO tO

1type R

I I

e

I:1111111ffili

..VT;. MIDS.= A.01.0

550.51-4c

ROCS

typo X 550514d

III

iHI I

trim A 55051-4s

0

Figure 4. This illustratesthe five different types ofPAL; for simplicity's sake.only one input and oneoutput are shown.

5-55

programmable array logicelektor may 1985

PAL12H6

PAL16C1

PAL14L4

PAL16L8 PAL1688

PAL16X4

Figure 5. Logic symbolsof fifteen current types ofPAL.

Figure 6. A logic circuitthat is to be replaced bya PAL device.

PAL14H4

PAL10L8

PleaEll 0.441.

ow CD

Ell 11041... FC

°I 111-4111. Ell

alEl =N seI w.41ul 1111"'a. wiA,Iii so iE

O. nietMLEal 1111j1MAIM

PAL16L2

Eirat.Ell =CDum T,

ull iiik cc

i1311 1.OWal NW

cr.

I 11.11,,

PAL1686

PAL16A4

-0,

02

03

04

as described below; and (c) is the pro-grammed PAL.As more than half the output signals areinverted, an L type is indicated. To obtainten inputs and six outputs, the choiceshould fall on a type 101.8, but figure 5shows that not one of the NOR gates inthis type has more than two inputs. Afurther look at figure 5 shows that the type12L6 has two NOR gates, each with fourinputs. Since one of the outputs in figure6a, Q5, is a combination of three signals,the type 12L6 is suitable for our purpose.The outputs in figure 6a may be defined,according to De Morgan's Theorem, asfollows:

01 =11 =01 =1102 = Ti- 12 2 02 = 11 +1203 = 11 + 13 2 03 = T 13

04 = F3- - 14 2 Q4 = - 14

05 = - 15 16 + 17 + 18 19

05= 13-15.16+ 17+18 19

Q6 = 18 19 + 13 - 17 - 19 11006 = 18 19 + Fa - 17 - 19 - 110

As stated, the PAL type 12L6 shown infigure 6b, has all its fusible links intact. Toeffect that 01 = II and Ql = II, the threeunused inputs of NOR gate Ni in figure 6cmust be logic 0: the fusible links on lines,9, 10, and 11, therefore, remain intact. Online 8, only the link with line 2 remains: allother links are blown. Output Q2 com-bines Il and 12, but because it is inverting,the result is Q2 = 11+12. Only the linkswhich connect the inputs of NOR gate N2to columns 1 and 2 are retained: i.e., theinverting output of II and the non -invertingoutput of 12.For Q3, only the input line of AND gateN3 to which the non -inverting outputs of Iland 13 are connected is needed.The coding of Q4, 05, and Q6 is left toyour own ingenuity: it is good practice!The results are shown in figure 6c in anycase.Another example concerns the replace-ment by a PAL of the logic functionsshown in figure 7a. As you see, it con-cerns an inverter, an AND, OR, NOR, andXOR gate, and a NAND gate with threeinputs. That gives a total of twelve inputsand six outputs which are active high.From the logic symbols in figure 5, it iseasily seen that a 121-16 is required. Whenthat type is programmed properly, thefuse pattern of figure 7b will ensue.

ProgrammingThe programming voltage should be 11.5 V± 0.5 V, while the programming pulsesshould have a width of 10...50 ps. Tomake it possible for the fusible links to bearranged in turn, the matrix has beendivided into two groups: one for the linkson lines 0...31, and the other for lines32...63. In matrix columns 1...31 selec-tion takes place with the aid of signalsA0...A2 and 00...03. The connections tothe IC are dependent on whether the firstor the second group of lines is beingaddressed. Tables 2 and 3 show how the

5-56

6b PAL 12L6(virgin)

programmable array Ionicelektor may 1985

INPUTS (0-31)a - 11001/- MAW

E>

III

B Dc

III

air3516b

6c PAL 12L6(programmed)

11ammrsaprormaixrwElp/

11

-

1118-Doctls-* Ti h

4s ry,v,i.,7"14

. ,

85051 -Se

Figure 6b. Logic diagramof a virgin PAL type 12L6that is suitable for replac-ing the circuit of figure6a.

Figure 6c. Fuse pattern ofthe 12L6 after it has beenprogrammed in accor-dance with therequirements of figure 6a.

5-57

programmable array logicefektor may 1985

Figure 7a. Anotherexample of a PAL devicereplacing a number ofstandard logic functions.

Figure 7b. Fuse pattern ofthe 12H6 after it has beenprogrammed in accord-ance with the require-ments of figure 7a.

7a

PAL 12116

115051.7

form. There is a special program availablefor this: PALASM (PAL assembler), writtenin FORTRAN IV, that translates the logicequation to a PAL fuse pattern. This soft-ware has been designed by MonolithicMemories. Unless you use it often, it maynot be worth your while obtaining it,although making fuse patterns without itwill not be easy, particularly when youfirst start.The PAL Databook published by NationalSemiconductor gives programming tablesfor the fifteen PALs National produce.Apart from this book, the PAL Handbookpublished by Monolithic Memories is alsostrongly recommended. The more you

7bC

o

F

'

N

PAL/2116

R.. M. II II IN NV

R

C4

A

'8

g D

BD

D

B D

35051-7b

addressing should take place, while figure8 gives the connections for both groups.Figure 9 gives the timing diagram whichalso shows the programming and verifyvoltages. It does happen from time to timethat certain links refuse to be blown; inthat case, reprogramming after testing isnecessary, and may be necessary again.It cannot be pretended that every retaileris able to program PAL devices, even if hestocks them, but there are some! You haveto draw a matrix as shown in figures 6band 7b (but, of course, relevant to yourparticular device!) and convert that into acode that is acceptable to the program-mer. That means that the addresses anddata must be converted into hexadecimal

become engrossed in PALs, the more theywill grip you!

Literature:PAL HandbookMonolithic Memories LtdMonolithic House1 Queens RoadFarnboroughHants GU14 6DjTelephone: (0252) 517431

PAL DatabookNational Semiconductor (UK) Ltd301 Harpur CentreHome LaneBedfordTelephone: (0234) 47147

N

5-58

Table 2. programmable array logicelektor may 1985

inputline

pin identification

number 17 16 15 14 13 12 11 10 LIR

0 HH HH HH HH HH HH HH L R1 HH HH HH HH HH HH HH H R

2 HH HH HI -1 HH HH HH HH L HH3 HH HH HH HH NH HH NH H HH4 HH HH HH HH HH HH L HH R5 HH HH HH HH HH HH H HH R6 HH HH HH HH HH HH L HH HH7 HH HH HH HH HH HH H HH HH8 HH HH HH HH HH L HH HH A9 HH HH HH HH HH H HH HH R10 HH HH HH HH HH L HH HH HH11 NH HH HH HH HH H HH HH HH12 HH HH HH HH L HH HH HH R13 HH HH HH HR H HH HH HH R14 NH HH E11-1 HH L HH HH HH HH15 HH HH NH 1-11-1 H HH HH HH HH16 HH HH HH L HH HH NH HH R17 HH HH HH H HH HH H1-1 HH R18 HR HH HH L HH HE( E11-1 HR HH19 HH HH HH H HH HH HH HH HH20 HH HH L HH HH HH HH HH R21 HH HH H HH HH HH HH HH R22 HH F11-1 L HH HH HH HH HH HH23 HH HH H NH HH HH HH HH HH24 HH L HH HH HH NH HH HH R25 H L HH HH HH NH HH HH R

26 HH L F11-1 E11-1 HH HH HH HI -1 HH27 HH H HH HH NH HH HH HH HH28 L HH HH HH HH HH HH HH R29 H HR HH HH HH HH HH HH R30 L HH HH HH HH HE( NH HR HH31 H HH HH HR F11-1 HH HH HH HH

Table 3.

productline

number

pin identification

03 02 01 G0 A2 Al Ao

0,32 R R R VpH R R R1,33 R R R VpH R R HH2,34 R R R VpH R HH R3,35 R R R VpH R HH HH4,36 R R R VpH HH R R5,37 R R R VpH fill R HH6,38 R R R VpH HH HH R7,39 R R R VpH HH HH HH8,40 R R VpH R R RR9,41 R R VpH R R R HH

10,42 R R VpH R R HH R11,43 R R VpH R R HH HH12,44 R R VpH R HH R R13,45 R R VpH R HH R HH14,46 R R VpH R HH HH R15,47 R R VpH R HH HH HH16,48 R VpH R R R R R

17,49 R VpH R R R R HH18,50 R VpH R R R HH R19,51 R VpH R R R HH HH20.52 R VpH R R NH R R21,53 R VpH R R HH R HH22,54 R VpH R R HH HH R

23,55 R VpH R R HH HH HH24,56 VpH R R FIR RR25,57 VpH R R Ft R R HH26.58 VpH R R R R HH R27,59 VpH R R R R HH HH28,60 VpH R R R HH R R29,61 VpH R R R HH R HH30,62 VpH R R R HH HH R31,63 VpH R R R NH HR NH

L = Low-level input vo tage, IVIL)H = High-level input voltage WIN)HH = High-level program voltage, (V1H1-1)R = 10 k Ohms to 5.0 VVpH = Programming Pulse

.cc

8

Li

Li

10

0...31

OD vcc

10

11

12

13

14

15

15

17

GND

00

oi

02

03

AO

Al

A2

LIR

CLOCK

2

16

15

78

12

11

32...63

Ii CLOCK VCC 3E IO uR 3E 11

AO EE 12

Al EE 13

A2 2EI4 00 2

C15 0114

E .6 02 2E17 03 2E GND OD 3

85051-8

9IMPI

00

11.5

Ali115V

I. LA. A I I

,111

S 1

Tp . 4 Sv--.-4-4.

115V v,. >100.s

CLOCK

115V

13.4

10 .. 50 -4---> 100.1

135051.9

Figure 8. During the pro-gramming of a PALdevice, the connectionsdepend on the group oflines that are being pro-grammed.

Figure 9. Timing diagramcomplete with test(verify) voltages.

5-59

automonitorelektor may 1985

displays themost importantinformation adriver needs toknow

automonitor"A driver's multimeter" is onepossible description of thiscircuit, which is born from motormanufacturers' ignorance of amodern driver's needs. In spite oftheir loudly -heralded (and veryexpensive) trip computers, veryfew cars today are fitted with atachometer, fewer still with abattery charge indicator andalmost none with a fuelconsumption meter. Everyconscientious driver knows howimportant these figures are, farmore important, actually, thanroad speed. There has long beena thriving trade in this sort ofinstrument in car accessoriesshops but never, until now, havethe three been combined in oneunit.

This automonitor is a unique instrumentbut we cannot claim that it is really revol-utionary. For that reason we will refrainfrom singing its praises and concentrateinstead on answering a few pertinentquestions.The monitor provides a read-out of fuelconsumption in litres per hour. A milesper gallon indication would appear morelogical, but there are several importantreasons for rejecting it. Any distance -related measurement, be it in miles orkilometres, would require a tap -off fromthe car's speedometer cable. This is atbest difficult and in most cases virtuallyimpossible. The litres per hour reading(familiar to pilots) is achieved with a veryreasonably -priced circuit - and who cancomplain about that? And what about thechoice of litres rather than gallons? Thathas now become a pre -requisite foralthough we still think in terms of milesper gallon we buy our petrol in litres.The automonitor is not a trip computer,that point is clear. The reason for this ismainly one of cost. The electronics in-volved are well known and pose no fearsfor Elektor's designers. The pick-ups andother hardware are far from cheap,however, and pose other problems, so that

5-60

this is a project we could not justify eithereconomically or for its own sake.

Fuel consumptionThe tachometer section of this circuitdoes not need any introduction, especiallyas we published a similar design asrecently as September 1984. The batterycondition indicator does not use a singleintegrated circuit. It does not need one,nor does it require any introduction here.A car's fuel consumption depends on anumber of factors. As the curves offigure la show, one of the most importantis the relation between engine speed andtorque and power. The slope of the fuelconsumption curve increases sharply afterit passes a very important point, namelythe engine speed at maximum torque. Atmaximum torque the engine is at its mostefficient, so above this point it becomesless economical.

The curves of figure lb show the import-ance of those in figure la. This diagramactually shows an example of a car's fuelconsumption in the different gears. Firstgear needs to have a very low ratio toovercome the car's high inertia (its reluc-tance to move), but that makes it veryuneconomical. This gives a clue as to whythe fuel consumption indicator in thenewest BMWs is graduated in 2 litre stepsfrom 2 to 30 litres per 100 km. Theeconomical parts of the graphs for the firstthree gears are quite linear so the point atwhich to change gear is obvious.

The block diagramThe three block diagrams in figure 2 showthe sub -assemblies of the different parts ofthe circuit. Given their simplicity it will beno surprise that we now move straight onto...

la0

E_cgO

LL 12 80

T

g-

11 70

10 60

9 50

8 40

7 30

6 20

5 10

0 0

hiasienurneogine spent

Maximum parser

Powerw

./.

Camumpiion.:,

Torque

0 1000 2000 3000 4000 5000 6000 -.-4114. Engine speed (rpm)

0 30 60 90 120 150 iso --4P- Speed (km/h)165

85054 - ta

lb20

18

16

E 14

012

.010

0. 8

60U

437Li -

4

2

0

--r -1-1 1st gear

0

14th gear (lowI -ratio)

IS0 I/ 2nd gear 361 gear IA

05...

Ie .

e 4th gear (high .ratio), .0.

oe .......d.- ..._r. i ... ...*

....-°'

... .. '....

se. ..............

. .. , ....." . _ _

w

5th gear or overdriveNo

I

20 40 60 100 120 140 160

85054 - lb

automonitorelektor may 1985

Figure la. These are thecurves typical of a carengine. It is obvious thatmaximum torque andmaximum power areachieved at differentengine speeds.

Figure lb. Here we seegraphs illustrating therelation between the gearselected and the fuel con-sumption.

--N. Road speed (km/h)

5-61

automonitorelektor may 1985

Figure 2. This triple blockdiagram shows the threesub -sections of thecircuit:a is the battery conditionindicator;b is the tachometer; andc is the fuel consumptionindicator.

O

12 V

Battery

C.B. points

flow sensor

Windowdiscriminator

Non-retriggerableMMV

-0-

(\

Red

Green

Red

85054-2

...the circuit diagramThe sub -assemblies of the circuit aredivided by the dotted lines in figure 3.This will make it easier for us to treatthem as distinct entities and deal withthem one by one, starting with thesimplest.

The battery charge indicatorThe heart of this circuit is a TCA 965, awindow discriminator IC designedespecially for this sort of application. Thereason for using this chip will be obviouswhen we say that this circuit shows thecar battery condition not as a number butrather as a point somewhere between thegiven maximum and minimum values. TheTCA 965's window, as you must nowguess, spans this range.

The input voltage is applied to pin 8 ofIC4 which then compares it to the two ref-erence values. These upper and lowerthresholds are applied to pins 6 and 7 andare set by presets P3 and P4. The result ofthe comparison shows whether the inputvalue is above, below, or within the refer-ence window. These three conditions aresubsequently displayed by LEDs D3...D5.The references for IC4 are taken from thechip's own stable reference voltage(available on pin 10) and dropped torequired levels by voltage dividers(presets P3 and P4). The two voltageschosen give U6=14.5 V and U7=11.5 V. Theinput voltage is only acceptable in therange of 0 to 6 V so only part of the bat-tery's voltage can be passed to pin 8.The values chosen for R18 and R19 resultin a ratio of 4:1 between the applied

5-62

3 automonitore!ektor may 1985

Cyfr 14V5

CB. 11V5 RIB

Battery condition

12 V

indicator

it)

RI

Cl R2O10pBY

P3

k

6

10 11

1007V

IC4

TCA965

R20

13

14

P24 5 ff133311

2 03DIM R23

R21 C0

Tachometer

R5

C2Otoy6V

Fuel consumption

indicator 1C1

R3

311

C10

100

BC550C

T2

(C.0)BC550C

ffD4.D5 re-]

CA

05> 14V5t1t/5 113 'AVE,

04< 11V5

4

R6

0

C5MEP

72ri

C RC0

B MMV1

at a2

3Q 4y

O117

Re

MMV1 ',41C2 = 741_8121

IC3

78050

D3- vv.*.

12 V0

ca

loo$7175y

voltage and that measured at pin 8. TheTCA 965 compares this input voltage tothe reference thresholds and then givesits verdict. If the input is greater than theupper limit, pin 2 goes high; if it is belowthe lower threshold, pin 13 goes high.Input voltages that fall within IC4's win-dow cause pin 14 to go high. If the batteryvoltage is exactly 11.5 V or 14.5 V, resistorsR20 and R21 prevent the LED in questionfrom flashing. The three outputs of the ICthat we have mentioned are open collec-tor outputs, which means that they can beconnected directly to a LED.

The tachometerThe voltage tapped off the car's coil is fedto transistor T1 via a voltage divider,R9 -R10, which serves as a protection

against excessively high voltages causedby the opening of the contact breakerpoints. The resulting voltage is applied tothe monostable consisting of Ti and T2.The pulses thus produced have a constantwidth that is determined by the values ofR14 and C10. The frequency of the pulsesis directly proportional to the enginespeed and, of course, so also is theresulting average voltage. A preset, P2, isthen used to enable part of this voltagefrom the collector of Ti to be applied tomoving -coil meter M2. This then gives adisplay of the engine speed.

The fuel consumption indicatorThis section of the circuit is made poss-ible by the JG52.01 inductive sensor con-nected to points A and B in figure 3. Thefuel flows through the sensor causing the

Figure 3. All three sub-sections are clearlydefinable in this circuitdiagram. Each is quitestraightforward whenconsidered on its ownbut the three combinedform a powerful unit.

5.63

Parts list 4Resistors:

R1,R2,R14 = 47 kR3.114 = 100 kR5,R13 = 220 0R6 = 4k7R7 = 27 kR8,R9,R20 = 10 kR10.R11,R17 = 1 kR12 = 5k6R15 = 470QR16 = 3k3RI8 = 8k2R19 = 2k7R21 = 100 0R22...R24 = 560 QP1 = 100 k presetP2 = 500 Q presetP3,P4 = 10 k preset

Capacitors:

C1,C2 = 10 p/6 VC3,C4,C10,C12 = 100 nC5 = 22 nC6 = 820 nC7 = 1 y/6 VC8,C9,C11 = 100 gi6 V

Semiconductors:

D1,D2 = 1N4148D3 = LED, greenD4,D5 = LED, redIC1 = 311 (8 -pin DILpackage)

IC2 = 74LS121IC3 = 7805IC4 = TCA 965

Miscellaneous:flow sensor, Semitronic52.01 I+ 8500 pulses/litre)

M1.M2 = moving -coil me-ter, 500 A f.s.d.4 -core screened cable,c. 2.5 m

Figure 4. This printed cir-cuit board greatlysimplifies the job ofbuilding the project. Italso provides a reliabilityand professional appear-ance that would other-wise be out of thequestion.

vanes of the pick-up to turn. A sinusoidalsignal is then output with an amplitudeproportional to the speed of the vanes.This signal is applied symmetrically to theinputs of a Schmitt trigger voltage com-parator, which effectively suppresses anyparasitic effects that the engine mightcause. A 311 is used for IC1 because of itsability to handle inputs a hundred timessmaller than a 710C, for example. Thelow -frequency sinusoidal input signal isconverted to a rectangular pulse train.This is output at pin 7 of IC1 and thengoes to input B of a 74LS121 non-retrigger-able monostable multivibrator. Triggeringoccurs at a particular input voltage and isnot directly related to the width of theedge (in this way the circuit is not at allprone to parasitic effects). This triggeringis always stable, even when the inputvoltage varies by as little as 1 volt/second,due to the Schmitt trigger fitted to input B.An internal regulation circuit ensures stab-ility during the output pulse, which isalmost completely independent of supplyvoltage and ambient temperature. Thepulse duration is defined by 7' = 0.7Cez R...Output Q of the MMV continually outputspulses of the same width but separated bydiffering intervals so that the resultantaverage voltage is variable. Because CB

has quite a large capacitance, themonostable is very temperature -stable.The signal output by MMV1 is applied tolow-pass filter R8/ C9 and the averagevalue of the pulse train drives moving -coilmeter Ml, which provides the display. Thecurrent flowing through the meter isdetermined by preset Pl.Power for the circuit is, of cource, pro-vided by the car's battery. The tachometerand the fuel consumption indicator need astable +5 V and this is supplied via IC3.To enable it to do its work properly, thebattery condition indicator is connectedstraight to the battery. So much for theoryof the circuit; time now to move on to themore practical parts of this project.

Construction and installationThe printed circuit board layout shown infigure 4 can be used to greatly simplifyconstruction of the project. There are nospecial preacautions about assembling thecomponents on the board. Connectionpoints to components mounted off theboard and away from the circuit areclearly marked. The two meters are con-nected to Ml and M2; LEDs to IC -D5-4-3;the fuel -flow sensor to A and B; the bat-tery to + and 0; and the c.b. points to the

5-64

5

Fuel tank

A

Fuel

pump

0 e

Engine

115054 -5 a

iSZ 5a-54

stria-az

white arrow. If desired, all these pointscan be fitted with soldering pins.Before fitting ICs 1, 2, and 4 connect thebattery's +12 V to the circuit and checkthe operation of IC3 by measuring the+5 V at pin 14 of the socket for IC2. Movethe wipers of all presets to mid -positionand then fit the integrated circuits. Con-nect the meters and LEDs to the boardwith short lenghts of wire. Using a 4 -wayscreened cable, make the five connec-tions to A, B, the c.b. points, and the bat-tery. The screening of the cable is usedfor the link from the negative battery ter-minal to point 0.Now we come to the fitting of the sensorin the fuel feed line. This can be done inthree different ways, as figure 5 shows. Ifthe car to which the automonitor is fittedhas no return flow line from carburettor tofuel tank, the sensor is fitted as shown infigure 5a. The sketches in 5b and Sc arevery similar, differing only in that one hasa carburettor, the other a fuel injection

pump. In both cases the sensor is fittedbetween fuel tank and pump. The returnflow line from carburettor or injector isthen broken at the fuel tank side. A (non-ferrous) T -piece is fitted between thesensor and fuel pump to accept theexcess return fuel flow.When fitting the sensor and T -piece, makesure that they are fixed in place correctlyand firmly. If the T -piece is made of fer-rous metal (that is subject to magnetism), itcan corrupt the reading given by thesensor so pay careful attention to this. It isalso wise to keep the sensor away fromhot parts of the engine. Before connectingthe sensor to the circuit, make sure thatthe car still works. If it fails to start, theproblem is quite likely to be found in thefuel system. If it does still work, theremaining electrical connections (to A andB) can be made. Should the engine nowfail to start, this is probably an indicationof a short in the circuit.

automonitorelektor may 1985

Figure 5. There are threepossible ways of mount-ing the fuel -flow sensor,depending on the layoutof the car's fuel system.All three are explained inthe text.

5-65

automonitorelektor may 1985

Figure 6. If you do nothave access to a variablepower supply, this auxili-ary circuit will be handyfor calibrating the batterycondition indicator.

85054-6

CalibrationIn this, as in most Elektor projects, wehave devised a calibration procedure thatdoes not require any special test equip-ment. We will start with the battery con-dition indicator. The auxiliary circuitshown in figure 6 is used for this. Theautomonitor is connected to + and 0 offigure 6 instead of to the car battery. Turnthe switch to position 'a' and trim preset Puntil LED Da lights. The voltage across +and 0 is then 14.5 V exactly. Adjust presetP3 until the 'high voltage' LED goes outand the green LED is lit, indicating avoltage of 11.5 V exactly. Turn P4 until thegreen LED goes out and the 'low voltage'LED lights. The circuit can now again beconnected to the car battery, whose con-dition is then easy to check.If you have a variable power supply, thiscalibration is greatly simplified. Apply14.5 V to + and 0 on the circuit and trimP3. Change the applied voltage to 11.5 Vand set P4 correctly. Calibration of thissection is then completed.When the engine is off, the 'low voltage'LED may light (unless the battery is new).This is nothing to worry about, and assoon as the engine is started this LED willgo out and the green LED will light. The'high voltage' LED will only light if there issome electrical fault, in the car's regulator,for example.Only one preset is provided for calibratingthe tachometer, namely P2. This must beset with reference to an accurate

11111111111

tachometer but will require only a fewminutes of your friendly mechanic's time.Connect both tachometers to the engineand let it run at a reasonably high constantspeed (about 3000 or 4000 rpm). Trim P2until the reading is the same on bothtachometers.Calibrating the fuel consumption meter isa bit more involved. It will require sometime and care to set it correctly becauseof the tolerances of components, sensor,voltage comparator gain, and so on. Thisis the procedure we suggest: Turn preset P1 to mid -position. Refer to the car's handbook to find out

what engine speed corresponds tomaximum torque in top gear. Find a quiet motorway (if that is still

possible!) and stop at the first servicestation and fill the fuel tank to the brim. Drive another 15 or 20 miles along the

motorway at the engine speed corre-sponding to maximum torque. Note theposition of the meter's pointer. Once again stop at a service station and

fill the fuel tank to the brim. Calculate the fuel consumption (in

litres/hour) knowing the distancetravelled, time needed, and fuel used. Mark this position on the meter scale. Mark the position of the needle when

the car is idling. The average 1500 ccengine uses about 31/h when idling. The fuel consumption at a constant

70 mph is a well -published figure forcars these days so this can also be markedon the meter. It is a simple matter ofarithmetic to convert it to litres per hour.As we have already said, a car is at itsmost efficient at maximum torque, so themeter scale could be marked green up tothis point and red above it. In this way it iseasy to see if you are driving economi-cally or not.

Final pointsThe fuel consumption meter section ofthis circuit, in particular, will soon pay foritself. The indication it gives is accurateenough to ensure this. With use, you caneven add more points to the scale so thatit will begin to resemble the one shown inthe photo. Do not expect the scalegraduations to be linear because this isnot so. The number of pulses per litre pro-vided by the sensor is not constant: at11/h it is about 5000; 8000 at 31/2 1/h; andabout 10 000 at 91/h.If you do not wish to have both fuel con-sumption and engine speed simul-taneously displayed, a single moving -coilmeter could be used. A double -polethree-way switch will then have to be con-nected between the meter and the fourpoints intended for the original pair ofmeters. Similarly, an on/off switch can beconnected in the 12 V power line if youdo not want to leave the circuit perma-nently on.Finally, one important point. Make surethat the unit is mounted securely andsafely in the car. Above all, be sure that itcannot foul anything in an emergency. II

5-66

panorama mixerelektor may 1985

J. Wallaert

One of the most popular fields of electronics, certainly for hobbyists,has always been audio. This is one of the few areas in which you canactually hear the results of long hours spent designing or building acircuit, which could be anything from a single -chip radio receiver upto a polyphonic synthesizer with all the trimmings. A small part ofthis field, namely home recording, is becoming ever more popular inits own right. For all enthusiasts of this 'bobby' we have nowdesigned a simple mixer with an unusual feature - a facility forplacing a sound anywhere you like in the stereo 'spectrum'.

panorama mixera four -channelmixer andbalance controlin one

Figure 1. This circuitenables a number ofsignals to be mixed, witheach being given aspecific position in thestereo image. Each of thesignals may come from adifferent source but mustbe 'mono. In effect thismixer is an alternative forthe more complex ver-sions in which a phase -shift is used to set theposition of a signal.

115V

C15 V

ICI IC2

0 0

PI

In home recording the quality of thesound is all-important so it is quite under-standable that most enthusiasts areprepared to spend a lot of time andmoney to get this right. Unfortunatelythere is then very little left over for specialeffects that can give a recording a specialcharacter of its own. The circuit shown infigure 1 has a dual function. It mixes thesignals that are presented to its inputs(four inputs are used in the exampleshown but this could be more or less) andat the same time it enables each of the in-put signals to be placed at a particular'place' in the total sound. What thismeans, actually, is that there is an in-dividual balance control for each input.

Four inputs, two outputsEach of the four input channels to the cir-cuit can be considered separately as eachis virtually independent of all the others.The number of channels used can be in-creased or decreased depending on in-dividual requirements. This is simply amatter of duplicating or deleting the rel-evant section.Consider input I as the model for all thechannels. The d.c. component of the sig-nal presented to this input is removed by

min

Cl 3 Ct 4

ICICA

31401002

IC2CA

C [jA3140

1 MIMI

cl=

electrolytic capacitor Cl. The signal thenpasses to logarithmic potentiometer P5where the volume is set. Both ICI and IC2are connected as inverting amplifierswhose closed -loop gain for a given inputis determined by the ratio of the feedbackresistor (R5 or R6) to the resistance be-tween the wiper of P5 and the invertinginput (virtual earth) of the op -amp (if weignore the source impedance of P1 andthe audio source). Moving the wiper of PIfrom the extreme to 'R' varies the gainof IC1 from two to one. while at the sametime the gain of IC2 goes from one to two.In effect this means that IC1 has a highgain while IC2 has a low gain and viceversa, so the input signal is split betweenthe left and right output channels in aratio that depends on the position of thewiper of Pl. The transfer ratio (output/in-put) of each channel ranges from zero totwo. When the wiper of P1 is in mid -position the gain of each op -amp is thesame so the input signal is split evenlybetween the left and right channels. Thewiper of PI therefore determines exactlywhere the signal is located relative to theleft and right channels. Each of the otherchannels operates in precisely the sameway. The input impedance depends onthe position of the wipers of presetsP5 ... P8; output impedance depends onthe op -amps (about 60 Q with theCA 3140s). The maximum input level isabout 7.5 Vpp.Building this circuit is quite straightfor-ward and as it is so small it could prob-ably be incorporated within some otherequipment. Current consumption dependson the number of channels used but asshown it is about 5 mA. The op -amps in-dicated give a reasonable performancebut this can be improved by selectinglow -noise types instead. The circuit canbe made more 'user-friendly' by usingslider pots for P1... P4 and P5 ... P8. It isthen possible to see at a glance exactlywhat the volume and 'position' of eachchannel is with respect to all the others. N

5-67

New books and catalogues

A science teacher'scompanion to the BBCmicrocomputerby Philip HawthorneISBN 0-333-382854 PbkPrice £9.50

Published by Higher arid Further Edu-cation DivisionMacmillan Publishers LtdHound millsBasingstokeHampshire RG21 2XSTelephone: 102561 29242As this book has only just been received, a fullreview will not be possible until one of ourfuture issues. At a first glance, we would say,however, that it looks good and interesting.

Cirkit's Spring 1.985CataloguePacked with over 4000 different componentsand associated new products for the elec-tronics hobbyist was published on 11 April. Itis available from leading newsagents through-out the country at the cover price of £1.15.

The Electronics SuperstoreCatalogueNo fe.%er than 560 pages crammed with equip-ment, parts, components, tools, testinstruments, books, and information for theprofessional and amateur electronics designer.

VEROSPEEDStansted RoadBoyatt WoodEastleighHants SO5 4ZYTelephone. 107031 644555 (Sales)

107031 641111 lAdmin)Telex: 477144

Toolrange 1985-86 CatalogueWell known to many of you, the Toolrangecatalogue for 1985-86 has increased in size yetagain to accommodate many new items,which allows Toolrange to maximize the overallservice they can provide. It is now possible toequip from the Toolrange catalogue, from thebench and chair for the operator, to the soph-isticated test equipment needed to design andmaintain tomorrow's advanced products.

Toolrange LimitedUpton RoadReadingBerks RG3 4JADirect sales line: 107341 72245Other enquiries: (07341 29446Telex: 847917 lisotip 9)

Application notes:linear action DIP switchesThis new brochure 1Bulletin No. 3711 is a com-pilcation of various application ideas for use ofGrayhill linear action DIP switches, describedand illustrated with circuit diagrams.Grayhill Inc.561 Hillgrove AvenueLa GrangeIllinois 60525Telephone: 1010 1 3121 354-1040Telex: 910-683.1850

New cases catalogueNeMy published by Imhof-Bedco StandardProducts Ltd is a sixty -page catalogue givingfull details of the company's extensive range ofstandard boxes designed to meet therequirements of a wide variety of applications.

Imhof-Bedco Standard Products LimitedAshley WorksAshley RoadUxbridgeMiddlesex UB8 2SQTelephone: 10895) 37123Telex: 24177 lib uxb g)

System 68000 VMEbusProduct Guide III 1984/85This forty-eight page colour publication pro-vides detailed descriptions of CPU boards,memory boards, serial and parallel I/O boards,interfaces, graphics subsystems, and com-plete FORCE VME systems. A software sec-tion describes the PDOS real-time andUNIX -based operating systems. Also includedare several sections application examplesshowing the use of boards and systems.

M1licrosystem ServicesP 0 Box 37Lincoln RoadCressex Industrial EstateHigh WycombeBucks HP12 3XJTelephone: (0494) 41661Telex: 837187

Databook of ceramic -basedproductsThis 224 -page databook is divided for easy ref-erence into product sections, and gives com-prehensive technical information on Sprague'srange of multi -layer monolithic ceramic -basedcapacitors, including chip; radial -lead con-formal coated; radial -lead moulded; axial lead;and dual -in -line and single -in -line packagetypes.

Sprague Electric 1UK1 LtdSalbrook RoadSalfordsSurrey RH1 5DZTelephone: 102 9341 5666Telex: 877813 13225 MI

Mini soldering stationThe Weller EC4000 electronic controlled minisoldering station has a three -digit LED read-out for temperature setting and tip tempera.ture with a resolution and setting accuracy of1°C. The electronic system uses SCR (silicon -controlled rectifier) control which ensures that

no high voltage spikes or magnetic fields willbe present on the soldering tip. In addition, thepower unit is isolated from the mains by atransformer: the heating element operatesfrom 24 V AC. The temperature range is175...450°C 6°C.

Toolrange LimitedUpton RoadReadingBerks R63 4AJTelephone: (0734122245 (3229 Fl

Low profile strip -linesocketsA new series of low profile strip -line sockets,ideal for board -to -board jumper interconnec-tion or other plug-in applications, is nowavailable from Aries. The sockets provide agas -tight contact and are available in 40 -pin(square) strip which can easily be broken downto any number of smaller strips with only onepin position being lost for every break.

Aries Electronics (Europe)Alfred House127 Oat/ends DriveWeybridgeSurrey KT13 9LBTelephone: 109321 57377 (3227 F)

5-69

elektor may 1935

New style terminal blockAs a complement to their now well establishedIMO terminal block, IMO Electronics haslaunched the 700 series range of terminalblocks. Through the use of a rising clampinstead of the standard wire protector, the newblocks lend themselves to applications where

multiple cable insertions are required. The newblocks also feature a test hole that allows a testprong to be inserted to touch the terminalrather than, as is usual, the screw head.

IMO Electronics1000 North Circular RoadStaples CornerLondon NW2Telephone: (011452 6444 ((3230 Fl

MinivacThe Minivac gives true vacuum cleaner actionto remove minute particles, and collects themin a cloth bag: this is unlike the usual com-pressed air blower which merely blows thepollutants into the air. Minivac is very power-ful, yet small, light in weight, and delicate inaction. It operates from a 9 V battery ormains -operated adapter. The RRP is £19.60plus VAT.

O & S PhotographicSouth BlockThe MailingsSimbridgeworthHertsTelephone: (02791 722208 (3228 F)

Techno-line now on-lineTechnomatic has announced the launch ofTECHNO-LINE, the new viewdata informationsystem, facilities of which include: latest news* new products telephone ordering com-ments on stock and availability reviews anddescriptions ' product data response frames and more! The telephone number of Techno-line is(01) 452 1500Technomatic Limited17 Burnley RoadLondon NWIO lEDTelephone: (011204 1177Telex: 992800 (3226 M)

Binary coded rotary DIPswitchesSpecificationsRatingsMechanical Life: 4000 cycles of operationminimum. Note: one cycle is a 360° rotation

actual size

and a return through all switch positions to thestarting point. 4000 cycles of operation isequivalent to 72000 position actuations.Make And Break Current Rating: 2000cycles of operation for the following voltagesand currents; 10 mA at 50 mVdc; 125 mA at30 Vdc.Contact Resistance: 100 milliohms maxi-mum after life measured at 10 mA DC and anopen circuit voltage of 50 mV_ 50 milliohmsmaximum initially.Insulation Resistance (At 100 Vdc): 1000megohms minimum after life. 5000 megohmsinitially.Dielectric Strength: 500 Vac between cur-rent carrying members.Current Carry Rating: 2 Amps with a max-imum contact temperature rise of 20°C.

Grayhill Inc561 Hillgrove AvePO Box 10373La GrangeIllinois 60525Telephone: (010 1 3121 354-1040Telex: 910-683-1E60 (3231 Fl

New range of ElectroproductsALFAC have introduced an updated pro-

. gramme of dry transfer Electro products whichare available for professional designers ofprinted circuit layouts as well as for amateurswishing to design and make PCBs on a one-offbasis.A free copy of the new ALFAC Electroniccatalogue is available, together with infor-mation on stockists, from

Pe//tech LimitedFREEPOSTMinerOxon OX8 6BRTelephone: 103931 72130:72014Telex: 83147 (via or pelltech of (3232 M)

Distance measuring sensorHoneywell have added another distancemeasuring sensor to its product range. Thenew inductive proximity sensor, Series 924, isdesigned to detect the approach of any metalobject and produce a linear output voltageproportional to its distance from the sensingface. Two sensing ranges are available:2_ . _5 mm and 4.5...9 mm. The sensor hasintegral signal processing and is not affectedby mechanical wear since it has no movingparts. It uses the ECKO (eddy current killed

oscillation) principle, and is continuously pro-tected against reverse polarity, overloading,and short circuit_

Honeywell Control Systems LtdHoneywell HouseCharles SquareBracknellBerks RG12 lEBTelephone: (0344) 424555Telex: 847064 (3233 F)

5-69

eiektor may 1985advertisement

REGULATORSLM 317T Plastic T0220 variable .. £ 1.00LM 317 Metal £ 2.207812 Metal 12v 1A £ 1.007805/ 12/ 15/24 plastic 50p7905/ 12/ 15/ 24 plastic 50pCA 3085 TO99 Variable regulator ... £ 1.00LM 723 14 dil 50p

EPIIOMS/MEPAORIES27128-300ns £ 12.002764 INTEL/FUJITSU 300ns 1 5.002716. 2708. 1702 ex eqpt. £2.002732 ex eqpt. E 2.502114 ex eqpt 60p 4116 ex eqpt. 70p4164-150ns new 3.70MC6810P E 1.00

POWER TRANSISTORSTIP 141, 142, 147 ea. £ 1.00TIP 112. 125, 42B 2 , £ 1.00TIP 35B _ £ 1.30 TIP 35C .. £ 1.50SE9302100 V10 ADarLsimTIP121 2/ 1.002N3055 Motorola 50 p 5/£2.002N3055 Ex eqpt. tested 4., £ 1.00Plastic 3055 or 2955 equiv. 50p 100'£30.002N3773 NPN 25A 160V .. 1E1.80 10 £16.00

DISPLAYSFutaba 4 digit clock fluorescent display5 -LT 16 £ 1.50Futaba 8 digit calculator fluorescentdisplay 9 CT -01-3L £ 1.50LCD Clock display 0.7" digits £ 3.00Large LCD Clock display 1" digits _ £ 3.007 seg 0.3" display comm. cathode ... 50p

QUARTZ HALOGEN LAMPSAI 216 24 . 150 £ 2.25H1 12 v 55 w (car spot) . £ 1.25

MISCELLANEOUSNEW BRITISH TELECOM ptug + lead £ 1.501.25" Panel fuseholders 5/£1.00STAINLESS STEEL HINGES 14.5" by 1"open each 11_00 10/17.00Mains transient Suppressors 245 V 3/£ 1.00TOK KEY SWITCH 2 POLE 3 KEYSideal for car/home alarms . £ 3 100/1 2.0012 v 1.2 w small wire ended lamps/fn Audi/VVV/TR7/Volvo/SAAB _ 10/£ 1.00Heat shrink sleeving pack £ 1.00PTFE sleeving pack asstd. colours £ 1.00250 mixed res. diodes, zeners £ 1.00Mixed electrolytic caps. 100/£ 2.00Stereo cassette deck £ 5.00 (1 1.25)Stereo case. RIP head £ 2.50Mono head .. £ 1.00 Erase head .. 50pThermal cut-out 50°. 77°C, 85°C, 120°C80pThermal fuse 121°C 240 v 15 A 5/£ 1.00VERO pins fit 0.1" Vero 200/£ 1.00Double sided PCB pins 200/£ 1.00T0220 Micas + bushes 10/50p

100/£ 2.00TO3 Micas + bushes 20/£ 1.00Relays 240 v AC coil PCB mounting2 pole changeover £ 7.003 pole changeover E 1.00Fig. 8 mains cassette leads 3/£ 1.00KYNAR wire wrapping wire2oz reel £ 1.00PTFE min. screened cable ... .. 10 rn/£ 1.00Tokin mains rfi filter 250 v 15 A 1 3.00IEC chassis plug/rfi filter 10 A £ 3.50Epoxy potting compound 500 g £ 2.00Mercury tilt switch small £ 7.00Min. rotary sNv.4p c/o 1/8" shaft 2/£ 1.00Thorn 9000 TV audio o/p stage 2/£ 1.0010M7 CERAMIC FILTER ... 50p 100/£ 206m or 9m CERAMIC FILTER

50p 100/1 25240 v AC FAN 4.6" SQUARENEW £ 5.50 (£ 1)240/115 v AC FAN 4.6" sq. NEWE 7.00 (1 1)

KLIPPON terminal block EKS 12/4 12 way20 A term block 3/£ 1.00

BELLING -LEE 12 way blockL1469 4/1 1.00POTENTIOMETERS short spindle2k5 10k Lin 5/£ 1.00500k lin 500k log long spindle 4/1 1.0040 kHz ULTRASONIC TRANSDUCERSex. eqpt. NO DATA pair £ 1.00Stick -on cabinet feet 30.1 1.00TO3 transistor covers 10:1 1.00transistor mounting pads T05/7018 £ 3 1KDIL Reed Relay 2 pole N/O contacts £1.00

RECTIFIERS120 v 35 A stud 50p12FR400 12 A 400 v small stud ... 4/£ 1.50BY 127 1200 v 1.2 A 10/£ 1.00BY 254 800 v 3 A 8/£1.00BY 255 1300 v 3 A 61£ 1.001 A 800 v bridge rectifier 4/1 1.006 A 100 v bridge 50p10 A 600 v bridge £ 1.5015 A 100 v bridge £ 1.5025 A 200 v bridge ea. £ 2.00 10/£ 18.0025 A 400 v bridge £ 2.50 10/£ 22.00

SCRSMCR72-6 400 v E 1.0035 A 600 v stud 1 2.0070 A 500 v large stud £ 3.00MCR106 equiv. 4 A 400 V 40p2N5061 800 mA 60 v TO92 4:1 1.00TICV 106D .8 A 400 v TO92

3/£ 1 100/1 15.00MEU21 Prog. unijunction 3. 1.00

ACSdiacs 25pTXAL225 8A 400V 5 mA gate 2. £1

100/£35.00TXAL228 8A 400V isol. tab

2/£1.00 100/135.0025A 400V ex eqpt. tested £1.50

CONNECTORS toe Earn Rios per pair]'D' 9 way £ 1 15 way £ 1.25 25 ,.vay £ 237 way £ 2 50 way £ 3.50 covers 50p ea.NEW 25way PCB skt 1.00D9 PCB PLUG 90 deg. £ 1.500.1" d/sided edge connector. 32 way,ideal ZX81/SPECTRUM £ 1.500.1" d/sided pcb plug 24 + 25 way 1.502 pole sub min. connectors ideal radio controlRS466/472/488/343 5 pairsi£ 2.00

IDC CONNECTORS25 way 'D' Plg/Skt 37 'D' PLUG ea. £ 2.0020 way socket (BBC user port) £ 1.0026 way socket (BBC printer) £ 1.5034 way socket (BBC disc drive) 2.0040 way socket £ 2.00MADE UP DISC DRIVE CABLES34 IDC to 34 way card edgesingle drive E 6 double drive 18

WIRE WOUND RESISTORSW21 or sim. 2.5 W10 of one value for 1.001RO, 2R0, 2R7, 3R9, 5R0. 10R, 12R, 15R.18R, 20R, 27R, 33R. 36R, 47R, 120R. 180R,200R, 330R. 390R, 470R, 560R. 680R, 820R.910R, 1K, 1K15, 11(2, 11(3, 1K5. 1K8, 2K7.3K3, 10KW22 or sim. 6 watt7 of one value for £ 1.001R5, 9R1, 10R, 12R. 20R, 33R. 51R, 56R,62R, 120R. 180, 270R, 390R, 560R. 620R. 1K,11(2, 2K2. 31(3, 31{9. 10KW23 or sim. 9 watt6 of one value for £ 1.00R22, IRO, 3R0. 6R8, 56R, 62R, 100R. 220R,270R, 390R, 680R, 1K. 1K8, 10K

KEYTRONICS332 LEY STREET, ILFORD, ESSEX IG1 4AF.

Shop open Mon -Sat 10am-2pmADD 15% VAT TO TOTALTELEPHONE: 01-553 1863

ELECTRONIC COMPONENTS BOUGHT FOR CASH

W24 or sim. 12 watt4 of one value for 1.00R50. 2R0. 10R, 18R, 47R, 68R, 75R, 82R,150R, 180R, 200R, 270R, 400R, 620R. 820R.1K.

PHOTO DEVICESSlotted opto-switch OPCOAOPB815 £ 1.302N5777 50p

100/1 26.00TIL81 TO18 Photo transistor E 1.00TIL38 Infra red LED 2/50pOP12252 Opto isolator 50pPhoto diode 50p 6/£ 2.00MEL12 (Photo darfington base n/c) .. 50pRPY58A LDR 50p ORP12 LDR 85pLEDs RED 3 mm or 5 mm 12/11.00

GREEN + YELLOW 3 or 5 mm

FLASHING RED 5 mm

100:'£ 6.0010, £ 1.00

100 '1 6.5050p 100/£ 30

DIODES1N41481S3740 Germanium1N4004 or SD4 1 A 300 V1N5401 3 A 100 VBA 157 1 A 400 VFast recoveryBA 159 1 A 1000 VFast recovery

MULTI TURN PRESETS10R, 20R, 100R. 200R, 50OR2K, 5K, 22K. 50K, 100K, 200K

IC SOCKETS

1001£ 1.50100/£ 2.00100'£ 3.0010/1 1.00

1001£ 2.50

100.£ 3.50

8 pin14 pin16 pin 12/1 1.0018/20 pin 7/£ 1.00

50p

12 £ 1.0010.E 1.00

100 1 6.00100 £ 12.001K/E 50.00

22/28 pin 25p24 pin .... 25p 100/£ 20.00 1K:£100.0040 pin 30p

TRIMMER CAPACITORS smallGREY 1.5-6.4 pFGREEN 2- 22 pF 5 for 50pGREY larger type 2-25 pF 5 for 50p

10A 250v ACzero voltage switchingcontrol voltage 8-28 V DC £ 2.50VARIAC 0 to 130 V 6 Anew uncased f 6.00 (121

POLYESTER/POLYCARB CAPS10n '15ni22n:33n 47n. 68n10 mm rad 100/£ 3.00ICOn 250 V radial10 mm 100/£ 31p5 P/carb 15 mm rad ... 100/1 7.00 (Cl)202 160 V rad 22 mm 100/E 70.00 (11.50)470n 250 V AC X rated rad ... 4'1 1.0033n/47n 250 V AC X rated rad 15 mm

10/£ 1.0010n 250 V AC X rated rad 10 mm10/1 1.00100n 600 V spragueaxial 10/£ 1.00 100/£ 6.00

BEAD THERMISTORSGLASS BEAD NTC Res 20'c 8Op250R. 1K2, 50K. 220K, 1M4R53 Thermistor £2.00

BEAD TANTALUM CAPS47 p 3 V, 68 p 6 V . 12.1 1.00 100, 6.002.2 20 V 8:£ 1.00 100,1 8.00

MONOLITHIC CERAMIC CAPS

100 n 50 V 100/13 470 n 50 V .... 100/ . 1 71.F 50 V 100/£ 810n 50V DIL package 0.3" rad.

100/14 lk/£30

MIN ORDER £2.50 OFFICIAL ORDERS WELCOMEUNIVERSITIES COLLEGES SCHOOLS GOVT DEPARTMENTS

P&P AS SHOWN IN BRACKETS (HEAVY ITEMS)65p OTHERWISE (LIGHT ITEMS)

5-70

athertisement eiektor may 1985

mkt& itatizi!E34. February 1978infra red Licht Gate.TnrowirtoSome L.-zhi on LEDs'Formant

ce E ).folic Synthesiserctl CMOS Function

__- 1-,,erTestenDeeeloisgs oerimenting with

838. June 1978GHz Counter/Constant Ans.

curse S.v-ewes* to Sew---nut - ...,ter :Servo Polarity

=,APolv Dice, Min.- Clock Using the .minable Call Gen-

. .=.1,.ind ModulatorL,:ieci Switch /Tref fie

ESA, October 1979Tcucn Tuning 8atterySaverilm-De2. Bridge/New Programsfc- SC-TAP/Digital Rot Chante:. ._ Snort -interval LightSe. _ "1_ '.Z7 Venable FuzzEly l'= -.;-es,iStran GaugedPi ay ea TV G3,,,es,Pra:yarr.nableSequencer£56. November 1979Tocump Flash Sequencer/Elec-tron.. the Easiest Way:Remote Control Motor SwitchHome Trainer;Fuel Economiser.I Played TV Games 121/Short-wave converter' ionosphere 'LowVoltage Dimmer See yourPointiSerm-controlled MO1Or.

E58. February 1980Aerial Booster/Fet Openps inthe Forman: TV InterferenceSuppression Elektor Vocaderl2IsAenal Amplitiers,Dig,SPlav/Analogue Delay Technology/Ex-tending the 1/4 GHz Counter.Dgital Thermometer.

E65, September 1980SK PP.,: 9 n 19K EPROMon 5t .-Power

O . _ CircuitEc t r 7.7 Multi-p_- - Scs,-. Readout forE'e-,mirtai .11 Box/Electro Tracer/Usino

Vocader.E66, October 1980Programmable Slide Ferder,TouChDoornelliSyeached Capacitors,More TV Garrift,The JuniorComouter Memory Card. RemoteControl Slide Projector -VideoPattern Generator. LCD TuningScale. Du al Slide Faders

E67, November 1980An nom. Indicator as anEco,c-ty GudeDraught Detec-t,. - Recycle Dry Cell

eigy SavingEconomy

_ .dmp Control-r e- our in Light

C Curtain Con.= age Alarm/Know the ins

of your Central Realm;

Svile'n'Ener3V Sir -:'g .ntorControl: Coffee Machine SwitchOperational Hours Counter

en

416410741104.

-.1- .41104.111m1k

Wit4-4.4

E68. December 1980Canned Circurs 23 of the Pestentries which MidnightRaid Detector A Plash in theCan' Conomere, Canine Gefence.E70, February 1981Audi') Power Meter -Noise Reduction . Process Timer Highvoltage from 723 JuniorsGrossing Uoi The VorcertLin-voiced Detector ErnemencyBrake for the Power Supply150W DC to DC Converter forrise Car.,Low Noise 2 MetrePre -Amp 2' Digit DV/J..1'41onechart_

E22.Awil 1981Transistor )date- r-sa! Passer . -mcIity Sensor .Lca.c A naviterCrystal -controlled StroboscopeJunior Cooktroot.

E73. May 1981cimp-ng CL -.L. Frequency2, . Fledged

- - - I, to corn.Bar Codes

_ i.eyses,rieseforrn Geri-5-7,-phisticarecl Software

for -the Junior CorrirriateriRead.rig Bar Codes.E77, September 1981OFM OVMIRevolution CoonieriDigital Barometer/dB Con-verter/TV Garrim. ExtendedDisco Lights ControtierOUADESL 631Analogue LED DisplayVolt/Ammeter for Power Sup-plies.Chattermg ChipsfTransistorIgnition UpdateiSaldering

E89, September 1982Gas Detector/Rapid LoadingGaines The Elektor Connection.inductive Sensor DarkroomComputer Pan 1 / Applikator,Home Telephone SysterniSynthesised Sound Animation/TimeReceiver for the Pitiable MSFThree Phase Tester.

£90. October 1982DS8 Demodulator/LC-0. Ther-mometer:Ultra Sonic DistanceMeasurementsElectrolyirce RimDry/Darkroom Computer Part2/Short blase Band Shifting forSSE Receiver/16 Channels withonly Five ICSPre-amp for theSSB Receiver / Active AerialTransistor and IC Dare£91, November 1982

xe!Taltong DiceLightina.Guitar

Tor t Floppy Disc Interiace the Junior/CubuLsr Bei, -.-Organ Extension'Kitchen 7,-.eE-93, January 1983Milliohmmeteriacessories forthe Crescendo power amplifier/Darkroom computer tips/Chipsfor digital arttio13 A computer

supply/Traffic-light control sys-tem / Tomorrow's music Upperand lower care on the Elektermina.

E94, February 1983Prelude part 1/VAM - video/audio modulator / Main beamdimmer/Prelude clan A head-phone amplifier/Fuse protector/Acoustic telephone modern/Double dice/Chips for digitalauto part 2.E96. April 1963Low power digital thermometer/MC/h1M phono prearnp/Membrave switches/interlude/RCequalizer/7-day timer/control-ler/Junior program teneriPre-lude load 311Prcgrammailedarkroom timer/Talking clocken tension

897, May 1983Wattmeter/ASCII keyboard/Pre-lude p.sfMultiletter/M2estrO/part 11/What is pcnvernParallel-serial keyboard converter/Morseconverter/78L voltage regulators- and 791 -Morse decoding Withthe ZBOA.

E99/100, July/August 1983Summer Circuits Double Issuecontaining over 100 projects.E101, September 1983Video Graphics I Autotest /64k on the 16k Dynamic RAMCard / highspeed CMOS / VDUCard Personal FM / PrecisionVoltage Divider / Alarm Exten-sion / Junior Synthesizer /Simp4 MOSFET Test.

£102. October 1983Basicode-2 1 Music Cluantisizer /Solid-state Darkroom Lighting /High -voltage Regutator / Anem-ometer Programmable PowerSupply . Easicocle-2 Interfacefor the Junior Computer / Elec-tronic Voltage Regulator / Bat-tery Eliminator TransistorSelector / FSKIeener EPROM -over using the Junior Computer_

E103, November 1983Doorbell - or telephone -Wasted flashliahL/Power Con -vast for Model Railways/Decouplirg in Digital Circuits,CPU Card/Decimal to BinaryConverter/Movement Detector/Electronic two-tone Metronome,Pseudo Stereo/Universal Ter-minellUhrasonici Infrared Bar-rier/Trick Battery/Crescendo re-visited.E104, December 198364 -way 2 -dimensional Bus Board/MF/HF USES Marine Reciver/LED OrnamentaSymmetncalPower SupplyiVideo Amplifier;Locomotive Headlamp Reverser/Frost Warning Device/DiscoPhaserl Banking Prograrn/N OV-RAM : Data Storage without Bat-teries/Bus Extension/ * Curnu!alive index 1993.

8105, January 1984Gyrophone/How aasurate isyour watch? /Digital CasetteRecorder/Audio Signal Embel-lisher/Universal Active Filter.'from Thermometer to Thermo-stat/Aucho Sleuth at work./WindDirection nthcator/Z80 EPROMreogrammeriHome-made lowcost Wiring Probe/Address de -ding.

E106, February 19846502 TraceriDiesel Tachometer/Programmable Disco DisplayLights/Vrdeo Combiner/Dagi-tester pith a difference/Revers-ing Buzzer/Memory timing/Meting Logic Fanilies/Cmaaci-:anCeMeteriBassoade 2 for Juniorplus VDU CadiC,onstarit Volt-age Source/CS Chip Selekt/Video Sync Box_

E107. March 1984Petrol Saver/Triac Control Beard/UHF Video and Audio Modu-lator! GET & GO/Elabyrinth/Var is -tor Protection Circuits/Real -Time Analyser (part 11lApplicator/Tape Timer.E108, April 1984Optical Memories Connor:1,i; TheFloppy -disk Drive MototPulteGenerator/Using the Pulse Gent,atorilnreiligent EPROM Eraser280 &rmiletorelitenonome Es ten-sion/Reeldirrse Analyser- part 2Variable A.0 Ptrobt Sum, Yheist:Chip Selekt/Tape ContentsDetector.

elektor -

electronics

&tad,-Wort-viirse porker radio

k= -p vaitchim-.2 sways- *applyrair crrscrtado

£109. May 1984Nora Scesach:Short-weve PocketRedio,Froppy Tener/Switchir;Passer SbOolVArialatiM1 VideoDisplay/Aviarymany Wetter/Mini Crescendo-_took at EXOR and EKNOR GattiEPROM Copier:Digitat CassetteRecorder revisited Raw -time Ana-lyser. part 3l RS423 interface.

EllCk June 1984PO/Tat:et D:stressS.grtaiZX Eten-sione,Ors..-o Druns,DaityydieelTypewriter Printer inserface, i-mum and Minimum heaSPO-N,lead -acid Battery OtagerWire-less Microononefireiging BASICProgram:0 Echo Sounder:VersatiletlJ di° Peak Meter.

E111/112.Juty/August 1984Summer Circuits Double IssuetrontarnIng Over 100 Prerebtt-

E113. September 1934Data Corrznunicabon by Tele.phonelActise cross -over Filer/Digital Cassette Recorder withthe ZXBURash Meta/DigitalTachometer/DIRPUT/SCARTAdapter/Anodizing Aluminium /Lamp Sayer/Doublesided Printed Circuit Boards.

E114 October 1984The Sinclair QL - feat impressionsIBasicode-2/Turing Fork/Balancing Transfourers/VideoColour In-sertertProgrammiOgthe 6845/ZX8I Cassette PulseCleaned/Depot-coupledModem +Battery Testa -RS232Centronics Converter/ DynamicPreamplifier

videocolourinverter -

015. November 1984The Story of Vahes'Autodirn/Mini Printer 'Burglar Deterrent/How to make your own PCBs/RS232 V24: the Signals/Useyour TV Receiver as a Mani.tar,' Telephae'VahefteriEcnoinic Gas Meter

E116, December 1984Electron CandleTlvo XR22C6in the Function Generator SttOrthan a BASIC/Function Genetate, --a Switch/CumulativeIn de. Mire.i-n1 Greeting

.e your Soldering Tip a- Computer -cannoned

SIfivez 7- -3=!.=,- Controller.'hl.-- . - Fre-

E117. January 1985Commodore Cassette Inter-face;/HPUHF Modulator/Fort-able Guitar AmpLflet/30 watta.f. Output Stage .15R snapRumble DetectovuP-controlledFrequency Meter. SnitchingRadio Control Channels.

E118, February 1985Gyroffash11.2 GHz InputStage'Microphone. PreampEfia,Remote Model Control tryMicrocomputer/DIY Connec-tor/Programmable RtrithmBox/EPROM Selects/ReceiverPower from Engine BatteneiRLCMeter; Programmable KeyboardEncode.

Back numbers of Elektor currently available are detailed above, with a brief description of their contents.Send for your copies now, using the pre -paid Order Card inside the back cover of this issue.Prices are as follows: any one issue (except July/August) £ 1.50

additional issues, each £ 1.30July/August (Summer Circuits) £ 3.00

Prices include postage and packing. Overseas orders requiring airmail postage add £ 1.50 per issue (£ 2.00 for July/Augustissue) (Prices subject to change without notice)

5-83

=rom a gentle purr to a mighty roar.he tightly controlled power of the

r.'east is yr:Aire to command!

I UV

,

i.:1it 1ilk!!!I firi g ill 1451 ki [17

A new range of superb quality loudspeakers.* Virtually indestructible high temperature

voice -coil reinforced with glass -fibre* 100% heat overload tolerance* Advanced technology magnet system* Rigid cast alloy chassis* Linen or Plastiflex elastomer surrounds* 5 -year guarantee (in addition to statutory rights)

Available in 5, 8, 10, 12, 15 and 18 inch models with 8t! and some 16!)impedances and with input powers ranging from 50W to 300W e.g.5in. 50W 95dB Bil: XG39N 16i1: XG40T £17.95§8in. 100W 98dB 811: XG43W £29.95§

10in. 100W 100dB 852: XG46A f.29.95§12in. 100W 101dB 80: XG49D E29.95§12in. Twin Cone 100W 100dB 811: XG50E 16(1: XG51F £31.95§'Llte- the c:it.%1 cic,:..bles for each 3dElincre-:":se (ref

A new range of very high quality multimeters offering Wily amazingquality at the price.

Pocket Multimeter. 16 ranges, 2000ILV DC AC £6.95§ (YJO6GiM-102BZ with Continuity buzzer, battery tester and 10A DC range. 23 ranges,20,00012N DC £14.95§ (YJO7H)M -2020S with Transistor. Diode & LED tester and 10A DC range. 27 ranges20,000111/ DC £19.95§(YJO8J)M -5050E Electronic Multimeter with very high impedance, FET input. 53ranges including peak -to -peak AC. centre -zero and 12A AC DC ranges£34.95§(YJO9K)M-5010 Digital Multimeter with 31 ranges including 20(1 and 20µA DC AC FSDranges, continuity buzzer, diode test. and gold-plated PCB for long-termreliability and consistent high accuracy (0 25% 4-1 d glt DCV) E42.50§ (YJ10L)

NE .7,- VAT and Carnage A 50p ha,: - cnargr= -ac = ES5 t s^S5onms'c =" -arab=

PAAPILIN ELECTRONIC SUPPLIES LTD.Mag Omer: P.O. Box 3. Repave. Essex S56 8LFL Tet Southend (0702) 55291'SHOPS

BIRMINGHAM Lyman Square. Puny Barr. Tel: 021-356 7292_ LONDON 159-161 King Street. Hem7s-smit. W6. Tett 01 -7480926. MANCHESTER 8 Oxford Road. Te; ' -2380281.

SOUTHAMPTON 46-48 Bevois Va' e, :ad. Tel: 0703 25831. SOUTHEND 282-284 London Rd. V. F 'f -on -Sea. FccPx. Tel: 0702-55400:

&se: a :Ey

nlaDANT-))

/I 4 t

Our huge range of top quality electronic components al very competitiveprices are all detailed in our catalogue. and ivith well over 600 new linesin our 1985 edition and many design improvements. it's well worthgetting a copy. Here are just a few examples from the catalogue.(The items below are NOT kits).* Most phono and jack plugs now with integral strain relief sleeve - gold-plateatypes also available from 14p (gold from 70p)* Stereo Disco Mixer with cross -fade. talk -over. cue monitoring. aux incs'C Eq 95 fAi=g9H,

* 10 -Channel Stereo Graphic Equalisers - 3 models - basic: with peak levelrrieter: and with spectrum analyser - from £77.95

* 0 * . ID -- _ _ _

* Digital Delay Line permits Slap -back. Doubling, Flanging, Chorus and Echo11 controls. Only £195.00 (AF98G)* Video -Enhancer improves picture quality when recording from one VTR toanother, and with TV's with monitor input. Only 28.95 (XG59P)* Detailed descriptions of the exciting new 74HC range of ICs whiCh combinethe advantages of CMOS and TTL. From 46p -* Keyboards: sloping keys, two-tone grey, mounted in steel frame, very smartcases (extra) available. 61 keys, only £33.95 (YJ12N)

79 keys, only £37.95 (YJ13P)* 1% Resistors now 50ppm'C, 0.4W, only 2p each!* Auto transformers 120 240V 50VA, £10.75§ (YJ56L). 100VA £14.95§(YJ57M). 150VA £16.95§ (YJ58N). 250VA £21.95§ (YJ5913).* Digital Clinical Thermometer_ Only £13.95 (FK51F)

1 r , i i 11 i i 11 . i .1 . ..;) ,' i \ ' ' MraPILin\

'-'-' '. '.,'1')-) .1..1..,i.,;___, .1..,

1.1d

...-11 , ,_._,...-..',

.e..'1 . 1 1. .1 ..) 1 ..i I 1 ) li )k 1

Check our 1985 Cataloguefor all our other fascinating :new lines.

T.3 Phone before 2pm forsame day despatch.

9.185CATALOGUE

Pick up a copy now at any branch of W.H.Smith or in one of our shops. The price isstill just £1.35. or £1.75 by post from ourRayleigh address (quote CAO2C).

Post this coupon now for your copy of the 1985 catalogue.Price £1.35 - 40p post and packing. If you live outside the U.K.send £2.40 or 11 International Reply Coupons. I enclose 75

Name

Address

Indicates that a lower price is available in our shops. All offers subject to availability. Prices firm until Aug. 70th 1985