CHROMATHEQUE 50005 CHANNEL LIGHTING EFFECTS SYSTEM
r,4c
4"" 4/1PLETEZITON..lb
£49, .616 + VAT!
A 100
cp.NO.
cvb
MP sint444<mixtemveinvb*"
CryiPLETE KIT-r16 .8=1i -it. MX .0.: : 0: :ik:
MEW 0 0 7 -tor. O+ VAT0
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es, caps. E1 .60 o wit Jot, El 0.54,0 Ai reap
R A Pitt E VOCOrtSI LEtatIOD04YNtHESIZER
COMPLETE KITONLY
£172.00 + VAT!
PONIRTRAN
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TRANSCENDENT 2000 POWIRTM
ORDERING INFORMATIONAND MORE KITS ON PAGE 8
Boats Crossroads . ,327
electronics todayAPRIL 1979 VOt 8 NO 0 INTERNATIONAL
FEATURES
NEWS DIGEST 9 Did you knoyPOWER ...MVP/ 19 Power .0. PeOPIe
Grn REVS.ED 37 New Me foi an okl ideaDATA SHEET 52 IC swyey
READERS DESIGNS 54 Vow deSignE buthTEN 3080 CIRCUITS 70 It does more than you think
MICROFILE 80 A floppy petTECH TIPS 103 CitYuits from you to you
PROJECTSVIDEOGRAPH 27 Sound to fight on your telly
CLICK ELIMINATOR 41 Clean up your recordsAMBUSH 61 The new spa. game with a.m.
WIND SPEED INDICATOR 85 Gel the wind up this unitGUITAR EFFECTS UNIT 97 We think we've found a new one for you
PCB FOIL PATTERNS 110 All in one pia. now
INFORMATIONBOOK SERVICE 25 von name o we have a book on it
HOBBY ELECTRONICS PREVIEW 35 On as way to y.ETi PRINTS 49 or DIY PCB a
MARKET PLACE 58 Can von n.nne$. prices,ETI SPECIALS 69 Specially for you
COMPUTING 0000 83 On its own nowNEXT MONTH iry 90 What we ve got for May
25 27 Oxford Street 71117AVIrTVeTprgrOEINUr41 2 Tele 8811898
Mayby. Ian ...re 8
Teennly. IllustratorsVey Menton Vv.. Ed.,
Ste,,:re:riny?:at Pm, Development
Iterna7-=
Smt12":"*IYa=lt27-1=AdveMs.Y
ELECTRONICS TODAY INTERNATIONAL - APR, 1B/B
BOOKSBOOKS BY SABAN!
...
AND COMPONENTTRANSFORMERS
. .. . . ..,
SWITCHES
AUDIO LEADS
. ..
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FUSE HOLDERS ..-. AND FUSES..,,._, .....,...
::BOOKS BE NEWNES ,.......-IT"
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-°g ir ,1.33 ,,F
II
:2 ....-NUTS AND BOLTS
,..
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ANTALUIS CAPACITORS
NEATSINNS
SI
. ..,
ELEC, NIPS TODAY INTERNATIONAL - APRIL 197
SEMICONDUCTORSTRANSISTOR 74 SERIES TTL ICs
' 1
CMOS ICs
11 B13 H' 1L 11 11
1111
LINEAR ICs
'47', 3 I- 4,113 111.7
DIODES
!!!!
1 -PAN
QUARTZ LCDALARM 7 Function
£19 65
M5
HANIMEXElectronicLED Alarm Clock
£8.65
M13
QUARTZ LCD AlarmChronograph psi. DualTime Zone Facility
£27.65 MB
QUARTZ LCD AlarmChrono oillM1 front alarm
£29.65
QUARTZ LCDLadies B Function
M15
QUARTZ LCDALARM 6 Function
E16.65
M4
SOLAR QUARTZ LCD5 Function
9.95
MI2
1717fteC ELECTRONICS& TIME CENTRES
ELECTRONICS TODAY INTEPNATIoNAL -AP,1979
DIGITALCLOCK RADIO
.11g
019.95. .,
M17
DIGITAL CLOCKRADIO Portable LCD
DIGITAL CLOCK LCDTr.., --- -
coot,
,,,,
Digital Clock/Alarm/Calculator/Stopwatch
A0.1000
021.85 M20£19.95
M18765RADIO/CASSETTE4.13ancl/LIN-MW.SW.FIVI
RADIO/CASSETTE3-Bancl/LIN.MW-FM--,
£34.95
RADIO/CASSETTE2.13and/LWEEW
E29 95
RADIO/CASSETTE1-Band/MW
017 95M24
. .....
(38.95 M21M22TV GAMES
Atiltq1k.a
E13.95 ColourL5.95 BM' .26
TV GAME WITH GUN,
MAINS/DATTERVPortable Radio
AIRCRAFT RADIO
f9.95028
'k " 4.'/a.I tk
£19 95
M26
..:':.f19.135-'-'.-, M27
RESISTANCEDECADE UNIT(Exc.. to Mewl
S'
. .... i ........
(29.95
1029
METAL DETECTORc
Fn187'r
SHARP GE -1603MQuality Radio/Cassel
CAPACITANCEDECADE UNIT(Exclusive to Maud
.0
r 29 95
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£25.95
I
10....I
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ril M =tv.=W:.
CrliONICS TODAY INTERNATIONAL APPEL 1979
POWERTRANPS10002 STUDIO MODEL
FOR ELECTRONIC KITS OF DISTINCTION
COMPLETE KIT ONLY E1913.90 + VAT
READ THE REVIEWIN SOUND INTERNATIONAL DEC. 711
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21111+2110 watt AMPlifIfil400VV rms continuous - 800VV peak!003% TH 0 at FULL power!PLUS all the following features too!
WIRELESS WORLD EPA TUNER ENE 20 4. VAT
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POWERTRAN ELECTRONICS
. APRIL 197
rMIC110 CNimEsFROM THE INVENTORSOF MICROPROCESSOR
MUSICAL CHIMESNew price for the fioriginal
t-CHROMA-CHIME KIT24 tune model!
CuN the fantasticSuccess el the Prod .across Me World we are aMble to offer itat
Only £9.95 + MP IMPCornesCorriplete. POSOOOMerp Feihneepareiregg
Superticalainet Pa semponductorg
_r fulrydelaenenma.ual
TAAS 1000N -M111.002iA Microcomputer ch. available separaIefyreguded 24 tune spec devicesupplied.. data sheet and lull,guaranteed
New low price only £4.95 Inc.pap
A COMPLETE KIT FOR THE
NEW MICROCHIMEThis eas
OlIncludesMISIODOCuslom MPU ChinSoeco, Purpose cies,. casePretv drilled and mgenaed PCBMI transistors RehalOrs endCapacitors
n Full Wel mechanical gagsSrnan leave labelsIC SOCFelanOLOWspeaNerReally Low lance.
poly £8.95 + PSO pap
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.-_61;11101TIATF10111C:RONICS INTERNATIONAL - APRIL 1979
newsdigestOOMPH -UP n
OOPS AND ALL THAT ...1,1sco Lightshow - Dec
"r1
ra!ilgee"
Stage Dimmer March
STEVENSON imomas 7'sElectronic Components
SWITCHES
POTENTIOMETERS
KNOBS
MICROPROCESSORS
REGULATORS
THYRISTORS AND TRIACS
:gatatztoMad orders to STEVENSON IIloot ET,
236 High St, Bromley, Kent, BR11PO, England
news digestINFRARED EYES
ESE RAILWAY HOUSE, HARDHANI CROSSING. HOWL/ROUGH, SUSSEX
ELLC7RON. TODAY INTERNATIONAL - APRIL 1979
INTRODUCINGDUAL DRIVE MINIFLOPPY FOR PET!
INTERNAL MEMORYEXPANSION FOR PET!EXPANDAPEr
. VAT INV
7r.P;:YV:71.7:7:?ZP=.=LIM per sea. Int. PAP
OHIO SCIENTIFICSUPERBOARD II
MI plus VAT
LOTUS SOUND, 4 MORGAN ST., LONDON E3 ASTel' 01-9613993 Telex 261026 Ann ,r
INTERNATIONAL -APRA I LA
NON -SUBSCRIBERSSTART HERE
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LECTRONICS TODAY INTERNATIONAL - APRIL 1979
AUDIO ANDTEST EQUIPMENT
CENTRE
LONDON S TEST GEAROPEN 6 DAYS A WEEK
5,^1- N srOCK MCP P t? 50 ea I
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FEATURE
POWER AMPSURVEYThe Americans would describe it as a 'crowded marketplace'. Power amplifiers appearalmost daily and the resulting choice can easily lead to confusion. Ron Harris attemptsall overview.
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Pts:nro rotngat 't'lla*p'reectr''A mlwah, ertlY a, 9, 'Oh deur,. we hhe , Proceed wth
what we have a ....der the two ampt I ars wh chd darr vela. the one on km
Our source for the I sten tests vas to he a SonyEL Elcaset machine wh ch gives reel to reel quaity of
ro.1=1.m"="yterrr'y 7anrCh7p=a1Odereo of equ pment such lona ous convenience is not
. scorned lightly
geh:tr'itne:rrirdS'o'n'atne's'cr'n't'"Inr gr:Standa d of ep L., L far above 7riatC."vg c'h anyCassette »ach ne ech eves
T. rale ence arnpl e was a Lamson AP3 I
AL -120 BI -PAX
OriZZOT4'.::eg«Itte:rolheats a. are hard wir. into the °amyl
The qua, ol construct,. was peewee), h Oh and muse Me ALI20s hare ra no trouble al all They drove therequired speakers Celest on KEF) reth nO apparentdress a. gave a see. )eehe ee, eeeeee) deem
Grimm CBIOSThere a not really a lot to say about Cr mson Elecir k thathes not .01 sa 0 a ready The r products aro wel
ierzl:nrr,gt out end well Mought orY The
Cr 'neon supp ad us the un complete y essemb ed
.Zdh4 l'I':.:ere'PrEr117rsOr:OT leee'egrrsdr?trOf
th'i'en'etrn.,74dkd black and ilstyle looks not unl ke aeos un
ILP NT50S nce these are completely encapsulated we can offer no
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FEATURE:Power Amps
TTI-A1616MTIIOT electronics truPs',2MZVOIT1111:7110"31111",nne,.ton th werb .ern TELEPHONE:01-W 370S
LOW POWER SCH0r11, and TTL CMOS BITS and PIECES
=
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ELEMIONICS 700a71,17EMPTIONAL - PPP, 1879
The latest kitinnovation!from
the quickest finingCLIP ON -capacitive dischargeelectronic ignitionin KIT FORM Smoother running // Instant alLaseaMor starting Coma:nal peak performance L y5,5il/battery /DMP .MS Irnproma accelaratioMtop speed OPSIIIIiIm fuel consumistiOn
BLOW THE af:F=Lne SOLD nipNASCOM I COMPUTER
1"1411;:12VATTACI:"E165 KITS IN STOCK:
BRITISH DESIGN.. HST SO...11
EXPANSION
SUPER -STRIPTHE UNIVERSAL BREADBOARD
Super Step SS,
LEKTROKIT LTD
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E ECIRIONICSTODAM1NTERNALIONAL - APRIL 1,79
ELECTRETAFOR A 0000 DEAL BETTER THAN MOST
ntett!IITT9=1.:,==ar
TWO DEPOTS TO SERVE YOU NOPTIII AND BOUT
ELECTRO I-VU LTD
PLEASE MENTION ETI
WHEN REPLYING
TO ADVERTS
-A Wilmslow-111 AudioTHE firm for speakers!
EyiFatt.::,":71Z
. .*. .
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WILMSLOW AUDIO Dept. ETI
PROJECT
VIDEOGRAPHTurn your colour television into a dual trace oscilloscope withthis UlIF colour modulator and video display generator.
Principle Of Operation
h line end a fixed.lengthhr4ght-up pulse
a twin trace. nd theSe
Zpectiwely 'U"rut::"triggered by a c pulse
generator. and .1 unher oemponents,enerate an eighaga Packg.andcolour change.
rcrer's7:17stZ"tape -recorders
Central, are provided for inven,^9
nd colour and swoching a
from William Stuart Systarn. Ltdwho Ned ie. PCB COPWng,,,at. produce a ready .11H/calomelThe heaw gauge anochsed facia plate
'"nkr;inatTdrs=entha id"..n
Constructionorcult board assemblies
Colour Modul:=Zrgege:
27
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OJE
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NC
LI
F
evz
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IELD
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H T
O IN
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IT)
OH
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1. U
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our
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ulat
or c
ircui
t dia
gram
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RK
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scill
ator
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erat
ing
the
prec
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o 44
3361
8 M
Hz
sulic
arne
r fo
r co
lour
info
rmat
ion.
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tran
sfor
mer
pro
duce
s ou
t.N
. whi
ch a
ro s
uita
bly
phes
e-sh
ifted
by
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II an
d R
23. D
iode
s D
I and
136
mod
ulat
e th
ree
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als
whi
ch a
re n
ow a
t+
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45 a
nd 1
80 d
egre
es r
espe
ctiv
ely
Col
our
hue
is d
epen
dent
on
the
sulic
urne
rph
ase
and
iii th
e P
AI.
syst
em M
O d
egre
esgi
ves
blue
whi
le&
- 45
deg
rees
ppat
hi r
ed a
nd g
reen
alte
rnat
ely
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e th
ree
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I bei
ng th
e co
ntro
ller.
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gene
rate
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quar
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e A
tha
lf lin
efr
eque
ncy,
and
this
is a
lso
used
to g
ener
ate
cohn
ir bu
rsts
via
C.2
2 an
d C
21. Q
2 am
plifi
es,th
e co
lour
info
rmat
ion
and
feed
s it
in to
join
mai
n V
ideo
grap
h D
ispl
ay G
ener
ator
.B
oth
are
prin
ted
with
det
aile
dle
gend
s so
that
com
pone
nts
can
bein
sert
ed d
irect
from
the
part
s lis
t.N
ote
that
eac
h bo
ard
has
a se
para
telis
t! The
ICs
shou
ld b
e in
sert
ed la
st o
fal
l, an
d IC
7 on
the
gene
rato
r bo
ard
shou
ld b
e le
ft ou
t ini
tially
: ins
tead
inse
rt a
link
bet
wee
n pi
ns 3
& 1
2 as
show
n. T
his
give
s a
fixed
gre
enba
ckgr
ound
and
res
ults
in e
asie
rse
tting
up
and
tuni
ng. I
C7
can
bein
sert
ed la
ter
on to
giv
e th
eau
tom
atic
col
our
chan
ge.
The
boa
rds
are
conn
ecte
d to
eac
hot
her
by s
hort
leng
ths
of w
irebe
twee
n th
e po
ints
labe
lled
OV
,F
ield
. +ye
, Vid
eo, 1
3,R
,G,X
and
Syn
c. All
the
cont
rols
can
be
boar
dm
ount
ed a
nd th
e on
ly o
ther
wire
sne
eded
are
for
conn
ectio
n to
the
aeria
l and
DIN
soc
kets
, and
9 v
olt
pow
er.
The
aer
ial s
ocke
t can
be
conn
ecte
d di
rect
ly to
the
mod
ulat
orvi
a tw
o cl
osed
loop
, one
on
the
boar
d an
d on
e on
the
sock
et. T
helo
ops
are
sim
ply
bent
to c
oupl
ecl
osel
y w
ith e
ach
othe
r. T
his
met
hod
the
blac
k an
d w
hite
com
posi
te v
ideo
sig
nal.
The
com
plet
e si
gnal
now
mod
ulat
es Q
3,w
hich
is a
VH
F o
scill
ator
. Har
mon
ies
in M
e01
4F b
and
are
extr
acte
d vi
a C
S a
nd d
ee,.
lope
d ac
ross
a s
hod
leng
th o
f prin
ted
circ
uit
Iran
i...M
inio
n lin
e w
hich
act
s as
a h
igh
pass
filte
r. C20
and
R2I
exp
and
the
Syn
c pu
lse
to g
ive,
cia
IC2
and
IC3.
the
Fie
ld s
igna
lT
his
isti
prop
erly
bla
nked
"ba
ckgr
ound
true
" fo
rco
ntro
lling
bac
kgro
und
illum
inat
ion
FIF
I.1/
,Ian
150
torc
ed lo
w if
the
'X' i
nput
is p
ulle
dhi
gh.T
hk fe
atur
e al
low
sobj
ems
whi
ch a
rs, t
obe
dis
play
ed (
e.g.
ther
e
Vid
eogr
aph
strip
es, t
oca
ncel
the
back
grou
nd w
hene
vthe
y or
e 10
ensu
res
that
no
"ear
th lo
op''
can
exis
t bet
wee
n th
e T
V a
nd th
e hi
-fi
syst
em, c
ausi
ng u
ndes
irabl
e hu
m o
nso
me
equi
pmen
t.
Set
ting
up
The
mod
ulat
or tu
ning
cap
acito
r is
set
to 3
0% o
f max
imum
. Gen
erat
orbo
ard
pres
ets
are
set f
ully
antic
lock
wis
e. T
he G
AIN
con
trol
ssh
ould
be
at m
inim
um a
nd th
eLO
CA
TE
con
trol
s at
mid
pos
ition
.C
onne
ct a
TV
set
via
low
-lo
ss c
oax
cabl
e an
d sw
itch
on b
oth
TV
and
Vid
eogr
aph.
Tun
e th
e T
V to
obt
ain
a go
od s
igna
l, se
arch
ing
from
chan
nel 2
1 up
war
ds. T
he p
ictu
rew
ill b
e un
stab
le.
Adj
ust R
V9
(Lin
e sy
nc)
to g
ive
anun
brok
en b
ackg
roun
d, a
nd a
djus
tR
V7
(fra
me
sync
) to
giv
e ve
rtic
alst
abili
ty. P
rovi
ded
that
the
TV
tuni
ngis
exa
ct th
e pi
ctur
e sh
ould
now
be
unifo
rmly
gre
en. I
f the
top
of th
epi
ctur
e is
red
then
adj
ust R
VB
(fra
me
puls
e w
idth
) fo
r be
stpo
sitio
n.A
djus
t RV
2 en
d R
V5
to g
ive
blue
and
oran
ge v
edic
al s
trip
es: t
hese
shou
ld a
ppea
r fr
om th
e le
ft as
the
I.
Inkg
;:rea
W7e
, iN
Mgr
Ale
fga
-rId
4,4
____
_
_
-s61
y
la-
Fig
. 2 C
olou
r m
odul
ator
com
pone
nt o
verla
y.
PA
RT
S U
ST
-M
OD
ULA
TO
RR
ES
IST
OR
S a
ll U
MR
I6k
802
.4,1
021
12
R3
1508
R5.
11.2
5-27
4/O
R86
.23
24 3
022
0887
.12.
15.1
611
1
Re
13 1
4 17
.18
.22.
2810
4t0
00R
19.2
033
0kR
21,
R29
.31
22k
68k
CA
PA
CIT
OR
SC
1.5
C6
C7 C8
10n
poly
este
r2-
22p
1.11
1111
1I,
2p c
eram
ic8p
2 ce
ram
ic
C9.
19.2
0.23
120p
C1C
IO1.
1218
039
p pc
eram
ic
Cf3
880p
C14
330p
C15
68p
cera
mic
C18
22p
cera
stm
icC
2I.2
2I n
pol
yeer
C17
.18
omitt
ed P
ox te
xt)
SE
MIC
ON
DU
CT
OR
S01
BF
197
02.3
BC
108.
BC
452
D1
-D9
1N41
48N
ote
DI .
02 0
3-04
. D5
-D6
mar
ched
pai
rsIC
I40
018
IC2.
340
078
MIS
CE
LLA
NE
OU
SP
C13
10 p
enee
n, b
atte
ry d
ips
VH
F s
ocke
t
PRO
JEC
T: V
ideo
grap
h
Fig
. 3 1
/ideo
grap
h ge
nera
tor
circ
uit d
iagr
am
A ty
pica
l Vitl
eogr
aph
telly
pic
tum
Fig
. 5 G
ener
atin
g gr
aphi
cs w
ith th
e V
itlea
grap
h.
HO
W IT
WO
RK
S -
GE
NE
RA
TO
R
1(71
and
IC2
are
timer
s w
hich
gen
erat
efr
ame
and
line
sync
res
peC
tivel
y. 1
C3
coin
.bl
ocs
thes
e to
form
neg
allv
e S
YN
C a
ndpo
sitiv
e sy
nc T
. The
leng
th o
f the
fram
esy
nc p
ulse
I.ad
just
ed b
y te
st Il
iis is
nece
ssar
yIn
in th
e P
AI.
syst
em th
ere
mos
t be
an e
ven
num
ber
of w
hole
line
perio
ds In
a fr
ame
puls
e m
riocl
, oth
erw
ise
the
Ti'
sees
dei
..ode
r w
ill b
e ou
t of s
tep
at th
ean
of e
ach
pict
ure
scan
and
the
top
of th
esc
reen
will
tend
to b
e re
d `g
reen
rev
erse
d.A
udio
inpu
t sig
nals
for
the
right
han
dch
anne
l are
nor
mal
ly fe
d to
142
alte
rn.
ativ
ely,
if th
e "r
ight
Inve
rt"
switc
h is
oper
ated
, the
n si
gnal
s pa
ss te
nt th
roug
h Q
l.
Q2
driv
es :I
cla
mp
diod
e 1.
31vi
a C
h R
V2
(pre
set)
det
erni
ines
the
mea
n 1)
C v
olta
gew
hile
RV
3 (L
OC
AT
E c
ontr
ol)
glee
s a
fine
adju
stm
ent.
Gat
esI
tria
l 2 o
f IC
4 R
um a
mon
osta
ble
trig
gere
d by
pos
itive
syn
c pu
lse
Thu
s. th
esta
tt °t
each
line
the
outp
ut o
ffe
edba
ck lo
w. a
nd C
O p
rovi
des
posi
tive
pic!
. but
is c
lam
ped
Le a
n in
itial
valu
e of
say
3V
by
the
clam
p di
ode.
C9
now
char
ges
via
R9
until
gat
e I s
witc
hes
back
(et
appr
osam
attiy
4V
)and
the
mon
osta
ble
rese
tsits
eR N
ote
that
the
char
ging
is n
early
line
arov
er th
e ra
nge
3 to
4V
and
R9
can
be c
onsi
d.er
ed a
s a
cons
tant
cur
rent
sou
rce.
Sin
ce th
ein
itial
cla
mp
volta
ge is
mod
ulat
ed b
y th
e
udio
sig
nal.
the
nion
nsta
ble
perio
d q
also
linea
rly m
odul
ated
.A
t the
end
of t
he a
bove
per
iod
a se
cond
.fix
ed d
urat
ion
nnirc
ntab
le fo
rnm
d by
gat
es 3
and
4 is
trig
gere
d vi
a C
I I. T
his
prod
uces
pSiti
VP
pul
se w
hich
def
ines
the
osci
llosc
ope
trac
e. Q
4 is
an
emitt
er fo
llow
er w
hich
driv
esth
e M
odul
ator
with
Vid
eo (
brig
htne
ss)
and
colo
ur in
form
atuo
n. a
nd s
uppr
esse
s th
eha
ckgr
ound
by
pulli
ng 'X
' hig
h. L
ine
and
Fie
ld b
lank
ing
are
ensu
red
by R
I4, (
'13,
RII
and
C7
whi
ch e
xpan
d th
e lin
e an
d fr
ame
puls
es a
nd p
reve
nt tr
ace
gene
ratio
n w
hen
netv
sser
yT
he li
ft ha
nd c
hann
el is
iden
tical
, exc
ept
that
the
outp
ut d
rive
is to
a d
iffer
ent c
olou
r,an
d th
e im
ener
sta k
igna
gy is
ab,
ent.
QU
det
ects
pea
sls
(nn
Inc
right
han
dch
anne
l) pi
oyi
ded
thaz
,LO
UR
HO
LD b
asno
t bee
n se
le,te
dhy
se s
iana
l, m
e sa
mpl
edby
the
tram
, ..y
nc p
ulse
to m
oduc
era
nU o
m c
lock
oul
ve lo
t cw
t., IC
I,IC
gate
s th
ree
Cl t
he c
ount
er m
amas
with
the
trim
. sig
nal a
nd d
rivrs
the
Mod
ulat
orw
ith b
right
ness
(V
ideo
) an
d co
lour
Ito
b)st
ICS
is c
onne
cted
as
the
squa
re w
ave
gene
rato
r. p
hase
-lo
cked
to th
e pi
ctur
e sc
anby
the
nega
tive
fram
e sy
nc p
ulse
FS
.
Fin
. 4 T
win
cha
nnel
Vid
eogr
apM
1 au
dio
driv
er c
ircui
t.
SLUE
BEE
rite
SOUARE WAVE
ig. 6 Videograpb generator component overlay
Circuit boards completed andinWalled in the \Odeon,. chassis
No. its not something from outer space,
BUYLINESA complete kit of parts is availablefor this project from William StuartSystems Ltd, Dower House.Herongate. Brentwood, EssexCM 13 350. The PCBs remain theircopyright and will be available onlyfrom them. All components areavailable separately, and the PCBsare normally supplied as a "mini.kit' along with ICI -3 and readywound coils. See advert elsewherein this issue for prices.
pots are turned clockwise. Positionboth stripes centrally. then separatethem using the LOCATE controls. Atthis stage the line sync IFIV9) shouldbe fine.adjusted to give perfectcolour registration on the stripes.
IC7 may now be inserted (and thelink removed.) to give thebackground colour change function:the sequence being black, white,cyan. yellow, green. mauve, blue,red. ET
32 ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
PROJECT: Videograph
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ELECTRONICS TODAY INTERNATIONAL APRIL 197
FEATURE
Gm REVISITEDNothing to do with American car manufacturers Gm is in fact a throw -hack from the days of valves, now finding a new lease of life with up-to-date semiconductor devices. K. T. Wilson explains ....
Correct Generators
ELK-M.1[510D., tt-rEit tt,irttc, tot 1,,
not
d aoue wee C011ector and minertha, uStstor An equivalentcomponentS which
of way aS SOnte deviee
Ftg 2 li conStStS 0 aand .1
ro'neosk InT,Z,:n ".: - ao.ntne .oclne Stae et ',tea,. cur Zc::::=Vand Ina output restsi
Hoe sloes Ces nalp uall the I tme that en tve e
-seen se cometnea Os peeve sumer So. eseeSneF cel as sac se as ins earth line
owet supply there s a sm
for ACing the
load
tpritit ate COnCetnect theonnecled between collector and emitter
nto the aunts! nICIF.11. and the result IS Ftp3 ears e teroldress el seises Mose, corner OesCes 'coed es sere e, loss erc eeeoe e erne,
"''' iliRdEtE;1Simple Silicon
?iF11°.!.=s.'sntrs"::07'71:ttrVtftl:li;e'g:doa:I'm°::
=.'s=c'e'111=1=17i:ZITtn' lAonl°401r:'tnr:Irt rtne's1=leclk;!er*I'l '1%*: Vantldor
Vrl'olrestZ.=':C:178:elo=s7on'th:7hetqaTiZIa tra.s.sior amplifier iS 'oat GmR
11 il s as easy aS that why dOn 1 we see ,t Mai 1reM tYEIM
,on tran,siorA u nan,sto. forget a Im ol Me old 1 ormulae we once uSed in Calcudoesn hay. a constant yetue of On. ri " o..apt. rating the design al transistor amnhtiers The fact Mat
Gm is not conStant but vanes with the bias current ts
tr-Zevott
Os MieVer-atiVleediibeGAIXMOlood
Vleact ISTIIE STEADY MIAS,VOLTAGE ACROSS
Ebert Moll
A lew yea, hack though the Baer: Molt eq.ration was...teed You Ye never hmrd Vou nOt atone
eapia.n., Very briefly s an equation whiahImIcs the collector cnneni won the Vhe yalu%for a
'er'rnr :1'.otrergL"is'aVsnour=g tit?:,utt a, mathematreat sr.., You ma,' "'.. W."tre1we It repays close aliennon theogh OMaose most
'c'onTr.an't"Xg'Iwo'XinnetrnTarh:er:'7nu'cr6n7c:1them .S Ine Steady ems current IC a. the othet ist'^EMMt.re . hed.ons ternOere,". 'or the Ournoses ol the Elam Moll equation .$ rneaSured in the
around - 273 C Room tennOerahne7-erotOre around 2g3K In0 Pewees sign, the Kelvin
Gain
!urge outPut resis'an0".'"0
woe.° piaceol Gmllig 41 This makes thegamol
equa1ion is Ihe steady bias collector current a.SO 100 must De the steads OC voltage across rel. theload resistor Thts mak. selculattno the gon of pens..tor ampltf ter. with resteive was iNt new than fal/ingoll a log Pock value of volmge across theltaad testator
OV 40 and Ma, S OmMinn example we very ol ton design voltage amplilierS
sothal about 01thesuppre settage 00"MP. MtOM
arm you can eanect a voltage gain ol 40 ea 5=180trmes 010, helmee lt arm. elt Pg. amMests oa a
VOu don t or course expect to get a garn exact, ' 80
on load ,PS.S10., apart hOm anythum etSe but you re
anoMer stage of course Mai s another story You mayhave sel the gain ot Me first stage to 180 limes hut notB1101.16 oupui Signal en. uO usefully at the inpul of the
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
FEATURE:GM Revisited
Fig. 5. Calculatinghow much signal ispassed on to sub-sequent stages.
L
r(Ittk=,
next stage. Reason? The next stage has a rather lowinput resistance, and feeding signal from the collector ofone transistor into the base of another, even if they aredirectly connected, is rather like feeding signal through avoltage divider. There are, in fact, two ways of calcu-lating how much of the signal is passed on. One simpleway is to imagine a voltage divider (Fig 5) in which theload resistance of the first stage forms the upper resistorand the input resistance hie of the second stage. Thequantity h,, (on k ohms) is equal to h)))/G in, where h1, isthe current gain of the transistor, a quantity which doesvary between one transistor and another. For a transistorwithlh,-= 100, Gm set to 40 ft mA collector current) h.. is100 /40= 2 k5. If we feed this from a transistor with a4k7 load resistor. the amount of signal reaching thesecond transistor is
2.5352.5+4.7
of the signal at the output of the first This brings thegain of the first transistor stage down to 180 X .35 =- 63which is the sort of value we usually measure for onestage of a multi -stage amplifier.
With all this going for it, Gm, is coming back, folks.As Sam Goldwyn is supposed to have said, "sim plicateand add lightness- Let's hope we've 'added a bit oflightness today. Ell
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ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
oetbOard4,10C%
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CLICK ELIMINATORPart two of the Click Eliminator article, presented here, is in fact a redesign of theproject leading to better performance and lower cost.
In the January issue of ETI wepresented a design for a clickeliminator unit. However, betweenthat issue and the time for theFebruary ETI - in which we were tocomplete the project we foundseveral disturbing inconsistencieswhich would have rendered thedesign's repeatability doubtful-toput it mildly.
These problems mainly concernedthe area around Q1, IC9 and ICI O.The biasing arrangement for 01, andits function within the circuit meansthat the adjustments are very verycritical indeed. Our prototypeoperated satisfactorily, especially inits breadboarded form, but was toodependent upon too many variablesfor us to be happy with the project.
Taking AimThe aim then, as now, was to presenta design for a unit which wouldremove the clicks and scratches fromdamaged LPs, without impairing themusic material contained therein.
Operation was to be indicated byan LED, and threshold of operationwas to be variable to make theEliminator flexible in use.
However, as we said, developmentwork has continued since initialpublication, and while we felt thatthere was nothing wrong with theaims of the project, our method ofrealising them left something to bedesired.
Change Of TrackAccordingly we are presenting herean alternative design, and
recommend our readers to constructthis in lieu of the design shown inPart One of the article. A comparisonbetween both circuits will show thisversion to be greatly simplified, andusing components which will makeconstruction cheaper.
For example the 570 has beenreplaced with a 4016, which isclosed to the signal for a short periodof time to blank the 'click' signal.
Fig 1. Basic block diagram for Click Eliminator Mk 2.
lx
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979 41
PR
OJE
CT
: Clic
k E
limin
ator
ri1:-
,2',`
,7,',
1,60
Z7:
::,el
'7:,;
1,11
','Z
IT.::
::Trr
el'e
nd,V
:r "
no "
"'"'""
°
HO
W IT
WO
RK
S
The
full
circ
uit o
f the
rig
ht p
re -
amp
and
dela
y lin
e bl
ock
is s
how
n in
Fig
ure
2. th
ele
ft ch
anne
l circ
uit b
lock
is id
entic
al.
The
inpu
t sig
nal f
rom
the
pick
-up
is fe
dto
ICI a
. whi
ch is
wire
d as
a s
.10
inve
rtin
gam
plifi
er w
ith a
n in
put i
mpe
danc
e of
47k
.T
he o
utpu
t of t
his
stag
e is
fed
to th
e cl
ick
deltc
lote
tcut
laet
llcttl
hseh
tcht
sw
ired
as a
sec
ond
orde
r lo
w p
ass
But
ter-
wor
th fi
lter
with
a tu
rnov
er p
oint
of a
bout
10 k
Hz.
Thi
s st
age
also
has
a s
mal
lam
ount
of g
ain
in it
s pa
ss h
and.
The
out
put o
f the
But
terw
orth
fitte
r is
fed
into
inpu
t pin
-5
of 1
C2,
whi
ch is
a T
DA
1022
512
-st
age
char
ge -
coup
led
dela
y lin
e.T
he R
O-R
VI-
R11
-R12
and
RIO
net
wor
k at
the
inpu
t of t
he IC
eas
ed to
set
pin
-I3
at
abou
tI
volt
abov
e go
mnd
. to
ensu
rem
akm
nurn
dyn
amo:
. ran
ge o
n th
e de
lay
line
and
m N
esIn
to c
lass
A a
tm
inim
um li
stor
tinn
rhe
dela
y lin
e is
cloc
ked
to)
sym
met
rical
ant
i pha
sesi
gnal
s to
pin
, I a
nd 4
at s
few
hun
dred
kHz,
to p
rovi
de a
tota
l del
ay o
f abo
ut I
rnS
. yhcc
ttlyu
l of t
he d
elay
line
as
take
n. v
ia(4
. to
anot
her
seco
nd o
rder
But
terw
orth
filte
r 11
C3)
, whi
ch r
emov
es th
e un
wan
ted
high
freq
uenc
y cl
ock
sign
als
that
are
impo
sed
on th
e au
dio
sign
al b
y th
e de
lay
line,
and
the
clea
ned
-up
sign
als
are
then
pass
ed o
n to
the
clic
k bl
anki
ng c
ircui
t ,a
voln
me
cont
rol R
V2.
As
the
bloc
k di
agra
ms
of F
ig.
1
will
sho
w, t
he b
asic
rem
ains
unch
ange
d. T
he in
com
ing
audi
o is
del
ayed
by
a T
DA
102
2.lo
ng e
noug
h fo
r th
e ci
rcui
t to
dete
ctth
e cl
ick
and
gene
rate
a p
ulse
whi
chsh
uts
off t
he tr
ansm
issi
on g
ate
(401
6) a
s th
e 'c
lick'
arr
ives
.T
he w
avef
orm
s sh
own
in F
ig. 6
give
an
indi
catio
n of
the
timin
g of
the
circ
uit,
and
the
man
ner
in w
hich
the
blan
k pe
riod
is m
ade
to 's
trad
dle'
the
clic
k si
gnal
.
Circ
uits
and
Com
pone
nts
Fig
ures
2-6
sho
w th
e sc
hem
atic
for
the
Clic
k E
limin
ator
. Fig
ure
2 is
the
audi
o in
put a
nd d
elay
line
circ
uit.
Fig
ure
5 sh
ows
the
clic
k de
tect
ion
and
blan
king
pul
se g
ener
atio
nco
mpo
nent
s. In
puts
A a
nd B
com
efr
om p
oint
s A
and
B m
arke
d on
the
left
and
right
aud
io in
puts
resp
ectiv
ely.
Circ
uits
5 a
nd 7
are
the
outp
utbl
anki
ng (
and
bypa
ss)
and
syst
emcl
ock
resp
ectiv
ely.
The
latte
r is
refe
rred
in th
e au
dio
circ
uit s
impl
y as
()an
d Q
.
Con
stru
ctio
nT
he u
nit i
s as
sem
bled
ont
o a
sing
leP
CB
. and
so
cons
truc
tion
is r
eally
guile
str
aigh
tforw
ard.
Ass
embl
e th
ebo
ard
care
fully
, rem
embe
ring
to fi
tre
sist
ors
and
capa
cito
rs fi
rst,
and
ICs
last
. Soc
kets
are
bes
t use
d fo
r th
ese
devi
ces,
esp
ecia
lly th
e hi
gh c
ost
item
s. T
his
will
faci
litat
e ch
ecki
ngan
d se
rvic
ing
shou
ld th
is b
e ne
eded
.T
he e
asie
st p
lace
to m
ake
am
ista
ke is
in fi
tting
the
pola
rised
com
pone
nts
- el
ectr
olyt
ics,
dio
des.
ICs
etc
so c
heck
thes
e ca
refu
lly. I
t is
best
to b
uild
up
the
PS
U fi
rst a
ndch
eck
this
bef
ore
conn
ectin
g to
the
rest
of t
he c
ircui
t.
tOtW
o
Fig
3. C
ircui
t of t
he c
lick
dete
ctor
sec
tion
of th
e M
k 2
Clic
k E
limin
ator
. The
LE
D fl
ashe
sto
indi
cate
ope
ratio
n.
of
*r^
Ast
044.
0000
604.
0
Fig
4 (
a). A
bove
: the
wav
efor
m o
f the
Clic
kE
lillli
1101
0, b
lank
ing
puls
e st
radd
ling
the
clic
kw
avef
orm
, whi
ch in
clud
es s
ome
ringi
ng. F
ig4(
h). B
elow
: the
com
bine
d w
avef
orm
msh
owin
g th
e bl
ank
perio
d in
sert
ed in
to th
eus
ic. --0.
4040
0,11
0
HO
W IT
WO
RK
S
The
full
circ
uit d
iagr
am o
f the
clic
k de
-te
ctO
r bl
ock.
whi
ch in
corp
orat
es a
"cl
ick
iden
tifie
r,"
a th
resh
old
dete
ctor
. and
abl
anki
ng p
ulse
gen
erat
or, i
s sh
own
inF
igur
e 3.
A "
clic
k" o
r sc
ratc
h ha
s a
num
ber
ofun
ique
cha
ract
eris
tics.
It h
as fa
st a
ttack
and
deca
y tim
es, a
nd it
s ou
tis
con
se-
quen
tly r
ich
in h
igh
-fre
quen
cy c
om-
pone
nts.
Als
o, it
app
ears
to a
ste
reo
pick
up h
eed
as a
set
of r
ecor
ded
anti
-ph
ase
sign
als,
sin
ce it
cau
ses
pure
ly v
esU
ral d
ispl
acem
ent o
f the
sty
lus,
whe
reas
norm
al r
ecor
ded
sign
als
tend
to b
e in
phas
e an
d ca
use
pred
omin
antly
hot
izon
-ta
l mov
emen
t of t
he s
tylu
s. T
he E
TI C
lick
Elim
inat
or u
ses
thes
e un
ique
pha
se c
ha-
ract
eris
tics
to p
rovi
de it
s pr
imar
y m
eans
of c
lick
iden
tific
atio
n.In
the
circ
uit.
the
ampl
ified
pic
k-up
sign
als
are
take
n fr
om th
e ou
tput
s of
the
andc
hann
el p
ream
plifi
ers
(IC
la, F
ig 2
,ar
e pa
ssed
to o
ne o
r ot
her
of th
e tw
oin
put t
erm
inal
s of
IC4
in F
ig 3
IC4
isw
ired
as a
diff
eren
tial a
mpl
ifier
or
"sub
-tr
acto
r,. a
nd h
as a
gai
n of
abo
ut fi
ve o
n
each
inpu
t. T
he a
ctio
n of
this
IC is
suc
hth
at it
am
plifi
es th
e an
ti -p
hase
"cl
ick"
sign
als,
but
tend
s to
can
cel t
he p
re.
dom
inan
tly in
.pha
se r
ecor
ded
sign
als.
so
that
the
outp
ut o
f the
IC c
onsi
sts
of a
nau
dio
sign
al w
ith g
reat
ly e
mph
asis
ed"c
licks
." T
his
sign
al is
pas
sed
to th
resh
old
dete
ctor
IC5,
whi
ch is
wire
d as
an
open
-lo
op v
olta
ge c
ompa
rato
r, w
ith it
s ou
tput
norm
ally
at p
ositi
ve s
atur
atio
n.T
he "
thre
shol
d" le
vel o
f (C
5 ca
n be
adju
sted
via
pan
el -
mou
nted
con
trol
RV
3,so
that
the
outp
td o
f.the
IC ik
just
hel
dhi
gh th
roug
hout
the
pass
dge
of a
"cl
ean"
reco
rd T
hen,
eac
h tim
e th
at a
..cl
ick"
arriv
es, t
he o
utpu
t of I
CS
sw
itche
s hi
nega
tive
satu
ratio
n, to
pro
duce
a la
rge
nega
tive
-goi
ng p
ulse
. Thi
s pu
lse
is u
sed
totr
igge
r m
onos
tabl
e m
ulti
-vib
rato
r IC
S.
whi
ch h
as n
per
iod
of a
bout
5 m
S, a
ndw
hich
driv
es "
clic
k in
dica
tor"
LE
D I
onan
d dr
ives
out
put t
rans
isto
r Q
I so
satu
-ra
tion
for
the
dura
tion
of th
e 5
mS
pul
se.
The
out
put o
f Ql a
ppea
rs a
s a
blan
king
puls
e, a
nd is
fed
to th
e cl
ick
blan
king
circ
uit o
f Fig
4.
Lg?ral.o
71!
OV
Fig 5. Clink btaskieg niseait. ""'""'
HOW IT WORKSThe circuit of the click blanking block isshown in Figure 5. Circuit operation isfairly strMghtforwand. The output of eachchannel is taken from im volume control(Fig 2) and is fed through a times -teninverting amplifier (ICI or IC9). and isthen passed to one half of ICS, a4015 goadbilateral switch. In each channel. two ofthe internal ',witches.' of the 4016 arewired in series. and are normally held onby the high control signal from the col-lector of QI (Fig Q. but turn off for 5 mSwhen a blanking pulse arrives from theclick detector circuit, The output of eachchannel is then passed on to the outsideworld via a divide-hyten (sm..) MM.nuator network.'
Thus, dining "cleari" parts or the recordthe output signal from the delay line ispassed through the click blanking circuitof Fig 5 via the two series -connected on
The power supply is a straightforwarddesign based on a pair of threeterrninalIC regulators. which provide plus orminus twelve volt outputs. LED 2 is apanelmounted component, which indimess the power on state.
Next assemble and check theaudio circuitry. Make sure a signal ispresent at the level control RV2a andRV2b, Normally IC8 gates will be'open' and so an audio output shouldbe present at the phone sockets if allis well.
If no output is present, check theaudio through to RV2. and if a signalis present here, the fault probably lieswith IC6 and QI . Disconnecting thebase of 0.1 will restore output if thisis the case.
Over the ThresholdIn use the unit is connected betweenthe output of a record player pick-up
44
switches of ICS with negligible loss orgain, but in the presence of a ',lick" thetwo series -connected switches of IC8open I mS before the arrival of the clickand remain open for about 5 ins, thusreplacing the click with an imperceptible
Note in the circuit that the inputs of IC8are biased at half -supply volts to enable
the IC to pass signals with a minimum ofdistortion when operated trots a single -ended power supply. The 4018 IC suffersfrom a certain amount of control -signalbreakthrough; by using a times -tenamplifier before the input and a divide,by- ten attenuator after the output of theIC. this breakthrough is reduced to in.significant levels relative to those of thebasic audio signal.
V011,
Fig 6. Power supply fort. unit. aiDand the input of a stereo amplifier.Volume control RV2 should beadjusted so that no perceptibledifference occurs in audio soundlevels when the bypass switch isswitched in and out Pre-sets RV1and RVI 01 should be adjusted forminimum distortion on the Right andLeft channels respectively. Thresholdcontrol RV3 should be adjusted inuse so that LED 1 just operates in thepresence of a 'click'.
It should be noted that the relativeamplitude of a 'click- is proportionalto the velocity of the record track pastthe pick-up head. and decreases asthe head moves towards the centre ofthe disc: the threshold control may
ONO
consequently need o casionalreadjustment as the ecordprogresses through i s play.
There is no equali ation circuitrywithin our design, and so it cannotbe used in place of the preamp inyour system, it must be used in frontof n instead.
When playing damaged LP'ssimply advance the Thresholdcontrol. RV3 from its minimumsetting until the click is removed.This is the correct setting.
LED 1 will indicate the unitoperation, and it it flashes on musicalpeaks, chances are you have thethreshold control set too high and areremoving some of the signal as well.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
PROJECT: Click Eliminator
ff=:1 1=111=1 1=1
6e as
C1,',
n :
BUYLINES
Being composed mainly of'standard' components, theEliminator should pose most com-ponent shops no problems. The LF356 is available from Watford incase of difficulty.
CD=1=
<7.7>
CD
<7",:, 4=3,ir-o-er
1=1,ni FROM
CDT,
CZ,1:711 4=/f==/ 1=1.
= C=11=11=3
Fig 7. Component overlay for th Click Eliminator unit. Note thatall the components bar the potentiorn mount on this PCP.The operation LEO is also best front panel mounted.
PARTS LIST
RESISTORS (at VeMr 5%)POTENTIOMETERS SEMICONDUCTORS
29.45 47kR2 470k
RV1RV2
dk7 preset100k log twin gang
ICI TL083IC2 TDA1022
114, 17, 23, 25,33.37, 39.44 10)
RV3 5k Lin 1C3. 5 LF 3581C4, 7 9 741
135, 6. 30, 3135, 36, 41 42 15k
106 555co1 4016
07, 10. 14.15. 16. 20,
ICI 0 4011IC11 4013
22, 23 34,43 100k CAPACITORS
IC12 780 2IC13 79112
RB 56k0.9 257
01. 2, 1503, 4. 9,
330P Pc941414"4 Ell BC 10901,04 19 4001 ,
Rif 6k8R12,27. 28 , 10, 16 -
C5T IO-On polyester.56p ceramic
"Coal. 2 TIL 220
R18. 24 4k7 co 1.00p ceramic
021, 26, 32 226038. 40 1k8 k2
C7CO
lOn polyester202 polyester
R46 1C1I-14C17. 18
4u7 25V electrolytic MISCELLANEOUS1000u 25V electrolyte240/12.12 trenslorrner 1100mA). rum
55RH channel i6etical
1s-tors
101-118 Mr C19. 20 410n polyester (34) end holder, case to sot. SPOT mains
ear -18 C21 22 47u 25V elecoolytm switch control knobs. PCB
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979 45
PROJECT: Click EliminatorTHE SINCLAIR PONT Digital riluitiineter
Figs Clock generator ChM,.
HOW IT WORKSPins& and of the TDA 1022 delay line IC each channel via a buffer stage (IC10d ,Jrmust be presented with symmetrical ICI0c) and a D -type RIP -flop (ICI la oranti -phase clock signals for correct ICI1b), which provides the required anti -operation. The basic clock signal of a (ew phase drive signals (from the Q and Qhundred kHz is generated by a CMOS outputs) for the delay line The cluck
'astable muluvibrator formed by !Ma generator has SF decoupling provided hiseth cob. The clock signal is taken to CIA. which is mounted close to the supply
pins of ICIO and ICII.
%%Ma=
.stivaz,
Close up of theSocket wiring forthe Cock Elimina-tor. Keep... asclose to the boardsas possible, anduse sc eeeee dloads if this is M.possible, earthingonly one end of theSLAP..
46
Fig 9. Sometaldeal waveformswhich illustratethe timing of Mecircuitry withinthe general blockof the ClickEliminatorBlanking pulsewidth is fixed.
SINCLAIR DM235
SINCLAIR DM3500 DM450
KRAMER & CO
H & S ELECTRONICS
TRAINAMThe exciting new
TRITONPersonal Computer
EXPANSION BOARDS
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12 CUM STRUT
P.FI OOP AMMER
pmicRopion-Aupm,parl4110
weihi
MICRODIGITAL LTD.,2.?,,BEWORfigOITJREETTel' 051 218 0707
TIONAL - APRIl 979
ETIPRINTS are a last new aid for pro- ETIPRINTS are made from our originaldiming high quality printed circuit artwork ensuring a neat and accurateboards. Each ETIPRINTS sheet con- board. We thought ETIPRINTS weretains a set of elCh resistant Mb down such a good Idea that we havetransfers of the printed circuit board patented the system (patent numbersdesigns for several of our projects. 1445171 and 1445172).
LISTEarlier earners re available.
I1,
WORKSLey ilown the 'TIMM, andrub over with son pencil
:IT =7: 7;:board. Peelof,. flocking sheet
you'. been bit careless
b..s!
SUS LINOSORDER TOD.
75p INC P IL P49
data sheet
Operational Amplifiers pp Amps]
Audio AmpIdlers
Multipliers
Oscillators
CHART I OP AMP - ABRIDGED PERFORMANCE
U., eat
Comments
TM T 3. `t. 0 25 50 a 03 50 5
997 2 70 NPN 1 0 25 100 +18 90 5 60.03401mercenms0b00
991 2 70 NPN 10 0 5 100 +18 90 5
741 2 80 NPN 1 0 6 106 +18 90
748 t 120 NPN 10 0 5 103 222 90 5 0 00000,000.010.1001
300 2 1 5 NPN 3
° 9 'iitri:=Z;177:Ze70.00319 3 150 NPN 15 50 106 +20 100 5
707 2 80 NPN 1 0.5 106 +113 90 0 6000006,0.1.0000001498 80 NPN / 0.8 103 +18 90 04136 0 5 00 PNP 3 1.0 110 +18 100 039809001
Curreniinputs
30 Currentsinks
2.5 0.5 70 +18 - 0 belen.in,rnaiw
924 2 06 PNP 1 0.5 100 +30 7°
9409 2 150 PNP 1 1 2 100 +38 9" )
FDA1 30 Nell 1 0 5 103 SIB 90 0 I
52 ELECTRONICS TODAY IN7.19.109111. - APRIL 1979
NEWS
"777 rz.zrx...z=
'117 zr..4=::::-
'1'1311
11=
1,7
zgn
i11
' -°"
EGG Or PAIS - MGM PRINIMMANC6
FfL,Comments
RG7S9 2 4D PNP 3 1 110 +18 100 °
G739 t 300 NPN 10 1 86 +18 90 0
. +20
applicable WOG.WIG 8 0.005 IN (WET 15 10 110 +16 90 ,r,157,76;62,FFiz....t.
C0140 8 0.010 N1OSFET 4.5 9 100 +36 90 :74=7'4=4 66C96169 6 0.005 MOSFET a lo als so e t=1;,..7,6;=,6.6';:,,REMRC4521
2 400 NPN 10 35 96 822 100 5
CP3080 0 4 NPN 2 50 8- 18 110 S
C0.6094 0 48.00 N N
30 50 1"RAN 15 0.4 JFET 3 13 83 4113 70 S ,., me
71.0111 15 0 4 JFET 3 13 83 -P 18 '° Z4= 741" F.77992 15 0 4 JFET 3 13 83 8-18 70 8 1123
0 4 3 13 83 70 P
11014 0 4 J'F'E'TT 3 13 83 -.118 70 320
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
ia
P.a.. t. Call 'timer circuit.
This new feature is open to all our readers. Itexists as a showcase for projects YOU have des-igned and built. We pay full ETI page rates for
any designs we publish. We must stress thatthese designs must have been built by you. Tofurther this end, we are giving preference tothose which arrive at our offices with photo-graphs, or which can be photographed by us.
Initially a simple draft outlining theidea behind the project and what the unit
can do is all that is required.> Photographs should be included at
this stage.
J
Write to'Readers De-signs,' ETIOffices, 25-27Oxford Street,London, W1 R1 RF.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979 55
(A DIVISION OF GOTHIC ELECTRONIC COMPONENTS LTD)
PO Box 2908 Hampton Street
TELEPHONE:MAIL
ORDERELECTRON/CS Birmingham B19 3JR 021.233.2400 ONLY
ALL PRICES IN PENCE EACH UNLESS OTHERWISE STATED
LLECTF N CS TODAY INTER,TIONAL - APRIL 1979
ACCESS FREEPOST ON ORDERS GMT ELECTRONICS BARCLAYCARD VAT INCLUSIVE PRICES Freepost CASH ADD 30p P&P Birmingham B19 1BR CHEOUE 24 HR TELEPHONE ANSWERING SERVICE z_
CLOCRADIO
111.="MD
£20.50
LADIES DIGITALLCD WATCH ALARM
£9.95vox 1
fia,...,,
£8.95--v. of VAT on0 Ponagel
immT4iLVi- AlrDIGITAL ALARMALARM MK2 CNRONO LCD
LCDCOMORO
£12.95 £10.50 E27.95
010117.1. ALARM CLOCK MI12 1.
ftvc,-nr-
ELEUROMCSTODAYINTERNATIONAL-Ain
PROJECT
AMBUSH! is bound to rate as the most fascinating, exciting, and addictive space gameof the year. It gives visual and sound effects of a space battle. and is loaded withrealism. Impress your friends land enemies) by building this unique and fascinatinggame.
AMBUSH. soacegarne
rvKZZnZI':=rni'o'rZt$:=45eh:hv a fleet of Surto. craf t The craft
=c:O=tk:e7:C1':[17:aVan:
tOtvOPMeen nOMOilt and hve seconds
tenet ...one el low [ref btolion1
fare
2rta'-o'kt:;:-"''."111;11VE1=
:==ca:Wer:17:t2Te"sn't:rM. of game chosen A Of It gan.
gz.741417,1==.1
sound And Light
ELEC-rtOVCS TODAY orrf Pa lots. - APRIL 1479
101 volumerho ef loos are also quite
impress.. The attacks are 00,4n by
form of a croM wth at.e Of var.,Wr,s The of.. arm representsthe 10tward Mack quad.. at.
...range S Thelower arm reOresenis Ole aft allat.
,F0 s the portant! starboard...5eact,CO.O.s. so yeffew LED s .the centre onne voss ,arl LED
Science ProjectAmbush! is a CMOS based design ofconsiderable technical interest, andshould make an excellent educationalproject for schools and colleges. Ituses seventeen IC's plus a couple oftransistors. The IC types range fromsimple NAND and NOR gates tocomplete decade counter -decoderchips, and include flip-flops. datalatches. 12 -stage ripple counters.and multiplexers.
Playing The GameGame Stan. The game starts assoon as power is applied to itscircuits. A game can be restarted bypressing the RESET switch.
Attacks:(1), The game can be set for playagainst either ten (a DEM or ahundred (a CENT) attacks.
(2). Attacks come at randominterval, variable between noughtand approximately five seconds.
(3). The quadrant of each attack israndomly selected. except for thefirst attack of the game, which always
ETI ir.,,a4vaii
111
comes from the aft quadrant(41 The speed of attack can be
pre-set by the player to suit skilllevels. A 'respectable' attack speed isequal to about 50 mS per LEDdivision on the quadrant attackindicator.
(5) At 'respectable' attack speeds.the player has approximately 250mS of attack warning on the forwardquadrant, 300 mS on the port and
*0 0
ID a IDnwo ooo ir:**
.......
starboard quadrants, and 350 mS onthe aft quadrant
(6) Attacks on the aft quadrantare accompanied by a full volumestaccato sound. Port and starboardattacks are at reduced volume. andthose from the forward quadrant aresilent
(7) The accumulated number ofattacks is registered on a 2 -digitdisplay throughout the game
HOW IT WORKSSIMPLIFIED BLOCK DIAGRAM OFTHE AMBUSH GAME
The heart of the unit is the 'DisplayMatrix Driver and Logic' block. which inreality takes the form of a 4017 decadecounter with ten decoded outputs Out.puts Ito 7 of the counter ale fed to theLED display matrix. and outputs 6 to it areselectively fed via a multiplexer to theGAME LOST indicator block and to theCI.00K DISABLE pin of the 4017. Theinput of the 4017 Is derived from s clackgenerator via a gate. which to turn iscontrolled by a simple START -STOP(Reset .Set)blotable.
The operating sequence of the abovesix blocks is fairly simple. Initially. theblstable Is in the STOP mode the gate Isclosed. the 4017 Ole the RESET state. andall LED's in the display mama are off. Atseine randomly determined timeSTART pulse 0 fed to the listable thegate opens. clock pulses start so reach the4017. and LED's are oequentially switchedon in one of the arms of the displaymatrix. If the gate remains open. one ofthe selectively chosen 6.7.S outputs of theIC eventually goes high and operates theGAME LOST.indicator and disables theclock input line of the 4017
Alternatively. the bistable can be set tothe STOP mode before the game term.,ales by operating the appropnate FIREswitch. In this case the bauble closes theclock pte. and the 4017 resets to the zerostate A- new sequence of operations startowhen another random START pulse fed
to the Input of the tastable. Nate thatoutput I of the 4017 is fed to the ATTACKCOUNTER. so that the counter advancesby one count each time the clock genera
fit
Figs. to and b. Sim-phfied mock diagramof the Ambush game.
H
Fig. ,
-a
for gate opens, fhe game ends shortlyafter the attack counter reaches its full let10 or 1001 state, at which point the GAMEWON indicator circuits come into opera.non.
The START signal to the listable isderived from the random delay generator.which zo integral with the FIRE switchcircuit,. In each attack, the appropriateoe of the four FIRE switches is selecfinely coupled the STOP side of thc
ELECTRON:CS TODAY INTEPherlOhe:_ - APRIL 1979
PROJECT:Ambush
(debt) This boardcarries LED displaymatrix drivers,multiplexers andlogic, plus audioand powerconnections.
Defence
(a). The player has four FIRE buttonsfor defence. The buttons are markedF (forward). P (port), S (starboard).and A (aft). To stop an attack. theplayer must press the FIRE buttonappropriate to the prevailing attackquadrant. before the attacking vesselreaches its target (the red LED at thecentre of the display) A correct firingis accompanied by a rasping sound
(left) ICs 2 and5-11 mounted
an Ambushacs.
No sound is produced if the wrongbutton is pressed.
(b). The ship has sufficientammunition to fight off attacks only ifeach FIRE duration is limited to about100 rnS or less. Thus, there issufficient ammunition for about onesecond of continuous fire in the DEKgame, and ten seconds of fire in theCENT game. The ammunition state isshown on a register throughout thegame
(c). When the correct FIRE buttonis pressed, the rate of ammunitionusage is directly proportional to thetotal number of FIRE buttons that arepressed at that time. Thus, if all thefire buttons are pressed at once, theammunition supply will exhaust in0.25 seconds in the DEK game or2.5 seconds in the CENT game. Theaudio frequency of the FIRE sound isproportional to the rate ofammunition usage. When theammunition store is exhausted, theplayer has no defence, and loses thegame after the next attack.
Game Lost. The player loses thegame by having his starship hit by anattacking suicide craft. When thegame is lost the red LED at the centreof the attack quadrant indicator turnsoff, and simultaneously a louddroning noise is generated and a redGAME LOST LED flashes on thecontrol panel.
Game Won. The player wins thegame by defeating all attacks. AtGAME WON a green LED illuminateson the control panel. and a coarsebeating or throbbing sound Isgenerated
!listable On a multiplexer and a qmulated
activates the correct switch: thefrequency of thetfire' cooed is determinedby the FIRE RATE SELECTOR circuit.and Is proportional to the 50151 number ofFIRE snitches preeed at any given mnMen(
The output of the fire sound generatorurea to Mite the ammunition register.
which counts and gives a visual readoutof the total number of cycles generated.The sound it also used to generatelatched random 'select' code for the fourmulltplexers that are used in the game.These multiplexers are used for FIRE
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
switch selection, for LED Display Matrixline and line length selection, and todetermine the audio levels bf theATTACK tarot
The ATTACK. FIRE, WIN and LOSEsound signals are all ted to a simpletwo -transistor audio amplifier whichdrives a 40 ohm output speaker,
63
HOW IT WORKSRANDOM DELAY and 'FIRE SOUNDGENERATOR, plus 'FIRE' RATESELECTOR and FIRE SWITCH MULTI.PLIDCER
THIS IS probably the most complexMock' in the entire game, because mostof Its individual sections are interdepen-dent. Fig 2 shows the circuit diagram ofNis major 'block'.
THE TIRE' SOUND GENERATORLet's deal first with the 'FIRE SOUND
GENERATOR. IC2 d one half of a 4052dual 4 -channel multiplexer. This connectsouselected one of its four inputs to its
tput. depending on the 'a - b' binarycode signal that is fed to its 'select' (pins 9and 10) terminals. Thus, when the appro./Mate one of the four FIRE switches ispressed. a logic -1 signal appears at outputpin -3 of the multiplexer. This signal isiebounced' by R6 -C6 and R7. and ispassed to the signal input of the INHIBITGATE formed by IC3,3 and IC3i4.
It passes signals only when itsGALE input is at logic -0: pin -1 is the 'G'terminal of this particular gate, and is tied
grefafid vie RS but can be driven highby the outputs of the LOSE and OUT OFAMMOdetectors. The gate thus passes onthe FIRE switch signals only when die
game is not lost and the ammunition store
Theis not exhausted.
output of the inhibit gate is used toactivate a gated TIRE' sound oscillatordesigned around IC5,3 and IC5:4. Themain timing components of thisosultator are C2 and RI2 to RI5. Thesetiming resistors are connected via ICI,which is a 4016 quad bilateral switch.which has each of its four internal
witches' activated by one of the fourFIRE switches: these internal switchesaxe Connally open. and close when theirappropriate FIRE switch is closed.
Thus. the complete action of the 'FIRE'and generator is such that a and is
produced only when the 'correct: FIREswitch is pressed, and only when thegame is not lost or the ammunitionexhausted. The frequency of the sound isproportional to the total number of FIREs,vitches pressed and varies from about800 Hz for one switch, to about 320 He forformeitcn-4 h
output of the 'FIRE' oscillatoris low in the normal quiescent state, andits signals are passed to the input of anaudio amplifier for sound effects, and alsoto the inputs of the ammunition registerand the Random Delay generator. Aninverted output (normally high) is alsotaken from the pin 3 output of theoscillator and is fed to the WIN LOGICcircuitry. Note that the gate Input signalof the oscillator is also fed to the STOP
side of the bistable and to the RESET pinof the display matrix driver. so that IC12is reset each time the correct FIRE switchis pressed.
THE RANDOM DELAY GENERATORThe heart of the random delay genera.
tor is IC4, a 4017 decade counter with tendecoded outputs (numbered 0 to 9): the 'Poutput of the counter is coupled to theSTART side of the bistable vianormallyON inhibit gate The clock inputto the counter is derived from a slow(about 2 14z) oscillator (ICS- I and IC5/2)and from the 'FIRE' oscillator output viaan OR gate formed by DI -132 and R3.
Whenever the correct FIRE button ispressed during an attack a logiml signal isfed to the '0' (pin 131 terminal of theinhibit gate, which bums off and blocksthe signals from the 4017 counter.Simultaneously. fast clock signals are fedinto the counter from the 'FIRE' soundgenerator. Consequently. when the FIREsynch is released and the inhibit gatereturns to the ON state the counter is anunknown or random number of stepsfrom the 9' count (which is the one thatprovides the START signal to the hist-able). Clock signals are th fed to thecounter from the slow oscillator onlyuntil. after a delay that is infinitely vari-able from zero to about five seconds, thecounter reaches the '9' stale and feeds a.START command to the bistable.
Fig. Z. Circuit diagram of random de-lay, fire sound generator, fire rateselector and fire switch multiplexer.
HOW IT WORKSTHE HISTABLE, CLOCK GENERATOR.'ATTACK' SOUND MULTIPLEXER.AND 'GAME Lost INDICATORSTHE BISTABLE is a simple R -S type,made from a pair of NOR gatm(1C9/1 and1C9,2). Its 'START' input is derived fromthe random delay generator via C4, and'STOP' inputs are obtained from the'FIRE logic or theGAME LOST detectorcircuitry via the Dl.D7-R30 diode ORgate. The rift output of the bistable isnmally. high, but goes low in the"START mode. and is fed to one input ofthe IC10,3 NOR gate, which provides theclock Input signal to IC12 (the display.matris counter -driver). Theother input ofthe NOR gate Is obtained from the
variable.speed CLOCK GENERATOR(IC10/I and ICIO.,2) or from the WINDETECTOR circuitry via the D4.D5-R28diode OR gate.
Thus, input pin -6 of the NOR gate isnormally high, and its output is lockedlow, so it is unable to pass clock signals.When a 'START' signal is fed to theMstahle from the random delay genera.tor. input pin.6 of the gate is driven low.and it does pass clock signals. The gate isturned off again when a 'STOP. signal isfed to the histable from the 'FIRE' logiccircuitry. Note that the gate gets lockedNo the off state if a logic." signal is fed toits pin.5 input from the 'WIN' detector
134). or if a logic -I 'GAME LOST'
signal is fed to the 'STOP side of thebistable via D6.
The IC10/I and ICI 0/2 clock generatordetermines the speed of any attack, andIts frequency is variable via RVI. Theclock signal appearing at the pin -II out-put of the IC10,3 NOR gate provides thebasic 'ATTACK' sound of the game. Theamplitude of this sound is determined bymultiplexer IC212 and resistors R31 andR32. Attacks from the aft quadrant are atfull volume, those from port or starboardare at reduced volume, and those from theforward quadrant are silent.
The 'GAME LOST indicators use fourNANO and one NOR gates: their basicinput signals are obtained from pin -13 ofIC12. which is normally low but goes highunder the game lost condition. 103,3 uwired as a simple inverter, and drives the
LI, NIC.- 100,- URN,: 1-L- AFFIL 1
PROJECT:Ambush
Fig. 3 Circuit diagram of ammo register, tendon, muniplex codegenerator and latch with the reset line control.
THE AMMO REGISTER. RANDOMMULTIPLEX CODE GENERATOR ANDLATCH. AND RESET LINE CONTROLTHIS BLOCK is relatively simple in itstheory of operation. IC7 is a 404012 -stageripple counter, and takes its clock inputfrom the output of the 'FIRE' soundgenerator. ICS Is a 1013 dual D flip-flop,which iserired as a dual data latch with Itsclock signal taken from the output of thebistable and its data taken from the 51 (2) and Q2 (04) outputs of IC7. Thus.whenever a FIRE button is pressed andthen released 1C7 sets randomly deter.mined states on the data inputs of 1C8, thenext time that the output of the bistablegoes high (as an attack begins, on receiptof the bistable START command) thesestates are latched Into the 4013 and are
HOW IT WORKSpressed on to the games multiplexers as a2 -bit ornery code.
IC8 h yet another 1017 decade counterwith ten decoded outputs. It has its out-puts fed to a vertical line of ten LED's,which act as the ammunition register.The '0' output of the 4017 sues to the top(FULL level) of then.. and the '9' outputgoes to the bottom (EMPTY level) of thehne. The '9' output also goes to the inhibitgate controlling the 'EIRE' oscillator.preventing the oscillator from workingunder the 'ammo exhausted' condition. Atthe start of each game the counter is resetto zero. so that the line of LED's indicatethe FULL state.
The clock input of the counter Is takenfrom one of the outputs of the IC7 ripplecounter via SW2a. When SW2 is set for a
red LED at the centre of the games maindisplay matrix. This LED is normally on.beet` oes off when the game lost.
(CI 1, I and ICI 1/2 are wired as amedium -speed gated astable. which pro.vides the 'GAME LOST' sound output viaDO and 934. and 1C11,3 and 1C11,4 are
wired as low -speed gated astable. whichdrives a red 'GAME LOST' LED. Bothpstables are normally off. with their out-
uts low. Under the 'GAME LOST con-dition both astables operate, the'LOSE' sound is generated and the 'LOSE'LED flashes on and off.
Fdte", (;:ZAIVITTArITZ:.tor.Fig. 5. (right) Bistable, clock gen.,'ATTACK' sound multiplexer and'GAME LOST' indicators.
DEK (ten attack) Same the Q7 (. 1191output is fed to the clock input of ICEgiving a clock signal of about 6.2 Hz whena single FIRE button is operated, and thuscausing the register to empty in about 1.5seconds When 5W2 is set for a CENT(hundred attack) game the 510 (0 10211output Is fed to ICS. giving a clockfrequency of about 0.8 Hz from a AngleFIRE button, and causing the register toempty In about 11.2 seconds. Thus. to win
DER ame the avera FIRE durationmust beg limited belowge 150 mS in eachattack, and in the CENT game it must belimited below 112 mS.
The games main reset line is activatedautomatically at switch -on via C8 Theline can be operated manually at any timevia RESET button PBS.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979 65
1111.11111111
Fig 6c Audio amplifier.
LED DISPLAY MARTIX DRIVERS.MULTIPLEXERS. AND LOGIC, PLUSAUDIO AMPLIFIER AND POWER SUP-PLY CONNECTIONS
THE MAIN PART of the LED displaymatrix is made up of four lines of LED's.arranged in the forrn of a cross. The upper(Forward) line is five LED's long. thelower (Aft) line is seven LED's long, andthe other two lines are each six LED'slong. The individual LED's in each hoe areselected by IC12. a 4017 decade counterwith ten decoded outputs. and the linesare selected by multiplexer IC13/1. Notethat diodes 015 to D25 are used toeliminate sneak paths in the matrix, andensure that only a single selected LED
HOW IT WORKSturns on at any one time. Eigure6b showsthe positions of the LED's in the actualdisplay. Note that LED t t, at the centre ofthe display, is normally on and representsthe players own vessel.
Prior to the start of each attack IC13 isin the RESET state, so all LED's in thematrix (except LED II) are off. As soonas an attack starts.IC13/1 selects a line oflength 'a' in the display matrix. and
connects the 'tie l' output of ICI3to its own pin.I3 'clock disable' terminal.Thus. when an attack starts the LED's inthe selected line turn on sequentially andrun towards the centre of the cross' if aRESET signal is fed to pin15 of IC12 fromthe 'FIRE' logic circuitry before the 'n I'state is reached the attack is defeated if
6b. Line selection.
Fig. 6d. Panel LEO displa,
the attack is not defeated. pin.I3 of IC12 isdriven high as the counter reaches the'n I' state. and all further clock signalsare inhibited and all GAME LOST indica-tors are activated.
All sound effects signals that ar.egenerated in the game are digital in form,and are fed via gate diodes andamplitude.determining resistors to thesimple QI.Q2 audio amplifier stage. which
The amplifier directly drives a908 speaker. which has transient limitingprovided by Olt
The game is powered by a 12 V batterysupply. and typically consumes 50 mA to150mA of current, depending on the stateof play. Readers can. if they wish. powerthe game via a Ample mains adaptor.
RIR253. 8 9. 10. 11. 31. 40. 48R4R5. 26. 28. 29, 30. 39Re. 16-25, 36. 37. 47R7, 12,13.14.15R27R32R33R34, 41.42. 46R36R38R43R44,45R49.62
PARTS LIST66113 SEMICONDUCTOR390k ICI22k IC2, 1310M 1C3, 9, 10414 IC4. 6. 12IS IC5, 17. 111006 IC]330k ICEI, 16648 IC14, 15680k10k2M2270833R11454708
POTENTIOMETERRV1 IMO
CAPACITORSCl. 5,6 7.8.11, )4.15C2. 3, 4, 10. 12, 13C9
100010n150n
401640524001401740i1434040264013
NOTE All CMOS &summate B Series.
01 BC10902 8FY50014 184001All Other diodes are 184148LED 1-37 are standard 0 2in dmLED 7 segment displays are commoncatnocle 0.3in
MISCELLANEOUSL.51 21n 4OR5 olISPST push buttons1 oft SPST latching ono button1 off DPDT min. toggleEl off oPt12 on 4 section battery holderscase tO SAllt
BUYLINES
The case we used for theAmbush project is availablefrom Boss Industries. Fulldetails next month. Sincepanel layout is not critical,inventive ETI readers may beable to come up with theirown hardware designs. Allthe ICs are common types,available from most com-ponent mail order firms.
If you think you are likelyto spend every waking hourzapping the starfleet, it'sworthwhile investing in amains adaptor, availablefrom your local Tranny shop.
ELECTRONICS TODAY INTERNATIONAL - 1979
PROJECT:Ambush
THE ATTACK COUNTER AND GAMEwon detector and indicators
THE 'r OUTPUT of 1C12 (the displayrnatnx driver) briefly goes high at thestart of each attack. This 'I' signal pro.vides the clock signal to the 1C11 -1C15ATTACK COUNTER. These two IC's are4026 decade counteis with decoded out.puts suitable for directly driving commoncathode 7 -segment LED displays at lowpower levels. The two counters arecascaded. to give 00 to 99 indications'
HOW IT WORKSleading zero suppression is not used in theCOLIMA,
The 'GAME WON' detector is designedaround IC16. a 4013 dual D flip.flop. endICIOol, a NOR gate. IC16/I is connectedas a bistable divider stage. and is clockedvia one or other of the attack counteroutputs. The action is such that its Qoutput is normally high, but switches lowat the stan of the 10th attack in a DEKgamor the 100th attack in a CENT game.The Q output is fed to one of the inputs ofthe IC10/4 NOR gate, which has its other
Fig. 7 (left) Circuit diagram of display drivers. inultiplers and logicwith audio and power connections.
Fig. 8 (below) Attackcounter and 'GAMEWON' detector and int,cators.
input provided from the normally -highoutput of the IC5 'FIRE' sound generator.The output of the NOR gate is fed to theSET (pin8) terminal of 1C16.'2. which Wwired as an R'S flip-flop. Both bistablesare reset at the start of each game.
The action of the complete 'GAMEWON' detector is such that 'FIRE' signalsare fed to one input of the NOR gate eachtime a 'FIRE' signal is generated. but areunable to reach IC16/2 until ICIO/1changes state after the start of the 10th(m a DEK game) or 100th (in a CENTgame) attack. at which point the Q Outputof IC16/2 goes low and drives green 'WIN'LED 37 'ON' via 1C9o1. and the Q outputgoes high and activates the 'WIN' soundgenertor.
The 'WIN' sound generator is designedaround IC17.and consists of two virtuallyidentical inediumfreguency gated ast-able multivibratorg which am operated inparallel and have their outputs fed to theaudio amplifier via the D26.D27.R46diode OR gate. Because of inevitableslight differences in timing componentvalues. these two eatables oscillate atslightly different frequencies. and pro-duce a coarse 'beating' or 'throbbing'sound when they are activated by the'WIN' detector.
I=I
Next month we conclude the project with fullconstructional details and component overlays. Inaddition we'll show you the act of inspired heroismwhich led to the saving of the starship Eatyeighand the designing of this project! For those who toget started the Parts List and circuit diagramsgiven here are complete.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
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ELECTRONICS 100,1 INTERNATIONAL - 107
SPECIALS57:11-2,R;.c-
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CIRCUITS
No2
ORDER FROMSnook. Mo... Ltd 25.27 Word Street London WIR I lir
from ETIELECTRONICS 700,19 191,9,10 - 9,1111 19,,
3080 CIRCUITSThe 3080 is not a run of the mill op amp. These ten circuits from Tim Orr showyou why.
The CA3080 is known as an operational transconduct-ance amplifier. (OTA). This is a type of op amp, the gainof which can be varied by use of a control current, (1A8c).The device has a differential input, a control input known
Voltage Controlled AmplifierThe CA3080 can be used as a gain controlling device. The inputsignal is attenuated by 51. 52 such 'het 20 mVIIIP m... Ioapplied to the input terminals. If this voltage is much largerg, thensignificant distortion will occur at the output. In fact. .isdistortion is put to good use in the trlangle-to-oinewave con-vener. The gain of the circuit is controlled by the magnitude ofthe current lase This current flows into the CA9080 at pin 5.which is held at one diode voltage drop above the -Vcc rail.If you connect pin 5 to 0 V. then this diode will get zapped, (and
Vibwill the ICII The maximum value of Mc permitted is I ma ande device is linear' over 4 decades of this current. That is, the
gain of the CA3080 is 'linearly' proportional to the magnitude ofthe Ion current over a range of 0.1 on to I mA. Thus, bycontrolling losc, we can control the signal level at the output.The output is a current output which has to be 'dumped. intoresistive load (115) to produce a voltage output. The outputimpedance seen at IC1 pin 6 is 10k IRS), but this is 'unloaded' bythe voltage follower {IC2) to produce a low output impedance.The circuit around IC3 is a precision voltage-tomurrent convenerand this tan be used to generate 1.4 When Vin (control) ispositive, it linearly controls the gaM of the circuit. When it isnegative, loeC is zero and so the gain is zero.
This type of circuit is known by several names. It is a voltagecontrolled amplifier. (VCA), or an amplitude modulator, or a two
70
as the -Amplifier bias input- and a current output. Itdiffers in many respects from conventional op amps andit is these differences that can be used to realize manyuseful circuit blocks.
SIGNALINPUT
- Vcc
V
C/OnNTROL /Ns' ov
OUTPUT 14 VP. itt0 00
quadrant multiplier.One problem that occurs with the CA3080 is that of the 'Input
off set voltage'. This is a small voltage offset between its inputterminals. When there is no signal input and the control input isvaried a voltage similar to the control input will appear at theoutput. By adjusting R VI its possible to null out most of thiscontrol breakthrough.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
FEATURE
Triangle To Sinewave ConverterBy overloading Me input of a CA3080 it is possible to produce a'sinusoidal' transfer function. That is. if a triangle waveform ofthe correct magnitude is applied to the CA3080 input, the outputwill he distorted in such a way as to produce einewaveapproximation. In the circuit shown, Obi Is adjusted so that theoutput waveform resembles sinewave. I tested this circuitusing an alitanlatiC distortion analyser and found the sinews.distortion Be be only 1.8%. mostly third harmonic distortion,which. for such a simple arrangemeM, seems very reasonableindeed. This could be used to produce a elnewave output from atriangle/square wave oscillator.
Vin
POWER FROM± 12V
CA3080
R210k
;ABC
PROTECTIONd, RESISTORAl10k
V HYST tVin
V HYST -
V OUT
OUT
Schmitt TriggerMost Schmitt trigger circuits prove to be very complicated whenit comes to calculating Me hveterysie levels. However, by usingthe CA 3080 these calculations are rendered trivial plus there isthe added bonus of fast operation. The hysterysis !eve. arecalculated from the simple equation,
St v (IPBC X 112)
The output squareweve level is in fact equal in magnitude to thehysterysis levels. The circuit operation is as follows.
Imagine the output voltage is high. The output voltage willthen be equal to (R2 len) which we will call + VMS, If VWbecomes more positive than WM, the output will start tomove in a negative direction, which will increase the voltagebetween Me input terminals which will further accelerate thespeed of the output movement. This is known as regenerativefeedback sods responsibb for the schinitt trigger action. Theoutput snaps into a negative ttttt . at a voltage equal to - (R2 xImc) which is designated as -Mir.. Only when Vie becomesmore negative than - VFW. will the output change base to the+VaVST state.
The Schmitt trigger b very useful building block for
detecting two demrete voltage levels end finds many uses incircuit designs.
+ Sour
+ Vin
I. T/STUMM
LIWITZ1141.".172r
ELECTRONICS TODAY INTERNATIONAL - APRIL 197971
Voltage Controlled OscillatorBy using two CA2080, end some op amps it is possible to makean oscillator, the frequency of which is voltage controllable. Thisunit finds any applications in the field of electronic musicproduction and test equipment. The cirollit has been giveo alogarithmic control law, that is, the frequency of operationdoubles for every volt increase in the control voltage. This makesit ideal for musical applications where linear control voltagesneed to be converted into musical intervals (which are logarith-mically spaced) and also for audio testing where frequencies aregenerally "mred as logarithmic functions.easu
IC2 is an integrator. The Iwo cur eeeee that drives this IC is usedto either charge or discharge C1. This produces triangularwaveforms which are buffered by 1C3, which then drives theSchmin trigger IC4. The hysterysis levels for this device erefixed at - 1.5V, being determined by RC R7.
The output of the schmin is fed back in such a way as tocontrol the direction of motion of the integrator's output. If theSchmitt output is high, Men the integrator will ramp upwards andvice verso Imagine that the integrator is ramping upwards.When the integrators output reaches the positive hysterysislevel. the Schmitt will flip into its low . end the integratorwill start to ramp downwards. When it reaches the lowhysterysis level the Schmitt will flip back into its high state. Thusthe integrator ramps up and down in between the two hysterysislevels. The speed at which it does this, and hence the oscillatingfrequency is determined by the value of laic into IC2. The largerthe current, the faster the capacitor is charged and discharged.Two outputs are produced, a triangle wave (buffered) from IC3and a squarewave (unbuffered) from IC4. If the squarewaveoutput is loaded then the oscillator frequency will change.
The log law generator is composed of . 2, 3 and ICI.Transistors Q1 and 02 should be matched so that their baseeminer voltages (VW) are the same for the same emitter current,(SINAI. Matching thaw devices to within 5 mV issatisfactory, although unmatched pairs could be used. Whenmatching transistors take care not to touch thorn with yourfingers. This will beat them up and produce erroneous measure-ments. Transistor 02 is used to produce a reference voltage ofabout -Ova which is connected to ICI pin 3. This op amp and
72
rue.EDS AVIVER
SE
.5
03 -07
al
VOLTS 0
-mpuENCY
101-0 100Hr lkOo 10101.
-2
-4 --5 -
-Vc LOG CONTROL LAW
03 is u ad to keep 01 emitter in tlas same voltage of -MM.The inp t cOntral college is attenuated by RI, R2 such that a +1Vin ert, se at the input produces a change of only +18 mV at thebase of 01. However the emitter of 01 is fixed at -WM, sothe cur ern through Of doubles. (It is a property of transistorsthat dr collector current doubles for every 18 mV increase inVW).
The twiner current of 01 flows through 03 and into IC2 thuscontroll'ng the oscillator frequency. It is possible to get a controlrange of over 1000 to 1 using Mis circuit. With the valuesshown, operation from 10 In to 10 Mir is achieved. ReducingCI to I n will inc eeeee the maximum frequency to 100 kHz.although the waveform quality may be somewhat degraded.
Changing CI to Sul (non -polarized) soil givefrequency of 0.1 11..
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
FEATURE: 3080 Circuits
TONE BURST GENERATOR
Fast ComparatorThe high slew rem of the CA3080 make it an excellene feetvoltage comparator. when pin 2, ICI is rnore positive then VrefMe output of IC1 goes negative and vice versa. Vref can bemoved around so that the point at which the output changes canbe varied. As long as the input sinewave level is quite large Vsay) then the output can be made to move at very fast aaaaaindeed. However, care must be taken to avoid overloading theinputs. If the differential input voltage exceeds 5 V. then theinput stage Meeks down and may cause an undesired output tooccur.
One use of a feet comparator is in a tone burst generator. Thisdevice produces bursts of sinewaves, the bursts tarting andfinishing on axis crossings of the sinusoid. The comparator is
outputdetect these axis crossings and to produce a square wave
output which then drives a binary divider (IC3). The dividerproduces a 'divide by sixteen' output which is high for eightsinewave cycles end then low for Me next eight . This signal isthen used to gets ON and OFF the sinewave. The gate mechan-ism is a pair of transistor. which shoo Me sinewave to groundwhen the divider output is high and let it pass when the divideroutput is Mid. The resulting output is a toneburst. However, if
compa ttttt is not very feet, then there will be a delay ingenerating the gene and so the tone burst will not sten or finishon axis crossings. Using the circuit shown, operation up to 20kHz is obtainable.
Vin
Vref
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
Vie
LESS THAN4V WRT
V ter
UV/mac
73
POPIRRED FROM IRV
Slew LimiterThe current output of a CA3080 can be used to produce acontrolled slew limiter. By connecting the output curreM to acapacitor, the output voltage cannot move faster than a rategiven by
slew rate Icalc Volts per sec.
Note that Isec determines the slew rate and as Owe is avariable then so is the slew rate. The output voltage is bufferedby a voltage follower, IC2. This is a MOSFET op amp which has avery high input impedance, which is necessary to minimise theMarling on Cl.
When an input signal is applied to ICI the output tries to movetowards this voltage but its speed is limited by the slew rate.Thus the output produces a linear ramp which stops when itreaches the input signal level.
FASTESTR2 Cl SLEW RATE
150k 100n 1.5V/mSec150k 10n 15V/mSec
SLEW LINFOLOOOTRLIT 150k 100 0.15V/m5001M5 100 15V/Sec
Sample And Hold
The slew limiter can be modified so that it becomes a sample andhold unit. In this circuit Mac is either hard ON_ (sample) orcompletely OFF (hold). In the sample Med.. the output yob..quickly adjusts itself so Mat it equals the input voltage. This
74
flIguTT.r.zr-to
enables a short samp. period to be used. In the HOLD mode,IssC is zero a. so the voltage on CI should remain f ixed. Thecircuit is in fact an analogue memory. It is used in musicsynthesisers (to remember the pitch). in analogue to digitalconverters and many other circuits.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
FEATURE: 3080 Circuits
MANFRED FilfAt L 12V
NOUL
4 Quadrant MultiplierThe CA3080 is a two quadrant multiplier but. with the additionof a few extra bits of electronics. it can be made into a fourquadrent circuit. A two quadrant multiplier has two inputs,one can accept bipolar signals (the inverting or non inveninginput) and one can only accept a unipolar signal, (the Nomcurrent). However, a four quadrant multiplier can accept bipolarsignals on both of its inputs which enables it te PerfOrmfrequency doubling and ring modulation.
The circuit is fairly similar to thst of Me two quadrantmultiplier described earlier except for two differences. IC3 isused to generate lalIC in such a way that the Y input can go bothpositive and negative, thus the Y input is bipolar, when is at 0 V
KINN MOSS LATLON
and there is a signal on Me X input the desired ootpor(oo V)should be zero. This is achieved by adjusting RV, so that thesignal via ICI (this is inverted) is exactly cancelled out by that vieR3. Now. when is inc aaaaa d positively. a non -inverted value ofX is produced at the output and, when Y is increased negatively,an inverted value of X is produced. When I' a sem so le theoutput. This a known sometimes as ring modulation. if aspeech signal is connected to the X input and a variablefrequency oscillator to the Y input the resulting sound isthat of adalek.. Alm. if a sinewave is connected to both the X andinputs, the XY product is a sinewave of twice the frequency.This is known ace frequency doubler, but it will only work withsinewaves.
Single Pole FilterA singlepole lowpass filter can be constructed using a CA3080as a current controlled resistor. The filter is, in fact, just a simpleRC low pass section where the R. which is controllable, isconstructed out of ICI. RA 115. Varying Issc changes theamount of current drive to CI . This would normally make thecircuit a slew limiter, but because the signal level that ICI (pins 2
PONES. f ROM, In
and 3) handles is so small. the CA3080 works in ma linear modeThis enebles it to look like a variable resistor. When Mrs resistorIS varied. the break 'frequency of the f Met also raniaa Srapplying some positive feedback around the filter Re. C2 npossible to produce a peaky filter response Themcreases with frequency 'making the circuit useful a guitar
WM Wah unit.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979-0
FEATURE: 3080 Circuits
Voltage Controlled Filter
A tandard dual integrator filter can be constructed using a fewCA3080.s. By varying Ines the resonant frequency can be swept
o r a 1000 to 1 range. ICI, 3 are two current controlledi rygretors. IC2, 4 are voltage followers which serve to buffer
rs
FIRFOLIE
the high impedance output of the integrators. A third CA3080(ICS) is used to control the CI factor of the filter. °factors as ighas SO can be obtained. The resonant frequency of the filter islinearly proportional to Icac and hence this unit is very useful inelectronic music production. There are two outputs produc d. alow pass and a band pass response. ETI
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ELECTRONICS TODAY INTERNATIONAL -APRIL 1979
TRADINGAT411
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LECTRON.S. TODAY INTERN,IONAL - APRIL 1979
iftegkrElit,
microfileGary Evans looks at PET add-ons, a Simon that's not simple and has news ansuperboasd
has to date heon nor', s.spporn,the PET
numPer ol companies have stepped into the voidcaused hv ma of commodore periPherMs evervthirM homRS232 interfaces to PE I compatahm floppy drives are
about iocnange
PFSem hut f II outtule sg;ol'tne21===!nt"i71:1:" 111 allow 360K 13two standar:5,in Disk driverVu'q':751/'370r;Vs'is.accomplished without msortinq to double uaciung ordouble density This is achieved line re not told exactly
'fiZen'orZeXTC's=r1r2F140"4 a" 65°2 - a"may be used 38 tracks with a constant density recordingr,:ach track provide 171820 bytes for user stamp per
The 2.0 requites only one connection to dm VET anintertatecord connect, ele mut to PET s IEEE port
'cea'fcluu ''' 4,"="rtn: ;Kfs:Ters.sientcropc?sms or Tne 81('2001 8 m mom ro mave room lor,thelarge, keyboard Me intepralcasscm oem, nes o,enoz,t%
anct a seP ..... deck wdl nave ic ee ov.mvet
'"rhde',113rTns due m Amer vermons
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.1'hasF7t1r.nat:ed'11:12%171"0'Pes'latFin:'tnnhe:gis:al'in'asn'i:Farrn'Sam''
mance
NEWS
Toying WilM1 MPUs
Super Ohio
ET1
Back numbersNatoaback. sssss of ETI Iwo available Inc.are not than well The table below ehcoPI. coo be obtoMod Nom ourcosts 60p Inc pOp and m
1976 /977 1976 1975 1970 1973 1972No! Not Nol No!Nol o!
alarch No! NW No,. o! NoI NW NW
Yo.roVe "W No! rPrgl rPtJuN Nol No! NolAug Not Nol No! No! NolSept No, NW Not No! No!Oct No, NoI Nol NW No,N. NW NO NO NW NW NWDeo NW NO NW NW NW NW
Photocopies of any artiale Nam arty one issue are
ALL INVOICES, ENQUIRIES, ETC., TO
OUR TEMPORARY ADDRESS OF
cmia.-irmiziik Ell LTDNORWOOD ROAD
READING
TELEPHONE NO. READING 65916
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WHAT'S IN THE APRIL ISSUE
COMPUTERSURVEYThe number ol small systems on
Vet [IC Vs't7eian Znet7n1Peot a machnte to suit your appliedtion.The April issue at ComputingToday surveys some ol the more
's7fori===.7sdslir:;
NASCOMADD ONST. NASOOM I computer hasbeen one ol the most success.ol the MY computer kits on Memarket recently IVASCOM ;nerdduced number ol extras Metallow the basic ...es poten-tial to be °onside.. enhancedWe take a look at the expansion
PLVD:offering.
EXPANDA PETT. commodore PET has beenwin, us Mr over year now butperipherals Mr the computer hambmn slow to appear. One ot theessential devices in many ...-no. is a floppy disk to pr.. asystem ol mass storege thattaster in operation .n the Wmsystem of the star.. inwhine
'Otnp :I= Is7 dr;:e's7;mon operatMg system thee wMProg straight,. your PET
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AMBUSH GAMEThe April issue of our six. that will .now those of you whomagazine, ETI, carries project don't dabble in electronics Mpleycalled Ambush. Ambush is an Ambush on your computer
CONSUMERSHOWThe recent Winter ConsumerElectronic Show in Las Vegas saw
MITZ:rro"d ugs TnfChew challenger Mat talksGerald Chevin was Mere lot Com.pitting Today and his reportappears in the April lassie.
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PROJECT
WIND METERHere is the project all you amateur meteorologists have been waiting for. When thismeter gets the wind up you'll know how fast and where it's coming from.
TRADITIONALLY, THE FOURprimary elements are fire, earth,water and air. At ETI, we'vedesigned projects concerned with thefirst three (temperature meters. soilmoisture indicators, rain alarms). butnot much for the last. The majorproperty of the air, apart from thefact that it is necessary to supportlife, is the movement of the air -wind. Light winds generally aren't ofterribly much significance except tometeorologists, but stronger windscan be useful as a source of power:for traditional milling, for electricitygeneration or as a means ofpropulsion for sailing yachts.Stronger winds such as hurricanes,can be destructive, causing damageto life or property.
So for all the private pilots,yachtsmen, amateur meteorologistsand general weather watchers whoread ET!. here is a device which willtell you the wind's speed anddirection, with a remote indication ofboth quantities. Our design is, we'dlike to think, both stylish andunusual, but there are simplermethods of mechanical constructionwhich you can follow if you wish.
The HeadThe drawings along with the photoswill give the general design that weused. The actual dimensions have tobe left to the individual constructoras components such as the ball racesand light bulbs may vary in size.
While we used a single head forboth speed and direction, it may besimpler to use separate heads.
The discs we used were 1.5mmthick clear plastic with a piece ofphotographic film glued onto it. Itmay be easier to make it out of thinaluminium and cut out the slots. Forthe speed disc simply drilling holeswill suffice.
The most important part of thedesign, apart from ensuring that thediscs rotate with a minimum offriction, is the shielding of the lightand preventing light scatter striking a
A/11\113 METER0
transistor which should be dark. Ascan be seen from the photos anddiagram the bulbs and transistors areembedded in aluminium blocks withsmall holes providing a passage forthe light beam.
The wiring of the head is shown infig. 3. Note that the base lead is notused and can be cut off close to thebody. Insulate the joints onto thetransistors to ensure that they do notshort on the aluminium blocks. Thebulbs may touch the block with theirouter connection but this is the 0 voltline and does no harm. In fact itprovides some electrical shielding farthe leads. The bulbs we used were12V but they were bright enough on6V giving a much longer life.
Design FeaturesWhen we started design on thisproject it was to have a digital
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
readout of wind direction with aresolution of either one or twodegrees. This would also make ituseful in a sailing boat to tell thewind direction relative to theheading
Difficulties however soon becameapparent. The first of these was thesensor head. The only accuratemethod is a digital head, probablyoptical. Two methods could havebeen used, one using a disc with asingle optical track of 360 slots andan updown counter and the secondusing eight or nine tracks in a greycode. The first is simpler in headdesign but the second is less proneto error. The problem, and thereason for rejecting both, is that withsuch resolution, the reading wouldmove around so much when thewind is gusty to be unreadable. Whatis needed is an averaging circuitwhich unfortunately becomes
85
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Fig. 1. Complete circuit diagram of the ETI Wind Mom
difficult when the wind is changingfrom just west of north to just east ofnorth. i.e. 355 to 005. How do youaverage these (use amicroprocessor?)_
As this was intended to be asimple project we relaxed ouroriginal speification, deleting the usein a boat (we may get back to this.problem. A four track 'Grey scaleallows the wind to be given to within11. of its true heading, without thecomplexity of a nine track one, andthe use of LEDs to give directionsolves the problem of averaging asthe variations can be seen andaveraged by the brain.
86
d I
15
ConstructionThe electronics is relatively simpleprovided the PCB described is used.Due to a height limitation C1 shouldbe mounted an the rear of the board.The LEDs should be mounted about7mm from the board with care beingtaken not to damage them as theleads have to be bent out slightly.The regulator also has to lie down togive clearance.
We mounted the unit behind analuminium front panel with the LEDsprotruding through holes. If this is tobe done it is preferable not to solderthe LEDs until after alignment with
6060
ovov
the front panel.The head is more difficult as some
mechanical ability is necessary toensure good results. Therequirements are basically simple Adisc is to be allowed to rotate. eithercontinuously with the wind oraligning it to the wind, with a bulbon one side and phototransistors onthe other.
The method used by us is shownin fig 4 with the aluminium blocksproviding the shielding necessary togive accurate results. As the unit willbe exposed to the weather it must bemade waterproof otherwise the ballraces will corrode. The races used
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
PROJECT: Wind Meter
HOW ITWORKS
Wind DirectionWind direction is indicated bye series of 16equally spaced LEDs around a circle. Theserepresent the main points on the compass.These are controlled by ICI and whichare in barn controlled by the directionsensor head.
The sensor head. which is described infig. 3. consists of a disc which has fouroptical tracks and four bulbs and photo -transistors. The phototransistors senseeither a clear disc (logical ..1.) or a blackdisc (logical '11") and thus control IC2 andICC. The code used n special in that onlyone bit is changed at each locationLing gross errors which occur with thebinary code if the heads are not perfectlyaligned. An example of this is going fromlocation i (MI I) to location g (WOO). It thisis not done simultaneously almost anylocation can be specified. With the greycode the same change 15 from 01W to I WO.Here there can be no ambiguity as only onebit is changed. Remember these bits are notweighted similarly to binary and a lookuptable must be used to decide what number(decimal) a particular code in.
The decoder, CO. is an eight outputanalogue demukiplexer with the commonline joined to the +5V line. When a parti.cuiar 3 bit code is presented to its controlinputs one of the eight outputs will bejoined to the .h6V line. The fourth outputfrom the sensor head controlsgives two. inverted. outputs to drive eitherbank of LEDs. The complete four hit cod,therefore specifies a particular LEO to belit. By placing the LEDs correct, aroundthe circle the grey code is decoded.
Wind SpeedThis is a simple frequency counter mea swing pulses from the sensor head. Thehead consists of a disc with eight holeswhichbreaksa light beam to its associatedphototrarisistor. The output of this photo.transistor is squared nob,: a schmitt triggerformed by IC5c. and ICS&
The counting is done by IC,. and IChb(adual decade counter, with 1(16 and IC'providing the store and LEI, driversnecessary to diler the seven segmentplay TiMe base Is provided by IC3 whichgives a 7 rnS wide negative pulse aboutevery one second We say about as it isadjustable by RV: as individual heads willhave different responses and calibrationwill be necessary.
This negative pulse opens the store toallow the number reached by the countersto be displayed while simultaneously stop-ping any further counting by disabling thewhinitt nigger. On the completion of the7mb pulse IC5a. and IC5b generate a 5000wide pumlse which resets the counter ICs torecomence the sequence.
Power SupplyThis is imply' a full wave rectified supplywith ICI giving a regulated +6V outputThis regulation is needed to ensure that thetime base (1C3lrernains accurate.
The finished unit in use
ELECTRONICS TLOT,'.AL-APRIL IS%9
toI'
TO TRANSFORMER
ACAC I I I CT
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LED9=D- cui
TO 01 4h0,020 LE'l
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Fig. 2. Component overlay for the Wind Meter
PARTS LIST
TO Q3
TO Q2-44 1 111-TO 04
9--
OSP 1
RESISTORS all 466 544. SEMICONDUCTORS81.4,8.9 10k CI 78061166,13-26 6800 IC? 405107,10.12 100k IC3 555R11 470k 1C4 5 4011
IC6 7 4511IC8 4518
/POTENTIOMETER
01-05 2057701.2 104004
901 1M Ihrnmmor LED TIL 209 or Streliar0141112111.2Common cathodeseven segment (high
CAPACITORS bughtness1C1 1000u 16VC2.6 10u 25V MISCELLANEOUSC3 tu 25V Four rernorture 12V bulbs. PC8L 240V!C4.5 8206 ceramic 18.1 transformer box head assembly
88
k
LED10
16
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ICI
I I I
LED1 C2
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or
Fig. 3, Connection to the bead. Note(' -4.that transistor bases are not used.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
If
PROJECT: Wind Meter
[hemmed in the sensor head -1.5 mm thick, clear plastic with photographicfilm glued on.
Fig. 4. Mechanical construction of thesensor head.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
will normally have to be washed outto give low enough friction with alight spray of WD40 or similar togive some protection.
While our housing is a littleornate, it did work but the moreusual half ping pong balls may bemore suitable.
CalibrationWind Speed.The easiest method for wind speedcalibration is to provide the unit witha DC supply (via the common andone of the AC inputs) and to take adrive in the car with the unitsupported above the vehicle.Providing there is no wind thepotentiometer should be adjusteduntil the reading corresponds to thespeedo.
Direction alignment is simply amatter of aligning the vertical rod sothat it gives the correct results.
EnBUYLINES
The metalwork for this project wemust leave to our readers, as this willbe fabricated to suit individualrequirements. The displays can beany type no's really, lust observe
Similarly with the LEDs. Thephotodarlingtons can be supplied byMarshalls.
as
'7421r
Now It Works -AM/FM
DOUBLEDICE
Zsrav7aunvo've7r211=3;doling,swihable odds to allow
tZle'llard'crotnrrtrIV:gn.mek:;lite easier and overall we think its anice on,
See what you think next month.
Atte.
HEADPHONEAMPLIFIERA prohect to warm the ears and please the rem of the universe. ased on ahigh quality Class A design, this unit provides hi-fi drive Mr one or morePairs of dynamic headphone, allowing you to wallow within an undimneared mund field. and leaves everyone around free to do their own thingwithout having to listen to yours.
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1.3.4Y INTERNATIONAL -APRIL 197
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ELECTRON CS,
PROJECT
GUITAREFFECTS
UNITOur guitar effects unit isn't just a fuzz box. Use it to give you a new sound to playwith.
BUYLINES
The only component that may bedifficult to find ,s the .56 iEt
aupply this IC
ect A depth cont. allows
bypass sw.tch
Smashing sound
The luridarnentatency ol the input is NH waveed but the numerous hamonics
ult. sounds raffia/ like
.we don 0 vou no doubt Findmany mom musical uses tor thisele than we could
Swct itching between Fuzz enet suuzz
llin:vpt'c'hulon.s purpme
PARTS LIST
RESISTORS All 516 'ASV)
6602R2 686R3 27OR84.6.10. 11, 12 104AS: 383Al 100kRS 39kMS 820R813 14 lB
POTENTIOMETERSRVIIMOCAPACITORS
1110 elactroptsc5600 Pol18Vmne
SEMICONDUCTORSBC1097415358
01.2 1144148
SWITCHESSW1 SPOT SomswachSW2 SPOTSW2 DPDT
MISCELLANEOUS
Two Sm. mono lack socketsPCBVerocase MN
98
RV1
Fig.1. (above) PCB component ave.,'
(Above right) Completed PCB
Fig.2. (Below) Circuit diagram
ELECTRONICS TODAY INTERNATIONAL - APHIL 1979
/I\
cocana,
LOOK!
NAS COMOWNERSNASCOM 1
USERSHARDWARE
Keyboard Repeat (vari-able speed) £3.50
NoiseBox (make music)£350
SOFTWAREProgrammes for theNASCOM (can yours earn
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doeumemationS.A.E. for further details
READY -BUILTNASCOMs nee
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ZSOFTY .s equivalent to DevelopmentSystems costing thousands of pounds. YetSOFTY only costs you for kit and fullinstructions - £99.95 + 8% VAT. built andtested - £145 , 8 .: VAT 77.";77' =`.°. -
NASCOM 1 ..=05£165
-7.----........ t - Superboard IIFell BRI::::44 ow RAM
.... ...... £263.84......,
ASTEC SWITCH MODE ASTEC 12" II/WHITER
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£16.50ASSEMBLED 8 TESTED
£22.50
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MAW DM. WITH OLIPIZTE
E.27.80
12-HIRSTION CHARMSALARM
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KRAMER LCD.
1.-1.11711"5
ETCH RESIST TRANSFERKIT SIZE 1 1
l'Arir1TVCA'C'E"""ACCESSORIES
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STOCIaRTVC=110 2170N ICS 0055 INTPRATiONAL - APRIL I Y
Readers' Circuits
Gentle Clock Alarm
I. Hill -Smith
RINGI RING! BUZZ! This is D LTCLANG! PIP PIP PIP!
There are gentler ways to wake up.This circuit provides an alarm whichbuilds up from being inaudible to loudover about one minute. As a result youare always woken by the minimumvolume required to wake you: a farmore comfortable experience than theusual trauma. The three multivibra-tors in cascade provide a signal likethe sound of a warbler telephone. AsC slowly charges through If a largerfraction of the signal is amplified bythe op amp producing a louder out-put.
Calculator Radio Alarm
T Corringham
This very simple circuit, used with aSinclair Cambridge Programmablecalculator. enables a transistor radioto be turned on after a predeterminedtime. (within the range of a fewseconds to five months).
None of the components are criti-cal. but the SCR should have a suf-
ficiently high voltage and currentrating for the radio used.
Ha transistor radio is used the SCRis connected in series with the battery,but if a cassette recorder/player isused it can be connected to theremote socket.
The LDR is placed above the lefthand three digits of the display. RV1 isadjusted so that the circuit is triggeredby '888' being displayed, but not bythe background light only.
Using the program given. the time
00010203
080607080910
in minutes of the required delay is putin and /RUN/ pressed to start thetiming period.
To stop the program prematurely/+/c/ CE/ is pressed.
The calculator should be used witha mains adaptor.
The timing is accurate to withinfive minutes in eight hours.
If a buzzer or similar alarm is usedthe same circuit can be used to givean audible indication of the termina-tion of long programs.
ELECTRONICS TODAY
prepare circuits or ideas submitted by readers or this page AO itemsused will be paid... Drawings should be as dear as possible and the text should p eeeeee sentrte typed. CirCuitS Meal not be subplot M copyright. Items for consideration should beto PTI.TECN-TIPS. Electronics Today I eeeeeee 25-27 Oxford St. London W111 .1R1F
103
Keyboard/display sound con-verterK G Reid
This circuit can be used in severalmodes: It can provide quantizedfeedback (a distinct improvementover the normal singie 'bleep') fromthe key actions made on a calculator -type keyboard It can be used to give a'sound' translation of a digital display,or completely replace the displaywhen sound would be a better com-munication medium.
The keyboard or display informa-tion (a maximum of 16 bits with one16 -line 74150 multiplexer) is trans-lated into a series of 16 high or lowfrequency tone pulses, correspondingto the 'high' or 'low' logic state of the16 bits.
The circuit illustrated was used inconjunction with a digital mulumeter,requiring three 4 -bit words for thedigits and three additional bits forover -range, negative and decimalpoint. Thus, 15 lines only were req-uired, the 16th being used for reset-ting
The 15 bits are latched on to theinputs of the 74150 multiplexer. Pre-sentation of the enable pulse results ina logic '1' appearing at the output ofgate 13, allowing clock pulses to passvia gates A and Fl to the 7493counter. Gates B, E, D and C form alatch which remains 'set' until all 15bits have been sampled. As each bit issampled, the inverse state appears atthe multiplexer output, opening gate
Readers' Circuits
J or K and thus operating one of thetwo reed relays. Asa count of 1111appears from the counter, the outputof F drops low, resetting the latch andcounter. The operation of either relayresults in a tone appearing at theloudspeaker (or earpiece), the tonefrequencies being set (1 2 kHz maxi-mum) by the 1 megohrn pots. Thetone pulse length is governed by theclock rate.
Digital Pulse Compressor
N C Hall
Whilst constructing a digitalfrequency meter the author found itnecessary to be able to accurately Fri m
.the width of a gate pulse. The circuit,shown uses only two ICs and can:reduce the width of a pulse applied atits input by up to a few milliseconds.The table shows the reductionachieved by using different values ofCl.
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979 105
PRINTED CIRCUIT BOARDS andTAMTRONIK LTD. [DEPT. ETO KITS FOR ETI PROJECTS
ADOITIONAE PRINTED CIRCUIT BOARDS
SYSTEM GB NITS WITII A PROFESSIONAL FINISH
SPECTRUM ANALYSER. ALARM
7,42
RAils tan be supplied excluding h andFor cse, Send sae tordetails naming 101,,I Mt reference and catalogue P 13. P. 30p r;LNe_.. mcm
Trmle nod Ed1114.01131 ermumes welcome West MidIrd," -
a digitizer adds another dimension
Readers'Circuits
Darlington Drivers for a fewpence
C. J. Ramey
This circuit offers a very efficient wayof driving a pair of transistors in Dar-lington configuration from CMOS.The circuit in Fig 1 shows how twoloads of up to 1A may be driven froma single 14007 chip with no externalresistors. Using a 2N3055 in place of
will enable loads of up to3A to be driven at voltages limitedonly by the Vceo of the transistors(WO.
Fig_ 2 shows the internal circuit ofone section of the 14007. A high on
pin 6 switches the lower CMOS tran-sistor on, holding Q2 off and sinkingthe leakage current of Ql. A low onpin 6 drives Q1 and switches thelower CMOS transistor off and theupper CMOS transistor on.
The result is fast switch off at lowcost and efficient switch on.
A bonus is the Inverter betweenpins 10 and 12 Note, Vcc should be5-6V to prevent excessive currentbeing drawn from the CMOS chip.
Precision Rectifying with theLM3900
A. Winsor
The LM3900 is different from mostop -amps in that it is current differen-cing and operates from a single sup-ply rail, which mean that the inputsbias at one base -emitter voltage aboveground. Hence standard techniquesare not applicable as the diode wouldalways be forward -biased. Two feed -
NOTE.back paths are therefore provided:-R3 for DC stability, and R4 for the AC EF,441"`"°'signal after C2 and R5 have filteredout the DC bias. When R2 , 2 X R3 made very much smaller than R3. Cl ments.point A will be at Vcc/ 2, allowing the and C3 are DC blocking capacitors _This circuit has obvious potential,diode to be reversed at will. For large and determine the low frequency roll- especially in portable equipmentpositive input returned to ground. off. Component values quoted are where the 4 amps. in one packageInput impedance equals R1, and vol- those used on the prototype and may and single supply rail yield a more,tape gain equals - R4/ R1 since R4 is be altered to suit individual require- compact. mote convenient L9,
ELECTRONICS TODAY INTERNATIONAL - APRIL 1979 107
Here's whyyou should buyan ICE instead
of just anymultimeter
enthuronts, luesey,sts, senaceengrneers.*Worldwele proven reliability.*Lowsenscrog costsPA SOK volt sinsetwity and boob accuracy.*Large minorscele meter.*Fully protected NNW., FlYnnl&PA*Large range oi inexpensive accessories,*12 month wewents.bactrecl by a lull alter
sales service at E,B.Sole U K.DistributOrS,
Prices from £16.60 -£32.00 + VAT
LL.F.4f41.911514M LIAAITEL71
1-1
108
AT LAST!
The new Strethand Seco, Division cata-logue s here, Full deterls of alarm Cireuitprincipals and practice
How the prof esslonalf keep burglars at bey
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OSCILLOSCOPE sorstaiiiresurtFEATURES
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ELECTRONICS TODAY INTERNATIONAL - -
Understanding Digital ElectronicsNew teach -yourself courses
MN.IMOtal halms
8sa
4,17:0'7T,
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£4.601£12.00 -
Flow Charts & Algorithms
£2.95
PCB FOIL PATTERNSGATHERED HERE are all the PCBs for this month's symbol, the designer retains that Copyright to himself soprojects. From now on the boards will be grouped his company, and that particular board may not betogether like this in order to facilitate their use by those produced on a commercial basisreaders wishing to produce their own PCBs from these These pages form the basis of our ETI PR INT sheetspatterns. which are etch resistant transfers of the loll panerns
All are shown foil side Lip, and full size. Companies designed to simplify one-off PCB production See the adwishing to produce these for sale as ready made PCBs on page 49 for further detailsshould note that where the board carries a copyright
110 ELECTRONICS TODAY INTERNATIONAL - APRIL 1979
PCB Foil Patterns
Below left: Wind Speed Indicator PCBBelow right: Click Eliminator Mk 2 boardRight: Struzz effects unitAll are shown full size and will form the basis of ETIPII INTsheet 023 which will be available shortly
ELECTRONICS TODAY INTERNATIONAL- APRIL 1979
0 0
1IdLL kF2ML.41"
424740 E GUITAR EFFECTS
MINI -ADS & CLASSIFIED
MICROBITS
,:0dren..1 TV)
l:lesse telephone for demons tr
Ir A limited number ex.edockotherwise 7-14 dev
R"'GredeerleySURREYTel 0276 34004
P & R TESTARE HAVING
A SALESTARTING
10th MARCH1979
FORT WEEKSATURDAY AND
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ire4:4:TV:11,76
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BRITISHMOTOROLA
61100 SYSTEMS
rvifigiFrBARGAINS FOR THE
ELECTRONIC HANDYMANBRANDED LED DIGITAL
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SC/MP USERS60r/o OFF
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"agraggrTEL 102221 40 DOS
CCCAT M
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£99.99= ABEST OFFER EVERCamara Kit, Lens,Vidicon H. Modulator
CROFTONTel: 01-8911923 Frer.,:e
THIS SECTION IS A PRE -PAYMENT SERVICE ONLYM041 -ADS 31 4'. 211,1.30.6-11 035 13 313m33.034 IRpper word. Minanuen 35 wo.d Boxed classof. E 33 .CLA"'""'""'las accept. *out NU stldnso .."
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INTERESTEDIN HOMECOMPUTING?
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TRS 80 & APPLE II USERS44
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IRS 80 SOFTWARE NEW100 MIXED PROGRAMMES £49.00on cassette
SHORT C12 CASSETTESto ror £4.00FOR COMPUTER PROGRAMMES
TV GAME BARGAINS ,,,a4=r.
ATARI VIDEO SYSTEMREDucED To cu. VAT
KEY BOARD758 GEORGE RISK
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lot79 key
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EXIDY SORCERER 32K RAM computer £850
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0 Plug .in ROM facility leg 8K BASIC, (supplied). 12' Video monitor £69Assembleneditor. word processing etc.) so that you 5100 expans
andMotherboardand power SuP0tYl £210
DISK SYSTEM as shownMICROPOLIS 5100 disks - 315 K bytes per driveDrive 1 (includes S100 controller.Micropolis M DOS and BASIC software) £649Additional 315 K bytes drives (up to 4 per controller) £349Cables and regulators for 2 disk system £41
ADDITIONAL SOFTWARE FORSORCERER PLUS DISK SYSTEMCPIM operating system £145CPIM with C BASIC (Compiler/Interpreter) £235
FORTRAN 80 £350
COBOL 80 £490
PRINTER as shown MICROPOLIS STOCK CONTROL (INVENTORY)
ANADEX DP11000BASIC PAYROLL £99
80 columns. 112 char/sec 5 e 7 dot metric headPACKAGES ACCOUNTS RECEIVABLE eachFROM
LEDGERConnects to parallel or serial ports E576 COMPUMAX PERSONNEL
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