HP AC-4A Supplement
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'TIO:N'"
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•
------------
•
APPLICATION
NOTE
4
<5/)
MODEL
AC-4A
DECADE
COUNTER
CONTENTS:
A.
Block
Diagram
of
Simple
Electronic
Counter.
B.
AC-4A
in
Basic
Electronic
Counter
Circuit.
C.
Driving
Circuit
for
AC-4A.
D.
Remote
Readout
Circuits
for
Use
with
AC-4A.
E.
Reset
Circuits
for
Use
with
AC-4A
•
HEWLETT
-PACKARD COMPANY •
1501
PAGE
MILL ROAD • PALO ALTO, CALIFORNIA, U. S. A.
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..
•
•
A.
BLOCK
DIAGRAM
OF
SIMPLE
ELECTRONIC
COUNTER
AMPLITUDE
IN
PUT0--
'
GATE
DISCRIMINATOR
_,.
'I/
AC-4A
AC-4A AC-4A
AC-4A
J
J
,,
' '
"-
-
THOUSANDS HUNDREDS
TENS
UNITS
1\
1"\
I"\
1"\
RESET
Fig.
1.
Block
Diagram
of
Basic
Electronic
Counter
Fig.
1
is
a
block
diagram
of
an
electronic
counter,
which
consists
of
the
following
sections:
AMPLITUDE
DISCRIMINATOR,
which
connects
to
the
INPUT
voltage
to
be
counted.
Fr
om
this
signal
input,
which
m ay
be
a
sine
wave,
square
wave,
or
pulse,
the
Amplitude
Discriminator
develops
the
required
driving
pulse
for
the
first
AC-4A
Decade
Counter.
The
output
pulse
of
the
Amplitude
Dis-
criminator
is
of
the
same
amplitude
and
rise
time
regardless
of
the
amplitude
and
rise
time
of
the
signal
to
the
INPUT.
GATE,
which
in
its
simplest
form
is
an
ON-OFF
switch
connected
between
the
output
of
the
Ampli-
tude
Discriminator
and
the
first
AC-4A
Decade
-1-
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Counter
.
The
Amplitude
Discriminator
puts
out
pulses
as
long
as
it
receives
an
input
of
sufficient
amplitude;
however,
pulses
cannot
operate
the
AC
-4A
Decade
Counters
unless
the
GATE
is
open.
This
GATE
may
be
a
simple
ON-O
FF
switch
as
shown
in
F
ig.
2,
a
pair
of
relay
contacts,
a
vacuum
tube
biased
in
and
out
of
cut-off,
a
diode
arrange-
ment
or
other
circuit
configuration,
depending
upon
the
speed
and
accurac
y
requirements
placed
on
the
GATE
by
the
application.
AC-4A
DECADE
COU
N
TERS,
which
count
all
pulses
from
the
Amplitude
Discriminator
when
the
GATE
1s
O
PEN.
When
the
GATE
is
CLOSED,
the
AC-4A's
remain
indefi.nitely
on
the
last
count
received
and
display
the
total
as
one
numeral
in
each
decade
illuminated
b y a
neon
lamp.
The
output
of
one
AC
-4A
Decade
Counter
will
drive
the
input
of
the
next
without
additional
circuitry.
RESET
.
It
is
usually
desirable
to
return
all
AC-4A
1
s
to
zero
before
beginning
a
new
count.
All
AC-4A
1
s
can
be
reset
to
zero
s i
multaneously
with
a
RESET
switch
as
shown
in
F
ig.
2,
or
in
automatic
counting
equipment
this
can
be
done
with
a
thyratron
circuit
as
shown
in
Fig.
8 or F
ig.
9.
-2-
'
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•
•
•
INPUT
+210
REGULATED
Rl2
2
0K
-1
05
REGULATED
y
X
SENSITIVITY
GATE
0
CLOSED
j)f---~O~U~T~P~U~T_N~0~
-
~1
______
__,0--
◄
0
OPEN
AMPLITUDE DISCRIMINATOR
522B-58-1
OUTPUT
N0
.2 INPUT
TO
1ST
AC-4A
TO
NEXT
-------,f,;.,,(4Jlr.,'°"-------m,
AC-4A
DECADE
COUNTER
IF
USED
BLK.- R
BLK.-Y
BLK.
-G
BLI<.-
X y
PRESS TO
RESET
15K
IOW
3-
115V
65MA
SELENIUM
RECTIFIER
X y
Rl3
IOW
250
!1
X y
X
6 H
IOO
MA
*
'-<-------<>+
300
y
PHOTO TUBE
VOLTAGE
---"·"'
'v------------0
-
I
05
REG ULATEO
5.
6K
2W
- NO
TE
-
Adjust
the
value
of
Rl3
for
+300
volts
output
from
power
supply
under
load.
Fig.
2.
Simple
Electronic
Counter
Using
the
522B-58B
Ampl
i
tude
Discriminator
to
Drive
the
AC-4A
Decade
Counter
Units
-3-
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AC-4A
IN
BASIC
COUNTER
CIRCUIT
Fig
2
is
a
schematic
circuit
of
the
counter
in
Fig.
1.
The
Amp-
litude
Discriminator
can
be
built
following
the
circuit
in
Fig.
3
(Schematic
Diagram
Amplitude
Discriminator
Unit
for
Model
522A/B
)_
This
Amplitude
Discriminator
is
available
from
Hewlett-
Packard
Company
as
a
plug-in
unit
-hp-
Part
No.
522B
-58B.
The
GATE
is
a
manually
operated
switch
but
could
be
a
pair
of
relay
contacts
.
Counters
are
RESET
to
zero
with
a
manual
pushbutton.
The
power
supply
should
be
able
to
furnish
+300
volts
at
15
ma
and
6.
3v
ac
at
1.
2
amps
for
each
AC-4A
used,
in
addition
to
+2
l0v
regulated
at
10
ma,
-10
5v
regulated
at
3
ma,
and
6.
3v
at
. 6
amp
for
the
Amplitude
Discriminator.
This
counter
will
count
at
a
maximum
rate
of
120
kc
or
more
and
the
total
number
of
digits
displayed
is
limited
only
by
the
number
of
AC
-4A
Is
used.
To
adjust
Rl2:
a.
Connect
a
1000
cps
sine
wave
to
the
input
of
the
Amplitude
Discriminator
(Fig.
2).
b.
Observe
the
output
at
Pin
1
with
a
scope
or
ob-
serve
the
AC-4A
Counters
for
steady
operation.
c.
Decrease
amplitude
of
1000
cps
input.
d.
Adjust
Rl2
for
a
symmetrical
square
wave
or
for
steady
operation
of
the
AC
-4A
Counters.
e.
Repeat
above
steps
until
the
minimum
input
voltage
is
reached.
f.
This
is
the
correct
setting
of
the
sensitivity
control
for
best
operation
at
all
input
voltages
and
frequen-
cies.
-4-
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•
•
•
-t-200
R5 R II
15 K V2 1
5K
5 9 6 3
OUTPUT
OUT
PUT
C2
R6
RI
O C4
22
47 K
47
K
22
7
INPUT
4,5
B r
VI
V2
9
OU
TP
UT
OUTPUT
SCHEMATIC
DIAGRAM
AMPLITUDE
DISCRIMINATOR
UNIT
®
STOCK NUMBER
5228-58-8
F
igure
3.
-5-
COPYRIGHT 1
95
4 BY HE
WLETT
-R\CKARO
CO
MPAN
Y
Thi~ dra
wi
nQ
rs
intended for
t
he
op
!r
ofion
and
ma
intenan
ce
at Hew
lett-Pack
ard equ
ip
ment
and i5 not
to
be
use
d
other
wise or
reprod uced without
wr
itt
en
co
nse
nt
of
the
Hew
lett
-Packard
Co
mp
any.
www.SteamPoweredRadio.Com
C.
DRIVING
CIRCUIT
FOR
AC-4A
Triggering
of
the
Amplitude
Discriminator
is
at
the
approximate
de
levels
shown
below
when
connected
as
in
Fig.
2.
PLATE
Pin
I
V2
(Fig.
3)
is
normally
conducting
for
O
v
de
on
Pin
5
(INPUT)
of
the
522B
-58B
Amplitude
Dis
-
criminator.
PLATE
Pin
1
of
VZ
cuts
off
when
the
de
level
at
the
INPUT
crosses
approx.
-0.
4
volt
going
negative.
PLATE
Pin
1
of
VZ
conducts
again
when
the
de
level
at
the
INPUT
crosses
approx.
-0.
2
volts
going
positive
from
a
negative
peak.
An
AC
-4A
driven
from
this
Amplitude
Discriminator
will
count
at
"A"
if
driving
from
Pin
3,
at
"B"
if
driven
from
Pin
1
of
the
Amplitude
Discriminator.
Positive
de
levels
at
the
INPUT
(Pin
5)
WILL
NOT
trigger
this
discriminator.
An
attenuator
and
a
de
buck
out
voltage
can
be
used
in
the
input
circuit
of
the
Amplitude
Discriminator
if
it
is
desired
to
trigger
the
counter
at
some
particular
place
on
an
input
wave.
0
VI
I-
...J
0
- .2
>
0
0
-.4
Fig.
4.
Trigger
Levels
of
the
522B
-58B
Amplitude
Discriminator
Connected
as
in
Fig.
1
-6-
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D.
•
•
•
REMOTE
READOUT
CIRCUITS
FOR
USE
WITH
AC-4A
The
staircase
output
voltage
from
base
Pin
8
of
the
AC-4A
Decade
Counter
Units
is
a
de
voltage
proportional
to
the
digit
indicated
by
the
AC
-4A.
This
voltage
can
be
used
to
operate
printing
systems
using
coin-
cidence
detectors
or
can
be
read
out
on
remotely
located
de
meters
or
ink
:recorders
using
the
circuits
shown
in
Fig.
6
or
Fig.
7.
AC-4A
STAIRCASE
VOLTAGE
EQUIVALENT
CIRCUIT
PIN
8
PIN
6
Fig.
5.
Staircase
Equivalent
Circuit
Staircase
voltage
output
is
between
base
Pin
8
and
GND.
The
load
on
the
staircase
output,
including
a
short,
has
no
affect
on
operation
of
AC-4A
Counter.
Rg
-
Approx.
700k
V - +
135v
count
of
O
to
+55v
count
of
9
in
approximately
equal
steps.
Tolerance
on
any
step
is
±1
volt.
The
staircase
output
voltage
will
vary
with
the
unregulated
+300
volt
supply
to
the
AC-4A's
•
The
staircase
voltage
can
be
+55
volts
at
count
of
ZERO,
+135
volts
at
the
count
of
NINE
if
Rl
1,
Rl4,
R2
7,
and
R38
in
the
Sche
-
matic
Diagram
of
Model
AC-4A
Decade
Counter
are
all
changed
to
the
opposite
plate
in
each
binary
.
-7-
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•
1.
•
2.
3.
4.
5.
6.
•
50
4AMP
METER
+
Rl7
500K
+
♦
+135
APPROX
.
.---++300V
(PIN 4
OF
AC
-
4A)
47K
4
3
AC-4A
Rl6
20K
2
47K
0
PIN 6 PIN 8
680K
-
Fig.
7.
Remote
Readout
of
AC-4A
Decade
Counter
Unit
Usin
g a
Circuit
that
Supplies
a
DC
"Bucking"
Voltage
to
Permit
Use
of
a
Standard
Meter
Reset
AC-4A
to
ZERO.
Adjust
Rl6
for
O
reading
on
meter
.
Stop
AC-4A
on
9.
Adjust
Rl
7
for
full
scale
reading
on
meter.
Reset
AC-4A
to
ZERO.
Step
AC-4A
one
di
g
it
at
a
time
and
mark
meter
scale
.
-9-
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E.
RESET
CIRCUITS
FOR
USE
WITH
THE
AC-4A
In
automatic
electronic
counting
equipment
it
is
usually
desirable
to
reset
the
Decade
Counters
with
an
electrical
pulse
rather
than
with
a
manual
switch.
The
circuit
in
Fig.
8
will
reset
all
AC-4A
Decade
Counters
to
ZERO
simultaneously
if
a
positive
pulse
is
applied
to
the
INPUT
of
the
2D21
Reset
Thyratron.
Depressing
the
MANUAL
RESET
will
also
return
all
decade
to
ZERO.
47
INPUT
0-0------ill~-----A../\f\r----+-
_L_
Rl9
2MEG
-105
+200
6
.01
RESET PULSE
TO
AC-4A
( BASE Pl N
2)
_L_
470
MANUAL
RESET
Fig.
8.
Circuit
to
Reset
AC-4A
Decade
Counters
to
Zero
NOTE
A
positive
pulse
at
the
input
to
this
circuit
delivers
a
150
volt
positive
reset
pulse
with
fast
rise
and
slow
fall
to
reset
all
AC-4.A
Decade
Counters
to
ZERO
simultaneously.
This
circuit
will
function
if
Rl9
is
removed
and
Rl8
is
returned
to
approxi-
mately
-30
volts.
Smaller
negative
voltages
than
-30
will
enable
the
reset
thyratron
to
be
triggered
by
a
lower
amplitude
positive
pulse
but
will
also
make
it
more
susceptible
to
stray
pulses
from
other
circuits.
-10-
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\ 4 I
..>
•
•
•
Resetting
all
Decade
Counters
to
NINE
(or
more
properly
-1)
may
be
desirable
if
the
operation
of
a
gate
circuit
puts
an
extra
pulse
into
the
counter
circuits.
A
manual
pushbutton
used
with
this
circuit
should
be
connected
to
supply
a
positive
pulse
to
the
IN-
PUT
of
the
Reset
Thyratron.
680
INPUT
0>--------111---------"I
_j_
R21
470K
-195
+300
RESET PULSE
TO
AC-4A
(BASE PIN
2)
---y-
1000
IN34
500
Fig.
9.
Circuit
to
Reset
AC-4A
Decade
Counter
Units
to
Nine
NOTE:
A
positive
pulse
at
the
input
to
this
circuit
delivers
a
200
volt
negative
reset
pulse
with
fast
fall
and
slow
rise
to
reset
all
AC-4A
Decade
Counters
to
NINE
simultaneously.
This
circuit
will
function
if
R21
is
removed
and
R20
is
returned
to
approxi-
mately
-30
volts.
The
AC-4A
can
be
reset
to
NINE
with
a
manual
push-
button
if
the
leads
connecting
the
GND
and
RESET
buses
to
the
base
plug
are
reversed
where
they
join
the
printed
circuit
board.
Refer
to
the
reset
cir-
cuit
of
Fig.
8
for
details
.
-11 -
12/58
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