HP AC-4A Supplement

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•
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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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•
•
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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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•
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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.

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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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+
..
Rl5
IMEG
PIN
6
-
4
3
AC-4A
2
0
PIN
8
R14
1.e
MEG
Fig.
6.
Remote
Readout
of
AC
-4A
Using
Ground
Return
for
Meter
1.
Reset
AC-4A
to
ZERO.
2.
Adjust
RlS
for
full
scale
deflection
of
meter.
3.
Step
AC
-4A
one
digit
at
a
time
and
mark
meter
scale.
-8-

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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-