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E L E C T R I C A L P R I N C I P L E S
93
Number in Counter
0
1
2 3
4
5 6
7
8
9
0,
\
l a t . T r i g g e r
@
0 X
0
X
0 X
0 X 0 X
0 ' \
/
4 t h . Trigger
@
0
0
0
0 0
0
0
0 X
X
O(
\
Code
0
1
2
1
4
1
2
1
8
1
0
E
a
r
r
~
2
4
4
2
8
4
Ncte
- X
Indicates
Trigger
ON
0
Indicates Trigger
OFF
Figure 91. Electronic Counter Chart
carry to the left is effected each time a position of
the counter changes from 9 t o
O.
T w o tubes are
required for carrying from each counter position
except the last. A trigger is turned
ON
when the
counter advances from 9 to
O.
The trigger con-
ditions a switch tube to permit a carry impulse ro
be fed to the next higher order counter position.
If the position receiving the carry impulse stands
the carry impulse is of sufficient duration to com-
plete the carry to all counter positions if necessary.
The carry impulse is made available after the add-
ing portion of the cycle, and the carry triggers
that have been turned
ON
are restored to the
OFF
position at the completion of carry.
The carry
operation is shown in block diagram form in Fig-
ure 92.
The details of the carry circuit are des-
cribed in a la,ter section after the computing cir-
cuits have been described.
Pulses may be delivered to a counter at the com-
paratively slow rate of card cycle point timing, or
dt the 3
5.000
cycle per second rate as in the case
of counter transfers. Counters have been success-
fully operated at impulse rates up to 1 IO,OOO cycles
per second. The impulse admittance is controlled
by tube switches, to be described later.
A detailed explanation of the operation of one
position of an electronic counter circuit is pre-
.
sented below (Figure 9 0 ) .
Triode
B
has its grid connected between the
u
at 9 and advances to 0, its carry trigger is turned
anode of tube
1
of trigger
8
and the -100 volr line
ON
to condition the switch and continue the carry
by means of a voltage divider
RIR2.
The anode of
to the next higher counter position.
The carry is
tube 1 of trigger
8
is at
+
40 volts as long as trig-
not instantaneous t o two or more positions, but
ger
8
is
OFF.
(See discussion of Trigger Circzrits.)
Carry
Control
Suppressor
---------
i
I
Control
?
Input
Counter
Pulses
Position I
Corry
Suppressor
I
---------
1
I
Control
Position 2
Carry
Figure
92.
Block Diagram o f Carry Controls
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