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E L E C T R I C A L
P R I N C I P L E S
119
Ten-Pulse
Control
Up to the time the multiplier carries, no other
operation takes place. When a carry occurs, it is
a signal to start rolling the multiplicand counter.
Before discussing the multiplicand read-out, it is
necessary to establish the 10-pulse control circuit
together with its associated circuits.
Since several
of these circuits are interconnected, they will all
be discussed at this point.
First, consider the A33 switch tube (Section
24A) which produces negative pulses at 10 and
14 to turn trigger B3 (Section 27B)
O N
and
OFF.
The status of B3 trigger is indicated by indicator
light 5 on the socket B7.
The circuits for A33
and B3 are shown in Figure 1 12.
Switch A33 can conduct only when both the
grid and suppressor are above cutoff. The grid of
A33 is normally at about -35 volts and will rise
above cutoff when it receives a positive pulse from
tube A271 of trigger A27, the second stage of the
primary timer. This positive pulse will come every
time A27 goes ON, i.e., at 2, 6, 10, and 14 of each
primary cycle. However, the tube cannot conduct
unless the suppressor also rises above cutoff.
The
suppressor is directly coupled t o the anode of tube
A341, which is a follower for the
OFF
side of trig-
ger A29, the fourth stage of the primary timer.
As long as A29 is
OFF,
A341 is conducting, and its
anode potential is low (approximately
+
50 volts).
As long at A341 conducts, then the suppressor of
A33 is at approximately -50 volts which is below
cutoff for this element. When A29 goes
ON,
A341
stops conducting, and its anode potential rises to
approximately +I50 volts.
The suppressor A33
is then above cutoff, and conduction occurs
through A33 subject t o the pulses applied to the
grid.
Since the suppressor will be conditioned to
conduct by A341 from 8 through 0, of the four
pulses received by the grid, only two can cause
conduction, those at 10 and at 14.
When A33 conducts at 10 and at 14, it pro-
duces negative pulses at its anode. These negative
pulses are fed to both sides of trigger B3 from the
midpoint of the A33 load resistor. The -10 pulse
turns B3
ON,
which is initially
OFF
by cancelling.
The -14 pulse again turns B3
OFF.
Therefore B3
goes
ON
at 10 and
OFF
at 14 of each primary cycle.
Trigger B3 through its followers B91 and B92
controls several circuits among which is the 10-
pulse control. Follower B91 follows the
ON
side of
trigger B3 and thus produces a -10 pulse and +14
pulse. The purpose of these pulses will be explained
later.
Follower B92 follows the
OFF
side of B3;
consequently, it is conducting at all times except
from 1 O through 14. From 1 O through 14 the
anode potential of B92 is high to condition certain
switches. At 14 the negative pulse
at the
midpoint of the B92 load resistor is passed on to the
secondary timer to advance it 1 for each primary
cycle.
One of the switches conditioned by B92 is BIO,
as shown on the B chassis diagram (Section 28B)
and in Figure 113. In other words, B10 is recep-
tive to pulses applied to its suppressor from 10
through 14. A constant stream of B pulses is ap-
plied to the suppressor of BlO, and remembering
that B pulses are negative at index points and posi-
tive at mid-index points, it is obvious that B1O will
conduct on every positive B pulse from 10 through
14, or at 10.5, 11.5, 12.5, and. 13.5, as shown on
the timing chart in Figure 1 13. Before discussing
the purpose of these pulses, examine B4 switch
(Figure 113) which works with B10 switch to
control B16 trigger.
B4 also receives a constant
stream of B pulses at its suppressor, but its grid is
conditioned by A342, which is a follower for the
O N
side of trigger A29 (the fourth stage of the
primary timer). The anode of A342 is at high po-
tential as long as A29 is OFF, i.e., from O through
8; hence B4 switch is conditioned to conduct from
O
through 8 and will conduct on the positive shifts
of the B pulses at 0.5, 1.5, etc., through 7.5, as in-
dicated on the timing chart in Figure 113.
A t
each of these points a negative pulse is produced
at the anode of B4. This pulse is taken from a tap
on the load resistor of B4 and fed to the
OFF
side
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