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E L E C T R I C A L P R I N C I P L E S
137
TO Anode 8 - 9 ,
To Grid of OFF
(Follower 8 - 3 ON)
side 8-16 Tr.
1 :
8-3OF F I
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Figure 124. Carry and Carry Control Circuit
The suppressor of BIT is connected to a voltage
divider between -2 50 volts and the anode of B92.
As long as B92 is conducting,
BIT
is cut off.
B1F
can conduct only if B92 is cut off. Since B9n fol-
lows the
OFF
side of trigger B3, B92 conducts as
long as
B3
is
OFF,
and is cut off as long as
B3
is
ON.
Consequently B92 is cut off from 10 through 14.
Since both the grid and suppressor of a switch must
be above cutoff to conduct,
B1
F
can conduct only
from 1 0 . 5 through 14, and the anode potential of
BIT is low from 1 0 . 5 through 14. Therefore B14
power tube is cut off from 1 0 . 5 through 14, and its
anode potential is high from 1 0 . 5 through 14.
Since the anode of B14 is connected to the top of a
voltage divider controlling the suppressors of all
carry switches, the suppressors of all carry switches
are above cutoff from 1 0 . 5 through 14.
At 14, all carry triggers must be turned
OFF
in
preparation for a new adding cycle. The negative
pulse at 14 is
by B8 power tube. B8 is
normally cut off since its grid is at approximately
-3 5 volts.
The grid of B8 is capacity coupled
through a 100 mmfd capacitor to B91 triode. B91
follows the
ON
side of trigger
B3;
hence, it pro-
duces a positive pulse at its anode whenever the
B3
trigger goes
OFF.
This positive pulse at 14 causes
B8 t o conduct momentarily, thereby producing a
negative pulse at its anode. Since the output from
B8 is taken from the midpoint of the load resistor,
the pulse produced is a -50 volt pulse. This -50
volt pulse at 14 is fed ro all the carry txiggers to
turn them
OFF.
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