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E L E C T R I C A L
P R I N C I P L E S
131
Figure 121.
Clipper and Inverter between Column Shift Switches end Product Counter
approximately +YO
volts.
This means that the
grid of 0-212 is at -25 volts as long as any of the
four switch tubes is conducting. When none of
the four switch rubes is conducting, the potential
a t the top of the .02 megohm resistor is approxi-
mately +I50 volts and the grid of 0-212 rises
above cutoff.
Consequently, as the negative
B
pulses appear at rhe load resistor, they are clipped
and appear at the anode of 0-212 as positive A
pulses, which are in turn applied to the grid of
inverter 0-211, where the process is repeated to
produce negative
B
pulses at the anode of 0-211.
The pulses at the anode of 0 - 2 11 are 100 volt
pulses, whereas a counter requires only YO volt
pulses. Therefore, the counters are fed from the
midpoint of the load resistors for the inverters.
Figure 122 shows a block diagram of the column
shift switch operation. The column shifr controls
in the
M
chassis are discussed in the following
paragraphs.
Tertiary Timer and Column Shift Control
As has been previously mentioned in connection
with the electronic timers, the tertiary timer con-
trols the column shift.
Each time the secondary
timer goes from 9 to 0, a negative pulse is passed
to the tertiary timer to advance it 1. The tertiary
timer is a conventional 3-stage binary counrer,
consequently it will count to
8
and then return
to O. Actually computation stops after rhe end of
the 6th column shift cycle, so the tertiary timer is
at
7
when the compuration is finished. The ter-
tiary timer is cancelled to 1, so that by observing
the indicator lights the column shift position can
be determined.
The circuits for ,the tertiary timer and all the
column shift controls are shown on the two sec-
tions of the M chassis. Section 1 of the M chassis
circuit shows the tertiary timer, its followers, and
the interpolating tubes.
Section 2 shows the col-
umn shift control power tubes and the switches
and power tubes for producing the pulses to feed
to the column shift switches.
The three triggers comprising the 3-stage ter-
tiary timer are MY, M3, and M2.
The indicator
lights in socket
M7
indicate the status of the ter-
tiary ,timer. Note that the input wire from the
secondary timer to the M Y trigger is shielded to
prevent undesired cable coupling to the grids of
M Y trigger. The two triode sections of M6 serve
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