G R 0
UPS
0 R
TIN
G
D.E
V
ICE
75
ing anode of the OA4G trigger tube. This positive po-
tential
is
available from the cathode of the previously
fired impulse storage tube and
is
applied through the
500K resistor, octal plug, emitter segment, and on to
the starting anode of the OA4G. This immediately
fires
the OA4G and sorts the detail card into the same
pocket
as
the preceding master card.
In
this manner,
all
successive
detail cards are sorted into the same pocket
as
the master card which preceded them.
Trailer Card Operation
Trailer cards are sorted in the same manner
as
are
the detail cards. Between
0 and 1 time in a trailer card
cycle, however, the trailer rail brush
senses
the corner
cut on the trailing edge of the card. This applies a
positive pulse
to
the control grid of the trailer card
control tube through commutator 4, the trailer rail
brush, the
.05
mfd capacitor and the 500K resistor.
The trailer card control tube
(2D21)
is
connected
across the
DC machine circuit in exactly the same man-
ner
as
the master card control tube.
It
is
also
biased in
the same manner.
Application of a positive pulse from the trailer card
rail brush cancels the negative grid
bias
on the TCC
tube, causing it to
fire
and pick up the TC relay. Pickup
of the TC relay opens the
TCR
points which break
the shunt circuit around commutator
3.
This places
the anode circuits of the impulse storage tubes directly
under control of commutator
3.
Therefore, when this
commutator breaks at the end of the trailer card cycle,
it de-ionizes any storage tubes which had been pre-
viously fired, thus clearing the impulse storage section.
Breaking of commutator 3 also opens the trailer card
control tube anode circuit and drops out the TC relay.
Any card which follows a trailer card in the machine
will
be
rejected unless it
is
a master card;
iQ
which
case,
new master card circuits will be set up
as
de-
scribed in the foregoing circuit description.
Single Master Card Operation
When
detail cards are immediately followed
by
a
master card instead of a trailer card, the master card
is
sensed
by
the master rail brush before it reaches the
card brush station. Operation
is
identical to that
de-
scribed under the heading Firing the MCC Tube. The
MC relay
is
picked up; all impulse storage tubes are
de-
energized to clear out previous information; the MCR
point
sets
up a circuit to the selecting commutator and
the contact roll for sorting the master card; and com-
mutator 3 re-applies anode voltage
to
the impulse
storage tubes in preparation for storing information
sensed in the master card. The master card
is
sensed
by
the card brush and sorted to its proper pocket, and
all detail cards following it sort into the same pocket
until the advent of another master card.
Purpose
of
Miscellaneous Circuit Components
The .001 mfd capacitors connected between the con-
trol grid and the cathode of each 2D21 tube serve to
by-pass transient impulses which may otherwise
fire
the tube at
the
wrong time.
The 500K resistor, attached to and in series with
the control grid of each 2D21 tube, limits the grid cur-
rent to the proper value.
The 47K resistor in the cathode circuit of each
2D21 storage tube serves to limit the anode current
through the tube.
The 500K resistor between the cathode of each 2D21
storage tube and its impulse emitter segment
is
actually
connected in series with the
47K
resistor in the cathode
circuit. These resistors are placed
across
the DC machine
circuit together and act
as
a voltage divider when a
hole
is
sensed in the master card, thus developing a
difference
in
potential between the cathode and grid
of the storage tube and causing it to
fire.
The
.05
mfd capacitor in the grid circuit of each
2D21 tube
acts
as
a blocking capacitor which isolates
the
-40
volt
bias
supply from ground (zero volts)
The rectifier in the
OA4G starting anode circuit pre-
vents firing of additional lower value impulse storage
tubes after the
OA4G trigger tube has been fired from
a value sensed
in
the master card. Without the rectifier,
additional impulse storage tubes could
fire
from the
inherent positive potential on the starting anode of the
conducting
OA4G
as
the emitter brushes sweep across
their segments. Firing of excess tubes in this manner
would place a strain on the power supply.
The 500K resistors connected between the
-40
volt
bias
supply and the grid circuits of the 2D21 tubes
serve to improve the voltage regulation of the bias
source
by
preventing the bias source from rising to
cathode potential when a tube
fires.
The 2000 ohm resistors in the cathode circuit of
the MCC tube and the TCC tube serve
to
limit the
anode current through these tubes.
GS-Rl limits the filament current and voltage of
the 2D21 tubes
to
the proper value.
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