Sorting Circuits - IBM 80 Customer Engineering Manual

26 CARD SORTING MACHINE, TYPE 82
the capacitor, travel through terminal 17, MC-AU,
terminal 8, contact roll cover switch 2, terminal 7,
jumper in place of R5, TD-BU, stop key, pocket stop
contact, motor control relay, MC-AL, terminal 18, 1000
ohm resistor, terminal 22, 10,000 ohm variable re-
sistor, terminal 21, to the positive plate.
This discharge keeps the motor control relay piCked
until the current flow from the capacitor falls below
the value required to hold the relay energized. As long
as the motor control relay remains piCked, me MC-BL
point maintains a circuit through the motor relay, and
the motor relay points, in turn, maintain a circuit to
the drive motor. Prolongation of the circuit to the
drive motor in this manner allows the last card in the
machine to be fed to its proper pocket before the
machine stops.
The 10,000 ohm variable resistor in series with the
runout capacitor should be adjusted so that the drive
motor will keep running for
.5
to 1 second after the
last card drops in the 9 pocket. Decreasing the effective
value of the variable resistor will prolong the runoue
time; increasing the effective value of the variable
resistor will shorten the runout time.
The runout circuit is rendered inoperative in the
event. that the machine is stopped through opening of
the pocket stop contact, raising of the contact roll
cover, or depression of the stop key. Under anyone
of these conditions, the machine will coast to a stop as
soon as its inertia is overcome by friction.
The 47,000 ohm resistor whiCh shunts the terminals
of the runout capacitor serves to bleed off the charge
after the machine has been stopped through operation
of the pocket stop device, raising of the contact roll
cover, or depression of the stop key.
SORTING CIRCUITS
BECAUSE the Type 82 sorter operates at a speed of
650 cards per minute, the sort magnet armature must
be attracted very quickly (.005 seconds or less) so that
the cards will sort properly without being nicked by
the tips of the chute blades. Relay operation, as in the
Type 80 sorter, is not dependable at this speed; there-
fore, an electroniC circuit is used. Not only does the
electroniC circuit provide the necessary speed of opera-
tion, but it also eliminates burning at the contact roll
and the selector commutator because of the small
amount of current used to control the energization of
the sort magnet.
Before proceeding with tJhe study of the sorting
circuits, it may be well to review some of the basiC
principles of electronics as an aid to the better under-
standing of these circuits.
1. In this presentation, current flow shall be estab-
lished synonymous with electron flow and shall be
considered as flowing from negative to positive.
2. When current flows through a resistance, the
voltage is negative on the end of the resistor where
the current enters and positive on the end where the
current leaves.
3. When there
is
no current flowing in a
res~tor
network there will be no voltage drops across any given
resistors in that network.
4. The term "ground" refers to a zero potential
value. Usually the negative power input lead is con-
sidered to be at ground potential. Voltages measured
from this reference may be positive (above ground)
or negative (below ground).
5. Current or electron flow in a vacuum tube or
a gas tube is always from the cathode to the anode
(plate) and can take place only when the anode is
positive in respect to the cathode.
6. The control grid of a vacuum tube is physiCally
located between me cathode and the anode and acts
as a valve in regulating the flow of electrons from the
cathode to the anode. This control is accomplished by
varying the amount of negative voltage applied to the
grid. Increasing the negative voltage on the grid can
slow down or completely cut off electron flow from
cathode to anode, even though the anode (and screen
grid) are positive in respect to the cathode. Decreasing
the negative voltage on the grid can start or speed up
electron flow from cathode to anode as long as the
anode is positive in respect to the cathode.
7. The constant
DC
voltage applied between the
control grid and the cathode of a tube is called the
bias voltage. When such a voltage is applied to the
control grid, it is negative with respect to the cathode
potential and is called grid bias. When such a voltage
is applied .to the cathode, it is positive with respect to
the voltage on the control grid and is called cathode
bias. Regardless of whether grid bias or cathode bias
is used, the purpose of both is to make the control grid
negative with respect to the cathode.
8. The screen grid of a vacuum tube, physiCally
located between the control grid and the anode, may
have a positive voltage applied to it, thus aiding the
anode in attracting electrons away from the cathode.