Conditioning Circuits; Sort Only; Count Only - IBM 80 Customer Engineering Manual

IBM 978 CARD COUNTING UNIT
79
Secondary Voltage
Regulaled a16.3V
Increase of secondary voltage
compensatod for rise in primary voltage
--
Operating Range
10SV AC 126V AC
. Primary Voltage Input 115V ~
Figure 60. Schematic
of
Filament Transformer Output
corresponding reduction in the compensating winding
voltage. This produces a 6.3v output because less
compensating voltage opposes the secondary winding
voltage.
POWER TRANSFORMER (FIGURE
57)
The power transformer provides the voltage for the
DC
supplies. One secondary winding provides 96 volts
AC
for the +60v
DC
supply. The other winding pro-
vides 78 volts
AC
for the +48v and -48v
DC
supplies.
The 96
(RMS)
winding is center tapped to provide
full wave rectification producing +60 volts
DC
across
R1 and Cl. The +60v supply provides the plate volt-
age for the 2D21 tubes.
The 78v
(RMS)
winding is center tapped to provide
full wave rectification for both the +48v
DC
supply
across R2 and C2, and the -48v
DC
supply across R3
and C3. The +48v section is used to supply the relay
circuits for counting functions. The -48v supply pro-
vides the bias voltage for the twelve 2D21 tubes.
Assuming that post 18 is negative and post 16 is
positive at an instant of time, the circuit for the +48v
supply is: post 17, T35, C2, R2, T37, rectifier, post 16.
C2 charges and filters the rectified
AC
voltage across
R2
to
+48 volts
DC.
With the polarity reversed, the
circuit is through the other half of the transformer
winding: post 17, T35, C2, R2, T37, rectifier, post 18.
With the same polarity (post 18 negative) the cir-
cuit for -48v
DC
supply is: post 18, rectifier, T36,
C3, R3, T35, post 17. Electron flow is through R3 to
the center tap of the secondary winding, which is at
zero-volt potential. Across R3, the rectified voltage is
filtered by C3
to
-48 volts
DC.
T35 is at zero volts
and T36 is 48 volts more negative than T35, or
-48 volts.
Conditioning Circuits
To count cards, the count switch must be in the
on position. This provides a circuit to pick R51 (Fig-
ures 61 and 62). The points of R51 electrically con-
nect the counting unit into the circuits of the 82. The
R5 1 BU points transfer and allow the pick of R 113
and R118. A circuit to the time delay relay R52 is
also established allowing the pick of this relay when
the bi-metallic contacts make. Picking R52 completes
the circuit necessary to interlock the 978 with the 82
Sorter. It is now possible to start the 82 Sorter by
depressing the start key. The counter switch also picks
R54 which isolates the counter network while the
machine is idle.
Sort Only (Figure 63)
The principles of sorting are in no way altered when
the 978 card counting unit is installed on the 82
Sorter. Three distinct operations are possible; sort only,
count only, and simultaneous sorting and counting.
When the machine is conditioned for a sort only opera-
tion, the circuit remains the same as the normal 82 sort
circuit with the exception of added normally-closed
relay points.
OBJECTIVE: A sort-only operation. The count switch is in the
OFF position.
1. A plus potential is applied to the main anode of the thyra-
tron tube through the following circuit: + 150v, R1l3-5N/C,
commutator outer brush, commutator center brush, R113-
4N/C, octal plug pin 4, OA4G pin 5.
2. A hole in the card establishes circuit from +150v through
RI13-5N/C, commutator outer brush, commutator inner
brush, RI13-3N/C, common brush, contact roll, card brush,
R1l3-2N/C, octal plug pin 5, OA4G pin
7
(starting anode)
to cause the OA4G
to
fire and go into conduction.
Count Only (Figures 63, 64, and 65)
OBJECTIVE: A count-only operation. The count-only switch
(Figure 63) is in the ON position. The count switch (Figure 61)
is also in the ON position, conditioning the counting circuits and
transferring the normally-closed relay points in the sort circuit.
1. Reading a hole in the card establishes a circuit from the
+150v line, through CI, RI13-3N/O, common brush, con-
tact roll, card brush, RI13-1N/O
to
the number 2 grids of
all the counter tubes.
2. The emitter (same timing as inner segments of commutator)
conditions grid 1 of tubes 9 through 12 in succession.
3. The counter tube corresponding to the hole read in the
card conducts because both grids have been conditioned
positive.
4. Firing a tube permits the pick of a digit memory relay.
5. The counter magnet (Figure 65) is energized by C13
through a network of digit memory relay points.
6. The fact that the count-only switch is in the ON position
prevents a circuit to the commutator inner brush to prevent
sorting.