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E L E C T R I C A L
P R I N C I P L E S
5 1
Any timed impulse from 9 through 12 is available
at the distributor hubs labelled accordingly.
The
distributor can also be used as a digit selector by
wiring from the brushes to the C hub of the dis-
tributor.
Only the desired digit in any card col-
umn can be recognized by proper wiring of the
9-12 hubs of the distributor.
POWER SUPPLY CIRCUITS
Main Transformer and Selenium Rectifiers
Power is su2~lied to this machine by two trans-
formers, the main transformer and the tube power
supply xransformer, which can be seen in the
power supply circuit diagram (Section 3 for 11 5
-
2 3 0 volt A.C. operaxion and Section 4 for 1 1 5 volt
A.C. operation). The main transformer is mounted
directly behind the control panel. The only dif-
ference between the 11 5 volt A.C. xransformer
and the 11 5-230 volt A.C. transformer is that the
latter has two primary coils.
All following dis-
cussion will assume a 11 5 volt A.C. transformer.
Three taps are provided in xhe primary to permit
constant secondary output voltages at 105, 11 5,
or 12 5 volt primary voltages.
The secondary is
provided with six taps to supply 115 volts A.C.
for the tube filamenxs and to supply the selenium
rectifiers which provide D.C. outputs of 40 volts
and 140 volts. The 140 volt supply is the anode
voltage supply for the 25L6 read-out power tubes
in the electronic compu~ing unit.
The 40 volt
supply furnishes the power for all relays and mag-
nets in the punch unit which are usually supplied
by a generator.
From the punch running circuits it will be re-
membered that when the main line switch is
ON,
the A.C. from xhe main line appears across posts
9 and 10 to pick up HD3 and HD4. The HD4
points in turn complete a circuit to the main trans-
former primary across the two 20 amp fusetrons.
The circuit through the primary of xhe main line
transformer is from post 8, through 20 amp fuse-
tron 3, HD4 points, primary terminal 17, primary
coil, terminal 19 (for 11 5 volt supply), fusetron
4, to post 7. The RMS or effective volxage pro-
duced at
fz~ll load
by transformer action between
each of the secondary taps is shown in Figure 53.
(RMS is the abbreviation for the root mean square
value of alternating current or voltage, also called
"effective value." I t is the square root of the mean
values of xhe squares of the instantaneous values
taken over a complete cycle.)
All tube filaments
in the electronic computing unit are heated by the
11 5 volt A.C. between terminals 13 and 14. The
filamenx supply uses cable connectors CNp18
through CNp20 and CNp38 through CNp40.
Three connectors are used on each side to distribute
the load. I t is advisable to adjust the primary tap
so that xhe filament supply is approximately 110-
11 5 volts. Although the tubes will require slightly
longer to heat, their life will be considerably
longer.
A 1 5
%
increase in voltage will reduce
the life of the tubes 30%.
40 volt D.C. is supplied by the full-wave selen-
1 s rec-
ium rectifier across terminals I I and 12. Th'
tifier is mounted on the right end gate. The cenxer
connection of the selenium rectifier is the positive
connection while xhe transformer center tap be-
tween terminals 11 and 12 (terminal 15) is the
negative connection.
Terminal 15 serves as the
reference point for
all
voltages, i.e., it is the point
of zero reference and is the ground connection.
Four 2000 mfd, 40 v o l ~ electrolytic capacitors con-
nected in parallel act as the filter for the 40 volt
supply.
These capacitors are mounted on the
lower section of the left end gate. Post 1 and post
3, which are the 40 volt terminals, are connected
across the 2000 mfd capacitors.
The actual D.C. voltage produced at the output
terminals is greater than the A.C. voltage at the
xransformer secondary
because the capacitors
charge to peak voltages. The actual D.C. voltage
is equal to the peak voltage of the A.C. ( 4 2 times
the RMS voltage) minus the voltage drop across
the selenium rectifier stack, which is approximately
6-10 volts at full load.
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