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At 100 VAC, 50 Hz, resistive load:
25.0 amperes at
4.0 amperes at +13.5 volts ripple valley
4.0 amperes at -13.5 volts ripple valley
THEORY OF OPERATION-
The PS-28U is an unregulated power supply that
provides the basic +8, +16, and -16 voltages for
the 8080 system. It is comprised of four major
component assemblies: line filter, transformer,
rectifiers, and filters.
Line Filter:
The line filter is a triple PI L-C
filter designed to remove high frequency noise
present on the AC line. This filter attenuates .
line noise above 1MHz in frequency.
Transformer:
The transformer is primarily designed
for a number of AC input voltages: 92, 103.5, 115,
126.5, 184, 207, 230, and 253 VAC, 50/60 Hz,
single phase input. The transformer secondary is
connected as three series windings with a center
tap. Four M R 1121 diodes full-wave rectify the
+8 volts, while a full-wave bridge of four MR 501
diodes rectify the + 1 6 volts.
Filtering:
The +16 volt supplies are each filtered
by a 10K uF capacitor to ground, providing +15
average volts at 4.0 amps. The +8 volts is filtered
by two 95K uF capacitors to ground, providing
7.3 average volts at the 28 amp rated current.
.1 uF capacitors high frequency bypass each voltage
supply and bleeder resistors discharge the filter
capacitors when power is turned off.
POWER SUPPLY PS-28U
Theory of Operation
Revision 1
+7.0 volts ripple valley
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