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THEORY OF OPERATION
The PS-28D Assembly is an- unregulated power supply that pro
vides the basic +8, +16, and -16 voltages for the 8080 sys
tem.
It is comprised of four major component assemblies:
line filter, transformer, rectifiers, and filters.
The line filter is a triple PI L-C filter designed to remove
high frequency noise present on the AC line.
attenuates line noise above 1 MHz in frequency.
The transformer primary is designed for a nominal 117 volt
line, and 0, -10%, and +10% taps allow for adjustment to
line voltage variations.
nected as three series winding with a center tap.
MR 1121 diodes full-wave rectify the +8 volts, while a full-
wave bridge of four MR601 diodes rectify the ±16 volts.
The +16 volt supplies are each filtered by a 10K uF capacitor
to ground, providing +15 average volts at 4.0 amps.
+8 volts is filtered by two 95K uF capacitors to ground, pro
viding 7.3 average volts at the 28 amp rated current.
.luF capacitors bypass each voltage supply, and bleeder
resistors discharge the filter capacitors when power is
turned off.
3 - 2
PS-28D
Theory of Operation
The transformer secondary is con
This filter
Four
The
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