POWER DESIGNS 3K10 Manual page 8

3K10
SECTION 3
THEORY OP OPERiiTION
3-1. GENERAL
The Model 3K10 contains two separate regulating loops; one a
fast regulator of the conventional series pass transistor type; the
other a pre-regulator which operates to hold the voltage across the / '
series pass transistor constant and in its operating range.
The sub-assemblies making up the Model 3K10 are encapsulated
in a series of epoxy modules to minimize corona noise and provide
high voltage isolation as well as environmental protection. Since
the power supply is made up of physically separate modules, the oper
ation of the unit will be described in terms of the function of each
module.
3-2. AUXILIARY POVffiR SUPPLY
This section, consisting of the AS-OIA module, powered by trans
former T1, produces bias voltages for the control circuitry. The
outputs from this section are:
+40 volts (unregulated): Pin 3
+20 volts Pin 4
+15 volts Pin 5
-20 volts Pin 7
-10 volts Pin 8
- 5 volts Pin 9
3-3. FEEDBACK DIVIDER
This is a voltage divider in the fast regulator loop which
senses the regulated output voltage, compares it with a reference
voltage, and feeds an error signal to the regulator.
The high voltage end of this divider is in the PB-01 block.
The resistors in this block are temperature compensated.
The low voltage end of the divider is made up of resistors R21
vernier potentiometer R36. These low temperature
coefficient precision wirewound resistors are switched in and but of
the circuit by means of the front panel voltage selector switches.
Trimmer potentiometer R37 provides a small voltage adjustment for
use in calibrating the power supply.
3-4. ERROR AMPLIFIER
i • •.
This is a two-stage DC amplifier housed in modules EA-01 (first
stage) and AA-01 (second stage). The input to the amplifier is derived
from the feedback divider and an AC feedback capacitor (FB-01 block).
The output feeds the series pass transistor in such a manner as to
maintain the regulated output voltage and degenerate output noise and
ripple.
901 3_1