Dc Voltage Regulator

TM 11-6130-385-34

2-5. Dc Voltage Regulator

b. A 400-Hz sine wave feedback signal from the

output filter is directed to the output voltage con-

a. The dc voltage regulator board provides 8-volt,

trol. The feedback signal is also connected to a turn

2.5- and 5-volt regulators and a negative 3.4-signal

on sense output (at terminal 20) which is coupled to

for negative bias. A high and low input voltage

the overcurrent sense and foldback circuit on the A

detector circuit senses high and low input voltages

p h a s e modulator board.

a n d disables the system output when required.

c. The output voltage control circuit (fig. 3-18)

b. The dc regulator board also receives data from

r e c e i v e s the feedback signal, Potentiometer R356

t h e modulator boards which is augmented in the

and the temperature compensator unit U310 develop

output drive circuit and conducted to the power

t h e signal. The signal is then delivered, with dc

switch boards. Data from the dc regulator board is

i n p u t , to comparator U306. Transistor Q304 func-

received on the base drive circuits of the power

tions as an integrating amplifier with dc output and

switch

boards.

is applied to field effect transistor Q306 gate which

2-6. Power Switch Function

c o n t r o l s amplitude of the sine wave input to the

On the three power switch boards, transistor power

m o d u l a t o r and square wave generator circuit. FET

switches conduct the signal through an inductor to

Q306 functions as a voltage impedance device. Gate

t h e power transformer and then out to the filter.

v o l t a g e impedance is as follows:

There are boards for A phase, B phase, and C phase.

Impedance

Gate voltage

2-7. Modulator Circuit Description

+2.5v . . . . . . . . . . ..100 ohms

3.4v . . . . . . . . . ..2 megohms

a. The modulator circuit functions as follows: The

high frequency 6.4-kHz square wave signal from

d. The square wave generator and modulator (fig.

oscillator board A 1 enters B phase modulator board

3-25) compare ramp signal with sine wave and

A3 as two square waves 180° out of phase (fig. 3-23),

m o d u l a t o r output pulse length in accordance with

T h e y are capacitor-coupled to differentiate for the

relative amplitude of these signals. The outputs go

summing diode circuit CR305, CR306. The resultant

to the data generator. The data generator (fig. 3-20)

12 .8-kHz signal is introduced to the ramp generator

correlates the information for transmittal to the

( U 3 0 5 ) and initiates the output data (ramp) to the

o u t p u t drive board. Transistors Q309, Q310 disable

output drive board. Ramp generator U305 also

o u t p u t data during reset of ramp generator.

delivers a ramp reset blanking signal to Q309, Q310.

2-2