TM 1 I-6625-2965-14&P

SECTION IV

PRINCIPLES OF OPERATION

REFERENCE

REGULATOR

CIRCUIT

t

 

 

 

AC

POWER

 

B I A S

I N P u T

TRANSFORMER

SUPPLY

 

 

 

 

I

~o RECTIFIER AND

F I L T E R

Pm

RANGE

SWITCH ( s 2 )

NOTE

—D E N O T E S V O L T A G E FEEOBACK PATH

—D E N O T E S C U R R E N T LIMIT PATH

B IA S

v VOLTAGES

SERIES

REGULATOR

A

DRIVER

 

 

 

 

4

 

 

 

 

 

 

 

 

CURRENT

 

 

 

 

 

 

 

 

LIMITING

 

 

 

 

 

 

 

 

 

 

C I R C U I T

*

 

 

 

 

 

 

 

 

 

 

 

 

 

P/o

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

CURRENT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

s A M P L I N G

 

 

 

 

 

 

 

 

 

 

RESISTORS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CONSTANT

4

 

4

 

 

 

 

 

 

 

 

 

 

 

 

 

VOLTAGE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INPUT

4

 

 

 

 

 

 

 

 

C I R C U I T

 

 

 

AMPL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

+

 

 

 

 

 

 

 

 

 

C I R C U I T

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1, Q

Figure 4-1. Overall Block Diagram

4-1 OVERALL DESCRIPTION

obtain the proper regulated dc output voltage.

4-2 Figure 4-1 shows one section of the Model 6205B dual power supply. The supply consistsof two dual range sections; each identical to the other. Each section consists ofa rectifier and fil- ter, a series regulator, an error amplifier and driver, a constant voltage input circuit, a cument limiting circuit, a reference regulator circuit, a bias supply, and a metering circuit. Since both sections of the supply are identical, only one section is described below.

4-3 The ac line voltage is first applied to the power transformer, The tap for the appropriate voltage range is selected by S2. The input is then rectified and filtered. This raw dc is then fed to the series regulator which alters its conduction to

4-4 Any changes in output voltage are felt by the constant voltage comparator which compares a portion of the output with a fixed reference volts ge. If a difference exists, the comparator circuit sends a n error signal to the series regulator via the error amplifier and driver stages. This error signal changes the conduction of the series regulator so that a constant output voltage is maintained.

4-5 Changes in output current are reflected in the voltage drop across the current sampling resistor network. If this voltage drop exceeds a preset limit, the current limit transistor conducts, sending

aturn-down signal to the series regulator via the driver. This signal changes the conduction of the

4-1