F. R E F E R E N C E C IR C U I T
r:- - - - - - - - -
1
R e f e r e n c e
l
I
b r i dg e
I
R t 4
R
1 6
R l 7
L
_ _ _ _ _ _ _
_J
r:- - - - - - - - - ,
I
R e fe r e n c e
I
b r i d g e
I a m p l i f i e r
T t o
I
L
N e g at iv e s u p p l y
_J
- -
-
- - - - -
csi
U nr eg.
2 5 V
S t a bi l i z e r
f o r r ef e r e n c e a n d i n t e r n a l
s u p p l y v o l t a g e s
F i g u r e
2 6
Z
1 is a temperature compensated zener diode,
·
which supplies a highly
stable reference voltage for RACPAC .
The "Reference bridge" is stabilized by the "Reference bridge amplifier" .
This serves two purposes :
1. To supply a stable current to the reference zener diode
Zl.
2. To supply a stable voltage (+12V) to other amplifiers.
The "Reference bridge amplifier" consists of a temperature compensated
input stage T3+D7, a driver stage T9 and an output stage TlO.
The zener diode
Z3
+ transistor T12 are inserted in the reference supply
in order to achieve a negative
(-6V)
power supply to other amplifiers.
T12 increases the current handling capability of
Z3.
30
