Tektronix 3A74 Instruction Manual page 23

Circuit Description — Type 3A74
tNPUT INPUT DIODE OUTPUT AMPLIFIER
-- CE i —ameLiFieR —|
switches — "|*—
IST STAGE
+18.5V
wet eneer ey
=3.3ma
BUSSES CONNECTING R444
SWITCHED AMPLIFIERS <
TO OUTPUT AMPLIFIER SIGNAL OUT
Xr .——_ To peiver
EF
D440 Q444
R424 22.5 _
WAY ma 12,.8V Dh
4 Q424 ~12.4V
el.3ma
=3.8 $ 7.1ma
+300V mai §
OFF hf D441 Ne '\
EFFECTIVELY
GAIN +125V 12.4% EACH
=3.8ma
> 4
R438 ~3.8ma l |
D443
Dis
~12.8V =3.BM4
§ R434 22.5 ma
MAA
Q 454
SIGNAL OUT
To DRIVER
EF
R454
LOCATED IN
RING COUNTER |
+ aE SouaPLEMENTARY
+18.5V CURRENT
NOTE:
THICKNESS OF THE HEAVY BLACK LINES
1S SOMEWHAT PROPORTIONAL TO THE
CURRENT FLOWING IN THAT LINE.
NO SIGNAL 1S APPLIED TO THE CHANNEL.
Fig. 4-2. Simplified circuit diagram showing the dc current paths when channel 1 is turned OFF.