Pulse Amplifier - Tektronix 7B51 Instruction Manual

Circuit Description-Type 7851
+15V
R234
CR256
0,......1--_ _
LEVEL
R221
-15V
+15V
CR255
+15V
LEVEL/SLOPE
Control
o/jC/J!--
Negative Slope
+50 V
Fig. 3·5. Trigger Path for Negative Slope Triggering (simplified).
input trigger signal and the display is triggered on the
negative-going edge of the input trigger signal.
Trigger TD Stage. The Trigger TD Stage shapes the out-
put of the slope comparator to provide a trigger pulse with
a fast leading edge. Tunnel diode CR262 is quiescently
biased so that it is in its low-voltage state. The current from
one of the transistors in the slope comparator stage is
routed through the trigger TD stage by the SLOPE switch.
The series-parallel combination of L267-R267-C267 with
0266 provide a resistive load for CR262 and form a
3-6
Schmitt circuit. As this current increases due to an appro-
priate change in the trigger input signal, tunnel diode
CR262 switches to its high-voltage state. CR262 reverts to
its low-voltage state when the current from the slope com-
parator decreases sufficiently.
Pulse Amplifier. The trigger pulse from the trigger TD
stage is connected to the base of the pulse amplifier, 0266.
The trigger pulse at this point is basically a negative-going
pulse with a fast rise. The width of the pulse is determined
by the waveshape of the input trigger signal and the setting
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