Width And Delay One-Shots - Wavetek 145 Instruction Manual

waveform with the front panel function switch. This output,
a normal pulse or a complemented pulse, is routed to the
square wave shaper and output, if selected, through the
output amplifier as a variable amplitude pulse. The pulse
modes of normal, delayed and double are shown as timing
diagrams in figures 4-4, 4-5 and 4-6.
4.5 WIDTH AND DELAY ONE-SHOTS
The pulse width and delay one-shots feature front panel
adjustable current sources to regulate the capacitor charge
time and as a result, the one-shot pulse width. The steady
state condition of the one-shot circuit is as shown in figure
4-7: Upon triggering,
0
goes low, the switch transistor
switches off and the capacitor begins to charge. When the
voltage across the capacitor is sufficient, the level detector
senses the set level, the flip-flop is cleared and the circuit
reverts to its steady state condition. The duty cycle of the one-
s hots is limited by the capacitor discharge time when return-
ing to steady state conditions.
HYSTERESIS
~----------------------~
SWITCH
t - - - - 9 1
I+
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I-
TRIGGER
COMP EN-
SAT ION
CR7
*
I+
TRIGGER
@
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SYNC
(Pl-1)
0
®
NOUTPUT
~
I
- -
-
-
-
CR26
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TRIGGER TRIGGER
©
CONTROL SQUARING
LOGIC
©
CIRCUIT
L
TRIGGER/PULSE BOARD
- - - - - - -
TRIGGER
~~LEVEL
:::::;;":
~
~ ___J~, ---------,'----~
'
'
®·®
+
©
+--~
@
+
®
+
--1
0 :
®
+
Figure 4-3. Tri°gger Circuit and Timing
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fRIG
IN
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4-3