Wavetek 188 - Page 19

When the
CONT switch is releasee.
trigger logic is in-
hibited from passing
any trigger signals and
the tug-
ger (lip-flop
output
is held
high This prevents
me trig-
ger diodes from conducting and
the generator loop
operates
continuously.
When the CONT switch
is pressed, the generator
looo
is
held at the
OV
baseline.
Pressing the TfliG/GATE
switch
puts the instrument in
triggered mode and any
external or manual
trigger signals
al
the
trigger logic
input will
be
transformed
into
a
narrow pulse
cor-
responding
to
the low-to-high
transition o
I
the trigger
input.
This pulse
sots
the trigger
flip-flop high and
allows Ihe generator
loop
to run
When
the tr.angle
negative
peak is reached, the comparator
low-to-high
transition clocks the trigger
Hip-Hop low and. when
the
OV baseline level is reached,
the generator loop
again
stops The result
is a single cycle generated
after
the triggering
signal corresponding
to
0
to 360* of
phase Successive triggered
waveforms
always start
at Ihe samo
0
*
point.
Roloasmg
the TRIG/GATE switch
puts
the
instrument
In the gated modo This
is identical
to tho
triggered
mode,
except tho trigger flip-flop
is held high for the
full
duration of the triggering signal
Tho generator
produces
continuous waveforms during
the time the
external
signal Is high
or
the manual
lugger swilch is
held
tn The last triggered
cycle started is always com-
pleted
and successive gated bursts
always start at the
0
#
point
When sweep mode is selected
by
a
combination
of
the mam
generator in continuous mode
and the ramp
generator
switches set to SWP. the ramp
generator is
enabled and
a
ramp voltage
becomes part
of the con-
trol voltage
m me VCG circuit to control
me main
generator frequency. Ramp
period, variable from
30 ms to 1 mmute. is
set by me TIME Control. Ramp
generator
output is buffered
to
drive the
sweep output
and
VCG
circuit. The ramp
magnitude suppling
the
VCG input is controlled
by
the
STOP potentiometer.
Selecting the
stop switch position
biases the buffer
amplifier
to a
level
equal to the positive
peak of the
ramp
( + V) In this static mode
the upper sweep limit
can be set
by
me STOP Control
When the
CONT position of the
SWEEP switch is
selected the ramp generator
is disabled and the
buf-
fered
ramp is disconnected
from ihe
VCG
input
The
GCV
(Generator
Control Voitago) from
the
VCG
ci'Cu't IS
a
resultant voltage
from me throe
VCG in-
puts:
dai.
VCG IN and
sweep
ramp
This voltage
is
buffered
and made available
at
the
GCV BNC
4-2