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0653
15.625 Hz
HD out to
HD amp
camera
Q651, Q652
1C651
317.25 kHz
t/2 & f/625
X.tal OSC
count down
head drum
mu— 13.125 kHz FG putput
pulley
Q601, Q602
D601, D603
13.125 kHz
amp.
50 Hz
Q706
VD out to
| |
|
Q654
10607 (1/3)
:
Q711
25 PG
25 PG coil
amp
PG pole piece
video head assembly
Q603, Q604
1€601(1/3)
1C601 (1/3)
Q605, Q606
Q607
Schmidt
trigger
Q708
R625, C620
0608, Q609
integrator
Fig. 8-2.
Camera record mode, block diagram
limiter output
Schmidt trigger
output
FG amplifier
(Q601, Q602)
flip-flop output
AND
circuit output
Schmidt
trigger
1C601(1/3)
Fig. 8-3.
Servo waveforms
head.
The
head
rotates
at
25 rps. so
that
the
frequency
generator
coil
produces
a
13.125 Hz
output.
Faster
rotation increases FG frequency
output
and slower
rotation de-
creases frequency
output.
The
13.125Hz
FG
output
is
amplified
and
then
amplitude-
limited so that it can drive the
following
Schmidt
trigger
cir-
cuit.
1C601(1/3)
comprises
a
Schmidt
trigger
circuit
that
converts
FG
output
to rectan-
gular pulses.
8-3
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