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PHASE LOCKED LOOP CIRCUIT
This circuit accurately creates a switching signal which
divides the stereo components of the
divided
into
two parts: an oscillator and a section
COMPOS IT
SIGNAL( INPUT)
0,047 l5K
I
y4
I
I
I
L------- ,
A
1
Operation
1. Oscillator Section
a. A
76kHz sine wave is
formed by Tr6 and Tr7. It is changed into a square
wave at Tr8 and then fed to the doubled multi
vibrator formed by Tr9 and Tr10. Thus at OR and
OL
38kHz
square
waves of opposite
obtained.
At the same time this 38kHz signal is fed to the
lllni1Jl
CHART'
0
1
2
3
4
5
(I)
76KHz
POINT@
Notes:
1. Waveforms at point(@ are the same square wave
as at pointeD, but phasing is opposite.
FM
signal. It is
0
STEREO INDICATOR
obtained
from the VCO
phase
are
LilSl
(2)
POINTQ)
CHART 2
6
7
8
0
1
CHART 3
, , , ..... ,
to match the oscillator 19kHz pilot signal to the broad
cast pilot signal.
ORR CHANNEL
CIRCUIT
doubled multivibrator formed by
creating 19kHz square waves of opposed phase at
CD
®.
points
and
Waveforms and phase relations at
each time point are as shown below:
b. As a principle of operation, the oscillation frequency
(phase)
of the
VCO rises (advances)
potential becomes more positive, and drops (retards)
as it becomes more negative.
CHART<
2
3
4
5
6
7
8
CHAR"
CHARTS
L
CHART2
2. The waveform at point(i)is the same sq urr
as that at point
OL L CHANNEL
Fig.
Tr11 and Tr12,
as the
(3)
POINT®
2
3
4
5
6
_fL
7
0
I
2
3
4
5
6
' ,
. ,
,
.
.
.
,
L_j
0
2
3
4
5
Fig.
E
Ckl,
but the phase is opposite.
CT-7000
6
Tr6
7
8
8
7
8
7
w ave
9
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