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E3
0.35 Vpp
E4
4 Vpp
3.15 HORIZONTAL F/V CIRCUIT
(Refer
to
circuit diagram Fig-15)
The horizontal F
IV
circuit is consists of 0400a,
0400b,
0400c,
0400d
and
some
discrete
components. The F
IV
signal is fed to pin 3 of buffer
stage (0400a) via pin 6 of P401, then the output
voltage is applied to comparator 0400b, 0400c· and
0400d.
According to the different input frequency, the output
voltage of 0400b, 0400c and 0400d is fed to pin 8 of
0403 via analog switch 0401 a, 0401 b or 0401 c.
•
1
: ' '(" ..... "':'. ··"(···· ..
·r· .. ···:
':t.· • . [-r.:r.·;·JTT:
l·1
For example:
When input frequency is between 28KHz to 40.8KHz,
Pin 3 and Pin 4 of analog switch (0401 c) is on.
When input is 40.8KHz to 53.6KHz, 0401b is on.
When input is 53.61 KHz to 66KHz, 0401 a is on.
,
,
.. ",'
'!"+ .. -.. ; . . . . . . .
-f-.. -...
'~
.. j,.
! .... : ........ : .......
J ........
L ..
~.~
.........
i
R422, R413 and R420 enable the free-run frequency to
HORIZONTAL FjV CIRCUIT
C451
103J fl496
50Y
ISOK
-l
FROM
I/O...
\40.
S~
• 53. 6Kt:Z JMOIJF.2
{
\2BI< • 40.9r.HZJMOOEI
~I
CRO
til ...
---'-'.:::.:...::"---=:.;;:..:.::::.::.===-------,~----.
B,)ARO
H2 .... _ _ ....:(-'-53"" • ..o:.6.;..:.IK_ • ...;;6""6K""H""Z' " ' J M,.:-00""F.:..:;..3 _ _ _ _ _
--'->
R495
1001<
I~
0451
IN4148
R400
lOOK
!%
R401
180K
!"
R422
9
5KB
R423
!l499
581(
@
C452
0.L2U
1 -
50,
CD® @@®®®
.311(
0.5
0.6
O.G
o.~
12
0
0
48K
0.';
6.3
14.? 5.9
0
12
0
641< 12.
14.
J4.711.2
0
0
12
12'J
R415
360K
I~
R416~~~6
6.2K
I~
R417
I.
21<
I~
=
3-13
=
ti.HOLD3
121<
10
0'101
c
Q403
-9
10 H.ose
C!RCUIT
Fig-15
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