TS-440S
CI RCUIT DESCR IPTION
2) AF
notch circuit
123------ 10
BX7191
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-- -- - ---- -- -- ---- ----------,
I
I
R2 38K
R6 IOK
2
G
AF
INPUT
C60
I IN
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il
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L_
__
OUTI
9
0 +
"'
u
CD
CD
027
"'
Riii 27K
RS
22K
R7
IOK R9
22K
..
u
026
ev
RIO IOOK
VR2
8
VR3
7
6
C65 .0039
.-
-,
X41-1610-00CA/4l
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Fig . 5 NOTCH circuit
The hybrid IC 1 in the IF u nit is a n au dio notch circuit .
Fig ure 5 shows its equivalent circuit . This circuit forms state
varia ble band pass filter, also known as a bi-quad filter . The
notch frequen cy can be cha nged using the notch control vari
a ble resistor . Since the circuit consists of the hybrid IC, sta
ble attenuation characteristics can be obtained electrically and
thermally. The range of variable notch frequencies is 400 Hz
to 2600 Hz .
The notch frequency is determined by the following two
formula s .
1 )
+ Notch VR)·R 8·R 1 0·C 1 ·C65 .. . . . . . . . . 1
2) R6·(R 1 2 + R 1 3)�R 1 0·R 1 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
If a variable resistor is used for resistor N OTCH VR, the notch
frequency can be controlled according to formula 1 ) .
The notch frequency range i s from 4 0 0 to 2600 Hz, and at
ten u ation is from 25 to 50 d B.
9