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1C15
@ (Vop)
iclS
(INH)
ics.
POWER ON
sv > |
ov.
ve
ov
5yv—
Vv
(To 044)
1c15
ase
collector
1c2
Q36
base
Q36
coliector
7.5V—> | gy__
(voc/a)
Muting voltage
4
sv-——> | Display ON
ov
|
Mute OFF
44v——
|
a aaa ena ae cee) a
eee
|
|
,
POWER OFF
{
{
|
|
|
|
aa (i
en
I
' DTS operation
H
hs
al
Display OFF
Soar
Mute ON
". When rising time
|
1
of VAEF is late
t
'
Mute release
Fig. 2
Auto-Stop Signal Generator Circuit
In FM mode: When no signal input (at no station) (Detune):
Since
the
range
mute
signal
(LA1231N
daughter) is 5V, IC1 @ is -15V. For this, Q19
turns ON and IC1 © becomes 6.5V. At this
time, as the S-meter voltage is less than 1V,
IC1
@
(auto-stop
signal
output)
becomes
-15V.
: When a weak signal is input (receiving broad-
cast) (weak signal area: less then approx. 10
dBuv):
The range mute signal becomes
1V or less
and IC1 @ becomes +15V.
For this, Q19
turns OFF.
However, since the S-meter vol-
tage is low, IC1
Mis -15V.
LA1231N
signal
ee
ov
range
mute
AM+B(+15V)
RSI
47K
RG)
22K
~15V
AM S-meter voltage
Fig. 4
DER}
Ics
176)
R22
2.2m
claz 2.tyso
ok
(276)
In steady state
(VReF)
7.5V
In steady state: 2.5V
Icis.
(6/6)
(376)
: BV
KT-1100D
FL +B (18V) OFF
ac
at H level
(To base of 044)
3-pin regulator, 5V OUT
cl2s
0.0r
Power OFF mute
Muting voltage
(To emitter of Q37)
SV
POWER OFF — ON mute
Fig. 3
: When the broadcast station is received (more
In AM mode:
+15V
tv (6.5V)
RT!
680K
than 10- 14 dByV):
Since the range mute signal is OV, Q19 turns
OFF and IC1 ® becomes 1V. And since the S-
meter voitage is high (IC1 @ > 1V), |IC1 @ be-
comes +15V.
Since AM + B signal is applied to IC1 @, ICI
@ is +15V regardless of the range mute signal
state (H or L). Therefore Q19 turns OFF and
IC1 ® becomes 1V. For this, when the AM S
meter voltage is raised and IC1 © > 1V, stop
signal is generated.
Auto stop signal
014
R68
tooK
FM S-meter voltage
To DTS (AUTO STOP)
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