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CIRCUIT DESCRIPTION
Circuit description
Mutual Reset Operation
1) During operation of this unit, when the external RST signal
becomes low, the DAR (Digital Audio RST) key is turned
ON and IC1 (microcomputer) turns the P-CON output (ac-
tive low)
to OFF
(becomes
high).
Therefore,
P-CON
becomes low.
(However, since the unit is set to the tuner mode, opera-
tion of the tuner is possible.)
DIN 3Pin
z=
P-CON o—_
o_o
P-CON
(ACTIVE
LOW)
OIN 7Pin
KEYMATRIX
(DAR)
RST
07!
(ACTIVE
LOW)
BA3708F Gap Detection IC
1. Outline
The BA3708F is the gap detection IC for the blank sections
between tunes (taped selections). Designed to search for the
beginning of tunes desired for play. This function operates on
3 Volts.
When the level of the signal is higher than the input judgment
level Vin and the signal length is longer than the music signal
Te
Input signal
of f (open)
Mute
on(GND)
"Hy"
Output
4
2) When
the tape is loaded, the microcomputer turns the
P-CON output to ON (becomes low). So, the P-CON is in-
verted to high. Then the external RST signal is inverted to
high so that the DAR key is turned OFF.
3) When
1) occurs during the operation 2), the tape will be
ejected.
detection time Tc, this IC outputs a pulse, with a width of Tw,
after a pulse delay time Td has elapsed from the end of that
signal. The output signal is the open collector signal which
can drive the plunger directly.
It also has a mute function which forcibly stops the detection
operation.
Tc
Plunger ON
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