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KX-F910BX
13-7. CIRCUIT OPERATION OF PORTABLE HANDSET
(1) RF Transmission/Reception Power Supply Circuit
The power source for transmission is switched on and off by the CPU that controls Q14, Q16 and Q17 for
battery current. It is stabilized the constant voltage by the 3 V regulator and supplied to the RF unit and IF
IC. In the standby mode, Q16 is switched ON and 3 V is supplied to the RXB via IC3 only when pin
becomes Low. In the TALK mode, when pins
approx. 3 V is supplied to the RXB via IC3 and TXB via IC8. And then, pin
approx. 3 V is supplied to the TXPB .
(2) Electric Field Detection Circuit
The electric field detection circuit that consists of the DET Amp., IC1's noise filter, integration circuit and
comparator detects the electric filed by checking noise.
The audio signal output from pin
amplified by the DET amplifier. After the noise is converted to the De voltage in the integration circuit, it is input to
the comparator to gain High and Low outputs.
Pin
decides the sensitivity of the integration circuit and pin
49
In the strong electric field, the De voltage of pin
In the weak electric field, the De voltage of pin
Integration circuit
DET Amp.
C20
R116
CN1
1
Audio
C74
VR1
C202
C64
and
23
Q16
+
–
Q14
22
23
CPU
CPU
RX POWER
TX POWER
of CN1 extracts noise of approx. 18 kHz by the noise filter of IC1 after it is
1
52
52
Circuit Diagram
(IC1)
Noise
Filter
C18
R118
54
C63
C19
–
55
R13
+
R1
Q15
1.9V
R117
are set to Low and Q16 and Q17 is switched ON,
31
IC3
Reg.
3.0V
Q17
31
CPU
TX PLL
decieds the time constant.
52
is 0.5 V or less, pin
outputs Low.
48
is approx. 1 V, pin
outputs HIGH.
48
Integration Circuit
49
52
R11
C16
R9
|180 |
is set to Low, Q14 is ON and
23
RXB
TXPB
IC8
Reg.
TXB
3.0V
Comparator
R8
48
22
CPU
19 pin
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