Hitachi RAF-25FX8 Service Manual page 80

7. Buzzer Circuit
• When the buzzer sounds, an approx.
3.9kHz square signal is output from
buzzer output pin
computer. After the amplitude of this
signal has been set to 12Vp-p by a
transistor, it is applied to the buzzer.
The piezoelectric element in the buzzer
oscillates to generate the buzzer's sound.
8. Receive Circuit
12V
R215
• The light receiving unit receives an infrared signal from the wireless remote control. The receiver amplifies
and shapes the signal and outputs it.
Microcomputer
30
Buzzer output
Fig.7-1 Buzzer Circuit
of the micro
30
Sound wave
Q212 R216
0V
R219
Metal diaphragm
V
Voo
+
R217
Vout
IRR
-
GND
Fig.8-1
– 98 –
12V
BZ
Q722
0V
Piezoelectric element
Fig.7-2 Buzzer Operation
R611
13
0V
V
WIRELESS
INPUT
Microcomputer