Buzzer Circuit; Receive Circuit - Hitachi RAF-50FX8 Service Manual

7. Buzzer Circuit

• When the buzzer sounds, an approx.
3.9kHz square signal is output from
buzzer output pin
30
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
Sound wave
Q212 R216
+
-
0V
12V
R219
BZ
0V
Metal diaphragm
V
Fig.7-2 Buzzer Operation
Voo
R217
Vout
IRR
GND
Fig.8-1
– 102 –
Q722
Piezoelectric element
V
R611
WIRELESS
13
INPUT
Microcomputer
0V