– 102 –
7. Buzzer Circuit
• When the buzzer sounds, an approx.
3.9kHz square signal is output from
buzzer output pin of the micro
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.
30
0V
Q722
R219
12V
Fig.7-1 Buzzer Circuit
Fig.8-1
Fig.7-2 Buzzer Operation
Metal diaphragm
Piezoelectric element
V
Sound wave
Microcomputer
Buzzer output
BZ
30
V
8. Receive Circuit
• The light receiving unit receives an infrared signal from the wireless remote control. The receiver amplifies
and shapes the signal and outputs it.
WIRELESS
INPUT
Microcomputer
R611
R217
IRR
0V
0V
12V
+
-
Vout
Voo
GND
C611
C211
ZD211
C213
C212
13
Q212
R215
R216
