Hitachi RAS-25CNH1 - Receive Circuit Function; Buzzer Circuit Function

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2. 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.
3. Buzzer Circuit
18
C702
0V
0V
0V
0V
12V
R710
ZD701
R709
R705
C701
LIGHT
RECEIVING
UNIT
+
–
Wireless input
Micro computer
● When the buzzer sounds, an approx.
3.9kHz square signal is output from
buzzer output pin q 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.
Fig. 3-1 Buzzer Circuit
Sound wave
Metal diaphragm
V
Pizoelectric element
V
Fig. 3-2 Buzzer Operation
Micro computer
Buzzer output
BZ1
12V
R801
Q805
21
BZ
0V
Fig. 2-1