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2. Buzzer Circuit
Fig. 2-1 Buzzer Circuit
Sound wave
Metal diaphragm
V
Pizoelectric element
V
Fig. 2-2 Buzzer Operation
Microcomputer
Buzzer output
BZ
12V
0V
R722
Q722
30
BZ
● When the buzzer sounds, an approx.
3.9kHz square signal is output from buzzer
output pin of the microcomputer. 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.
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