– 51 –
4. Initial setting (IC401)
The pre-heating operation start value, ratings of the compressor, maximum rotation speed, etc. are preset in
the micro computer.
87
IC401
(E
2
PROM)
65
5V
Micro computer
(AX-3U)
58
59
C401
R404
R403
12 4
0V
3
3. Buzzer Circuit
Fig. 3-1 Buzzer Circuit
Sound wave
Metal diaphragm
V
Pizoelectric element
V
Fig. 3-2 Buzzer Operation
Micro computer
(AX-3U)
Buzzer output
BZ1
12V
0V
R801
Q302
21
B.Z
● 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.
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