Hitachi RAC-18SX8 Service Manual page 131

4. Remote control reception circuit
Remote control
reception input
Microcomputer
IC601
[Typical communication waveform]
Remote control reception input
^6
(pin of microcomputer)
Beep (reception tone)
5V
・An infrared signal from the remote control unit is converted to an electrical signal by the remote
control light-receiving unit (IC821) and is received by the microcomputer. Data is transmitted as
digital data 0 and 1 by changing the interval of the basic pulses at about 420μs.
12V
Q821
R821
R640
66
0V
Approx. 400 ms.
Enlarged reception waveform
Approx.
420μs.
Remote control
light-receiving unit
R822
Ⅰ C821
C822
C821
VDD
R823
VOUT
GND
Fig. 4-1
Fig. 4-2
– 164 –