| 摘要 |
PROBLEM TO BE SOLVED: To provide a fan control circuit capable of restraining parts complexity from increasing due to an increase in the number of fans in a fan speed detection circuit. SOLUTION: This fan control circuit comprises an input switching device 15 and an output switching device 18 switching the input/output of the rotational speed detection pulses of the respective fans 3 (1 to n) in time sharing, and input/output switching circuit 20, an oscillating circuit 6 generating reference pulses, a frequency divider 7, a counter (1) 23 counting the rotational speed detection pulses of the fan 3 (n) selected by time sharing switching, a counter (2) 24 counting the reference pulses, a comparison circuit 8 comparing the number of counts from both the counters, and an output holding circuit 19 inputting the comparative results from the output switching device 18 and holding them so that the respective fans meet them, wherein the comparative results which are held in the holding circuit and which the respective fans meet are reported to a control part 2 monitoring a radio transmission pat 1/fan part.
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