| 摘要 |
PROBLEM TO BE SOLVED: To identify an output-on and an output-off under normal conditions from those under anomalous conditions and display it. SOLUTION: This failure detection circuit for switching power source consists of a switching power source circuit SW1 conducting power feeding operation by working, if the output voltage of a rectifying and smoothing circuit 3 connected with an AC power source 1 exceeds a prescribed value, and a power source circuit SW2 from the AC power source connected with the switching power source circuit SW1 in parallel. If a blocking element F1 cuts off a power feeder line when a circuit is abnormal, a displaying means LED fed by the output of the switching power source circuit SW1 is displayed intermittently by repeating charging and discharging of the rectifying and smoothing circuit 3, according to the time constant of a current-limiting element 4 connected with the blocking element F1 in parallel.
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