| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit breakdown preventive function against a high voltage input with a simple construction in a power supply circuit which is composed of a power supply transformer, a rectifier and a smoothing capacitor. SOLUTION: An AC power supply 1 is converted into a DC power supply by a power supply circuit which is composed of a power supply transformer 2, a rectifier 3 and a smoothing capacitor 4 and supplied to the operation circuit of an apparatus. A normally-closed contact 6 is connected in series to the one end of the primary input of the power supply transformer 2 of the power supply circuit. Further, a voltage detector 8 which detects a smoothed voltage and a drive circuit 9 which releases the contact by the output of the voltage detector 8 which detects an abnormal voltage are provided on the output side of the smoothing capacitor 4. |
