| 摘要 |
PURPOSE:To prevent a fire and other accidents by detecting a current peak value and outputting an alarm signal, if said peak value is higher than a present given value. CONSTITUTION:In a constant-voltage DC-DC converter, a DC power source E is turned ON and OFF by a transistor TR1 to provide AC power. The AC power is introduced to a transformer T for voltage conversion, rectified and smoothed by a diode 8 and a capacitor C3, and supplied to a load 10. Further, the voltage across the load 10 is detected by a potentiometer 7 and an ON-time length of the TR1 is controlled by a controller 11 so that said voltage is held constant. In this case, a current-limiting resistor R1 is connected in parallel with a peak-detecting circuit consisting of a diode 9, a capacitor C2 and a potentiometer 6, and the peak value detected is inputted to comparators 2-1, 2-2 having reference voltages 4, 5 to produce control outputs for Tr2 and the controller 11. Thus, deterioration of an electrolytic capacitor C1 can be detected.
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