| 摘要 |
PURPOSE:To reduce abnormal voltage (ripple voltage), by controlling voltage to lower output voltage, when the capacity of the electrolytic capacitor of a smoothing circuit is extremely reduced and capacity parting is generated. CONSTITUTION:A switching regulator is composed of an input voltage source 1, a controlling circuit 2 for controlling a transistor(Tr) 4 as a switching element and its pulse width, an insulating transformer 3, a rectifier diode 5, and a smoothing circuit with smoothing capacitors 6, 8 and a choke coil 7. In this case, both the ends of the choke coil 7 set in said smoothing circuit are provided with a loop circuit consisting of a resistor 15, a light emitting diode 12 of a photo-coupler 10, and a diode 16 which are connected in series. As a result, by excessive ripple voltage generated on the choke coil 7, the light emitting diode is lightened, and by the controlling circuit 2 via the photo-coupler 10, a device is worked to lower output voltage.
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