CONTROLLER OF CAPACITOR CHARGING CURRENT

摘要

PURPOSE: To obtain a charging current controlling effect which is the same one as available at the time of turning the power on even when the line voltage sharply changes by connecting a bipolar transistor in parallel with a resistor connected between a diode rectifying circuit and a smoothing capacitor and driving the bipolar transistor with constant and specified base current. CONSTITUTION: An npn transistor 6 is connected in parallel with a resistor 5 for controlling charging current which is inserted between a rectifying circuit 2 and a smoothing capacitor 3. The npn transistor 6 is driven with a constant base current IB which is allowed to flow in the transistor 6 by a base driving circuit 7. The base current IB is set to a constant value so that collector current IC in a driven zone of the transistor may be a specified value and larger than the rated current of a DC circuit. By this method, a power loss can be lessened in steady operation by effectively shorting the resistor 5 and charging current can be effectively controlled by a current controlling function of the transistor 6 in an active zone not only when the power is turned on but also when the line voltage changes.