PURPOSE:To apply a stable output voltage while suppressing the fluctuation of saturation voltage of an output transistor (TR) by operating independently each driver circuit to drive the output TR at a stable current at all times. CONSTITUTION:A base (base of a TR 6) is connected to an equivalent PNP TR (pseudo Darlington) comprising PNP TRs 6, 7 is connected to a bias circuit 29 formed by connecting a bias resistor 1 and the anode of a diode 5 and the other terminal of a bias resistor 1 is connected to the emitter of the equivalent PNP TR (connecting point of the emitter of the TR 6 and the collector of the TR 7) through a bias resistor 2. Thus, the base-emitter voltage of the TR 6 is subtracted from the potential of the bias circuit 29, and divided by the bias resistor 2 and supplied as nearly constant current as the driving current of the TR 8. Thus, the fluctuation of the saturation voltage of the output TR 8 is suppressed and the output voltage is made stable.
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