Abstract: A switching regulator comprises a single transformer having a primary winding connected in an input circuit for receiving direct-current energy and a secondary winding connected in an output circuit, and a switching transistor connected in series with the primary winding. A high frequency pulse generator triggers the switching transistor so that it interrupts the direct-current energy at a high frequency. A rectifier is provided for converting high frequency energy developed in the secondary winding into direct-current output energy, which is maintained constant by controlling the high frequency pulse generator. A low voltage detector produces a signal when the direct-current energy in the input circuit falls below a specified value. In response to the signal from the low voltage detector, constant direct-current energy is derived from a battery and applied to the output circuit as backup power.

Abstract: According to this invention, a converter includes a voltage transformer, a switching transistor, a resistor, a control transistor, and a control circuit. The voltage transformer has a primary winding, a secondary winding, and a control winding. The switching transistor is connected in series with the primary winding. The resistor is connected between the switching transistor and one terminal of an input power source. The control transistor has a base connected to a connection point between the resistor and the switching transistor and a collector connected to a control electrode of the switching transistor. The control circuit controls the control transistor on the basis of a control voltage extracted from the control winding.