Abstract: Disclosed is a switching-type constant current power supply, which comprises an alteration circuit 9 provided on the output side of a power conversion circuit 3 together with a voltage detection circuit 7, and a feedback circuit 8 provided between the voltage detection circuit 7, a current detection circuit 5 and a control circuit 4. The alteration circuit 9 is operable, during a current flow period where a load current IL is flowing, to set the signal level of a second feedback signal F2 at a value less than a reference voltage Vref to be supplied to a common error amplifier EA1 in a control circuit 4, and operable, during a current cut-off period where the load current IL is not flowing, to set the signal level of the second feedback signal F2 at a value greater than the reference voltage Vref.

Abstract: Disclosed is a switching-type constant current power supply, which comprises an alteration circuit 9 provided on the output side of a power conversion circuit 3 together with a voltage detection circuit 7, and a feedback circuit 8 provided between the voltage detection circuit 7, a current detection circuit 5 and a control circuit 4.

Abstract: In prior art, the operation of the switching transistors Q1 and Q2 is within a range of class-AB to class-B and they are not good at efficiency since it is difficult to change the operating point thereof. There is disclosed an innovative switching power circuit which is self-oscillated by a tertiary winding N3 so that each of the pair of switching elements Q1 and Q2 may be conducted alternately and thereby a current flowing from the centertap is switched so as to selectively flow alternately to one side of the primary winding N1 or to other side thereof to generate an AC voltage on a secondary winding N2, said switching power circuit characterized by that an operating point of the switching elements Q1, Q2 is changed from that in starting by using a DC voltage generated by a switching operation of the switching elements Q1, Q2 as an inverse bias power source for the switching elements Q1, Q2.