Abstract: Disclosed herein is a switching power supply circuit that includes a switching circuit having an input node connected to an input power supply terminal and an output node connected to an output power supply terminal through an output switch, a feedback circuit configured to feed back information based on a voltage appearing at the output node to the switching circuit, and an activation circuit configured to turn ON the output switch after an elapse of a predetermined time after a voltage appearing at the output node exceeds a predetermined value. The switching circuit is configured to adjust a level of a voltage appearing at the output node based on the information to a predetermined level. The feedback circuit includes an adjustment mechanism configured to adjust a relation between a voltage appearing at the output node and the information.

Abstract: An electromagnetic induction power generator includes a magnetic core attachable to a power transmission/distribution line, a power generating coil wound around the magnetic core, and a switching power supply circuit that converts AC appearing at both ends of the power generating coil into DC. The switching power supply circuit stops its switching operation based on a DC voltage level. The stop of the switching operation increases reactive power, allowing a stable power generating operation, i.e., a stable supply of active power irrespective of the amount of current flowing through the power transmission/distribution line. In addition, the amount of the reactive power can be finely adjusted based on the length of a period during which the switching operation is stopped, allowing a finer control of the reactive power.