To enable an output control of a power supply part from the load part side by a simple and low-cost circuit configuration.
An oscillation control means comprising a parallel circuit made up of resistance R21, a diode D2 and a transistor Tr1, and a control circuit 23 is provided to a load part 20. By making variable a magnetic flux generated in the primary coil Nf1 for signal transmission by turning on/off the transistor Tr1 by the control circuit 23, the oscillation control of the self-excited oscillation circuit of a power supply part 10 can be implemented. At charge of a secondary battery which is a load or the like, for example, the transistor Tr1 is turned off by the control circuit 23 to stop power supply from the power supply part 10 after charging with full, thereby stopping overcharge to prevent malfunctions such as damage to the secondary battery.
ABE HIDEAKI
KATSURA KASHIKI
