Abstract: A parallel control type DC--DC converter supplies an output voltage to a load based on voltages supplied from independent power sources. The DC--DC converter is provided with at least first and second converters powered by the independent power sources and commonly grounded and including a switching element, a control circuit driving the switching elements within the first and second converters by ON-pulses having the same width depending the output voltage, and a circuit coupling outputs of the first and second converters in parallel and producing the output voltage.

Abstract: In a method and a device for determining and indicating a residual capacity of a battery, a charging amount is measured in a charging mode in which a charger having a sensor for detecting a fully charged state is connected to the battery. If the charging amount in the charging mode is more than a trickle charging amount, the measured charging amount is added to a present charging amount to obtain the present charging amount and a ratio of the present charging amount to a fully charged state is indicated on a display unit. If the charging amount in the charging mode is less than a trickle charging amount, it is judged that the present charging amount is the fully charged amount and this amount is the fully charged state. The device further includes a current-to-voltage converting circuit, an analog-to-digital converter, and an operation control unit such as a MPU connected to the display unit and executing and controlling the operation of the device.

Abstract: A voltage stabilizing circuit comprising a voltage detecting circuit for detecting a control voltage in response to an output voltage of the voltage stabilizing circuit, and a control circuit for stabilizing, based on the control voltage, the output voltage of the electronic device. To remove the component of a base-emitter voltage from the control voltage, the voltage detecting circuit includes a first series circuit and a second series circuit connected to each other in series. The first series circuit consists of a first resistor and a first transistor connected in series. The second series circuit consists of a second resistor and a second transistor connected in series. The second transistor is connected to function as a diode connection. The first resistor and the second resistor have substantially the same resistances. Thus the control voltage is made to be substantially the same as the output voltage.