Abstract: A direct current power supply circuit converts an unregulated direct current input source such as an automobile battery to a regulated direct current output voltage for a device such as a mobile telephone requiring a fixed operating voltage. The circuit has an improved input to output voltage rating of less than two volts, enabling it to supply a load reliably with direct current power from an unregulated direct current source as low as ten volts. The circuit operates in a linear mode at low power levels and in a switching, pulse width modulated mode at higher output power levels. The circuit employs a three-terminal linear voltage regulator as a control element. It has input, output, and ground pins and is effective in response to current input through the input pin to maintain a predetermined, fixed voltage differential between the output and ground pins. In the example disclosed, the linear voltage regulator maintains a 5-volt differential between the output and ground pins.

Abstract: Improved automobile cigarette lighter male accessory adaptor plug and female receptacle connector assemblies are disclosed whereby a vehicle's electrical system is adapted to operate a variety of remote electrical devices and appliances. Both the male plug and female receptacle are constructed as unitary connector assemblies incorporating in-line fuse holders receptive of miniature, generally flat, insert type fuses having visable fuse links and extending blade terminals; the fuse being openingly accessible at the exterior of the connector assembly whereby the same is air cooled and is readily visable and removeable for inspection or replacement without disassembly of the connector.