Abstract: AC power is converted to a low-voltage, high-current DC output by a power supply which contains two stages. The first stage is an AC to DC converter using a full wave bridge rectifier to convert the voltage from the AC source to an intermediate raw DC voltage. The second stage is a DC to DC forward converter using a transformer with its primary winding connected to the intermediate raw DC voltage through a switch which is cycled "on" and "off" at a predetermined frequency. During the switch "on" portions of the cycle a current flows in the primary winding powering the output and charging an inductor which is connected to the secondary winding. When the switch is turned "off", no current flows through the transformer and the load is powered by the energy stored in the inductor. A secondary coil is magnetically coupled to the inductor and has a induced voltage proportional to the output voltage.

Abstract: A battery saver circuit compares the battery terminal voltage to a programmable reference voltage and disconnects the battery from the load when the measured battery voltage falls below a predetermined minimum value. The reference voltage is programmable by a transfer function generator which varies the reference voltage in accordance with the current drawn by the load to account for the voltage drop in the line series wiring. A fault indicator is included to prevent chatter in the relay by raising the battery voltage necessary to reconnect the battery to the load. The fault indicator is reset when the battery is recharged.

Abstract: Overload protection for an AC/DC converter is formed by a high frequency AC power signal provided to a step-down/isolator circuit which converts the power signal to a low voltage signal. An output filter stage then converts the low voltage AC signal to a DC output for use in DC devices. Upon the occurrence of a short circuit or a current overload, the step-down/isolator circuit core becomes saturated, ceasing operation of the step-down/isolator until the short or the connected device drawing the current overload is removed.

Abstract: An adapter for supplying D.C. current from a lighter receptacle to a remote accessory is formed by a plug inserted into the receptacle which has a reversible interconnection with a cable connected to the remote accessory. The end of the cable with the reversible interconnector is marked to visually display the electrical polarity of current supplied to the remote accessory.