Portable electric automotive engine cranking unit

A power supply for providing direct electrical current to a pair of electrical input terminals from an alternating electrical current source, said power supply including:

• a transformer having a primary and a center-tapped three terminal, secondary winding;
• means to connect the primary of the transformer to the alternating current source;
• a pair of semiconductor devices each having first and second main current carrying electrodes and a gate electrode;
• a pair of output cables;
• means for connecting an exterior end of each of said output cables to a separate one of the pair of engine electrical input terminals;
• an interior end of a first of said output cables being electrically connected to the center terminal of said transformer secondary winding;
• the first main current carrying electrodes of each of said semiconductors being connected to a separate one of the outside terminals of the transformer secondary winding;
• the second main current carrying electrodes of each of said semiconductors being connected together and to an interior end of a second of said output cables;
• a gate control circuit connected to the gate electrodes of said semiconductor devices;
• switch means connected into said gate control circuit to selectively cause said gate control circuit to switch said semiconductor devices into conduction;
• an outer case encompassing said transformer, said semiconductor devices and said gate control circuit;
• a block of solid, thermally stable, thermally conductive material intimately encompassing said transformer, semiconductor devices and gate control circuit elements inside said case, said thermally conductive material being in heat transfer relation with respect to said elements;
• said case being made of thermally conductive material and being in intimate, heat transfer relationship with respect to said solid thermally conductive material;
• a normally closed thermal limit switch embedded in said thermally conductive material, said limit switch being in series with the gate control circuit;
• p1 said means to connect the transformer primary to an alternating current source and said output cables each extending from position inside said case to the outside thereof for a sufficient distance to simultaneously connect to said alternating current source and to said engine input terminals, respectively;
• and
• said switch means including a pair of electrical control lines extending from said gate control circuit inside of said case to the outside thereof, and including a normally open, manually closeable switching device outside of said case and connected between said control lines, said electrical control lines being of a length sufficient that the switching device can be positioned remote from the exterior ends of said input cables and adjacent the location of the operating controls of said engine when said transformer primary is connected to an alternating current source and said output cables are connected to said engine electrical input terminals.

A power supply for providing direct electrical current to a pair of electrical input terminals from an alternating electrical current source, said power supply including:

• a transformer having a primary and a center-tapped, three terminal, secondary winding;
• means to connect the primary of the transformer to the alternating current source;
• p1 a pair of semiconductor devices each having first and second main current carrying electrodes and a gate electrode;
• a pair of output cables;
• means for connecting an exterior end of each of said output cables to a separate one of the pair of engine electrical input terminals;
• an interior end of a first of said output cables being electrically connected to the center terminal of said transformer secondary winding;
• the first main current carrying electrodes of each of said semiconductors being connected to a separate one of the outside terminals of the transformer secondary winding;
• the second main current carrying electrodes of each of said semiconductors being connected together and to an interior end of a second of said output cables;
• a gate control circuit connected to the gate electrodes;
• and
• operator controlled multiple contact switch means having ON/OFF contacts and momentary ON contacts connected into said gate control circuit to cause the gate control circuit to switch said semiconductor devices into conduction when either the ON/OFF contacts or the momentary ON contacts are in an ON position.