Patent ID: 7274574

Claim:
A circuit having a variable transformer, a current transformer, and a feedback circuit for supplying a feedback controlled current to a load wherein; said variable transformer consists of: a magnetic core upon which is wound at least one primary coil for receiving an input voltage; said magnetic core additionally having at least one secondary coil for supplying an output voltage proportional to a turns ratio defined by the number of turns of the secondary coil in the numerator to the number of turns of the primary coil in the denominator and a primary current; said magnetic core being fabricated from a magnetically soft material; a control coil proximate to and physically isolated from the magnetic core of said variable transformer wherein said physical isolation of said control coil beneficially assures electrical isolation from said primary coil and said secondary coil of said variable transformer; said control coil receiving a control current from said feedback circuit wherein said control current generates a magnetic field; said magnetic field causing a change in permeability of the magnetic core of said variable transformer in a physically non-coupled manner wherein said permeability in said magnetic core is increased as said control current in said control coil increases; said output voltage of said variable transformer decreases with the increase of said permeability; said current transformer having at least one primary winding and a plurality of secondary windings: said primary winding of the current transformer receiving a current from the secondary coil of the variable transformer; wherein a first secondary winding serving to provide a feedback current to the control coil of said variable transformer; additional secondary windings being optionally provided for input to one of the group consisting of an external controller, a microprocessor, and a monitoring system; and said feedback circuit useful for conditioning said feedback current from said current transformer and being chosen from the group consisting of a DC coupled feedback and control circuit, an AC coupled feedback and control circuit, and an optically coupled microprocessor feedback and control circuit.