Patent ID: 7250743

Claim:
A circuit for controlling a voltage applied to an output voltage terminal from a first voltage level supplied by an input voltage terminal comprising: a first switch and a second switch connected in series between said input voltage terminal and a common terminal; a first transformer, having a primary side and a second side, connected with said first switch on the primary side and to said output terminal on the secondary side, said first switch connected in parallel with said transformer; a second transformer connected between said input voltage terminal and said common terminal; and at least one tap switch connected between a secondary side of said second transformer and a common junction point between said first and second switches; wherein when said first switch is closed and said second switch open, said first voltage level is supplied to said output voltage terminal; wherein when said first switch is open and said second switch is closed, a second voltage level is supplied to said output voltage terminal; and wherein when said at least one tap switch further controls the voltage level being supplied to the output terminal high voltage winding.