D.c. compensation circuit for miniature transformers

Claim 1

A d.c. compensated electric transformer comprising primary and secondary windings, means for separating the windings of at least one side of said transformer into first and second electrical loops, means for introducing a d.c. voltage into said separated windings intermediate said first and second loops to thereby produce a first d.c. current in a first direction in said first loop, a d.c. compensation circuit coupled between said first and second loops for producing a second d.c. current in said second loop in a direction opposed to said first direction, said compensation circuit including first and second current balancing resistors coupled to ground potential, a diode having its anode coupled to said first resistor and its cathode coupled to said first loop, and a pnp transistor having its emitter coupled to said second resistor, its collector coupled to said second loop, and its base coupled to said first loop, the ampere-turn product of said first d.c. current in said first loop being substantially equal to the ampere-turn product of said second d.c. current in said second loop such that d.c. magnetic fields in said transformer are substantially cancelled, means for introducing a.c. signals into said first loop, and means through which said a.c. signals bypass said d.c. compensation circuit without substantial attenuation.