Patent ID: 6366029
Filing Date: 2002-04-02
Classification: H05B,Y10S

Abstract:
A ballast circuit for supplying AC voltage and current to a gas discharge lamp mounted in a troffer upon the application of DC voltage and current, said troffer having a ground connection, said circuit comprising:a transformer including a first and a second primary winding; first and second transistors, each having base, collector and emitter terminals, said base terminal of each said transistor coupled to a drive terminal of said second primary winding; a constant current flow network coupled to said drive terminal so as to maintain said circuit in an oscillating mode; said first primary winding configured to be coupled across said at least one lamp such that a capacitance at a first end of said lamp relative to said transformer is equal to a capacitance at a second end of said lamp relative to said transformer; and a current supply source coupled to said troffer ground connection; wherein a net current induced via said at least one lamp and said current supply source into said troffer is substantially equal to zero.