Patent ID: 8487541

Claim:
A ballast circuit ( 6 ) with dual starting circuits for igniting a lamp ( 53 ) regardless of input half cycle, comprising: a first starting circuit ( 13 ) comprising a self-oscillating resonant circuit ( 10 ) that includes at least two lamp leads ( 50 , 52 ) and a resonant inductor ( 58 ) that induces a voltage proportional to an instantaneous rate of change of current in the resonant circuit ( 10 ) in two driving inductors ( 86 , 108 ) that drive first and second switches ( 70 , 72 ), the driving inductors being mutually coupled to the resonant inductor; and a second starting circuit comprising a bias resistor ( 11 ); wherein the bias resistor ( 11 ) causes the ballast circuit ( 6 ) to start regardless of whether the input half cycle is positive or negative.