Fluorescent lamp controlling

Claim 1

Apparatus for energizing a fluorescent lamp having two filament electrodes comprising, a rectifier circuit responsive to an AC voltage for providing DC voltage, a transformer having at least a primary winding and secondary winding means for providing transformed power to said lamp, switching means for intermittently connecting said DC voltage to said primary winding to develop current pulses at an ultrasonic frequency, said switching means comprising a power transistor for providing a voltage waveform at the primary winding having peaks during every cycle, and a blocking diode for selectively isolating the primary winding form the power transistor, means for coupling said secondary winding means to said filament electrodes to both heat said filament electrodes and establish a potential thereacross for initiating and maintaining an arc therebetween said transformer including a feedback winding, said power transistor including a base, and a starting circuit having a resistor in series with a capacitor connected to said rectifier circuit and coupled through said feedback winding to said base to initially render said power transistor conductive, wherein the switching means comprises, a power MOSFET used as an on and off switch, a CMOS oscillator circuit oscillating at said switching frequency for controlling the state of the power MOSFET, and a snubber circuit for limiting the peak voltage across the power MOSFET.