DIMMING CIRCUIT FOR POWERING GAS DISCHARGE LAMPS

摘要

A ballast circuit uses an optocoupler to provide electrical isolation of the dimming control from the remainder of the ballast. The optocoupler is operated in the linear range to provide continuous dimming of the lamps. The circuit further uses a combination of diodes and a diode bridge to steer current from the current sensor during lamp out conditions so that the inverter will maintain operation at a low frequency, thereby maximizing the output voltage. A clamp winding is used to insure that the voltage does not exceed the DC rail voltage.