Abstract: A multi-lamp protection circuit for an electronic ballast includes an inverter circuit of various types, and a transistor switch provided in the inverter circuit and connected to a plurality of lamp circuits, each lamp circuit connected respectively in series to a transistor switch and a disorder checking circuit. The signal got by the disorder checking circuits mixed with a control signal starts resonance transistors so as to checking disorder and separating the damaged lamp(s), lessening its producing cost and achieving normal efficiency of the lamps.

Abstract: A dynamic filter is interposed between the bridge rectifier and parallel-load resonant inverter of an electronic ballast. The dynamic filter circuit consists of two energy tanks and two energy transfer diodes and achieves power factor correction by performing input current shaping.

Abstract: A high power factor electronic stabilizer with projection circuit application comprising a high frequency filter between the input of a power source and a rectifying circuit, a feed-back power factor improving circuit between the rectifying circuit and an oscillating circuit for adjusting the angle of phase difference of the input current and voltage to the minimum to obtain the best power factor by taking a high frequency voltage from a lamp and feeding back to the output of the rectifying circuit and by switching a high frequency by means of the high frequency filter and the feed-back power factor improving circuit, and a protective circuit connected between the oscillating circuit and the feed-back power improving circuit for protecting the electronic stabilizer to elevate its quality and service life, turning off the transistors in case of the lamp getting out of order.