Fluorescent electronic ballast circuits and products using the circuits

The present invention relates to an electronic ballast and its improved circuit, including interference-proof bridge rectifier circuit, semi-bridge switch change circuit, transformer output working circuit and circuit for raising power factor, the latter consists of high-voltage feedback circuit and circuit resisting harmonic reflection. The voltage feedback signal is taken from lamp tube workingloop, delivered from current transformer, coupled with capacitor, and fed back to the centre between two diodes which are forward serialized and combined with power filter capacitor so as to make input current waveform approach sine-wave, so that the power factor is raised to above 0.99, and total harmonic wave can be controlled within 4%. Said invented circuit and its electronic ballast can be used in fluorescent lamp lighting.