Self-oscillating dimmable electronic ballast

This paper presents two simple alternatives of electronic ballast operating in self sustained oscillating mode with dimming capability for fluorescent lamps. A simple modification in the drive circuit allows dimming of the lamp. The describing function method and the extended Nyquist criterion are used in the analysis and the design. Experimental results from two 40 W electronic ballasts are presented to demonstrate the performance and to validate the analysis carried out.