CIRCUIT AND METHOD FOR PREHEATING FILAMENTS AND BALLAST

摘要

The present invention provides a circuit and a method for preheating filaments and a ballast. The circuit for preheating filaments includes: a transistor; a first winding, one terminal of which being electrically connected with a collector of the transistor, and the other terminal being connected to an input of a power source; a second winding, one terminal of which being electrically connected with an emitter of the transistor, the other terminal being electrically connected with a base of the transistor, and the second winding being coupled with the first winding in a self-excitation mode; one or more load windings respectively connected with the filaments in series, and each of which being coupled with the first winding in a flyback mode; and a delay switch, which changes into an on state from an off state when a trigger signal with a predetermined delay is received, so as to turn off the transistor. There is also provided a method for preheating filaments and a ballast. The circuit for preheating filaments may save energy consumption and the cost is low.