Adjustable electronic ballast

The utility model relates to an adjustable electronic ballast. The utility model has the main technical points that in an oscillating circuit, capacitors and adjustable inductance are connected in series to form a series resonant circuit which is connected between filaments and the inductance in series, wherein, an induction coil has the structure that the center of a skeleton of the induction coil has a cylindrical ventilation hole with internal threads; the outer part of a cylindrical ferrite core is provided with threads, and the cylindrical ferrite core is screwed in the ventilation hole of the coil. The center of the magnetic core has two square ventilation openings which are communicated. Compared with the existing electronic ballasts, the utility model has equal cubage and inductive impedance because the adjustable inductance coil is added.. The reliability of the utility model is ensured because the operating point can be in resonant region; thus, the stability and the product quality are enhanced.