Ballasting network with integral trap

摘要

The invention provides a ballast circuit for fluorescent lamps that includes a high frequency trap and an impedance-transforming network which is coupled to the AC power source by the trap and which can be connected to the lamp or lamps, or other non-linear or negative resistance load. The trap comprises a parallel-resonant combination of an inductor and a capacitor and resonates at a selected frequency to cause a switching-circuit transistor or transistors to switch at times when the level of the current therein and/or the voltage developed across the circuit is zero. The frequency is, preferably, slightly higher than a harmonic frequency of the AC power source.