Patent attributes
Ballast comprising input terminals receiving a DC voltage coming from a supply source on the vehicle, a chopping supply circuit functioning at a predetermined chopping frequency in order to supply as an output a voltage supplying the discharge lamp, and a filtering device disposed at the input and intended to reduce radio interference produced by the chopping supply circuit. The chopping supply circuit comprises at least one first filtering capacitor connected between the input terminals and a filtering choke connected in series between one of the input terminals and the chopping supply circuit. In accordance with the invention, the ballast comprises a filtering device which also comprises at least one second filtering capacitor in series with an additional choke. This second capacitor forms with the additional choke a resonance circuit situated between the input terminals and tuned to the chopping frequency.
