The invention provides a conversion circuit for converting first signals coming from a fluorescent ballast into second signals for feeding a light circuit via a rectifier circuit, the light circuit comprising at least one light emitting diode. The conversion circuit has an inductor in a parallel branch between the two-terminal input or the two-terminal output. This enables the ballast output power be reduced without significant increase in losses. The conversion circuit is for enabling retrofit of LEDs to fluorescent ballasts.