1. A circuit arrangement for operating semiconductor light sources comprising:a power input for inputting an AC input voltage,
an output having a first output terminal, and a second output terminal, which is designed to connect a string of semiconductor light sources,
a control input for controlling the operation of the circuit arrangement with a control signal,
a rectifier circuit for converting the AC input voltage into a rectified voltage,
a converter circuit for transforming the rectified voltage into a current which is suitable for the semiconductor light sources,
a first switch arranged between the converter circuit and the output, for the switching of the current through the semiconductor light sources,
a first diode arranged between the first switch and the output, and
a second switch which is arranged between the converter circuit and the first output terminal, wherein the first switch is arranged between the converter circuit and the second output terminal.