In various embodiments, a power supply device for light sources may include a feed line from mains via a phase-cut dimmer, selectively switchable between a conductive state and a non-conductive state, to permit or interrupt feeding of the device from mains. The device may include a power stage to feed at least one light source from said feed line from mains; a drive stage for said power stage; and a supply stage for said drive stage, said supply stage connected to said feed line from mains. The device may further include a sensor to detect when said dimmer is non-conductive and when said dimmer is conductive. The drive stage may be coupled to the sensor to disable driving of said power stage when the sensor indicates that the dimmer is non-conductive, and enable driving of the power stage when the sensor indicates that the dimmer is conductive.