Power supply unit

摘要

The invention relates to a power supply unit having an isolating transformer, which has a detection circuit for automatically detecting the instantaneous mains voltage. The detection circuit produces a switching signal which is supplied to an electrical switching device which then switches the isolating transformer to the correct configuration for the instantaneous mains voltage. In the detection circuit, a comparator in conjunction with an RC element ensures that the isolating transformer is initially set to the higher mains voltage range after being switched on.