In a free-running inverter for a load, especially a low-voltage lamp, with a bridge rectifier circuit (2-5) which provides a rectified a.c. voltage to two output terminals (a1, a2), a series circuit comprising two controllable switches (10, 11) which connects the two output terminals (a1, a2) of the rectifier circuit, a series circuit comprising two capacitors (12; 13) arranged in parallel with the switches (10, 11), and a protective citcuit (F) which is connected to a current measuring instrument (E) for the load current and switches the inverter off at too high a load current, there is a voltage divider circuit (23-26) between the two input terminals of the rectifier circuit (2-5), and the supply voltage for the protective circuit (F) is taken between the central tapping of the voltage divider circuit (23-26) and an output terminal (a2) of the rectifier circuit (2-5).