A device for modifying an AC voltage has an input for connecting to an AC voltage source and an output for connecting to a load circuit. An interrupter is designed such that, within a time window, the output can be disconnected from the AC voltage source. The time window has a time delay from the zero crossing of the voltage of the AC voltage source. At the output, the device has a terminator that is designed, together with the interrupter, such that the voltage at the output has a predefined or predefinable value in the time window. The device also includes a pulse shape generator for generating a predetermined or predeterminable pulse shape, and a control that actuates the terminator and the interrupter such that the voltage curve at the output can be modified according to the pulse shape predetermined by the pulse shape generator.