A circuit includes a rectifier, e.g., including four diodes; a semiconductor switch; a coil that is chargeable, is dischargeable, and has (a) a first terminal connected to a first output terminal of the rectifier and (b) a second terminal connected via the semiconductor switch to a second output terminal of the rectifier; a first resistor via which a control terminal of the semiconductor switch is connected to the first output terminal of the rectifier; a second resistor connected between the second output terminal of the rectifier and the control terminal of the semiconductor switch; and a discharge unit connected between the second terminal of the coil and the control terminal of the semiconductor switch. The charging and discharging is implemented by, respectively, connecting both of, and disconnecting one or both of, first and second input terminals of the rectifier to/from the voltage source.