Abstract: A pulse generator with a low duty factor includes a capacitor arranged to alternately be charged via a first current path and discharged via a second current path, the second current path has a thyristor element with its anode-cathode circuit connected across the capacitor and is arranged to be activated by a predetermined capacitor voltage and to be deactivated by a second thyristor element. A resistor network has a first resistor means connected between the anodes of the thyristor elements and two second and third resistor means arranged to connect a pole of the capacitor to the anode of the first thyristor element and to the anode of the second thyristor element respectively. The second thyristor element is arranged to be provided with a trigger voltage generated across a cathode load of the first thyristor element.