Abstract: Pulse operating circuit for high intensity gaseous discharge lamps is provided with improved lamp starting device. The circuit comprises a direct current supply, a transistor switch in series with a ballast inductor and a lamp across the DC supply, an SCR switch connected across the inductor, a control circuit connected to the transistor switch for applying DC pulses to the lamp at a predetermined repetition rate and duty cycle, a sensing circuit for sensing the voltage across the inductor, and a variable SCR firing control circuit connected to the SCR and the first mentioned control circuit and responsive to the sensing circuit to control the firing of the SCR for limiting the peak current through the transistor switch during the lamp starting and warm-up interval.