Abstract: Starting and operating circuit for gaseous discharge lamps having device for quickly restarting extinguished lamps while still hot includes means for reducing power supply voltage overshoot upon turn-on of the system. Circuit comprises a source of alternating current, an inductive regulator ballast having its input connected to the alternating current source, and a gaseous discharge lamp connected to the output of the ballast, a sine wave oscillator circuit having its input connected to the current supply and having its output connected to a transformer connected in series between the ballast and the lamp for stepping up and applying voltage to the lamp, a rectifier connected between the alternating current source and the oscillator circuit, the overshoot reducing means comprising a resistor connected between the rectifier and the oscillator circuit and a controlled switch for selectively connecting and disconnecting the resistor in the circuit.

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.

Abstract: Color properties of high pressure sodium vapor discharge lamps are improved by disclosed operating circuit for applying pulsed direct current to the lamp. The circuit comprises a direct current supply circuit, a transistor switch in series with a ballast inductor and a lamp across the supply circuit, an SCR switch connected across the inductor, a coasting diode across the inductor and lamp, and a control circuit connected to the switches for applying DC pulses to the lamp at a predetermined repetition rate and duty cycle. The circuit produces pulse waveforms which provide optimum color improvement in the lamp and makes efficient use of the energy supplied from the power source.

Abstract: Increased color temperature of high pressure sodium vapor discharge lamps is provided by improved operating circuit for applying pulsed direct current to the lamp. The circuit includes a direct current ballast circuit having low ripple factor and a pulsing circuit comprising a controlled thyristor switch which operates to apply DC pulses to the lamp at a predetermined repetition rate and duty cycle. The described circuit provides for gradual increase in power applied to the discharge lamp during the starting interval and thereby avoids instability of lamp operation during that stage.