Abstract: A circuit arrangement for A.C. operation of high-pressure gas discharge lamps comprising a mains alternating voltage source and a high-frequency oscillator (3) supplied with direct current and which produces a high-frequency current through the lamp superimposed on the mains alternating lamp current. The oscillator comprises a high-frequency transformer (7) and a transistor (11) connected in series with the transformer primary (8). The transistor can be periodically switched on an off. A secondary (9) of the transformer is connected in series with the lamp. Losses are reduced if the ratio between the switching-on and switching-off time (duty cycle) of the transistor (11) is chosen so small that the effective value of the high-frequency current coupled into the lamp lies between 0.05 and 5% of the mains alternating lamp current. An auxiliary device (16 to 19, 25) interrupts the periodic switching of the transistor (11) outside the proximity of the zero passages of the mains alternating lamp current.

Abstract: A circuit arrangement for adjusting the operating voltage of high-pressure gas discharge lamps to a given nominal value, comprises a controllable current limiter connected in series with the lamp and an adjustment circuit (3) for controlling the latter. The output signal of the adjustment circuit is determined by the difference between a given desired value determining the nominal lamp operating voltage and an actual value dependent upon the instantaneous lamp operating voltage. In parallel with the lamp (1) a heating element (5) is arranged which is in thermal contact with a temperature-dependent electrical element (6), which produces the actual voltage dependent upon the instantaneous lamp operating voltage.

Abstract: An electrode having a self-supporting cylindrical open coil of tungsten or molybdenum wire having a lead wire of tungsten or molybdenum passed coaxially through the coil and connected thereto. The turns of the coil engage each other. The central lead wire has a smaller diameter than the coil wire, this thin portion extending to a location just before the outermost turn of the coil.

Abstract: A circuit arrangement for operating a high-pressure gas discharge lamp (3) with a pulsatory direct current produced from an alternating voltage supply (A, B) via a full-wave rectifier (1). The output of the full-wave rectifier is shunted by a series arrangement of a diode (4) and a capacitor (5). The capacitor (5) has a value of 10 nF to 1 .mu.F and a resistor (6), which is high-ohmic with respect to a current limiter (2) in series with the lamp (3), is connected in a current circuit between the end of the capacitor facing the diode and the lamp (3). As a result, a low re-ignition voltage is attained during the head-up phase of the lamp.

Abstract: A method of operating a high-pressure metal vapor discharge lamp at a periodic operating voltage of more than 500 Hz wherein the operating voltage is suddenly varied in phase at intervals, and preferably also wobbled in frequency, in order to avoid acoustic resonances in the lamp.

Abstract: In a high-pressure discharge lamp having a straight tubular intermediate part (10) of quartz, glass or another material of poor thermal conduction arranged between the outer bulb (4) and the lamp base (7), the intermediate part is folded into the shape of a bellow. With respect to a cylindrical intermediate part, the length of the lamp is thus decreased.

Abstract: A circuit arrangement for operating high-pressure gas discharge lamps (6) with a current of higher frequency comprising a switching mains section including a switching transistor (4) and a control device (9), in which an upper and a lower reference current level (O,U) are produced. The switching transistor is switched to the non-conducting state when the lamp current exceeds the upper level (O) and is switched to the conducting state when this current falls below the lower level (U). The interval between the reference current levels (O,U) is more than 10% of the average lamp current and a further intermediate reference current level (M) is provided at which the switching transistor is switched each time at a predetermined number of passages of the lamp current through the intermediate reference current level.

Abstract: A circuit arrangement for starting and operating a high-pressure gas discharge lamp having an outer starting electrode connected to an igniter. A full-wave rectifier (1) is connected to an alternating voltage supply (A, B) and has an output shunted by a series arrangement of a diode (4) and a capacitor (5). The capacitor is discharged in part through the lamp (3) after each half period of the alternating voltage. A resistor (6), which is high-ohmic with respect to a current limiter (2), is connected in the current circuit between the end of the capacitor (5) facing the diode (4) and the lamp (3). Thus, starting of the lamp is facilitated.

Abstract: A circuit arrangement for operating a high-pressure gas discharge lamp (14) with high frequency current in which a direct voltage is supplied to a transistor bridge (5 to 8) having a transverse branch in which is arranged a choke coil (13). The clock (switching) frequency of the transistor bridge is varied within each period of the AC mains alternating voltage in dependence upon the current derived from the AC mains voltage.