Abstract: A device which enables a plurality of discharge lamps that are connected to a common ballast to be turned on and off separately via external switches. The operation circuit of the ballast is connected to the external switches through decouplers. The operation circuit may be supplied with voltage via any of the decouplers. A detector detects which of the switches has been closed and closes a logic member in the lamp circuit of the discharge lamp concerned. Consequently, the only lamp circuits that are closed are those in which the detectors have responded.

Abstract: A d.c. voltage supply circuit including a flyback converter having an inductor which is alternatingly charged through an electronic switch and discharged via a diode onto a capacitor. The output voltage of the flyback converter is continuously monitored. If a threshold value is exceeded, the electronic switch, which is mounted in an input line of the flyback converter, is changed into the off-state. The off-state of the electronic switch is terminated as soon as the output voltage has again fallen below the threshold value. Loads requiring a specific d.c. voltage may be connected to different supply voltages without the need of changeovers. The circuit offers a high security in view of overvoltage from the power network. It is self-monitoring and protects the connected load.

Abstract: A d.c. supply circuit containing a series-circuit composed of a switch and an inductor. A regulator circuit is provided to alternatingly drive the switch into conductive and nonconductive states. The control is performed by the inductor and responsive to current (i.sub.L).The series-circuit also includes an auxiliary switch, to which is connected, in parallel, a series-circuit formed by a diode and a capacitor. In short periods, in which the switch is conductive while the auxiliary switch is nonconductive, the capacitor is charged in order to generate the supply voltage for the regulator circuit.

Abstract: An elongated luminaire is provided having at least one fluorescent lamp and a louver arranged therebelow. The louver consists of lamp-parallel longitudinal reflectors and reflecting cross-oriented lamellae arranged transversely thereto and subsequently of V-shape in cross section. The lamella legs have a parabolic shape in cross section. A light guiding plate is provided extending from one leg of each cross-oriented lamella, extending diagonally upwardly towards and almost adjacent to the lamp. Each light guiding plate substantially overlaps the interspace between neighboring cross-oriented lamella in the vertical projection. Thus, the entire light flux, emerging downwards, is directed, depending on the position of the cross-oriented lamellae and of the light guiding plates, in the desired direction into the lower hemisphere so that it is possible to obtain different light distribution curves of symmetrical or asymmetrical shape with characteristic preferred directions.