Abstract: In a lighting installation comprising light sources each connected to an A.C. supply system, a control device including: power variation circuits connected to the different sources and each comprising means for varying the electrical power supplied to the respective source, in response to magnitude variations of an electrical quantity, and control circuits associated to the different sources and each comprising a clock circuit, an illuminating programme circuit in which is recorded a programme representing desired timed variations of the illuminating power for a given period, a selection circuit receiving clock pulses from the clock circuit and connected to the programme circuit for selecting an illuminating power dependent on the elapsed time from the beginning of said period, and an output circuit for converting said selected power to a particular magnitude of said electrical quantity.

Abstract: A control device for a discharge lamp, comprising an electronic switch connected between an AC supply source and a loading circuit including the discharge lamp to be controlled, and a control circuit delivering pulses to a control electrode of the switch so as to control the state of conduction thereof; the control circuit comprises means for detecting the passages through zero of the voltage at the terminals of the loading circuit and generating means responsive to the detecting means for generating pulses controlling the passage of the switch to the non-conductive state, whereby non-conduction periods of the switch are controlled for an adjustable duration in response to the passages through zero of the voltage at the terminals of the loading circuit.