Abstract: The present invention concerns systems in which a plurality of device can be monitored. More particularly the invention concerns a monitoring system particularly though not exclusively for light dimmers in which requests for data are inserted into the gaps of periodic firing signals so as to trigger responses. Examples include dimming systems for use in theaters and in television and film studios.

Abstract: A lamp assembly particularly for a luminaire comprising a lamp having a light emitting member of generally torroidal shape and a reflector positioned and shaped to reflect light received from the light emitting member through the central opening. The light emitting member is preferably a filament of an incandescent lamp. The reflector has a cross-section comprising first and second arcs which are substantially symmetrical with respect to a line joining the center of the reflector and a point substantially at the centre of the torroidal member and the shape of the reflector is that described by rotating said arcs about said line. The arcs may be elliptical or circular for example with their foci or centers positioned to achieve the required effect.

Abstract: In a lighting power controller having a controllable switch (such as a thyristor), in order to compensate for perturbations in the mains supply waveform, the waveform is analyzed and a table is set up of thyristor firing angle against output RMS voltage. To obtain a desired output RMS voltage, the thyristor is fired at the angle indicated by the table.