The Electrical Control of Lamp Light Output

Abstract

The basis of all electrical dimming systems is that the light output of an electric lamp varies with the current passing through it. Three methods may be recognised, namely, resistive, inductive and electronic; all are applicable, singly or in combination, to both incandescent and discharge lamps.

For theatrical work using incandescent lamps, the thyristor permits dimming systems with highly organised control arrangements. The greater difficulties inherent in discharge lamps can also be overcome, so that fluorescent tubes, in particular, can be controlled with precision.

Inexpensive automatic control of interior lighting linked to daylight offers intriguing uses particularly as applied to permanent supplementary artificial lighting.