A thyratron circuit for theater lighting

AT present there is a definite need in small theaters, such as those in colleges and universities, for a flexible, highly advanced system of stage lighting control. During recent years such systems capable of supplying the relatively tremendous loads of the large muscial comedy houses — up to about 25 kilowatts individual circuit capacity — have been developed. However, little attention has been paid to the needs of the small legitimate theater, which requires just as much flexibility of light control and perhaps almost as many circuits but of much smaller individual capacity — perhaps a kilowatt or two maximum. It is with circuits appropriated for this use that the present paper deals. Experimental circuits employing thyratrons as power rectifiers, supplying uni-directional current directly to a lamp load, were developed as part of the investigation and proved satisfactory. The fundamental problem in stage lighting is that of supplying voltages of proper magnitude to appropriate lamp circuits in the required sequence. Although it may be difficult to decide which single feature is most desirable in a satisfactory theater lighting control system, a number of characteristics are agreed to be essential, and their comprehension lies in a brief analysis of a few typical examples of the operator's task.