Improvements in and relating to electric discharge tubes and lamps

摘要

416,388. Supplying discharge lamps. BRACKENSEY, A. H., and FRANCOBRITISH ELECTRICAL CO., Ltd., 25, Oxford Street, London. March 11, 1933, No. 7408. [Class 38 (iv).] The luminosity of a sign comprising one or more tubes is automatically varied by varying the impedance of a choke in the primary circuit without interrupting the illumination. In one form a choke is periodically short-circuited by means of a camoperated switch. In another form, a choke 1 has tapping 1 connected to brushes 1 bearing on a rotating cylinder 9 with a contact ring 11 and contact strip 10. A set of four tubes may be operated in two groups so as to produce animated or running effects without extinguishing any tube, each group comprising two tubes with their transformer primaries in parallel and a variable choke in series in the primary supply.