GB594626A - Improvements in and relating to circuits for electric discharge lamps - Google Patents

Abstract

594,626. Supply systems for space discharge apparatus; transformers. GENERAL ELECTRIC CO., Ltd., and CATES, J. July 2, 1945, No. 16766. [Classes 38 (ii) and 38 (iv)] An electric discharge lamp 10, Fig. 1, has terminals 11, 12 connected through a condenser 13 between output terminal of a stray field transformer energized at terminals 17, 18. The transformer may comprise primary and secondary windings 21, 22 mounted on a central limb 23, Fig. 2, of a shell-type core, and has a flux leakage path between them provided by iron stampings 24 separated from the main core by air gaps 25 and an additional air gap 26 is provided in the path of the flux linking the secondary winding. In a modified form, Fig. 3, two E-shaped cores 30, 31 are used and are separated by non-magnetic material 32 to provide the air gap in the path of the flux linking the secondary winding 22. In a further modification, Fig. 4, the transformer comprises two approximately U-shaped cores 33, 34 preferably provided with two secondary windings 22 and 22<1> and two primary windings 21 and 21<1> respectively. Stampings 24 are provided between the limbs of core 34 and an air gap 35, between the two cores as shown. The primary and secondary windings 21, 21<1> and 22, 22<1> may be connected as an autotransformer. In an arrangement for operating an additional lamp 10<1>, Fig. 5, in a purely inductive circuit, the transformer of Fig. 2 is modified as shown in Fig. 6; two secondary windings 38, 39 being disposed on either side of a primary winding 37 and separated from it by stampings 41, 42. The secondary winding 38 may be connected to a tapping on the primary winding 37 in order to obtain substantially equal open circuit voltages from both secondaries. Each of the foregoing arrangements is applicable to hot or cold cathode discharge lamps and in each case the stray field transformer may be double wound.