GB754993A - Improvements in or relating to circuits comprising two gas and/or vapour filled electric discharge tubes - Google Patents

Abstract

754,993. Supply systems for space discharge tubes. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Sept. 24, 1954 [Sept. 28, 1953], No. 27658/54. Class 38 (4). In a circuit comprising both a capacitively- and an inductively-stabilized gas and/or vapour filled electric discharge tube 1, 2 each having thermionic electrodes 11, 12 and 21, 22 connected to windings 13, 14 and 23, 24 of a heatercurrent supply transformer 8 whose primary winding 9 is serially connected with the stabilizing impedance 7 of the inductively stabilized tube 2 across the circuit supply terminals 3, 4, the capacitively stabilized tube 1 is serially connected with part of said stabilizing impedance 7 of the inductively stabilized tube 1 across the supply terminals 3, 4, and the heater-current windings 13, 14 of the capacitive tube 1 are connected in such polarity and are so dimensioned that the voltage set up across tube 1 is, prior to ignition, higher than that across the supply terminals, and the voltage set up across the tube 2 is not higher than that across the primary winding 9. Thus the capacitively stabilized tube 1 is caused to ignite first, whereupon its discharge current by flowing through the part of the inductance 7 increases the voltage across the inductively stabilized tube 2 which then ignites. The windings 13, 14 have more turns than the windings 23, 24 and during operation all the heater current secondary winding voltages are directed in the same sense as the operating voltage of the inductively stabilized tube 2. The positions of the elements 5, 6 of the capacitive ballast may be mutually reversed, and the tubes may be of the L.P. mercury vapour type having provided on their walls a fluorescent coating and an ignition electrode connected either to earth or to one electrode.