GB564396A - Improvements in and relating to electric valve converting apparatus - Google Patents

Abstract

564,396. Converting. BRITISH THOMSON-HOUSTON CO., Ltd. (General Electric Co.). March 24, 1943, No. 4773. [Class 38 (ii)] An A.C. supply 3 is converted into D.C. 1, 2 by valves 5, 6, 7 having control members 14 of the immersion-igniter type which are excited. by peaked impulses of current from a resonant circuit such as 20, 21 having a natural frequency substantially greater than that of the supply circuit. In the form shown, a discharge device 23 in the resonant circuit allows current to pass to the control member 14 in the right direction only when its grid 24 has a positive potential which is when the current in a winding 29 is at its peak value and overpowers the battery 32. The exact timing-of the impulse may be adjusted by a phase shifter 27 and its duration is short because of the high natural frequency of the circuit 20, 21. In a modification, Fig. 4 (not shown), a second discharge device oppositely arranged, is placed in parallel with the valve 23 and the cathode .13 so that the resonant circuit may oscillate and produce a series of impulses at 14, till the starting of current in the valve 5 biasses the grid of the discharge device so as to render it non-conducting. In another modification, Fig. 5 (not shown), the resonant circuit is energized from the same transformer 4 that supplies the valves 5, 6, 7, and two discharge devices are connected in series with the control member 14, one becoming conductive at the precise time desired substantially as in the previous arrangement and the other becoming conductive when the condenser 21 forming part of the resonant circuit becomes sufficiently charged.