GB305574A - - Google Patents

Abstract

305,574. Westinghouse Lamp Co., (Assignees of Rentschler, H. C.). Feb. 7, 1928, [Convention date]. Vacuum tubes.-A vacuum tube serving as a relay is provided with two anodes and a cold cathode, a main anode 3 at some distance from the cathode 2 and a starting anode 4 close to the cathode. The resistance of the tube is broken down by a small current from the starting anode, permitting a larger current to pass from the main anode; the voltage between the auxiliary anode and the cathode may be greater than that between the main anode and the cathode. The tube may be filled with argon at a pressure from 5 to 8 millimeters of mercury, in which case the starting anode may be one millimeter from the cathode, which is one or two inches in diameter with the main anode in the centre, or from a projection 9 thereon. The starting anode may be coated with an active material such as thorium, titanium or uranium, which may have a further coating of barium oxide. The cathode may be coated with a metal of the alkalies, or alkaline earths, or with misch metal. In the arrangement shown, the starting anode is supplied with current from the main circuit 10 through a thermostatic switch 16 and resistance 15, the current from the main anode actuating an electromagnetic relay 13. Other arrangements are described in which the auxiliarv anode current is started by a photo-electric device or by varying the capacity of a condenser. Specifications 175,258, 217,230, and 287,578 are referred to.