GB149422A - Improvements in thermionic devices - Google Patents

Abstract

149,422. Fleming, J. A. May 12, 1919. Vacuum tubes.-A thermionic valve has two pairs of plates C, D, Fig. 1, arranged symmetrically around and close to a filament cathode B. The plates are of nickel or platinoid and may be in the form of segments of cylinders with the convex surfaces nearest the filament, and at a distance of 2 to 5 millimeters therefrom. The plates and filament may be mounted at one end of the bulb, the leads passing through glass tubes I, or the plates may be supported from the side of the bulb. The valve may be used as a detector &c. in wireless systems, the plates c, acting as " collectors " of the electrons, being connected through a galvanometer or telephone receiver F, Fig. 4, with the positive end of the filament battery E, the other plates D being connected either directly or through an air-core transformer with the closed receiving circuit L. The application of a difference of potential to the plates D causes the current in its circuit of the receiver &c. to be reduced. Two or more such valves may be connected in parallel. In the arrangement shown in Fig. 5, the plates C are connected with a relay M closing the circuit of a call-bell, lamp, recorder such as a Morse inker, or motor O operating a rudder, and the plates D are connected across a high resistance Q in the anode circuit of a 3- electrode valve U connected in a receiving circuit. Two or three such valves may be used for steering &c. a boat or an aeroplane from a distance by employing waves of different length. The arrangement may be employed as a detector in an alternating-current potentiometer or wheatstone bridge. Specification 24850/04 is referred to. According to the Provisional Specification, two of the plates are placed nearer the filament than the other two.