GB205058A - Improvements in and relating to electron discharge devices and circuit arrangements therefor - Google Patents

Abstract

205,058. British Thomson - Houston Co., Ltd., (Assignees of Hull, A. W.). Oct. 3, 1922, [Convention date]. Thermionic amplifiers and detectors. - A thermionic device comprises a main cathode, heated by electron discharge and radiation from an auxiliary cathode, a control electrode, and an anode, the auxiliary cathode being heated by current from part of the secondary of a transformer which is also connected with the anode. As shown in Fig. 1, the auxiliary cathode 2, preferably in the form of a straight filament surrounded by a cylindrical main cathode 5, is connected across part of the secondary 13, one end of which is connected with the cathode 5, and through a telephone receiver 16 with the anode 9, resistances 14 and condensers 15 being interposed as shown for smoothing out fluctuations in the current.. It is stated that with this system of connections rectified current is supplied to the anode. The outer surface of the cathode 5 may be coated with a thermionically active material so that electrons are emitted therefrom at a temperature low in comparison with that of the inner surface. In the device shown in Fig. 4 for obtaining rectification of both half waves, a coiled auxiliary filament 2 suspended on supports 17,. 18, 19 is heated from an ordinary lighting circuit, and the cylindrical main cathode 5 is provided with a flange 20 for shielding the electrons from the electrostatic field of the filament 2 and its supports. In the arrangement shown in Fig. 2, a valve is connected to the lamp socket, and the lighting circuit is used as a wireless receiving antenna. For this purpose a point on the transformer 22 is earthed and the main cathode 5 is connected through an inductance 23 and a variable condenser 24 to earth. The grid 7 is connected with the other end of the inductance, as shown. A retroactive coil 27 may be connected in the anode-cathode circuit.