Patent GB-148133-A (GB)
Title: Improvements in and relating to electron discharge apparatus
IPC: H01J21/02
Filed: 1920-07-09
Abstract: 148,133. British Thomson - Houston Co., (Assignees of Langmuir, I.). Oct. 29, 1913, [Convention date]. Void [Published under Sect. 91 of the Act]. Vacuum tubes.-A highly-exhausted tube has an electron-emitting cathode, such as an incandescent filament, one or two anodes, an electrode which is maintained at a positive potential to reduce the space charge, and optionally one or two controlling grids. The arrangement may be used as an amplifier &c. in wireless systems, for rectifying, and for converting continuous into alternating current. In one arrangement, Fig. 1, a V-shaped cathode 2 is mounted in a glass frame 5 around which wire 6 is wound to form the electrode for neutralizing the space charge. Two grids 7, 8 consisting of wire wound around frames of ferro-chrome, and anodes 3, 4, secured by spring-supports 20 in extensions of the tube, are mounted on either side of the cathode. The wire may be of tungsten having a diameter of 0.0004 to 0.0010 inch, and is wound with about 100 turns to the inch. In the arrangement shown in Fig. 2, for converting continuous into alternating current, the electrode 6 is maintained positive by means of a battery 30, and the grids 7, 8 are connected to the secondary of a transformer 39, an intermediate point of which is connected with the cathode 2. The anodes 3, 4 are connected with the primary of a transformer 33, an intermediate point of which is connected with a source of continuous current such as a dynamo 34 or battery. The electron discharge passes alternately to the anodes 3, 4 by the action of the positive and negative potentials applied to the grids by the transformer 39, the frequency of the resulting current in the transformer 33 being the same as that in the transformer 39. A condenser 41 may be provided to absorb current variations and to neutralize the inductive effects of the transformer. A battery 75 may be connected as shown with its negative terminal to the transformer 39 to assist the action of the grids when becoming negatively charged, and resistances 77, 78 may be included in the grid circuits or a single resistance in the circuit 40. In an arrangement for rectifying alternating current, a cathode, surrounded by a space-charge neutralizing electrode, is mounted between two anodes connected with the primary of a transformer, an intermediate point of which is connected with one of the leads supplying the rectified current, the other lead being connected with the cathode. In another construction of tube for use as a rectifier, the positive neutralizing electrode is in the form of a flat ring interposed between the cathode and a disk anode, the electron discharge being focused to pass through the aperture in the ring by means of a negatively-charged cup-shaped electrode surrounding the cathode. In the arrangement shown in Fig. 5 for use in wireless receiving circuits, the grid 62 is maintained at a negative potential by a battery 66, which is connected through a transformer winding 63 with the anode 61. A low positive potential is applied to the anode by a battery 59 in circuit with a telephone receiver 70. A positively-charged electrode 67 surrounds the cathode.