GB259234A - Improvements in electric remote control systems - Google Patents

Abstract

259,234. British Thomson-Houston Co., Ltd., (Assignees of Alexanderson, E. F. W.). Oct. 1, 1925, [Convention date]. Switching systems.-A vapour device, for example a vapour rectifier, is provided with auxiliary electrodes for controlling its conductance, and impulses of predetermined frequency from a remote station are selectively utilized for impressing a controlling potential on the auxiliary electrodes. As shown in Fig. 1, the vapour device comprises a full-wave rectifier for converting alternating current in the mains 1 into continuous current in the circuit 2. The secondary coil of a transformer 4 has its ends connected to the anodes 7 of the rectifier 3, and the output leads 2 are connected respectively to the cathode 8 and the mid-point 6 of the transformer secondary. Exciting electrodes 9 are connected to the. ends of the secondary coil of an auxiliary transformer 11, which has its mid-point connected to the cathode 8. An auxiliary mercury electrode 19 serves for initiating the operation of the device. The rectifier is controlled by a circuit 20 which is connected on one side to the cathode 8 and on the other side through resistances 14 to the two control electrodes 12 in parallel. When the alternating voltages in the circuit 20 render the control electrodes 12 positive, the rectifier is operative. The voltages in the circuit 20 may be supplied from a receiving aerial 13 through a tuned detector 15 and lowfrequency amplifiers 16, 17 which transmit the modulation of the received wave to the circuit 20. A plurality of devices may be selectively controlled by employing different frequencies.