GB155854A - Improvements in application of thermionic valves to production of alternating currents and in relaying - Google Patents

Abstract

155,854. Eccles, W. H., and Jordan, F. W. April, 17, 1918. Vacuum or low-pressure apparatus, arrangements of.-In a method for generating alternating or fluctuating current from direct current, a moving member is arranged to produce, directly or indirectly, an alternating or fluctuating voltage in the control circuit of an ionic tube, so that corresponding variations arise in the current through the anode circuit of the tube. and these variations are used to sustain the motion of the moving member. In the arrangement shown in Fig. 1, the moving-member is a tuning-fork vibrating between two electromagnets A. B, one of which is in the grid circuit and the other in the anode circuit of the ionic tube. The movement of the grid prong sets up voltages in the grid circuit, and the corresponding variations in the anode current traverse the electromagnet B and sustain the vibration of the fork. The tuning fork may be replaced by an adjustable reed or by a lever carried by a spindle capable of torsional vibrations. Instead of exciting the control circuit directly by the mechanical movement of the vibrator, it may be excited indirectly, either wholly or in part, by induction from the anode circuit. Thus the electromagnets may have two windings, one in the anode circuit and the other in the grid circuit, or the electromagnet A may be replaced by a transformer with its primary winding in the anode circuit and its secondary in the grid circuit. The arrangement shown in Fig. 1 can be used as a tuned or selective relay, the primary winding of a transformer T in the anode or grid circuit being used to receive the alternating current to be detected. When used as a relay, the fork may be replaced by a mono-frequency telephone, the frequency of the moving diaphragm or other vibrator being determined by means of an associated circuit comprising an inductance and a condenser. In the arrangement shown in Fig. 5, the vibrations are sustained by electrostatic forces instead of magnetic forces, the electromagnets being replaced by flat conductors A, B in the grid and anode circuits respectively. In this arrangement, a vibrating reed is shown instead of a tuning fork, and a grid leak GL is provided. In another arrangement, Fig. 7, a rotating wheel D with iron teeth T is employed. This wheel may rotate in a horizontal plane between the poles of electromagnets in the grid and anode circuits respectively, the fluctuating currents set up in the anode circuit exerting on the teeth propelling forces which sustain the motion of the wheel. Indirect methods of exciting the grid circuit by induction frnm the anode circuit may be used or the grid circuit may be excited directly by means of a commutator on the spindle of the rotating wheel. Other forms of ionic tube, e.g. a two-electrode tube in which the control current is added to the filament-heating current, may be used.