GB273398A - Improvements in or relating to electrically maintained tuning forks or reeds - Google Patents

Abstract

273,398. Muirhead & Co., Ltd., Muirhead, F. H., Neurtley, E. S., and Foll, J. V. March 31, 1926. Electromagnetic interrupters. - A tuning fork or reed A is maintained in oscillation electromagnetically by means of an electromagnet b<1> arranged to exert a pull upon the tines transverse to the direction of oscillation the electromagnet being energized intermittently by a contact a on one of the tines which engages, at the limit of the movement in both direction, with a fixed contact c in the energizing circuit of the electromagnet. Thus the tines are drawn electromagnetically from both their extreme positions towards the normal or central position. In order to obtain fine adjustments of periodicity as is necessary when the forks are used in synchronous telegraphy the position of the electromagnet in relation to the ends of the fork may be varied by means of the screwed spindle E and by supplying the electromagnet through a second winding with a constant excitation which may be adjusted by means of the resistance d. A permanent magnet adjustable along the tines may be used for the same purpose. In modifications an electromagnet with four poles or two electromagnets with two poles each may be arranged to be adjustable together along the tines of the fork.