GB160244A - Improvements in diaphragm and like vibrators operated by alternating electric current - Google Patents

Abstract

160,244. Bulle, M. P. Favre-, and Lavet, M. J. Dec. 13, 1919. Diaphragm vibrators.-An acoustic alarm comprises a box k, Fig. 1, of magnetic material having one or more coils energized by alternating current to produce a succession of impacts between soft iron cores c, d carried by the sides a, b of the box. The box may be of tinned iron, the sides acting as vibrating diaphragms when the coil is energized. In a modified construction, impacts are produced through the medium of a spring-controlled auxiliary core located axially within one of the soft iron cores. Fig. 3 shows a construction applicable when the conductor requires to be protected from damp &c. The bottom of the box consists of an iron casting t with a screw-threaded hole v to receive a union piece in connection with the insulating-pipes of the electric mains. To avoid over-heating, a fuse is arranged in the box, the core w is shaped as shown to allow a large surface of radiation of the coil u; and, in winding the coil, two conductors of unequal resistances such as copper and german-silver wire are employed, the copper wire being wound on first and covered by a few turns of the silver wire. Instead of a stamped box, diaphragms consisting of steel discs may be united at their periphery to the annular walls of the box.