GB404532A - Improvements in electrically operated sound signalling instruments employing vibrating diaphragms - Google Patents

Abstract

404,532. Electric horns. AUSTIN, L. J. F., Lichfield Chambers, Upper Priory, Birmingham. Sept. 7, 1932, No. 14833/33. Divided on 404,400. [Class 13.] The diaphragm of an electric horn is arranged to vibrate with an amplitude of the order of 0.01 inch and the armature is supported at the centre of a spring bridge fixed at its ends and having additional spring means arranged to counteract forces tending to tilt the armature. As shown, a baseplate j carries the hollow core a<1> of an electromagnet co-operating with an armature b carried at the centre of spaced blade springs c<1>, c<2>, c3 clamped at their ends to brackets p pressed up from the base plate j. A threaded rod d passing through the armature b and the hollow core a<1> strikes or is attached to the diaphragm e, and the springs c<1>, c<2>, c<3> with spacing members k and armature b are clamped together by a nut d<1> running on the rod d. One of the spacing members k is provided with bent over prongs k<1>, which bridge the stationary member f<1> of the contact breaker and engage the movable contact h, the armature being cut away opposite the contacts f<1>, h. The position of the fixed contact f may bo adjusted by the screw f<2>, and the trembler blade g carrying the contact h is covered with insulating material g<1> which is engaged by the prongs k<1>. The cover m is screwed to a bracket a attached to the baseplate and may house a battery. Specifications 381,227 and 404,400 are referred to.