| 摘要 |
<p>1,044,733. Electric buzzers. V. & E. FRIEDLAND Ltd., and J. DOGGART. May 25, 1965 [June 4, 1964], No. 23260/64. Heading G5J. Coil 23 with its core 25 oscillates up and down on a polypropylene member 17 flexibly attached to a polypropylene base 11 through thin section 24. Attached to the bottom of the core is the moving one 37 of a pair of phosphorbronze contact-carrying strips which co-operates with the fixed strip 41 to make-and-break the coil circuit as the core oscillates. At its upper extremity the core strikes a U-shaped soft iron frame, best seen in Fig. 3 (not shown), which is fixed to the base 11, and which completes the magnetic circuit of the coil. A cover 47 having projection 51 bearing on frame 28 may act as a diaphragm to broadcast the impulses of the core 25 striking frame 28. The device may also be operated by supplying alternating current directly to the terminals of the coil 23.</p> |
