GB241339A - Improvements in or relating to vibratory signalling devices - Google Patents

Abstract

241,339. Walker, W. L. Aug. 25, 1924. Plate and tube vibrators.-A soundproducing device comprises a thin resonant shell or casing containing within it a vibratory member which is situated close to the walls of the casing and communicates its vibrations thereto, the casing also containing means for setting the vibratory member into vibration. In the construction shown, a rectangular tubular brass casing 11 contains flat vibratory members 10 - - 13 clamped so as to lie parallel to and at a short distance from the walls of the casing. The members 10 - - 13 are set into vibration by electromagnets 5, 6 supplied with alternating current or pulsating direct current through leads 28 passing through watertight glands 31. The vibrations of the members 10 - - 13 are communicated to the casing by their free ends striking anvils 22. In modifications, the casing and vibratory members are cylindrical, the latter being formed either as a complete cylinder or as two semicylinders. The vibrations may be communicated to the casing through the intervening narrow air space instead of by direct blows. The device is particularly adapted for subaqueous use and a number may be arranged at intervals along a submerged cable to mark out a navigable course, the magnets being connected in series or parallel. By varying the length &c. of the casing and vibrators the device may be timed as desired and the electrical circuit may be similarly tuned. Preferably, in the latter case, the magnet coils are connected in parallel to earth by connecting one end of each coil to the casing.