Patent GB-190114235-A (GB)
Title: Improvements in or relating to Audible Electric Signalling Devices.
Inventor: BROWN STUART AUGUSTUS
Filed: 1901-07-12
Granted: 1902-01-09
Abstract: 14,235. Brown, S. A., and Points, J. W. July 12. Signals, electric audible.-Relates to apparatus of the kind in which the sound vibrations are produced by the movements of a flexible diaphragm actuated by an electromagnet. In the form shown in Fig. 1, the vibrating diaphragm 10 is mounted on, and insulated from. the tubular stem 7 on the frame 6. the circuit of the operating-electromagnet 19, 20 being made and broken between the contact 16 on the diaphragm and the contact 15 on the insulated plate or diaphragm 13. The circuit is from the terminal 25, through the plate 13. contacts 15, 16, diaphragm 10, electromagnet 19, 20, back armature 17, stem 7, frame 6, and terminal 26. The initial contact is made by pulling a cord attached to the outer end of the lever 30, the arm 31 of which forces the contact 15 against the contact 16, while the lever 30 itself acts on the supporting-stem 36 to raise the resonator or cover 35. The magnetic field is adjustable angularly with respect to the position of the contact 16, which in action tends to establish a node in the vibrating diaphragm, the adjustment thus enabling the tone to be varied. In a modification, the lever 30 is actuated by an electromagnet connected in parallel with the magnet 19, 20. In another modification. the cover 35 is carried by a hoop connected to a vertical stem, and is actuated by a separate lever linked to the lever which closes the contacts 15, 16. The diaphragm and back armature also are connected together and carried by a rectangular frame surrounding the magnet. In another arrangement, the back armature is movable vertically, and acts through a pair of levers to raise the casing. In the form shown in Fig. 4, designed especially for fogsignalling &c., the operative parts are enclosed in a pivoted casing 92, having an opening 93 to which is attached a megaphone 94. When the lever 100 is pulled, the apparatus is turned until the megaphone lies in a horizontal position, and the circuit of the magnet 94<1> is then completed between the contacts 107, 96, the latter contact being carried by the diaphragm 95'. Fig. 7 shows another arrangement with a fixed resonator, and the contacts 125, 126 arranged in a shunt circuit. The diaphragm 122 is raised by the magnet until it connects the contacts 125. 126, and is then released owing to the magnet being short-circuited. Fig. 8 shows a simple form for continuous currents, the circuit being from the terminal 140, electromagnet, back armature, diaphragm 136, contacts 137, 139, and frame 131 to the terminal 141. Another form for variable currents comprises an electromagnet between the poles of which is a post carrying three diaphragms mounted rigidly at their centres in axial alignment. The middle diaphragm carries two stops, which establish nodes when the upper and lower diaphragms come in contact with them. Two other diaphragm arrangements are described. In one, the main diaphragm has two smaller diaphragms at diametrically-opposite points near its periphery ; in the other, the diaphragm is diamagnetic, and is provided with paramagnetic discs adjacent to the poles of the magnet.