GB129670A - Improvement in Methods and Apparatus for Eliminating Undesired Vibrations of Particular Frequencies. - Google Patents

Abstract

129,670. Fessenden, R. A., and Leslie, F. H. June 8. 1917, [Convention date]. Telephone systems and apparatus. - Undesired vibrations of particular frequency, such as the natural frequency of a diaphragm. are minimized by the use of an element adjusted tc absorb vibratory energy at the particular frequency. The invention is applicable to diaphragms of sound receiving apparatus such as telephones. Electrical and mechanical embodiments are described. As shown in Fig. 3, the invention is applied to an oscillator 22 of the kind described in Specification 18765/13 used in subaqueous signalling or telephony. As manufactured, this oscillator is markedly responsive to two particular frequencies, and the undesirable resonance effect is eliminated by the use of two tuned circuits, one comprising an inductance 23, resistance 24, and capacity 25 adjusted for one frequency and the other comprising an inductance 26, resistance 27, and capacity 28 adjusted for the other frequency. When so shunted and connected with a telephone transmitter 21, the oscillator 22 can be used for transmitting speech through water. Fig. 4 shows a mechanical application to a rotary shaft which vibrates when a particular speed of rotation is reached. A cylinder 45 is mounted so as to be free to oscillate on a piston having apertures 41, 42 and connected to the shaft by a rod 38. The dimensions of the parts are so chosen that when the critical speed at which vibration occurs is reached, the cylinder oscillates, energy being absorbed by the throttling effect of the apertures 41, 42 on the air passing in and out. The rod 38 is connected to the shaft through an eccentric 37 which is stated to minimize lateral movement of the rod due to bending of the shaft. In other applications, the rod 38 is connected to the diaphragm or other vibrating body.