GB142447A - Improvements in electric musical instruments - Google Patents

Abstract

142,447. Hugoniot, C. E. April 30,1919, [Convention date]. Instruments with sonorous plates.-Relates to instruments in which sounds having any desired tone are produced synthetically by the action of superimposed undulatory electric currents which pass through the receiver of a loud-speaking telephone. Fig. 1 shows a front elevation of an electric generator for producing superimposed currents. Fig. 2 shows a modification, Fig. 4 an appliance for controlling strength and pitch, and Fig. 5 a section of a detail. The rotor of an alternator comprises a Gramme winding composed of a series of elements a - - f, Fig. 1, and the field magnet is made up of groups of electrumagnets A<1> - - A<6>, each group consisting of a different number. The electro-magnets are supplied with continuous current, the excitation of each group is separately adjustable by means of a rheostat, and gruups may be removed, shortcircuited, or set at a slight angle as required. Polar extensions of various shapes or sizes may be used. The current collected at the brushes B<1>, E<2> is taken to a telephone receiver. The strength of sound for a given note may be varied bv a rheostat acting on the field magnet assemblage or by one interpolated between the armature and the telephone receiver. Pitch is varied by altering the speed of the armature. In the modification shown in Fig. 2, the field magnet consists of groups of poles 1 - - 6, and the armature is formed of groups C1 - - C6 of different numbers of winds carried on a rotating disk. The control mechanism, Fig. 4, consists of a paper strip travelling on rolls i, j and marked with lines h corresponding to the music to be played, which is followed with a style l moved by hand, and connected by links m, n to the rheostat o<1>, in series with the motor driving the alternator, and the rheostat o<2> arranged to prevent variation of voltage when the speed of the motor is varied. The style l is constructed with a small rheostat whose resistance varies with the pressure applied by the player, as shown in Fig. 5, the ebony tube p is filled with pieces of graphite &c., and the sliding part is in contact with a spring q. In a modified style, a spring-pressed piston carries a contact which moves over a spirally coiled wire resistance. Two or more alternators may be coupled together and operated from a single style. The pole-pieces employed may be toothed to reproduce the shape of the vibration of a given sound.