GB359510A - - Google Patents

Abstract

359,510. Sound-reproducing apparatus ; associated working with kinematographs. FRIESS, H., 232, Friedrichstrasse, Berlin. June 11, 1930, No. 17902. Convention date, July 3, 1929. [Class 40 (ii).] Relates to sound - reproducing installations, particularly for working in association with kinematographs, in which an automatic changeover from one gramophone or the like to another is effected. According to the invention, a device is used for bringing about the transition, comprising a potentiometer resistance m arranged in circular formation and coacting with a contact arm m which is adapted to rotate in one direction only. Two terminals r, s of the resistance are connected respectively to one pole of one or other of the gramophone pick-ups u, k, the other poles of the pick-ups being connected together and to the contact arm n. In the arrangement shown, the arm n is carried by one part 1 of an electromagnetic clutch, the other member of which, p, is mounted on a shaft t driving both gramophones. When no current is flowing through the magnet p, the arm n rests on one of the points r, s, and only one pick-up is in action, operating a loud-speaker 10 through an amplifier 9 connected to the potentiometer. As soon as a contact o on the film z closes the circuit of a relay v, the latter completes a circuit from a battery 8 through the magnet p, and the member 1 bearing the arm n is raised and rotated by the shaft t. The circuit of the magnet p is broken as soon as the arm has made half a revolution, by which movement a change-over from one pick-up to the other is effected. The breaking of the circuit, which is brought about by one or other of two arms 2 projecting from the member 1 and operating a switch 6, causes the stoppage of the arm n. A further half-revolution of the arm occurs when the relay circuit is closed by the next film contact, the pick-ups being thus alternately put into operation. The invention is applicable to soundreproducing systems employing film records. The Specification as open to inspection under Sect. 91 (3) (a), describes also the use for effecting a gradual transition from one sound-reproducer to another, of a potentiometer having a sliding contact which is movable by hand over a straight resistance. It also refers to the provision, in the arrangement shown in the Figure, of means for raising and positioning the pick-ups automatically. This subject-matter does not appear in the Specification as accepted.