GB144182A - Improvements in electrical installations for controlling electric pianos and other apparatus - Google Patents

Abstract

144,182. Audran, C. July 18, 1919, [Convention date]. Sparking; preventing. - A group of electric circuit closing and opening devices, in particular the contacts of an electric piano, is provided with a spark-preventing condenser and a set of electro-magnets the cores of which constitute switch terminals adapted to throw the condenser into whichever circuit is temporarily active. In the arrangement d i a g r a m - matically shown in Fig. 1, a wire from each contact device c, c<1>, c<2> runs round a corresponding electro-magnet d, d', d<2>, which can attract an armature e which constitutes a switch included in circuit with a condenser h. The stationary contact, as shown in Fig. 3, consists of a brass pin j slightly protruding from the surrounding iron, with the object of preventing sticking-on when the magnet is de-energized. The magnet windings form resistances for reducing the voltage of the operating-current.