GB313143A - Improvements in and relating to the generation of electric oscillations - Google Patents

Abstract

313,143. Compagnie des Lampes. June 8, 1928, [Convention date]. Electrically - vibrated instruments. -Relates to means for obtaining pulsating currents of controllable frequency from a source of steady D.C. or A.O. for use, for example, in producing musical sounds. According to one arrangement, Fig. 2, a telephone or loud speaker T is connected in the circuit of a condenser C shunted across a discharge device L, the condenser being charged through a variable resistance R from supply terminals A, B and discharging periodically when its voltage reaches the breakdown voltage of the device L. The frequency of discharge is varied by variation of the capacity of the condenser C, and the magnitude of the resistance R. Further control enabling amplitude to be varied independently of frequency is provided by a variable condenser C1 shunted across the resistance R, and by an inductance S. In alternative arrangement, the telephone or loud speaker T is connected in series with the device L as shown in Fig. 4. In this arrangement a variable resistance Q and shunt condenser are connected across the device T for varying the amplitude of the current passing through the sound-producing instrument. Other arrangements are described in which a plurality of circuits for producing pulsating currents of different frequencies are connected to one or more sound-producing instruments. The arrangements described are also stated to be applicable to operating tuning forks.