Method and device for transforming waves of audible, ultra-audible or infra-audible frequencies into modulations of an electric current, and conversely

摘要

659,796. Microphones ; loud - speakers. KLEIN, S., and COMPTOIR DES CENDRES ET METAUX PRECIEUX. March 1, 1945, No. 5124. [Class 40 (iv)] [Also in Group XL (a)] Apparatus for transforming acoustic vibrations into modulations of an electric current or vice versa comprises an electrode 1 emitting positive ions and a co-operating electrode 4, the acoustic vibrations passing through the space between the electrodes and acting on, or being acted on by, the stream of free ions. Electrode 1 may be provided with a heater 3 and the terminals 6 and 7 to be impressed with the electric oscillations are connected across a resistance 6 in series with electrodes 1 and 4. Electrode 4 may be coated with insulating enamel in which case the electrodes 1 and 4 mainly function together as a capacity. The electrode 1 may be a thermionic emitter of positive ions as described in Specification 657,032, [Group XL (a)].