GB157436A - Apparatus for the intensification without distortion of sounds and tones, for the purposes of acoustic kinematography - Google Patents

Abstract

157,436. Massolle, J., Vogt, H., and Engl, J. July 25, 1919, [Convention date]. Thermionic relays.-Relates to sound recording and reproducing apparatus in which a record is photographically produced on a film, the sound being reproduced by apparatus employing photoelectric cells. According to the invention, intensification of the micro-currents involved in the recording and reproduction is effected by amplifying valves which are galvanically coupled without the use of low frequency transformers. In the case of apparatus employing high frequency currents, high frequency transformers free from iron are employed. Fig. 1 shows a recording apparatus comprising a microphone M and three valves R1, R2, R3. Em is a source of potential connected in circuit with the microphone M through a resistance w1. E1, E2, E3 are sources of potential for the anodes a1, a2, a3, and are connected to the cathodes k1, k2, k3 through resistances w2, w3, w4. The grid-cathode paths of the valves are coupled across the resistances w1, w2, w3 through condensers C1, C2, C3. To the anode circuit of the last valve is applied the recording device proper. This system may be used either for low frequency or for high frequency intensification. In the latter case, one of the sources of potential Em or E1 is a high frequency source. Fig. 6 shows a reproducing system employing high frequency intensification. Z is a photo-electric cell having an anode a and cathode k. The first tube R1 has an auxiliary grid gh supplied with high frequency potential from a source H through a transformer t1. Successive tubes are coupled by high frequency transformers t2, t3, t4 without iron cores.