An improved apparatus for the production of alternating currents for driving synchronous motors, more particularly for use in connection with picture transmission, television and talking films

摘要

336,868. Telehor Akt.-Ges. Dec. 13, 1928, [Convention date]. Commutator switching-arrangements. - A synchronous motor a for television &c. systems is supplied from a direct-current source b, c through a transformer h and a commutator d which is rotated' by a smaller synchronous motor, such as a phonicwheel e controlled by a tuning-fork or thermionic valve generator.