A dictionary of electrical words, terms and phrases (1898)
Houston, Edwin J. (Edwin James), 1847-1914 · New York, The W. J. Johnston company · leaf 457
Fig. 480. Microphone Relay. A form of microphone relay is shown in Figs.480 and 481. Several minute microphones mounted on the ROM -saisUMiTTER … Fig. 481. Microphone Relay. diaphragm of the telephone whose message is tobe repeated, so vary the resistance of a local bat-tery included in their circuit as to automaticallyrepeat the articulate speech received. The microphones may De connected either in Rel.] 448 [ReL multiple arc or in series,…
Electricity · Electrical engineering
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![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten20unit-151-55.webp)
