Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book (1903)
Swoope, Coates Walton. [from old catalog] · New York, D. Van Nostrand company · leaf 346
itter is practically analternating current dynamo,driven by the energy of thehuman voice, while the re-ceiver is a motor driven bythe current from the gen-erator. 311. The MicrophonePrinciple.—A microphoneis a device for renderingfaint or distant sounds dis-tinctly audible, and is used in many… … Fig. 296.—Apparatus to Illustrate the Principle of the Microphone. 328 PRACTICAL ELECTRICITY. are two carbon buttons one of which is fastened to a thinpine wood sounding board and the other to a brass spring, S>which causes B to touch A. The buttons are connected incircuit with a telephone and…
Electricity · Magnetism
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![An illustration from The Telegrapher [microform] (1864)](https://img.insideoutlibrary.com/img/200/ia-telegrapher05nati-320-204.webp)
