The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 25
10 The Telephone System of the British Post Office, CHAPTER III. Early Transmitteks. In the Bell telephone the energy of the voice is used to produce thedistant effect, therefore the effects produced cannot be as strong asthe original ones. In order to increase the effects, Edison in 1877invented… … Figure 4. of carbon so arranged that sonorous vibrations will cause varyingdegrees of pressure upon it. The electrical resistance of carbon decreasesunder pressure, and upon this fact it was thought that the action of theinstrument depended. A ferrotype diaphragm DDi is used to receive thesonorous…
Telephone · Postal service
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