The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 81
is shown in Fig. 43. Adiaphragm of mica, m, is mounted over an opening in a box,as shown, and a strip of platinum, c (only the end of whichis shown), is attached to its centre, and projects at right anglesfrom it. The end of c lies flat on the surface of a chalkcylinder, a, which is moistened with… … Fig. 42 cylinder by the handle, w, so that the top moves away fromthe mica disc, the friction (which can be regulated by thescrew e) will cause the centre of the disc to be pulled inward.On a current passing, the friction at the contact will be reducedin proportion to the strength of the current,…
Telephone
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