The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 91
hown in section in Fig. 56.The coil is fixed in a central blockof ebonite, and side cheeks ofebonite screwed on to this blockserve to clamp two soft-iron dia-phragms very close to the twoends of the core. On the outsideof these cheeks the two magnetpoles are fixed in contact with twosoft-iron… … icale | RECEIVERS IN GENERAL USE 69 and the sides of the bobbin by small holes, as shown. Theends of the coils are connected to terminals, a and b. The diaphragm and coil being in a strong magnetic field,the core of the coil is strongly magnetised by induction. Theinstrument is efficient, but is…
Telephone
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