The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 578
ansof the instrument shown in Fig. 496. It consists of aninduction coil fitted with a pivoted armature, to whichan arm with ratchet-tooth lever is attached. The ratchetwheel, against the rim of which the spring presses, is so con-structed that every alternate tooth is an insulating one. When it is… … ratchet moves the wheel one tooth round, so that the springmakes a conducting contact which completes the primarycircuit in which is local battery and transmitter. When it is desired to disconnect, a strong current is againsent through the line (taking care that it is in such a directionas to…
Telephone
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