The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 138
Part of the ringing battery SUB-STATION INSTRUMENT CONNECTIONS 115 (which for lines under 1J miles in length need not exceed fourcells) is used for the microphone battery. As one end of theringing battery is joined to earth or to return wire it is necessaryto insulate the primary circuit from… … Fig. 119 purpose is, therefore, provided on an insulated conductorattached to or moved by the switch-hook when a hand-micro-telephone is not used. To close the battery circuit for ringingthe distant station a push button, or lever key, is used,connected to one of the line wires, and provided with a…
Telephone
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