Hawkins electrical guide ... : questions, answers & illustrations : a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications ; a practical treatise (1914)
Hawkins, N. (Nehemiah), 1833-1928 · New York : T. Audel & Co. · leaf 69
ranted! SOUNDER RELAY … TELEGRAPH KEY Fig. 2,974.—Wiring diagram showing telephone and Morse telegraph circuits connected toa telephone line. In operation by plugging in metal pegs between the brass bars and thediscs, line combinations can be made so that telegraph or telephone communication maybe had over any line. Local…
Electrical engineering
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