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 36
icating Switching Device.—For small sys-tems such as those of hotels, the intercommunicating switchingdevice is often combined with the telephone set; but when thereare a large number of subscribers, an exchange or central stationis necessary, where the wires connecting the various subscribers… … Fi.G 2,934.—Circuit diagram of the original metallic circuit magneto switchboard operatorsset. CD represent subscribers drops and jacks, ED the clearing out drop, RK a ringingkey and LK a listening key; CP is the calling plug, C the operators induction coil, Tthe transmitter, B the battery, R the…
Electrical engineering
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