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 304
own in fig.3,292. In the vestibule there is adoor opener, which consists essentiallyof a magnet and armature, and fourpush buttons. A battery of threedry cells is located in the basement orcellar. This may be disconnected anda bell ringing transformer substitutedin its place connected as shown in… … *IG. 3,290.—Annunciator circuit for single elevator. ^IG. 3,291.—Annunciator circuit for two passenger elevators, or two freight elevators. Itshould not be used in the case of a passenger and a freight elevator. 2,396 HAWKINS ELECTRICITY
Electrical engineering
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