An elementary book on electricity and magnetism and their applications (1919)
Jackson, Dugald C. (Dugald Caleb), 1865-1951, Jackson, John Price, b. 1868, Black, Newton Henry, b. 1874 · New York, The Macmillian Co · leaf 594
rlier and the simpler forms of telephone switch-boards still used for small exchanges, the subscribers wireson entering the exchange are each connected to a switchboardcircuit which contains a spring jack and an electromagnet,which controls a drop or shutter. The circuit terminates at aground… … Plate carryingSubscriber». Number Fig. 383. — Electromagnet and shutter fortelephone switchboard. is illustrated in figure 383. The armature A of the electromag-net M has a hook D, which ordinarily supports the shutteror drop P, which ishinged at the bottomin a vertical position.When the…
Electricity · Magnetism
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