Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 150
rst sight, the natural supposition being that the limbs ofthe permanent magnet are of opposite polarity. This ringer is veryefficient, and it is surprising that it should not have remained inservice, perhaps in a somewhat modified form. Besides being de-sirable in point of efficiency, it has the… … FIG. 103.—OLD WILLIAMS-ABBOTT RINGER. only alternating currents, the current consisting of a positive andnegative impulse for every complete revolution of the armature.It is sometimes desirable to make all of the impulses in the samedirection, as in certain classes of party line ringer, and for…
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