The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 121
Fig. 88.—Scale 1 … Fig. 89.—Scale £ currents, so causing the n pole of the magnet to vibrate be-tween the two. Whilst this ringer is generally satisfactory,it has the disadvantage that the magnet armature is liableto lose its strength. For this reason, Messrs Ericsson haverecently adopted a ringer having thesame…
Telephone
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