File:Design and performance of magnets in the automatic telephone (1912) (14775942853).jpg

Identifier: designperformanc00hays (find matches)
Title: Design and performance of magnets in the automatic telephone
Year: 1912 (1910s)
Authors: Hays, Don Llewelyn Thvedt, Christian Bernhard
Subjects: Electromagnets Electromagnets Telephone, Automatic Theses
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Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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oaies.Air gap z« was adjusted to any deaired value by means of the thumbaorew T which engaged nut N in the lower part of the frame. Aa outlined in Figure 3 and aa just deaoribed, thia devioe per. f (11) mitted the measurement of the lifting power of the magnets by themeasurement of the torque exerted upon the lever Ur (Figs. 3 and ;)By placing weights upon the pan of suoh amount as to enable the mag-nets to barely lift the armature with its load, and then weighingthe total (armature and pan together with the weights upon the pan)accurately upon the scales, the lift of the magnets under variousconditions was readily determined* Figure k shows three views of a standard vertical magnet arma-ture. Suoh armatures are made of No.9 (Brown and Sharpe)Norway ironannealed, having a thickness of .Ilk- inoh. The armature, as isshown to a certain extent in Figure 3, moves about a round steelpin 0 as a fuiorum. This pin fits closely into drilled holes inwings of the armature as shown in Figure 4b.
Text Appearing After Image:
Figure 4. (12) First among the testa made was that to determine the liftingpower of the magnets for various values of ourrent. The resultsof this test are shown in tabulated form on page and graphicallyin the form of a ourve on page 16 (See Graph No.l) Under usual conditions of operation of automatio telephoneswitoh magnets, the ourrent is limited by the voltage Employed.Thisis neooessary owing to the magnets being wound with suoh size wireas to oonveniently oarry a oertain maximum ourrent for a time with-out overheating and possibly destroying the magnets. Tn obtainingdata on page l5the magnet ooils were found to heat very rapidlywhen the higher values of ourrent were used. Graph No.l shows thatmore ourrent is required proportionally to the weight lifted forsmaller than for larger weights. This is to be expeoted when it isremembered that the inertia of the weights, pan and armature mustbe overcome. A second cause for a proportionally greater ourrentto lift the smaller weights upon th

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