File:The practical telephone handbook and guide to the telephonic exchange (1906) (14755791592).jpg

Identifier: practicaltelepho00pool (find matches)
Title: The practical telephone handbook and guide to the telephonic exchange
Year: 1906 (1900s)
Authors: Poole, Joseph
Subjects: Telephone
Publisher: New York, Macmillan Co.
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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e by two screws which Pass through the sleeve and case,the holes being sligl% elongated, so as to allow of adjust-ment. On account oi tne fixing points being near the bellend of the case, the varil:tion of 8aP Wlth temperature is evenless than with the last ty?e- The screws used for clamping Fig. 47.—Scale £ RECEIVERS IN GENERAL USE 65 are, however, somewhat unfavourable to comfortable hand-ling, but this is only a slight drawback to a very efficientinstrument. To prevent the possibility of the tabs of theconnecting cord coming into contact by the turning of thebinding posts, a thick strip of ebonite is fixed between theposts by a central screw. The diaphragm used in this instrument is of tinned iron,about 10 mils thick and 212 inches diameter. The Kellogg Receiver *—This receiver illustrates anothermethod of fixing the magnet, etc., so as to overcome the ex-pansion trouble. As shown in Fig. 48, a screwed block isfixed to the polar end of the magnet, and the inside of the <3«
Text Appearing After Image:
Fig. 48.—Scale £ ebonite case has a screw cut to correspond. The magnet isscrewed in from the mouth of the case, and as the lengthbetween the fixing point and the pole ends is small the differenceof expansion has little effect. This instrument is provided witha small ebonite cap, which screws over the terminals at the end,thus protecting them from damage or interference, and athickening at the end of the cords relieves the connectingstrands from any strain. Somewhat similar caps were usedon some of the earlier English-made receivers, but as theywere large and clumsy, and associated with inefficient in-struments, they became obsolete. The cap is certainly a goodfeature, and it is to be hoped it will come into general use. The Solid Receiver.—This is a form of instrument inwhich the magnet, pole-pieces, and connecting wires are * The Western Electric Co.s C.B. receiver in general use is verysimilar to this. 66 PRACTICAL TELEPHONE HANDBOOK embedded in the ebonite of the case so as t

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