This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 Excerpt: ... a steel needle N; S is a brass spring by which the pressure of the contact can be regulated. The adjustment of the spring is regulated by means of the disc D. Professor Hughes used the microphone with or without a battery in the local circuit; and when the battery was omitted, he attributed the sound in the telephone ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 Excerpt: ... a steel needle N; S is a brass spring by which the pressure of the contact can be regulated. The adjustment of the spring is regulated by means of the disc D. Professor Hughes used the microphone with or without a battery in the local circuit; and when the battery was omitted, he attributed the sound in the telephone to the thermoeleetromotive force developed at the carbon-steel junction. The detector was more sensitive with a battery in the local circuit than without it. Various modifications of this microphonic detector of Hughes have been employed in practical wireless telegraphy. One modification, which had a considerable application a few years ago, Fig. 110. Hughes's microphonic steel-carbon detector. Fig. 111. Steel-carbon detector. Fig. 112. Detector of carbon granule between metallic plugs. is obtained by placing a steel needle across two blocks of carbon, as shown in Fig. 111. Another is made by placing a granule of carbon between metallic plugs in a tube, as shown in Fig. 112. The microphone is more sensitive than the filings coherers. It is, however, somewhat troublesome on account of sensitiveness to mechanical vibrations and on account of liability to cohere under strong signals, and it is surpassed in sensitiveness to electric 1 Fahie, History of Wireless Telegraphy, 1902, Dodd, Mead & Co. waves by the crystal detectors, in which the carbon of Hughes's microphone is replaced by certain crystalline mineral substances. Dunwoody's Carborundum Detector.--In 1906 General H. H. C. Dunwoody 1 of the United States Army (retired) discovered that a fragment of carborundum, when provided with suitable electrodes for connecting it into the circuit, will act as a receiver for electric waves. Carborundum is a carbide of silicon, manufactured in the el...
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
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Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.