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File:Braun wireless receiving transformer 1905.jpg

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Summary

Description
English: An early resonant transformer invented by Ferdinand Braun used in the coherer radio receivers in wireless telegraphy radio systems made by the Telefunken company in 1903. The antenna is connected to the primary winding (center). The secondary winding inside it is connected to a capacitor to make a tuned circuit, and to the receiver's detector. A sliding contact on the inner winding allows more or fewer turns of the coil into the circuit, tuning the receiver to different stations. The coupling between the two coils can be increased or decreased by sliding the primary up or down on the rails.

Braun is credited with discovering the benefits of inductive coupling in radio transmitters and receivers. He found that "loosely coupled" tuned circuits like this had much narrower bandwidth than single tuned circuits. For these discoveries he shared the 1909 Nobel Prize in physics with Guglielmo Marconi. Information from Sarkar et al (2006) History of Wireless, p. 358
Date
Source Retrieved January 14, 2016 from "Telefunken System of Wireless Telegraphy" in The Electrical Magazine and Engineering Monthly", The Electrical Publishing Co., London, Vol. 5, No. 1, July 29, 1905 p. 96, fig. 4 on Google Books
Author Unknown authorUnknown author

Licensing

Public domain
This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1929.
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Note: This tag should not be used for sound recordings.PD-1923Public domain in the United States//commons.wikimedia.org/wiki/File:Braun_wireless_receiving_transformer_1905.jpg
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This UK artistic or literary work, of which the author is unknown and cannot be ascertained by reasonable enquiry, is in the public domain because it is one of the following:
  • A photograph, which has never previously been made available to the public (e.g. by publication or display at an exhibition) and which was taken more than 70 years ago (before 1 January 1954); or
  • A photograph, which was made available to the public (e.g. by publication or display at an exhibition) more than 70 years ago (before 1 January 1954); or
  • An artistic work other than a photograph (e.g. a painting), or a literary work, which was made available to the public (e.g. by publication or display at an exhibition) more than 70 years ago (before 1 January 1954).

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Captions

Ferdinand Braun's tuning coil

Items portrayed in this file

depicts

inception

29 July 1905Gregorian

media type

image/jpeg

checksum

00c2678b8130d1315e82e2288bfbf85fb1886c77

determination method or standard: SHA-1

data size

14,420 byte

height

345 pixel

width

258 pixel

File history

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Date/TimeThumbnailDimensionsUserComment
current02:50, 5 February 2016Thumbnail for version as of 02:50, 5 February 2016258 × 345 (14 KB)ChetvornoUser created page with UploadWizard

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