File:Poulsen's first arc converter.jpg
Poulsen's_first_arc_converter.jpg (530 × 587 pixels, file size: 42 KB, MIME type: image/jpeg)
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Summary
editDescriptionPoulsen's first arc converter.jpg |
English: Prototype arc converter (Poulsen arc) radio transmitter, built by Danish electrical engineer Valdemar Poulsen in 1903. One of the first continuous wave radio transmitters, it was used in the first AM broadcasting stations until the early 1920s, when it was superseded by vacuum tube transmitters. It consists of a DC electric arc in a chamber filled with either hydrogen or other hydrocarbon gas (center) between the poles of an electromagnet (horizontal cylinders front and back). The anode (right) is water-cooled, the cathode is made of carbon and is rotated continuously (mechanism, rear). The arc is connected to a series resonant circuit (not shown) consisting of a capacitor and inductor, which in turn is connected to a wire antenna. The negative resistance of the arc cancels the positive resistance inherent in the resonant circuit, exciting continuous sinusoidal oscillating currents in the resonant circuit, which are radiated by the antenna as radio waves. The arc oscillator was actually invented by Elihu Thomson in 1892, but the frequency of his device was limited to about 10 kHz. By operating it in a hydrogen atmosphere with a cooled anode, Poulsen was able to raise the frequency into the longwave radio range so it could be used for a radio transmitter. |
Date | |
Source | Retrieved September 22, 2013 from http://www.earlyradiohistory.us/1904pou.htm. Originally published in V. Poulsen, "System for producing continuous electric oscillations" in Transactions of the International Electrical Congress, St. Louis, 1904, Vol. 2, Section C: Electrochemistry, J. B. Lyon Co., 1905, fig.7, facing p. 970 on Google Books |
Author | Valdemar Poulsen |
Permission (Reusing this file) |
Poulsen died in 1942, more than 70 years ago |
Licensing
editPublic domainPublic domainfalsefalse |
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This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or fewer. 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. |
This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights. |
https://creativecommons.org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse
Annotations InfoField | This image is annotated: View the annotations at Commons |
Arc chamber containing hydrogen gas
Electromagnet
Water-cooled copper anode
Worm gear to rotate carbon cathode
Gas supply pipe
Rack and pinion to move anode forward
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