Editing Audion (section)

{{Short description|Electronic detecting or amplifying vacuum tube}}
{{other uses}}
[[Image:Triode tube 1906.jpg|thumb|[[Triode]] Audion [[vacuum tube]] from 1908. The [[Hot_cathode#Cathode_heater|filament]] (which was also the cathode) was at the lower left inside the tube, but has burned out and is no longer present. The filament's connecting and supporting wires are visible. The plate is at the middle top, and the grid is the serpentine electrode below it. The plate and grid connections leave the tube at the right.]]

The '''Audion''' was an electronic detecting or amplifying [[vacuum tube]]<ref name="Okamura" /> invented by American electrical engineer [[Lee de Forest]] as a [[diode]] in 1906.<ref name="Patent">De Forest patented a number of variations of his detector tubes starting in 1906. The patent that most clearly covers the Audion is {{US patent|879532}}, ''[https://patents.google.com/patent/US879532 Space Telegraphy]'', filed January 29, 1907, issued February 18, 1908</ref><ref name="De Forest">{{cite journal
  | last = de Forest
  | first = Lee
  | title = The Audion; A New Receiver for Wireless Telegraphy
  | journal = Trans. AIEE
  | volume = 25
  | pages = 735–763
  | publisher = American Institute of Electrical and Electronics Engineers
  | date = January 1906
  | url = https://babel.hathitrust.org/cgi/pt?id=uiug.30112089533605&view=1up&seq=356
  | doi = 10.1109/t-aiee.1906.4764762
  | access-date = March 30, 2021| url-access = subscription
  }} The link is to a reprint of the paper in the ''Scientific American Supplement'', Nos. 1665 and 1666, November 30, 1907 and December 7, 1907, p.348-350 and 354-356.</ref><ref name="Godfrey">{{cite encyclopedia
  | last = Godfrey
  | first = Donald G.
  | title = Audion
  | encyclopedia = Historical Dictionary of American Radio
  | pages = 28
  | publisher = Greenwood Publishing Group
  | year = 1998
  | isbn = 9780313296369
 | url = https://books.google.com/books?id=4l_2kkv5aeMC&q=%22Audion&pg=PA28
  | access-date = January 7, 2013}}</ref><ref name="IA-SA-reprint">{{cite journal |last1=de Forest |first1=Lee |title=The Audion - A new receiver for wireless telegraphy |journal=Scientific American |date=30 Nov 1907 |volume=64 |issue=1665 |pages=348–352 |url=https://archive.org/details/sim_scientific-american-supplement_1907-11-30_64_1665/page/348/mode/1up |access-date=21 October 2023}} Non-paywalled reprint of the DeForest presentation at the October 26, 1906 New York meeting of the AIEE. Text version available at the [https://www.earlyradiohistory.us/1907aud.htm Early Radio History] site.</ref> Improved, it was patented as the first [[triode]] in 1908,<ref name="Okamura">{{cite book  
  | last = Okamura
  | first = Sōgo
  | title = History of Electron Tubes
  | publisher = IOS Press
  | year = 1994
  | pages = 17–22
  | url = https://books.google.com/books?id=VHFyngmO95YC&q=Audion+triode&pg=PA21
  | isbn = 9051991452}}</ref><ref name="Newnes">{{cite encyclopedia
  | last = Amos
  | first = S. W.
  | title = Triode
  | encyclopedia = Newnes Dictionary of Electronics, 4th Ed.
  | pages = 331
  | publisher = Newnes
  | year = 2002
  | isbn = 9780080524054
 | url = https://books.google.com/books?id=lROa-MpIrucC&q=triode&pg=PA331
  | access-date = January 7, 2013}}</ref><ref name="Hijiya">{{cite book  
  | last = Hijiya
  | first = James A.
  | title = Lee de Forest
  | publisher = Lehigh University Press
  | year = 1992
  | pages = 77
  | url = https://books.google.com/books?id=JYylHhmoNZ4C&pg=PA77
  | isbn = 0934223238}}</ref><ref name="Lee">{{cite book  
  | last = Lee
  | first = Thomas H.
  | title = Planar Microwave Engineering: A Practical Guide to Theory, Measurement, and Circuits
  | publisher = Cambridge University Press
  | year = 2004
  | pages = 13–14
  | url = https://books.google.com/books?id=uoj3IWFxbVYC&pg=PA13
  | isbn = 0521835267}}</ref><ref name="Hempstead">{{cite book  
  | last1 = Hempstead
  | first1 = Colin
  | first2 = William E. |last2=Worthington
  | title = Encyclopedia of 20th-Century Technology, Vol. 2
  | publisher = Taylor & Francis
  | year = 2005
  | pages = 643
  | url = https://books.google.com/books?id=0wkIlnNjDWcC&pg=PA648
  | isbn = 1579584640}}</ref> consisting of an evacuated [[glass tube]] containing three [[electrode]]s: a heated [[Electrical filament|filament]] (the cathode, made out of [[tantalum]]), a [[control grid|grid]], and a [[Plate electrode|plate]] (the anode).<ref name="Godfrey" /> It is important in the [[history of technology]] because it was the first widely used electronic device that could [[amplifier|amplify]].<ref name="Godfrey" /> A low power signal at the grid could control much more power in the plate circuit.

Audions had more [[Gas-filled tube|residual gas]] than later vacuum tubes; the residual gas limited the [[dynamic range]] and gave the Audion non-linear characteristics and erratic performance.<ref name="Okamura" /><ref name="Lee" /> Originally developed as a radio receiver [[detector (radio)|detector]]<ref name="De Forest" /> by adding a grid electrode to the [[Fleming valve]], it found little use until its amplifying ability was recognized around 1912 by several researchers,<ref name="Lee" /><ref name="Nebeker">{{cite book
  | last = Nebeker
  | first = Frederik
  | title = Dawn of the Electronic Age: Electrical Technologies in the Shaping of the Modern World, 1914 to 1945
  | publisher = John Wiley & Sons
  | year = 2009
  | pages = 14–15
  | url = https://books.google.com/books?id=xwmH6-q5O5AC&q=nebeker+audion+%22De+forest&pg=PA14
  | isbn = 978-0470409749}}</ref> who used it to build the first amplifying [[radio receiver]]s and [[electronic oscillator]]s.<ref name="Hempstead" /><ref name="Armstrong1915">{{cite journal
|last=Armstrong
|first=E. H.
|author-link=Edwin Howard Armstrong
|pages=215–247
|title=Some Recent Developments in the Audion Receiver
|journal=Proceedings of the IRE
|volume=3
|number=9
|date=September 1915
|url=https://books.google.com/books?id=AF0AAAAAMAAJ&pg=PA215
|doi=10.1109/jrproc.1915.216677|s2cid=2116636
|url-access=subscription
}}.  Republished as {{cite journal
|last=Armstrong
|first=E. H.
|author-link=Edwin Howard Armstrong
|title=Some Recent Developments in the Audion Receiver
|journal=Proceedings of the IEEE
|volume=85
|number=4
|date=April 1997
|url=http://www.ieee.org/documents/00573757.pdf
|pages=685–697
|doi=10.1109/jproc.1997.573757}}</ref>  The many practical applications for amplification motivated its rapid development, and the original Audion was superseded within a few years by improved versions with a higher vacuum.<ref name="Lee" /><ref name="Nebeker" />