Technologies
Vacuum Tube
Also Known As Audion
Broadcast
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Lee de Forest's 1907 Audion, the first triode vacuum tube, added a third electrode to the two-electrode diode valve so a weak signal could control and amplify a much larger current. It was the first practical electronic amplifier, and its descendants made long-distance telephony, public address systems and, above all, radio transmission and reception dramatically more powerful and reliable, underpinning broadcast electronics until the transistor began replacing it from the 1950s onward. De Forest himself did not fully understand why the tube amplified; see the open question below.
Facts
Introduced Year OriginPatented by Lee de Forest in the United States as the Audion, the first triode. 1 Cross-Tradition Connections
Associated With
The transistor superseded the vacuum tube in broadcast electronics from the 1950s onward; the two entries are the before and after of the same amplification job.
Developed By
De Forest added a third, grid electrode to Fleming's two-element vacuum tube, creating the three-element Audion triode capable of amplification (US patents 841,387 and 879,532, filed 1906-1907).
In Medium
Sources
1. Wikipedia
Wikimedia FoundationTriodes sectionQuote, Triodes section
Being essentially the first electronic amplifier, such tubes were instrumental in long-distance telephony (such as the first coast-to-coast telephone line in the US) and public address systems, and introduced a far superior and versatile technology for use in radio transmitters and receivers.
1. Wikipedia
Wikimedia FoundationDeveloped By: Lee de Forest, Lee de Forest, Audion inventionView the Source Open Questions (1 open question)
Who actually deserves credit for the vacuum tube's amplification mechanism: Lee de Forest or Edwin Armstrong?
De Forest patented the Audion triode in 1907 but, by most engineering historians' account, did not understand why it amplified a signal. Edwin Armstrong worked out the regenerative feedback mechanism that explained and dramatically improved that amplification around 1912-1913. De Forest then filed competing patent applications claiming he had found regeneration first, based on a 1912 notebook entry, and the priority fight over who actually understood the mechanism reached the US Supreme Court in 1934, which ruled for de Forest on narrow patent grounds even though most engineers and historians credit Armstrong's account of how and why the tube amplifies.
What would resolve this The dispute is over documentary interpretation of surviving notebooks and patent filings rather than new data; a historian's definitive reassessment of the 1912 de Forest notebook entry against Armstrong's own dated laboratory notes would be the closest thing to resolution the field could produce.
History of Technology, Electrical Engineering HistoryWikipedia
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