Editing Audion (section)

== Applications and use ==
De Forest continued  to manufacture and supply Audions to the US Navy up until the early 1920s, for maintenance of existing equipment, but elsewhere they were regarded as well and truly obsolete by then. It was the vacuum [[triode]] that made practical radio broadcasts a reality.

Prior to the introduction of the Audion, radio receivers had used a variety of [[detector (radio)|detector]]s including [[coherer]]s, [[barretter detector|barretter]]s, and [[crystal detector]]s.  The most popular crystal detector consisted of a small piece of [[galena]] crystal probed by a fine wire commonly referred to as a "[[cat's-whisker detector]]". They were very unreliable, requiring frequent adjustment of the cat's whisker and offered no amplification. Such systems usually required the user to listen to the signal through headphones, sometimes at very low volume, as the only energy available to operate the headphones was that picked up by the antenna. For long distance communication huge antennas were normally required, and enormous amounts of electrical power had to be fed into the transmitter.

The Audion was a considerable improvement on this, but the original devices could not provide any subsequent amplification to what was produced in the signal detection process. The later vacuum triodes allowed the signal to be amplified to any desired level, typically by feeding the amplified output of one triode into the grid of the next, eventually providing more than enough power to drive a full-sized speaker. Apart from this, they were able to amplify the incoming radio signals prior to the detection process, making it work much more efficiently.

Vacuum tubes could also be used to make superior [[radio transmitter]]s. The combination of much more efficient transmitters and much more sensitive receivers revolutionized radio communication during [[World War I]].

By the late 1920s such "tube radios" began to become a fixture of most [[Western world]] households, and remained so until long after the introduction of [[transistor]] radios in the mid-1950s.

In modern [[electronics]], the [[vacuum tube]] has been largely superseded by [[solid state (electronics)|solid state]] devices such as the [[transistor]], invented in 1947 and implemented in [[integrated circuit]]s in 1959, although vacuum tubes remain to this day in such applications as high-powered transmitters, guitar amplifiers and some high fidelity audio equipment.
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'''Application images'''
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[[Image:General electric pliotron pp schenectady 3.jpg|thumb|upright|General Electric Company Pliotron]]
Image:First vacuum tube AM radio transmitter.jpg|The first Audion AM [[radio transmitter]], built by [[Lee de Forest]] and announced April, 1914
Image:De Forest Audion AM radio transmitters.jpg|Some of the earliest Audion [[AM radio]] transmitters, built by de Forest around 1916.  The invention of the Audion [[oscillator]] in 1912 made inexpensive sound radio transmission possible, and was responsible for the advent of [[radio broadcasting]] around 1920.
Image:Audion vacuum tube advertisement.png|Audion advertisement, ''Electrical Experimenter'' magazine, 1916
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