First_Audion_amplifier_1914.jpg
Size of this preview:
391 × 599 pixels
.
Other resolutions:
157 × 240 pixels
|
313 × 480 pixels
|
501 × 768 pixels
|
668 × 1,024 pixels
|
1,556 × 2,383 pixels
.
Summary
Description First Audion amplifier 1914.jpg |
English:
One of the first Audion
amplifiers
built by the inventor of the
Audion
vacuum tube,
Lee De Forest
, around 1914. The Audion, the first
triode
, was the first electronic tube that was able to
amplify
. Although invented in 1906, the amplifying ability of the Audion was not recognized until 1911-1912, so this was one of the first amplifiers. It appears in a paper by De Forest demonstrating to his fellow engineers that the Audion was not just a radio detector but also had the ability to amplify a signal. This is a three-stage transformer coupled audio amplifier. The Audion bulbs are visible on the front. Audions were always mounted upside-down, with the fragile filament loop hanging down, to prevent it from sagging when hot and touching the grid. Next to each tube are two rotary switches, one to control the filament current and one the plate voltage. The plate voltage between 15 and 40 volts, had to be carefully controlled. The primitive Audion was not completely evacuated, but had some gas in the tube, so if the plate voltage exceeded about 40 volts the gas would break down and ionize, emitting a "blue glow" discharge; which could damage the tube. The tube had a voltage gain of up to 5, so this amplifier had a maximum gain of about 125.
|
Date | |
Source | Downloaded 03-26-2013 from Lee De Forest The Audion - Detector and Amplifier in Proc. of the Institute of Radio Engineers ( Institute of Radio Engineers, NY) Vol. 2, No. 1, March 1914, p.23, fig. 5 on Google Books |
Author | Lee De Forest |
Licensing
Public domain Public domain false false |
This media file is in the
public domain
in the
United States
. This applies to U.S. works where the copyright has expired, often because its first
publication
occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See
this page
for further explanation.
|
||
This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the
rule of the shorter term
for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See
Wikipedia:Public domain
and
Wikipedia:Copyrights
for more details.
|