Radio receiver crude triode, was invented in 1906 by Lee De Forest as a more sensitive detector for radio receivers, by adding a third electrode to the thermionic diode detector, the Fleming valve. It was not widely used until its amplifying ability was recognized around 1912. The first tube receivers, invented by De Forest and built by hobbyists until the mid 1920s, used a single Audion which functioned as a grid-leak detector which both rectified and amplified the radio signal. There was uncertainty about the operating principle of the Audion until Edwin Armstrong explained both its amplifying and demodulating functions in a
Triode 22.5V if an anode current of I = 2.25mA is chosen. If the input voltage amplitude (at the grid) changes from −1.5V to −0.5V (difference of 1V), the anode current will change from 1.2 to 3.3mA (see image). This will change the resistor voltage drop from 12 to 33V (a difference of 21V). Since the grid voltage changes from −1.5V to −0.5V, and the anode resistor voltage drops from 12 to 33 V, an amplification of the signal resulted. The amplification factor is 21: output voltage amplitude divided by input voltage amplitude. Triode A triode is an electronic amplifying vacuum