Page "Triode" Paragraph 6
from
Wikipedia
The directly-heated cathode ( or indirectly by means of a filament ) produces an electron charge by thermionic emission.
Applying a negative DC voltage (" bias ") to the control grid will repel some of the electron stream back towards the cathode, thus isolating the plate from the cathode ; full bias will turn the tube off by blocking all current from the cathode.
As grid bias is increased, more of the electron current is repelled, resulting in a smaller current at the plate.
An AC signal voltage superimposed on the grid will appear as variations in the plate current ; voltage amplification can be obtained by using a suitable value of plate load resistance.
Page 1 of 1.
1.993 seconds.