A four-element electron tube containing an anode, cathode, control grid, and additional electrode.
An electron tube that has four electrodes (a cathode, anode, and two grids), used to generate, amplify, modulate, or demodulate electrical signals.
A four-element electron tube containing an anode , cathode , control grid , and additional electrode called the screen . They function in the same manner as triode , but are more effective at higher frequencies due to the effect of the screen.
A type of vaccum tube currently used in high-end audio amplifiers. A tetrode is like a triode with the addition of a "screen grid" between the control grid and the plate (anode). The screen grid is an electrostatic shield typically biased with a fixed voltage that isolates the control grid and protects it from voltage potential changes on the plate.Dynatrons are special types of tetrodes that utilize a screen grid voltage higher than the plate voltage. This causes the plate current to decrease as plate voltage increases. This characteristic, known as negative resistance, is useful in oscillator circuits. See triode and diode.