Electrical Engineering ⇒ Topic : Triode

TRIODE

Lee De-Forest made the improvements in the performance of diode in 1907. He introduced a third electrode called the control grid (or only grid) between the cathode and plate of a diode. The grid is placed nearer to the cathode than the plate. So the tube contains three elements namely cathode, grid, and plate. That's why it is called triode valve. A triode valve may be directly or indirectly heated as shown in Figures 1 (a) and (b).

When the positive potential is given to grid with respect to filament, it attracts electrons.Most of the electrons pass through the open spaces in the grid and reach the plate easily. So there is increase in current in the plate circuit. If negative potential is given to grid with respect to filament, it repels electrons and the plate current decreases. In this way, grid regulates the flow of electrons in the plate circuit and enables an easy and delicate control over the plate current.

                                                       FIGURE (1) TRIODE