Vacuum Tubes





The vacuum tube was invented by Lee De Forest in 1907 and called Audion, first amplifying vacuum tube or triode of the world. Lee De Forest was born in Council Bluffs, Iowa (USA) ion August 26, 1873. He had obtained Ph.D in Physics in 1899 on the subject “Reflection of Hertzian waves from the Ends of Parallel Wire“.

He had joined Western Electric Company in Chicago in dynamo department. He is a formally educated scientist and regarded as “Father of Radio” for contribution in radio electronics.

The Vacuum tube was used in First generation computer. It is a more power consuming and delicate valve because more electric power is needed to head filament. The diode was invented by john Ambrose Fleming in 1904. The diode has cathode and anode filled in vacuum tube. The triode is a modified version of diode valve.

Triode is an evacuated glass tube with three electrodes: anode, cathode, and grid.The more power is needed to heat cathode filament, when it is heated red hot, electrons are emitted and travel towards plate (anode). The grid is applied to control current.

Vacuum Tubes

Vacuum Tube


The main application of a triode is that it raises the strength of a weak signal and thus acts as an amplifier. The weak signal is applied in the grid circuit and amplified output is taken from the plate circuit. So, it is designed to amplify weak radio signal.



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