Tubes, Discrete Solid State Devices, and Integrated Circuits

In 1883, Edison discovered that electrons flowed in an evacuated lamp bulb from a heated filament to a separate electrode (the Edison effect). Fleming, making use of this principle, invented the Fleming valve in 1905, but when DeForest, in 1907, inserted the grid, he opened the door to electronic amplification with the audion. The millions of vacuum tubes are an outgrowth of the principles set forth by these men.1