“Unlocking the Future: How a Simple Discovery Revolutionized Technology and Changed Our Lives Forever”
Edison ultimately patented the device for its potential use as a sort of voltage regulator, but seemingly did not understand the implications beyond that. Importantly, he did show it off at the International Electrical Exposition in Philadelphia in 1884, with one William Preece bringing several of these bulbs back to England and coining the term “Edison Effect,” also now known as “thermionic emission,” in a paper he published the following year on the phenomenon. And, of course, as noted, a couple decades later Fleming was inspired by all this and ultimately did his thing, as did others like Lee de Forest in the United States and the electronics age was born.
Vacuum tubes came in two basic varieties, which allowed electricity to be controlled in particular ways. The diode or thermionic valve, invented by Fleming in 1904, consisted of an evacuated glass bulb containing two basic components: a fine metal wire anode and a plate-shaped cathode. When current was run through the anode, as alluded to in the Edison test, the filament heated up red-hot and began giving off electrons via a process called thermionic emission. These electrons were then caught by the cathode, allowing the current to pass through the diode. If, however, the current was reversed, the lack of a filament on the cathode prevented it from heating up and emitting electrons – meaning the current could not flow in that direction. Diodes thus functioned like one-way valves – hence their alternative name – and were widely used as rectifiers for detecting radio signals, replacing the temperamental crystal detectors previously used in commercial radio sets.
