Invention
The tetrode tube was developed by Dr. Walter H. Schottky of Siemens & Halske GmbH in Germany in 1919. Thousands of variations of the tetrode design, as well as its later development the pentode, have been manufactured since then, although vacuum tubes in low-power equipment have been almost totally superseded by solid-state semiconductor devices.
Read more about this topic: Tetrode
Famous quotes containing the word invention:
“Books are fatal: they are the curse of the human race. Nine- tenths of existing books are nonsense, and the clever books are the refutation of that nonsense. The greatest misfortune that ever befell man was the invention of printing.”
—Benjamin Disraeli (1804–1881)
“Retirement requires the invention of a new hedonism, not a return to the hedonism of youth.”
—Mason Cooley (b. 1927)
“The rage for road building is beneficent for America, where vast distance is so main a consideration in our domestic politics and trade, inasmuch as the great political promise of the invention is to hold the Union staunch, whose days already seem numbered by the mere inconvenience of transporting representatives, judges and officers across such tedious distances of land and water.”
—Ralph Waldo Emerson (1803–1882)