Humanities › History & Culture The History of Vacuum Tubes and Their Uses Share Flipboard Email Print Bettmann/Getty Images History & Culture Inventions Famous Inventions Famous Inventors Patents & Trademarks Invention Timelines Computers & The Internet American History African American History African History Ancient History and Culture Asian History European History Genealogy Latin American History Medieval & Renaissance History Military History The 20th Century Women's History View More By Mary Bellis Inventions Expert Mary Bellis covered inventions and inventors for ThoughtCo for 18 years. She is known for her independent films and documentaries, including one about Alexander Graham Bell. our editorial process Mary Bellis Updated February 04, 2019 A vacuum tube, also called an electron tube, is a sealed-glass or metal-ceramic enclosure used in electronic circuitry to control the flow of electrons between the metal electrodes sealed inside the tubes. The air inside the tubes is removed by a vacuum. Vacuum tubes are used for amplification of a weak current, rectification of an alternating current to direct current (AC to DC), generation of oscillating radio-frequency (RF) power for radio and radar, and more. According to PV Scientific Instruments, "The earliest forms of such tubes appeared in the late 17th century. However, it was not until the 1850s that sufficient technology existed to produce sophisticated versions of such tubes. This technology included efficient vacuum pumps, advanced glassblowing techniques, and the Ruhmkorff induction coil." Vacuum tubes were used widely in electronics in the early twentieth century, and the cathode-ray tube remained in use for televisions and video monitors before being supplanted by plasma, LCD, and other technologies. Timeline In 1875, American, G.R. Carey invented the phototube.In 1878, Englishman Sir William Crookes invented the 'Crookes tube', an early prototype of the cathode-ray tube.In 1895, German, Wilhelm Roentgen invented an early prototype Xray tube.In 1897, German, Karl Ferdinand Braun invents the cathode ray tube oscilloscope.In 1904, John Ambrose Fleming invented the first practical electron tube called the 'Fleming Valve'. Leming invents the vacuum tube diode.In 1906, Lee de Forest invented the Audion later called the triode, an improvement on the 'Fleming Valve' tube.In 1913, William D. Coolidge invented the 'Coolidge Tube', the first practical Xray tube.In 1920, RCA began the first commercial electron tube manufacturing.In 1921, American Albert Hull invented the magnetron electronic vacuum tube.In 1922, Philo T. Farnsworth develops the first tube scanning system for television.In 1923, Vladimir K Zworykin invented the iconoscope or the cathode-ray tube and the kinescope.In 1926, Hull and Williams co-invented the tetrode electronic vacuum tube.In 1938, Americans Russell and Sigurd Varian co-invented the klystron tube.