An electronic device that controls the flow of electrons in a vacuum. It is used as a switch, amplifier or display screen (CRT). Used as on/off switches, vacuum tubes allowed the first computers to perform digital computations. Although tubes made a comeback in high-end stereo components, they have long since been abandoned for TVs and computer monitors. See vacuum tube types, audiophile, tube amplifier and Vintage Radio Museum.
Early Vacuum Tube
Early vacuum tubes were used to amplify signals for radio and other audio devices. This one was made in 1915. Tubes were not used as switches in calculating machines until 1939. (Image courtesy of AT&T.)
Tubes in the 21st Century
Many audiophiles claim vacuum tubes amplify music better than transistors. These high-end Model One amplifiers (collectively weighing 212 pounds) were designed by legendary audio engineer Mark Levinson.
Vacuum tubes have come in myriad shapes and sizes over the years, and the Vintage Radio and Communications Museum has one of the finest collections. (Images courtesy of Vintage Radio and Communications Museum of Connecticut, www.vrcmct.org)