vacuümtube

Vacuümtube, or vacuum tube, is an electronic device that controls electric current by modulating the flow of electrons in a vacuum. It was a fundamental building block in early electronics and was used for amplification, switching, and rectification in radios, televisions, computers, and communications equipment throughout much of the 20th century. The spelling vacuümtube appears in some European languages, where the term may be used interchangeably with vacuum tube.

A typical vacuum tube consists of a sealed envelope made of glass or metal, containing a heated cathode, one or more grids, and a positively charged anode (plate). When the cathode is heated, electrons are emitted into the vacuum by thermionic emission. The control grid(s) regulate the current between cathode and anode, allowing the device to amplify signals or switch currents. Variants include diodes (one grid) and triodes (one control grid), as well as tetrodes and pentodes with additional grids for improved performance. There are also specialized tubes such as beam power tubes and various microwave tubes (magnetrons, klystrons, traveling-wave tubes) for high-frequency applications.

History and development span the invention of the vacuum tube in the early 1900s, beginning with Fleming’s diode in 1904 and the audion/triode improvements by Lee de Forest in 1906. Vacuum tubes enabled reliable long-distance radio, early computers, and many consumer electronics before being largely supplanted by solid-state transistors from the 1950s onward. They remain in use today in certain high-power radio transmitters, military equipment, and some audio and guitar amplifiers where designers seek specific tonal or dynamic characteristics.

In summary, the vacuümtube was a crucial enabling technology of early electronics, whose legacy persists in niche and high-performance applications.