Lexikon's History of Computing

Evolution of the Vacuum Tube


Although radio is a very different technology application than digital computing, early advancements in vacuum tube technology, including new vacuum production techniques and tube production methods and facilities, can be attributed largely to the widespread popularity of early radio.

An overview of the history of vacuum tube development must also give credit to those early inventors who sought to improve radio reception techniques.

The following are some highlights of early developments in vacuum tubes.


Geissler Tubes

One of the first to experiment with vacuum tubes was a German scientific instrument manufacturer, Heinrich Geissler (1814-1879). In the mid-1800's, Geissler found that a current passed through an enclosed gas tube, which contained a partial vacuum and one of a series of gases, would produce a brightly colored glow.

Different gases, such as hydrogen, oxygen, and nitrogen, produced different colors. His devices were known as Geissler Tubes.

Crookes Tubes...

In 1878, the Englishman, Sir William Crookes (1832-1919), expanded on Geissler's research and found that an electrically charged cathode in a tube would produce streams of what he called "cathode rays."

Cathode Rays...

In 1895, the French scientist Jean B. Perrin discovered that "cathode rays" were negatively charged particles.

Between 1895 and 1897, British physicist Joseph J. Thompson did further experiments on these emissions and attempted to measure some of the properties of these particles. The negatively charged particles were later named "electrons."

Electrolytic Detector...

In 1901, Reginald A. Fessenden conducted early experiments with voice transmission and invented the "electrolytic detector."

The Fleming Valve...

In 1904, British scientist John A. Fleming developed a vacuum tube that detected radio signals. His device was called the Fleming Valve.

The Audion...

In 1907, American inventor Lee De Forest patented a tube called the Audion, which amplified signals. The Audion was a major breakthrough in the field of radio. Improvements to the Audion were made between 1912 and 1914 by American scientists Irving Langmuir and Harold D. Arnold. Langmuir and Arnold found that the performance of the Audion could be enhanced by increasing the vacuum in the tube. Further advancements in vacuum tube technology were also made during World War II.

Television Tubes...

Crookes' discoveries were greatly expanded upon in the 1920's by Vladimir Zworykin, who is credited with the invention of the cathode ray tube (CRT), the basis for video display monitors and television screens.


See also: (Chronology of Early Television Technology)


Digital Computing...

New developments in vacuum tubes made possible increased reliability and power of radio transmissions, microwave radar and eventually, electronic digital computing. Millions of tubes were made from the 1930's through the 1950's. The vacuum tube was the heart of many electronic devices, including computers, until the late 1950's. In 1947, the transistor was invented and, by the next decade, began to replace tubes in radios, televisions, computers and other electronic devices. Today, many early radio tubes are considered collectible pieces of technology history. A vacuum tube of the type used in many early computers consists of three basic parts: a cathode, a grid and a plate. The vacuum tube was used as an electronic relay device, since it could be used to represent one of two binary states, "0" or "1."


Vacuum Tube Testers

Vacuum Tube Testers became important tools for those working with any vacuum tube based equipment,

whether radios, televisions, computers or other electronic equipment. Here are two examples of tube testing units.

Examples of Vacuum Tubes in Early Computers

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