This section provides overview, applications, and principles of vacuum tubes. Also, please take a look at the list of 15 vacuum tube manufacturers and their company rankings.
Table of Contents
A vacuum tube is a hollow tube (tube bulb) with a highly vacuumed interior and enclosed electrodes. Electrons can be amplified, detected, rectified, oscillated, and modulated by controlling the electrons with electric and magnetic fields.
Vacuum tubes are also called electron tubes because they apply the action of electrons. Generally, a vacuum tube consists of a container made of glass, metal, or ceramics, inside which multiple electrodes are placed to create a vacuum or low pressure, and a small amount of rare gas or mercury is added.
Depending on the number of electrodes, the tubes are called bi-polar, tri-polar, quadrupolar, or pentode tubes. Furthermore, among 2-pole tubes, those used for rectification are especially called rectifier tubes.
Vacuum tubes have almost completed their role as elements for general purposes (rectification, modulation, detection, amplification, etc.) in general electrical and electronic circuits, and many of them have been replaced by semiconductor elements. They are also manufactured for broadcasting stations and the military. Vacuum tube amplifiers are still preferred for audio amplifiers and guitar amplifiers because of their excellent sound, and large quantities of vacuum tubes are still being produced for these applications.
Magnetrons, a special type of vacuum tube, are still being produced today as a source of powerful microwaves for use in microwave ovens and radar.
Vacuum tubes are also used in other sophisticated and advanced applications, such as X-ray tubes for generating X-rays, photomultiplier tubes (PMTs) for high-sensitivity optical measurements, and night-vision tubes (image intensifiers).
When a material is heated to a high temperature in a vacuum, electrons in the material gain thermal energy and are emitted from the surface of the material. This phenomenon is called thermionic emission, and most vacuum tubes are made using this phenomenon.
In a bipolar vacuum tube, when the filament is heated to a high temperature, thermal electrons are emitted, and when a positive potential is applied to the plate, electrons are attracted to the plate, and an electric current flows. In other words, when an alternating voltage (alternating positive and negative voltage) is applied to the plate, current flows only when the voltage is positive, and no current flows when the voltage is negative. This is called rectification.
In a triode vacuum tube, a grid (wire mesh) is placed between the plate and the filament, and the flow of electrons from the filament to the plate can be controlled by varying the potential of the grid. If the grid potential is made more negative, the number of electrons flowing to the plate can be reduced. And the change in current flowing to the plate will be larger than the change in grid voltage. In other words, if you put a load resistor in the plate circuit and measure its voltage, the voltage change across the load resistor will be greater than the grid voltage change. This is the amplification effect.
There are also quadrupole, pentode, and beam tubes as improved versions of the triode tube.
There are several types of vacuum tubes, each with different properties. Select the one that matches your purpose.
Used in amplifiers that amplify music and instrumental performance signals
Used in transmitters for radio communication and broadcasting and in high-frequency generators for industrial use
CRTs are used in cathode-ray tubes and other electron beam image display devices
Used in devices that generate microwaves, such as radars and microwave ovens
Used in the past for TV cameras, but recently used in nuclear reactor decommissioning work, etc., due to their radiation-resistant characteristics
Used in night vision equipment and goggles
Used in dental and industrial X-ray inspection equipment
*Including some distributors, etc.
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Ranking as of January 2023 in United States
Derivation MethodRank | Company | Click Share |
---|---|---|
1 | Digivac | 33.3% |
2 | Exair Corporation | 33.3% |
3 | Anger Associates Inc. | 16.7% |
4 | JJ Electronic | 16.7% |
Ranking as of January 2023 Globally
Derivation MethodRank | Company | Click Share |
---|---|---|
1 | Digivac | 33.3% |
2 | Exair Corporation | 33.3% |
3 | Anger Associates Inc. | 16.7% |
4 | JJ Electronic | 16.7% |
Derivation Method
The ranking is calculated based on the click share within the vacuum tube page as of January 2023. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.Number of Employees
Newly Established Company
Company with a History
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