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What are Vacuum Tubes?

CRT monitors contain vacuum tubes.
Cathode ray tubes were common in monitors, display screens and televisions for decades.
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  • Written By: Malcolm Tatum
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  • Last Modified Date: 29 November 2014
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Vacuum tubes are electronic devices that are configured to provide amplification to electronic signals. For most of the first half of the 20th century, the vacuum tube was in integral part of radio and television technology. Over time, many forms of the tubes have become obsolete as newer and more robust amplifiers have become available. However, there are some forms of vacuum tubes still in common use.

Sometimes referred to as an electron tube, vacuum tubes are also known as valves in the United Kingdom. In general, the tubes utilize a great deal more power than any type of transistor currently on the market. It is not unusual for vacuum tubes to require in the range of 400 volts. There are some examples of thermionic valves that require power supplies that move into the kilovolt range.

From the 1960’s and forward, vacuum tubes became less and less common in household receivers such as televisions and radios. The newer transistor technology, which was considerably less bulky and required only a fraction of the power input for operation, quickly became a favorite with consumers. Young people especially were happy with the newer technology, as it made it possible to carry a radio small enough to fit into a pocket and enjoy music anywhere.

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While vacuum tubes may have lost some popularity after the advent of the transistor, there were to begin making a comeback as desktop computers came into being. The cathode ray tube, one common form of vacuum tubes, proved to be ideal for computer monitors. Many manufacturers found using this type of tube allowed for a vibrant and crisp image display, especially as the older DOS formats gave way to the newer Windows technology.

There is also a steady movement to re-integrate vacuum tubes into other devices as well. Proponents of the use of vacuum tubes note that not only do the tubes offer brilliant imaging and excellent sound quality; they also demonstrate a level durability that is not often found with transistors. Vacuum tubes tend to handle temporary overloads of current with more efficiency than the newer technology, which helps to make them less susceptible to shorting out and requiring replacement.

At the same time, there has not been much in the way of advancement in the basic design of vacuum tubes. The devices are still large in comparison to a transistor and require a larger power supply. Electronics professionals also note that vacuum tubes are also more likely to present a risk of some sort of electric shock, owing to the larger power supply that is required to drive the function of the tubes.

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Grivusangel
Post 2

@Wisedly -- Well, that explains a lot. My friend's dad is an antique radio buff, and has griped about having a hard time finding tubes for the old sets. Now I know why.

We bought a TV in the very early 70s that was mostly tube-powered. When you turned it on, you had to wait a minute or two for it to warm up before you got a picture. The audio usually came up first. Then, it might be another couple of minutes before the picture looked right. This process took even longer for a color TV.

Wisedly33
Post 1

Vacuum tubes are also nearly impossible to find, since only a very few are made in the US nowadays. My hubby plays the church organ and the organ is way older than either one of us! It still uses vacuum tubes, and there's like one man in a tri-state area who can still repair it -- and it's when he feels like showing up.

Every tube on the organ needs to be replaced, but the repairman said we would never find tubes for it because the only place they're made in the large sizes are in China and Russia. That organ sounds like a bowl of Rice Krispies -- snap, crackle and pop!

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