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WHAT IS IT?
Vacuum tubes, or electron tubes, are analog devices used to control and modify the flow of electricity. They were invented in the early 1900s based on similar principles of the incandescent lightbulbs. As current flows into the airless glass bulb, electrons radiate from a heated cathode and are attracted to an anode before leaving the tube. Since the anode is not heated, it will not re- emit electrons, forming an electrical one- way valve. This is the simplest version of a vacuum tube, but once electrical flow can be controlled in this way, additional elements can be added to modify the current to perform other functions.
- This was key to the development of radios, TVs, radars, etc.
- As technology advanced, transistors eventually replaced tubes.
- Helped create modern electronics, but are now novelty items. Put on your desk to invoke curiosity and invite interesting conversation.
- Look up the model number of you tube to find out it's function!
Please allow for slight variations in size of tube
These items come in their respective vintage boxes
A vacuum tube, an electron tube, valve (British usage) or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as a thermionic tube or thermionic valve uses the phenomenon of thermionic emission of electrons from a hot cathode and is used for a number of fundamental electronic functions such as signal amplification and current rectification. Non-thermionic types, such as a vacuum phototube however, achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube.
The simplest vacuum tube, the diode, invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—from the cathode to the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grids.
These devices became a key component of electronic circuits for the first half of the twentieth century. They were crucial to the development of radio, television, radar, sound recording and reproduction, long-distance telephone networks, and analog and early digital computers. Although some applications had used earlier technologies such as the spark gap transmitter for radio or mechanical computers for computing, it was the invention of the thermionic vacuum tube that made these technologies widespread and practical, and created the discipline of electronics.
In the 1940s, the invention of semiconductor devices made it possible to produce solid-state devices, which are smaller, more efficient, reliable, durable, safer, and more economical than thermionic tubes. Beginning in the mid-1960s, thermionic tubes were being replaced by the transistor. However, the cathode-ray tube (CRT) remained the basis for television monitors and oscilloscopes until the early 21st century. Thermionic tubes are still used in some applications, such as the magnetron used in microwave ovens, certain high-frequency amplifiers, and amplifiers that audio enthusiasts prefer for their "warmer" tube sound.
Not all electronic circuit valves/electron tubes are vacuum tubes. Gas-filled tubes are similar devices, but containing a gas, typically at low pressure, which exploit phenomena related to electric discharge in gases, usually without a heater.
My Dad did television repair when I was a kid. He had shelves of these tubes at the shop. I bought this to reminisce, and because these items are fascinating remnants (unless you use a tube amp for your guitar). Great condition and even came in the old box!