Lamps. Types and purpose

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Kinds of lamps, EVD (electric vacuum device)

Many people think that the electric vacuum devices are already outdated, because they are uncopmatible with EVD.Our time is marked by a wide development of uniquely small radioelectronic devices. The dictionary includes a special term”nanotechnology”. It must be said that such an opinion is completely wrong. Of course such devices are no longer so widely used, they are replaced by diodes and transistors. But some industries can not work without them, thanks to the unique properties of EVD.


Often the electronic devices are called “vacuum tubes” (in common parlance) due to their similarity with incandescent lamps. EVD differ from the last ones in their purpose and functionality. Operation of this device is due to the principle of “acceleration / deceleration” of electrons in a vacuum space. Also the space inside the device can be filled with some kind of inert gas. Twenty years ago, such “lamps” were used almost in all radio electrical appliances.

Electric vacuum devices have different shells: glass, silver. The composition of any EVL includes a quantity of precious metals (gold, palladium, platinum, silver).


Cathode is a negative electrode, ensuring the emission of electrodes directly from the cathode. To improve emissions, the cathode is covered not only with silver, but also with thorium and barium. The cathode, which is used in EVD of considerable power, is made of tungsten.

The anode is a positive plate-shaped electrode, which can also be of a cylindrical or parallelepiped shape. It is produced from nickel, molybdenum, tantalum, graphite.

Grid protects the cathode from overheating, also, it is used to separate the anode from the cathode. The grid shape is spiral or lattice.

Until the mid-1950s, magnetrons and klystrons had been developed. And, these devices belong to the class of EVD, though they are not as simple as vacuum tubes.


Electric vacuum devices were used to create radioelectronic, technical devices in the fifties and nineties of the last century in all industries. Any TV, radio, oscilloscopes, various equipment, first computers, computers of those years necessarily contained EVD. But with the passage of time, the development of radio electronic production, precision instruments, the electrovacuum devices practically ceased to be used. It would seem that the years of “life” of this type of devices has ended, but it is not. Some branches of industrial production still do not work without them, because only an electric vacuum device can provide the technician with specified parameters, correct performance characteristics, especially in aggressive environments.

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