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Vacuum tube:
The vacuum tube, also called the electron tube or valve, is one of the first components of an electronic signal amplifier in electronics. Part of the cathode electron-emitting, control grid, acceleration grid, and lead anode (screen) enclosed in a glass container (usually a glass tube) are burned at the base of the tube.
The principle is, the electric field is used to inject an electronic fluctuation signal at the control gate into the vacuum, and a different parameter signal data is obtained from the anode after amplifying the signal or response frequency. The inside of the glass bottle is removed to facilitate the free flow of electrons, and the oxidation loss of the filament can be effectively reduced.
Types of vacuum tubes:
Vacuum tubes are solid-state devices or also known as thermionic valves. Vacuum tubes operate on the principle of thermionic discharge. Thermionic emission simply means the removal or removal of electrons from a metal surface. We can divide vacuum tubes into four parts
- Vaccum diode
- Vaccum triode
- Vaccum tetrode
- Vaccum pentode
Vacuum diode
The vacuum diode consists of three parts of a plate, a cathode and a filament. The vacuum diode plate is made of Nickel material and coated with Barium oxide. Cathode is also made of Nickel. The vacuum tube is made of Tungsten and all the tools are removed from the glass tube. We will use the vacuum diode as a p-n junction diode. But the worst part of the vacuum tube is that it forms a cost gap between the cathode and the filament. As a result the efficiency of the metal decreases.
Vacuum triode
The vacuum triode also contains the same components as the vacuum diode but an additional component is added to the vacuum triode to increase its efficiency called grid. A vacuum triode is also called a sound device because it operates on sound frequencies. In the machine vacuum triode grid terminal is very close to the cathode terminal. The grid in the vacuum triode is known as the control grid and is in a helical position. The purpose of the grid is to transfer electrons from the cathode to the plate. The grid is always kept in a bad condition related to the cathode. Due to the grid the formation of space costs will stop and current efficiency will increase. We can use a vacuum triode as an amplifier but when the high frequency cannot function as an amplifier because the power between the different electrons increases.
Vacuum tetrode
The vacuum tetrode consists of a four-electrode plate, a control grid, a screen grid and a cable. In the vacuum tetrode a second discharge will occur. The screen grid is made of wire mesh as a structure. The main purpose of installing a screen grid is to reduce the effect of inter electron capacitance. Due to the presence of the screen grid terminal there is a screen or protection between the plate and grid capacity. The disadvantage of a vacuum tetrode is that it has kinks in it. Due to the presence of kinks in the element it resists the change of voltage plate to high voltage only.
Vacuum pentode
The vacuum pentode consists of a five-electrode plate, a pressure grid, a screen grid, a control grid and a cathode. Sppressor grid was added to overcome the formation of kinks in the vacuum tetrode. The Suppressor grid is always connected to a high tension voltage. The function of the pressure grid is to compress the output of an electron from the plate terminal to the cathode terminal. In this case the effect of inter electron capacitance becomes insignificant. We can use the vacuum pentode as a video amplifier or a radio frequency amplifier.
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