Vacuum tubes are a type glass tube device, which has had its gas removed, creating a vacuum space. It is comprised of electrodes that are designed to control electron flow between the electrodes sealed inside the vacuum tubes. Unlike transistors, these tubes can be easily replaced by the user.
Vacuum tubes utilise a principal called thermionic emission in which a metal is heated allowing the electrons to be loosened up. This causes the positively charged anodes to attract the negative electrons emitted by the cathodes by causing an electric current to flow into the anode and out of the cathode.
An advantage of vacuum tubes is that they have a wider dynamic range than transistors circuits. This is mainly attributed to their higher operating voltages and overload tolerances.
There are a variety of vacuum tubes available such as;
Vacuum tubes have a wide range of application in electronic type devices such as;