What is Vacuum Tube ?

Vacuum tubes produce superior sound quality.

Vacuum tubes using this form of cathode coating have layer of a mixture of barium

strontium oxides coating the surface of the cathode

Vacuum tubes are huge compared

this form of heating is less efficient than the directly heated option.

Vacuum tubes generate more heat

High voltages are required to operate the vacuum tubes.

As a result, some specialist tubes or valves that use tungsten or thoriated tungsten filaments sometimes use direct heating techniques.

Vacuum tubes consume more power.

The electrons flowing between the cathode and the anode form a cloud of electrons

High cost.

Failure rate is high.

However if the potential applied to the anode is sufficiently high

so that electrons will flow toward the anode.

In this way electrons are able to move across the vacuum

Vacuum tubes occupy more space than the transistors.

the glass envelope of the vacuum tube / valve, the circuit is completed and current flows.

As the potential is increased on the anode, so the current increases.

The theory behind the operation of a vacuum tube is based on a concept known as thermionic emission.

Eventually a point is reached where the space change is completely neutralised and the maximum emission

Although all areas of a vacuum tube have a space charge, it is of particular importance in the cathode region as it determines elements including the maximum emission.

As other electrodes are added into the evacuated envelope, the space charge concept can be applied to the whole operational area.

Understanding these concepts provides the basis behind understanding how a vacuum tube works.

As other electrodes are added into the evacuated envelope, the space charge concept can be applied to the whole operational area.

The space charge concept plays a crucial role in determining the flow of current in any thermionic device.