Ask most people about modern electronics and they might say something about an integrated circuit or motherboards. After all, those drive everything from smart TVs and smartphones to desktop computers and tablets.
Ask those same people about vacuum tubes or an electron tube. If you’re lucky, they might say something about mad scientists from 40s movie serials. Yet, the vacuum tube is not only alive and well, but likely found in your very own microwave.
Since most people don’t know about them anymore, you might ask, “How does a vacuum tube work?” Keep reading for a quick guide to what vacuum tubes are and how they work.
What Is a Vacuum Tube?
The simplest version of vacuum tube technology, called a diode, is a very simple device. It is literally two electrodes inside of a glass tube.
You put a cathode on one end of the tube and an anode on the other. A cathode carries a negative charge, while anodes carry a positive charge. This device conducts electricity.
But why do they call them vacuum tubes? The inside of the glass tube is a vacuum, as it has no gases in it.
Thermionic Emission
Before you can really understand a vacuum tube, you must understand a little about electricity and thermionic emission. At its most basic, electricity is nothing more than moving electrons that have a negative charge. That’s what moves through the power lines and your devices’ cords.
Thermionic emission is a process where you heat a cathode. As it heats up, the cathode will release negatively charged electrons. Those available electrons create an opportunity.
That brings us to how vacuum tubes work.
How Does a Vacuum Tube Work?
In the basic vacuum tube described above, you heat up the cathode inside the tube. The cathode sheds electrons. Of course, that just leaves electrons floating around the tube.
That’s where the anode comes into the picture. The positive charge of the anode attracts all of those stray electrons, creating electrical flow. Removing the gas from the tube means that nothing gets in the way of the moving electrons.
Of course, there are several types of vacuum tubes, such as triodes and pentodes. These tubes use extra parts, such as control grids and additional electrodes. These additional parts allow for electricity flow control and current amplification.
In addition to microwaves, you still see vacuum tubes in musical amplifiers, electron microscopes, and field electron emitters.
Vacuum Tubes and You
The question of how does a vacuum tube work is less complicated than it sounds at first glance. The vacuum tube works on the basis of a few basic principles.
A heated cathode will shed electrons. The positive charge of the anode will attract the electrons. The vacuum inside the tube improves the efficiency of that electron flow.
Once you know that, you can explain basic vacuum tubes to your friends or family.
Looking for more insights into new or old technology? Check out the articles over in our Technology section.
