F or decades before the arrival of the transistor, it was the vacuum tube that formed an integral part of all electronic devices. In fact, it actually performed the same functions as the transistor, acting as both a switch and an amplifier. This might lead you to wonder why the transistor was regarded as such a revolutionary breakthrough for the electronics industry. In truth, it was not what the transistor did, but how it did it that made the transistor so vastly superior over the vacuum tube.

There were many practical problems concerning the vacuum tube. It was not only expensive, but also bulky. These two factors meant that any devices that made use of the vacuum tube would also be large, clumsy and expensive. The vacuum tube also heated up very quickly, which was a major contributing factor to the next major problem: unreliability. The first computers were made with vacuum tubes, but the vacuum tubes burned out frequently. Moreover, due to their bulky nature, such computers would occupy several large rooms. Another bizarre problem was also encountered. The vacuum tube's lights attracted moths, which short-circuited the computer. Something better was needed, and that something eventually came in the form of the transistor.

The transistor was the perfect replacement for the vacuum tube. They were not only cheaper, but also smaller, and more reliable. The invention of integrated circuit in 1958 allowed literally millions of transistors to be packed together on a single silicon chip, allowing components to work at lightening-fast pace. The better and more compact transistor also allowed for the invention of later electronic devices such as radios and hearing aids, revolutionising the electronics industry.

Vacuum tubes have now been almost entirely replaced by the faster and more reliable transistors. Tubes still play an important role in certain applications, however, such as in power stages in radio and television transmitters, and in military equipment that must resist the voltage pulse (which destroys transistors) induced by an atmospheric nuclear explosion.

                                                      Transistors vs Vacuum Tubes


Vacuum Tube



Excellent Reliability

Very Unreliable

Very Small

Large and Bulky

Stable Temperatures

Get Hot Quickly

Very Fast


Found in Large Numbers

Found in small numbers

Cannot carry very high voltage

Can carry high voltage
(Main factor responsible for the survival of vacuum tubes in some appliances)