How do Transistors work?
Almost like a flush toilet, indeed…
Transistors are the building blocks of our electronic gadgets: from smartphones to computers, toys, cooking devices, cleaning tools, etc.
Despite their ubiquity, only a few people know about how they work. In fact, understanding their principles of operation is not so hard.
The diode: a transistor building block
In order to understand how a transistor work, we need to understand what a diode is. In fact, a transistor, in practice, is nothing but two diodes.
A diode, essentially, works as a valve for electric current. It lets a flow of electrons flow in one direction only, opposing the movement of electrons in the opposite direction, just as a water valve lets a flow of water flow in one direction only.
Diodes consist of two semiconductor crystals doped with different atomic species so that, at their junction, they exhibit an electric field that prevents charges from flowing in one direction, while accelerating those moving in the opposite direction. Diodes like these are called p-n diodes, because they are made of a p-type semiconductor crystal joined with an n-type one. p and n refer to the sign (positive or negative) of their charge carrier.
