Once a transistor was called a radio, but in this article we will not talk about a radio. So what is a transistor and how does it work.
There is such a class of materials, for its properties called semiconductors. Their distinguishing feature is conductivity - they can be both conductors of electric current and dielectrics, i.e. insulators and do not conduct electric current.
This material is used to make a transistor, a semiconductor device widely used in industry and serving as the basis for almost all modern electronics.
Without touching on the manufacturing technology, types of transistors, their application, we just note that there are transistors of different types, for example, an npn transistor. He got this name because of the material used and the type of conductivity. What has been said is still sufficient to delve into the manufacturing technology and the variety of transistors now.
How does a transistor work? It is designed to control electric current, is structurally manufactured in a metal or plastic case and has three terminals, called an emitter, base, collector. The name of the conclusions already speaks of their purpose: the emitter emits electrons, the base controls them, the collector collects them. All these processes occur inside the transistor.
To understand how a transistor works, consider a much simpler example - a water tap.
He also has three conclusions - one water enters the tap, another pours out of the tap, the third is a valve that controls the operation of the tap. When the valve is open, water flows freely through the valve; when the valve is closed, water does not flow. This is an imitation of one of the options for how the transistor works. This mode of operation is called key - the transistor is open - an electric current flows , or is closed, then the current does not flow. To open the transistor, voltage is applied to the base, if there is voltage, then the transistor is open, if not, then it is closed. Everything happens as in a water tap, the valve is open - water is flowing, the valve is closed - there is no water.
The operation of the transistor was considered above when it is used as a key: it is either closed or open. However, there are other modes of operation. Again, as an example, consider a water tap. If you slightly open the valve, then the water from the tap will pour constantly, and the pressure of the water will be determined by how much we opened the tap.
The transistor has approximately the same operating mode. Voltage is supplied to its base, it opens, and current flows through it. By changing the magnitude of the voltage at the base, you can adjust the magnitude of the current passing through the transistor. A complete analogy with the position of the valve on the tap: more open - more water flows (i.e. current for the transistor); less open - less water flowing (current for the transistor). This mode of operation of the transistor is called amplifying, when with the help of a small voltage supplied to the base, it is possible to control a significant current removed from the collector.
In conclusion, it should be noted that transistors can be of different types, everything is determined by the material used in the manufacture. They can differ in power, can control and pass through themselves significant currents of electric current. Transistors can be of different designs. There are other modes of operation of transistors that differ from those considered. But the basic idea of how the transistor works is given above.
All of the above is approximate, but still allows you to understand the operation of the transistor. In fact, the operation of the transistor is much more complicated. There are special parameters that you can use to use the formulas to calculate and set the required mode of operation, but this is a completely different topic for conversation and for another article.