A transistor is a electronic device made by semiconductor used to amplify electrical power or switch electronic signals . It is composed of semiconductor material with at least three terminals for connection to an external circuit. Two types of transformer, PNP and NPN. The arrow points (Emitter) in a different direction depending on whether the transistor is PNP or NPN.
Transistors can be divided into two major groups: bipolar and unipolar (also called Field Effect Transistors, or FETs). While there are several differences between the two types, the most important difference is this:
* Bipolar transistors vary current to control voltage.
* FET transistors vary voltage to control current.
FETs also have three sections. These sections are referred to as the gate, the source, and the drain .
* The gate approximates the function of the base.
* The source is similar to the emitter.
* The drain is similar to the collector.
Transistors have many other ratings that are similar to those for diodes. Transistors can be rated according to the following conditions:
* How fast the transistor can turn on and off.
* How much heat the transistor can handle.
* How much current leaks through a transistor when the transistor is supposed to be turned off.
Transistors are used in many applications, including radios, electronic control modules and other solid state switches.