Transistor, the full name should be semiconductor triode, also known as bipolar transistor, transistor, is a kind of semiconductor device that controls current. Its function is to amplify the weak signal into an electrical signal with a larger amplitude value, and it is also used as a contactless switch.

The triode is one of the basic semiconductor components, which has the function of current amplification and is the core component of the electronic circuit. The triode is made of two PN junctions very close to each other on a semiconductor substrate. The two PN junctions divide the entire semiconductor into three parts. The middle part is the base area, and the two sides are the emitter and collector areas. The arrangement is PNP And NPN two kinds.