Transistor, is a device having three electrodes, also referred to as bipolar transistors, transistor, essentially two PN junctions on a semiconductor substrate to be separated into a base region, emitter region and the collector region, thereby leads to the base, the transmitter and collector three electrodes, according to the structure can be divided into the NPN and PNP type.
The transistor is a current controlled current semiconductor device having a current amplification, used as a switch, substitution and other effects, are now widespread in various circuits.