uneeds BC547 NPN General Purpose Transistor (BJT) 45V 100mA TO92 Package (Pack of 50) NPN Transistor  (Number of Transistors 50)

BC547 is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.