TIP122 Transistor

The TIP122 is an NPN Transistor.   In that format, we know that the base requires a voltage that is more positive than the emitter in order to allow current to flow from the emitter to the collector.    The location of the base, emitter and collector of a TIP122 are shown in the picture below.

The neat thing about this transistor is that it allows for as much as 5 amps of current going from the emitter through to the collector and as much as 120 mA going from the emitter through to the base.

Equally cool is the fact that you can have as much as a 100 volt difference from the collector to the emitter and as much as a 100 volt  between the collector and base.