NPN vs. PNP Transistor: Key Differences, Uses & How to Choose
NPN and PNP transistors are two kinds of bipolar junction transistors. An NPN turns on when a positive voltage goes to its base; a PNP turns on when its base is pulled below its emitter. Same job—switching or amplifying—but opposite polarity. Beginners see three legs and identical packages, so they swap them and wonder why…