The 2N3904 is a widely used NPN bipolar junction transistor (BJT) suitable for general-purpose low-power applications. The PNP complementary pair of this transistor is 2N3906. The 2N3904 transistor typically comes in a TO-92 package with three pins. BC548, BC549, BC546 (Pin CBE), 2N2222 (Pin EBC) Material of Transistor: Si. Polarity: NPN. Max.