Browse DigiKey's inventory of NPN TransistorsNPN. Features, Specifications, Alternative Product, Product Training Modules, and Datasheets are all available. 2N3904 Transistor and Specifications. 2N3904 Datasheet. 2N3904 Circuits. The 2N3904 is common general-purpose low-power NPN transistor used amplifying or switching applications. It is typically used for low-current, medium voltage, and moderate speed purposes. Browse DigiKey's inventory of NPN TransistorsNPN. Features, Specifications, Alternative Product, Product Training Modules, and Datasheets are all available. Since the 2N3904 is an NPN transistor, that means the base needs positive biasing (appropriate voltage levels and resistance) to turn on the collector emitter junction for proper current flow. Use of a load resistor (R1 above) is also important so there is not too much current being driven through the LED and transistor. 2N3904 Datasheet, 2N3904 PDF, 2N3904 Data sheet, 2N3904 manual, 2N3904 pdf, 2N3904, datenblatt, Electronics 2N3904, alldatasheet, free, datasheet, Datasheets, data ... AUK Corp catalog First Page, datasheet, datasheet search, data sheet, datasheets, Datasheet search site for Electronic Components and Semiconductors, integrated circuits, diodes, triacs, semiconductors Schematic of very Simple preamplifiers using 2N3904. In electronics, a common emitter amplifier is used as a voltage amplifier. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common.