This part is a kind of semiconductor called ST2N3904.

Function of this product has NPN Silicon Epitaxial Planar Transistor.

Manufacturers : SEMTECH ELECTRONICS

Image and pinout :

Some of the text within the PDF file :

ST 2N3903 / 2N3904 NPN Silicon Epitaxial Planar Transistor for switching and amplifier applications. As complementary types the PNP transistors ST 2N3905 and ST 2N3906 are recommended. On special request, these transistors can be manufactured in different pin configurations. TO-92 Plastic Package Weight approx. 0.19g Absolute Maximum Ratings (T a = 25 oC) Symbol Value Collector Base Voltage VCBO 60 Collector Emitter Voltage VCEO 40 Emitter Base Voltage VEBO 6 Collector Current IC 100 Peak Collector Current Power Dissipation ICM 200 Ptot 5001) Junction Temperature Tj 150 Storage Temperature Range TS -55 to +150 1) Valid provided that leads are kept at ambient temperature at a distance of 2 mm from case G S P FORM A IS AVAILABLE Unit V V V mA mA mW OC OC РАДИОТ [ ... ]

ST2N3904 PDF Datasheet Download