2N3904 General Purpose BJT NPN Transistor

The 2N3904 is an NPN silicon epitaxial planar bipolar junction transistor used for general-purpose low-power amplifying or switching applications. It is designed for low current and power, medium voltage, and can operate at moderately high speeds. 

The useful dynamic range extends to 100 mA as a switch and to 100 MHz as an amplifier.

Applications:

#. It is well suited for tv and home appliance equipment.
#. It can be used as a small load switch transistor with high gain and low saturation voltage.
#. It can be used to build up to 100 MHz amplifier.