NPN Transistor - 2N3904
From bildr
This Transistor is designed as a general purpose NPN amplifier and Electronic Switch. The useful dynamic range extends to 100 mA as a switch and to 100 MHz as an Amplifier.
It is a 200 milliamp, 40 volt, 625 milliwatt transistor capable of amplifying up to 100 MHz, with a beta of at least 100. It is used in a variety of analog amplification and switching applications.