2N3904 is a widely used bipolar junction transistor. It is used for general purpose low power switching or amplifying applications. It is designed for low power and current, moderately high speeds and medium voltage.
It has a maximum collector current of 200mA and can therefore be used to drive loads under 200mA. It has a dissipation of 625 milliwatts hence can be used for RF signal amplification and audio purposes.
It has three layers in it, and all are different from each other in terms of the concentration of the dropping and the size. The centred layer is very small and has the lowest concentration compared to the other two layers. The topmost layer is bigger in size and highly doped than the rest.
You can use the transistor in any electronic application falling under its characteristics. You can drive a variety of loads with these transistor-like relays, LEDs and high power transistors.
2N3904 datasheet
According to its datasheet, some of the main specs of the transistor are:
- Available in To-92 package
- Collector base voltage of 60V
- The collector-emitter voltage of 40V
- Base emitter voltage of 6V
- Continuous collector current of 200mA
- DC Current gain of 300hfe
The following are the key application areas for the transistor:
- Darlington pairs
- Audio amplifier stages
- Audio preamplifier stages
- Sensor circuits
2N3904 pinout
2N3904 has three pins. Pin 1 is the emitter pin through which currently drains from. Pin 2 is the base pin that controls how the transistor is biased. The third pin is the collector pin through which current flows from.
Check the pinout diagram above.
2N3904 Equivalents and Replacement Details
Equivalents of 2N3904 are 2N2222, SS9013, S8050 and 2N4401. Even if these are its equivalents, some transistors might have different pin configurations from 2N3904, so be sure to check before replacing a circuit.
