2N3904 NPN Transistor

2N3904 NPN Transistor  which is normally used for fast switching and amplification purposes. In a few embedded circuits, its also used as a switch. You should also have a look at 2N3904 Pinout, if you are planning to work on this transistor.

Basics of 2N3904

• 2N3904 is an NPN transistor.
• 2N3904 is a current controlled transistor and that’s why comes in the category of Bipolar Junction Transistors, abbreviated as BJT.
• It has 3 terminals, which are:
  • Emitter.
  • Collector.
  • Base.
• Maximum current rating of this BJT transistor is 200mA.
• Maximum voltage rating of 2N3904 is 40V.
• Collector-Emitter Voltage Vceo of this transistor is 40V.
• Emitter-Base Voltage Vebo of 2N3904 is 6V.
• Collector-Base Voltage Vcbo of 2N3904 is 60V.

Working of 2N3904

• 2N3904 has 3 layers in it i.e. single P doped layer embedded between two N doped layers.
• These 3 layers are different from each other in terms of size and concentration of doping.
• The centred layer is very small in size and is low concentrated as compared to the other two N doped layers.
• Collector layer is bigger in size than the other two layers and thus highly doped.
• A small current on the P doped layer transforms into a higher current on other two terminals.

Applications of 2N3904

There are numerous applications of 2N3904 and is most commonly used in projects where below conditions are required:

• Fast switching.
• Pulse Width Modulation.
• Current Amplification.
• Automatic switching.

So, that was all about this Bipolar Junction transistor named as 2N3904. If you are working on this transistor then I would suggest you to first design its Proteus Simulation, as its always the best strategy to work on simulation before working on hardware, as you can sort out all the problems beforehand. If you get into any trouble then ask in comments and I will try my best to resolve your issues.