2N3904 NPN Transistor

• 2N3904 – NPN Transistor
• 2N3904�is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin. 2N3904 has a gain value of 300; this value determines the amplification capacity of the transistor. The maximum amount of current that could flow through the Collector pin is 200mA, hence we cannot connect loads that consume more than 200mA using this transistor. To bias a transistor we have to supply current to base pin, this current (IB) should be limited to 5mA
• When this transistor is fully biased then it can allow a maximum of 200mA to flow across the collector and emitter. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (V­CE) or Collector-Base (VCB) could be 40V and 60V respectively. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region and the Base Emitter voltage could be around 600 mV.

2N3904 Equivalent NPN Transistors:

• BC549, BC636, BC639, 2N2222 , 2N2222, 2N2369, 2N3055, 2N3906, 2SC5200

Applications:

• Driver Modules like Relay Driver, LED driver etc…
• Amplifier modules like Audio amplifiers, signal Amplifier etc…
• VCB and VBE is high hence can be used to control voltage loads up to 40V
• Commonly used in TV and other home appliances