Project – 2N2222 NPN Switching Transistor

The 2N2222A is a common NPN Bipolar Junction Transistor (BJT) is used for general purpose low power amplifying or switching actions. As it is an NPN transistor, so collector and emitter will be left open when no signal is at the base and when a signal is provided to the base terminal, then the emitter and collector will be closed i.e. they will start conducting as BJT will operate in Saturation Region. 2N2222A has a gain value of 110 to 800, this value determines the amplification capacity of the transistor. The maximum amount of current that could flow through the Collector pin is 800mA, hence we cannot connect loads that consume more than 800mA using this transistor. To bias a transistor, we have to supply current to base pin, this current (I_B) should be limited to 5mA. It can be used in switching applications with current up to 800mA, in speed control of motors, also it can be used in Darlington Pair.

Specifications

• Bi-Polar high current NPN Transistor
• DC Current Gain (h_FE)is 100 to 300
• Continuous Collector current (I_C) is 800mA
• Emitter Base Voltage (V_BE) is 6V
• Collector-Emitter Voltage (V_CE) is 40V
• Base Current (I_B) is 5mA maximum
• Available in To-92 Package
• Rise Time 25nSec, Fall Time 60nSec

The 2N2222A is very much similar to BC547 BJT and 2N3902 BJT except it can allow more current than BC547 and can dissipate 652mW of power. To use it as a Switch or amplifier, you just have to forward bias Base Emitter Junction but care should be taken to limit the base current as emitter can only allow up to 800mA of the current to power the device.