2N3904 vs 2N2222

The 2N3904 and the 2N2222 are 2 of the most popular NPN bipolar junction transistors in the electronics market.

In case you're curious about which to use, or which one is better or superior than the other, in this article, we compare and contrast the 2 transistors.

Comparing transistors isn't extensive, as there are only a few very useful parameters that matter. Below is a table of the comparison and contrast of the transistors, with an explanation of what everything in the table means below it.

As described, the 2N3904 and the 2N2222 are both bipolar junction transistors (BJTs). This means they are both controlled by current applied to the base and provide current amplification at the collector-emitter end.

As they are both NPN-type BJTs, they are composed of 2 layers of N material sandwiching a layer of P material. This means that in a circuit, voltage and current are biased to them the same exact way- they both must receive positive voltage to the base and collector terminals in order to operate.

In these ways, the 2N3904 and the 2N2222 are both identical. They are also identical in the amount of voltage they can handle aross the collector-to-emitter terminals- both can handle up to 40V. In simplicity, this really means that 40V is the maximum amount of voltage that the transistor can tolerate minus the voltage drop across the load connected to the collector. For example, say, we applied 70V to the collector of the transistor and the load will consume 20V, this means that the remainder of the voltage will fall across the transistor, which will be 70V-20V=50V. This wouldn't be acceptable, since it exceeds the maximum VCEO. Since the 2N3904 and the 2N2222 have the same maximum VCEO voltage, there's no difference in regard to this aspect.

How they differ is that the 2N2222 can handle greater operating collector current. The collector current is the amplified current that flows from the emitter terminal to the collector terminal to power on a load that may be connected to the transistor. A 2N3904 can handle up to 200mA (milliamperes) of current flow from the emitter to collector terminal. A 2N2222 can handle up to 5 times that amount, since it can handle up to 1A (ampere) of current flow from the emitter to collector to power on a load.

So in this way, the 2N2222 does have superiority in that it can handle greater current. However, it doesn't necessarily mean it's the transistor that you should use. 200mA is still a great amount of current that will suffice to power most electronic components. Typical components that may require a transistor in order to be driven are motors, buzzers, solenoids, and high-power LEDs. These all normally require much less than 200mA to be powered on. Motors, for example, typically require in the range of about 75mA to power on. This means the 2N3904 will suffice perfectly fine for these applications. But, if you wanted to power several of them, for instance, you may need more current, what you would get from the 2N2222, up to 1A.

So the choice ultimately depends on how much current is needed. If you need less than 200mA, the 2N3904 or 2N2222 will work. If you need greater than 200mA but less than 1A, then the 2N2222 will be the one to use. And if you need greater than 1A at the output, then a darlington transistor such as the TIP122 transistor can be used, which can handle up to 5A of amplified current. And if you need greater current, the TIP3055 can handle up to 15A.

However, when you are dealing with electronics, unless you are in power electronics, you will pretty much never need amperage this high. These really are extreme conditions. Plus, currents this high need to be cautiously used because they can easily be lethal and can cause death.

Usually a 2N3904 will suffice for most circuits, but if you need more than 200mA, then you should use a 2N2222 instead.

Related Resources

How to Connect a Transistor as a Switch in a Circuit

How to Connect a (NPN) Transistor in a Circuit

Types of Transistors

Bipolar Junction Transistors (BJTs)

Junction Field Effect Transistors (JFETs)

Metal Oxide Semiconductor Field Effect Transistors (MOSFETs)

Unijunction Transistors (UJTs)

What is Transistor Biasing?

How to Test a Transistor