2N2222 NPN bipolar junction transistor
The 2N2222 is a common NPN bipolar junction transistor used for general purpose low-power amplifying or switching applications. It is designed for low to medium current, low power, medium voltage, and can operate at moderately high speeds. It is made in the TO-18 metal can as shown in the picture. Replacements are commonly available now in the cheaper TO-92 packaging, where it is known as the PN2222 or P2N2222, which has similar specifications except for the lower maximum collector current.
The 2N2222 is considered a very common transistor, and is used as an exemplar of an NPN transistor. It is frequently used as a small-signal transistor, and it remains a small general purpose transistor of enduring popularity.
The JEDEC registration of a device number ensures particular rated values will be met by all parts offered under that number. JEDEC registered parameters include outline dimensions, small-signal current gain, transition frequency, maximum values for voltage withstand, current rating, power dissipation and temperature rating, and others, measured under standard test conditions. Other part numbers will have different parameters. The exact specs depend on the manufacture case type and variation. Therefore it is important to reference the datasheet for the exact part number and manufacturer.
|40 V||800 mA||500 mW/1.8 W||300 MHz|
All variations have a beta or current gain (hFE) of at least 100 in optimal conditions. It is used in a variety of analog amplification and switching applications.
The BC548 is a low voltage, low current; general-purpose switching transistor in a TO-92 package.
The 2N3904 is an NPN transistor that can only switch one-third the current of the 2N2222 but has otherwise similar characteristics.
The 2N2219 is very similar with higher power dissipation rating.
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- Datasheet for Fairchild Semiconductor's equivalent PN2222 (PDF)
- 2N2222 Transistor History, Packaging and Datasheet
The 2N2222, 2N2905, and 2N3055 devices, for example, which date back to the 1960s but have been improved, are still useful in new designs and are still popular for experimenters.
Typical examples are the well known NPN and PNP industrial and military types, 2N2222 and 2N2907, which have been used for over four decades and are still being used in many designs.
Since its initial product launch by Motorola at the 1962 IRE Convention, the 2N2222 has become the most widely used and universally recognized transistor of all time. Billions of units have been manufactured over the past 45 years and there is continuing high volume annual production.
Learn to keep an eye open for the following transistors, as they're among the most useful, inexpensive, and popular types: PN2222/PN2907 These are general-purpose NPN/PNP transistors that can drive some good amounts of power. They're listed together because they're complementary transistors.