Table of Contents
📘 Introduction
The 2N2222 is a widely used NPN bipolar junction transistor (BJT) designed for general-purpose low-power switching and amplification. It’s one of the most common transistors found in educational and hobby electronics projects due to its reliability, versatility, and affordability.
Originally manufactured in a metal TO-18 package, modern variants are also available in plastic TO-92 packages.
🔌 Pinout (TO-92 Package)
Here is the pin configuration when looking at the flat face of the TO-92 package, with the pins facing downward:
| Pin No. | Name | Function |
|---|---|---|
| 1 | Collector | Current output terminal |
| 2 | Base | Controls transistor switching |
| 3 | Emitter | Current flows out through this pin |
✨ Features
| Parameter | Details |
|---|---|
| Type | NPN |
| Max Collector Current (Ic) | 800 mA |
| Max Collector-Emitter Voltage (Vce) | 40 V |
| Max Collector-Base Voltage (Vcb) | 75 V |
| Max Emitter-Base Voltage (Veb) | 6 V |
| Max Power Dissipation | 500 mW (in TO-92) |
| DC Current Gain (hFE) | 100 – 300 |
| Transition Frequency (fT) | 250 MHz |
| Package | TO-18 (metal), TO-92 (plastic) |
⚙️ Applications
- 🔄 Switching low-power loads
- 🎙️ Audio signal amplification
- ⚡ Oscillator circuits
- 🧪 Educational electronics
- 🔋 Battery-powered projects
- 📡 RF signal circuits (low frequency)
🔁 Alternatives / Equivalents
Here are some compatible or functionally similar transistors to the 2N2222:
| Alternative | Notes |
|---|---|
| PN2222 | Plastic version; similar specs |
| BC547 | Lower current rating, common NPN |
| 2N3904 | Lower power, commonly used NPN BJT |
| S8050 | Chinese equivalent, similar use |
| SS8050 | Higher gain, high-current NPN |
⚠️ When replacing, always check voltage and current ratings for compatibility.
