The 2N3055 is perhaps the most iconic NPN power transistor in the history of electronics. Designed for high-power switching and linear amplification, it is famously housed in the TO-3 metal can package, which allows for superior heat dissipation. It has been a cornerstone in the design of regulated power supplies, DC-to-AC inverters, and high-fidelity audio power amplifiers for decades. While newer MOSFETs have replaced it in some modern applications, the 2N3055 remains a favorite for engineers and hobbyists due to its extreme ruggedness and ability to handle high current surges without failure.
2N3055 Pinout (TO-3)
The 2N3055 uses a metal “can” package where the body of the transistor itself serves as one of the terminals. When looking at the bottom of the transistor with the two pins positioned closer to one side, the configuration is as follows.
| Pin | Terminal | Function |
| Pin 1 | Base (B) | Control terminal for the transistor |
| Pin 2 | Emitter (E) | Current output terminal |
| Case | Collector (C) | The metal housing acts as the collector |
Technical Specifications
- Transistor Polarity: NPN
- Collector-Emitter Voltage (VCEO): 60V
- Collector-Base Voltage (VCBO): 100V
- Emitter-Base Voltage (VEBO): 7V
- Collector Current (IC): 15A (Continuous)
- DC Current Gain (hFE): 20 to 70 (at 4A)
- Max Power Dissipation (PD): 115W (with proper heatsink)
- Operating Temperature: Up to 200°C
Key Features & Benefits
- High Current Capacity: Able to handle up to 15A, making it ideal for heavy-duty power supplies.
- Superior Heat Dissipation: The metal TO-3 package provides a large surface area for thermal transfer.
- Low Saturation Voltage: Ensures efficient operation in high-power switching applications.
- Proven Reliability: A time-tested component known for its ability to survive electrical stress.
Common Applications
- Linear Power Supplies: Acting as the pass transistor in high-current voltage regulators.
- Audio Power Amplifiers: Used in the output stages of high-fidelity sound systems.
- DC Motor Control: Switching and regulating speed for large DC motors.
- Solenoid Drivers: Managing high-current inductive loads in industrial machines.
2N3055 Equivalent & Substitutes
- MJ15003 (Higher power/voltage alternative)
- TIP3055 (Equivalent in a plastic TO-247 package)
- 2N3771 (Higher current alternative – 30A)
- 2SC5200 (Modern high-fidelity audio equivalent)
Related Tutorials on ElxHub
- Basics: Learn more in Transistors – Basics, Types, and Working
- Signal Shifting: Learn how to bridge logic levels in our Logic Level Shifter Tutorial
- Selection Guide: Compare power options in our Ultimate Transistor Selection Guide
Conclusion
The 2N3055 remains a legend in the power electronics world. Its classic metal design and massive current handling capabilities make it a reliable choice for any project where power and durability are the top priorities. Even in the age of modern silicon, the 2N3055 continues to be a staple for building high-quality, long-lasting power equipment.
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