2N3904 NPN Transistor

The 2N3904 is a silicon NPN bipolar junction transistor (BJT) designed for general-purpose low-power amplifying and switching applications. It is famous for its fast switching speeds and high frequency response (up to 300MHz). Housed in a standard TO-92 through-hole package, it is a favorite for students and engineers across Pakistan for prototyping on breadboards and teaching the fundamentals of semiconductor physics.

Key Features 

• Universal Compatibility: The go-to NPN transistor for almost all low-current switching tasks.

• High-Speed Switching: Excellent for Pulse Width Modulation (PWM) and fast digital logic.

• Wide Gain Range: Provides a stable DC current gain (hFE​) between 100 and 300.

• Compact & Reliable: The TO-92 package is durable and fits perfectly into standard 0.1″ pitch breadboards.

• Complementary Pair: Works seamlessly with the 2N3906 (PNP version) for complex push-pull circuits.

Technical Specifications 

Ideal Applications 

• Microcontroller Interfacing: Driving 5V/12V components from a 3.3V GPIO pin (Arduino/ESP32).

• LED Drivers: Switching indicator lights or small LED segments.

• Audio Pre-amps: Boosting low-level audio signals for further processing.

• Signal Inverters: Creating NOT gates and other basic logic circuits.

• Sensor Buffering: Interfacing high-impedance sensors with low-impedance loads.