2N2904 Pinout, Equivalent, Application, Datasheet

The 2N2904 pinout defines the lead configuration of this high-performance PNP bipolar junction transistor (BJT), designed primarily for general-purpose switching and low-frequency amplification. This transistor is known for its robust current handling capability, low leakage characteristics, and excellent linear performance. With its reliable thermal behavior and consistent gain across temperatures, the 2N2904 transistor is widely used in small-signal amplifiers, driver stages, and low-power switching circuits.

Introduction to 2N2904 PNP Transistor

The 2N2904 transistor is a PNP silicon BJT housed in a TO-39 metal can package, offering moderate power dissipation and durability. It is built to handle medium current levels and operate efficiently in audio, signal processing, and analog driver circuits. The 2N2904’s sturdy design and low noise characteristics make it suitable for high-fidelity audio amplifiers and industrial control systems.

Due to its stable electrical characteristics, it is often used alongside its complementary NPN transistor 2N2218, creating balanced push-pull amplifier configurations.

2N2904 PNP Transistor

Pinout of 2N2904

Pin Configuration of 2N2904 Pinout

Key Features of 2N2904 Transistor

• Reliable and thermally stable PNP transistor
• Low collector leakage and consistent DC gain
• Strong linear response for signal amplification
• Durable TO-39 metal package for better heat dissipation
• Suitable for audio and analog driver stages
• Good switching performance in medium-power circuits

2N2904 Transistor Datasheet and Specifications

• Collector-Emitter Voltage (Vce): –40 V
• Collector-Base Voltage (Vcb): –60 V
• Collector Current (Ic): –600 mA
• Total Power Dissipation (Ptot): 400 mW
• DC Current Gain (hFE): 100 (typical)
• Transition Frequency (fT): 200 MHz (typical)
• Junction Temperature (Tj max): 200 °C
• Package Type: TO-39 Metal Can
• Polarity: PNP
• Pin Configuration: Emitter–Base–Collector (E–B–C)

Equivalent and Alternative Transistors

The following are equivalent or alternative transistors that can replace the 2N2904 in most circuits:

• 2N2905
• 2N4033
• PN2905
• MPS2907
• BC558 (for lower current)
• 2N2907A

Always confirm voltage and pinout compatibility before substitution.

More Circuit Layouts

Applications of 2N2904 Transistor

• Audio amplifier stages
• Driver circuits and relay controls
• Analog signal amplifiers
• Voltage regulator circuits
• Switching and inverter designs
• Biasing and feedback control networks

Understanding the 2N2904 Pinout Configuration

The 2N2904 pinout follows a standard Emitter–Base–Collector (E–B–C) arrangement when viewed from the bottom (leads downward). This configuration makes it easy to integrate into TO-39 compatible sockets or directly solder into amplifier circuits without confusion.

Working Principle of 2N2904 Transistor

The 2N2904 PNP transistor operates by allowing current to flow from the emitter to the collector when a small base current is applied in the opposite direction. In this configuration, it acts as a controlled current amplifier or switch. When the base voltage is lower than the emitter voltage, the transistor becomes active and allows larger collector current flow.

Its stable gain, quick switching response, and ability to handle moderate current make it ideal for driver amplifiers, signal conditioning, and relay control applications.

Comparison Summary — 2N2904 vs 2N2905

• The 2N2905 is a close equivalent to the 2N2904, sharing similar voltage and current ratings. However, the 2N2904 has a slightly lower power dissipation capability (400mW vs. 600mW) and may be used in more compact low-power applications. Both transistors maintain excellent thermal stability and similar gain performance, with the TO-39 case ensuring solid heat transfer in analog circuits.

Frequently Asked Questions (FAQ)

What is the 2N2904 transistor used for?

It’s mainly used for signal amplification, switching circuits, and driver amplifier stages in analog designs.

What type of transistor is 2N2904?

The 2N2904 is a PNP bipolar junction transistor (BJT) designed for low to medium-power applications.

What is the pin configuration of 2N2904?

It follows the Emitter–Base–Collector (E–B–C) pin sequence when viewed from the bottom.

Can 2N2904 replace 2N2905?

Yes, in most cases. The 2N2904 can replace the 2N2905, especially in low-power or lower voltage designs.

What package type does the 2N2904 use?

It is housed in a TO-39 metal can package, ideal for improved heat dissipation and reliability.

Conclusion

The 2N2904 transistor is a reliable and efficient PNP silicon BJT designed for use in a wide range of analog and low-power switching applications. With moderate voltage and current ratings, low leakage, and stable amplification characteristics, it remains a solid choice for designers seeking consistent performance in compact amplifier and driver stages.

Its availability, versatility, and dependable TO-39 construction make it a preferred choice for classic and modern circuit designs alike.

Datasheet & Pinout of 2N2904 PNP Transistor

Click the following Button to download the datasheet of 2N2904 Transistor :

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