2N3904T93

Introduction

The 2N3904 transistor is a commonly used small-signal NPN transistor. It is part of the bipolar junction transistor (BJT) family and is most commonly used in low power and small signal switching applications. It is made up of three terminals, namely the emitter, collector and base, and two types of doping materials which are of opposite types. The doping materials induce an electric field between the terminals when sufficient current is applied and result in a flow of charge carriers in the resulting field. This makes the transistor function as an amplifier with the varying current to the base controlling the current through it. Production of the 2N3904 transistor is highly automated, making it one of the most cost effective transistors available.

Construction and Working Principle

The 2N3904 transistor is essentially composed of two junction transistors with a common base, with each transistor having an N-doped and P-doped region. A typical 2N3904 transistor may look like a small flat, rectangular object, with three metal legs protruding from it. The two outside legs represent the emitter and collector, while the middle leg is the base of the transistor. The common base of this transistor allows it to act as an amplifier or switch. When a small current is applied to the base, it creates a larger current to flow through the emitter and collector, thus amplifying any weak signals or allowing the transistor to act as a switch.

The working principle of the 2N3904 transistor is based on the principle of junction transistors. When a small current is applied to the base of the transistor, it creates an electric field across the N and P regions, causing charge carriers (mostly electrons) to flow through them. The resulting current is then amplified, depending on the ratio of the collector current to the base current. The gain of the transistor, which is usually in the range of 100–300, is determined by the applied current and the type of doping materials used in the creation of the transistor.

Advantages of the 2N3904 Transistor

• Small size and low cost: The 2N3904 is one of the most cost-effective transistors available in the market. It comes in a very small package and hence is ideal for electronics projects which require a lot of low power switching or amplifying.
• Low distortion: The 2N3904 is known for its low distortion in its amplifying process, which makes it ideal for use in high-fidelity audio amplifiers.
• High power handling capability: The 2N3904 transistor is capable of handling up to 600mW of power, which makes it suitable for a wide range of applications.
• High switching speed: The 2N3904 transistor has a very fast switching speed, which makes it ideal for use in time-critical applications.

Applications of 2N3904 transistor

The 2N3904 transistor is used in a wide variety of applications due to its low cost, small size and high power handling capability. Some of the common applications include:

• Amplifying weak signals from sources such as microphones and audio circuits.
• Switch circuits which require fast switching.
• Timers and oscillators.
• High-gain amplifiers for audio applications.
• DC power supplies.

Conclusion

The 2N3904 transistor is one of the most popular small signal transistors on the market. It is used in a variety of electronic applications due to its low cost, small size and high power handling capability. Understanding its construction and working principle makes it easier to use the transistor in different applications and to understand its performance.