2N3904 Transistor (NPN, 40V, 200mA)

Description

The 2N3904 is a commonly used NPN transistor, ideal for low-power amplification and switching applications. It is frequently used in various general-purpose electronic circuits due to its small size, low cost, and reliability.

Key Features of 2N3904 Transistor (NPN, 40V, 200mA):

1. Type:
   • The 2N3904 is an NPN transistor, meaning it has a positive-negative-positive (PNP) structure, and current flows from the collector to the emitter when a positive voltage is applied to the base relative to the emitter.
2. Voltage Rating:
   • The collector-emitter voltage (Vce) is rated at 40V, meaning the transistor can safely handle voltages up to 40V between the collector and emitter without breaking down.
3. Current Rating:
   • The collector current (Ic) is rated at 200mA, which means the transistor can safely handle a maximum current of 200mA through the collector.
4. Power Dissipation:
   • The maximum power dissipation is typically 500mW (0.5W), which means the transistor can dissipate up to 500 milliwatts of power before the risk of overheating or damage arises.
5. Frequency Response:
   • The transition frequency (ft) of the 2N3904 is typically around 250MHz, making it suitable for high-frequency applications, such as radio frequency (RF) circuits and high-speed switching.
6. Package Type:
   • The 2N3904 is commonly available in a TO-92 package, a small three-lead package used for low-power electronic applications.
7. Gain (hFE):
   • The DC current gain (hFE) typically ranges from 100 to 300, depending on the specific operating conditions. This value indicates how much the transistor will amplify the input signal applied to the base.
8. Base-Emitter Voltage (Vbe):
   • The Vbe is typically around 0.7V when the transistor is in active mode, which is standard for silicon-based transistors.

Applications of 2N3904 Transistor (NPN, 40V, 200mA):

1. Switching Circuits:
   • The 2N3904 is widely used in switching applications, such as turning devices on and off. It can be used to control low-power devices like LEDs, relays, and motors in switching circuits.
2. Amplification Circuits:
   • It is commonly used in small-signal amplification applications such as audio amplifiers, signal buffers, and oscillators. It is suitable for applications requiring moderate gain for small-signal processing.
3. Signal Processing:
   • The 2N3904 is often used in signal amplification in audio, RF, or digital signal processing applications where low to moderate power is required.
4. Current Regulation and Limiting:
   • The transistor can be used in current regulation circuits where it controls the current flowing through a load, such as limiting the current to an LED or other components.
5. Oscillators and Pulse Generators:
   • It can be used in oscillator circuits to generate specific frequencies in low-power devices. Its high transition frequency (250 MHz) makes it suitable for high-speed switching in low-power frequency generation.
6. Digital Logic Circuits:
   • The 2N3904 is widely used in digital logic circuits for switching and amplification of signals, especially in low-voltage and low-current logic circuits.
7. Signal Isolation and Level Shifting:
   • The 2N3904 is used to provide signal isolation and level shifting between different sections of a circuit, especially when interfacing different voltage levels in digital systems.

Advantages of 2N3904 Transistor (NPN, 40V, 200mA):

1. Small Size (TO-92 Package):
   • The 2N3904 comes in a compact TO-92 package, making it ideal for applications where space is limited and small components are needed.
2. Low Cost:
   • The 2N3904 is inexpensive, making it an attractive option for low-cost electronic circuits and mass production applications.
3. High Gain:
   • With a current gain (hFE) ranging from 100 to 300, the 2N3904 is suitable for small-signal amplification, providing sufficient gain for many applications.
4. Fast Switching Speed:
   • The transistor has a high transition frequency (ft) of 250 MHz, making it suitable for high-speed switching applications and RF circuits.
5. Good Reliability:
   • The 2N3904 is known for its reliable performance in general-purpose applications, including low-power and signal-processing circuits.
6. Wide Availability:
   • The 2N3904 is commonly used and widely available from numerous component suppliers, making it easy to source for a variety of electronic designs.