2N3904 Transistor

The 2N3904 is a widely used NPN bipolar junction transistor (BJT). It is designed for low-power, general-purpose applications, making it suitable for switching and amplifying circuits. This transistor is particularly popular due to its affordability, availability, and reliability in various electronic projects.

General Information

Type: NPN Bipolar Junction Transistor
Application: General-purpose, switching, and amplification
Packaging: TO-92

Key Features

Low power consumption
High-speed switching capability
Compact size
Wide range of applications in analog and digital circuits

Specifications

Parameter	Symbol	Value
Maximum Collector-Emitter Voltage	V_CEO	40 V
Maximum Collector-Base Voltage	V_CBO	60 V
Maximum Emitter-Base Voltage	V_EBO	6 V
Maximum Collector Current	I_C	200 mA
Power Dissipation	P_tot	625 mW
Transition Frequency	f_T	300 MHz
DC Current Gain (h_FE)	h_FE	100–300

Pin Configuration

The 2N3904 transistor has three pins, which are arranged as follows in the TO-92 package:

Pin 1: Emitter
Pin 2: Base
Pin 3: Collector

Applications

The 2N3904 is used in a variety of circuits and applications, including:

Signal amplification
Low-power switching
Oscillator circuits
LED drivers
Analog circuits
RF circuits

Circuit Example

Simple LED Driver Circuit A 2N3904 can be used to drive an LED:

Connect the emitter to the ground.
Connect the collector to one terminal of the LED with a suitable current-limiting resistor in series.
Apply a small current to the base via a resistor to turn the LED on.

Advantages

Low cost and widely available
High speed for switching
Adequate performance for most general-purpose applications

Limitations

Limited to low-power applications
Not suitable for high-current or high-voltage circuits

Common Alternatives

Other similar transistors include:

2N2222
BC547
BC548

2N3904 Transistor

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