2N3904 Transistor: Features, Applications and Datasheet

It was Motorola Semiconductor who registered the 2N3906 PNP transistor and the 2N3904 NPN transistor in the mid-1960s. Plastic TO-92 packages are available for these transistors. Due to its low cost and robust design, this transistor can be used primarily by beginners and researchers. Looking at the flat side of this transistor, we see three downward-pointing leads. From left to right, the three wires can be connected to these leads. Some manufacturers marked it EBC (emitter, base, collector). The purpose of this article is to give a brief overview of the working of a 2N3904 NPN transistor.

Overview of 2N3904 Transistor

NPN bipolar transistors (BJTs) such as the 2N3904 can perform well in low-power, low-current, and medium-voltage applications. In switching and amplification circuits, the 2N3904 is known for its versatility. A 300 MHz transition frequency, a maximum collector-emitter voltage of 40V, and a maximum collector-collector current of 200mA make it ideal for use in a variety of electronic devices. For hobbyists, educators, and professionals alike, this device is ideal for signal amplification and switching tasks.

Aside from its reliable performance, the 2N3904 transistor is also easily integrated into a variety of circuits. A TO-92 package makes it easy to install through-hole components on printed circuit boards (PCBs). This component remains a staple in many electronic designs due to its broad availability and low cost. For engineers and enthusiasts alike, the 2N3904 continues to be a go-to transistor for audio amplification, signal processing, or switching digital circuits.

Specifications

There are a variety of electronic applications for the 2N3904 transistor, which is known for its reliability. A detailed description of its capabilities can be found below:

Electrical Characteristics

• Type: NPN Bipolar Junction Transistor (BJT)

• Maximum Collector-Emitter Voltage (VCEO): 40V

• Maximum Collector-Base Voltage (VCBO): 60V

• Maximum Emitter-Base Voltage (VEBO): 6V

• Maximum Collector Current (IC): 200mA

• Maximum Power Dissipation (Ptot): 625mW

• Transition Frequency (fT): 300 MHz

• DC Current Gain (hFE): 100 to 300

Thermal Characteristics

• Maximum Junction Temperature (TJ): 150°C

• Storage Temperature Range: -55°C to +150°C

• Thermal Resistance, Junction to Ambient (RθJA): 200°C/W

Package

• Package Type: TO-92

• Lead Configuration: Through-hole

• Pin Configuration:

• Pin 1: Emitter

• Pin 2: Base

• Pin 3: Collector

Features

NPN Bipolar Junction Transistor (BJT)

In essence, the 2N3904 is a transistor made up of two n-type semiconductor materials separated by a thin layer of p-type semiconductors. By controlling a large current flow between the collector and emitter terminals with a small current at the base terminal, this configuration is suitable for amplification and switching.

Low Power Consumption

In terms of voltage and current specifications, the 2N3904 operates efficiently with low power consumption. For applications that require minimal power consumption, such as portable electronic devices, its collector current is 200mA and its power dissipation is 625mW.

High Transition Frequency

This transistor is capable of operating effectively at high frequencies due to its high transition frequency (fT) of 300 MHz. 2N3904 is suited for RF (radio frequency) applications, signal processing tasks, and high-speed switching.

Wide Range of Voltage Tolerances

VCEO and VCBO of the 2N3904 are rated at 40V and 60V, respectively. Circuits designed with this material can operate at different voltage levels due to its voltage tolerances.

Moderate Current Gain

A moderate level of amplification can be achieved by the 2N3904 due to its DC current gain (hFE) of 100 to 300. Especially useful in applications where stability and noise are not concerns, this feature offers balanced gain without compromising stability.

Compact TO-92 Package

Printed circuit boards (PCBs) can easily handle and install the TO-92 package of the 2N3904 because it is small, plastic, and through-hole. The 2N3904 offers both prototyping and production advantages, as it is commonly used for discrete semiconductors.

Low Saturation Voltage

It operates at an emitter current of 10mA with a collector-emitter saturation voltage of 0.2V. This allows it to operate efficiently, especially in switching applications, with minimal power loss.

Thermal Stability

There is a temperature range of -55°C to +150°C for storage of 2N3904 devices, and a junction temperature of 150°C for the maximum junction temperature (TJ). It is therefore suitable for use in a wide variety of environments thanks to this feature.

Versatile Applications

In addition to signal amplification and switching, the 2N3904 can also be used as a building block in more complex circuits because of its versatile features. Both hobbyists and professionals use it for their electronics projects because of its reliable performance and ease of integration.

Widely Available and Cost-Effective

In educational applications, prototyping, and commercial product development, the 2N3904 is a popular choice due to its availability and cost effectiveness. The low cost of this product makes it ideal for use in large quantities without affecting the project's overall budget.

Applications

Signal Amplification

Audio Amplifiers: Audio amplifier circuits commonly use the 2N3904 transistor to boost low-level audio signals. The device's moderate current gain and reliable performance allow it to reliably boost weak audio input levels into sound levels that can drive speakers or other audio output devices. The 2N3904 is therefore indispensable for radios, microphones, and other audio equipment that needs clear, amplified sound output.

RF Amplifiers: RF applications benefit from the 2N3904's 300 MHz high transition frequency. It improves communication device reception and transmission by amplifying weak RF signals. High-frequency devices, such as radios, wireless communication equipment, and other devices that operate at high frequencies, rely on this capability to maintain signal integrity.

Voltage Amplifiers: The 2N3904 transistor is utilized in amplifier circuits to increase low input voltages to high output voltages. Sensor signals need to be amplified for accurate data processing when they are interfacing with microcontrollers or other digital circuits. Precision amplification can be achieved with the transistor since its balanced gain can be achieved without introducing significant noise.

Switching Applications

Digital Logic Circuits: Using 2N3904 transistors, digital logic circuits operate by regulating current flow according to input signals. Digital components such as logic gates and flip-flops require this capability. Computers, automation systems, and digital electronics are built on the 2N3904, which is used in many circuits.

Relay Drivers: Activating relays in relay driver circuits controls high-power devices by using the 2N3904. Increasing a transistor's base current allows it to switch on or off the relay coil by flowing a larger current. In scenarios involving home automation, industrial automation, or automotive electronics, low-power digital signals are needed to control higher power loads.

LED Drivers: In addition to driving LEDs, the 2N3904 can also be used as a driver. A graphical display, status indicators, and dynamic lighting systems can all benefit from this technique. It provides visual feedback and illumination in a wide range of applications by ensuring LEDs operate efficiently and reliably.

Oscillators and Timers

RC Oscillators: RC oscillators (resistor-capacitor) can be made with the 2N3904 to generate periodic waveforms. For digital circuits, oscillators produce clock signals; for audio applications, tones; for control applications, timing signals. Electronic systems require accurate timing and synchronization, so the transistor's stable performance is crucial.

Multivibrators: The 2N3904 is used in multivibrator circuits to generate square waves. In digital electronics, circuits like this are necessary for controlling pulse width modulation (PWM), generating waveforms, and generating timing signals. These oscillator applications benefit from the 2N3904's rapid and consistent switching ability.

Sensor Interfacing

Temperature Sensors: By amplifying voltage changes related to temperature variations, the 2N3904 interfaces with temperature sensors. Analog-to-digital converters (ADCs) or other monitoring systems can then process this amplified signal accurately. HVAC systems, industrial processes, and consumer electronics use this application to monitor and control temperature.

Light Sensors: It is used to boost all current from a photodiode or light-dependent resistor (LDR) in light-sensing applications. Lights in automatic lighting systems are typically controlled by transistors based on ambient light levels. In homes, offices, and public spaces, the 2N3904 helps to ensure clear, strong light sensor signals.

Wrapping Up

In both amateur and professional electronic projects, the 2N3904 transistor has proven to be a versatile and reliable component. A broad voltage tolerance, low power consumption, and high transition frequency distinguish this device as one of the most versatile and dependable. As a signal amplification, switching, oscillating, and sensor data interface device, the 2N3904 exhibits consistent performance and stability. Due to its compact design, TO-92 continues to be a popular prototyping and production component due to its wide availability and low cost. In general, the 2N3904 continues to provide innovative functionality and drive innovation across a broad range of industries.