The 2N3904 transistor is a dependable NPN bipolar junction transistor (BJT). People use it in many electronic circuits. Engineers and hobbyists like this part for small power jobs. It works well for amplifying signals and turning things on or off. The 2N3904 datasheet lists features that make it well-liked. It can handle a collector current of 200mA. It has a power dissipation of 625mW. Its transition frequency is high at 300 MHz.
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Key advantages from the datasheet:
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It can handle up to 40V between collector and emitter.
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It stays stable in many different temperatures.
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It gives a fair amount of current gain and has low saturation voltage.
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This bipolar junction transistor is used in many projects. It works well, stays steady, and is easy to find. It comes in a small TO-92 package.
Key Takeaways
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The 2N3904 is a popular NPN transistor used for switching and amplifying signals in many electronic projects.
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It has three pins in the order Emitter, Base, and Collector (EBC) that must be connected correctly for the transistor to work.
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This transistor can handle up to 40 volts and 200 milliamps, making it suitable for small loads like LEDs and relays.
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The 2N3904 works fast with a high frequency of 300 MHz and offers good current gain to boost weak signals.
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You can replace the 2N3904 with similar transistors like the BC547 or 2N2222A, but always check the pin layout and ratings first.
2N3904 Transistor Overview
What is the 2N3904?
The 2N3904 transistor is an NPN type. It is a bipolar junction transistor, or BJT. People use it for simple power jobs like amplifying and switching. Motorola made this transistor in the 1960s. It became popular because it is small and works well. The 2N3904 comes in a TO-92 package. It can handle up to 200mA of collector current. It also works with up to 40V between collector and emitter. This transistor can get rid of up to 625mW of power as heat. It has a high transition frequency of 300 MHz. This means it can work in fast and radio circuits. Its DC current gain is between 100 and 300. This makes it good for making signals stronger. The saturation voltage is low, about 0.2V at 10mA. This helps save power and keeps it cool. The 2N3904 can work in hot places, up to 150°C. It is reliable in many different places. There is a PNP version called 2N3906. It works with the 2N3904 in special amplifier circuits.
Note: The 2N3904 is useful and works well. It is often found in school kits and beginner labs.
Common Applications
The 2N3904 transistor is used in many ways. Its main jobs are to make signals stronger and to switch things on and off. Engineers use this BJT in audio amplifiers. It helps make weak sounds louder in radios and speakers. The transistor is also used in LED flashers and pulse generators. It helps control voltage in some circuits. In small computers, it turns devices on and off to save power. The 2N3904 can switch very fast. This makes it good for RF circuits, oscillators, and timers. It is a good switch in digital logic circuits. It controls power for other parts. The transistor makes little noise and gives good voltage gain. This helps sound systems work better. Many smart lights use the 2N3904 to save energy and respond quickly. In schools, students use this BJT to learn about circuits and how transistors work.
Common Uses Table
| Application Type | Example Uses |
|---|---|
| Signal Amplification | Audio amplifiers, radios |
| Switching Applications | LED drivers, relay control |
| RF and High-Speed Tasks | Oscillators, timers, RF amplifiers |
| Digital Circuits | Logic switches, current mirrors |
| Educational Projects | Beginner kits, lab experiments |
2N3904 Datasheet Pinout
Pin Configuration
The 2n3904 transistor comes in a small TO-92 package. This package is used for many tiny electronic parts. If you hold the flat side facing you and the pins point down, you will see the pins in a certain order. The first pin on the left is the Emitter. The middle pin is the Base. The right pin is the Collector. This order is called EBC. The 2n3904 datasheet shows this is the usual layout. The datasheet also says the emitter pin has an arrow symbol in circuit pictures. This arrow helps people find the emitter fast.
Tip: Always look at the 2n3904 datasheet before you connect the transistor. Some companies might use a different pin order, but most use EBC.
A simple table can help you know the pins:
| Pin Number | Pin Name | Location (Flat Side Facing You, Leads Down) |
|---|---|---|
| 1 | Emitter | Left |
| 2 | Base | Middle |
| 3 | Collector | Right |
The EBC pinout is needed for the transistor to work right. The base pin is used to control the transistor. The emitter pin often goes to ground in npn circuits. The collector pin connects to the load or to power.
Pin Functions
Each pin on the 2n3904 transistor has its own job. The datasheet tells what each pin does. The emitter lets current leave the transistor. In an npn bjt, this pin is usually the negative or reference side. The base is the control pin. A little current at the base lets a bigger current move from collector to emitter. The collector gets current from the circuit and sends it through the transistor.
| Pin Number | Pin Name | Description | Polarity |
|---|---|---|---|
| 1 | Emitter | Current leaves the transistor from this pin. | Negative or reference terminal for npn bjt |
| 2 | Base | Control pin; a small current here changes the current in the bjt. | Positive terminal for npn bjt |
| 3 | Collector | Current enters the transistor at this pin. | Positive terminal for npn bjt |
The 2n3904 datasheet lists important things like collector-emitter saturation voltage (Vce(sat)) and current gain (hFE). These numbers depend on using the Emitter-Base-Collector pins the right way. The datasheet says the base current should be about one-tenth of the collector current to turn the transistor on all the way. This matches the normal EBC pin order. The On Semiconductor datasheet also shows how the gain changes with different voltages, which proves the pin layout matters.
People often connect the emitter to ground in switching circuits. The base needs a resistor to keep the current safe, just like the datasheet says. The collector goes to the load, like an LED or relay. This setup lets the 2n3904 work as a switch or amplifier in many circuits.
Note: Always use the right pin order when you build circuits. If you connect the pins wrong, the transistor can break or the circuit will not work.
Key Specifications
Electrical Ratings
The 2N3904 datasheet gives important electrical details. These numbers help people know how the transistor works in real life. The 2N3904 is an npn BJT. It can handle up to 40V between collector and emitter. The highest collector current is 200mA. The datasheet also says the collector-base voltage can go up to 60V. The base-emitter voltage can reach 6V. Power dissipation is up to 625mW. This means it can safely get rid of this much heat. The transition frequency is 300 MHz. This makes it good for fast and RF circuits. The current gain, called hFE, is between 100 and 300 at 10mA. These numbers show the 2N3904 can make signals stronger and switch loads well.
Here is a table that shows the main specifications from the 2N3904 datasheet:
| Parameter | 2N3904 Specification |
|---|---|
| Maximum Collector Current (IC) | 200 mA |
| Maximum Collector-Emitter Voltage (VCEO) | 40 V |
| Collector-Base Voltage (VCBO) | 60 V |
| Base-Emitter Voltage (VEBO) | 6 V |
| Power Dissipation | 625 mW |
| Transition Frequency (fT) | 300 MHz |
| DC Current Gain (hFE) | 100 to 300 |
The 2N3904 datasheet gives these ratings as normal values. Most datasheets do not show test results, but these numbers are trusted. The power dissipation and transition frequency show it works well in low-power and fast circuits. These electrical details make the 2N3904 a good pick for many projects.
Note: Always check the voltage and current gain before using the transistor in a new circuit. This helps keep the transistor safe and makes sure the circuit works right.
Features
The 2N3904 is special because of its features. It is fast, uses little power, and is tough. The transition frequency of 300 MHz lets it switch quickly. This makes it great for RF, audio, and digital circuits. The high current gain means it can make weak signals stronger with little input. The base-emitter saturation voltage is low, between 0.65V and 0.95V. This helps save energy. The highest collector-emitter voltage is 40V. This lets it work in many low-voltage circuits. The highest collector current is 200mA. This means it can run small loads without getting too hot.
The 2N3904 also makes little noise. Low base spreading resistance and low collector-base capacitance help keep noise down. This makes it good for sensitive amplifiers and fast switching. The BJT design keeps it working well in many temperatures. The datasheet says it can work up to 150°C. This means the 2N3904 can last in hard places.
Key features include:
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High transition frequency (300 MHz) for quick switching
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High current gain (100 to 300) for strong signal boost
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Low power use (625 mW) for saving energy
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Low noise for clear signal boost
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Wide voltage range for many uses
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Tough BJT build for lasting use
These key details and features make the 2N3904 a top choice for engineers and students. The datasheet gives all the facts needed to use the transistor safely and well.
2N3904 Equivalents
Equivalent Transistors
Sometimes, engineers need a different part if the 2N3904 is missing. Some transistors have similar features and can be used instead. Here are some common choices:
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BC547: This part is close to the 2N3904 in voltage and gain. People use it a lot in sound and low-frequency projects.
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2N2222A: This one can handle more current. It is good for switching and making signals stronger.
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2SC1815: This Japanese transistor has similar gain and voltage.
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2N4401: People use this one for switching and many other jobs.
The table below shows how the 2N3904 and BC547 are alike and different:
| Parameter | 2N3904 | BC547 |
|---|---|---|
| Pin Configuration | Emitter-Base-Collector (EBC) | Collector-Base-Emitter (CBE) |
| Maximum Collector Current | 200mA | 150mA |
| Maximum Collector-Emitter Voltage (Vceo) | 40V | 45V |
| Current Gain (hFE) | 100–300 | 110–800 |
| Frequency Response (fT) | 300 MHz | 300 MHz |
| Power Dissipation | 625 mW | 500 mW |
| Typical Applications | RF, switching, amplification | Audio, low-frequency |
It is important to check the pin order before swapping parts. The BC547 has a different pin layout. If you mix up the pins, the circuit might not work.
Substitution Tips
To swap safely, match the main numbers like voltage, current, and gain. Always check if the new part can handle the same or more. If it does, it should work in most cases. People often use the 2N2222A and 2N4401 instead of the 2N3904. Many say these swaps work well if the pinout is right.
The 2N3904 works with the 2N3906 in push-pull circuits. The 2N3904 is NPN and the 2N3906 is PNP. Together, they let current flow both ways. This helps amplifiers sound better and makes motor drivers more efficient. Using both gives even signal control, which is needed in sound and analog circuits.
Tip: Always check the datasheet for pin layout and ratings before swapping any part. This helps stop damage and keeps things working well.
2N3904 Uses
The 2n3904 transistor is used in many circuits. Engineers and students use it for switching and making signals stronger. It works for both easy and hard projects.
Switching Circuits
The 2n3904 transistor is often used as a switch. It can turn things on or off by letting current flow or stopping it. This is helpful in digital logic circuits, relay drivers, and LED drivers. The collector-emitter saturation voltage is low, about 0.2V at 10mA. This means it does not waste much power or get too hot. The highest collector current is 200mA, but most people use less to keep it safe. The 2n3904 works well in cold and hot places, from -55°C to +150°C.
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Some common ways to use it as a switch are:
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Digital logic circuits
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Relay coil drivers in automation
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LED drivers in lighting
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Tip: In a simple LED driver, a resistor sends a small current to the base. The collector connects to the LED, and the emitter goes to ground. When the base gets a signal, the transistor turns on and lights up the LED.
Amplifier Circuits
The 2n3904 transistor is also good for making signals stronger. It can boost weak sounds in audio, radio, and voltage amplifier circuits. Its current gain is between 100 and 300, so it can make small signals bigger. In a common-emitter setup, it gives strong signal boost and good voltage gain. People use this in audio amplifiers, RF amplifiers, and small speaker drivers.
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Some typical amplifier uses are:
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Audio amplifiers for radios and speakers
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RF amplifiers in communication devices
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Voltage amplifiers in sensor circuits
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A simple audio amplifier uses the 2n3904 to make a microphone louder. The base connects to the microphone with a coupling capacitor. The collector goes to the speaker, and the emitter goes to ground.
Other Applications
The 2n3904 transistor is used in many other ways. Its high transition frequency and steady work make it good for oscillators, timers, and sensor circuits. Engineers use it in RC oscillators, multivibrators, and voltage regulators. Its small TO-92 package fits well in small designs.
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Other ways to use it include:
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Oscillators for clock signals
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Timers in toys and alarms
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Sensor circuits for temperature and light
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Note: The 2n3904 is useful and reliable. It works well in both home and factory electronics.
The 2N3904 transistor is good for both switching and making signals stronger. The datasheet shows it works well in many ways:
| Parameter | Typical Value | Description |
|---|---|---|
| Voltage (VCEO) | 40V | Can handle medium voltages |
| Current (Ic max) | 200mA | Can power different loads |
| Power Dissipation | 625mW | Gets rid of heat in small circuits |
| Gain (hFE) | 100–300 | Makes weak signals stronger |
| Frequency (fT) | 300MHz | Works in fast circuits |
Knowing these facts helps people use the 2N3904 the right way.
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Try making a simple amplifier or switch with it.
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Look at more datasheets from other companies to learn more.
FAQ
What is the maximum voltage the 2N3904 can handle?
The 2N3904 can handle up to 40 volts between its collector and emitter. This value comes from the datasheet. Users should not exceed this voltage to avoid damaging the transistor.
Can the 2N3904 replace a BC547 in a circuit?
Yes, the 2N3904 can often replace a BC547. Users must check the pinout and electrical ratings first. The BC547 has a different pin layout, so careful wiring is important.
How much current can flow through the 2N3904?
The maximum collector current for the 2N3904 is 200mA. This value allows the transistor to drive small loads like LEDs, relays, or small motors.
What does the EBC pinout mean?
EBC stands for Emitter, Base, and Collector. These are the three pins on the 2N3904. The correct order is important for the transistor to work. The datasheet shows the EBC layout for the TO-92 package.
Is the 2N3904 suitable for audio amplifier circuits?
Yes, the 2N3904 works well in audio amplifiers. It provides good current gain and low noise. Many engineers use it in radios, speakers, and other sound projects.
Written by Jack from AIChipLink.
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