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HomeCommunitySubjectWhat is the difference between them: 2N3904 vs. BC547?

What is the difference between them: 2N3904 vs. BC547?

Transistors - Bipolar (BJT) - Single TRANS NPN 40V 0.2A TO-92 In this article, we will unlock 2N3904 vs. BC547 or the differences between these two transistors.

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Oct 16, 2021

Angelo Butler

Top 3 Projects Using BC547, 2N2222A, 3904 Transistors and LED

 

Transistors - Bipolar (BJT) - Single TRANS NPN 40V 0.2A TO-92

In this article, we will unlock 2N3904 vs. BC547 or the differences between these two transistors. There is a huge range of Semiconductors, Capacitors, Resistors and ICs in stock. Welcome RFQ!

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2N3904 vs. BC547 Overview

It is good to compare two components, which is also a good technique to have a better understanding of a component and to see if it can be replaced with something else. Both the 2N3904 and the BC547 have commonly used transistors that are also well-known among electronic enthusiasts and tinkerers.

Features

2N3904 Features:

  • Bi-Polar NPN Transistor

  • DC Current Gain (hFE) is 300 maximum

  • Continuous Collector current (IC) is 200mA

  • Base- Emitter Voltage (VBE) is 6V

  • Collector-Emitter Voltage (VCE) is 40V

  • Collector-Base Voltage (VCB) is 60V

  • Available in To-92 Package

BC547 Features:

  • Bi-Polar NPN Transistor

  • DC Current Gain (hFE) is 800 maximum

  • Continuous Collector current (IC) is 100mA

  • Emitter Base Voltage (VBE) is 6V

  • Base Current(IB) is 5mA maximum

  • Available in To-92 Package

 

2N3904 vs. BC547 Pinout

2N3904 vs. BC547 Pinout

 

Both transistors are packaged in the TO-92 package, which is a plastics packaging, as shown in the image above. However, when we compare pins, we find that both are distinct in this regard. The first pin on the 2N3904 is Emitter, the second is Base, and the third is Collector, whereas the first pin on the BC547 is Collector, the second is Base, and the third is Emitter.

 

2N3904 vs. BC547 Ratings & Characteristics

Ratings &   Characteristics 2N3904 BC547
Collector-Emitter   Voltage (Vceo) 40V 50V
Collector Current   (Ic) 200mA 100mA
Total Device   Dissipation (PD) 625mW 500mW
DC Current Gain   (hFE) 30 To 300 110 To 800
Frequency (fT) 300 MHz 300 MHz

Can Use 2N3904 Instead of BC547?

Can Use 2N3904 Instead of BC547?

The highest Collector to Emitter Voltage (Vceo) of the 2N3904 is 40V, but the BC547 Vceo is 50V, as shown in the table above. When changing a transistor, the Collector to Emitter voltage is vital to look at, although a difference of 10V isn't a concern unless your load is under 40V. The maximum collector current of the 2N3904 is 200mA, while the collector current of the BC547 is 100mA. The total device dissipation of the 2N3904 is 625mW, while the BC547 is 500mW. This is a little change that will not affect performance. When utilizing a transistor in a high-frequency or RF circuit, its (fT) is taken into account. However, because the (fT) value of 300MHz is quite good, both of these transistors can be employed in RF circuits without difficulty. We can deduce from these details that the 2N3904 transistor can be used instead of the BC547.

 

Can Use BC547 Instead of 2N3904?

The BC547 transistor can be used in place of the 2N3904 transistor, however, there are some conditions that must be met before utilizing it instead of the 2N3904. The collector current differential between the two transistors is the most important factor to consider. Because the collector current of the 2N3904 is 200mA and the collector current of the BC547 is 100mA, you can replace the 2N3904 with BC547 if the load you're driving is less than 100mA, but you can't use BC547 if the load is greater than 100mA.

Conclusion

Because the transistors 2N3904 and BC547 are nearly identical and have few differences, they can be utilized interchangeably in most situations.

However, keep in mind that pin configuration must be maintained because the pinout and collector current of both transistors are different, therefore you must know how much load you are driving in your circuit to replace these transistors with each other.

Frequently Asked Questions

Is there a 2N3904 equivalent transistor?
Any of the substitutes you already mention will work: 2N2222, 2N4401, 2N2907, BC547. Really any general-purpose small-signal transistor will work for this circuit.
What does a BC547 do?
The BC547 is an NPN transistor meaning when power is applied to the base (control pin) it will flow from the collector to the emitter. Typically NPN transistors are used to “switch ground” on a device, meaning, they are placed after the load in a circuit.
What is the equivalent of a BC547 transistor?
BC547 Transistor Equivalent BC547 transistor can be used as an alternative to many transistors: BC548, BC549, BC636, BC639, 2N2222 TO-92, 2N2222 TO-18, 2N2369, 2N3055 and 2N3904 all are BC547 transistor equivalent.
How do you know if a transistor is working?
Hook the positive lead from the multimeter to the BASE (B) of the transistor. Hook the negative meter lead to the EMITTER (E) of the transistor. For a good NPN transistor, the meter should show a voltage drop between 0.45V and 0.9V. If you are testing the PNP transistor, you should see “OL” (Over Limit).
FAQ
Is there a 2N3904 equivalent transistor?
Any of the substitutes you already mention will work: 2N2222, 2N4401, 2N2907, BC547. Really any general-purpose small-signal transistor will work for this circuit.
What does a BC547 do?
The BC547 is an NPN transistor meaning when power is applied to the base (control pin) it will flow from the collector to the emitter. Typically NPN transistors are used to “switch ground” on a device, meaning, they are placed after the load in a circuit.
What is the equivalent of a BC547 transistor?
BC547 Transistor Equivalent BC547 transistor can be used as an alternative to many transistors: BC548, BC549, BC636, BC639, 2N2222 TO-92, 2N2222 TO-18, 2N2369, 2N3055 and 2N3904 all are BC547 transistor equivalent.
How do you know if a transistor is working?
Hook the positive lead from the multimeter to the BASE (B) of the transistor. Hook the negative meter lead to the EMITTER (E) of the transistor. For a good NPN transistor, the meter should show a voltage drop between 0.45V and 0.9V. If you are testing the PNP transistor, you should see “OL” (Over Limit).

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