2N3904 VS 2N3906 Understanding the Difference

Are you looking for 2N3904 VS 2N3906 transistor or the difference between these two transistors? If yes, then you have come to the right place. In this article, we are going to discuss about the difference and similarities between these two transistors such as their pin comparisons, and comparisons of their ratings. Moreover, we will also discuss about what these transistors are and how we can use them and also answer some frequently asked questions about these transistors.


2N3904 VS 2N3906



What is a 2N3904 Transistor?

2N3904 is a very popular NPN BJT transistor designed to use in general purpose switching, amplification and other general applications. Its PNP complementary transistor is 2N3906.

The transistor is available in TO-92, SOT-23 and SOT-223 packages. Looking at the pin configuration of the transistor the first pin of the transistor is “Emitter” second is “Base” and third is “Collector”.

It is a small signal transistor used in variety of commercial and industrial applications. Additionally it is also used in many educational electronic projects too. As it is an NPN transistor so it requires positive input at its base to pass current between its collector and emitter. And to make it fully saturated or fully switch ON we have to provide atleast 0.6V at its base with 15mA to 20mA.


What is a 2N3906 Transistor?

2N3906 is also a very popular PNP transistor which is also designed for general purpose switching, amplification and other general applications and its NPN complementary transistor is 2N3904.

Like 2N3904 this transistor is also available in TO-92, SOT-23 and SOT223 packages. Same as the pin configuration is also same such as the first pin is “Emitter” second is “Base” and the third is “Collector”.

It is also a small signal transistor that is used widely in commercial, industrial and educational circuits. As discussed the 2n3906 is a PNP transistor so it requires negative voltage at its base to pass current between its collector and emitter and to set it on full saturation mode or fully ON we have to provide atleast 0.6V at its base with 15mA to 20mA.


Difference between 2N3904 and 2N3906

The 2N3904 is an NPN transistor and 2N3906 is a PNP, this is a major difference between these two transistors so we cannot replace them directly but it is possible to use the one in the place of other and in most situations it also works. But for doing this one must have some knowledge about how to design a circuit or how the transistors work in electronic circuits.

Ratings & Characteristics 2N39042N3906
Collector-Emitter Voltage (Vceo)40V- 40V
Collector Current (Ic)200mA- 200mA
Total Device Dissipation (PD)625mW 625mW
DC Current Gain (hFE)30 To 30030 To 300
Frequency (fT)300 MHz300 MHz

As you can see at the ratings and characteristics chart above both the transistors have same ratings but the 2N3904 has positive ratings and 2N3906 has negative this difference is because (as mentioned before) both are different type of transistors one is NPN and another is PNP. For further details about what are the difference between NPN and PNP transistor check our page here: NPN VS PNP Transistor.



So finally both the transistors are different type of transistors one is NPN and another is PNP and cannot be replaced directly in a circuit and the user must have some knowledge of electronic circuits if he/she wants to interchange them.



Can I use 2N3904 instead of BC548?

Yes, you can use 2N3904 instead of BC548 and there are also other transistors which you can use instead of BC548 such as BC547, BC549 etc. More details on this can be found on the BC548 page.


Is BC547 same as 2N3904?

BC547 is not almost same as 2N3904 but you can replace them in most applications. But one thing should be kept in mind that the pin configurations of both the transistors are different so it is suggested to check the pin configuration before replacing in your circuit.


Are all 2N3904 the same?

Yes all the 2N3904 transistors are the same but you will find slight differences between different manufacturers. For example, some manufacturers made it with 300MHz transition frequency and some made it with 250MHz.


What does a 2N3904 do?

It is a general purpose NPN BJT transistor that is designed for performing general purpose  small signal tasks in electronic circuits such as switching, amplification, oscillation etc.

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