2N3904 VS BC547 Understanding the Difference

In this article we are going to discuss about 2N3904 VS BC547 or the difference between these two transistors. Comparing two components is also an easy way to deeply understand a component more easily and also helps in replacing it with other components. 2N3904 and BC547 both are popular and widely used transistors and also are quite famous in electronic hobbyists and tinkerers, so today we are going further deep into comparing these two transistors and discuss about their ratings, characteristics, features and other useful information.


2N3904 VS BC547



2N3904 VS BC547 Pin Difference

As shown in the image above both the transistors are manufactured in the TO-92 package which is a plastics package. But when we do pin comparison then both are different according to this aspect. The 2N3904’s first pin is Emitter, Second is Base and third is Collector while the BC547’s first pin is Collector second is Base, and third is Emitter.


Ratings & Characteristics Comparison:

Ratings & Characteristics 2N3904BC547
Collector-Emitter Voltage (Vceo)40V50V
Collector Current (Ic)200mA100mA
Total Device Dissipation (PD)625mW 500mW
DC Current Gain (hFE)30 To 300110 To 800
Frequency (fT)300 MHz300 MHz


Can We Use 2N3904 Instead of BC547

As you can see in the above table the maximum Collector to Emitter Voltage (Vceo) of 2N3904 is 40V whereas the BC547 Vceo is 50V. The Collector To Emitter voltage is an important factor to see when replacing a transistor but the difference of 10V is not a problem unless your load is under 40V. The maximum collector current of 2N3904 is 200mA while BC547 has a maximum collector current of 100mA. The total device dissipation of 2N3904 is 625mW and BC547 is 500mW, again it is not a big difference and it will work without any hassle. The (fT) of a transistor is considered when you are using it in a high-frequency or RF circuit. But the 300MHz is quite good (fT) value due to which both of these transistors can be used in RF circuits without any hassle. By looking at these details we can say that 2N3904 transistor can be used instead of BC547.


Can We Use BC547 Instead of 2N3904 

BC547 transistor can also be used in the place of 2N3904 but there are some conditions and you must have to check these before using it instead of 2N3904. The one main thing to consider is the collector current difference between the two transistors. The collector current of 2N3904 is 200mA and BC547 is 100mA therefore if the load you are driving with the 2N3904 is under 100mA then you can replace it with BC547 but if the load is above 100mA then you can not use BC547 instead of 2N3904.



Both the transistors 2N3904 and BC547 are almost the same and there is little difference and hence can be used interchangeably in most cases. But some important things should be kept in mind that pin configuration must be followed because the pinout of both the transistors are different and also the collector current of both are different, therefore you should have the knowledge of how much load you are driving in your circuit to replace these transistors with each other.

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