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Transistor 2N3904 – Pinout and Specifications

Transistor 2N3904 – Pinout and Specifications

In this post we learn the main specifications and pinout details of the NPN transistor 2N3904


The transistor 2N3904 comes under the category of NPN small signal, low power, general purpose transistor, mainly applicable for switching and for signal amplification.

It's dynamic range may include a current handling capability of more than 100mA for switching applications and a 100MHz frequency handling capacity fits with amplification purposes.

The absolute maximum ratings of this transistor may be understood from the following data:

  1. The Vceo or the maximum tolerable Collector-Emitter voltage is 4 volts.
  2. The Vcbo or the maximum tolerable voltage across collector-base is 60 volts.
  3. The maximum allowable collector to emitter or the Ic must not exceed 200mA.

Other Useful Characteristics of this device are discussed below:

  1. Maximum collector to emitter breakdown voltage for a 2N3904 transistor is 40 volts.
  2. Similarly the maximum collector to base breakdown voltage is 60 volts.
  3. The maximum base to emitter breakdown voltage is 6 volts.
  4. Minimum current required for keeping the base of the transistor activated is 50nA.
  5. Similarly the minimum amount of current required to keep the collector load switched is also 50nA
  6. The hFE or the forward current gain of the device is between 100 to 300.
  7. The minimum amount of voltage required for activating the collector is 0.2 volts, its also known as the collector-emitter saturation voltage.
  8. The minimum amount of voltage required to trigger the base of the device is 0.65 volts, its also called the case/emitter saturation voltage.
  9. The above data is quite sufficient and adequate for any electronic hobbyist for understanding the transistor 2N3904 safely and correctly.

The pin outs of the transistor 2N3904 are given in the following diagram.


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I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!

2 thoughts on “Transistor 2N3904 – Pinout and Specifications”

  1. Dear Swagatam
    I have read several of your transistor tutorials. Can your please explain all above in a complete detailed tutorial. For instance what are the above parameters, what they mean, where to use them and why? So far where ever I have read about transistors, they seems complicated or just incomplete in a sense that one site defines one thing and other sites defines some other parameters. A complete tutorial of a transistor so a newbe e can understand and utilize all important features of a transistor designing circuit himself, is yet to be seen.

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