Choosing the right NPN Transistor

Using Arduino General Electronics
10

"How to choose the right transistor for controlling object A (which uses more current) through a GPIO (which can give less current).

As you have likely read, the in general most folks find an MosFet a more desirable choice than a BJT (transistor). Why....

  • A Mosfet can mimic a switch to ground with lower voltage across it when on than a transistor.
  • A Mosfet takes nearly no current to control, where as a transistor used as a switch required ~ 1/10 of the current being controlled to be provided from the µP output pin.

So to answer your question, you start with the requirements:

  1. how much current do you wish to control. This will help chose a specific part.
  2. are you trying to switch to ground or to +V
  3. If trying to switch to +V, is the voltage you are trying to control higher than the arduino voltage?