I'm trying to build a CoffeeBot from MAKE magazine, and I had a question about one of the components. The circuit is pretty simple; it uses an Arduino to control a gear motor via a MOSFET transistor. The Arduino is using a digital pin which I believe is capable of PWM, but in the code provided it merely turns ON/OFF.
So my question is about the MOSFET. I understand the basics of transistors, but why this particular part? The part listed is a 12N10L Logic Level MOSFET. What makes a MOSFET in this instance better than a regular NPN transistor? Is it the current that it can handle? Or is it somehow better at high frequency switching, were I to use PWM to control speed?
Also, if it is the current/heat capabilities of the part that makes it ideal for this job, what advantages would it have over something like a TIP31 or a TIP120 transistor?
Edit: People have rightly noted that I forgot an important detail, the current required by the motor. This is a small gear motor GM8 that seems to stall out at 400mA. Does that change the issues with the TIP120?