[TriEmbed] Coffee roaster

[Brian]

Oh, and on this point:

> I already have a IRF510N MOSFET. Can I use that instead of a IRF540N?

Looking at DigiKey's parametric search, it seems at a glance that the 
primary difference between an IRF510 and an IRF540N is Source-Drain 
current limitations (the Instructables author incorrectly refers to the 
MOSFET's connections with BJT terminology).  The 510 in a TO-220 case 
handles about 5 A, while the 540N in the same case handles 33 A.  One 
would have to make measurements of the fan motor to determine the actual 
current it will draw, to decide whether the 510 is a suitable part. 
Inductive loads like motors tend to have large inrush currents, so you'd 
probably do well to err on the side of over-spec'ing the part, since 
it's being used to chop DC for PWM (meaning higher average current 
through the motor).

Cheers!
-Brian