If I wanted to do a fan installation in my player, but didn't care if it was thermistor controlled, could I make it very simple? For instance, like this:

Fan_pin----Variable_resistor-----Fan-----Ground

Then I could use the variable resistor to set the desired fan speed and it would just run quietly whenever the player was on. There's no voltage regulator or anything in this design.

Anyone see a problem with doing it that way?