A Proportional 12V Fan Controller

The Ubuntu machine covered in my previous post lives in a cupboard with a wireless router and a DSL modem. Its not a very big cupboard, and… it gets rather warm in there. Even though the computer doesn’t use a lot of power, the heat doesn’t have anywhere much to go. Thats not good for longevity or reliability. I made a couple of 100mm diameter vents of the kind you use to vent clothes dryers, high and low, from the back of the cupboard into an adjacent storage room, but convection just didn’t seem to be doing enough, especially on warm days.

The answer was, of course, to add a fan.