Recently I had the problem some expensive components did overheat in my server rack. The ventilation was not optimal and I had to install additional fans. Because this rack is in my office and I like a quiet working place, the ventilation had to be as quiet as possible.
First I thought about buying a off-the-shelf product, but then I realised: If this controller does not work as I expect and the fans will spin too fast/loud, this will drive me crazy over time. So I decided to build a own fan controller. A very simple one, where I can write own code and tweak it until it runs as I like.
On the project page I describe how to build this particular controller. It is not meant you really reproduce this same controller exactly as shown, but maybe understand some basic principles to build your own controller.