Homebrew Fan Speed Controller

Posted on Feb 6, 2014

A fan speed controller for your computer fans. There are two sections: one for manual speed control, and one for automatic (temperature dependent) speed control. There is also a third section for a simple LED output indicator. Why not just run the fans off the motherboard fan connectors This is what most people should do. However, there are fans out there such as the Vantec

Homebrew Fan Speed Controller
Click here to download the full size of the above Circuit.

Tornado which require more current than the motherboard will supply. This requires an external controller to vary the speed. Some people just want the extra knobs to turn. Why not just buy a fan controller and plug-n-play That is what most people should do. This article is for those who like to tinker and play and burn themselves with soldering irons. It is nice to end up with a working project that you can point to and say "I built that". These projects assume that the reader is somewhat familiar with electronics and has the ability to build circuits from scratch. My projects were built with parts and materials on hand, your available parts and materials may vary. Breadboarding and testing the circuits before soldering is strongly advised. In case you don`t know what I`m talking about, here is a pic of the automatic speed control circuit breadboarded and under test on the bench: Always bench-test the finished project before installing it in your computer to make sure it works and works like it is supposed to. Use whatever construction method suits you best. These projects worked out well for me using a mix of wire-wrap and point-to-point on perfboard. Do not assume that the way I went about these circuits is the only or best way, there are other ways to accomplish the same thing (please post and discuss The simplest approach is to manually adjust the speed by turning a knob. This circuit uses a potentiometer to vary the...

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