I needed a magnetic stirrer to keep some cells agitated for cell culture, but didn't want to spend the thirty or so dollars needed to buy one. This magnetic stirrer uses an old computer fan and some cheap neodymium magnets with a moldable plastic stir bar.
The parts are:
- computer fan
- small magnets: http://www.dealextreme.com/p/super-strong-rare-earth-re-magnets-8mm-20-pack-4248 (free shipping)
- moldable plastic (polymorph, instamorph, shapelock)
Step 1: Glue the Magnets to the Fan
Prepare and clean the fan for use. Your fan may have two wires (red for positive and black for negative). If it has three wires, the white wire is a tachometer and is not needed. Glue the magnets on opposite sides of the fan head. The magnets in the fan's motor may push the magnets around a bit, so arrange accordingly. I arranged the magnets to have opposite polarities facing up.