Hi i am trying to make a magnetic stirrer. I have seen tutorials on how to make a magnetic stirrer from a pc fan and magnets. i have actually constructed such a device, but the results I got were less than satisfactory. My problem is that the flea used to stir the solution doesn't want to spin. For some reason it keeps switching directions and makes a whole lot of noise, but doesn't spin continuously. Does any one have any suggestions on how to fix the problem or maybe a whole new design.