So I'm thinking of building my own stir plate and was curious if anyone else had given this a try. The wisdom of the Internet (http://www.homebrewtalk.com/f51/my-stirplate-cheap-easy-build-86252/) seems to show that you can do this with equipment that is as simple as a getting an old computer fan, taking the magnets out of an old hard drive, and using a potentiometer to control the speed.
I have an extra programmable controller (Arduino) at home that I was thinking of using to PWM the fan and get a little bit better control of the speed, but I haven't done this stuff in several years, so its probably overkill. Has anyone ever given this a try or have any thoughts?
Lucas,
I did the build from that thread. I used the project box, potentiometer, and switch from radio shack, along with a hard drive magnet and a computer fan that I had lying around. The take-home message I got from my build are that gluing a washer to the fan (and then letting the magnet stick to the washer) is genius. This makes it much easier you get your magnet--and stir bar--completely centered on the fan's axis. However, getting the fan to be the exact correct height below the cover of the project box is an exercise in frustration. I also found that I needed a 92mm fan for my stirplate to be powerful enough to pull a vortex in a full 2L starter. 80mm fans worked, but the ones that I had were not super-powerful and couldn't even pull a small vortex in a 2L starter. I'm sure that a 80mm Delta fan would be fine, if you've got one of those screamers lying around.
Regarding PWM of your fan, I guess that depends on whether you've got PWM-compatible fans lying around. I have a couple, but they're 120mm, and won't fit in the project box from the hbt thread that you linked.
Let me know if you have any questions that I didn't answer.
-Adam