ok... so a while back I posted that I had ordered those Delta 1212AFC server fans. Tried controlling them with an LED dimmer... annoying whine. Got interested in PWM control, and then... hmm 4 pin fan.. get realy PWM control. I didn't know how, so I found a post where people were talking about doing it on overclockers forum.
Long story short - a friend helped to build an awesome controller board. I got frustrated trying to make it work properly. Gave up for a while, ordered something else which didn't work for the fans. Gave me motivation to get it worked out.
Behold the stir monster!
stirmonster01.jpg
5L being stirred - turns out that straight walled is harder to stir than conical and that glass is easier for the stirbar to stay steady on (no surprise).
stirmonster02.jpg
There was a post that said faster stirring was better...
stirmonster03.jpg
I can't get the large stirbar to go quite fast enough to do this, but with a 1" one the stirbar gets completely enveloped in air. I was scared the stirbar would launch off and break the glass the first few times... but it slows down pretty quickly when it gets launched (the little one can go all the way to 4000rpm... )
So why do you need a big stirplate? - big starter of course!
stirmonster04.jpg
stirmonster06.jpg
stirmonster07.jpg
Hard to tell how far the vortex goes down. Not that far. The stirbar is kind of noisy in the bottom of the 20L handypail.
Next step... stir a fermenting beer for the first two days?
edited: clarity