In the last couple of months I have gone all grain, started using liquid yeasts, and built a fermentation fridge - the next step seemed to be a stir plate to help in the re-use of these expensive but lovely yeasts.
It was a piece of p155 so thought I'd share some photos with you for inspiration.
I had an old food steamer lying around (£0.00), which is pretty much exactly the right size for a demijohn!
I took the bottom off it, removed the heating element and fitted a 120 mm fan (£1.74 delivered ebay #310970865538). I then routed some new wires where I had taken the old ones out.
In the middle of the fan, a lump of blutack and two stacks of 5 x 2 mm x 10 mm rare earth magnets (£2.99 delivered, ebay #201078261575).
A bit of playing around with the stirrer bar (£10.95 for two, ebay #111317047460) to get the correct orientation of the magnet. As the bar was 20 mm putting the magnets side by side was the only/correct option. I raised it up with some blutac feet and got something like this:
The reflective strip on the blade is so that I could put my tachometer onto it and confirm that the magnets were not interfering with the fan operation - had to raise them a bit. Played around with supply voltages and got a nice 1000 rpm at 9V.
Popped the cover on:
Did some testing with water, adjusted the feet a little, and then the real thing, seems to be working!
I must say though that the uneven bottom of demijohns is not ideal for this, the bar falls off now and again. It certainly worked well when I could keep it on though. I see a lot of people using 1L flasks - do you not get foam everywhere with these little things!? A 5L flask would be ideal...
Finally - anyone want to give me a fiver for my spare stirrer bar!?
Cheers
Jambo
