OVHA Chat

Just curious as I have seen a number of these powered by computer muffin fans with magnet followers. Isn't that far too fast? I was thinking in the 30 rpm range?

I put a rheostat (potentiometer) @ 25 Ohm in the circuit that lets me adjust the speed.
I also added an adjustable power supply, 6, 7.5 & 12 vdc. This help me adjust the speed and power when I have a 5 liter Erlenmeyer flask or a 2 liter, heavy slurry or light one.
When I have a large yeast starter for my lagers I will need to turn up the pot to get a little more power.
As of RMP I have no idea, I've never measured.

30 RPM's in a slug slurry may not turn at all.. plus the weight of magnet will slow it down some. It's not going to turn at 2000 RPM's or what ever the fan is rated for.

The best thing you can do is have too much power. EBAY has used lab equipment. Just have to watch for the right one. The ones you build or buy from a brew store are just too limited.

Both of the ones I built, one from an old AC muffin fan, and one from a new, really cheap DC muffin fan can handle 1/2 to 3/4 gallon starters in 1 gallon jugs with no problem. It will pull the vortex to the stir rod. The DC one will throw the stir rod off the magnet at full power but that is mainly due to the fact that the jugs have a convex bottom. A flat bottom flask has no trouble.

Now a surplus HEATED stir plate would be a nice investment! My AC one actually builds up some heat as it runs but the DC does not.

Holy crap, I stand corrected!

Does anyone have any extra foam stoppers for a 2L erlenmeyer flask? I just need one, if you do would you please bring it to the meeting tommorrow and I'll pay ya?

I won't be at the meeting this month. But aluminum foil works great.

I agree with Jimmy, soak a piece of aluminum foil in Star-San and put over the top.

Yea its more for me, I just like things to look neat...

Instead of using starsan on the flask and aluminum foil to sanitize I sterilized it in the oven at 340F for 60mins.. I read that in "How To Brew".. I still used star san on the magnetic stir rod and funnel though. I wasnt sure if the stir rod was oven safe..

I find that when the yeast starter looks like this it is a little fast..

Whats it's look like on high speed?