Stir plate too fast

[iceman]

Is it ok to have your starter mixing very fast on a stir plate. I made a stir plate with a computer fan in a cigar box, when i hook it up to a 12v power supply the vortex goes all the way to the bottom and creates a few bubbles. Should i get a smaller power supply or is this ok.

[siwelwerd]

As long as it doesn't throw the bar you're okay. No need to get a smaller power supply if you did want to slow it down, you can wire a resistor in series to accomplish that.

[11amas]

On the other hand, your PC fan will run just fine on a 9v supply so instead of a resister, you could test with a lower power brick and it may be "just right".

[triple-oh-six]

On mine I have 2 rheostats (potentiometers), one couldn't slow it down enough so I installed a 2nd


viewtopic.php?f=4&t=13039&hilit=geek+stir

[a10t2]

If you do use a resistor and/or potentiometer, make sure it can handle the power. (Or use multiple resistors in series.) Most you'll find are rated 1/4 W, and you'll need 1 W minimum.

[mordantly]

i throw a 2" bar >1200rpm in 2L of wort. but i stir from 200-500 depending, but that keeps the vortex <1 inch deep. more doesn't seem to work any better. once i had 2L at 800rpm, when the power came back on, it frothed over and made one hell of a mess for me.

[bsegroves]

A 2" bar might be a good idea for you. My computer fan stirplate won't even turn with a 2" bar but spins very fast with a small bar.

cheers

[11amas]

All you need is a minor surface disruption; a 1" deep vortex is not going to make a difference according to the Pope of malt. So, again, why does everyone use a 12v power brick when the fan will run just fine on 6-9v? A knob looks cool but unless you need to crank up the speed to stir different depths of liquid it seems to be unnecessary complications to me.