Homemade Magnetic Stir Plate <$20

Chris Norrick · Post by **Chris Norrick** » Sat Feb 18, 2006 11:28 pm

Made a magnetic stir plate today for yeast starters for less than $20. Got the idea after listening to one of The Brewer's Network radio shows. It uses a computer fan and hard drive magnet and a dimmer switch used for ceiling fans. I used mostly parts I had laying around which kept the cost down. CLICK HERE if interested in pics and details.

Justin Rumbach · Post by **Justin Rumbach** » Sun Feb 19, 2006 11:35 am

Your are one handy mofo Chris! So how does the magnetic stir plate actually work to increase yeast production?

Chris Norrick · Post by **Chris Norrick** » Sun Feb 19, 2006 4:37 pm

Here's a quote from the Norther Brewer Yeast Page: "Magnetic stir plates drastically increase cell count and activity in a yeast starter. The constant motion keeps yeast cells in constant contact with oxygen, nutrients, and food."

I used the regular size Wyeast smack pac. Popped it Thursday morning, made the yeast starter Saturday morning. Finished the stir plate Saturday night and started using it then. I don't know if that delay will affect results. I'll hopefully be pitching Monday afternoon and will be able to judge effectiveness then. I've made a few starters with this size smack pac so I have a rough idea how much yeast I get without the stir plate. The guy on the radio show also makes another starter the morning of brewing and pitches the old starter into it to get the yeast really going. He claims that he has active fermentation in 2 hours or less. He actually likes to get bubbles in 1 hour. That may be a little crazy, but the scottish ale I'm doing tomorrow is supposed to be fermented really cool, so I figure the more yeast the better.

The garage/brewery was REALLY cool this morning! Think I'll go ahead and keg the pale ale as all the yeast have settled out.

Chris Norrick · Post by **Chris Norrick** » Mon Feb 20, 2006 10:14 pm

Well, I definitely had tons of yeast but I think I shocked them a little bit. The recipe calls for 55 F fermentation. The yeast have been growing in 78 F so I don't think they liked it very much when I poured them into the 55 degree fermenter. So far no signs of fermentation after 5 hours... I imaged this thing just taking off like mad crazy. There is about 1/2 inch of yeast all over the bottom of the fermenter.

Kenny Lucas · Post by **Kenny Lucas** » Mon Feb 20, 2006 11:02 pm

Hey, the stir plate looks like a great idea. I almost caught one on
the Bay for about 30 dollars, but as usual, lost it in the last seconds to what I'm sure was a non brewing loser. If you get a chance, bring it to Wednesday's meeting.

For my two cents, I recently purchased the oxygen injector that uses an oxygen cylinder and a filter with a stone on the end. I've had starts in less than 4 hours. I usually pump a little into my starter, and pump the s#*t out of the chilled wort. I actually popped the airlock off of my starter once. If I can incorporate the stir plate into the mix, the yeast will probably just jump in on thier own.

Chris Norrick · Post by **Chris Norrick** » Tue Feb 21, 2006 6:54 pm

They'll crawl right up through the airlock!

I got an O2 tank but my mail order place is having a hard time getting the regulators and stones. I guess their supplier was down in the New Orleans area.

The stir plate is an easy build if you have the parts and can force yourself to go into Radio Shack.