* I spent more than $7, but you can save money by just following what I did.
My brewing has evolved to needing a yeast starter. The option to buy a stir plate was out of the question. Its not that I couldn't afford one. I'm just cheap. I'm also an avid DIY'r so it seemed like a simple project I could get done fairly quickly. I researched lots and liked the idea of using a computer fan, magnets, stir bar, etc. I settled on a radioshack build buying the parts needed including a retrostat (potentialometer?) and on/off swtich. Being handy, I had most of the other stuff lying around. A quick Ebay search netted me TWO 12v computer fans for $3! The 1" stir bar was $2, and a set of round rare earth magnets was $2 at a local craft store.
I got frustrated trying to get this thing to work in an old wooden cigar box. The pull was not strong enough, the spin bar would not spin, etc. I couldn't mount the fan to the box-it was either too far, or too close. The box was driving me nuts. Then it occurred to me, why use the box? The box was limiting my potential! Get rid of the box!!
I screw mounted the computer fan to piece of wood. I set a piece of 5x7 picture frame glass on top of the fan. The screw heads created just the right amount of clearance to allow the fan to spin.
I used strong adhesive to glue the magnets directly to the fan hub once I determined + and - polarity and made sure my stir bar was attracted to it.
With the picture frame glass in place, I set my flask on top, dropped the stirbar in, it drew to the polarity of the magnets and it started to spin once plugged in.
I may or may no attach the retrostat/potentiometer-but it seems to work without it and total cost of just these items was $7!
My brewing has evolved to needing a yeast starter. The option to buy a stir plate was out of the question. Its not that I couldn't afford one. I'm just cheap. I'm also an avid DIY'r so it seemed like a simple project I could get done fairly quickly. I researched lots and liked the idea of using a computer fan, magnets, stir bar, etc. I settled on a radioshack build buying the parts needed including a retrostat (potentialometer?) and on/off swtich. Being handy, I had most of the other stuff lying around. A quick Ebay search netted me TWO 12v computer fans for $3! The 1" stir bar was $2, and a set of round rare earth magnets was $2 at a local craft store.
I got frustrated trying to get this thing to work in an old wooden cigar box. The pull was not strong enough, the spin bar would not spin, etc. I couldn't mount the fan to the box-it was either too far, or too close. The box was driving me nuts. Then it occurred to me, why use the box? The box was limiting my potential! Get rid of the box!!
I screw mounted the computer fan to piece of wood. I set a piece of 5x7 picture frame glass on top of the fan. The screw heads created just the right amount of clearance to allow the fan to spin.
I used strong adhesive to glue the magnets directly to the fan hub once I determined + and - polarity and made sure my stir bar was attracted to it.
With the picture frame glass in place, I set my flask on top, dropped the stirbar in, it drew to the polarity of the magnets and it started to spin once plugged in.
I may or may no attach the retrostat/potentiometer-but it seems to work without it and total cost of just these items was $7!
