Another brewing post! I'm getting ready to brew some more beer and cider and I figured I may as well make one of those fancy yeast stirrers everybody uses. I actually made one of these back in high school but ended up salvaging it for the magnets, one of which ended up being used for retention in a knife sheath. I noticed I happened to have everything I needed to make another one so I cobbled this together. I used a dremel to cut out part of a fan blade so that I could have the magnets directly opposite each other and thus have the assembly balanced. I set them in place with Gorilla glue. For the power supply I used an old cell phone charger (actually the one I salvaged a microUSB tip from for the solar charger in my other blog post).
I used a metal lid from a Pierre Cardin box as the enclosure, or
rather... a cover, since it's just sitting there. I haven't mounted the
fan inside it yet, and I need to figure out the spacing before I do. It seems the magnets are too close to the stir bar. When the stir bar is further above the magnets, it spins fine, but when it is lower such as when it sits on the metal box, it can start to wobble and rattle. I think I might add in a thermoelectric plate on the
top to add hotplate functionality. I also need a better power supply, this
cell phone charger doesn't seem strong enough, and definitely won't be
enough for the TEC.
It would be cool to drill out holes for a speed and heat control knob. It also might be cool to put a heatsink on the inside of the box, under the TEC and over the magnets/fan. Perhaps the TEC could be run in reverse for a... coldplate(?) effect. If the bottom can transfer enough heat through the box and off the heatsink by the fan so that it doesn't overheat, maybe the top can pull heat adequately from beakers holding exothermic reactions above it. But probably not. There's probably a reason nobody else does that. I'll just stick with an old fashioned ice bath for now.
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