All research areas, be it physics or chemistry or biology, will require at some point in time a stirrer and or a hot plate or a stirrer hot plate combo. These things are quite expensive even when they are barebones devices. If you want one that has PID temperature control, than tack on an extra order of magnitude to the cost of the barebones device if it is sourced from a scientific supply company.

DIYBio has become a big thing lately. Especially with builds like the Pearl Gel Box which literally costs a fraction of what a "scientific" labeled unit would cost. Having access to cheap and easily assembled devices to do garage science really does enhance the whole science community in my opinion. One reason why I think garage science is a good thing is that most people in the hacker space that do garage science like to communicate about what they have done, hence the need for a site like Instructables. Open communication is crucial for science to progress as I am a firm believer that progress is dictated by communication. And, if progress is to succeed, communication must be open. So, thanks to all those that participate in tinkering and are willing to share those endeavors. Scientists could learn something from the community at Instructables.

This build is cheap, easy and voids lots of warranties. With that said, do be careful with this build.

The video of this in action is not embedding properly so a link to it is here.

Update 02-02-2011: Attempting to embed the video again. If you can't see it, use the link above.

Step 1: Tools and Materials

1x Modified Computer Power Supply
1x Electric Griddle
1x Computer Fan  - Hopefully salvaged from the same computer you got the power supply from.
1x DC Motor Controller
1x Rare Earth Magnets
1x Stir Bar
Beakers and the like to do your science in.
2x Banana plugs - Any color. I'm partial to the Emerson / Johnson brand.
4x Banana jacks - Any color. Again, I like the Emerson / Johnson brand.
4x Spacers
4x 4-40 Screws
2x Banana Cables - Any color.
1x Epoxy
1x Solder

1x Soldering Iron
1x Wire Stripper
1x Diagonal Cutters
1x #1 Phillips Head Screwdriver
<p>If you're trying to save money, the PWM is probably not necessary. An apporpriate potentiometer will do the trick. Here's a good video explaining the difference: http://youtu.be/90g6RpvXBYY</p>
<p>I have a question - I used a two-wire fan with the DC motor controller. It turns on, but it only has two speeds - on and off. How would I modify it to make it have variable speed, and did yours have variable speed?</p>
what if you just needed the hot plate?
if you didn't want to use the stirring action, then you don't have to turn the fan on under the plate.
the third wire is for the temperature sensor, with a common ground with the fan
What third wire, if I may ask? Fans don't have a temperature sensor - three-wire fans *do* have a rotation sensor on the third pin. It requires a pullup though.
Ha! That's awesome! I never knew that. Thanks ever so much for letting me know. I will definitely use this in the future for other projects.

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More by amaloney:DIY Laser Shutter DIY Stirrer/Hot Plate Another computer power supply mod 
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