felis
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DIY magnetic stirrer
Gentlemen,
I recently built a magnetic stirrer mostly from junk which works surprisingly well. Project details and pictures here:
Part 1.
Part 2.
Enjoy,
/felis
/felis
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stateofhack
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Thanks, much of use 
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MJ_
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Nice work!
Reminds me of one I made once from a PC fan, magnet and a potentiometer. Was suprised at how well it worked considering how crude it was.
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Bobross
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Excellent! I'm currently working on a stirrer hotplate, also using an Arduino. I don't think it'll end up being much cheaper than buying a second hand
one once I factor in buying the Arduino board, but I'll be able to use the controller for other projects too. That code you've posted should come in
handy, I'll post a report when it's finished.
I think I'm going to add an LCD display to show the heating and stirring levels, maybe I'll add a temperature control as well.
Thanks for posting.
[Edited on 7-10-2009 by Jhonbus]
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grndpndr
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FUBAR,Sorry,grndpndr
[Edited on 6-11-2009 by grndpndr]
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kmno4
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Topic with the same title exists for a long time:
http://www.sciencemadness.org/talk/viewthread.php?tid=3056
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1281371269
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I just can't get mine to work. I purchased a 40mm diameter neodymium magnet for it, built a case, spliced a phone charger as the power supply, but it
just doesn't work and I have no idea why. With a proper teflon stir bar it doesn't work at all and with nails it sometimes works for a bit then stops.
Is the magnet not strong enough? It's the strongest one I've ever encountered!
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felis
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What exactly stops working? The motor stops spinning? This means your power supply is not strong enough - get a bigger one.
/felis
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watson.fawkes
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Which way is the disk magnetized? Is it North on obverse
and South of reverse, as is typical? Now, what's the net torque on a metal bar lying right above the surface of such a spinning disk?
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1281371269
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Nope it was a half south half north. The motor keeps spinning, the bar doesn't move or spins madly for a bit then stops.
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felis
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You need a pair of magnets glued to a motor with opposite poles facing up.
/felis
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Sedit
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Quote: Originally posted by Mossydie  | | I just can't get mine to work. I purchased a 40mm diameter neodymium magnet for it, built a case, spliced a phone charger as the power supply, but it
just doesn't work and I have no idea why. With a proper teflon stir bar it doesn't work at all and with nails it sometimes works for a bit then stops.
Is the magnet not strong enough? It's the strongest one I've ever encountered! |
Slow down the motor quite a bit and see if it couples with the stir bar. I find with the homemade ones of mine that if the magnet underneath spins to
quickly the stirbar will now keep up correctly yet when I slow it down(used my finger for a break pretty much) it would grab the stirbar and spin
correctly. After that it would pick up and run full speed but sooner or later loose its couple again and just slowly spin. Try running it slower and
see if its the same as the problem I was having.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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1281371269
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I've tried that, it's actually running pretty slowly so it's unlikely that this is the issue. The best bet is probably to try what felis said - I'll
give it a go and if it still throws up problems I'll just buy a proper one.
Thanks for all the advice  .
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