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**CodeRage** · 09-04-2009, 01:22 AM

I was sitting at work today extremely bored with my current project and had poly phase motors on the brain.

I am not discrediting the fan based stir plate. It is simple and seems to work wel; but, there might be another way to skin this cat.

First of all, does any body have problems with the fan based stirrers? Like thrown stirbars, dust, size, and noise?

I was thinking of maybe setting up a 3 or 4 pole system with 6 or 8 electromagnets arranged in a circle. Then cycle and swap polarities of the poles to spin the stirbar above it. The stir bar becomes the rotor essentially. It does sound like overkill, but there are no moving parts. Which I thought was pretty nifty.

What do you guys think?

**Yuri_Rage** · 09-04-2009, 01:25 AM

I bet it would work really well. The fan solution is cheap but inelegant. Your solution is cheap (or could be), elegant, and perhaps overcomplicated. Maybe that's why I like it!

Buzzy · 09-04-2009, 01:36 AM

HMMMM???? I think you may be on to something. I just finished my fan style stir plate but I haven't made a starter yet. I like your idea.

Drake371 · 09-04-2009, 01:44 AM

would love to see your design.

drake

weirdboy · 09-04-2009, 01:47 AM

The only thing I wonder about is that you'll have to overcome the inertia of the stir bar so I suspect you might have to slowly build up the angular velocity when you start.

Orangevango · 09-04-2009, 01:47 AM

Sounds like the way a particle accelerator works... kinda.

k1v1116 · 09-04-2009, 01:49 AM

I think that is exactly how higher end commercial stirplates work. If you build it I would love to see a circuit diagram.

weirdboy · 09-04-2009, 01:57 AM

I'm sure you could do something pretty straightforward with a 555 timer and a potentiometer.

**CodeRage** · 09-04-2009, 02:12 AM

Quote:

Originally Posted by weirdboy

I'm sure you could do something pretty straightforward with a 555 timer and a potentiometer.

Yeah that could work, would require a bit of discrete logic too though. Im thinking of a cheap PIC with at least 4 Ouputs and an A2D for speed control input. I think the cost difference would be negligible. Push/Pull drivers for each pole and that would be all she wrote.

I am going to goto the craft store tomorrow and look for some thin plastic thread bobbins to hold the windings. Ordered some magnet wire earlier today too.

I just might be able to get the thing to fit into a standard CD case.

Catt22 · 09-04-2009, 02:12 AM

I think it's a brilliant concept and I see no reason why it wouldn't work. I would design it so that you could control both the sequencing speed and the strength of the electromagnets.

I also think you could sell a ton of these if the cost was low enough. The muffin fans work OK, but I think there may well be a better way.