Author Topic: Magnetic Stirrer RPMs  (Read 1715 times)

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Aragorn7

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Magnetic Stirrer RPMs
« on: January 12, 2015, 02:56:20 PM »
What rpm setting would you recommend from a magnetic stirrer for IS/Colloidal Silver production? I read from one site that it should be as low as 20 to 30rpm. This seemed way too slow to me.

Offline kephra

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Re: Magnetic Stirrer RPMs
« Reply #1 on: January 12, 2015, 03:06:29 PM »
Let er rip.  I run mine fast enough to make a vortex almost to the bottom of the flask.  The idea is to produce non-laminar flow (turbulence) around the anode.  This provides maximum scrubbing of the silver oxide.
Colloidal Silver is only a bargain if you make it yourself.

Aragorn7

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Re: Magnetic Stirrer RPMs
« Reply #2 on: January 12, 2015, 03:14:50 PM »
Thanks. That's helpful to know.

sv3nster

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Re: Magnetic Stirrer RPMs
« Reply #3 on: January 18, 2015, 02:48:56 PM »
Build your own. You can do it for about $30, even less if you have spare parts sitting around. Mine has an aluminum top (non-ferrous) and is able to easily stir several liters of fluid. I used it the other day to mix two quarts of elderberry syrup with honey! The stir bar pictured below is 1.5" long. I'll post a how two once I get the finishing touches done internally.


Offline kephra

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Re: Magnetic Stirrer RPMs
« Reply #4 on: January 18, 2015, 02:55:23 PM »
Nice!  Post the plans if you want.
Colloidal Silver is only a bargain if you make it yourself.

Offline Gene

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Re: Magnetic Stirrer RPMs
« Reply #5 on: January 18, 2015, 05:50:40 PM »
A 12VDC computer fan from an old PC or something else being tossed, 2 neodymium magnets glued across from each other near the rim of the hub the fan blade is attached to, in even a cigar box works wonderfully.  Power it from a 12VDC wall cube (don't go higher - these things don't like being abused much).

If you want a speed control search the web as there are already designs to do this which are simple (very few parts).  Home beer brewing enthusiasts apparently grow their own yeast beyond the first batch so they don't have to keep buying the expensive pre-packaged yeast and they need a magnetic stirrer to do it and most go the computer fan magnetic stirrer route as its quite inexpensive and easy to build where several of them have documented their designs and put that information up on the web.

One thing though. These fans all kind of stall around 5-6V on the low end so whatever you'd use for a speed control will only have the fan moving above this output voltage up to full bore at 12V.

You want the thing in a sealed box as that creates enough static pressure that it seriously reduces drag on the blades and the thing will spin faster.  You don't need to go breaking the blades off the hub as some suggest.