Here I show you how to make a mixer for test tubes. It is pretty easy and you can build it in less than 10 min.

Step 1: Get a E-Motor and Magnets

Almost every e-motor will work but I prefer this tiny ones out of a CD/DVD driver. They work at 1.5 Volts and the rotation speed is not to high. The magnet I use on the shaft of the Motor is also demounted from a CD/DVD-driver (you can find 2 of them close to the lens).

Step 2: Attach the Parts

First superglue one magnet to the shaft of the motor. Do not glue shaft to the housing else it won´t work anymore.

Secondly mount the motor to the bottom side of the rack. I used hot glue. The magnet should be close to a test tube hole. If you have a different looking rack then you have to find a place near a tube and fix it there.

Step 3: Conect Battery

This is a easy step. Just connect the wires to a 1.5 Volts battery the polarity do not matter.
You can also put a switch into the circuit but it is your choice.

Step 4: Put a Magnet Into the Tube

Put a magnet in the tube you are about to use. I used a, 1cm (~0.4inch) in diameter and 1mm (0.04 inch) thick, neodym magnet. But you can also use the one out of the CD/DVD driver.
Do not use bigger and stronger magnets or the glass will crack.
What about solutions harmful to the magnets, won't that have some effect on the chemistry in the tube?
I'll second that. Always read up on what you're mixing and be sure there are no hazardous interactions before you start mixing anything.<br />
You can buy small magnets coated in teflon and various non-reactive plastics.
It's Neodymium (Nd), not Neodym.&nbsp; You can buy ball bearingsized/shaped neodymium magnets online which might mix things better andbe less likely to scratch the test tubes.<br />
any problems with the test tube breaking?? too strong of magnets?..(yes I'm very optimistic....mostly) thanks
where do you buy your glasswear?
You can get glassware and stuff like that at United Nuclear.
Nowhere! I use the one out of a kids-chemical-lab.
lol, but the one in your 'ible was glass (or so you said in step 4. What kind of kids set is it, I've never seen a set with real glass, allways just plastic?
Wow that's simple! Good job.
This is a neat idea.<br/>It's worth pointing out that this is a scaled-down version of a standard piece of lab equipment: <a rel="nofollow" href="http://www.sciencelab.com/page/S/PVAR/21761/50-HI180">The magnetic stirrer.</a> Fancier versions have variable speed, timers, and heaters, and cost big bucks...<br/>
Cool. Do you have a problem catching the magnet when you're pouring the solution out?
That one's easy- you hold another magnet against the base or side to retain the magnet.
I just take another magnet and because of the magnetic attraction they stick together at the bottom. After that you can easily pouring the solution out.
Makes sense.
Never knew it was this easy. Nice job. And the ink in water looks really cool!

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