As homebrewer, i need every brew day magnetic stirrer to steer a yeast. Otherway than use spoon. I needed to keep everithing as steril as possible, because contamination and so on... I researched that in chemistry laboratory use magnetic stirrers for almost all agressive chemicals, and that was point of interest. I ve google it for price but there was a lot of quite same products for really big price. I ve google some of DIY project for that, a lot of people make it with a fun from old PC. I ve made it at home from fun. But after a 5 minut of using it, i realize that use fan is just for fun, and i have to make it better. Than I opened my box with an old pcs and printers parts and found some interesting dc motors and brushless motors form CD rom as in video.
It seems to be nice little thin solution, but i didn't have 3 phase driver for motor.
That's why i decide to use DC motor.
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Step 1: Research of Choosed Part
I have one of chinies PWM 1,3-15V 2A, thats why the choosing of DC motor was the best choice.
Motor RS-385SH has 0,2A and 10000 RPM with no load, and that was what i need. It has also chain wheel on the chaft, I used it to carry on neodymum magnet without glue and keep it on axis while rotating.
At work we have a neodymium magnets for whiteboard, and was extremly powerfull strong. I tooks a few and works amazing!
Of course a nice tiny box with minimum IP66, in this solution have to be little bigger than i expect 70mm to height ! But if you use smaller dc or brushless, it could be about 20mm and you could use really nice wooden box.
Step 2: Cost
4,49€ - RS-385SH
3€ - PWM 1,3-15V 2A
1,5€ - box
1€ - neodymium magnet
8€ - TOTAL
(except power 12V 1A supply for aprox. 2€)
Step 3: Think About Catching
When I had a look to a motor, and think about how to, catch it in the box, there was a many options.
1. use heat glue - good but you have to glue your fingers, breath bad smell, really bad vibration proof.
2. use screw - box would not be water tight
3. something much more heavy, vibration proof, strong and easy to remove/clean/repair...
Step 4: Assembleing
3th option was something with full volume of space of box.
I decided to take the 1. piece of wood, mark the center for axis, measure DC motor drill a hole with 0,5 mm tolerance and pressed it in, to fit exact on place and in level i need. And cut it to the exact lenght of inside box. Because it need to be changeable to the future, if something will happen. Thats why i dont want to use any glue or screw. and also for easy assemble.
Step 5: Eppur Si Muove!
It Works, and really well.