So here was my big problem (I say was, but it still isn't working out right) I made my stirplate. I used a 12V fan from radioshack and the large project enclosure. I used 9/16 x 1/4" Neodymium magnets from Cynmar. I added a second potentiometer to "give me some fine tuning". Now I have it so that I can keep a slow spin going, with everything cranked all the way down on a 5.9V power supply. But I can't get that slow spin started. It seems that my magnets are restricting the flow of the fan at slower speeds. I can't deal with it today, I"ve been cursing magnetism for the better part of two hours (magnets + epoxy + confined space + fat fingers = HULK MAD!!!)
So now that I have to pry my magnets off and go buy some more epoxy, can anyone suggest a good insulator that I can attach between the fan and the magnets? How tall should it be? If I make it a bit heavier that should slow down the fan speed right? I'm too frustrated to think too hard about it right now....
I think I am going to use a 2" hole saw to cut a circle out of a 1/2" piece of plywood and epoxy that to the fan hub with the magnets attached to that. It seems like an easy solution....
Terapin, part of the issue might be that most fans will simply not start at low voltage. I think most fans are rated to spin up at 7-9V, but will spin as low as 5V once started. So before you rip your setup apart, see if you can follow the advice given here: start it at a high voltage, and then reduce to an appropriate speed. Cuz you may just be making a lot of effort for nothing.
Yep, I think it's a voltage thang. Start on high, and back down (more juice to 'start' spinning than to 'keep' spinning). Also, 5.9V is just barely enough. There should be no need for a two pots (unless you're running a 9V or 12V PS). Having a second pot in line is another point of resistance, potentially limiting the voltage you have which already the bare minimum. Might try just one.
Yep, mine won't start on low speed either. It took a while for me to get mine going, but it got going. I kept throwing the bar even after I got it going for a while, then I got it set right. My problem is the mason jars I use, I need a flat bottomed vessel next time.
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For me, I turn up the speed all the way up with the power off and the flask in place. Then I flip the power switch, and almost at the same time turn down the speed. Worked great for me this morning for my first time real use:
So as you know, I've been having problems. It seems that no matter what I set up my fan seems to be running at full speed or staggering to a stop. So after trying various power sources and potentiometer set ups I look at the specs that came with my RadioShack fan. It seems that on my fan, "Voltage Range 10.2-13.8V DC" . Now not knowing much about electricity, I would assume that this means my fan will only operate above 10.2V (thus spinning my fan WAY too fast for me to control it?) Do I just need to replace my fan?
Hulk Mad (stirplate magnet question)
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