I constructed a stirrer box and I have some problems.
Here are the parts
-25 amps rheostat
-12V, .012 amps computer fan
-3” nuts + bolts
-One 1-inch stirrer rod (flat)
-Two earth magnets
I wired all the parts together, and the RPMs of the fan were too high even in the zero position. The stirring rod was not spinning, just trembling all over the place.
I made some calculations and found that, for a 12V PSU, 12V/0.12 amps fan, I need a 140 ohms rheostat.
I found another 5V PSU and the rheostat resistance requirement turned out to be zero.
I re-wired the stirrer with the new PSU and still and I have the same problem even though the RPMs were decreased significantly.
Any help will be appreciated.