Anthony_Lopez
Well-Known Member
That pin is for ground, but it is not really needed in this circuit.
Well I tried this out and after several days still am unable to get it working. I managed to get everything on the list at the start from RS and a 12v fan, 9v charger and 2 of the curved HD rare earth magnets. After getting the wiring set up so the fan works, is adjustable and the power is operable I decided to give it a go. The washer I used was the biggest they had at 1.5".
Using two magnets in an "S" pattern or one on each rim of the washer would not spin the bar. This was the case regardless of how far I moved the flask away from the fan or speed. Also, even if the plastic lid was between the fan and flask the bar would not spin.
One of the magnets broke now too so that is scrap. I am not sure where to go from here. Ideas anyone?
What is the size of your stir bar? Try one magnet, put the bar on the magnet to find where it lines up and center at that point:
It is a 2 inch stir bar.
Any thoughts on my power supply questions above?
- 9 Volt battery makes the fan want to fly off the table and the two chargers I have tried won't do anything.
- Will a 10ohm potentiometer work or does it have to be a 25ohm?
- Is it better to have the potentiometer wired to increase power or decrease power
Thanks all, I am hoping to get this figured out in time for a starter this week.
What size potentiometer do you use on your AC fan? I think I have an AC fan laying around but I know that it will go way to fast with out a control dial. Thanks
I struggled with this biuld for 5 days!!!
...
I guess the moral of the story is that the HD magnets are too strong, or, are too close together when used whole (either a strength or interference problem). Of course, I will need to fine tune a bit once I do my first starter sicne this was only done with water, but I feel confident that everything will work as expected.
One final note: the flask that I "borrowed" from work does nto have a perfectly flat bottom...it is a little convex (but not as much as a drinking glass). This of course in not ideal and I still had good results. However, I think I will go "shopping" for one with a flat bottom.
Thank you for posting this how-to and I can now pick up my clumps of hair off of thr floor and glue them back to my head. :cross:
John
finally got this working. I had to turn the screws around and get the magnet as close to the top of the enclosure as possible. ...
johnodon I had the same issue when designing my stirplate and it was finally resolved by increasing the space between the face of the hard drive magnet and the top of the box that the flask sits on. I actually hot glued a 6 inch long piece of 1 x 3/4 pine to the box lid and then hot glued the fan to the piece of wood and this did the trick.I tried every combination of 1, 2, 3 and 4 magnets and 1.5v thru 12v. Either the fan would not turn or the stirbar would get thrown. It wasn't until I broke a single magnet in half that I had any success.
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