JNewbs
Member
So I made a Cigar box stir plate using commonly available directions. Components:
Wall transformer outputting 12V @ 1000mA
25 Ohm Rheostat (speed control)
Case fan - 1.8 Watts rated power @ 0.15A
I am using a 1.5 inch stir bar - it was octagonal with a ring but I did my best to smooth out the rough spots and I cut off the ring. It isn't perfect but it isn't bad either.
At the lowest speed the stir bar is making quite a tornado:
And after a few minutes it will get thrown at this speed, even. It won't hold at higher speeds at all, even for a few minutes.
What I would like to do is slow down the base spin rate by 50%, or maybe even more. Then I could actually use the rheostat for speed control and not just leave it pegged at minimum. The only problem is that I don't know anything about circuits or the math thereof. I figured if I could solder in some sort of in line resistor, that would do the trick. I'm hoping one of you can tell me how big that resistor has to be, and where I should put it in the circuit:
- Between the wall and the fan
- Between the wall and the rheostat
- Between the rheostat and the fan
Thanks for the help!
Wall transformer outputting 12V @ 1000mA
25 Ohm Rheostat (speed control)
Case fan - 1.8 Watts rated power @ 0.15A
I am using a 1.5 inch stir bar - it was octagonal with a ring but I did my best to smooth out the rough spots and I cut off the ring. It isn't perfect but it isn't bad either.
At the lowest speed the stir bar is making quite a tornado:
And after a few minutes it will get thrown at this speed, even. It won't hold at higher speeds at all, even for a few minutes.
What I would like to do is slow down the base spin rate by 50%, or maybe even more. Then I could actually use the rheostat for speed control and not just leave it pegged at minimum. The only problem is that I don't know anything about circuits or the math thereof. I figured if I could solder in some sort of in line resistor, that would do the trick. I'm hoping one of you can tell me how big that resistor has to be, and where I should put it in the circuit:
- Between the wall and the fan
- Between the wall and the rheostat
- Between the rheostat and the fan
Thanks for the help!