matthewstn
New Member
I have been reading on this forum for a while now and not contributing anything, so here is my stir plate. This has been done many times, but if you are like me, you like seeing other people's builds! I didn't take photos of the build process unfortunately, but here it is:
Materials
I started out putting the magnet directly on the computer fan, but the magnet's strong magnetic field interfered with the fan motor's magnetic field and put a lot of drag on the system and burned out the first fan I used. So, I used a gallon jug cap and tape spool as spacers, which helped out a lot. Also I used extra nuts on the machine screws to make the fan height adjustable. The magnet sits about 1mm under the closed lid of the cigar box. The only problem I have now is that even with the pot set at 25 ohms, the stir bar spins a bit too fast and flings off to the side after about 5 minutes of use. Now I'm not an electricity expert, but I plan on wiring a 10 ohm resistor in series right before the pot so I can actually fine tune the fan speed with the pot. Also, I plan on drilling a 2" hole directly under the fan and a 2" hole on each corner to cool the unit (the 12V converter and pot give off heat) and so at night the blue LEDs on the fan show from under the box. If anyone has any suggestions or would like more info, please speak up!
Materials
- Computer fan
- ND hard drive magnet
- 12v 3.5A power supply
- 25 ohm 3W rheostat/potentiometer
- Automotive on/off switch
- Teflon tape spool
- Milk jug cap
- #6 2" machine screws
- 1" stir bar
- Rubber feet for the corners
- Wires, glue, electrical tape, etc
I started out putting the magnet directly on the computer fan, but the magnet's strong magnetic field interfered with the fan motor's magnetic field and put a lot of drag on the system and burned out the first fan I used. So, I used a gallon jug cap and tape spool as spacers, which helped out a lot. Also I used extra nuts on the machine screws to make the fan height adjustable. The magnet sits about 1mm under the closed lid of the cigar box. The only problem I have now is that even with the pot set at 25 ohms, the stir bar spins a bit too fast and flings off to the side after about 5 minutes of use. Now I'm not an electricity expert, but I plan on wiring a 10 ohm resistor in series right before the pot so I can actually fine tune the fan speed with the pot. Also, I plan on drilling a 2" hole directly under the fan and a 2" hole on each corner to cool the unit (the 12V converter and pot give off heat) and so at night the blue LEDs on the fan show from under the box. If anyone has any suggestions or would like more info, please speak up!
