I think the power supply can act as base for the magnetic stirrer project! Let’s combine the two and build a simple magnetic stirrer that looks like a professional one.
Commercial magnetic stirrers are equipped with heater and rotation speed controller for stir bar. I have added PWM speed controller to this project but not the hot plate.
You may like to build a more professional one by adding a hotplate as well to your design.
Step 1: How it works?
Step 2: Open up the power supply and cut extra wires
Multiple output wires are connected to PC power supply to power different PC units. You may use them if you decide to turn the PC power supply to bench top power supply. But in this project we only need the power supply fan to run. Keep green wire, two red wire and three black wires and cut all extra output wires. You can use thermal glue to cover remain part of wires gently. Make sure that stripped wires with diffract color are not in touch after cutting.
Red = 5 Volts
Step 3: Connect a 3w thermal resistor to 5V output
Step 4: Add power on-off switch
Step 5: Add LED power on indicator
Step 6: Attach two small strong magnets to the fan
Step 7: Top plate
Step 8: Immerse magnet bar (stir bar) and run
The next stops are related to the speed controller.
Step 9: Speed Control with PWM
You just need to cut the fan wires and connect them to the output of the speed controller. The input of the speed controller would be the output of the power supply for the fan.
Note that we cannot reduce the fan speed by reducing its voltage. It requires the 12 V to run. That is why by pulse width modulation (PWM) controller, we supply the same 12 V voltages to the fan in on-off manner with high frequency.
Step 10: Install the PWM inside the enclosure
- Add insulator to the back side of the PWM PCB.
- Cut the fan wires and connect them to the output of the PWM controller.
- Connect the input of the PWM to the output of the power supply for the fan
Step 11: Final assemble (The Rabbit and the Turtle)
Print small rabbit and turtle images and attach them to the front panel to show the direction of speed increment. You may come up with other ways to show this like arrows or plus and mines.
Hope you like this project!
Have Fun with your projects!