The magnetic stirrer I bought from PDD broke after only half an hour of use—the charging port had come unsoldered, and upon disassembly I found that the soft-pack lithium battery inside was even swollen. Fortunately, the seller proactively issued a full refund, which is truly commendable.

After properly disposing of the soft-pack battery as hazardous waste, I took it apart and discovered that, in addition to the battery, there was also a charging board (likely outputting 3.3 V), an RC300 DC motor, and two magnets. I happened to have a Type-C dongle and a PWM speed controller left over from a previous project, so I quickly cobbled together a plug-in version. Powered by 5 V, the maximum rotational speed is much higher than before, and I’ve added the ability to adjust the speed.

This is the magnetic stirrer I bought from PDD.

Of course, not everyone is so lucky; here are all the components you’ll need:

1. RC300 DC motor (if you’re worried the standard wiring isn’t long enough, buy one with terminals and extend the wire using a matching female terminal—soldering enthusiasts can simply solder on a longer wire).

2. Type-C dongle

3. PWM speed controller

4. Wiring

5. N52 magnets, 6 mm in diameter and 2 mm thick (I used ones I’d dismantled; this size should be sufficient).

6. Magnetic rotor

Extra tip:

If you’re working with the same model of magnetic stirrer, the wiring is usually long enough—simply remove the MX1.25 terminals from the motor and connect the wires to the PWM speed controller. If the wiring isn’t long enough, purchase a matching MX1.25 female connector and extend the wire accordingly.

The RC300 motor with terminals may also use PH2.0 connectors; the difference in size is quite obvious, or you can measure the spacing to confirm. In that case, purchase a matching female connector and extend the wire.

Installation instructions:

1. Connect the wires as shown in the diagram, placing the speed controller in the indicated position. Be sure to thread the nut that secures the speed controller onto the controller itself. Set the dongle’s DIP switch to 5 V (details can be found on the product page or by contacting customer service). Attach the magnets to the assembly, making sure they’re oriented with opposite poles facing up—one N pole and one S pole—and then secure them to the motor (if they feel loose, apply some glue).

2. Place the Type-C dongle.

3. Install the DC motor. You can use hot melt glue or sponge tape to secure the components, though it’s not strictly necessary—I didn’t use any adhesive, and the parts stayed firmly in place.

4. Finally, secure the base plate with three M2 self-tapping screws, attach the printed handle to the speed controller, and you’re done.