The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

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  • Magnetic Stirrer: Interior

    Of late, the magnetic stirrer mixing my morning cocoa occasionally doesn’t start spinning when I turn it on, which calls for some investigation.

    Removing the four obvious screws concealed under the rubber feet and prying off bottom cover reveals the trivial innards:

    Magnetic stirrer - interior
    Magnetic stirrer – interior

    The speed adjustment pot holds the little circuit board in place, with the green LED setting its jaunty angle.

    The motor spins a pair of neodymium magnets:

    Magnetic stirrer - magnet holder
    Magnetic stirrer – magnet holder

    I expected a gearbox instead of the direct drive setup.

    Perhaps those whirling neodymium magnets have been slowly demagnetizing the motor’s internal (alnico?) magnets.

    The motor brushes seem to be a pair of stiff wires, rather than carbon blocks, contacting the commutator, the wear from which may account for motor’s decreasing startup enthusiasm. Even though I didn’t expect a BLDC motor, this one may have been overly cheapnified.

    Perhaps kickstarting the motor with the steel fork I use to fish the stirrer magnet out of the mug will get the thing going.