⚛️ Butterfly Mendocino Motor: the simplest (and very elegant) version of this motor, with only two photovoltaic cells mounted with care to ensure precision balance. This motor will spin quietly to high RPMs on any sunlit windowsill. In this model made by Semyon Nazarov, each of the two photovoltaic solar cells is connected to a coil of copper wire under the opposing solar cell. ⁠ ⁠ When the rotor is lit from above, the top solar cell provides electric current to the coil in the bottom position, which becomes a temporary electromagnet that pushes against the permanent magnet in the base, propelling the rotor to rotate. As the rotor turns, the coil that moves into the bottom position is likewise energized by the solar cell currently at the top. One can say the light commutates this motor. ⁠ ⁠ 2D magnetic levitation is provided by permanent magnets where an acrylic plate constrains the third dimension and makes for a nice bearing surface for minimal friction. Invented in the 1960s by Dary...