These custom-made-for-Solarbotics coils measure 20.7mm (0.813″) in diameter, 1.5mm (0.06″) thick, and have a measured inductance of 1.03 millihenries (not microhenries – hence the “Major Henry” designation!) with about 11 ohms resistance. These coils give a substantial kick when powered by a solarengine in a magnetic field, so much so that we’ve had to reduce the size of the capacitors in our Magbot SunDancer kits from 4700µF to 3300µF just so that they don’t knock themselves off their stand.

These coils are the key ingredient in the Zendulum Kit and the Solar Pendulum from Make Magazine Vol. 28, we even carry it in a bundle conveniently packaged for you.