Having some fun with old hard disks…. by taking them apart of course 🙂 Pics here.
There’s some interesting parts inside. Some fantastically strong magnets and an air core coil are used to position the heads. Stepper motors are long gone from hard drives! Might try some wireless charging experiments with the coil.
The platters themselves are spun by a type of 3 phase motor. Connected this up to a spare speed controller (ESC) from a model aircraft. Was able to spin it right up to 15,000 rpm using the aircraft remote control. Checked the speed with the trusty laser tachometer. That’s 250 revs per second, or 1 rev every 4 milliseconds. Makes a great sound at full speed.
Now to figure out some use for such a tiny high speed motor. Gyroscopic effects are very evident at such high speeds too. Maybe make some self balancing widget!