I’ve been looking into persistance of vision (POV) style displays recently as part of a new project. The spherical projectors are especially cool and groovy.
What really impressed me about this particular implementation is the use of pulsed 12v DC to drive a circular transformer wrapped around the drive motor. So enough power is being transmitted to the spinner to illuminate all the LEDS. The corresponding web site is in Russian, but you can use Google to translate it.
The corresponding pickup coil rectifies and smooths the power signal back to a stable level, enough to power all the LEDs in the POV. I’m seriously thinking about applying this principle to my Dalek dome – to give it full 360 degree rotation, no slip rings, or extra batteries.