POV stands for "Persistence of Vision"; Poi is the art of spinning weighted and often flaming balls around yourself, and it also refers to the weight-on-a-string itself. We set out to create a poi that would light up LEDs along its length while spinning, to create patterns in the air that persist in the vision of whoever is watching.

The POV circuit uses Charlieplexing to drive up to twenty LEDs from five IO pins of a microcontroller (which means an ATtiny13 can drive it). The LEDs are mounted on a wire, which allows it to be spun like a poi, with the batteries and the circuitboard as the weight.

Here are some pictures of a prototype circuit being waven in front of a camera - unfortunately it's much harder to see with the naked eye:

Here's a video of the poi spinning.