Unfortunately, the lack of documentation thing strikes again... It was pretty simple electronically - an ATTiny25, a coin cell, and an LED wired across two IO p

Unfortunately, the lack of documentation thing strikes again... It was pretty simple electronically - an ATTiny25, a coin cell, and an LED wired across two IO pins, for light sensing using LED's junction capacitance as a photocurrent integrator (http://www.merl.com/publications/docs/TR2003-35.pdf http://www.merl.com/publications/docs/TR2003-35.pdf). The trick was in the control algorithm - I got things synchronizing reasonably well, but LED ensemble was prone to all sorts of weird chaotic behavior. I suppose I should recreate it, on an even larger scale. I just need to figure out some better way to power it...