I built this to test some “color washing” ideas I had, but it didn’t turn out like a hoped. In my mad rush to get it done (or maybe it was the post 1am state of mind), I wired it up backward… I was shootin for common anode, that is each led shares a common voltage supply and is controlled via their ground connection… but what I built is common cathode. Each led shares a common ground connection and is controlled by the supply.

Why is that bad? Well… If you’re going to use digital logic to control things, the easiest way is with a MOSFET transistor … the cheap and common N-Channel mosfets deal with low-side or ground connection … so with all the leds sharing the same ground, I cannot controll them independently.