Here is my mundane entry. A schematic of my 20-year-old Christmas light chaser, originally designed to safely handle 50 lights per string. It can handle more than that, with proper safety precautions followed and being realistic. This same circuit was later modified to become a name-in-lights project for seven lucky female recipients, all are long since gone their separate ways from me.
The video is on VHS, and cannot be uploaded in time for viewing. The tape is in a remote location, and I haven't attempted to upload video yet.
This is a non-uC entry.