Do you know why this project named as “Mini Lighthouse LED circuit”? It’s because the LED circuit has a shape like a lighthouse and that’s the reason it got the name here!
Basically, this is a simple “lighthouse” that when it’s powered up, it will rotate the beam around the 12 LEDs. This Mini Lighthouse LED Circuit is a very useful tool, especially for a model railway.
For your information, this Lighthouse has several interesting features. The first feature is a full size ICSP connector, while the second is a socketed DIP version of the PIC12F683.
Those 12LEDs is the maximum numbers of you can charlieplex from four tri-state pins. The PIC12F683 is an eight pin device that has five GPIO plus the MCLR pin, where it can be used as an input. You can keep one GPIO spare, GPIO four where it also happens to be an analog port that allow you to add a light sensor that turns the lighthouse on when it gets dark.
Furthermore, this version has an LM317 regulator on the back so it can be driven from 12V or whatever.