Not exactly schematics, but [Duckman] has some Arduino pinout diagrams he made using ASCII-art. These could be useful when pasted into source code as comments, documenting the pinouts for your ...

For those starting out in Arduino, there are tons of resources to get better acquainted with the community and the types of projects you can tinker with.

After all, the Arduino isn’t actually measuring the CPU speed, nor is it directly controlling it (that’s still done by the original Turbo button wiring).