I have been starting to learn to use Eagle, so that I can document my circuit diagrams. Being quite new to designing hardware I'm learning that it's not good enough to just keep a copy of the source code anymore! So, here is the very simple circuit that makes up my improved Annoyatron:
It's very simple to knock this up on a small breadboard, you just need the ATMega168, a speaker and a battery, just like this:
Obviously, the ATmega168 is overspecified, but I have a few of them and it's easier to mess around with one type of processor. I really will try to post the source code and some notes on how to get the source code onto the processor as a program. Honest.