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.
I think that it's good to keep your hand in with some plain old C programming once in a while. So I ocasionally mess around with microprocessors. I've been working on an improved annoyatron, with my version it will pretend to be a mobile phone - by playing a simple ringtone. This is what it currently looks like:
I've used an AVR ATmega168 microprocessor, which is over spec, but I had a couple of them lying around. In fact all of the other components except for the button cell battery and holder were things that I had sitting around. What tends to happen is that before I throw anything away, I take it to bits to see if I can remove anything. Even a salvaged switch can be useful one day. And it's fun to take stuff apart :-)
So ... what I'll try to do is post more about this - what development tools I've used and what I have discovered along the way. I'll be sure to refer back to it if nobody else does.