Crutschow, sounds like we were both working along the same lines. I'd actualy logged on today to upload a circuit but the one provided by alec_t is a lovely bit of work! Well done alec_t.
Of course this could easily be put into a processor - but i think this circuit it a great way for M-ron to get hands on with the electronics. It should be a nice and easy project to attempt - keep us updated and we'll give you all the info / advice you need to get this thing working.