The Picaxe internal comparator can be configured as an op-amp. See this app note tip #12. Using a comparator this way is not ideal and will probably cause some harmonic distortion, but that's irrelevant with regards to a go/no-go sound detector. Neat huh?
I'm not set up to try this ATM, but probably will eventually. Any takers?
I'm not set up to try this ATM, but probably will eventually. Any takers?