jgalak:
KE7GKP:
If this is a fixed installation (a door-bell) then why are you running it from a battery?Because right now I'm still testing various components, and it was easier to hook up a 9V battery to the breadboard. I'm testing things modularily - got the ISD1932 working on one breadboard, the xBee on another, now trying to get the amp to work on a third... This project is a long way from done.
Tried grounding the input to the LM386, no noticeable difference - the hum is still there, exactly the same.
Do you know what the frequency of the hum is? If you knew that, then you could (potentially) design a filter for it; I suspect that likely it is a 50/60 Hz AC from home wiring (or maybe the wall wart you're using, feeding back thru "ground"). Do you have an o-scope? Alternatively, you could try recording the output using your computer then analyzing the recording to determine the frequency (unfortunately, though, you don't know what the signal level is, and you don't just want to feed anything into your sound card, or you could blow it; without an o-scope, this might be tricky to figure out, without a lot of trial and error)...