Anybody knows how those greeting cards with sound work?
I cracked one open the other day (given to me by my wife; wife wasn't too happy but that's a different post) and was amazed to find a really simple circuit, a 3.3V Li battery, RC filter (not SMT)and a loudspeaker.There was a huge black ceramic dot which probably had a memory of some sort with the song in it? There was a switch connected to this black dot. Do those things have a memory + D/A converter to play the song? (I ended up using the 3.3V battery for my projects.)
Another one I got had a feature to record a message which you could open to listen. However, when you closed the card you lost it and had to re-record indicating that there may be some RAM there?