Ever wonder what’s inside those insufferable singing cards? I sure have. Well, I got one a week or so ago from my coworkers, when they took me out to a good-bye lunch. (It plays Smash Mouth’s “All Star”, in case you were wondering, which I guess you probably weren’t.) A few strategic surgical cuts, and voila:
Nothing too surprising, I guess: a speaker, a lithium battery, and a little bit of circuitry with a simple switch at the top. The switch consists of a metal flange which presses against a contact beneath it, normally separated by a little plastic tab. When you open the card, the plastic tab gets pulled out from between the contacts, closing the circuit and activating the awful music.
Now to figure out what to do with a small speaker and a lithium battery.