Musical holiday card with a CD case
Dmitry Griberg’s musical holiday card project is really cool and plays a full song in full fidelity from an SD card. The project uses Attiny85 microcontroller and a 4-MOSFET amplifier circuit, both powered from a LiPo battery. The complete circuit is enclosed inside a CD case, and a simple flexible metal strip is used to make a contact sensor that will activate the player when the CD case is opened. The songs are saved on the SD card as WAV files with 32KHz sampling rate and 8-bit samples.
Musical holiday card
Here is a demo video of this: