A simple beat box using a relay for the beat and a servo for scratch sounds.
Turn the pot to control the speed (beats per minute). The beat is pre-programmed, but can be overwritten by holding the recording button and pressing the "beat in" button in the desired rhythm. The led provides guidance by flashing the bpm.
The light sensor controls the scratching servo. It's also timed to the bpm so it scratches in the right rhythm.
Made at the Fritzing Studio during TEI'10 at MIT Media Lab.