The circuit, sketches and process described here will allow you to produce melodies using an Arduino and a VCO. The sketches provided already have the melody for Mary Had a Little Lamb. You can easily change the melody in the code and potentially build upon this project to make polyphonic music with one Arduino and six VCOs.
• Arduino and USB cable
• 8Ω Speaker or connection to an audio amplifier
• VCO & Low pass circuits
1x 7555 Timer
2x 10kΩ Resister
1x 1µF capacitor
2x 100µF capacitor
• Guitar tuner, Musical Instrument or well trained musical ear.