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.
Step 1: build VCO using 7555 astable oscilator
Use wire diagram below to build the VCO on your breadboard. Though not pictured, please connect the 5v pin from the Arduino to the Vcc rails on your breadboard and ground on the Arduino to the ground rails on your breadboard.