CustomKeys using an Arduino

CustomKeys is a customizable, Arduino-based, polyphonic synthesizer. The CustomKeys keyboard uses capacitive touch sensing – each key is made of a conductive material which, when touched, signals the synthesizer to emit a tone from the speaker. The CustomKeys library allows the user to choose an 8-note musical scale for the keys. Furthermore, users have a creative choice on the body design of their CustomKeys synth – users can use a provided laser cutter template or use any other material long as the basic requirements for the system to function are met.

Arduino CustomKeys

Special thanks to:
– Joe Marshall, whose code for the Arduino Octosynth ( is the basis of the CustomKeys library
– Instructables user blinkyblinky for documenting how to assemble the Arduino Octosynth


– Jumper cables (preferable to wires, but wires work just fine)You may find that the output sound is too quiet with the speaker alone.
In this case, you may want to build an amplifier circuit. Here are the parts you will need:
– An n-type MOSFET (I used an IRF9530)
– Two 100 Ohm resistors
– A 1.2K Ohm resistor
– A .47uF film capacitor
– A 220 uF electrolytic capacitor*Part of the box template was made with Rahul Bhargava’s BoxMaker

Step 2: Keyboard Assembly (Without Laser Cutter Template)

If you’re using the laser cutter template, please skip to step 4.

Arduino CustomKeys Circuit

Make a cool keyboard design using the colorful pieces of card stock. I like to fold my paper in half along the short edge, then along the long edge. Then, while it’s still folded, I cut my paper down the fold I made along the short edge (refer to the images for clarification). This yields two greeting card shaped pieces of paper. I only use one of them. Next, I take another color of cardstock, cut little rectangular shapes for the keys, and glue them onto one side of the card shaped paper (refer to the images).

Feel free to be creative with this part. Make a monster, a garden of flowers, or an original creation with card stock shapes. Try to make a design that will look nice with the conductive items that you will use for keys. **The folded part of the card shaped paper will be the top of the synth, so please plan your design accordingly. **

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You Will Need:
– The CustomKeys Arduino library – updated 05/15/13 (download below)
– 8 bits of conductive material for the keys (paperclips, brads, conductive tape, etc.)
– Colorful card stock paper (unless you’re going the laser cutter route)
– A soldering iron
– A boxcutter or x-acto knife
– Stick glue
– Wire clippers and strippers
– A set of 8 male header pins
– Electrical wire
– An Arduino ( I used the Uno)
– A USB for the Arduino
– A breadboard
– An 8 Ohm speaker

If you have access to a laser cutter:
– 16″ x 20″ birch board with 1/8″ thickness
– The box template (download below)*[/box]

For more detail: CustomKeys using an Arduino

About The Author

Ibrar Ayyub

I am an experienced technical writer with a Master's degree in computer science from BZU Multan University. I have written for various industries, mainly home automation, and engineering. I have a clear and simple writing style and am skilled in using infographics and diagrams. I am a great researcher and is able to present information in a well-organized and logical manner.

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