Making a keyboard sound like a (strummed) guitar by using:

  1. A MIDI keyboard to determine the chord
  2. An Arduino to determine which string is being played
  3. A piece of software to remap the keyboard chord to a guitar chord, and play only the notes that the Arduino says to
Simple, really!

In principle, the circuit is very simple - the Arduino contains six switches made from copper wire. Each digital input is a pull-down resister giving a 0 input on D3-D8. When the plectrum/pick makes contact with the string/wire, this completes a circuit to pull the input to 1.

The Arduino needs only the standard Firmata code to be loaded into it.

The Processing code needs the dependancies:

  • The Minibus
  • Arduino (Firmata)


The wires are wound tight around the LEGO, but inevitably become slack. Maybe solid core, or strips of metal would be better?

The tape on the coin is in the centre so it can make an electrical connection when strummed in either direction

Use a smooth sided coin, to stop the sound triggering repeated if/when the string hits the serrated edge. Brian May always used a sixpence as his pick, so I'm in good company ;) It's just a shame I don't have a sixpence!

Tape the unit to the desk.. it _will_ move.



Download the The Strummer source code