This is really quick project that demonstrates the use of the Makey Makey's "Pro" functionality as a micro controller. In this project we use one of the 6 Analog input pins on the underside of the Makey Makey. This is a great project for people who are media artist types who want to begin using micro controllers to build physical interfaces for their projects.

The paper theremin uses a thick line of graphite to provide variable resistance to the micro controller, which allows continuous input from the Makey Makey, rather than discrete button presses.

For this project you will need:

1) A Makey Makey along with the alligator clips and any wires that come with it.

2) A computer with the Arduino IDE and Max MSP, or any program that creates sound and can read serial data. Instructions on how to install the drivers for the Makey Makey can be found here: Sparkfun.

3) Paper and pencil.

Optional:

4) A multi-meter to test the connection that you are getting in your circuit. Although it is not necessary, if you plan on doing DIY electronics a good multi-meter and the knowledge on how to use it will make troubleshooting your circuits and testing connections much easier.

Step 1: Draw a (Thick) Line

Step 1:

In order for the current to flow over the paper, we need to put down a thick layer of graphite- pencil lead- to act as a conductor. This is the most important step as a line that is too thin or not completely solid will break the circuit. When I did this, I used a thick carpenter's pencil and spent extra time making sure that there was enough graphite.

The length of the line determines the range of notes that you can get from the theremin. Try experimenting with different spirals, patterns and drawings to see how interacting with the different shapes changes the expression of the instrument.

Step 2: Connect the Circuit

Step 2:

Insert a small bit of wire into the A0 pin on the Makey Makey, and then attach the alligator clip to the exposed end. Then, connect the other side of that clip to the edge of the paper so that it completely overlaps the line that you drew.

Then, clip a different alligator clip to the portion of the Makey Makey marked "Earth" and to your body- either by holding on to the metal part of the clip, or by attaching it to some conductive jewelry. A ring works nicely for this, and if you have some extra solder laying around, then you can make one like mine!

Step 3: Programming the Makey Makey

Step 3:

Make sure that you have the Makey Makey / Arduino software installed, and then program it using the following code:

//Shamelessly stolen from example code
void setup() {
  Serial.begin(9600); // initialize serial communication at 9600 bits per second:
}

void loop() { // the loop routine runs over and over again forever:
  int sensorValue = analogRead(A0);// read the input on analog pin 0
  Serial.println(sensorValue);// print out the value you read:
  delay (100); //Necessary to communication to Max MSP
} //Simple

This code will allow the Makey Makey to send the data from the analog pin to the serial port so that other programs can access it. I use Max MSP because it has a built-in way of handling serial data and synthesizing music.

Step 4: (Optional) Testing the Connection

Step 4:

Using a multimeter will allow you to gain valuable insight about the way that electricity is flowing through your circuit, and it allows you to see how interacting with the graphite strip changes the voltages that are received by the Makey Makey.

Clip one probe of the multimeter to the "Earth" clip that you were holding on to from step 2, and hold the other probe in the hand you will use to play the theremin. Rub the probe along the strip, and you should see a change in voltage depending on how far it is from the clip on the paper.

Step 5: Play!

Check out the video! Yours can be different, but the rule about low notes being close to the clip and high notes being far away from the clip should still be true. If you are experiencing very choppy or meaningless data, you should check your connections, restart the Makey Makey by re-uploading the code, and try coloring in the line more.

Use can use this to:

Make music

Scrub through a video clip

Control a video game

... anything!