Introduction: Arduino String Instrument

 
Sure you can use LDR's, potentiometers and buttons to generate sounds, but what about strings?

When I began thinking about an Arduino string instrument, I realized what I wanted to create was a soft potentiometer.  I found my inspiration from Hannah Perner-Wilson's Fabric Potentiometer http://www.kobakant.at/DIY/?p=543.




Step 1: Parts

  •      Arduino Microcontroller
  •     3.3Ω resistor (1 per string)
  •     Conductive thread Lame Lifesaver Lamé Lifesaver
  •     Nickel/Copper/Cobalt Fabric Tape http://www.lessemf.com/fabric.html
  •     8Ω speaker (1 per string)
  •     Solderless breadboard
  •     22-AWG hookup wire
  •     30-AWG wire (optional)
  •     Wooden Dowel
  •     Metal nails or small screw eyes
  •     Drill
  •     Saw
  •     Needle
  •     Scissors
  •     Wire Stripper
  •     Pencil or marker
  •     Box

Step 2: How It Works

Each string is basically a potentiometer that controls the sound of a speaker.

Step 3: Building the Instrument

1. Cut two pieces of a wooden dowel. Your length is determined by how long you want your bridge to be. The dowels purpose here is to keep the strings away from your GND.

2.Mark where you want to drill holes on your dowels. Remember, you want to keep the strings off your GND. You should drill holes so that when you string the instrument the strings are parallel to each other.

3.Using a glue gun, fix your dowel onto your box.

4. Either drill holes for nails or screws on the outer side of your dowels or  solder 30 AWG wire to eye screws and thread them through the dowels. If you are doing the the eye screws, one side goes to the analog pins, the other goes to power through a 3.3Ω resistor. I used red wires on one side to go to power and yellow wires to go to the analog pins. For the demo version the alligator clips attach to one nail connecting together an analog input and power through a resistor.


Step 4: Making Connections

1. You'll have to figure out a way to connect the tape to GND on the Arduino. One option is to use alligator clips. Another is to use brads and solder them together on the inside.

2. Using the conductive thread on a needle, attach the conductive thread to the screws or nails. Tightly string the threads across. Weave the thread across at least twice. Use one string to attach all the nails or screws. 

3. Connect one nail or screw to power through the 3.3Ω resistor .

4. Connect one nail or screw to an analog pin.

4. Attach at least one 8Ω speaker through a 100Ω resistor to a digital pin.

5. Create a pick or bow. It can be anything as long as it is conductive.

Step 5: The Tone Library

The Tone Library can be used to produce square-waves of the specified frequency on any Arduino pin. You can set the duration of the sound or use the method stop() to stop the sound.

To play a tone, connect a pin to a piezo buzzer or a speaker.

For this demo, I used a 8Ω speaker connected to pin 7 through a 100Ω resistor.


To use the library, you need to instantiate an instance of Tone:

	#include <Tone.h>

Tone notePlayer;

void setup(void){
     //the number reflects the speaker pin
     notePlayer.begin(7);
}
void loop(){
     //To play a note:
     notePlayer.play(NOTE_B3);
}

These are the methods that you can use with this Library:

 begin() - prepares a pin for playing a tone.
 isPlaying() - returns true if tone is playing, false if not.
play() - play a tone.
stop() - stop playing a tone.

 

This is a list of constant values of frequencies for notes:
Constant NameFrequency (Hz)
NOTE_B2 123
NOTE_C3 131
NOTE_CS3 139
NOTE_D3 147
NOTE_DS3 156
NOTE_E3 165
NOTE_F3 175
NOTE_FS3 185
NOTE_G3 196
NOTE_GS3 208
NOTE_A3 220
NOTE_AS3 233
NOTE_B3 247
NOTE_C4 262
NOTE_CS4 277
NOTE_D4 294
NOTE_DS4 311
NOTE_E4 330
NOTE_F4 349
NOTE_FS4 370
NOTE_G4 392
NOTE_GS4 415
NOTE_A4 440
NOTE_AS4 466
NOTE_B4 494
NOTE_C5 523
NOTE_CS5 554
NOTE_D5 587
NOTE_DS5 622
NOTE_E5 659
NOTE_F5 698
NOTE_FS5 740
NOTE_G5 784
NOTE_GS5 831
NOTE_A5 880
NOTE_AS5 932
NOTE_B5 988
NOTE_C6 1047
NOTE_CS6 1109
NOTE_D6 1175
NOTE_DS6 1245
NOTE_E6 1319
NOTE_F6 1397
NOTE_FS6 1480
NOTE_G6 1568
NOTE_GS6 1661
NOTE_A6 1760
NOTE_AS6 1865
NOTE_B6 1976
NOTE_C7 2093
NOTE_CS7 2217
NOTE_D7 2349
NOTE_DS7 2489
NOTE_E7 2637
NOTE_F7 2794
NOTE_FS7 2960
NOTE_G7 3136
NOTE_GS7 3322
NOTE_A7 3520
NOTE_AS7 3729
NOTE_B7 3951
NOTE_C8 4186
NOTE_CS8 4435
NOTE_D8 4699
NOTE_DS8 4978


More information can be found here:ToneLibraryDocumentation

Step 6: Putting It Altogether

Here is code for a two speaker instrument:
	#include <Tone.h>


int potValue;
int potValue2;

Tone speaker[2];
int notes[] = { 
  NOTE_A3,
  NOTE_B3,
  NOTE_C4,
  NOTE_D4,
  NOTE_E4,
  NOTE_F4,
  NOTE_G4,
  NOTE_A4,
  NOTE_B4,
  NOTE_C5,
  NOTE_D5,
  NOTE_E5,
  NOTE_F5,
  NOTE_G5,
  NOTE_A5,
  NOTE_B5,
  NOTE_C6};
void setup() {
  // initialize serial communications at 9600 bps:
  Serial.begin(9600); 
  speaker[0].begin(7);
  speaker[1].begin(8);
}
void loop() {

  potValue = analogRead(A0);   // read the pot value
 
 Serial.println(potValue);
 if (potValue<100){
    speaker[0].play(notes[0]);
     speaker[1].play(notes[12]);
  } 
  else if (potValue<200){
    speaker[0].play(notes[1]);
    speaker[1].play(notes[11]);
  }
  else if (potValue<250){
    speaker[0].play(notes[2]);
    speaker[1].play(notes[10]);
  }
  else if (potValue<320){
    speaker[0].play(notes[3]);
    speaker[1].play(notes[9]);
  }
  else if (potValue<400){
    speaker[0].play(notes[4]);
    speaker[1].play(notes[8]);
  }
  else if (potValue<450){
    speaker[0].play(notes[5]);
    speaker[1].play(notes[7]);
  }
  else if (potValue<500){
    speaker[0].play(notes[6]);
    speaker[1].play(notes[4]);
  }
  else if (potValue<550){
    speaker[0].play(notes[7]);
    speaker[1].play(notes[3]);
  }
  else if (potValue<700){
    speaker[0].play(notes[8]);
    speaker[1].play(notes[2]);
  }
  else if (potValue<900){
    speaker[0].play(notes[9]);
    speaker[1].play(notes[1]);
  }
  else{
    speaker[0].stop();
    speaker[1].stop();
  }

Comments

author
rsanly made it!(author)2014-08-29

it's cool man

author
Kiteman made it!(author)2011-02-09

Any chance of a recording?

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