transmission+interference

transmission+interference -- circle draw

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Circle Draw is an instrument that plays with Persistence of Vision (P.O.V) to draw circles with a single laser diode. This creates a sharp drone sound where the pitch is controlled by the speed at which the circle is drawn - the speed of the motor.

A laser diode is lined up closely with a small rotating mirror that is at an angle to the laser. When the motor spins the mirror the laser dot is "drawn" faster than the eye can see the difference and we start to see a continuous red line and we can hear this by placing a solar cell in the path of the light. To get more intersting sounds it is good to blink the laser diode (either randomly or at a controlled rate) to break the constant drone. Added to this is the use of a servo to "twitch" the laser diode across the face of the mirror. Try changing the angle at which the light crosses the solar panel for subtle changes in sound.

How to build:
1. Glue small mirror at an angle on the end of the motor spindle
2. Glue motor and servo in place on wooden board
3. Glue laser diode to servo arm
4. Attach Arduino motor shield to Arduino
5. Wire up motors to Arduino
6. Wire up servos to Arduino
7. Wire up laser diodes to Arduino
8. Wire up potentiometers from breadboard to Arduino

Arduino Code:

/***********************************************

Arduino code for circle draw instrument

transmission+interference

***********************************************/

#include <Servo.h>

Servo myservo;
Servo myservo2;
int led = 4;
int led2 = 7;
long previousMillis = 0;
long previousMillis2 = 0;
long interval = 1000;
long randNumber;
long randNumber2;
long randNumber3;
long randNumber4;
int ledState = LOW;
int ledState2 = LOW;
int analogIn = A4;
int analogIn2 = A5;
int pot = 0;
int pot2 = 0;
int sensor = 0;
int sensor2 = 0;

void setup() {

  //Setup Channel A
  pinMode(12, OUTPUT); //Initiates Motor Channel A pin
  pinMode(9, OUTPUT); //Initiates Brake Channel A pin
 pinMode(13, OUTPUT);
 pinMode(8, OUTPUT);
 pinMode(4, OUTPUT);
 pinMode(7, OUTPUT);
 myservo.attach(10);
 myservo2.attach(5);
}

void loop(){
  sensor = analogRead(A4);
  sensor2 = analogRead(A5);
  pot = map(sensor, 0, 1023, 0, 255);
  pot2 = map(sensor2, 0, 1023, 0, 255);

  //forward @ full speed
  digitalWrite(12, HIGH); //Establishes forward direction of Channel A
  digitalWrite(9, LOW);   //Disengage the Brake for Channel A
  analogWrite(3, pot);   //Spins the motor on Channel A at full speed
  digitalWrite(13, HIGH); //Establishes forward direction of Channel A
  digitalWrite(8, LOW);   //Disengage the Brake for Channel A
  analogWrite(11, pot2);

  randNumber = random(500);

  unsigned long currentMillis = millis();

  if(currentMillis - previousMillis > randNumber) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;

    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW)
      ledState = HIGH;
    else
      ledState = LOW;

    // set the LED with the ledState of the variable:
    digitalWrite(led, ledState);
  }

   randNumber2 = random(500);


   if(currentMillis - previousMillis2 > randNumber2) {
    // save the last time you blinked the LED
    previousMillis2 = currentMillis;

    // if the LED is off turn it on and vice-versa:
    if (ledState2 == LOW)
      ledState2 = HIGH;
    else
      ledState2 = LOW;

    // set the LED with the ledState of the variable:
    digitalWrite(led2, ledState2);

  }

  randNumber3 = random(0, 10);
  myservo.write(randNumber3);
  randNumber4 = random(0, 5);
  myservo2.write(randNumber4);

  delay(10);

}

Links:
Vincent Van Uffelen
transmission+interference

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