Arduino code to follow X position water bath as linear resistor and output a tone.

waterBathPitchFollower.ino

void setup() {
  // initialize serial communications (for debugging only):
  Serial.begin(9600);
  pinMode(7, OUTPUT); //Left Plate
  pinMode(6, OUTPUT); //Right plate

}
int sens_flip = 0;
int av = 0;
void loop() {
  //Flips between plate to stop charge buildup on either side through ion migration
  if (sens_flip > 0) {
    digitalWrite(6, HIGH); //L PLate
    digitalWrite(7, LOW); //R Plate
    sens_flip--;
    delay(10);
  } else {
    sens_flip++;
    digitalWrite(7, HIGH);
    digitalWrite(6, LOW);
    delay(10);
    int sensorReading = analogRead(A0);
    av = sensorReading + 30*av; //Average the sensor reading
    av /= 31;
    Serial.println(sensorReading);
    int thisPitch = map(av, 0, 1024, 120, 1500);
    // play the pitch:
    tone(9, thisPitch);
  }
  delay(10);
}