int potPin = A3; // Potentiometer output connected to analog pin 3
int potVal = 0; 


int redPin = 9;   // Red LED,   
int grnPin = 10;  // Green LED,
int bluPin = 11;  // Blue LED,  


int redVal = 0;   
int grnVal = 0;
int bluVal = 0;
const int sensorMin = 0;    
const int sensorMax = 600;  


void setup()
{
  pinMode(redPin, OUTPUT);  
  pinMode(grnPin, OUTPUT);   
  pinMode(bluPin, OUTPUT); 
}


void loop() {
  // read the sensor:
potVal = analogRead(potPin);   
  // map the sensor range to a range of four options:
  int range = map(potVal, sensorMin, sensorMax, 0, 3);

  // do something different depending on the range value:
  switch (range) {
    case 0:  // your hand is on the sensor
      digitalWrite(redPin, HIGH); 
      digitalWrite(grnPin, LOW); 
      digitalWrite(bluPin, LOW); 
      break;
    case 1:  // your hand is close to the sensor
      digitalWrite(redPin,LOW ); 
      digitalWrite(grnPin, HIGH); 
      digitalWrite(bluPin, LOW);  
      break;
    case 2:  // your hand is a few inches from the sensor
      digitalWrite(redPin,LOW ); 
      digitalWrite(grnPin,LOW ); 
      digitalWrite(bluPin, HIGH);
      break;
    case 3:  // your hand is nowhere near the sensor
      digitalWrite(redPin, HIGH); 
      digitalWrite(grnPin, HIGH); 
      digitalWrite(bluPin, HIGH);
      break;
  }
  delay(1);  // delay in between reads for stability
}