Arduino simple program for op-amp feedback.

opamp.ino

#define MIC A1
#define LED 3

void setup(){
  //for debug
  //Serial.begin(9600);
  pinMode(MIC, INPUT);
  pinMode(LED, OUTPUT);
}

void loop(){
  int sensor = analogRead(MIC);
  sensor = map(sensor, 0, 1023, 0, 255);
  analogWrite(LED, sensor);
  //for debug
  //Serial.println(sensor);
}