#define out1 3
#define out2 11
#define out3 10

void setup() {
  pinMode(out1, OUTPUT);
  pinMode(out2, OUTPUT);
  pinMode(out3, OUTPUT);
}

void loop() {
  buzz(out1);
  buzz(out2);
  buzz(out3);
}

void buzz(int pin) {
  analogWrite(pin, 255);
  delay(10);
  digitalWrite(pin, LOW);
  delay(10);
}