 
-int voltagePin = 9;
-int voltageValue = 0;
+#define MAX_VOLTAGE 500
+#define N 3
+int voltagePins[N] = { 8, 9, 10 };
+int voltageValue = MAX_VOLTAGE;
 byte voltageTargetValue = 0;
-
-#define MAX_VOLTAGE 50
 
 void setup()
 {
-  pinMode(voltagePin, OUTPUT);
+  for(uint8_t i=0; i < N; ++i)
+    pinMode(voltagePins[i], OUTPUT);
   Serial.begin(9600);
   Serial.println("Ready... enter: + -");
+
+  voltageTargetValue = map(voltageValue, 0, MAX_VOLTAGE, 0, 255);
 }
 
 void checkSerial()

    Serial.print("New Voltage: ");
    Serial.print(voltageTargetValue);
    Serial.print("  ");
    Serial.print(voltageValue/10.f);
    Serial.println("V");
  }
}

  if(Serial.available())
  {
    byte character = (char)Serial.read();
    if(character == '\n')
      return;
    if(character == '\r')
      return;
      
    if(character == '-')
      voltageValue += 1;
    else if(character == '+')
      voltageValue -= 1;

    if(voltageValue < 0)
