 void loop() 
 {
   checkSerial();
-  
-  analogWrite(voltagePin, voltageTargetValue);
+
+  for(uint8_t i = 0; i < N; ++i)   
+    analogWrite(voltagePins[i], voltageTargetValue);
   
   delay(30);
 }


int voltagePin = 9;
int voltageValue = 0;
byte voltageTargetValue = 0;

#define MAX_VOLTAGE 50

void setup()
{
  pinMode(voltagePin, OUTPUT);
  Serial.begin(9600);
  Serial.println("Ready... enter: + -");
}

void checkSerial()

  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)
