vplt level fix

hobu_doorbell/app.js

@@ -37,7 +37,7 @@ ai.on(Tinkerforge.BrickletAnalogInV2.CALLBACK_VOLTAGE,
     var v = voltage/1000.0;
     console.log('Voltage: ' + v + ' V');
 
-    if(v > 1) {
+    if(v > 3) {
       if(readyForNextNotification) {
         radicalChange = true;
         readyForNextNotification = false;