diff --git a/src/main/java/de/ph87/electro/circuit/Circuit.java b/src/main/java/de/ph87/electro/circuit/Circuit.java
index d003f4e..3fd49c1 100644
--- a/src/main/java/de/ph87/electro/circuit/Circuit.java
+++ b/src/main/java/de/ph87/electro/circuit/Circuit.java
@@ -5,9 +5,6 @@ import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.PartDto;
 import de.ph87.electro.circuit.part.Position;
 import de.ph87.electro.circuit.part.junction.Junction;
-import de.ph87.electro.circuit.part.parts.Battery;
-import de.ph87.electro.circuit.part.parts.Poti;
-import de.ph87.electro.circuit.part.parts.Voltmeter;
 import de.ph87.electro.circuit.wire.Wire;
 import de.ph87.electro.circuit.wire.WireDto;
 import lombok.Getter;
@@ -22,8 +19,6 @@ import java.util.List;
 import java.util.Optional;
 import java.util.stream.Stream;
 
-import static de.ph87.electro.circuit.part.Position.RST;
-
 public class Circuit {
 
   @Getter
@@ -42,6 +37,7 @@ public class Circuit {
     this.created = ZonedDateTime.now().format(DateTimeFormatter.ISO_OFFSET_DATE_TIME);
   }
 
+  @SuppressWarnings("unused")
   public Circuit(final File file, final CircuitDto dto) {
     created = dto.getCreated();
     for (PartDto partDto : dto.getParts()) {
diff --git a/src/main/java/de/ph87/electro/circuit/demo/Demos.java b/src/main/java/de/ph87/electro/circuit/demo/Demos.java
index f94b536..aa82a77 100644
--- a/src/main/java/de/ph87/electro/circuit/demo/Demos.java
+++ b/src/main/java/de/ph87/electro/circuit/demo/Demos.java
@@ -7,6 +7,7 @@ import de.ph87.electro.circuit.part.parts.Voltmeter;
 
 import static de.ph87.electro.circuit.part.Position.RST;
 
+@SuppressWarnings("unused")
 public class Demos {
 
   public static Circuit potiAndVoltmeter() {
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x1.java b/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x1.java
index 3c81d5f..5fa510d 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x1.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x1.java
@@ -12,7 +12,6 @@ import java.awt.*;
 import java.util.List;
 
 import static de.ph87.electro.CONFIG.*;
-import static de.ph87.electro.CONFIG.NO_RESISTANCE;
 
 @Getter
 @ToString(callSuper = true)
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x2.java b/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x2.java
index 6524b30..0229791 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x2.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/Switch1x2.java
@@ -11,7 +11,6 @@ import lombok.ToString;
 import java.util.List;
 
 import static de.ph87.electro.CONFIG.*;
-import static de.ph87.electro.CONFIG.NO_RESISTANCE;
 
 @Getter
 @ToString(callSuper = true)
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/SwitchCross.java b/src/main/java/de/ph87/electro/circuit/part/parts/SwitchCross.java
index f5e59a0..c660a78 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/SwitchCross.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/SwitchCross.java
@@ -11,7 +11,6 @@ import lombok.ToString;
 import java.util.List;
 
 import static de.ph87.electro.CONFIG.*;
-import static de.ph87.electro.CONFIG.NO_RESISTANCE;
 
 @Getter
 @ToString(callSuper = true)
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/Voltmeter.java b/src/main/java/de/ph87/electro/circuit/part/parts/Voltmeter.java
index a9ff6c6..e87764c 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/Voltmeter.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/Voltmeter.java
@@ -36,7 +36,7 @@ public class Voltmeter extends Part {
 
   private double min = -3;
 
-  private double max = +3;
+  private double max = 3;
 
   private double voltage;