diff --git a/src/main/java/de/ph87/electro/circuit/Circuit.java b/src/main/java/de/ph87/electro/circuit/Circuit.java
index 096d20d..ed8956e 100644
--- a/src/main/java/de/ph87/electro/circuit/Circuit.java
+++ b/src/main/java/de/ph87/electro/circuit/Circuit.java
@@ -42,7 +42,7 @@ public class Circuit {
   public Circuit(final CircuitDto dto) {
     created = dto.getCreated();
     for (PartDto partDto : dto.getParts()) {
-      final Part part = Part.of(partDto);
+      final Part part = Part.of(this, partDto);
       verifyFree(part.getPosition());
       parts.add(part);
     }
@@ -56,7 +56,7 @@ public class Circuit {
 
   public void connect(final Junction a, final Junction b) {
     wires.add(new Wire(a, b));
-    setDirty();
+    evaluate();
   }
 
   public void disconnect(final Wire wire) {
@@ -66,7 +66,7 @@ public class Circuit {
     wires.remove(wire);
     wire.getA().getWires().remove(wire);
     wire.getB().getWires().remove(wire);
-    setDirty();
+    evaluate();
   }
 
   public <T extends Part> T addPart(final T part) {
@@ -76,7 +76,7 @@ public class Circuit {
     verifyFree(part.getPosition());
     parts.add(part);
     part.render();
-    setDirty();
+    evaluate();
     return part;
   }
 
@@ -86,15 +86,11 @@ public class Circuit {
     }
     verifyFree(position);
     part.setPosition(position);
-    setDirty();
-  }
-
-  private void setDirty() {
-    evaluate();
     dirty = true;
   }
 
   public void evaluate() {
+    dirty = true;
     Calculation.calculate(this);
     parts.forEach(Part::render);
   }
diff --git a/src/main/java/de/ph87/electro/circuit/CircuitIOService.java b/src/main/java/de/ph87/electro/circuit/CircuitIOService.java
index 27d0022..1460a42 100644
--- a/src/main/java/de/ph87/electro/circuit/CircuitIOService.java
+++ b/src/main/java/de/ph87/electro/circuit/CircuitIOService.java
@@ -8,7 +8,7 @@ import java.io.OutputStream;
 
 public class CircuitIOService {
 
-  private static final ObjectMapper objectMapper = new ObjectMapper();
+  private static final ObjectMapper objectMapper = new ObjectMapper().findAndRegisterModules();
 
   public static void write(final Circuit circuit, final OutputStream stream) throws IOException {
     objectMapper.writeValue(stream, new CircuitDto(circuit));
diff --git a/src/main/java/de/ph87/electro/circuit/CircuitPanel.java b/src/main/java/de/ph87/electro/circuit/CircuitPanel.java
index 3e6f83c..588d31b 100644
--- a/src/main/java/de/ph87/electro/circuit/CircuitPanel.java
+++ b/src/main/java/de/ph87/electro/circuit/CircuitPanel.java
@@ -20,9 +20,9 @@ public class CircuitPanel extends JPanel {
 
   public CircuitPanel() {
     new CircuitPanelDropTarget(this, circuit);
-    final Battery battery = circuit.addPart(new Battery(RST(2, 0)));
-    final Light light = circuit.addPart(new Light(RST(0, 2)));
-    final Poti poti = circuit.addPart(new Poti(RST(2, 2)));
+    final Battery battery = circuit.addPart(new Battery(circuit, RST(2, 0)));
+    final Light light = circuit.addPart(new Light(circuit, RST(0, 2)));
+    final Poti poti = circuit.addPart(new Poti(circuit, RST(2, 2)));
     poti.rotate();
     poti.rotate();
     light.rotate();
diff --git a/src/main/java/de/ph87/electro/circuit/CircuitPanelDropTarget.java b/src/main/java/de/ph87/electro/circuit/CircuitPanelDropTarget.java
index 21a705f..0182a54 100644
--- a/src/main/java/de/ph87/electro/circuit/CircuitPanelDropTarget.java
+++ b/src/main/java/de/ph87/electro/circuit/CircuitPanelDropTarget.java
@@ -23,23 +23,23 @@ public class CircuitPanelDropTarget extends AbstractDropTarget {
   protected boolean drop(final Point point, final String data) {
     final Position position = new Position(point);
     if (data.equals(Battery.class.getSimpleName())) {
-      circuit.addPart(new Battery(position));
+      circuit.addPart(new Battery(circuit, position));
     } else if (data.equals(ConnectorCorner.class.getSimpleName())) {
-      circuit.addPart(new ConnectorCorner(position));
+      circuit.addPart(new ConnectorCorner(circuit, position));
     } else if (data.equals(ConnectorEdge.class.getSimpleName())) {
-      circuit.addPart(new ConnectorEdge(position));
+      circuit.addPart(new ConnectorEdge(circuit, position));
     } else if (data.equals(ConnectorMiddle.class.getSimpleName())) {
-      circuit.addPart(new ConnectorMiddle(position));
+      circuit.addPart(new ConnectorMiddle(circuit, position));
     } else if (data.equals(Light.class.getSimpleName())) {
-      circuit.addPart(new Light(position));
+      circuit.addPart(new Light(circuit, position));
     } else if (data.equals(Switch1x1.class.getSimpleName())) {
-      circuit.addPart(new Switch1x1(position));
+      circuit.addPart(new Switch1x1(circuit, position));
     } else if (data.equals(Switch1x2.class.getSimpleName())) {
-      circuit.addPart(new Switch1x2(position));
+      circuit.addPart(new Switch1x2(circuit, position));
     } else if (data.equals(SwitchCross.class.getSimpleName())) {
-      circuit.addPart(new SwitchCross(position));
+      circuit.addPart(new SwitchCross(circuit, position));
     } else if (data.equals(Poti.class.getSimpleName())) {
-      circuit.addPart(new Poti(position));
+      circuit.addPart(new Poti(circuit, position));
     } else {
       throw new RuntimeException();
     }
diff --git a/src/main/java/de/ph87/electro/circuit/CircuitPanelMouseAdapter.java b/src/main/java/de/ph87/electro/circuit/CircuitPanelMouseAdapter.java
index efc67c8..d518384 100644
--- a/src/main/java/de/ph87/electro/circuit/CircuitPanelMouseAdapter.java
+++ b/src/main/java/de/ph87/electro/circuit/CircuitPanelMouseAdapter.java
@@ -56,7 +56,6 @@ class CircuitPanelMouseAdapter extends MouseAdapter {
       switch (event.getButton()) {
         case BUTTON1:
           part.action();
-          circuit.evaluate();
           circuitPanel.repaint();
           break;
         case BUTTON3:
diff --git a/src/main/java/de/ph87/electro/circuit/part/Part.java b/src/main/java/de/ph87/electro/circuit/part/Part.java
index 09931e6..845672b 100644
--- a/src/main/java/de/ph87/electro/circuit/part/Part.java
+++ b/src/main/java/de/ph87/electro/circuit/part/Part.java
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.junction.Junction;
 import de.ph87.electro.circuit.part.junction.JunctionDto;
 import de.ph87.electro.circuit.part.parts.*;
@@ -15,32 +16,40 @@ import static de.ph87.electro.CONFIG.PART_BACKGROUND;
 import static de.ph87.electro.CONFIG.RASTER;
 import static de.ph87.electro.circuit.part.Position.ZERO;
 
-@Getter
 @ToString(onlyExplicitlyIncluded = true)
 public abstract class Part {
 
+  private final Circuit circuit;
+
+  @Getter
   @ToString.Include
   private final String uuid;
 
+  @Getter
   @Setter
   @ToString.Include
   private String name;
 
+  @Getter
   private Position position;
 
+  @Getter
   private Orientation orientation = Orientation.R0;
 
+  @Getter
   private final List<Junction> junctions = new ArrayList<>();
 
   protected final Render render = new Render();
 
-  protected Part(final String name, final Position position) {
+  protected Part(final Circuit circuit, final String name, final Position position) {
+    this.circuit = circuit;
     this.uuid = UUID.randomUUID().toString();
     this.name = name;
     setPosition(position);
   }
 
-  protected Part(final PartDto dto) {
+  protected Part(final Circuit circuit, final PartDto dto) {
+    this.circuit = circuit;
     this.uuid = dto.getUuid();
     this.name = dto.getName();
     this.orientation = dto.getOrientation();
@@ -96,7 +105,12 @@ public abstract class Part {
     return junctions.stream().filter(junction -> junction.intersects(position)).findFirst();
   }
 
-  public void action() {
+  public final void action() {
+    _action();
+    evaluate();
+  }
+
+  public void _action() {
     // may be overwritten
   }
 
@@ -112,20 +126,26 @@ public abstract class Part {
     // may be overwritten
   }
 
+  protected void evaluate() {
+    if (circuit != null) {
+      circuit.evaluate();
+    }
+  }
+
   public List<InnerConnection> getInnerConnections() {
     return Collections.emptyList();
   }
 
-  public static Part of(final PartDto abstractDto) {
+  public static Part of(final Circuit circuit, final PartDto abstractDto) {
     return switch (abstractDto) {
-      case final BatteryDto dto -> new Battery(dto);
-      case final ConnectorCornerDto dto -> new ConnectorCorner(dto);
-      case final ConnectorEdgeDto dto -> new ConnectorEdge(dto);
-      case final ConnectorMiddleDto dto -> new ConnectorMiddle(dto);
-      case final LightDto dto -> new Light(dto);
-      case final Switch1x1Dto dto -> new Switch1x1(dto);
-      case final Switch1x2Dto dto -> new Switch1x2(dto);
-      case final SwitchCrossDto dto -> new SwitchCross(dto);
+      case final BatteryDto dto -> new Battery(circuit, dto);
+      case final ConnectorCornerDto dto -> new ConnectorCorner(circuit, dto);
+      case final ConnectorEdgeDto dto -> new ConnectorEdge(circuit, dto);
+      case final ConnectorMiddleDto dto -> new ConnectorMiddle(circuit, dto);
+      case final LightDto dto -> new Light(circuit, dto);
+      case final Switch1x1Dto dto -> new Switch1x1(circuit, dto);
+      case final Switch1x2Dto dto -> new Switch1x2(circuit, dto);
+      case final SwitchCrossDto dto -> new SwitchCross(circuit, dto);
       case null, default -> throw new RuntimeException();
     };
   }
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/Battery.java b/src/main/java/de/ph87/electro/circuit/part/parts/Battery.java
index a18fd1f..0705872 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/Battery.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/Battery.java
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.Orientation;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
@@ -40,14 +41,14 @@ public class Battery extends Part {
   @ToString.Include
   private double resistance = 0.05;
 
-  public Battery(final Position position) {
-    super("Batterie", position);
+  public Battery(final Circuit circuit, final Position position) {
+    super(circuit, "Batterie", position);
     minus = addJunction("MINUS", P10, P50);
     plus = addJunction("PLUS", P90, P50);
   }
 
-  public Battery(final BatteryDto dto) {
-    super(dto);
+  public Battery(final Circuit circuit, final BatteryDto dto) {
+    super(circuit, dto);
     minus = addJunction(dto.getMinus(), P10, P50);
     plus = addJunction(dto.getPlus(), P90, P50);
     voltage = dto.getVoltage();
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorCorner.java b/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorCorner.java
index 8388915..dc7821b 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorCorner.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorCorner.java
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
 import de.ph87.electro.circuit.part.junction.Junction;
@@ -17,14 +18,14 @@ public class ConnectorCorner extends Part {
 
   private final Junction j1;
 
-  public ConnectorCorner(final Position position) {
-    super("", position);
+  public ConnectorCorner(final Circuit circuit, final Position position) {
+    super(circuit, "", position);
     j0 = addJunction("J0", P10, P10);
     j1 = addJunction("J1", P90, P90);
   }
 
-  public ConnectorCorner(final ConnectorCornerDto dto) {
-    super(dto);
+  public ConnectorCorner(final Circuit circuit, final ConnectorCornerDto dto) {
+    super(circuit, dto);
     j0 = addJunction(dto.getJ0(), P10, P10);
     j1 = addJunction(dto.getJ1(), P90, P90);
   }
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorEdge.java b/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorEdge.java
index c4b7cb6..8dc7b4d 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorEdge.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorEdge.java
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
 import de.ph87.electro.circuit.part.junction.Junction;
@@ -17,14 +18,14 @@ public class ConnectorEdge extends Part {
 
   private final Junction j1;
 
-  public ConnectorEdge(final Position position) {
-    super("", position);
+  public ConnectorEdge(final Circuit circuit, final Position position) {
+    super(circuit, "", position);
     j0 = addJunction("J0", P10, P50);
     j1 = addJunction("J1", P50, P10);
   }
 
-  public ConnectorEdge(final ConnectorEdgeDto dto) {
-    super(dto);
+  public ConnectorEdge(final Circuit circuit, final ConnectorEdgeDto dto) {
+    super(circuit, dto);
     j0 = addJunction(dto.getJ0(), P10, P50);
     j1 = addJunction(dto.getJ1(), P50, P10);
   }
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorMiddle.java b/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorMiddle.java
index 31e9e8c..6c33d03 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorMiddle.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/ConnectorMiddle.java
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
 import de.ph87.electro.circuit.part.junction.Junction;
@@ -14,13 +15,13 @@ public class ConnectorMiddle extends Part {
 
   private final Junction junction;
 
-  public ConnectorMiddle(final Position position) {
-    super("", position);
+  public ConnectorMiddle(final Circuit circuit, final Position position) {
+    super(circuit, "", position);
     junction = addJunction("J", P50, P50);
   }
 
-  public ConnectorMiddle(final ConnectorMiddleDto dto) {
-    super(dto);
+  public ConnectorMiddle(final Circuit circuit, final ConnectorMiddleDto dto) {
+    super(circuit, dto);
     junction = addJunction(dto.getJunction(), P50, P50);
   }
 
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/Light.java b/src/main/java/de/ph87/electro/circuit/part/parts/Light.java
index f7a5e4c..37cc643 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/Light.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/Light.java
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.InnerConnection;
 import de.ph87.electro.circuit.part.Orientation;
 import de.ph87.electro.circuit.part.Part;
@@ -51,14 +52,14 @@ public class Light extends Part {
 
   private Color color = BULB_OFF_COLOR;
 
-  public Light(final Position position) {
-    super("Licht", position);
+  public Light(final Circuit circuit, final Position position) {
+    super(circuit, "Licht", position);
     a = addJunction("A", P10, P50);
     b = addJunction("B", P90, P50);
   }
 
-  public Light(final LightDto dto) {
-    super(dto);
+  public Light(final Circuit circuit, final LightDto dto) {
+    super(circuit, dto);
     a = addJunction(dto.getB(), P10, P50);
     b = addJunction(dto.getA(), P90, P50);
     resistance = dto.getResistance();
@@ -67,7 +68,7 @@ public class Light extends Part {
   }
 
   @Override
-  public void action() {
+  public void _action() {
     defect = false;
   }
 
diff --git a/src/main/java/de/ph87/electro/circuit/part/parts/Poti.java b/src/main/java/de/ph87/electro/circuit/part/parts/Poti.java
index e614067..3978355 100644
--- a/src/main/java/de/ph87/electro/circuit/part/parts/Poti.java
+++ b/src/main/java/de/ph87/electro/circuit/part/parts/Poti.java
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.InnerConnection;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
@@ -28,25 +29,29 @@ public class Poti extends Part {
   @Setter
   private double resistance = 10;
 
-  @Setter
   private double ratio = 0.0;
 
-  public Poti(final Position position) {
-    super("Poti", position);
+  public Poti(final Circuit circuit, final Position position) {
+    super(circuit, "Poti", position);
     common = addJunction("C", P10, P50);
     middle = addJunction("M", P50, P10);
     end = addJunction("E", P90, P50);
   }
 
-  protected Poti(final PotiDto dto) {
-    super(dto);
+  protected Poti(final Circuit circuit, final PotiDto dto) {
+    super(circuit, dto);
     common = addJunction(dto.getCommon().getName(), P10, P50);
     middle = addJunction(dto.getMiddle().getName(), P50, P10);
     end = addJunction(dto.getEnd().getName(), P90, P50);
   }
 
+  public void setRatio(final double ratio) {
+    this.ratio = ratio;
+    evaluate();
+  }
+
   @Override
-  public void action() {
+  public void _action() {
     if (ratio > 0.95) {
       ratio = 0;
     } else {
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 ab21eb3..6c3895d 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
@@ -1,11 +1,11 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.InnerConnection;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
 import de.ph87.electro.circuit.part.junction.Junction;
 import lombok.Getter;
-import lombok.Setter;
 import lombok.ToString;
 
 import java.awt.*;
@@ -22,24 +22,28 @@ public class Switch1x1 extends Part {
 
   private final Junction output;
 
-  @Setter
   private boolean state = false;
 
-  public Switch1x1(final Position position) {
-    super("Ausschalter", position);
+  public Switch1x1(final Circuit circuit, final Position position) {
+    super(circuit, "Ausschalter", position);
     common = addJunction("C", P10, P50);
     output = addJunction("O", P90, P50);
   }
 
-  public Switch1x1(final Switch1x1Dto dto) {
-    super(dto);
+  public Switch1x1(final Circuit circuit, final Switch1x1Dto dto) {
+    super(circuit, dto);
     common = addJunction(dto.getCommon(), P10, P50);
     output = addJunction(dto.getOutput(), P90, P50);
     state = dto.isState();
   }
 
+  public void setState(final boolean state) {
+    this.state = state;
+    evaluate();
+  }
+
   @Override
-  public void action() {
+  public void _action() {
     state = !state;
   }
 
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 1f8d9a2..d623cd7 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
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.InnerConnection;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
@@ -23,26 +24,30 @@ public class Switch1x2 extends Part {
 
   private final Junction output1;
 
-  @Setter
   private boolean state = false;
 
-  public Switch1x2(final Position position) {
-    super("Wechselschalter", position);
+  public Switch1x2(final Circuit circuit, final Position position) {
+    super(circuit, "Wechselschalter", position);
     common = addJunction("C", P10, P50);
     output0 = addJunction("O0", P90, P25);
     output1 = addJunction("O1", P90, P75);
   }
 
-  public Switch1x2(final Switch1x2Dto dto) {
-    super(dto);
+  public Switch1x2(final Circuit circuit, final Switch1x2Dto dto) {
+    super(circuit, dto);
     common = addJunction(dto.getCommon(), P10, P50);
     output0 = addJunction(dto.getOutput0(), P90, P25);
     output1 = addJunction(dto.getOutput1(), P90, P75);
     state = dto.isState();
   }
 
+  public void setState(final boolean state) {
+    this.state = state;
+    evaluate();
+  }
+
   @Override
-  public void action() {
+  public void _action() {
     state = !state;
   }
 
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 551396a..a6d5672 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
@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.part.parts;
 
+import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.InnerConnection;
 import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.Position;
@@ -25,19 +26,18 @@ public class SwitchCross extends Part {
 
   private final Junction output1;
 
-  @Setter
   private boolean state = false;
 
-  public SwitchCross(final Position position) {
-    super("Kreuzschalter", position);
+  public SwitchCross(final Circuit circuit, final Position position) {
+    super(circuit, "Kreuzschalter", position);
     common0 = addJunction("C0", P10, P25);
     common1 = addJunction("C1", P10, P75);
     output0 = addJunction("O0", P90, P25);
     output1 = addJunction("O1", P90, P75);
   }
 
-  public SwitchCross(final SwitchCrossDto dto) {
-    super(dto);
+  public SwitchCross(final Circuit circuit, final SwitchCrossDto dto) {
+    super(circuit, dto);
     common0 = addJunction(dto.getCommon0(), P10, P25);
     common1 = addJunction(dto.getCommon1(), P10, P75);
     output0 = addJunction(dto.getOutput0(), P90, P25);
@@ -45,8 +45,13 @@ public class SwitchCross extends Part {
     state = dto.isState();
   }
 
+  public void setState(final boolean state) {
+    this.state = state;
+    evaluate();
+  }
+
   @Override
-  public void action() {
+  public void _action() {
     state = !state;
   }
 
diff --git a/src/main/java/de/ph87/electro/sidebar/Sidebar.java b/src/main/java/de/ph87/electro/sidebar/Sidebar.java
index c7a7710..1c6bcb1 100644
--- a/src/main/java/de/ph87/electro/sidebar/Sidebar.java
+++ b/src/main/java/de/ph87/electro/sidebar/Sidebar.java
@@ -28,15 +28,15 @@ public class Sidebar extends JPanel {
     });
     add(toggleDetails);
 
-    add(new Battery(Position.ZERO));
-    add(new ConnectorCorner(Position.ZERO));
-    add(new ConnectorEdge(Position.ZERO));
-    add(new ConnectorMiddle(Position.ZERO));
-    add(new Light(Position.ZERO));
-    add(new Switch1x1(Position.ZERO));
-    add(new Switch1x2(Position.ZERO));
-    add(new SwitchCross(Position.ZERO));
-    add(new Poti(Position.ZERO));
+    add(new Battery(null, Position.ZERO));
+    add(new ConnectorCorner(null, Position.ZERO));
+    add(new ConnectorEdge(null, Position.ZERO));
+    add(new ConnectorMiddle(null, Position.ZERO));
+    add(new Light(null, Position.ZERO));
+    add(new Switch1x1(null, Position.ZERO));
+    add(new Switch1x2(null, Position.ZERO));
+    add(new SwitchCross(null, Position.ZERO));
+    add(new Poti(null, Position.ZERO));
     setPreferredSize(new Dimension(0, 200));
   }
 
diff --git a/src/test/java/de/ph87/electro/circuit/CalculationServiceTest.java b/src/test/java/de/ph87/electro/circuit/CalculationServiceTest.java
index 05fdbcd..1302ac8 100644
--- a/src/test/java/de/ph87/electro/circuit/CalculationServiceTest.java
+++ b/src/test/java/de/ph87/electro/circuit/CalculationServiceTest.java
@@ -16,8 +16,8 @@ class CalculationServiceTest {
   @Test
   void test() {
     final Circuit circuit = new Circuit();
-    final Battery battery = circuit.addPart(new Battery(RST(0, 0)));
-    final Light light = circuit.addPart(new Light(RST(0, 1)));
+    final Battery battery = circuit.addPart(new Battery(circuit, RST(0, 0)));
+    final Light light = circuit.addPart(new Light(circuit, RST(0, 1)));
     circuit.connect(battery.getMinus(), light.getA());
     circuit.connect(battery.getPlus(), light.getB());
 
diff --git a/src/test/java/de/ph87/electro/circuit/io/CircuitIOServiceTest.java b/src/test/java/de/ph87/electro/circuit/io/CircuitIOServiceTest.java
index 6188632..ce310a1 100644
--- a/src/test/java/de/ph87/electro/circuit/io/CircuitIOServiceTest.java
+++ b/src/test/java/de/ph87/electro/circuit/io/CircuitIOServiceTest.java
@@ -22,8 +22,8 @@ class CircuitIOServiceTest {
   @Test
   void serialization() throws IOException {
     final Circuit circuit = new Circuit();
-    final Battery battery = circuit.addPart(new Battery(RST(0, 0)));
-    final Light light = circuit.addPart(new Light(RST(0, 1)));
+    final Battery battery = circuit.addPart(new Battery(circuit, RST(0, 0)));
+    final Light light = circuit.addPart(new Light(circuit, RST(0, 1)));
     circuit.connect(battery.getPlus(), light.getB());
     circuit.connect(light.getA(), battery.getMinus());
     check(circuit);
diff --git a/src/test/java/de/ph87/electro/circuit/part/parts/BatteryLightTest.java b/src/test/java/de/ph87/electro/circuit/part/parts/BatteryLightTest.java
index 8ddcaa2..af13e95 100644
--- a/src/test/java/de/ph87/electro/circuit/part/parts/BatteryLightTest.java
+++ b/src/test/java/de/ph87/electro/circuit/part/parts/BatteryLightTest.java
@@ -14,9 +14,9 @@ public class BatteryLightTest {
 
   private static final Circuit CIRCUIT = new Circuit();
 
-  private static final Battery battery = CIRCUIT.addPart(new Battery(RST(0, 0)));
+  private static final Battery battery = CIRCUIT.addPart(new Battery(CIRCUIT, RST(0, 0)));
 
-  private static final Light light = CIRCUIT.addPart(new Light(RST(0, 1)));
+  private static final Light light = CIRCUIT.addPart(new Light(CIRCUIT, RST(0, 1)));
 
   @BeforeAll
   public static void setUp() {
diff --git a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x1Test.java b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x1Test.java
index 05059e7..3d71d20 100644
--- a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x1Test.java
+++ b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x1Test.java
@@ -15,11 +15,11 @@ public class BatterySwitcher1x1Test {
 
   private static final Circuit CIRCUIT = new Circuit();
 
-  private static final Battery battery = CIRCUIT.addPart(new Battery(RST(0, 0)));
+  private static final Battery battery = CIRCUIT.addPart(new Battery(CIRCUIT, RST(0, 0)));
 
-  private static final Switch1x1 switcher = CIRCUIT.addPart(new Switch1x1(RST(0, 1)));
+  private static final Switch1x1 switcher = CIRCUIT.addPart(new Switch1x1(CIRCUIT, RST(0, 1)));
 
-  private static final Light light = CIRCUIT.addPart(new Light(RST(1, 0)));
+  private static final Light light = CIRCUIT.addPart(new Light(CIRCUIT, RST(1, 0)));
 
   @BeforeAll
   public static void setUp() {
diff --git a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x2Test.java b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x2Test.java
index 163406e..921bd41 100644
--- a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x2Test.java
+++ b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher1x2Test.java
@@ -15,13 +15,13 @@ public class BatterySwitcher1x2Test {
 
   private static final Circuit CIRCUIT = new Circuit();
 
-  private static final Battery battery = CIRCUIT.addPart(new Battery(RST(0, 0)));
+  private static final Battery battery = CIRCUIT.addPart(new Battery(CIRCUIT, RST(0, 0)));
 
-  private static final Switch1x2 switcher = CIRCUIT.addPart(new Switch1x2(RST(0, 2)));
+  private static final Switch1x2 switcher = CIRCUIT.addPart(new Switch1x2(CIRCUIT, RST(0, 2)));
 
-  private static final Light light0 = CIRCUIT.addPart(new Light(RST(1, 1)));
+  private static final Light light0 = CIRCUIT.addPart(new Light(CIRCUIT, RST(1, 1)));
 
-  private static final Light light1 = CIRCUIT.addPart(new Light(RST(1, 3)));
+  private static final Light light1 = CIRCUIT.addPart(new Light(CIRCUIT, RST(1, 3)));
 
   @BeforeAll
   public static void setUp() {
diff --git a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher2x2Test.java b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher2x2Test.java
index fedf1b7..03b7a75 100644
--- a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher2x2Test.java
+++ b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcher2x2Test.java
@@ -15,13 +15,13 @@ public class BatterySwitcher2x2Test {
 
   private static final Circuit CIRCUIT = new Circuit();
 
-  private static final Battery battery = CIRCUIT.addPart(new Battery(RST(0, 0)));
+  private static final Battery battery = CIRCUIT.addPart(new Battery(CIRCUIT, RST(0, 0)));
 
-  private static final Switch1x2 switcher0 = CIRCUIT.addPart(new Switch1x2(RST(0, 1)));
+  private static final Switch1x2 switcher0 = CIRCUIT.addPart(new Switch1x2(CIRCUIT, RST(0, 1)));
 
-  private static final Switch1x2 switcher1 = CIRCUIT.addPart(new Switch1x2(RST(1, 1)));
+  private static final Switch1x2 switcher1 = CIRCUIT.addPart(new Switch1x2(CIRCUIT, RST(1, 1)));
 
-  private static final Light light = CIRCUIT.addPart(new Light(RST(1, 0)));
+  private static final Light light = CIRCUIT.addPart(new Light(CIRCUIT, RST(1, 0)));
 
   @BeforeAll
   public static void setUp() {
diff --git a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcherCrossTest.java b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcherCrossTest.java
index 8b6dd24..2e814f0 100644
--- a/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcherCrossTest.java
+++ b/src/test/java/de/ph87/electro/circuit/part/parts/BatterySwitcherCrossTest.java
@@ -15,15 +15,15 @@ public class BatterySwitcherCrossTest {
 
   private static final Circuit CIRCUIT = new Circuit();
 
-  private static final Battery battery = CIRCUIT.addPart(new Battery(RST(0, 0)));
+  private static final Battery battery = CIRCUIT.addPart(new Battery(CIRCUIT, RST(0, 0)));
 
-  private static final Switch1x2 switcher0 = CIRCUIT.addPart(new Switch1x2(RST(0, 1)));
+  private static final Switch1x2 switcher0 = CIRCUIT.addPart(new Switch1x2(CIRCUIT, RST(0, 1)));
 
-  private static final SwitchCross switcherX = CIRCUIT.addPart(new SwitchCross(RST(1, 1)));
+  private static final SwitchCross switcherX = CIRCUIT.addPart(new SwitchCross(CIRCUIT, RST(1, 1)));
 
-  private static final Switch1x2 switcher1 = CIRCUIT.addPart(new Switch1x2(RST(2, 1)));
+  private static final Switch1x2 switcher1 = CIRCUIT.addPart(new Switch1x2(CIRCUIT, RST(2, 1)));
 
-  private static final Light light = CIRCUIT.addPart(new Light(RST(2, 0)));
+  private static final Light light = CIRCUIT.addPart(new Light(CIRCUIT, RST(2, 0)));
 
   @BeforeAll
   public static void setUp() {