Inspiration

I really enjoy going to the gym to release my emotions, especially if I’m angry. I think it’s funny that on the outside I look like a person just working out, but on the inside I imagine myself making angry facial expressions. The physical act of working out feels like I get to channel my anger and that was the idea behind this project. I chose a punching bag made out of conductive fabric for my switch. When you punch it, you’re transferring your anger onto the bag which then swings and makes contact with your inner angry self which I have represented by the circuit with two red LEDs acting as the angry eyes of the painted emoji.

Materials

Electronics

• Perfboard (a.k.a. protoboard)
• 2× red LEDs
• 2× 220 Ω resistors (one per LED branch)
• Battery holder for 3× AAA batteries
• A little extra solid-core wire (for jumpers and the “contact wires”)
  Solder + soldering iron
• Wires

Structure & Art Materials

• Base board (wood) big enough to hold both the LED “table” and the punching-bag stand
• Craft wood circle (for the emoji face)
• Small wooden cubes (for table legs)
• 2 wide wooden boards (side supports for the punching-bag stand)
• 1 top board (crossbar)
• Small wooden stick/dowel (core of the punching bag)
• Cotton (stuffing)
• Conductive fabric (outer “bag” layer)
• String
• Hot glue + glue sticks
• Wood glue

Tools

• Wire cutters/strippers
• Drill + drill bits (small bit for the bag string hole; larger bits for LED “eye” holes)
• Paint + brush (yellow for emoji face, black for stand)
• Pencil/marker for layout

Step-By-Step Guide

1. Lay out the parts on the perfboard. Put two red LEDs where you want the “eyes” to be, and place a 220 Ω resistor in series with each LED (one resistor per LED).
   
2. Solder the parallel circuit. Make two separate branches:
   
   • Branch 1: resistor → LED
     
   • Branch 2: resistor → LED
     
     Join both branch starts together (positive node) and both branch ends together (ground node).
     
3. Solder the battery holder leads. Solder the battery holder – lead to the ground node. Solder the battery holder + lead to the positive side but leave an intentional gap before the branches so the circuit is open.
   
4. Create the “contact wires” for the switch. On each side of that gap, solder a stiff bare wire sticking out. Position them close together but not touching.
   
5. Make the emoji face. Cut a wood circle, drill two holes where the LEDs will pass through, and paint it like an angry emoji.
   
6. Mount the emoji face over the LEDs. Place the painted circle over the perfboard so the LEDs poke through the holes like eyes.
   
7. Build the circuit “table.” Glue wooden cubes into four stacks (3 cubes per stack). Glue the four stacks under the circuit so it stands like a table with 4 legs.
   
8. Make the punching bag. Wrap cotton around a small stick. Hot glue conductive fabric around it to form a mini bag. Drill a small hole at the top of the stick and tie a string through it.
   
9. Add the target. Paint a small circle like a target and hot glue it to the front of the punching bag.
   
10. Build the punching bag stand. Glue two wide wooden boards upright on the base board. Drill a hole in the center of a top board, tie the bag string through the hole so it hangs, then glue the top board onto the side boards.
    
11. Paint the stand. Paint the punching bag stand black (and touch up anything else).
    
12. Position for the punch-switch effect. Place the punching bag stand close enough to the circuit so the bag doesn’t touch the two contact wires at rest, but does hit them when punched.
    
13. Test and tune. Insert 3 AAA batteries. If it lights without punching, bend the contact wires farther apart. If it doesn’t light when punched, bring them closer or move the stand slightly nearer until punching reliably turns the LEDs on.