Cosplay Electronics 101: Simple Switched Circuits


Simple switched circuits are great for adding a few LEDs to your costumes. I use them for areas with fewer than 5 LEDs in a chain and who aren’t arduino controlled. Configurations like this work well for arms and legs, and places where you can’t run wires to a main harness.

Materials & Tools

  • A Soldering Iron & Solder
  • A pair of Wire Strippers and Scissors/Dykes
  • Your LEDs
  • 2-Pin JST wire (or you can use regular wire, but this is easier)
  • A Switched 2-Pin JST Breakout Board
  • A resistor of the correct size for your circuit & LED (I used 27 ±5% Ω)
  • (Optional) Heatshrink tubing & Electrical Tape
  • (Optional) Helping Hands

The Soldering Process

Split the JST wire and strip the ends.

Black wire indicates that it goes to ground, so insert it into one of the holes labeled GND for ground.

Twist the wire and bend it so that it stays in the hole. Make sure to have the insulation on the wire be as close to the breakout board as possible so there is a smaller possibility of shorts later.

Using your soldering iron, heat the metal pad (the hole you put wires into) and flow solder into the hole.

After soldering it should look like this, and the solder should be shiny.

Next, take your resistor, and bend one leg at a 90° angle. Insert this into the hole labeled SW (switch) — if you were to put it into the +/positive hole it would stay on constantly.

Here I’ve soldered the resistor in, and now we can cut off any bits that stick out from the board.

Slide your heat-shrink tubing over the the red wire (power), twist the wire around the other leg of the resistor, and liberally apply solder.

Carefully blast the heat-shrink with your heat gun, or lightly run the tip of your soldering iron against it.

Wrap electrical tape around the whole thing for further strain relief.

Mark the Anode (+) of your LED (the longer leg) and cut the legs so that they’re even (or do this after casting any gems).

Insert the LED into the end of your JST connector so that the Anode leg is in the + hole connected to the red wire of the JST connector, and the ground leg is in the black hole.

Check for shorts, and then you can plug in your battery (if you’re using the Adafruit switch I am, they need to have a JST connector attached, you can find some awesome options here!) and light your LED up! This method means that you can switch out your LED/gem if you want and reuse the switches for another costume or project.

This method also works with multiple LEDs, you just need to change the resistor size accordingly.