No-Sew Light-Up Wrist Cuff
Enhance your cosplay with soft circuits! In this simple project, you can make a simple felt cuff that lights up. We’ll also learn the science behind circuits and discover how to design your own.
You can get all the supplies for this project in the Make: Circuit Scout kit, Papercraft Circuits kit, or Origami Paper Circuits kit. Doing this project with students? Feel free to use my Google Slides presentation on the project or download the one-page printable project sheet. Want a quick set or slides of handouts on circuits? Check out lectrify’s lessons page.
A circuit is a loop made up of different components that allows electricity to flow. Circuits must have a power source, an output (load) like your LED, and a conductive material that allows the electrical energy to flow. The loop must be closed for a circuit to work. Your LED will light up when electricity flows from the battery through the light and back to the battery.
We use switches to open and close a circuit. In this project, we build our circuit into the cuff, so that when you put it on the circuit is completed. There are many different types of switches available for electronics and you may want to experiment with them to enhance your project.
The electricity in a circuit must flow in the right direction. Power flows from the negative (-) side of the battery (anode) to the positive (+) side of the battery (cathode). Some loads, like LEDs, must be connected in the right direction for them to work. When working on this project, be sure to note the * and – signs included in the diagrams.
- Battery – This is your power source. Use 3 volt coin batteries such as CR2025 or CR2032.
- LED – This is you output or load. These LEDs need 2-3 volts each. We often use 5 mm LED, but you can substitute jumbo 10 mm LEDs or mini 3mm LEDs as you prefer.
- Maker Tape – A conductive fabric material with an adhesive backing. You can also substitute copper tape (though it is more challenging in this project) or conductive thread, if you prefer to sew.
- Measure your wrist and add one inch. Cut a piece of felt to that length and at least 2 inches wide.
- On the right side, make two 1/2 inch vertical tabs roughly 1/2 inch from the end of the felt to create tabs.
- On the left side, cut two 1/2 horizontal slits roughly 1/2 inch from the edge. (Figure 1)
- Select an LED. The long lead is positive. The short lead is negative. Gently bend the leads out from the center. Place the LED in the center of the felt with the negative lead to the right and the positive lead to the left. (Figure 2)
- Starting on the right side, apply Maker Tape OVER the lead of the LED, run along the center of the felt, and wrap over and around the felt on the right side. (Figure 3) NOTE: It is best to measure and cut your tape before removing the white backing. If you take the backing off all at once that tape may stick to inself.
- Apply tape over OVER the positive lead of the LED and run along the center of the felt to approximately 1-1/2” from the end, as shown on the template below. Make a small loop of Maker Tape with the sticky side facing out. Use it to attach your battery, positive side DOWN. Apply a piece of Maker Tape from the top of the battery to the left side of the cuff. (Figure 4)
- Add extra tape on the left side between the horizontal slits and on the right side on the back of the tabs to ensure a good connection. These two spots form the switch. (Figures 3 and 4)
- Wrap the cuff around your wrist. Place the right side over the left and slide the tabs into the slits to complete the circuit and light it up. Decorate your cuff! (Figure 5)
In this project, we made a simple circuit with one LED, but you can add more lights using series or parallel circuits. In a series circuit, your power source must be the combined voltage of all your loads. In a parallel circuit, each component is wired back to the power source, so the voltage must only be as much as that of the highest load.
Try making your own parallel soft circuit with the diagram below! As a note, you’ll want to be sure to use LEDs that draw the same voltage, usually the same color or similar in color. If you pair a red LED that needs 2 volts with a blue LED that needs 3 volts, the electricity may flow into the red LED and skip the blue, because it will follow the path of least resistance. You can fix this by using resistors or simply pairing LEDs that have similar voltage needs. Check your LED documentation for information.
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