To light up the hand using non-programmable LEDs like Adafruit Sequins, you will create a soft circuit. Conductive fabric tape works great on paper because it bends without breaking. If you are new to circuits, here are some important things to know before you get started:

  • A circuit is a path for electricity to travel along. The current will only flow when the circuit is closed, meaning it forms a loop.
  • For each finger, you will create two lines called traces. There is a positive trace that connects to one of the input/output pins on the CPX, and a negative trace that connects to one of the ground pins.
  • By running the positive and negative traces parallel to each other, you create a parallel circuit. In a parallel circuit, every LED is connected directly to the power source (in this case, the input/output pin). This allows you to connect four or five LEDs to each finger.
  • Like other kinds of components, LEDs have a positive and a negative side. In addition, LEDs have polarity, which means they only work when the positive side is connected to the positive side of the power source, and the negative side is connected to the negative side. Make sure you connect your LEDs in the right direction!
Don't let traces touch each other! This can cause a short circuit, an accidental connection between two parts of the circuit that can damage your components.

Working with LED Sequins

Adafruit LED Sequins come in packs of five, attached to a breakaway board. The pack recommended here has one of each color, but you can also buy a pack with five of one color.

They're nice because the positive (+) and negative (-) ends are clearly marked. Each LED also has an onboard resistor. That lets you use different color LEDs together without worrying about different voltage requirements.

The Sequins are not individually programmable, but you can turn them on or off or fade them in and out by varying the voltage coming through the pin on the CPX board. (See the MakeCode page to find out how to program them.)

If you connect multiple LEDs to one pin, they will all turn on, turn off, and fade at the same time.

Working with Conductive Fabric Tape

The peel-and-stick conductive fabric tape is easy to use. Just cut the length you need, peel a bit of the tape off one end, attach it to the cardstock, and then slowly press the tape down as you peel off the rest of the paper.

The glue on the back of the tape is also highly conductive! You can connect two pieces by laying one right over the other and firmly pressing them together.

To prevent a short circuit, make sure to keep each line of tape separate. If you need to, you can cut the tape to make it thinner.

If a cut edge frays, make sure no loose threads are touching other pieces of tape! Tuck in any loose threads and secure them with tape. Use clear tape if you have to cover one of the LEDs.

This guide was first published on Oct 28, 2019. It was last updated on Oct 28, 2019.

This page (Soft Circuit Basics) was last updated on Sep 30, 2020.