Time to add lights! First, you'll make a soft circuit using conductive fabric tape. Next, you'll connect the Circuit Playground Express and attach the LEDs. After you're done, you'll be ready to plug in your CPX, program it in MakeCode, and make your lights flash!

Make the Base for the Circuit

Take a piece of cardstock and trace around the hand used to make the taped model. Spread the fingers so they match the taped hand.

Cut around the inside of the outline you drew, so that the tracing is skinnier than the taped hand. That way you'll be able to fit it inside the hand.

Square off the tops of the fingers and the spaces between the fingers.

The front of the cardboard base is the side that matches the front of the taped hand.

Make the Negative Traces on the Back of the Hand

One the back of the cardstock hand, attach a piece of conductive fabric tape long enough to reach from about the middle of the hand to the bottom, bending it around the bottom and over to the front.

Then attach the negative trace for the first finger. Connect it to the main piece by overlapping it, then run it up along one edge of the finger, up over the top, and down along the front.

Since you need room for two traces on the front side of the finger, you may want to cut the tape at the point where it bends over to the front so the front portion is thinner.

Repeat with the remaining fingers.

When you are done, the back of the hand should look like a tree with five branches.

The front of each finger should have a negative trace running along one side. The "trunk" of the tree should bend up around the bottom of the hand.

Add the Positive Traces to the Front of the Hand

Each positive trace will connect to an input/output (I/O) pin on the CPX board. The main negative trace will connect to a ground (GND) pad.

On the front of the hand, place the CPX in the middle and trace around it. If you are going to power the CPX board with the battery holder, the JST battery connector should be pointing down, towards the wrist. If you're going to use the USB cable to power it, rotate the board so the USB jack is facing down.

Next, mark the I/O pins you plan to use for each finger, from A1 to A7. Be sure to write the name of each pin next to it so you can match them up with the board later! In this example, the pins used are:

  • A6 - thumb
  • A5 - pointer finger
  • A4 - middle finger
  • A3 - ring finger, and
  • A2 - pinky.

Also mark the GND pad you want to use.

Now, attach the first positive trace tape to the first finger. It should go from near the top of the finger to the pin you marked for it on the board. Make sure the positive and negative traces aren't touching!

Do the same with the remaining fingers. Add a piece of tape to the main negative trace on the bottom so it reaches the GND pin.

Attach the CPX Board to the Circuit

Attach an adhesive dot to the back of the CPX board.

Attach the board to the marking on the cardstock, making sure that each pin lines up with the correct piece of conductive tape.

Use short pieces of conductive tape on top of the CPX board to secure each pin to the proper spot. Make sure the tape only touches the correct pin!

Attach the LED Sequins

Lay the LEDs on the traces on each finger. Make sure the positive and negative sides are on the correct trace!

When you are happy with the placement secure them with short pieces of conductive tape over the ends. Press the tape firmly to make a good connection.

For added security, you can attach a piece of Z-Axis Conductive Tape to the back of each LED. This is basically a sheet of conductive glue that will hold the LED in place. It won't cause a short circuit because it is only conductive to the material directly below it.

Optional: Touch Control

The CPX gives you several ways to trigger your program. If you want to add touch control, cut a strip of cardstock and attach it to the bottom of the hand with clear or masking tape so it can bend up like a hinge.

Then run a piece of conductive tape from an unused pin (in the example it is A1) down onto the extension so it sticks out when the hand is standing up.

Now you're ready to program the hand in MakeCode! Get all your code working before you insert the soft circuit into the masking tape hand. The next page tells you how.

This guide was first published on Oct 28, 2019. It was last updated on Oct 28, 2019.
This page (Create the Sequin Circuit) was last updated on Oct 21, 2020.