Introduction: LED Broken Heart Bracelet

About: I used to teach middle school science, but now I run my own online educational science website. I spend my days designing new projects for students and Makers to put together.

A fun valentines project with conductive thread and LEDs. This bracelet helps beginners learn how circuits work and operate. This soft-circuit bracelet only is light up when you are wearing it due to the fastened snap.

This project is designed for beginner students. It requires basic knowledge about circuits and sewing. You can find the kit at Brown Dog

Difficulty: Easy

Cost: Low

Time: 35- 45 minutes

Step 1: Materials

All parts for this project, as well as beginning sewing kits, can be found at


  • Needles
  • Scissors
  • White thread
  • Safety pins or regular pins


  • Felt
  • Snap Parts
  • Conductive Thread
  • Battery Holder
  • Battery
  • LEDs: Amber

Step 2: Instruction Video

For those of you who prefer video, watch this.

Step 3: Cut the Felt.

Cutting the Bracelet

  1. Cut the felt the width you want your bracelet to be, about 1 1/2" wide.
  2. Measure the length to fit your wrist so the ends meet. It may be trimmed even shorter later, but to begin the ends shouldn't overlap.

Cutting the heart pieces

  1. Cut out the paper heart template pieces.
  2. The smaller pieces are templates for the white felt, the larger ones for the purple.
  3. Pin the paper templates onto the felt and cut them out.

Step 4: Layout Parts

Layout your parts as shown above.

Notice the positive '+' and negative '-' symbols on the drawing. Each of the electrical components has a correct orientation, labeled on the drawing Each line connecting the pieces is a continuous piece of conductive thread carrying electricity. This is a series circuit, as the LED is in line with battery. The snap acts as the switch, breaking the power connection when it is opened.

Step 5: Non-Conductive Sewing.

Threading the needle

  1. Pull a long length of thread, a bit longer than the length of your arm.
  2. Thread one end through the needle eye. If you have difficulty, make sure you have good lighting and a freshly cut thread end. Sometimes wetting the needle eye and the thread end can help.
  3. Pull the thread through the needle till the ends meet.

Tying a knot

  1. Wrap the end of the thread around your index finger so the ends meet just under your thumb.
  2. Roll the thread between your thumb and index finger. This will wrap the end of the thread through the loop on your finger several times.
  3. Pull the two ends of your thread to tighten the knot.
  4. Trim the excess thread after the knot as needed.

Sewing the heart pieces together

  1. Line up the pieces as shown.
  2. Sew them together with big stitches, starting the needle on the back.
  3. End your stitches on the backside.

Knot the end of the thread

  1. To tie a knot, pierce only the back purple piece of felt with the thread
  2. Pull the thread partially through, forming a loop.
  3. Run the needle through the loop several times from the same direction. This will wrap the thread around itself.
  4. Pull on the thread to close the knot.
  5. Trim the thread with a scissors.

Sewing heart pieces to bracelet

  1. Arrange the heart halves at a 45 deg angle as shown.
  2. Attach the heart halves to the bracelet with a safety pin
  3. Wrap around your wrist and check the length is correct. If it is too big it will fall off your hand. Trim the bracelet as needed.
  4. Take a length of thread and sew from the backside. Be careful to only penetrate the pink bracelet and purple heart piece so the stitches do not show on the front.
  5. Create a knot on the end as shown and trim.

Step 6: Conductive Thread - Battery

We will start with the negative end of the battery holder in the center.

  1. Pull a long length of conductive thread off the spool and thread it through the needle. This may be difficult as the conductive thread is thick. Cut a new clean end if it gets too frayed when you try to thread the needle.
  2. Tie a knot on one end of the conductive thread. DO NOT double up like with the regular white thread.
  3. From the backside, pierce the bracelet and one of the battery tabs with the hole. Pull the knot flush with the back of the bracelet.
  4. Pierce the bracelet just outside the battery tab.
  5. Circle the thread around the battery tab 2-3 times to make a secure connection.
  6. Make large stitches toward the heart half on the right, ending with the needle and thread on the back side. If you like you may add a decorative arrow as shown.
  7. DO NOT make a knot and cut the thread, we will connect the conductive thread to the snap in the next step.

Step 7: Conductive Thread - First 'in-y' Snap

  1. Wrap the heart halves around so they line up
  2. Fit the 'in-y' snap where the pieces overlap in the center. This is where the snap will go.
  3. Hold the snap in place and secure it to the bracelet by running the conductive thread through all the holes. End the stitching on the backside.
  4. Tie a knot in the thread as previously shown and trim it.

You have now connected the negative side of the battery terminal to the 'in-y' snap, making half of the circuit.

Step 8: Conductive Thread - LED

Next we will attach the negative end of the battery to the negative end of the LED.

  1. Thread another long length of conductive thread through the needle and tie a knot on one end.
  2. Starting on the backside, loop the thread around the battery holder negative end several times to attach it to the bracelet.
  3. Use large stitches to run the conductive thread toward the center of the other heart. End on the backside. If you like, you may use the thread to create the feather fletching on the end of the arrow piercing our heart.
  4. Look on the back side of the LED for the '-' negative symbol.
  5. Connect the negative end of the LED to the bracelet by looping the conductive thread through the hole and felt several times. End your loops on the backside.
  6. Create a knot in the end of the thread as shown previously and trim it with the scissors.

Step 9: Conductive Thread - Final Snap

Finally we will connect the 'out-y' snap to the positive end of the LED.

  1. Thread a shorter length of conductive thread through the needle and knot one end.
  2. Starting on the back, loop around the positive end of the LED to attach it to the heart.
  3. DO NOT tie a knot or cut the conductive thread yet.

Next we need to figure out where the 'out-y' snap goes.

  1. Overlap your hearts how the finished bracelet will be to determine where the 'out-y' snap will go. It will probably be somewhere under the LED.
  2. Notice if the snap touches the conductive thread under the negative end of the LED. If it does not, sew the 'out-y' snap to the back of the heart with the conductive thread, making sure it does not show on the front.
  3. If the snap is touching the negative end of the LED (as shown above), we have a problem. This would create a short circuit between the positive and negative ends of the LED. Electricity is lazy and takes the easiest path. If it can bypass the LED on its way to and from the battery, it will, which won't make the LED light up. To fix this we will add an insulator.
  4. Take a small square of felt that is double the size of the snap and sew the 'out-y' snap to the felt with the conductive thread. Tie a knot in the end and trim the conductive thread.
  5. Fold the small piece of felt underneath the snap, so that it forms an insinuative barrier between the snap and the heart. Trim any excess felt.
  6. Attach the felt and snap to the back of the heart with regular thread, taking care so the white thread does not show on the front.

Your circuit is done!

Step 10: Battery and Final Trim

To insert the battery, hold it positive side up and slide it under the 3 prongs. Push it down till it is secure.

Wrap your bracelet around and secure the snap. The LED should light!

Trim the excess felt as shown so the white heart looks continuous.

Like this project? You can find supplies and more projects like it at Brown Dog Gadgets.

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