Introduction: Sound Reactive Lei Necklace

Hello All!

I wanted to make something fun for my daughters to wear to their school's father daughter dance. It was Hawaiian Luau themed, so there was no better way to accessorize than with a sound reactive lei necklace!

I ended up making three necklaces all together - one for me, and one for each of my daughters. By the time I made the third necklace, I had the process down and could get one put together in a about 3 hours.

The process is basically removing the original string from necklace re-stranding it with with 3 wires (power, ground, and control, + mono cord) and soldering RGB LEDs in between each flower. The fabric flowers diffuse the light nicely for a very cool, very unique look.

I had a great time making the necklaces. My daughters enjoyed the process. They both gave me great ideas , helped me test and troubleshoot, and both learned quite a bit about electronics

Without any further delay... here we go...

Oh yeah...and this is my first Instructable so be gentle...


WS8211B LEDs (strand of 60 Order Here From EBAY)

Hawaiian Leis (Order Here From Amazon)

Adafruit Gemma (Here) or Flora (Here) (Or any othersmall micro controller with JST connection)

150 mAh Lipo Battery (Order here from Adafruit)...also get a charger if you don't have one...

Wire (3 wires, 18 or 20 awg should work just fine) - use stranded as it flexes esier


Soldering Iron

Necklace wire/string (clear mono cord)

Necklace Clasp (to make taking it apart to work on easier)

Step 1: Snip Snip

1. First you will need to cut the LEDs apart....

I just used a standard pair of scissors cutting right along the line in between each LED. I used 18 LEDs on my necklace and 14 LEDs for each of my daughters' necklaces.

2. Next you will need to cut into your Lei necklace, but don't take it apart yet....

By the time I did the third necklace, I found the best way to keep track of the flowers, ensuring the proper number is on either side of the LED, is to take it apart section by section, and putting it back together, with LEDs and wire as you go.

3. Prep some wire...

Prep 18 sets of wire (Power, Ground, Signal) roughly 2 inches in length. Longer will work fine, it just makes your necklaces longer.

Strip a tiny bit of insulation off of each end wire to allow for tinning...which leads us to the next step...

Step 2: Wire and Pad Prep

1. Tin each end of wire... except for one

I left one set of cables a bit longer, and did not tin one end, and instead used DuPont connectors to make the micro controller easily removable from the necklace.

2. Tin each pad (6) of the 18 LEDs you just cut a part...yes that's 108 pads...stop reading this and get moving...

Step 3: Spacer Straw Modification

1. Cut and Weave

You are going to cut two holes in each spacer straw allowing you to almost weave the wiring in and out. Your LED will mount in between the holes, with your wiring coming in through either end of the straw, but up and through the newly cut holes.

Pull the mono cord through at the same time, not completely necesary, but the mono cord will let you disconnect the necklace and lay it flat to modify or troubleshoot later.

Now that you have your first straw ready, lets solder...

Step 4: Solder Time

1. Use a third hand....or peel the paper off and stick it to an old board or work surface

Notice the arrows...the signal only flows one way...there are plenty of other guides about these LEDs for more details...

Solder your RED wire to +5v, BLACK wire to GND, and WHITE to Din

It worked out well tinning your pads and wire a few steps your wire down onto the pad....and release.... if done properly, connection you just have to repeat it between 80 and 100 more times times :)

**Once both sides of the LED are wired, I hot glue the LED to the middle of the modified straw. This provided much better stability than the tacky tape on the back of the LED (you'll see what I mean).

2. For a much cleaner look and to protect your connections, I would use heat shrink on either side of the LED. I didn't, but if I had the chance to do it over....

3. After all your LEDs are soldered together and woven between the flowers. Its time to solder some wires to your micro controller. I used the Adafruit Flora in this example (adjust pin soldering for your specific board).

The Microphone wires are 3.3V, #10, and GND.

The LED necklace is VBATT (straight battery power), #6, and GND.

After the connections are done, it's time to add some DuPont Connections...

Step 5: DuPont Connectors Are Your Friends

Thank goodness for DuPont connectors....

I used male and female connectors to make adding and removing parts and pieces (LEDs, microphone, micro controller) simple. You can learn how to crimp on these connectors with a quick google search.

The connectors made it easy to swap out microphones and necklaces as I was testing. It will also make it easy to switch out micro-controllers for new and improved versions moving forward...

Step 6: Program Your Microcontroller

I used the Arduino IDE and the Adafruit NeoPixel Library

PROPS to Michael Bartlett for his amazing code....

GitHub Link To His Code and Project

There are numerous other examples of musical LED code that you could use here, but Michael's has some of the best transitions and color palettes I've seen. With some minor changes all 6 transitions and color pallets will work on the Flora without issue. For Gemma you will have to heavily modify Michael's code (I was able to slim it down to one palette and one transition) for it to fit. As I said before, there are other options out there that you could use on the Gemma with without issue (See @anouskadg or Adafruit).

Step 7: Upload, Test, and Glue

1. Upload the code to your microcontroller

2. Pick some music and test the your necklace. You may have to adjust the gain on the microphone and the code to get it to behave the way you want. Test, Test, and test some more.

3. Adjust the delay(30) function as you see fit. Depending on the controller I reduce the delay to 20 or 15 to get the proper response I was looking for.

4. I used hot glue and gaffers tape to attach the microcontroller, battery, and microphone to the necklace.

5. 3D printing a case would be a much better solution...there's always a next time.

Hope you had some fun. Let me know how it goes!

Lights Contest 2017

Participated in the
Lights Contest 2017