Geometric LED matrix pendant with fortune-telling talent


Sometimes, you want to be subtle, and sometimes you want to be loud. And sometimes, you just want to ask the Fortunes a simple yes or no question. 

Now you can do all that with this modern necklace that looks subtle and simple at first glance, and then turns into a versatile light show with a touch or a tap. It even reaches into the random number universe to answer your categorical questions when you touch it!

This necklace is programmed with CircuitPython and made with the adorable DotStar LED Matrix, powered by the ItsyBitsy nRF52840 so you can easily customize your style over Bluetooth using the Adafruit Bluefruit Connect App!

The front panel is a fascinating black LED acrylic material, which stays opaque until LED lights shine through. It also has a brass piece that acts as a capacitive touch button and a rechargeable battery thanks to the LiPo backpack. 

The ItsyBitsy and LiPo battery are all housed inside a case that can be worn behind your neck, and the necklace is connected via a USB micro-B connector, so you can change the electronics housing if you desire. There is a lot of room for customization here to really make this project your own!

This project requires quite a bit of soldering, so here are some excellent guides if you want to brush up on the basics:

You'll also need to either laser cut or 3D print the both the pendant frame and electronics case. The black LED acrylic can be milled or laser cut to a simple square shape.

Parts for Pendant

Hand holding small Adafruit DotStar High Density 8x8 Grid - 64 RGB LED Pixel Matrix
Do not eat this LED grid just because it is so colorful and bite-sized! This is the tiniest little LED grid we could make, with 64 full RGB color pixels in a square that is only...
In Stock
LED RGB matrix 10.2" x 5.1" with "Adafruit Industries LED Matrix" text showing, and LED acrylic slowly covering to make it nicely diffused
 nice whoppin' rectangular slab of some lovely black acrylic to add some extra diffusion to your LED Matrix project. This material is 2.6mm (0.1") thick and is made of...
In Stock
1 x Brass kite shape
For capacitive touch sensing (choose whatever shape you like!)
1 x Small zip tie
Secure the wires on top of the pendant
1 x Double sided foam tape
Strong enough to stick to acrylic and PCBs
1 x Super glue
Get the gel kind so you have a few more seconds before it dries
1 x Jump ring
Optional. Makes it easy to attach the pendant to some thread
1 x Enameled copper wire
Optional. Use as a thin wire to connect the brass shape to the board.

Parts for Electronics + Power

Angled shot of Adafruit ItsyBitsy nRF52840 Express - Bluetooth LE.
What's smaller than a Feather but larger than a Trinket? It's an Adafruit ItsyBitsy nRF52840 Express featuring the Nordic nRF52840 Bluetooth LE...
In Stock
Lithium Ion Polymer Battery 3.7v 420mAh with JST 2-PH connector and short cable
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This...
Out of Stock
1 x USB DIY Slim Connector Shell - MicroB Plug
To connect the necklace to the ItsyBitsy and power
1 x LiIon/LiPoly Backpack Add-On
Power the ItsyBitsy via a rechargeable battery
1 x Slide Switch
SPDT switch to control power when battery is connected
1 x Embroidery threads
Gold thread to wrap necklace cord and allow braiding of wires
1 x 1M (or greater) ohm resistor
For the capacitive touch pin
1 x Double sided thin tape
For securing the battery
1 x Brass teardrop shape
Optional. To decorate the electronics case with!

This guide was first published on Dec 22, 2020. It was last updated on Jul 17, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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