Create a color-changing sweatshirt with a potentiometer and GEMMA

Stay warm while looking cool! 

While we’ve covered a number of Becky Stern’s slick wearable creations in recent months, the timeliness of this one couldn’t be better for our friends in the Northeast as they battle these bitter cold months. Thanks to her latest tutorial, Makers can now easily create their own color-changing NeoPixel hoodie using a soft potentiometer, conductive thread, some tiny LEDs and an Adafruit GEMMA (ATtiny85).


Conductive thread is used to connect the potentiometer to the wearable platform board, which is sewn to the zipper on the front of the sweatshirt. This allows for the use of the drawstring to perform a sliding action. The sensor’s ribbon was divided in half, leaving two pieces: one for the pull tab, the other to slide along.


“The yarn in the sensor has a high resistance that GEMMA can measure with its analog input. The charm moves along its length, changing the amount of yarn connected to the input,” Stern explains.

Stern notes that a Maker could also couple a temperature control action of zipping/unzipping the hoodie with the LED color-changing effect. However, for simplicity sake of the demonstration, she decided to keep them separate.


With a simple Arduino sketch and stitching of the NeoPixels tasked with altering colors, you’re just about ready to go. The code uses the changing value of the slide sensor to adjust the blinking speed of GEMMA’s onboard LED. Slide the sensor and watch the LED blink faster or slower.

Before completing the project, a Maker must cut a small hole in the upper inside edge of the hoodie’s front pocket, and thread through a JST extension wire for the AAA battery pack. Store the batteries inside the pocket, and run the extension cable up through the front facing to plug into GEMMA’s JST port. And, voila!


Ready to give your hoodie some special effects for a cold winter night? You can find an entire step-by-step breakdown of the build here. Meanwhile, you can also check out some of Stern’s most wow-worthy wearables here.

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