Monthly Archives: July 2017

Responsive Wearables: The 21st Century Mood Ring

via SparkFun Electronics Blog Posts

My Heart on My Dress is a wearable IoT project by Jingwen Zhu. This project is a great example of the marriage of engineering, design and craft — which is why we love it so much!

In developing this project, Jingwen was thinking about the psychology of clothing — how what we wear is an expression of who we are, who we want to be and how we want the world to see us. She wondered if she could develop a garment that would adapt to her emotional state daily, kind of like a mood ring. This led Jingwen to build a connected garment that visualizes her daily experiences and emotions through dynamic changing colors and patterns — all based on a real-time text analysis of her digital diary.

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How It Works

Jingwen decided to leverage her diary, which she writes in daily, as the data input for her garment. Color and patterns on the garment change in real time throughout the day based on this data. In order to realize this idea, Jingwen designed a dress with a circuit hidden inside.

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The custom-made dress is screen printed with thermochromatic ink on the outer shell. A hidden middle layer is wired with a soft circuit featuring a microcontroller, Bluetooth® module and heating pads. Jingwen also included a layer of lining in her design to protect the user’s skin from the circuit.

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The circuit is triggered when it receives data sent over low-energy Bluetooth from a custom-built diary app. The app analyzes the text from a journal entry, causing the patterns and colors to transform and change based on Jingwen’s mood.

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System Design

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In order to collect, analyze and transmit her data, Jingwen built a custom diary app, which allowed her to upload her personal entries every day.

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Once uploaded, the content is saved to a server and then analyzed. The results are sent back to her microcontroller using a Bluetooth module.

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Circuit Design

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Jingwen designed her circuit modularly. It includes a microcontroller and Bluetooth module, plus several heating pad modules. Each heating pad module has a 74HC595D shift register, eight sets of MOSFET transistors and an LED for feedback. Jingwen used term blocks to connect the modules of her circuit so that she could plug or unplug them to easily add or reduce the number of outputs. She used custom-designed circuit boards for her final product.

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Ink Design and Application

Jingwen conducted thorough research and experimentation on thermochromatic inks. She found that each ink had its own particular behaviors, which informed her application method. A thorough look at her research can be found here. Check out these mesmerizing gifs she captured of her experiments:

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I wanted to share this project for a handful of reasons. Not only is it a truly compelling idea, but it has also been executed beautifully with incredibly thorough documentation. We can really see Jingwen’s thought, design and build process through her words and images. It is often hard to describe the unique challenges of designing programmable electronic projects, which demand that makers simultaneously think about three major elements: hardware, software and design. Each of these needs to be considered throughout the project’s development. Jingwen does a great job describing what that process looks like. The transparency in her documentation speaks deeply to the open source ethos, and we are grateful to get to learn about her process and how she made this awesome project in depth.

About Jingwen Zhu

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Jingwen Zhu is an interaction designer, creative technologist and educator. Jingwen’s design engages her audience with mind-opening interactions. The techniques she creates combine traditional crafts with innovative technologies. Jingwen completed her master’s degree at New York University’s Interactive Telecommunications Program (ITP). She recently co-founded the Wearable Media Studio in New York, which is a service platform providing e-textile technologies for developing high-tech fashion products.

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HydroBot: Prototyping new modules

via Dangerous Prototypes


Matthew Reed writes:

ProtoModule is a HydroBot module designed to easily develop and test new monitoring or control functions that may someday go into a HydroBot module. It has 11 GPIO pins and the power rails broken out on a 0.1” pin header for easy breadboarding or interfacing with ribbon cables. The provided pins give access to a variety of digital and analog I/O, as well as digital communication peripherals, to allow for many flexible design options.

More info at

Tijuana Rick’s 1969 Wurlitzer Jukebox revitalisation

via Raspberry Pi

After Tijuana Rick’s father-in-law came by a working 1969 Wurlitzer 3100 jukebox earlier this year, he and Tijuana Rick quickly realised they lacked the original 45s to play on it. When they introduced a Raspberry Pi 3 into the mix, this was no longer an issue.

1969 Wurlitzer 3100

Restored and retrofitted Jukebox with Arduino and Raspberry Pi

Tijuana Rick

Yes, I shall be referring to Rick as Tijuana Rick throughout this blog post. Be honest, wouldn’t you if you were writing about someone whose moniker is Tijuana Rick?


The Wurlitzer jukebox has to be one of the classic icons of Americana. It evokes images of leather-booth-lined diners filled with rock ‘n’ roll music and teddy-haired bad boys eyeing Cherry Cola-sipping Nancys and Sandys across the checkered tile floor.

Raspberry Pi Wurlitzer

image courtesy of Ariadna Bach

With its brightly lit exterior and visible record-changing mechanism, the Wurlitzer is more than just your average pub jukebox. I should know: I have an average pub jukebox in my house, and although there’s some wonderfully nostalgic joy in pressing its buttons to play my favourite track, it’s not a Wurlitzer.

Raspberry Pi Wurlitzer

Americana – exactly what it says on the tin jukebox

The Wurlitzer company was founded in 1853 by a German immigrant called – you guessed it – Rudolf Wurlitzer, and at first it imported stringed instruments for the U.S. military. When the company moved from Ohio to New York, it expanded its production range to electric pianos, organs, and jukeboxes.

And thus ends today’s history lesson.

Tijuana Rick and the Wurlitzer

Since he had prior experience in repurposing physical switches for digital ends, Tijuana Rick felt confident that he could modify the newly acquired jukebox to play MP3s while still using the standard, iconic track selection process.

Raspberry Pi Wurlitzer

In order to do this, however, he had to venture into brand-new territory: mould making. Since many of the Wurlitzer’s original buttons were in disrepair, Tijuana Rick decided to try his hand at making moulds to create a set of replacements. Using an original button, he made silicone moulds, and then produced perfect button clones in exactly the right shade of red.

Raspberry Pi Wurlitzer

Then he turned to the computing side of the project. While he set up an Arduino Mega to control the buttons, Tijuana Rick decided to use a Raspberry Pi to handle the audio playback. After an extensive online search for code inspiration, he finally found this script by Thomas Sprinkmeier and used it as the foundation for the project’s software.

More images and video of the build can be found on Tijuana Rick’s website.


We see a lot of tech upgrades and restorations using Raspberry Pis, from old cameras such as this Mansfield Holiday Zoom, and toys like this beloved Teddy Ruxpin, to… well… dinosaurs. If a piece of retro tech has any room at all for a Pi or a Pi Zero, someone in the maker community is bound to give it a 21st century overhaul.

What have been your favourite Pi retrofit projects so far? Have you seen a build that’s inspired you to restore or recreate something from your past? Got any planned projects or successful hacks? Make sure to share them in the comments below!

The post Tijuana Rick’s 1969 Wurlitzer Jukebox revitalisation appeared first on Raspberry Pi.

BSide ACM03 plus clamp meter review and teardown

via Dangerous Prototypes


A review and teardown of a cheap Hall effect clamp meter (ACM03 Plus) from Kerry Wong:

I recently purchased a BSide ACM03 Plus clamp meter so that I could do some high current measurements for my tab welder project. This meter can be bought on eBay for around $25, which makes it one of the cheapest Hall effect clamp meters on the market that is capable of measuring both AC and DC current.
Since this is such a cheap meter, I wasn’t expecting much. But it actually feels really sturdy in hand and the construction looks reasonably solid, which is certainly a good start. It came with a nice little black pouch inside a non-descriptive cardboard box. It even includes a decent product manual.

More details on Kerry D. Wong’s blog.

Check out the video after the break.

Driving a 48-segment RGB LED bar graph with a Teensy 3.2

via Dangerous Prototypes


Glen Akins writes:

In my post Driving a SparkFun 48-Segment RGB LED Bar Graph, I stated that the hardware built there could be used to drive the LED bar graph with any combination of hardware and software that could drive one of the common 32×32 or 32×16 RGB LED matrices. Today I’m back to prove that point. In this post, I ditch the FPGA and drive the 48-segment RGB LED bar graph using a Teensy 3.2 board and the Pixelmatix SmartMatrix 3 library.

More details at Glen Akins’ blog.

Make your own Operation-style board game with Arduino

via Arduino Blog

Usually, when you think of doing “surgery” on electronics, it’s to replace a component, or maybe modifying an appliance into something different. In this case, an Arduino Nano powers Hurry, Doctor!, an updated version of the board game classic Operation meant as a middle school STEM exercise.

This game, of which creator “TrevorB23” gives an extensive explanation in his Instructables write-up, features a LEGO minifigure with cutouts inside that house obstructions such as a “mental block” and “funny bone.” As with the original, the objective is to remove these foreign bodies without touching the sides, constructed here with conductive aluminum foil tape in order to signal the Nano.

With its enhanced electronics, TrevorB23’s version adds a timing element to encourage “surgeons” to complete tasks faster, as well as doctor names and melodies that can be altered if so desired. Want to make your own game? You can follow along with his 31-step tutorial.