Year: 2020

Hacked Prosthesis Leads To Mind-Controlled Electronic Music

February 19, 2020 by 14 Comments

As amazing as prosthetic limbs have become, and as life-changing as they can be for the wearer, they’re still far from perfect. Prosthetic hands, for instance, often lack the precise control needed for fine tasks. That’s a problem for [Bertolt Meyer], an electronic musician with a passion for synthesizers with tiny knobs, a problem he solved by hacking his prosthetic arm to control synthesizers with his mind. (Video, embedded below.)

If that sounds overwrought, it’s not; [Bertolt]’s lower arm prosthesis is electromyographically (EMG) controlled through electrodes placed on the skin of his residual limb. In normal use, he can control the servos inside the hand simply by thinking about moving muscles. After experimenting a bit with an old hand, he discovered that the amplifiers in the prosthesis could produce a proportional control signal based on his inputs, and with a little help from synthesizer manufacturer KOMA Electronik, he came up with a circuit that can replace his hand and generate multiple control voltage channels. Plugged into any of the CV jacks on his Eurorack modular synths, he now has direct mind control of his music.

We have to say this is a pretty slick hack, and hats off to [Bertolt] for being willing to do the experiments and for enlisting the right expertise to get the job done. Interested in the potential for EMG control? Of course there’s a dev board for that, and [Bil Herd]’s EMG signal processing primer should prove helpful as well.

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Gear Up Your Gear Knowledge With Gears

February 19, 2020 by 16 Comments

Gears are fairly straightforward way to couple rotational motion, and the physics topics required to understand them are encountered in an entry level physics classroom, not a university degree. But to really dig down to the root of how gears transfer motion may be somewhat more complex than it seems. [Bartosz Ciechanowski] put together an astonishingly good interactive teaching tool on gears, covering the fundamentals of motion up through multi-stage gear trains.

Illustrating the distance traveled at different points on the disc

The post starts at the beginning – not “how to calculate a gear ratio” – but how does rotational motion work at all. The illustrations help give the reader an intuitive sense for how the rate of rotation is measured and what that measurement actually represents in the real world. From there [Bartosz] builds up to describing how two discs touching edge to edge transfer motion and the relationship of their size on that process. After explaining torque he has the fundamentals in place to describe why gears have teeth, and why they work at all.

Well written explanatory copy aside, the real joy in this post is the interactivity. Each concept is illustrated, and each illustration is interactive. Images are accompanied by a slider which lets you adjust what’s shown, either changing the speed of a rotating gear or advancing the motion of two teeth interlocking. We found that being able to move through time this way really helped form an intuitive understanding of the concepts being discussed. This feels like the dream of interactive multimedia textbooks come to life.

MNIST Clock Uses Famous Training Database

February 18, 2020 by 6 Comments

When training neural networks to recognise things, what you need is a big pile of training data. You then need a subsequent pile of testing data to verify that the network is working as you’d expect. In the field of handwriting recognition, the MNIST database is commonly used to train networks on handwritten numerals. After [Evan Pu] mentioned it would be fun to use this data to create a clock, [Dheera Venkatraman] got down to work.

The original sketch which inspired the build.

The MNIST database contains 60,000 training images, and 10,000 test images. [Dheera] selected an ESP32 to run the project, which packs 4MB of flash storage – more than enough to store the testing database at 196 bytes per numeral. This also gives the project network connectivity, allowing the clock to use Network Time Protocol to stay synchronised – thus eliminating the need for an external RTC. Digits are displayed on four separate e-ink displays, which fits well with the hand-drawn aesthetic. It also means the clock doesn’t unduly light up the room at night.

It’s a fun project that will likely draw a knowing chuckle from those working in the field of handwriting recognition. We’d love to have one on our desk, too. If you’re thinking of attempting a build yourself, check out our recent contest for more inspiration!

Everything You Wanted To Know About 3D Printing Support But Were Afraid To Ask

February 18, 2020 by 6 Comments

At the dawn of 3D printing, support structures were something to avoid. ABS is a hard substance to clear off, and the slicers did a comparatively poor job of making structures that were easy to remove. Today, supports are not a big deal and most of the slicers and materials allow for high-quality prints with supports. We were printing something with supports the other day and noticed that Cura has a support floor and roof function. Curious, we did a quick search and found this very comprehensive post about the current state of support.

With 25 topics in the table of contents, this isn’t a 3-minute read. Of course, you might wish to skip over some of the first parts if you get why you need support and understand the basic ideas. We became more interested when we reached the geometry section.

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Adding A Digital Readout To A Wood Lathe

February 18, 2020 by 6 Comments

The benefit of living in the modern era is that there are plenty of affordable machine tools on the market for the budding maker. However, to meet lower price points, products often forgo some of the nice-to-have features that make working easier. Of course, if you’ve got the skills to do it yourself, this needn’t be a problem, as [Zach] demonstrates.

[Zach] enjoyed using his wood lathe, but it didn’t come with a digital readout. Thankfully, retrofitting one was an easy, straightforward project. After a little research, a Hall effect sensor was chosen to detect the rotational speed of the lathe. The spindle was thus fitted with several magnets to trigger the sensor, allowing for higher resolution than just using a single device. An Arduino Nano was then used to monitor the output of the Hall effect sensor, displaying the rotational speed on a set of 7-segment displays. The project was then given its own custom PCB, and a nice 3D printed enclosure to fit it to the body of the lathe.

It’s a project that shows how easy it is to add functionality to basic machine tools using maker components. It also serves to demonstrate the value in giving a project a proper enclosure, to enable it to survive in a workshop environment. We’ve seen other hacky DRO mods before, too. Video after the break.

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MQTT And The Internet Of Conference Badges

February 18, 2020 by 6 Comments

Today, nearly every modern consumer device wants to connect to the Internet for some reason. From your garage door opener to each individual smart bulb, the Internet of Things has arrived in full force. But the same can’t be said for most of our beloved conference badges. Wanting to explore the concept a bit, [Ayan Pahwa] set out to create his own MQTT-connected badge that he’s calling CloudBadge.

As this was more of a software experiment, all of the hardware is off-the-shelf. The badge itself is an Adafruit PyBadge, which doesn’t normally have any networking capabilities, but does feature a Feather-compatible header on the back. To that [Ayan] added a AirLift FeatherWing which allows him to use the ESP32 as a co-processor. He also added a strip of NeoPixel LEDs to the lanyard, though those could certainly be left off if you’re not looking to call quite so much attention to yourself.

The rest was just a matter of software. [Ayan] came up with some code that uses the combined hardware of the PyPadge and ESP32 to connect to Adafruit.io via MQTT. Once connected, the user is able to change the name that displays on the screen and the colors of the RGB LEDs through the cloud service. If you used something like this for an actual conference badge, the concept could easily be expanded to do things like flashing the badge’s LEDs when a talk the wearer wanted to see is about to start.

The modern conference badge has come a long way from simple blinking LEDs, offering challenges that you’ll likely still be working on long after the event wraps up. Concerns over security and the challenge of maintaining the necessary infrastructure during the event usually means they don’t include networking features, but projects like CloudBadge show the idea certainly has merit.

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Foxie Clock Works In Two Ways

February 18, 2020 by 22 Comments

Nixie tubes are a hacker favorite for their warm glow and elegant, mid-century numerals. They’re also a pain to drive, demand high voltages, and aren’t exactly cheap and easy to come by. Never mind, for there are other ways to go – as [Alex Fox] demonstrates with the Foxie Clock.

The Foxie clock gets its name from its creator, in a portmanteau with the famous Nixie tubes. Rather than going with gas-filled extravagances, instead, acrylic pieces are engraved with similar numerals to the old technology. These are edge-lit by what appear to be WS2812 addressable LEDs, or similar. This led [Alex] to realise that the clock could also be configured to display in an alternate mode, instead creating numerals using the individual RGB LEDs as segments behind a frosted acrylic panel.

It’s a versatile project that ended up working as a clock in two unique yet appealing ways. We’re a sucker for a quality retro typeface, so are firmly on Team Edge-Lit, but sound off in the comments which you think is best. Others have attempted similar builds, too. And remember, if you can’t get your hands on one part, it always pays to experiment!