Coaxing Water From Desert Air

April 4, 2018 by 75 Comments

From the windtraps and stillsuits of Dune’s Arrakis, to the moisture vaporators of Tatooine, science fiction has invented fantastic ways to collect the water necessary for life on desert worlds. On Earth we generally have an easier go of it, but water supply in arid climates is still an important issue. Addressing this obstacle, a team of researchers from MIT and the University of California at Berkeley have developed a method to tease moisture out of thin air.

A year after the team first published their idea, they have successfully field-tested their method on an Arizona State University rooftop in Tempe, proving the concept and the potential for scaling up the technology. The device takes advantage of metal-organic framework(MOF) materials with high surface area that are able to trap moisture in air with as little as 10% humidity — even at sub-zero dewpoints. Dispensing with the need for power-hungry refrigeration techniques to condense moisture, this technique instead relies on the heat of the sun — although low-grade heat sources are also a possibility.

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HairIO: An Interactive Extension Of The Self

March 29, 2018 by 19 Comments

Most of what we see on the wearable tech front is built around traditional textiles, like adding turn signals to a jacket for safer bike riding, or wiring up a scarf with RGB LEDs and a color sensor to make it match any outfit. Although we’ve seen the odd light-up hair accessory here and there, we’ve never seen anything quite like these Bluetooth-enabled, shape-shifting, touch-sensing hair extensions created by UC Berkeley students [Sarah], [Molly], and [Christine].

HairIO is based on the idea that hair is an important part of self-expression, and that it can be a natural platform for sandboxing wearable interactivity. Each hair extension is braided up with nitinol wire, which holds one shape at room temperature and changes to a different shape when heated. The idea is that you could walk around with a straight braid that curls up when you get a text, or lifts up to guide the way when a friend sends directions. You could even use the braid to wrap up your hair in a bun for work, and then literally let it down at 5:00 by sending a signal to straighten out the braid. There’s a slick video after the break that demonstrates the possibilities.

HairIO is controlled with an Arduino Nano and a custom PCB that combines the Nano, a Bluetooth module, and BJTs that drive the braid. Each braid circuit also has a thermistor to keep the heat under control. The team also adapted the swept-frequency capacitive sensing of Disney’s Touché project to make HairIO extensions respond to complex touches. Our favorite part has to be that they chalked some of the artificial tresses with thermochromic pigment powder so they change color with heat. Makes us wish we still had our Hypercolor t-shirt.

Nitinol wire is nifty stuff. You can use it to retract the landing gear on an RC plane, or make a marker dance to Duke Nukem.

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This Big, Bright Seven-Segment Display Is 3D-Printable

March 18, 2018 by 16 Comments

Seven-segment LED displays have been around forever, it seems, and the design is pretty optimized by now. Off-the-shelf units are readily available in all sorts of sizes and colors, but if you want a really big display, you might have to roll your own. Scaling up the size doesn’t necessarily mean you have to scale up the complexity, though, if this light-pipeless jumbo seven-segment LED display is any indication.

It’s clear that [Fran Blanche] has a thing for collecting and building oddball numeric displays, like this cathode ray tube Nixie knockoff or her Apollo DSKY electroluminescent display. Her plus-size seven-segment display is far less complicated than either of those, and that’s by design; [Fran] wanted something that was 3D-printable as a single part, rather than an assembly with light pipes and diffusers. To that end, the display is just a pair of X-shaped dividers stacked on top of each other behind the display’s face. They dividers form six triangular compartments and a diamond shaped one, with each compartment opening into a segment-shaped window. One LED goes in each triangular compartment, while the double-sized diamond space gets two. That’s it — the LEDs light up the inside of each compartment to turn on the appropriate segments. Watch it in action below.

The display still needs some tweaking, but it’s big and bright and has a large acceptance angle. What’s more, it’s scalable — imagine a display the size of a sheet of plywood using LED light bulbs. We’re looking forward to [Fran]’s improvements and her next display project, which appears to use hot glue as a light pipe.

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Repairs You Can Print Contest: Meet The Winners

February 28, 2018 by 21 Comments

Six weeks ago, we asked you to show us your best 3D printed repairs for a chance to win $100 in Tindie credit and other prizes. You answered the call with fixes for everything from the stuff everyone has, like zippers and remotes, to the more obscure stuff, like amazing microscopes scavenged from dumpsters.

It was hard to whittle down the entries we received into the top 20 because you came up with so many awesome fixes. A few of them had us thinking hard about the definition of repair, but are brilliant in their own way.

So without further ado, we are pleased to announce the winners of our Repairs You Can Print contest. We also want to give honorable mention to those projects that wowed us with ingenuity.

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Building A Portable Solar Powered Spot Welder: Charging Supercapacitors

February 28, 2018 by 48 Comments

Before Lunar New Year, I had ordered two 3000 F, 2.7 V supercapacitors from China for about $4 each. I don’t actually remember why, but they arrived (unexpectedly) just before the holiday.

Supercapacitors (often called ultracapacitors) fill a niche somewhere between rechargeable lithium cells and ordinary capacitors. Ordinary capacitors have a low energy density, but a high power density: they can store and release energy very quickly. Lithium cells store a lot of energy, but charge and discharge at a comparatively low rate. By weight, supercapacitors store on the order of ten times less energy than lithium cells, and can deliver something like ten times lower power than capacitors.

Overall they’re an odd technology. Despite enthusiastic news coverage, they are a poor replacement for batteries or capacitors, but their long lifespan and moderate energy and power density make them suitable for some neat applications in their own right. Notably, they’re used in energy harvesting, regenerative braking, to extend the life of or replace automotive lead-acid batteries, and to retain data in some types of memory. You’re not likely to power your laptop with supercapacitors.

Anyway, I had a week-long holiday, and two large capacitors of dubious origin. Sometimes we live in the best of all possible worlds. Continue reading “Building A Portable Solar Powered Spot Welder: Charging Supercapacitors” →

Repairs You Can Print: A Turn Signal Switch For A Chevy Corvair

February 17, 2018 by 14 Comments

Running a classic car is often an easier prospect than a more recent model, as the mechanical parts have a tendency towards commonality between models, simplicity, and maintenance using basic tools. However assuming some level of parts availability for your model it is not usually the running gear that causes headaches. Instead, it is the smaller and less durable parts, the little plastic pieces that formed vital components but have not been manufactured for decades. These are the parts for which the advent of accessible 3D printing has been a revelation, suddenly the owner of a wreck need only to have basic CAD skills to deliver the goods.

A Chevy Corvair (not [Ken]'s one). Greg Gjerdingen [CC BY 2.0].
A Chevy Corvair like [Ken’s]. Greg Gjerdingen [CC BY 2.0].
[Ken] has a ’63 Chevy Corvair, an attractively-styled motor notable for its rear-engined layout and air-cooled engine. And it seems his car is plagued by the same issue as all other early models, a failure of its turn signal mechanism. The version fitted to later cars is a vastly superior replacement, but required some modification to fit his ’63 model. Even after modifcation, the updated part had a plastic component that was too long for his steering wheel. Would he grind down the later part to fit, or go with a later wheel? No, he turned to Google Sketchup, and 3D printed a replacement of the correct size. He does admit that it’s not perfect as the signals cancel at a slightly different point from where they should, but since he’s been using it for four years it appears to have done the job.

We wish [Ken] every success with his Corvair, and indeed can’t help envying him a little for owning it. Some of us have been known to dabble in older metal, too.

This is an entry in Hackaday’s

Repairs You Can Print contest

The twenty best projects will receive $100 in Tindie credit, and for the best projects by a Student or Organization, we’ve got two brand-new Prusa i3 MK3 printers. With a printer like that, you’ll be breaking stuff around the house just to have an excuse to make replacement parts.

 

Pulling Music Out Of Thin Air With A Raspberry Pi

February 15, 2018 by 1 Comment

Pianos are great instruments, but being rather heavy and requiring a fair amount of space they are certainly not known for their convenience. Sure, there are more portable varieties available, but they rarely resemble the elegance and classiness of a grand piano. One option is of course to build a downscaled version yourself — and since you’re already customizing the instrument, why stop at the way you play it. [2fishy] didn’t stop there either and ended up with a wooden, space friendly, light controlled piano housing a Raspberry Pi.

Inspired by the concept of a laser harp, [2fishy] followed the same principle but chose a simpler and safer alternative by using LEDs instead. For each playable tone, a LED is mounted opposite a light dependent resistor, creating an array of switches that is then connected to the Raspberry Pi’s GPIO pins. A Python script is handling the rest, polling the GPIO states and — with a little help from pygame, triggering MIDI playback whenever the light stream is interrupted.

There are enough LED/LDR pairs to play one full octave and have some additional control inputs for menu and octave shifting. This concept will naturally require some adjustments to your playing — you can get an idea of it in the demonstration video after the break. And if this design is still not the right size for you, or if you prefer to play in total darkness, this similar MIDI instrument using ultrasonic distance sensors could be of interest.

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