Hackaday Prize Semifinalist: Portable A/C

Many people with Multiple Sclerosis have sensitivity to heat. When the core body temperature of an MS sufferer rises, symptoms get worse, leading to fatigue, weakness, pain, and numbness. For his entry to the Hackaday Prize, [extremerockets] is finding a solution. He’s developing a wearable, personal cooling device that keeps the wearer at a comfortable temperature.

The device is based on a wearable shirt outfitted with small tubes filled with a cooling gel. This setup is extremely similar to the inner garments worn by astronauts on spacewalks, and is the smallest and most efficient way to keep a person’s core body temperature down.

Unlike a lot of projects dealing with heating and cooling, [extremerockets] isn’t working with Peltiers or thermoelectric modules; they’re terribly inefficient and not the right engineering choice for something that’s going to be battery-powered. Instead, [extremerockets] is building a miniature refrigeration unit, complete with a real refrigeration cycle. There are compressors, valves, and heat exchanges in this build, demonstrating that [extremerockets] has at least some idea what he’s doing. It’s a great project, and one we can’t wait to see a working prototype of.

The 2015 Hackaday Prize is sponsored by:

Make Your Own Transparent Whiteboard

Now this is seriously cool. Beyond seeing it in movies, having a transparent whiteboard that lights the ink up is absolutely awesome and pretty darn unique. [Andrew McNeil] shows us how — and it’s pretty simple too!

As an avid YouTuber, [Andrew] often has to explain things by drawing out diagrams and what not. If you’ve ever tried to film yourself doing this, you’ll know it’s not easy. So what if you could use the whiteboard like you normally would? And that whiteboard is also the window of which you, the audience, watches through? It’s really quite brilliant, and already in use for some teaching methods.

But wait, are we talking about literally using a glass window to write on? Well… kind of. But the trick is to have the glass edge-lit using LEDs. Doing so will literally make your dry erase markers glow. It practically looks like a neon sign.

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A Sunflower Heat Engine

Looking for a cool science experiment to do with the kids? Why not build a type of heat engine that resembles a sunflower? [Steve] from Rimstar.org shows us how!

It’s actually a pretty ingenious little project. Using metal foil scraps from a coffee bag, [Steve] created a perfectly balanced wheel that looks kind of like a sunflower. When the foil petals come close to heat they try to expand, but much like a bimetal strip, the materials making up the packaging expand at different rates to straighten the heated petal. This moves the center of gravity of the wheel off-axis, causing a rotation. As the wheel spins, the foil petal cools off, and another one is heated, creating continual movement — at least until the heat supply is taken away!

It’s a lot of work to get the balance just right, but thanks to an ingenious axle design it’s pretty easy to make adjustments. The wheel actually floats on a nail with its point stuck to a magnet, and the other end is suspended by a series of magnets. It’s pretty much as close to a friction free axle as you can get!

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Firmware Factory: Bit Fields vs Shift and Mask

Working with embedded systems usually involves writing code which will interface with hardware. This often means working on the register level. It doesn’t matter if we’re talking about a UART, an analog to digital converter, an LCD controller, or some other gizmo. Sooner or later, you’re going to have to break out the datasheets and figure out how to talk to an external device. To succeed at this you must become a master of bit manipulation.

Hardware designers don’t like wasting space, so modes, settings and other small pieces of information are often stored as packed bits. Our processors usually access things a byte (or a word) at a time, so what is the best way to handle this? Like so many other topics in software engineering, there are multiple ways to skin this cat. In C (and its derivatives) there are two major options: shift and mask, and bit fields.

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Hacklet 72 – Burning Man Projects

Burning Man is almost here! In just a few days, artists, hackers, makers, and engineers will converge on the Black Rock Desert in northern Nevada. They’ll endure the heat, the dust, and possibly a few bugs to create one of the largest outdoor art festivals in the world. Every year, the playa is covered with art cars, giant rolling barges, and fire-breathing animals covered in RGB LEDs. With so many projects to work on, it’s no surprise that quite a few Hackaday.io members (and Hackaday staffers) are burners. This week’s Hacklet is about some of the best Burning Man projects on Hackaday.io!

thedeepWe start with [David Nghiem] and “The Deep” – DC’s Sonic Jellyfish Art Cart. There’s just something calming about a watching a luminescent jellyfish floating serenely through the dark ocean. [David] and his team are recreating that effect in the desert with The Deep. They’re hanging a giant jellyfish in front of a golf cart. The medusa will be festooned with yards of silk and other types of fabric to create a flowing effect. Lighting will come from 8 RGB LED strips, controlled by 15 Teensy LCs. The Teensys will keep the lights flashing to the beat of the music. Burners can dance inside the sculpture, because this jellyfish thankfully has no sting.

anglerfishBicycles are the preferred mode of personal transportation at Burning Man. As you might imagine, it can be pretty hard to find your bike among all the other parked cycles. [Bob Baddeley] has made this a bit easier with Anglerfish for Bikes. Real anglerfish have an illicium, which is a stalk with a lighted tip that hangs just in front of their mouth. The bioluminescent light lures prey to the fish. [Bob] is using an RGB LED illuminated ball to lure him to his bike. This anglerfish started life as a blinky globe from Amazon. [Bob] removed the original electronics and replaced them with a Bluetooth radio on his own custom PCB. A simple press of a button gets the ball shimmering and blinking, leading [Bob] to his ride.

danceNext up is [Jeremy] with Interactive Disco Dance Floor. Inspired by Saturday Night Fever and the music video for Billy Jean, [Jeremy] is creating a dance floor that responds to those dancing on it. The floor is lit by 80 meters of 5050 RGB LEDs, controlled by ATmega168s. The ATmega168’s are connected to a capacitive sensor made up of a chicken wire grid. The system is sensitive enough to pick up feet even when wearing thick motorcycle boots. All the processors connect to a central computer via an RS-485 network. This allows the computer to take over and drive pre-programmed patterns to the floor. The PC side code is written in JavaScript, so it’s easy to modify.

jacketFinally, we have Hackaday.io’s own [Jasmine] with Glow Jacket. Walking around at night in Black Rock City can be dangerous. People running from party to party, high cyclists flying across the playa, you never know who might run into you! Having something to make sure you’re visible is a great start of a project. Keeping warm through the cold nights in the desert would be an added bonus. [Jasmine] sewed 32 feet of electroluminescent (EL) wire onto the back of a black parka. The wire ran to two AA battery-powered inverters hidden in the jacket. The hardest part turned out to be sewing all that EL wire to a jacket. Once all the stitching was done though, her husband [Ben] glows like a beacon in the night.

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Burners unite! [Jasmine] has set the Hacker Burners project page as a meeting place for all burners and fans of Burning Man. If you’re interested, join up! If you’d like to see more Burning Man projects, I’ve got you covered with our new Burning Man project list. If I missed your project, don’t hesitate to drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Cheap Function Generator Teardown and Improvement

In general, you get what you pay for, and when [Craig] picked up a cheap function generator off eBay, he didn’t expect much from it. But as he shows us in his blog post and a series of videos below, while the instrument lived down to his expectations, he was able to fix it up a bit.

Having spent only $100USD for the MHS-5200A, [Craig]’s adventure is a complete teardown and analysis of the function generator. While it sort of lives up to its specs, it’s pretty clear that some design decisions resulted in suboptimal performance. At higher frequencies and higher amplitudes, the sine wave output took on a markedly non-sinusoidal character, approaching more of a triangle waveform. The spectrum analyzer told the tale of multiple harmonics across the spectrum. With a reverse-engineered schematic in hand, he traced the signal generation and conditioning circuits and finally nailed the culprit – an AD812 op-amp used as the final amplifier. An in-depth discussion of slew rate follows in part 2, and part 3 covers replacement of the dodgy chip with a better selection that improves the output signal. We’re also treated to improvements to a low-pass filter that fixed a nasty overshoot and ringing problem with the unit’s square wave function.

If hacking the MHS-5200A seems a bit familiar to you, that’s because we covered another reverse-engineering exploit of it recently. That hack of the serial protocol of the instrument was by [WD5GNR], also known as Hackaday’s own [Al Williams]. Cheers to both [Craig] and [Al] for showing us what you can do with a hundred bucks and a little know-how.

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Building a Business Around Generative Design and Marvels of 3D Printing

Generative design is a method of creating something by feeding seed data into an algorithm. It might be hard at first to figure out how someone would build a business around this, but that’s exactly what Nervous System has been doing with great success. The secret is not only in the algorithm, but in how they’re bringing it to life.

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