The Gathering: Shanghai’s Hackaday Community

March 24, 2014 by Aleksandar Bradic 10 Comments

It happened! The Gathering crossed the Pacific and landed in Shanghai on Thursday, March 20th. It took place at the venue ironically called ‘Abbey Road’ (it’s the only one we could find on such a short notice) and more than 150 people showed up. The whole scene had a huge Chatsubo feel too it – an eclectic mix of local and expat hackers and engineers, professors, students and all sorts of industry mercenaries from around the world. And everyone with skull-and-wrenches t-shirt or a sticker on.

I can only imagine what Chinese police would think if they happened to drop by. Not to mention if they asked how in the world did all these ‘anarchist’ t-shirts enter the country.

But that’s another story…

We met a lot of exciting people and heard all sorts of weird tales, such as the (off-the-record) one about the real reasons behind certain well-known laptop manufacturer’s batteries bursting into flames. We also got a lot of great advice on smuggling electronic components out of China and other everyday tips & tricks.

My favorite conversation was with [Alexander Klink] on his research in Denial of Service attacks using algorithmic complexity of collision resolution in (a priori known) hash functions. Though the original paper is more than two years old, its takeaways can still have a huge impact on all sorts of software and hardware devices out there.

The general theme of the night was how exciting it is to live in a place like Shanghai, where rapid urban growth and access to manufacturing resources meets a blossoming technology and art scene. It is even more so thanks to places like Xin Che Jian, which make being a “hacker” a socially acceptable thing on the other side of the Great Firewall.

That said, reading all of Hackaday content still requires a proxy.

3 Cheap Hood/Hatchback/Topper Mods To Save Your Noggin

March 24, 2014 by Todd Harrison 32 Comments

This is a mod more than a hack but any time you can alter original equipment to maintain its usability is a win-win scenario for you and the environment. Everyone has or knows somebody that has a vehicle and most vehicles nowadays have some type of hatchback or hood where the support solution is gas filled struts. Inevitably these gas filled struts fail with age and the failure is accelerated in hotter or colder climates. If you ever had to replace these items you know they can cost a minimum of $20 to as much as $60 a piece. Most vehicles require two, four or even eight of these costly little devices.

[Brian] from Briansmobile1 YouTube channel documented three simple and low cost solutions. We all probably know of the vice clamp solution but that is cumbersome and still an expensive solution which is not always very handy or fast. Another solution is to cut a piece of rubber hose in a kind of special way so it is easy to put on and take off the shaft and dangles from a string so it’s always available. The best solution was to use a hitch pin also connected to a string or wire. To make the hitch pin work you have to grind a couple of notches on either side of the lift shaft at just the right spot so the pin can be snapped on and prevent the shaft from retracting at your selected height.

We are sure these solutions will come in handy at some time in most everyone’s driving career. Just after the break we will link to all three of [Brian’s] handy videos on gas strut fix solutions. And if you do your own automotive repair we can definitely recommend [Brian’s] channel of over 600 vehicle repair and maintenance videos which normally come with a dose of philosophy and humor.

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Embeded Sieve Of Eratosthenes: Hunting Primes On ARM

March 24, 2014 by Mike Szczys 16 Comments

Embeded Sieve of Eratosthenes

I ended up with just enough time over the weekend to pull together a quick project. I implemented the Sieve-of-Eratosthenes on an ARM chip.

If you haven’t heard of the Sieve of Eratosthenes then you really need to work your way through Project Euler. That’s where I first learned about this method of finding prime numbers. You begin with a list of all numbers, find a prime, then remove all multiples of that prime from the list. The real trick with doing it on a microcontroller is to figure out how to store a large list of numbers in a limited space. The gist of my method was to use a boolean array (I call it a bit-packed array but that may be the wrong way of saying it). The details are found in my project linked at the top.

‘Why?’ is almost always the wrong question to ask around here. But in this case, I did this because I wanted to try out the Bit Banding functionality of the ARM core. These chips have alias addresses that map to a single bit in the SRAM and also some of the peripheral registers. This allows read or write access for a single bit using a single instruction. Turns out that one side effect of 32-bit architecture is having addresses to burn.

Mechanical Iris Will Make You Want A Laser Cutter Even More

March 24, 2014 by James Hobson 35 Comments

Mechanical irises are very intricately designed mechanisms that are mesmerizing to see in action — and if you have a laser cutter, you could make one in less than 10 minutes.

Our “Teacher of Science”, Instructables’ user [NTT] has revised a previous Instructables design on a mechanical iris to improve it. The original design used three layers of components and dowel pins for every joint. What [NTT] has done is reduced this to two layers, and eliminated half of the pins required by designing clever circular cutouts. The result is a very slick mechanical iris that is very easy and quick to build — provided you have the tools.

Stick around to see the original iris open and close — unfortunately there’s no video of the new design — but we think you can imagine the differences.

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Monitoring Your Gas Consumption With A JeeNode And A NRF24L01+

March 23, 2014 by Mathieu Stephan 15 Comments

[Sven337] just blogged about a gas consumption monitoring setup he finished not long ago. As his gas meter was located outside his apartment and nowhere near any electrical outlet, a battery-powered platform that could wirelessly send the current consumption data to his Raspberry Pi was required. His final solution therefore consists of a JeeNode coupled with the well known nRF24L01+ wireless transmitter, powered by 3 supposedly dead alkaline batteries.

[Sven337] carefully looked at the different techniques available to read the data from his meter. At first he had thought of using a reflective sensor to detect the number 6 which (in France at least) is designed to reflect light very well. He then finally settled for a magnetic based solution, as the Actaris G4 gas meter has a small depression intended for magnetic sensors. The PCB you see in the picture above therefore has a reed sensor and a debug LED. The four wires go to a plastic enclosure containing the JeeNode, a couple of LEDs and a reset switch. Using another nRF24L01, the Raspberry Pi finally receives the pulse count and reports it to an eeePC which takes care of the storage and graphing.

Humble Beginnings Of A Pick And Place Machine

March 23, 2014 by James Hobson 10 Comments

beginnings

[Pete’s] invented a product called an AIR Patch Cable designed to interface with an airplane’s intercom, and is looking to manufacture and assemble them himself — unfortunately, the circuit boards are tiny, and SMD components aren’t exactly the easiest to install. So he decided to build a pick and place machine to do it for him!

It’s not finished yet, but [Pete] has reached a major milestone — he’s finished the base CNC machine aspect of it. He opted for a kit build for the major mechanical components, the Shapeoko 2 — its a solid design and if you decided to make something from scratch it’d probably cost much more and take a lot longer.

From there he began selecting his electronics individually. He’s chosen the Big Easy Driver by Sparkfun to control his stepper motors, which supports a maximum size of NEMA 17 steppers, so he bought five of those too. To control it all, he’s using LinuxCNC which is an excellent choice — and if you’re not crazy about Linux, you can actually download Ubuntu 10.04 with LinuxCNC pre-installed for you to make it super easy — you’ll just need an old dedicated PC to use.

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Hackaday Links: March 23, 2014

March 23, 2014 by Mike Szczys 9 Comments

[Jack] sent us a link to a Metropolitan Museum of Art video showing off a mechanized desk that plays music and has a ton of hidden compartments. Furniture makers of yore built hidden compartments in furniture all the time. After all, there weren’t credit cards back in the day and you had to keep important documents, cash, and everything else on hand. What strikes us is that this mates woodworking of the highest caliber with precision mechanics.

Before you get rid of that old box spring, ask yourself if you need to store dimensional goods. If you rip off the outer fabric, the network of wire inside makes a reasonable lumber rack.

And since we’re talking trash, we enjoyed seeing this water bottle wire spool minder which [Daniel] sent our way.

You know those portable DVD players you can hang from a headrest to entertain the kids on long trips? Well [John’s] broke, and like chasing the dragon, once you’re hooked on watching videos during car trips there’s no going back. Luckily he was able to throw a Raspberry Pi at the problem. He now has a portable OpenElec XBMC device controlled via a smartphone.

[Jaromir] posted some breakout board footprints that you can use. It’s not the footprints that impress us, but the idea of using them to fill up board space when spinning a new PCB. [Thanks Sarah]

LEGO Gachapon. Need we say more? Okay, truth be told we had to look it up too; Wikipedia says it’s spelled Gashapon. These are coin-operated machines that dispense toys inside of plastic capsules. This one’s made of LEGO and it’s awesome.

[Mikhail] actually built his own ballast resistors for some HeNe laser tubes. This is a bit easier than it might sound at first, as they are much lower power than the tubes used in cutters. But none-the-less an interesting, and successful, experiment.