Hackaday Links: April 15th, 2018

April 15, 2018 by Brian Benchoff 42 Comments

San Fransisco is awash in electric scooters. Three companies — Lime, Bird, and Spin — have been dumping ‘smart’ electric scooters on the sidewalks of San Fransisco over the last few weeks. The business plan for all these companies is to allow anyone to ride them via an app. $1 unlocks the scooter, and rides are fifteen cents a minute. No one, it appears, is looking at the upside of abandoned, dead electric scooters: they’re a remarkable source of lithium batteries and brushless motors. Hello, my name is Mr. Cyberpunk. My friends and I drive around the city collecting abandoned electric scooters to harvest their batteries and motors. A quick hit from a drill in the middle of the top panel of a Bird scooter disables the cellular modem, but then you don’t get to harvest the Particle dev board. You’re welcome, Mr. Doctorow, for the scene in your next novel.

There are a huge number of tips and tricks that are obvious if you already know them, and genius if you don’t. Working with wood? Need to hide a gap? Use sawdust and wood glue to make DIY wood filler. The trick here is using sawdust from whatever you’re trying to hide a gap in, but it’s not a bad idea to keep a few small containers of different sawdusts if you’re working with exotic tropical hardwoods. Titebond III, mango.

Ever since the Bayeux tapestry meme generator of 2003, embroidery has been recognized as a legitimate art form. [Irene Posch] is using traditional embroidery skills to create a computer. Conductive thread exists, but you can’t make a computer out of just wire; you need some sort of switching element. This is a relay computer, with the relays built out of beads, coils of conductive thread, and a tiny flippy bit. This is the best picture you’re going to get of the relay. This is still a work in progress and the density of components means this will probably never meet any reasonable definition of ‘computer’, but it is digital logic, done completely with tools in the embroidery toolset.

You know what’s awesome? Hashtag Badgelife. What is Badgelife? It’s the hardware demoscene of independent electronic conference badges, mostly going down at DEF CON every year. This year, Badgelife is bigger than ever. Want proof? AND!XOR, the folks behind the infamous Bender badge and last year’s Hunter S. Rodriguez badge have unleashed this year’s design. It was a Kickstarter, until it sold out. The DC Furs have launched their pre-order whatever for a badge filled with LEDs and fleas. Most surprisingly, there will now be an official mini-village of Badgelife at this year’s Defcon! This is a hardware demoscene, people, and if you want to be as cool as the guys rocking Amiga homebrew in 1993, you gotta get on board with the badgelife.

Rotary Encoders Become I2C Devices

April 15, 2018 by Brian Benchoff 42 Comments

Rotary encoders are the bee’s knees. Not only do you get absolute positioning, you can also use a rotary encoder (with a fancy tact button underneath) for an easy UI for any electronics project. There’s a problem with rotary encoders, though: it’s going to use Gray code or something weird, and getting a rotary encoder to work with your code isn’t as easy as a simple button.

For his Hackaday Prize project, [fattore.saimon] has come up with the solution for using multiple rotary encoders in any project. It’s a board that turns a rotary encoder into an I2C device. Now, instead of counting rising and falling edges, adding a rotary encoder to a project is as easy as connecting four wires.

The project is built around the PIC16F18344, a small but surprisingly capable microcontroller that reads a rotary encoder and spits data out as an I2C slave device. Also on board are a few pins for an RGB LED, general purpose pins, the ability to set all seven bits of the I2C address (who wants 127 rotary encoders?), and castellated holes for connecting several boards together.

This project is an update of [fattore]’s earlier I2C Encoder, and there are a lot of improvements in the current version. It’s slightly smaller, has better connectors, and uses a more powerful microcontroller. That’s just what you need if you want a ton of rotary encoders for all those cool interactive projects.

Fail Of The Week: Casting A Bolt In A 3D-Printed Mold

April 15, 2018 by Mike Szczys 25 Comments

Here’s a weird topic as a Fail of the Week. [Pete Prodoehl] set out to make a bolt the wrong way just to see if he could. Good for you [Pete]! This is a great way to learn non-obvious lessons and a wonderful conversation starter which is why we’re featuring it here.

The project starts off great with a model of the bolt being drawn up in OpenSCAD. That’s used to create a void in a block which then becomes two parts with pegs that index the two halves perfectly. Now it’s time to do the casting process and this is where it goes off the rail. [Pete] didn’t have any flexible filament on hand, nor did he have proper mold release compound. Considering those limitations, he still did pretty well, arriving at the plaster bold seen above after a nice coat of red spray paint.

He lost part of the threads getting the two molds apart, and then needed to sacrifice one half of the mold to extract the thoroughly stuck casting. We’ve seen quite a bit of 3D printed molds here, but they are usually not directly printed. For instance, here’s a beautiful mold for casting metal but it was made using traditional silicon to create molds of the 3D printed prototype.

Thinking back on it, directly 3D printed molds are often sacrificial. This method of pewter casting is a great example. It turns out gorgeous and detailed parts from resin molds that can stand up to the heat but must be destroyed to remove the parts.

So we put it to you: Has anyone out there perfected a method of reusable 3D printed molds? What printing process and materials do you use? How about release agents — we have a guide on resin casting the extols the virtues of release agent but doesn’t have any DIY alternatives. What has worked as a release agent for you? Let us know in the comments below.

Hackaday & Tindie UK Tour Adds Milton Keynes

April 15, 2018 by Jenny List 4 Comments

Hackaday and Tindie are on the road in the UK and we want you to grab one of your projects and come hang out! We have three meetups scheduled over the coming week:

Fresh from our Dublin Unconference and following our London meetup which is happening today, Hackaday and Tindie are staying on the road. We’ve already told you about Nottingham on the 18th, and Cambridge on the 19th, to those two we’re adding Milton Keynes on the 23rd.

We’ll be at convening at Milton Keynes Makerspace on the evening of Monday the 23rd, a community hackspace venue with easy access and parking, and a vibrant community of members. It shares an industrial unit with the local Men In Sheds, so look out for their sign. Entry is free but please get a ticket so we know the amount of pizza and soft drinks we need to arrange. Bring along whatever you are working on, we’d love to see one of your projects, whatever it is!

At the end of the month we will also be at Maker Faire UK in Newcastle, Meeting you, our readers, is important to us, and though we can’t reach everywhere we would like to try to get further afield in the future. Please watch this space.

One-Pixel Attack Fools Neural Networks

April 15, 2018 by Elliot Williams 34 Comments

Deep Neural Networks can be pretty good at identifying images — almost as good as they are at attracting Silicon Valley venture capital. But they can also be fairly brittle, and a slew of research projects over the last few years have been working on making the networks’ image classification less likely to be deliberately fooled.

One particular line of attack involves adding particularly-crafted noise to an image that flips some bits in the deep dark heart of the network, and makes it see something else where no human would notice the difference. We got tipped with a YouTube video of a one-pixel attack, embedded below, where changing a single pixel in the image would fool the network. Take that robot overlords!

Or not so fast. Reading the fine-print in the cited paper paints a significantly less gloomy picture for Deep Neural Nets. First, the images in question were 32 pixels by 32 pixels to begin with, so each pixel matters, especially after it’s run through a convolution step with a few-pixel window. The networks they attacked weren’t the sharpest tools in the shed either, with somewhere around a 68% classification success rate. What this means is that the network was unsure to begin with for many of the test images — making it flip from its marginally best (correct) first choice to a second choice shouldn’t be all that hard.

This isn’t to say that this line of research, adversarial training of the networks, is bogus. The idea that making neural nets robust to small changes is important. You don’t want turtles to be misclassified as guns, for instance, or Hackaday’s own Steven Dufresne misclassified as a tobacconist. And you certainly don’t want speech recognition software to be fooled by carefully crafted background noise. But if a claim of “astonishing results” on YouTube seems too good to be true, well, maybe it is.

Thanks [kamathin] for the tip!

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Shutter Bug Goes Extreme With Scratch-Built Film Camera

April 15, 2018 by Dan Maloney 5 Comments

Should a camera build start with a sand mold and molten aluminum? That’s the route [CroppedCamera] took with this thoroughly impressive camera project.

When we think of cameras these days, chances are we picture the ones that live inside the phones in our pockets. They’re the go-to image capture devices for most of us, but even for the more photographically advanced among us, when a more capable camera is called for, it’s usually an off-the-shelf DSLR from Canon, Nikon, or the like. Where do hand-built cameras fall in today’s photography world? They’re a great way to add a film option to your camera collection.

Cast lens body before machining

[CroppedCamera] previously built a completely custom large-format view camera, but for this build he decided that something a bit more portable might do. The body of the camera is scratch-built from aluminum, acting as the lightproof box to hold the roll film and mount the leaf-shutter lens. There’s an impressive amount of metalwork here — sand casting, bending, TIG welding, and machining all came into play, and most of them new skills to [CroppedCamera]. We were especially impressed with the shrink-fit of the lens cone to the body. It’s unconventional looking for sure, but not without its charm, and it’s sure to make a statement dangling around his neck.

It’s tough to find non-digital DIY camera builds around here — best we could do were these laser-cut plywood modular cameras. Then again, you can’t beat this wearable camera for functional style.

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Hide Secret Messages In Plain Sight With Zero-Width Characters

April 15, 2018 by Ben James 30 Comments

Fingerprinting text is really very nifty; the ability to encode hidden data within a string of characters opens up a large number of opportunities. For example, someone within your team is leaking confidential information but you don’t know who. Simply send each team member some classified text with their name encoded in it. Wait for it to be leaked, then extract the name from the text — the classic canary trap.

Here’s a method that hides data in text using zero-width characters. Unlike various other ways of text fingerprinting, zero width characters are not removed if the formatting is stripped, making them nearly impossible to get rid of without re-typing the text or using a special tool. In fact you’ll have a hard time detecting them at all – even terminals and code editors won’t display them.

To make the process easy to perform, [Vedhavyas] created a command line utility to embed and extract a payload using any text. Each letter in the secret message is converted to binary, then encoded in zero-width characters. A zero-width-non-joiner character is used for 0, and a zero-width-space character for 1.

[Vedhavyas’] tool was inspired by a post by [Tom], who uses a javascript example (with online demo) to explain what’s going on. This lets you test out the claim that you can paste the text without losing the hidden data. Try pasting it into a text editor. We were able to copy it again from there and retrieve the data, but it didn’t survive being saved and cat’d to the command line.

Of course, to get your encoding game really tight, you should be looking at getting yourself an enigma wristwatch…

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