Worn Train Rails Get Judged By Laser

July 8, 2018 by Donald Papp 32 Comments

[Calango] is a railway technician, and for a school final project created the Rail Wear Surveillance Trolley (RWST) which is a delightfully designed device made mainly from PVC conduit with one job: travel down a segment of train track while shining a green laser onto the rail, and capture camera images. The trolley holds both the laser and the camera at just the right angles for the camera to capture a profile of the rail’s curved surface. The images are sent via Bluetooth to a smartphone for later analysis. Rail wear can be judged by checking how well the profile of the rail conforms to the ideal profile of an unworn segment. The trolley is manually pushed by an operator, but [Calango] says that ideally, it would be self-propelled and able to inspect a length of the track then return on its own.

The project was made on a tight budget, which led to some clever solutions like using a rotary encoder attached to a wheel as a makeshift distance sensor. If things get desperate enough, it’s even possible to roll your own rotary encoder with a 3D printer and two microswitches.

Automatic Sunglasses, No Battery!

July 8, 2018 by Jenny List 26 Comments

There are some projects that are so simple they require very little description, and [Bobricius’s] automatic sunglasses definitely fit into that category. Their story starts with the fad for 3D displays a few years ago, a resurfacing of the movie business’s periodic flirtation with the third dimension in the hope of using the gimmick to bring in more moviegoers. There was a time when you could hardly encounter a new TV or graphics card without it coming with a pair of cheap plastic glasses with LCD panels instead of lenses that would alternately shutter the view for each eye to create the 3D illusion.

Of course, once everyone had seen the film with the blue aliens and tried a few other titles on their new toy, they grew tired of headaches, nausea, and half-brightness. The glasses gathered dust, and the fancy 3D telly never ventured beyond two dimensions again. Except for [Bobricius’s] glasses, that is, for he’s levered out the 3D driver electronics and replaced them with a tiny SOIC-8 solar cell. Light hits the cell, the LCD gets a charge and darkens, no light and they remain transparent. Similar to welding goggles — though they usually use a battery. It’s unclear whether they can get a little too dark on a really bright day and whether they are something akin to [Zaphod Beeblebrox]’s peril-sensitive sunglasses, but we really applaud the idea. They are so simple that this Hackaday write-up is probably longer than their write-up, but they remain a neatly executed idea and we like that.

You can, of course, use a battery, or achieve the same effect by more complex means. But if the [Beeblebrox] glasses are closer to your requirements, we’ve got that covered too.

RGB Sensor’s New Job: Cryptocurrency Trade Advisor

July 8, 2018 by Donald Papp 15 Comments

[XenonJohn] dabbles in cryptocurrency trading, and when he saw an opportunity to buy an RGB color sensor, his immediate thought — which he admitted to us would probably not be the immediate thought of most normal people — was that he could point it to his laptop screen and have it analyze the ratio of green (buy) orders to red (sell) orders being made for crypto trading. In theory, if at a given moment there are more people looking to buy than there are people looking to sell, the value of a commodity could be expected to go up slightly in the short-term. The reverse is true if a lot of sell orders coming in relative to buy orders. Having this information and possibly acting on it could be useful, but then again it might not. Either way, as far as out-of-left-field project ideas go, promoting an RGB color sensor to Cryptocurrency Trading Advisor is a pretty good one.

Since the RGB sensor only sees what is directly in front of it, [XenonJohn] assembled a sort of simple light guide. By enclosing the area of the screen that contains orders in foil-lined cardboard, the sensor can get a general approximation of the amount of red (sell orders) versus green (buy orders). The data gets read by an Arduino which does a simple analysis and sends alerts when a threshold is crossed. He dubbed it the Crypto-Eye, and a video demo is embedded below.

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Tiny Websites Have No Server

July 7, 2018 by Al Williams 50 Comments

A big trend in web services right now is the so-called serverless computing, such as Amazon’s Lambda service. The idea is you don’t have a dedicated server waiting for requests for a specific purpose. Instead, you have one server (such as Amazon’s) listening for lots of requests and on demand, you spin up an environment to process that request. Conceptually, it lets you run a bit of Javascript or some other language “in the cloud” with no dedicated server. https://itty.bitty.site takes this one step farther. The site creates self-contained websites where the content is encoded in the URL itself.

Probably the best example is to simply go to the site and click on “About itty bitty.” That page is itself encoded in its own URL. If you then click on the App link, you’ll see a calculator, showing that this isn’t just for snippets of text. While this does depend on the itty.bitty.site web host to provide the decoding framework, the decoding is done totally in your browser and the code is open source. What that means is you could host it on your own server, if you wanted to.

At first, this seems like a novelty until you start thinking about it. A small computer with an Internet connection could easily formulate these URLs to create web pages. A bigger computer could even host the itty.bitty server. Then there’s the privacy issue. At first, we were thinking that a page like this would be hard to censor since there is no centralized server with the content. But you still need the decoding framework. However, that wouldn’t stop a sophisticated user from “redirecting” to another — maybe private — decoding website and reading the page regardless of anyone’s disapproval of the content.

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Multi-Board Solder Stencils Explained

July 7, 2018 by Jenny List 13 Comments

There was a time when reflow soldering was an impossibly exotic process at our level, something that only the most superhuman of hackers could even dream of attempting. But a demystification of the process plus the ready availability of affordable PCB and stencil manufacture has rendered into the range of almost all constructors, and it is likely that many of you reading this will have done it yourself.

Screen-printing solder paste onto a single board presents a mild alignment challenge, but how about doing it with many boards at once? [Eric Gunnerson] had this problem with a small-volume board he’s selling, and not being in the happy position of having his PCBs supplied on a panel, had to create his own multi-board alignment jig and stencil. His write-up provides a comprehensive and fascinating introduction to the process whether you are an occasional dabbler or embarking on a production run as he is.

The problem facing any would-be stenciler is that the board has to be held in place reliably in the same alignment as the stencil. With a single board, it’s easy enough to do the usual thing of taping scraps of PCB board to constrain its edges and hold it in place as a rudimentary jig, then lower the stencil onto it. Perhaps you’ve used one of those commercial stencil jigs, in which a set of magnets hold the stencil in place, or maybe you use pins to line everything up.

[Eric] takes us through the process of creating a laser-cut alignment jig for twelve boards, and cutting a matching twelve-board stencil. This includes all the software side using Inkscape, the selection of materials to match PCB thickness, and some of the issues with cutting Mylar sheet for the stencil without shrinkage at the corners. He’s using pins for alignment, and he even finds a handy supply of those in the form of shelf support pins.

We’ve visited the world of reflowing many times before. If you’d like a primer, here’s our Tools of the Trade piece on it, and if you aren’t daunted by larger projects, here’s an account of a prototype run of a significantly complex board.

A Peek Into A Weed-Eating Robot’s Test Fixtures

July 7, 2018 by Donald Papp 2 Comments

When it comes to production, fast is good! But right the first time is better. Anything that helps prevent rework down the line is worth investing in. Some of the best tools to catch problems are good test fixtures. The folks at Tertill (a solar-powered robot for killing weeds that kickstarted last year) took the time to share two brief videos of DIY test fixtures they use to test components before assembly.

The videos are short, but they demonstrate all the things that make a good test: on the motor tester there are no connectors or wires to fiddle with, the test starts automatically, and there is clear feedback via prominent LEDs. The UI board tester also starts automatically and has unambiguous LED feedback, and sports a custom board holder with a recess just the right shape for the PCB. Once the board is in, the sled is pushed like a drawer to make contact with the test hardware and begin the test. The perfectly formed recesses in both units serve another function as well; they act as a go/no-go test for the physical shape of the components and contacts being tested.

Both videos are embedded below; and while there isn’t much detail on the actual test hardware, we do spy a Raspberry Pi and at least two Adafruit logos among other hacker-familiar elements like laser-cut acrylic, 3D printed plastic, pogo pins, and a PVC junction box.

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This Smart Pill Uses A Stomach Acid Battery

July 7, 2018 by Steven Dufresne 34 Comments

[Curt White] is working on a smart pill whose copper-zinc battery will use his own stomach acid as the electrolyte. It’s not that unusual of an idea, MIT tested a similar approach in a pig. It’s also better than using lithium ion batteries, something we covered in this PSA.

His starting point is a small, hacked activity tracker with its Nordic nRF51822 ARM Cortex-M0 and Bluetooth LE SoC. Most everything else is removed. The battery electrodes are sewn onto a plastic mesh cut to the activity tracker’s dimensions. Three coin type super capacitors and a boost converter sit between the battery and the SoC.

He uses the Bluetooth LE for communication, sort of. BLE devices constantly transmit information about themselves and it’s this which you see when scanning for available devices. Included in that transmission is a UUID (Universally Unique Identifier) and a name (e.g. “smartpillxyz”). He has the pill transmit data by putting it in that name. This saves power by minimizing the time which the pill’s Bluetooth radio is turned on. The smartphone app extracts the data from these transmissions without ever connecting.

His goal is to monitor the voltage and the maximum current. This will tell him if his stomach acid battery works and what can be powered by it. First tests will use regurgitated gastric fluid and then later he’ll swallow the pill himself. As he puts it, why not, “people swallow and pass all kinds of weird stuff without a problem.” Thay may sound cavalier but judging by his hackaday.io page, he’s doing his homework.