Hackaday Links: January 18, 2015

A little while ago, we complained that there aren’t many projects using the Microview, a very cool Arduino and OLED thing that might be just too big for a ring. [Johannes] answered the call with a slot car track timer. He’s using an infrared distance sensor to count off lap times for his slot car track and a mini thermal printer to print out the times. Video right here.

Too many cables in your freshman college dorm room? Here’s the solution.

Our Internet travels frequently take us to strange auctions (we’re still looking for a US Mail truck, btw), but this one takes the cake. 24kt gold plates that were flown in space for five and a half years weighing 6,015.5 grams (212.191 oz). At the current price of $1277.06/oz, this auction should go for $270,980 USD. I’m 99% sure this was part of the Long Duration Exposure Facility, but I have no clue why this much gold was flown. Surely they could have done the same amount of science with only a hundred thousand dollars worth of gold, right?

So here’s this, but this isn’t your everyday, “put an Arduino in a vibrator” crowdfunding campaign. No, they actually have some great tutorials. Did you know that a stroke sensor looks like shag carpeting? [Scott] tells us, “I believe the founders are all graduate students getting PhDs in something or other, starting a sex toy company on the side.” More power to ‘em.

Speaking of dildonics, the guy who coined that term will be giving one of the keynotes at the Vintage Computer Festival East this year. Yes, we’ll be there in full force.

Tracking Power Usage With A Raspi

With tiny, Internet-connected computers everywhere these days, home automation is finally hitting it big. [Jelora] was looking for a few more home automation projects and realized his electric meter had a pair of ‘digital information outputs’. With a Raspberry Pi and a few bits of wire, he figured out how to read this digital output and put a log of his electricity consumption up on the web.

The digital output on [Jelora]’s meter is a bit odd; it’s 1200 bps, 7 bits per character, parity, with one stop bit. It’s also a 50 kHz AC signal for a binary ‘0’ and nothing for a binary ‘1’. To read this signal, [Jelora] is using a diode to throw out half the signal, a 6N138 optoisolator so the Pi isn’t connected directly to the meter, and a small cap to smooth out the signal. Simple, and it works.

This cleaned up signal is then connected to serial to USB chip and a PHP script scrapes the data every minute. The data received from the meter is stored in a data base along with a few other bits of information: if the meter is being charged peak or off-peak rates, and the price per kWh. All this is saved on an IDE hard drive (more reliable than the SD card, surprisingly), and a ‘electricity cost per day’ is plotted on a nifty graph and served up by the Raspberry Pi.

Circuit Plotting With An HP Plotter

Over the last few years we’ve seen a few commercial products that aim to put an entire PCB fab line on a desktop. As audacious as that sounds, there were a few booths showing off just that at CES last week, with one getting a $50k check from some blog. [Connor] and [Feiran] decided to do the hacker version of a PCB printer: an old HP plotter converted to modern hardware with a web interface with a conductive ink pen.

The plotter in question is a 1983 HP HIPLOT DMP-29 that was, like all old HP gear, a masterpiece of science and engineering. These electronics were discarded (preserved may be a better word) and replaced with modern hardware. The old servo motors ran at about 1.5A each, and a standard H-Bridge chip and beefy lab power supply these motors were the only part of the original plotter that were reused. For accurate positioning, a few 10-turn pots were duct taped to the motor shafts and fed into the ATMega1284p used for controlling the whole thing.

One of the more interesting aspects of the build is the web interface. This is a small JavaScript app that is capable of drawing lines on the X and Y axes and sends the resulting coordinates from a server to the printer. It’s very cool, but not as cool as the [Connor] and [Feiran]’s end goal: using existing Gerber files to draw some traces. They’re successfully parsing Gerber files, throwing out all the superfluous commands (drills, etc), and plotting them in conductive ink.

The final iteration of hardware wasn’t exactly what [Connor] and [Feiran] had in mind, but that’s mostly an issue with the terrible conductivity of the conductive ink. They’ve tried to fix this by running the pen over each line five times, but that introduces some backlash. This is the final project for an electrical engineering class, so we’re going to say that’s alright.

Video below.

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Hackaday Retro Edition: Pen Computing

Although we’re well past the heyday of ‘pen computing’, and seemingly into a retro revival with laptops and tablets that come with Wacom styluses and digitizers, this doesn’t mean the pen computers of old weren’t useful. While they were mostly used for industrial applications, they were useful and some of the first practical applications of touch screen displays.

[Jason] got his hand on one of these ruggedized handheld PCs – specifically, an Itronix T5200. This three-pound mini notebook runs Windows CE Handheld PC Edition 3.01. The specs include a 74MHz RISC processor, 16 MB of RAM, 16MB of Flash, and a 7.3 inch monochrome touch screen with 640×240 resolution. It’s odd and old: when closed, it’s over two inches thick. You’ll be hard pressed to find a modern laptop that thick. [Jason]’s hardware is a pre-production version.

Unlike a lot of retro submissions that have somehow managed to pull up the Hackaday Retro Edition on old hardware, this machine actually has a browser. It’s old, it’s clunky, but it works. There are three options for getting this old computer up on the Internet – either IrDA, an RJ11 modem port, or RS232. [Jason] didn’t tell us which port he used to load up the retro edition, but he did send in a few pictures. You can check those out below.

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Twisted String Actuators

[Travis] tells us about a neat actuator concept that’s as old as dirt. It’s capable of lifting 7kg when powered by a pager motor, and the only real component is a piece of string.

The concept behind the twisted string actuator, as it’s known to academia, is as simple as putting a motor on one end of a piece of string, tying the other end off to a load, and putting a few twists in the string. It’s an amazingly simple concept that has been known and used for thousands of years: ballistas and bow-string fire starters use the same theory.

Although the concept of a twisted string actuator is intuitively known by anyone over the age of six, there aren’t many studies and even fewer projects that use this extremely high gear ratio, low power, and very cheap form of linear motion. A study from 2012 (PDF) put some empirical data behind this simple device. The takeaway from this study is that tension on the string doesn’t matter, and more strands or larger diameter strands means the actuator shrinks with a fewer number of turns. Fewer strands and smaller diameter strands take more turns to shrink to the same length.

As for useful applications of these twisted string actuators, there are a few projects that have used these systems in anthropomorphic hands and elbows. No surprise there, really; strings don’t take up much space, and they work just like muscles and tendons do in the human body.

Thanks [ar0cketman] for the link.

Make Awesome, Win Smoothieboard

If you haven’t looked around the RepRap project in a while, you probably haven’t heard about the Smoothieboard. It’s an extremely unique electronics board for 3D printers, laser cutters, and CNC machines that is trying to get away from Atmel and AVR microcontrollers and towards more powerful ARM micros. On the Smoothieboard, you’ll find enough five motor drivers, six big ‘ol MOSFETs for hot ends, fans, and beds, enough thermistor inputs for just about anything, and an Ethernet jack, because all 3D printers should be able to run headless.

The team behind the Smoothieboard has decided there’s not enough awesome included in the Smoothieboard already. To fix this, they’re opening up a contest where coders, documentarians, graphic artists, and creatives of all types can contribute to the Smoothieboard project. What’s the prize? A Smoothieboard, duh.

The Smoothieboard team is looking for a few good coders, builders, or anyone else to contribute to the Smoothieboard project. If you have an idea that would work with the Smoothieboard – a web interface like Octoprint running on the Smoothieboard, better documentation, graphics, or just want to build a five-axis CNC mill, this is where you sign up. The prize is a Smoothieboard 5XC, the top of the line board with five motor drivers.

Of course you’re always welcome to not contribute to open source projects, and for those consummate consumers, we have the Smoothieboard 5XC available in the Hackaday Store.

You have until February 15th to come up with a great project idea for a Smoothieboard. The best 30 project ideas will be chosen, and those projects will get a Smoothieboard. Actually building a project in a month isn’t a condition of the contest; the best idea wins.

New Part Day: Three-dimensional USB Connectors

There’s an old joke that says USB cables do not exist in three-dimensional Euclidian space. Try to plug a USB cable in a socket, and the first try will always be wrong. Flip it, try to plug it in, and that will also be wrong. You will only succeed on the third try, and this is proof that USB connectors exist in higher planes of reality with arcane geometries. The joke is as old as the Pythagoreans, who venerated USB connectors as gods.

The waveform has collapsed, the gods profaned, and USB connectors that exist in only three dimensions have arrived. We’re talking, of course, about reversible USB Type A connector that will plug in the first time, every time. No need for electromancy or the “looking on the cable for the USB logo and plugging it in with that side up” method used by tech plebeians.

This discovery came after going through my daily roundup of crowdfunding press releases, eventually landing me on this idiotic project. It’s a USB charge cable that’s supposed to charge your phone twice as fast, despite the fact that charging speed is a function of current, and that’s determined by whatever you’re charging from, not the cable. Terrible idea, but they do have something interesting: a three-dimensional USB connector.

connUSBThe connector isn’t the brand new USB 3.1 Type C connector that will eventually find its way into phones, laptops, wearables of all types. This is your standard Type A USB plug you’ve known and loved for the past eighteen years. The difference here is that the chunky block of plastic that has made the common USB cable non-reversible for so many years is gone. In its place is a tiny strip of plastic that has contacts on both sides. Yes, it took nearly two decades for someone to figure out this would be a marketable idea.

While searching for a source for these three-dimensional USB connectors, the only source I could come up with was Wurth Elektronik, With Farnell/Element14 carrying a selection of connectors, a few available on Digikey, and some available on Mouser. There are even a few pre-made reversible cables available, with Tripp Lite leading the game right now.

For integrating one of these connectors into your build, there’s only one thing to watch out for: the pinout for these plugs is mirrored on each side of the thin strip of plastic going down the middle of the connector. This means your VCC and GND pins will be right next to each other, your D+ and D- signal pins right next to each other, and now you have to do your layout with eight pins instead of only four.

While it may not be groundbreaking and it makes for some confusing PCB layout work, but as told by a highly successful crowdfunding campaign, this can be a real feature for a product.

If you’ve recently come across a component, connector, or part that’s unique, interesting, or downright cool everyone should know about, send it on in and we’ll take a look at it.