Category Archives: hackaday.io

The World’s Lightest Brushless FPV Quadcopter

When a claim is made for something being the world’s lightest it is easy to scoff, after all that’s a bold assertion to make. It hasn’t stopped [fishpepper] though, who claims to have made the world’s lightest brushless FPV quadcopter. Weighing in at 32.4 grams (1.143 oz) it’s certainly pretty light.

The frame is a circular design cut from carbon-fiber-reinforced polymer, and on it are mounted four tiny brushless motors. In the center are the camera and battery on a 3D printed mount, as well as custom flight and speed controller boards. There are a series of posts detailing some of the design steps, and the result is certainly a capable aircraft for something so tiny. If you fancy experimenting with the design yourself, the files are available for download on the first page linked above.

There are two aspects to this build that make it interesting to us. First, the lightest in the world claim. We think someone will come along with something a bit lighter, and we can’t wait to see a lightest multirotor arms race. Good things come of technology races, which brings us to the second aspect. Governments are busy restricting the use of larger multirotors, to the extent that in some parts of the world all that will be available for non professionals will be sub-200g toy craft. Any project like this one which aims to push the boundaries of what is possible with smaller multirotors is thus extremely interesting, and we hope the community continue to innovate in this direction if only to make a mockery of any restrictions.

To get some idea of the sort of legislative measures we might be seeing, take a look at our coverage of a consultation in just one country.

Hands On With The First Open Source Microcontroller

2016 was a great year for Open Hardware. The Open Source Hardware Association released their certification program, and late in the year, a few silicon wizards met in Mountain View to show off the latest happenings in the RISC-V instruction set architecture.

The RISC-V ISA is completely unlike any other computer architecture. Nearly every other chip you’ll find out there, from the 8051s in embedded controllers, 6502s found in millions of toys, to AVR, PIC, and whatever Intel is working on are closed-source designs. You cannot study these chips, you cannot manufacture these chips, and if you want to use one of these chips, your list of suppliers is dependent on who has a licensing agreement with who.

We’ve seen a lot of RISC-V stuff in recent months, from OnChip’s Open-V, and now the HiFive 1 from SiFive. The folks at SiFive offered to give me a look at the HiFive 1, so here it is, the first hands-on with the first Open Hardware microcontroller.

hifive1hero

Before I dig into this, I must discuss the openness of the HiFive 1, and RISC-V in general. Free Software and Open Hardware is a religion, and it’s significantly more difficult to produce Open Hardware than Free Software. No matter how good or how Open the design is, the production of the first Open Source microcontroller will generate far too many comments from people who use the words ‘moral imperative’ while citing utilitarian examples of why Open and Libre is good. You should ignore these comments, but not just because these people have only read the back cover of the Cliff’s Notes for Philosophy For Dummies.

The Openness of the HiFive 1 and RISC-V

The biggest selling point for RISC-V chips is that there are no licensing fees, and this microcontroller is Open Source. This is huge — your AVRs, PICs, ARMs, and every other microcontroller on the planet is closed hardware. You can’t study the silicon. If we’re ever going to get a completely Open Source computer, it has to start somewhere, and here it is.

With that said, this is an Arduino-compatible board with an FTDI chip providing the USB to serial conversion. If we had a facepalm emoji, we’d use it here. An FTDI chip is not Open Source, and they have designed drivers to break chips that aren’t theirs. The design files for the HiFive 1 were made with Altium, a proprietary and non-Free software.

This was the best picture for this section of content.This was the best picture for this section of content.

Will Stallman ever say the HiFive 1 is Free as in speech? Absolutely not. Instead, the HiFive 1 is an incrementally more Free microcontroller compared to a PIC, ARM, or AVR. There will be people who will argue – over the Internet, using late-model Intel processors with Management Engines — this is insufficient to be called Free and Open Source. To them, I will simply link to the Nirvana fallacy and ask them to point me to a microcontroller that is more Free and Open Source. Let’s not cut down the idea of an Open Source microcontroller because it’s not perfect on the first release.

Hardware Teardown

So, what’s in the HiFive 1? The spec sheet is simple enough, the datasheet is complete enough,  although there are some caveats:

  • Microcontroller: SiFive Freedom E310 (FE310)
    • CPU: SiFive E31 CPU
    • Architecture: 32-bit RV32IMAC
    • Speed: 320+ MHz (the stock frequency seems to be about 256 MHz, this can be changed)
    • Performance: 1.61 DMIPs/MHz
    • Memory: 16 KB Instruction Cache, 16 KB Data Scratchpad
    • Other Features: Hardware Multiply/Divide, Debug Module, Flexible Clock Generation with on-chip oscillators and PLLs
  • Operating Voltage: 3.3 V and 1.8 V
  • Input Voltage: 5 V USB or 7-12 VDC Jack
  • IO Voltages: Both 3.3 V or 5 V supported
  • Digital I/O Pins: 19
  • PWM Pins: 9
  • SPI Controllers/HW CS Pins: 1/3
  • External Interrupt Pins: 19
  • External Wakeup Pins: 1
  • Flash Memory: 128 Mbit Off-Chip (ISSI SPI Flash)
  • Host Interface (microUSB): Program, Debug, and Serial Communication

Basically, the HiFive 1 is the SiFive FE310 microcontroller packaged in an Arduino Uno form factor. The pin spacing is just as stupid as it’s always been, and there is support for a few Adafruit shields sitting around in the SDK.

There are no analog pins, but there are two more PWM pins compared to the standard Arduino chip. The Arduino Uno and Leonardo have 32 kilobytes of Flash, while the HiFive 1 has sixteen Megabytes of Flash on an external SOIC chip.

The HiFive 1 supports 3.3 and 5V I/O, thanks to three voltage level translators. The support for 5V logic is huge in my opinion — nearly every dev board manufacturer has already written off 5V I/O as a victim of technological progress. The HiFive doesn’t, even though the FE310 microcontroller is itself only 3.3V tolerant. It should be noted the addition of the voltage level translators add at least a dollar or two to the BOM, and double that to the final cost of the board. It’s a nice touch, but there’s room for cost cutting here.

Other than that, the only other chip of note on the board is the FTDI FT2232HL, a well-supported but most certainly not Free and Open Source USB to UART chip. This is a two-port chip that provides programming, serial, and debug connections simultaneously.

Getting Started With The HiFive 1

blinking-gifThe folks at SiFive realize documentation and SDKs are necessary to turn a chip into a development board. To that end, they have a bare-metal SDK and support for the Arduino IDE. The board itself comes with a bootloader, and when you plug the HiFive 1 into a USB you get the equivalent of the Blink sketch from the Arduino. Yes, you too can have Open Source blinkies. What a magical time to be alive.

Right now there are two methods of programming the HiFive 1. The Freedom E SDK, and the Arduino IDE. The Arduino IDE appears to be dependent on the Freedom E SDK, so either way, you’ll have to get the SDK running.

Right now, the SDK only works under Linux (and OS X, and possibly Cygwin), but support for Windows is coming. For Linux users, the getting started guide is more than sufficient, although it will take quite a while (at least 30 minutes) to build all the tools.

Once the Freedom E SDK is installed, support for the Arduino IDE pretty much falls into place. You’ll have to futz around with the Boards Manager, but with a few clicks, you get something fantastic. You can blink an LED with Open Source Hardware.

moreanimatedgifs

 Actually Programming the Thing

Blinking an LED is proof enough this can be programmed, but what about the vast SDK we had to install before getting the Arduino IDE working? Here, too, it’s pretty easy to get the SDK up and running:

For this example, I simply changed the ‘hello world’ program shipped with the SDK to a ‘hello Hackaday’ program, compiled it, and ran it. Yes, someone as dumb as me can compile and upload a program to the HiFive 1.

This Stuff is Still New, Okay?

Before receiving the HiFive 1, I originally planned to benchmark this dev board against other small, common dev boards. The SDK comes with a Dhrystone program, making this the obvious choice. The results were not good, but this isn’t a reflection of the power of the FE310 microcontroller. Allow me to present the shocking infographic you should not pay attention to:

Ignore this infographic

This test used this Dhrystone Arduino sketch with the Arduino Micro, HiFive 1, and the Teensy 3.6. As you would expect the Arduino Micro performed poorly (but still ten times faster than a mainframe from 1988), and the Teensy 3.6 was extremely fast. According to this benchmark, the HiFive 1 did terribly at barely twice the computing power of the Arduino while running 16 times faster. If this benchmark was accurate, it would immediately spell the end of the RISC-V ISA.

The above benchmark is not accurate, and the poor Dhrystone performance was due to incorrect assumptions about the timer’s frequency. I plopped this problem up on the SiFive forums, and a patch was available in a few hours. What does the real benchmark say?

dhrystone3That’s a fast microcontroller. RISC architecture is gonna change everything.

love this test. Beginning this review, I originally planned to run a few benchmarks on an Arduino, a Teensy, and the HiFive 1, throw together a graph and spend a hundred or so words on the results.  I got so much more.

Right off the bat, we can see the HiFive 1 is fastReally, really fast. Right now, if you want to build a huge RGB LED display, you have one good option: the Teensy 3.6. If you need a microcontroller to pump a lot of data out, the Teensy has the power, the memory, and the libraries to do it easily. In this small but very demanding use case, the HiFive 1 might be better. The HiFive 1 has more Flash (although it’s an SPI Flash), it has DMA, and it has roughly twice the processing power as the Teensy 3.6. This could be very, very cool, and I can’t wait to see the real life examples of how much the HiFive 1 can push out of its pins.

There’s your hundred word review on the performance of the HiFive 1 based on synthetic benchmarks. However, getting this benchmark working revealed far more about the state of the HiFive’s software, and how much support SiFive is throwing at it.

Admittedly, I do have a very early version of this board, and the CrowdSupply campaign for the HiFive 1 was only funded last week. No one would expect one of the three demo apps shipped with a newly released board with a mature architecture to be completely broken (unless it’s an Allwinner chip, but whatever). Very few people would expect the devs to get a patch out in less than 24 hours in response to a random person on a support forum.

All of this circles back to a single observation on the HiFive 1: It’s new. The HiFive 1 and all RISC-V microcontrollers don’t have a vast market share, user base, or decades of work behind them. However, the SiFive team seems to be taking their work seriously. They’re fixing the problems they have, and they’re constantly pushing out new documentation. This is great, and a very good indication of how much support the RISC-V chips from SiFive will have.

Chips As A Service

I should note that the folks at SiFive aren’t in the business of building RISC-V Arduino boards. They’re in the business of making chips for people. This is custom silicon we’re talking about here.

The easiest parallel to draw is between SiFive and OSH Park. These companies don’t have their own manufacturing capability; the value is in connecting end users (engineers, startups) to manufacturers. OSH Park connects you to a board house that really knows purple, and SiFive connects you to a chip fab. In the case of the FE310, that’s TSMC.

For anyone who wants silicon you can study, this is great. No, it’s not as simple as sending a board off to a fab house, but it’s a start. The fact that SiFive chose to start with Open Hardware is great, and we can’t wait to see the other hardware made with their sweat and hydrofluoric acid.

It’s a Beginning

At the base level, the HiFive 1 is a powerful microcontroller with a lot of Flash, with support for hundreds of Arduino libraries. That’s great, and alone this might be worth the $60 price of admission.

However, the big story here is the Openness of the HiFive 1. Is it completely open? No. the HiFive 1 itself uses an FTDI chip, and I’ve heard rumor and hearsay the FE310 chip has proprietary bits that are ultimately inconsequential to the function of the chip. A strict interpretation of Open Hardware will not allow this board to be called Open Hardware. Those who advance this interpretation are dumb, and to counter this argument I will quote the man himself:

…We need to distinguish levels in the design of a digital product (and maybe some other kinds of products). The circuit that connects the chips is one level; each chip’s design is another level. In an FPGA, the interconnection of primitive cells is one level, while the primitive cells themselves are another level. In the ideal future we will want the design to be free at all levels. Under present circumstances, just making one level free is a significant advance.

– Richard M. Stallman, Free Hardware And Free Hardware Designs

A design that fails to be completely Open does not deserve to be grouped with designs that are explicitly closed.

Nevertheless, this is the best we have so far, and it is only the beginning. We’re going to have more microcontrollers that are more Open, but until then, the HiFive 1 is actually a pretty cool board.

Python Solution To A Snake Cube Puzzle

Puzzles provide many hours of applied fun beyond any perfunctory tasks that occupy our days. When your son or daughter receives a snake cube puzzle as a Christmas gift — and it turns out to be deceptively complex — you can sit there for hours to try to figure out a solution, or use the power of Python to sort out the serpentine conundrum and use brute-force to solve it.

Finding himself in such a scenario, [Randy Nuss] walks us through his solution while giving insight into how he approaches writing code — learning other methods of problem solving can be a valuable experience in itself, and thematically fitting, considering this particular case! [Nuss] includes his final code near the end of his post, but his write up instead outlines it in enough detail that would guide others along the correct path. Once it ran successfully, he was cajoled into creating a visualization of the solution since the actual code completes in less than a second.

If a hack is a means to make a given task easier to accomplish, then some fancy coding to solve a puzzle — while perhaps defeating the purpose — is arguably still a hack that simply uses a different avenue. Sometimes, the puzzle winds up being the hack itself when you are gifting something special.

[Thanks for the tip, Josh!]

Visualization of a Phased Array Antenna System

Phased array antenna systems are at the cusp of ubiquity. We now see Multiple-Input Multiple-Output (MIMO) antenna systems on WiFi routers. Soon phased array weather radar systems will help to predict the weather and keep air travel safe, and phased array base stations will be the backbone of 5G which is the next generation of wireless data communication.  But what is a phased array antenna system?  How do they work?  With the help of 1024 LEDs we’ll show you.

It’s good to first review what phased array antenna technology has been used for in the past, where it is today, and where it is going, then we will show you how it all works.

The Military Industrial Complex: Pioneers in Phased Array Technology

FPS85, one of the first full-scale phased array radar implementations.Phased array technology was pioneered for military applications. The ever increasing speed of aircraft and ordnance after the second world war pushed the requirement for antenna sweep time from seconds to milliseconds.

The first full-scale phased array radar systems was the FPS-85, which is used for detecting and tracking space objects which by their very nature are fast moving.

Additional iconic examples of phased array radar technology include the SPY-1 phased array radar, PAV PAWS, and others.

The First Widespread Use of Phased Array Radar Technology for a Civilian Application:

To manage increases in air traffic and to consolidate numerous existing aging radar infrastructure, including most types of primary air traffic control radar and weather radar, the multi-function phased array radar (MPAR) system is under development and prototypes to be fielded soon. This will become one of the first (likely the very first) wide scale civilian deployment of phased array radar technology.

More Wireless Bandwidth for Your Mobile Devices

Key to the 5th generation of wireless systems (5G) is the use of phased array antenna technology, where individual wireless devices will be tracked by beams transmitted/received from the base station thereby enabling greater data bandwidths which are discretized into individual microwave beams.

0408

Many WiFi routers now use Multiple Input Multiple Output (MIMO) antenna arrays for the purpose of reducing multi-path signal loss, which is quickly becoming more and more of a problem as data rates increase.

asus-rt-ac5300_678x452

How Do Phased Array Antenna Systems Work?

How do you create a ‘beam of microwave energy’ and direct your receiver onto just the right point in space?

ps-enpSynthesizing a focused beam of microwave radiation with an array of elements fed with the same microwave signal where each element is independently phase controlled.

An excellent tutorial is presented here, but the key take away is that if we feed an array of antenna elements with the same microwave signal then we can use these elements to direct (or steer as it is commonly referred to) a microwave beam anywhere in space.  This beam steering is achieved by the use of a phase shifter (or its equivalent) in series with each and every antenna element.

To make the above explanation more interesting and understandable, friends of mine at MIT Lincoln Laboratory created this direct visualization of how antenna arrays work (shown recently at the 2016 IEEE International Symposium on Phased Array Systems and Technology).  It is almost as if you were to put on a pair ‘microwave goggles’ and looked into the antenna array!

MIT Lincoln Laboratory Phased Array Demonstrator, on display at the 2016 IEEE Intl. Symposium on Phased Array Systems and Tech.MIT Lincoln Laboratory Phased Array Demonstrator, on display at the 2016 IEEE Intl. Symposium on Phased Array Systems and Tech.

A plexiglass duplicate of an actual phased array antenna system built by MIT/LL is stuffed with NEO Pixel LEDs.  Each antenna element is illuminated by two NEO Pixels, where this is a dual-polarized phased array using one LED for vertical and another for horizontal polarization.

The color of each NEO Pixel is mapped to phase of what its respective antenna element should be to project a beam of microwave energy in any given direction and this beam pattern is plotted by the flat-screen monitor next to the array.

The brightness of each LED is proportional to transmit power out of its respective antenna element. The array supports amplitude tapering to synthesize low sidelobe beam patterns and numerous advanced array modes.

With this visualization system, you can manually move the antenna beam around with a joystick and view the lighted pattern and beam plots changing in real-time, providing an instant and intuitive understanding of phased array beam steering and beam patterns.  Absolutely amazing!

Summary

Phased array antenna systems will play a central role in our modern lives facilitating greater wireless bandwidths, making airline travel safer, and weather prediction more accurate.  Compelling visualizations like the array shown here will facilitate widespread understanding of electromagnetics and modern antenna techniques.

Acoustic Levitation with a Twist

Don’t blame us for the click-baity titles in the source articles about this handheld “acoustic tractor beam”. You can see why the popular press tarted this one up a bit, even at the risk of drawing the ire of Star Trek fans everywhere. Even the journal article describing this build slipped the “tractor beam” moniker into their title. No space vessel in distress will be towed by [Asier Marzo]’s tractor beam, unless the aliens are fruit flies piloting nearly weightless expanded polystyrene beads around the galaxy.

That doesn’t detract from the coolness of the build, revealed in the video below. There’s no tutorial per se, but an Instructables post is promised. Still, a reasonably skilled hacker will be able to replicate the results with ease straight from the video. Using mostly off the shelf hardware, [Marzo] creates a bowl-shaped phased array of ultrasonic transducers driven by an Arduino through a DC-DC converter and dual H-bridge driver board to boost the 40 kHz square waves from 5 Vpp to 70 Vpp. By controlling the phasing of the signals, the tractor beam can not only levitate small targets but also move them axially. It looks like a lot of fun.

Acoustic levitation is nothing new here – we’ve covered 3D acoustic airbending, as well as an acoustic flip-dot display. Being able to control the power of sound waves in a handheld unit is a step beyond, though.

Thanks to [Brian Andersen] and [Sak] for the nearly simultaneous tips.

Pretty Fly for a DIY Guy

Milling machines can be pretty intimidating beasts to work with, what with the power to cut metal and all. Mount a fly cutter in the mill and it seems like the risk factor goes up exponentially. The off-balance cutting edge whirling around seemingly out of control, the long cutting strokes, the huge chips and the smoke – it can be scary stuff. Don’t worry, though – you’ll feel more in control with a shop-built fly cutter rather than a commercial tool.

Proving once again that the main reason to have a home machine shop is to make tools for the home machine shop, [This Old Tony] takes us through all the details of the build in the three-part video journey after the break. It’s only three parts because his mill released the Magic Smoke during filming – turned out to be a bad contactor coil – and because his legion of adoring fans begged for more information after the build was finished. But they’re short videos, and well worth watching if you want to pick up some neat tips, like how to face large stock at an angle, and how to deal with recovering that angle after the spindle dies mid-cut. The addendum has a lot of great tips on calculating the proper speed for a fly cutter, too, and alternatives to the fly cutter for facing large surfaces, like using a boring head.

[ThisOldTony] does make things other than tooling in his shop, but you’ll have to go to his channel to find them, because we haven’t covered too many of those projects here. We did cover his impressive CNC machine build, though. All [Tony]’s stuff is worth watching – plenty to learn.

Hacked Television Uses No Power In Standby Mode

How much effort do you put into conserving energy throughout your daily routine? Diligence in keeping lights and appliances turned off are great steps, but those selfsame appliances likely still draw power when not in use. Seeing the potential to reduce energy wasted by TVs in standby mode, the [Electrical Energy Management Lab] team out of the University of Bristol have designed a television that uses no power in standby mode.

The feat is accomplished through the use of a chip designed to activate at currents as low as 20 picoamps.  It, and a series of five photodiodes, is mounted in a receiver which attaches to the TV. The receiver picks up the slight infrared pulse from the remote, inducing a slight current in the receiving photodiodes, providing enough power to the chip which in turn flips the switch to turn on the TV. A filter prevents ambient light from activating the receiver, and while the display appears to take a few seconds longer to turn on than an unmodified TV, that seems a fair trade off if you aren’t turning it on and off every few minutes.

While some might shy away from an external receiver, the small circuit could be handily integrated into future TVs. In an energy conscious world, modifications like these can quickly add up.

We featured a similar modification using a light-sensitive diode a few years ago that aimed to reduce the power consumption of a security system. Just be wary of burglars wielding flashlights.

[Thanks for the submission, Bernard!]

Santa Knows If Your Contact Form Uses PHPMailer < 5.2.18

PHPMailer, one of the most used classes for sending emails from within PHP, has a serious vulnerability in versions less than 5.2.18 (current version). The security researcher [Dawid Golunski] just published a limited advisory stating that PHPMailer suffers from a critical flaw that might lead an attacker to achieve remote code execution in the context of the web server user. PHPMailer is used by several open-source projects, among them are: WordPress, Drupal, 1CRM, SugarCRM, Yii and Joomla. A fix has been issued and PHPMailer is urging all users to upgrade their systems.

To trigger this vulnerability (CVE-2016-10033) it seems that the attacker only has to make the web application send out an email using the vulnerable PHPMailer class. Depending on the application itself, this can be accomplished in different ways, such as contact/feedback forms, registration forms, password email resets and so on.

Upon a quick diff analysis, we found that the vulnerable code seems to lie in the following lines of the class.phpmailer.php:

Version 5.2.17

if (!empty($this->Sender)) {
  $params = sprintf('-f%s', $this->Sender);
}
if ($this->Sender != '' and !ini_get('safe_mode')) {
  $old_from = ini_get('sendmail_from');
  ini_set('sendmail_from', $this->Sender);
}

Version 5.2.18

if (!empty($this->Sender) and $this->validateAddress($this->Sender)) {
  $params = sprintf('-f%s', escapeshellarg($this->Sender));
}
if (!empty($this->Sender) and !ini_get('safe_mode') and $this->validateAddress($this->Sender)) {
  $old_from = ini_get('sendmail_from');
  ini_set('sendmail_from', $this->Sender);
}

From the code above we can get an idea where the bug comes from. The researcher [Dawid Golunski] claims to have developed a working Remote Code Execution (RCE) Proof of Concept (PoC) exploit and that he will publish it at a later date, in order to give users time to upgrade their systems.

So… sysadmins, what are you waiting for? Go and upgrade, if Santa does not sleep neither should you…

Modified Servo Adds Focus Control to Telescope

Scanning the heavens with a telescope is a great way to spend long, clear winter nights, but using a manual telescope can get to be a drag. A motorized mount with altitude and azimuth control is basic equipment for the serious observer, but adding a servo to control the focus of your telescope is one step beyond your average off-the-shelf instrument.

Having already motorized the two axes of the equatorial mount of his modest telescope as a senior project, [Eric Seifert] decided to motorize the focus rack as well. His first inclination was to use a stepper motor like he did on the other two axes, but with a spare high-torque servo at hand, he hacked a quick proof-of-concept. The servo was modified for continuous rotation in the usual way, but with the added twist of replacing the internal potentiometer with an external linear pot. Attached to the focus tube, the linear pot allows [Eric] to control the position and speed of the modified servo. Sounds like controlling the focus will be important to [Eric]’s planned web interface for his scope; we’ll be looking for details on that project soon.

We like the simplicity of this solution, and it’s a trick worth keeping in mind for other projects.  But if fancy steppers and servos aren’t your thing, fear not — astrophotography is as easy as slapping a couple of boards together with a hinge.

Gecho Pocket Synth Looper

[Mario] wrote us with his synthesizer project that’s currently up on Kickstarter. It looks like a good amount of fun to play with, as you can see in the video on the Kickstarter page. But it’s also built to be easily hackable.

On the hardware front, it’s a tiny four-layer board that’s crammed with parts. At the core is an STM32F4 microcontroller and a DAC. Indeed, the build was inspired by other folks’ work on the STM32F4 Discovery dev kit that has been used to make some pretty interesting synthesizer devices. [Mario]’s version adds two stereo headphone outputs, two microphone inputs, two IR reflective distance sensors used as control inputs, some buttons, and a ton of LEDs. And then it makes good use of all of them.

The firmware isn’t open source yet (poke! poke!) but it looks like it’s going to be. On his blog, [Mario] works through an example of adding a drum machine into the existing firmware, so it looks like it’ll be hackable.

Squeezing a lot of DSP functionality out of a single microcontroller is a feat. On a similar chip from a different manufacturer, [Paul Stoffregen]’s Teensy Audio Library could also be made to do a lot of the same things. But the real beauty of the Gecho project is that it has some interesting hardware features already built in and ready to go. It wouldn’t be a bad launching pad for your own musical or audio explorations.

Ask Hackaday: Computing Square Roots on FPGA?

Hackaday reader [nats.fr] wrote in with some code from a project that resizes a video stream on the fly using an FPGA. Doing this right means undoing whatever gamma correction has been applied to the original stream, resizing, and then re-applying the gamma. Making life simpler, [nats.fr] settled on a gamma of two, which means taking a bunch of square roots, which isn’t fast on an FPGA.

[nats]’s algorithm is pretty neat: it uses a first-stage lookup to figure out in which broad range the value lies, and then one step of Hero’s algorithm to refine from there. (We think this is equivalent to saying he does a piecewise linear interpolation, but we’re not 100% sure.) Anyway, it works decently.

Of course, when you start looking into the abyss that is special function calculation, you risk falling in. Wikipedia lists more methods of calculating square roots than we have fingers. One of them, CORDIC, avoids even using multiplication by resorting to clever bitshifts and a lookup table. Our go-to in these type of situations, Chebyshev polynomial approximation, didn’t even make the cut. (Although we suspect it would be a contender in the gamma=1.8 or gamma=2.2 cases, especially if combined with range-reduction in a first stage like [nats.fr] does.)

So what’s the best/fastest approximation for sqrt(x) for 16-bit integers on an FPGA? [nats.fr] is using a Spartan 6, so you can use a multiplier, but division is probably best avoided. What about arbitrary, possibly fractional, roots?

Automated Vacuum Lettuce Seed Placement

[Jethro Tull] is a name you may well associate with a 1970s prog/folk rock band featuring a flautist, but the original [Tull] was an inventor whose work you benefit from every day. He was a British lawyer and landowner who lived over the turn of the 18th century, and who invented among other things the mechanical seed drill.

Were [Tull] alive today he would no doubt be impressed by the work of [Akash Heimlich], who has created an exquisite vacuum seed placer for his rooftop hydroponic lettuce farm. Unlike the continuous rows of seed on the Berkshire earth of [Tull]’s farm, the lettuce seed must be placed in an even grid on a foam substrate for the hydroponic equivalent. This was an extremely tedious task when done by hand, so [Akash] set about automating the process with a vacuum seeder that is a thing of beauty.

It uses a simple yet effective mechanism involving a row of pipettes connected to a vacuum line, that are rotated over a vibrating hopper of seeds from which each one collects a single seed, before being rotated back over the foam where the seeds are dropped in a neat row through 3D-printed funnels. The foam is advanced, and the process is repeated until there is a neat grid of seeds. In only four minutes it can deliver 150 seeds, reducing several hours work into under half an hour.

The whole machine is controlled by an Arduino, with a couple of stepper motors to move foam and pipettes alongside the vibrator motor. You can see its operation in the video below the break.

We’ve covered a huge number of hydroponic projects in our time, though as far as we can see this is our first seeder. Most recently we’ve shown you a couple of vertical hydroponic systems using PVC pipe, one for growing plants as pollution biomarkers, and another back-garden system that is solar-powered.

Hackspace U

No Timmy, we're not preparing you for a life of mindless drudgery! PD, via Wikimedia Commons.No Timmy, we’re not preparing you for a life of mindless drudgery! PD, via Wikimedia Commons.

It’s funny, how obsessed we are with qualifications these days. Kids go to school and are immediately thrust into a relentless machine of tests, league tables, and exams. They are ruthlessly judged on grades, yet both the knowledge and qualifications those grades represent so often boil down to relatively useless pieces of paper. It doesn’t even end for the poor youngsters when they leave school, for we are now in an age in which when on moving on from school a greater number of them than ever before are expected to go to university. They emerge three years later carrying a student debt and a freshly-printed degree certificate, only to find that all this education hasn’t really taught them the stuff they really need to do whatever job they land.

A gold standard of education is revealed as an expensive piece of paper with a networking opportunity if you are lucky. You need it to get the job, but in most cases the job overestimates the requirement for it. When a prospective employer ignores twenty years of industry experience to ask you what class of degree you got twenty years ago you begin to see the farcical nature of the situation.

In our hackspaces, we see plenty of people engaged in this educational treadmill. From high schoolers desperately seeking to learn something other than simply how to regurgitate the textbook, through university students seeking an environment closer to an industrial lab or workshop, to perhaps most interestingly those young people who have eschewed university and gone straight from school into their own startups.

The Hackspace As A Learning Environment

This book is a lifesaver in a lecture theatre, but not so much in a hackspace.This book is a lifesaver in a lecture theatre, but not so much in a hackspace.

All these people and many others come to our spaces to learn things. It’s not a replacement for an engineering degree, after all you won’t learn the concepts in [Stroud] alongside the 3D printer, but in a lot of cases what can be learned is equally as useful as anything you will learn in a lecture theatre. Through access to the facilities and probably more importantly the rest of the membership of a thriving hackspace, you can learn about manufacturing. Taking a hobby project, turning it into a prototype, where to go next when you want to turn it into a product, and even the mechanics of setting up your own startup.

Universities try to expose students to some of these things, but it’s sadly the case that they get lost in the noise as they also try to hammer all that maths or digital logic into their heads. Meanwhile at the hackspace these and many more useful skills are yours for the taking, and members proceed to heap their plates with this knowledge opportunity.

The trouble with picking up knowledge in a hackspace is that you don’t have anything to show for it afterwards. We’re back to the first paragraph above again: without a bit of paper accompanying it, a piece of knowledge is a devalued currency to a lot of people who unfortunately matter. It’s useful to talk about it when you get to that job interview, but your résumé won’t have it in the list of qualifications so when it has to get past the administrative staff who open the envelopes and make the first cut you’ll go straight in the round file. Put it in the work experience list and it won’t mean much to them.

Meaningful Bits Of Paper

So what’s to be done? As a hackspace director I can issue a bit of paper: “[Jane] has used our hackspace to design her electronic product, she has brought it through three rounds of prototypes making printed circuit boards and 3D printed enclosures, she waged a succesful Kickstarter campaign to launch it and built her own online shop to sell it afterwards, signed [Jenny List], Director”. But sadly my word doesn’t stand for much, and it wouldn’t be taken seriously if presented as a qualification.

If you were to ask me, I’d make a case for a centralized certification scheme for skills gained in our environment. If you can create a CAD model and 3D print it, or if you can design a PCB and reflow a batch of boards, you should be able to say so in a manner that will be recognized, or at least is verifiable. The snag is of course, how might a loosely affiliated network of independent and often cash-strapped hackspaces produce a certification scheme with the required traceability and rigor to be taken seriously as a qualification? It’s not an easy task at all, verifying a qualification in that environment.

Perhaps it might be achieved by reference to multiple sources, for example if someone learns to use a 3D printer with us then they could only apply for a certificate to say so when it is accompanied by evidence that they have demonstrated that skill to a couple of other hackspaces also participating in the scheme. Cumbersome and inconvenient in that it necessitates travel, but at least it would provide some rigor.

There are multiple functions a hackspace fulfills aside from the obvious one of being a workshop. Community, support group, knowledge base, and many more. Why shouldn’t “education hub” be added to that list? Does your space find itself in this role? How might the suggestion above about how it could be formalised be improved? Let us know in the comments.


[Jenny List] is a director of Oxford Hackspace when she is not writing for Hackaday.

33C3 Starts Tomorrow: We Won’t Be Sleeping for Four Days

Possibly the greatest hacker show on Earth, the 33rd annual Chaos Communication Congress (33C3) begins Tuesday morning in Hamburg, Germany. And Hackaday will be there! Contributing Editor [Elliot Williams] is taking the night train up and will be trying to take it all in for you. The schedule looks tremendous.

If you can’t make it, don’t fret. There will be live streaming, and the talks are usually available in preliminary edit for viewing or download just a few minutes after they finish. It’s even cooler to watch the talks with friends, though. Every hackerspace with a video projector could be playing along, live or after the fact. Pick some cool talks and have a “movie night”.

elliot_williams_head_2_square_fuzzIf you’re going to be in Hamburg, and you want to show us something cool, tell us that something is NOTAHACK!1!! in person, or even just say “Hi”, we’ll be wandering around from talk to talk and session to session just like you, only with a backpack full of Hackaday stickers.

If there’s anything you think we should see, post up in the comments. If there’s enough call for it, we’ll have a Hackaday meetup once we can figure out a good time and location. Bring us a cool hack, and we’ll document it on the spot! Our DECT phone number will be edited right here on the 27th.

Off-Grid Travel — Setting Up a Solar System

When you’re living out of a vehicle, or even just traveling out of one, power quickly becomes a big concern. You need it for lights, to charge your various devices, to run your coffee maker and other appliances, and possibly even to store your food if you’ve got an electric refrigerator. You could do what many RV owners do: rely on campgrounds with electrical hookups plus a couple of car batteries to get you from one campground to the next. But, those campgrounds are pricey and often amount to glorified parking lots. Wouldn’t it be better if you had the freedom to camp anywhere, without having to worry about finding somewhere to plug in?

That’s exactly what we’re going to be covering in this article: off-grid power on the road. There are two major methods for doing this: with a portable gas generator, or with solar. Gas generators have long been the preferred method, as they provide a large amount of power reliably. However, they’re also fairly expensive, cumbersome, noisy, and obviously require that you bring along fuel. Luckily, major advances in solar technology over the past decade have made it very practical to use solar energy as your sole source of electricity on the road.

The Goal

Whenever you’re starting a new project, it’s always important to clearly define your goal. This is never more true than when you’re going to be relying on the outcome for your personal well being. So, first, we’re going to discuss what the average overland traveler wants and needs for power. The most obvious first requirement is lighting.

Luckily, efficient LED lighting is pretty ubiquitous these days. It’ll probably take less than 50 watts to completely light up your vehicle with 12V LED lighting. Most modern televisions will use a similar amount of energy.

Next up, you’re going to want to be able to run at least a few basic appliances. For us here at Hackaday, a coffee maker is at the top of that list. Unfortunately, coffee makers use a lot of power — a Keurig can use up to 1500 watts while heating up. Other appliances use similarly high amounts of power. A microwave will use roughly 1200 watts while running, and a toaster oven uses even more.

Characterizing Your Needs

This chart, provided by WAGAN, lists some common appliances and their power consumption (though TV power consumption has been dramatically reduced in recent years)This chart, provided by WAGAN, lists some common appliances and their power consumption (though TV power consumption has been dramatically reduced in recent years)

Then there are the really high energy consumption appliances, such as air conditioners and heaters. Both of these require a lot of power to run, and also need to be run for long periods of time. While it is technically possible to run both from a solar setup, it would require a massive investment in solar panels and batteries for storage. In that case, a generator would be more cost-effective.

So, for the sake of brevity, let’s say you’ve decided to forego the air conditioner (or will only use it when you have access to shore power). The heater, water heater, and refrigerator will all be run off of propane. That leaves you with a setup that will only be consuming ~100 watts most of the time, and occasionally will peak close to 2,000 watts when the appliances are in use. Now let’s talk about what you’ll need to buy to make that happen.

The Equipment

There are four main components that are going to be going into your solar system: a converter, an inverter, batteries, and the solar panels themselves. Virtually all RVs (and vehicles in general) are set up to run 12V DC electricity. This is so they can be run directly from something like a standard car battery. Most of your appliances and other household devices, however, are powered by the 120V AC you generally get from your wall outlets.

Inverter

This is where the inverter comes into play. It takes 12V DC from your batteries and turns it into 120V AC, so that you can run all of your normal household devices. That said, the process isn’t perfectly efficient, which means you should try to use the 12V system as much as you can (for instance, for the LED lighting). Inverters will also consume some power even when nothing is being run through them, so it’s best to shut them off completely when not in use.

As we covered in the last section, you’ll probably want an inverter capable of 1,500 to 2,000 watts of continuous output. Not all inverter output is the same even though the power ratings may match. Pure Sine Wave inverters are more expensive, but provide power that is much closer to “real” AC power available from an outlet. Some appliances will have problems running off of the less expensive Modified Square Wave inverters (and could possibly even be damaged). If you’re not sure which you’ll need, it’s probably best to spend a little more on a Pure Sine Wave model.

Converter

The opposite of an inverter is a converter — it turns 120V AC into 12V DC. These are necessary for charging your batteries from shore power (a mains outlet), and for running your 12V system from shore power. Virtually all RVs will have a converter already built into the electrical system, but you’ll need to purchase one if you don’t already have one and want the option to charge your batteries from an outlet.

Solar Panels

With the solar panels themselves, you’re really only limited by how much space you have available and how much money you have. The more watts you can afford (and fit onto your rig), the better. While some panels are slightly more efficient than others, they’re all pretty close to each other right now. Which means it’s mostly about how many square feet you have available and how much money you’re willing to spend. Most people will need 150 watts at a minimum, with something like 600 watts being ideal.

Earthroamer, a leader in off-grid expedition vehicles, provides a 3,000 watt solar panel array on their XV-LTS model.Earthroamer, a leader in off-grid expedition vehicles, provides a 1,200 watt solar panel array on their XV-LTS model.

How much you’ll actually need is pretty difficult to guess, however. A 150 watt panel, for example, will only actually provide 150 watts under perfect conditions (clear day, sun directly overhead, etc.). In general though, you can probably expect to actually get 1/3 to 1/2 of the rated watts during daylight hours on average. This will obviously vary based on weather conditions, time of year, and how you position the panels. You’ll also need a solar charger to go with the panels, but these are inexpensive and are generally just matched to the wattage of your solar array.

Batteries

Finally, you’re going to need batteries with which to store all of this power. All of this equipment was designed specifically to run off of standard 12V car batteries, but they aren’t actually the most ideal battery for the application. Car batteries are meant to provide a huge amount of starting amperage (to start your car’s engine), and aren’t meant for the kind of long slow drain you want for a solar setup. There are batteries designed specifically for solar setups, but a solution that’s both ideal and economical is to use golf cart batteries.

Golf cart batteries are mass produced and optimized for deep cycle use.Golf cart batteries are mass produced and optimized for deep cycle use.

Golf cart batteries are good at storing a lot of energy and are generally inexpensive. However, most come in 6V instead of 12V. That means that you’ll need at least two wired in series to get to 12V (multiple pairs can be wired in parallel). You’ll want to choose the number of batteries based on your expected usage. A good rule of thumb is to have enough to run your system for a day or two without recharging, which should be enough to carry you through situations where your solar panels aren’t outputting much power (in bad weather, for instance).

The Setup

There are three ways to charge the batteries on this system:

  1. With the solar panels, which will always be happening passively when there is enough sunlight to generate some current.
  2. From your vehicle’s alternator, which you only want happening when the vehicle is actually running (to avoid draining your car battery).
  3. With shore power, which is ideal for quickly charging the batteries when you’ve got access to mains electricity.

Charging your batteries with the solar panels will happen completely in the background. Your solar charger should always been connected to the batteries, that way you’ll be gathering and storing energy anytime there is sunlight. If your batteries are already full, the solar charger will simply keep them topped off with a trickle.

Taking advantage of your car’s alternator to charge the batteries is similarly simple. If your vehicle is wired to pull a trailer, then you’ve already got what you need. Just connect a plug with 12V and ground wired up, and have those wires run into your battery bank. Whenever the vehicle is running, some power from the alternator will be used to charge your batteries. For most vehicles, this won’t be a huge amount of power, but it’s good to take advantage of everything you have available.

Looper

Using shore power gets a little more complicated, because it’s easy to create a loop that will run your charge/discharge system constantly. The converter will take mains electricity (120V AC “shore” power), and convert it into 12V DC to charge the batteries and run your 12V electronics. However, if your inverter is connected, it’s going to attempt to turn that right back into 120V AC. Furthermore, if the inverter output isn’t isolated from your shore power circuit, you’re going to create a loop where the inverter then feeds the converter, and the converter feeds the inverter. This is a never-ending loop that will, at best, drain your batteries, and at worst could damage your equipment.

This means that your entire system essentially needs to have two “modes” — one for when you’re connected to shore power, and one for when you’re not. When you’re connected to shore power, that should feed directly into your vehicle’s 120V system (to power your appliances) and into the converter to charge your batteries and run the 12V system. When you’re disconnected from shore power, the inverter should be reintroduced (and the converter disconnected), and your 120V system should be run from that.

You can handle that kind of circuit setup in one of three ways: manually (physically unplugging the inverter when you plug into shore power), with a switch, or with a relay. Manually is, obviously, the cheapest and simplest, but you carry the risk of forgetting to do it. And, depending on where your equipment is stored, it might be difficult to physically get to. A switch is a good option for solving the latter problem, but you still have to remember to flip it when you connect or disconnect from shore power. A relay solves both problems, and requires no effort on your part, but you’ll need the electrical know-how to wire it up (which shouldn’t be a problem for Hackaday readers).

A complete mobile system overview [Image Source: Living In My Car]A complete mobile system overview [Image Source: Living In My Car]No matter which option you choose, what’s important is that the inverter and converter should never be running at the same time. When you’re connected to shore power, the inverter should be disconnected and the converter connected, and your 120V circuit should be connected directly to shore power. When you’re disconnected from shore power, the inverter should be connected and the converter disconnected, and your 120V circuit should be connected to the inverter’s output.

On the subject of output, we’ve already mentioned that you’re going to have two primary circuits: a 12V circuit and a 120V circuit. The 12V circuit will be connected directly to the batteries, and will feed anything that runs on 12V (LED lights, water pumps, heater igniters, etc). This circuit can use inexpensive fuse blocks designed for cars or RVs. Keep in mind that wire gauge is important here, especially if you’re going to be running a lot on the 12V circuit, so choose your wire size appropriately for the amperage and wire length.

The 120V circuit will be connected to the inverter’s output (and switched to mains when you’re on shore power). This will power any of your household type devices. The inverter itself will have it’s own fuses, but keep in mind that those won’t be part of the circuit when you’re on shore power. So, it’s prudent to fuse the entire circuit after the point where it switches to mains electricity.

The Execution

As described, this system is designed to be as passive as possible. If everything is set up properly, you shouldn’t have to do anything other than use your appliances and devices like you would expect. That’s especially true if you used a relay for switching to shore power. In that case, the only thing you have to do is plug your rig into a mains outlet if it’s available. Everything else should be humming along happily in the background.

That said, there are a few things you should pay attention to and check from time to time. The first seems obvious, but just be conscious of your energy usage. For example, there is no sense in brewing an entire pot of coffee if you’re only going to drink one cup. You should learn very quickly what uses a lot of power, and what you want to prioritize.

Next is basic maintenance. This kind of system actually requires very little maintenance, but it’s a good idea to occasionally monitor your batteries to make sure they’re healthy. Basically, just take a look and see if they seem to be charging and discharging consistently and predictably. You should also take the time to clean your solar panels every now and then, to make sure you’re getting as much power as you can out of them.

Finally, periodically check your wiring to make sure it’s all secure. We’re going to assume you, as a Hackaday reader, know how to properly set up wiring, but when it’s being jostled on the road it’s possible for things to come lose. The last thing you want is a fire caused by a short somewhere.

Other than that, the most important thing you can do is enjoy the freedom of off-grid travel! We’ve even covered how to build your own travel trailer if you’re itching to get on the road. Have any tips of your own, or cool stories about your travels? Be sure to share them in the comments below!

Hacking Google Daydream to work with iOS

The Google Daydream is a VR headset with a controller, and according to the folks at Google, “It’s not currently compatible with iOS and won’t be for several years probably.” OK.

This inspired [Matteo Pisani] to get to work on the protocol that it uses to speak with Android phones. Cutting to the chase, he got it working in several days.

There really wasn’t all that much to it. The controller sends data over Bluetooth, and [Matteo] noticed an “unknown” device on the network. Looking inside the data that it sent, it changed when he moved the controller. Not so unknown now! The rest of the work consisted of writing applications to test hypotheses, waving the controller around, and finding out if he was right. Read up if you’re interested in implementing this yourself.

We love protocol hacks here. From running quadcopters on your own remotes, to simply trying to turn on a lightbulb, it’s getting more and more important that we understand the various languages that our devices speak.

Massive Pixel Display Holiday Decoration

Decorating for the holidays is serious business! Finding themselves surrounded by neighbours who go big, redditor [wolfdoom] decided that this was the year to make a strong showing, and decided to build an oversized pixel LED display.

LED Pixel Holiday DisplayDemonstrating resourcefulness in their craft, [wolfdoom] found an old fluorescent light grid pattern to prevent bleed from one pixel to the next. Reusing this grid saves many hours of precision-cutting MDF — to be substituted with many hours of cutting the plastic with decidedly more room for error. Attaching the resulting grid to a sheet of plywood, and 576(!) drilled holes later, the LEDs were installed and laboriously wired together.

A Plastic light diffusing sheet to sell the pizel effect and a little help from their local maker space with the power circuit was enough to keep this project scrolling to completion — after the requisite period of basement-dwelling fabrication.

Despite some minor demotion attributed to a clumsy daughter, the massive 4×4 display remained a suitably festive decoration. For now the control system remains in [wolfdoom]’s basement, but with plans to incorporate it into the display’s frame down the road.

One of the more interesting LED matrix builds we saw this year is the one that uses 1575 beer bottles. For a more interactive holiday decorations, Halloween usually takes the cake — like this animated door knocker.

[via /r/DIY]

80-PIC32 Cluster Does Fractals

One way to get around limitations in computing resources is to throw more computers at the problem. That’s why even cheap consumer-grade computers and phones have multiple cores in them. In supercomputing, it is common to have lots of processors with sophisticated sharing mechanisms.

[Henk Verbeek] decided to take 80 inexpensive PIC32 chips and build his own cluster programmed in — of all things — BASIC. The devices talk to each other via I2C. His example application plots fractals on another PIC32-based computer that has a VGA output. You can see a video of the device in action, below.

The slave boards are simple and use wire jumpers to select a different address on the I2C bus. Each has a multi-color LED that shows when it is working on a task and when the task is complete. So from a blinking light perspective, the computer is a success.

One problem with setups like this is having an efficient way to communicate between processors. [Henk] found that I2C is the bottleneck. Even though he has 80 CPUs, he found the fractal program bogged down if you applied more than twelve processors to the job.

One nice thing about Hackaday is you never have to ask why you did something like this. The fact is, this probably isn’t very practical as a parallel supercomputer. But it is still an interesting and educational project and might be the most CPUs we’ve ever seen running BASIC together.

Clusters of Raspberry Pis, of course, are nothing new. We’ve also looked at some that are more practical.

A Beacon Suitable for Tracking Santa’s sleigh?

High-altitude ballooning is becoming a popular activity for many universities, schools and hacker spaces. The balloons, which can climb up to 40 km in the stratosphere, usually have recovery parachutes to help get the payload, with its precious data, back to solid ground safely. But when you live in areas where the balloon is likely to be flying over the sea most of the time, recovery of the payload becomes tricky business. [Paul Clark] and his team from Durham University’s Centre for Advanced Instrumentation are working on building a small, autonomous glider – essentially a flying hard drive – to navigate from 30 km up in the stratosphere to a drop zone somewhere near a major road. An important element of such a system is the locator beacon to help find it. They have now shared their design for an “Iridium 9603 Beacon” — a small Arduino-compatible unit which can transmit its location and other data from anywhere via the Iridium satellite network.

The beacon uses the Short Burst Data service which sends email to a designated mail box with its date, time, location, altitude, speed, heading, temperature, pressure and battery voltage. To do all of this, it incorporates a SAMD21G18 M0 processor; FGPMMOPA6H GPS module; MPL3115A2 altitude sensor; Iridium 9603 Short Burst Data module + antenna and an LTC3225 supercapacitor charger. Including the batteries and antenna, the whole thing weighs in at 72.6 g, making it perfectly suited for high altitude ballooning. The whole package is powered by three ‘AAA’ Energizer Ultimate Lithium batteries which ought to be able to withstand the -56° C encountered during the flight. The supercapacitors are required to provide the high current needed when the beacon transmits data.

The team have tested individual components up to 35 km on a balloon flight from NASA’s Columbia Scientific Balloon Facility and the first production unit will be flown on a much smaller balloon, launched from the UK around Christmas. The GitHub repository contains detailed information about the project along with the EagleCAD hardware files and the Arduino code. Now, if only Santa carried this on his Sleigh, it would be easy for NORAD to track his progress in real time.

A DIY Net Gun To Catch Whatever You Want

Suspicious drones hovering about your property? Burglars or other ne’er-do-well test subjects giving you trouble? Need to catch a dog that keeps meandering through your workshop? [William Osman] suggests you build yourself a pneumatic net gun that can shoot 20-30 feet to catch them all.

The net gun is built largely out of PVC pipe; the air tank — filled via a tire valve — uses adapter fittings to shrink it down to a 1″ sprinkler valve, with an air gun to act as a trigger. The net launcher is made of four lengths of pipe bent with the use of a heat gun — an Occam’s Razor solution compared to his first attempt — and is coupled to the end, while the net loads in using wooden dowels with washers as weights. It won’t trap any large game, but it will certainly net you some fun.

[William Osman] notes that you have to be sure not to mix up the corners of the net when loading or it’ll tangle itself up to the point of ineffectiveness, and to properly seal all the components to prevent lost off air pressure.

If a net gun won’t stop whatever is bothering you, a DIY railgun might do the trick.

[via /r/DIY]

Hacked Diamond Makes Two-Atom Radio

It used to be pretty keen to stuff a radio receiver into an Altoid’s tin, or to whip up a tiny crystal receiver from a razor blade and a pencil stub. But Harvard researchers have far surpassed those achievements in miniaturization with a nano-scale FM receiver built from a hacked diamond.

As with all such research, the experiments in [Marko Lončar]’s lab are nowhere near as simple as the press release makes things sound. While it’s true that a two-atom cell is the minimal BOM for a detector, the device heard belting out a seasonal favorite from [Andy Williams] in the video below uses billions of nitrogen-vacancy (N-V) centers. N-V centers replace carbon atoms in the diamond crystal with nitrogen atoms; this causes a “vacancy” in the crystal lattice and lends photoluminescent properties to the diamond that are sensitive to microwaves. When pumped by a green laser, incident FM radio waves in the 2.8 GHz range are transduced into AM fluorescent signals that can be detected with a photodiode and amplifier.

The full paper has all the details, shows that the radio can survive extreme pressure and temperature regimes, and describes potential applications for the system. It’s far from a home-gamer’s hack at this point, but it’s a neat trick and one to watch for future exploitation. In the meantime, here’s an accidental FM radio with a pretty small footprint.

Thanks to [Sine Square Saw] for the tip.

Retrotechtacular: Rocket Sleds

If you need to test rockets, missiles, or ejection-seat systems, your first instinct would be to shoot them up in the air and see what happens. But if you want data, film footage, or the ability to simply walk away from a test, you might consider running your experiment on a rocket sled.

The Holloman High Speed Test Track is a 15 km long stretch of meticulously straight railroad track located in the middle of the New Mexico desert, and bristling with measurement equipment. Today’s Retrotechtacular video (embedded below) gives you the guided tour. And by the way, the elderly colonel who narrates? He doesn’t just run the joint — he was one of the human test subjects put on a rocket sled to test the effects of high acceleration on humans. You can see him survive a run around 1:00 in.

The video isn’t all that long, but it’s slow-paced. High points include the water braking system in the first few minutes. The “momentum exchange technique” is secret code for filling the space between the tracks with water and ramming a scoop into it, throwing water forwards and thus slowing the sled down.

At 10:40, there’s an almost bizarre transition to dream-like slow motion sequences of various rockets making their runs. Great stuff. In between, there’s a lot of detail about the multiple cameras, light-break sensors, and other instrumentation that was state of the art in the 1960s.

Holloman is still in use today, as far as we know, which makes this Retrotechtacular a bit more contemporary than usual. The fastest run took place in 2003 at Mach 8.6. Not bad for some strips of metal dating back to 1949.

We can’t leave the subject of crazy rocket sleds without mentioning these mental Swedes or The Black Beetle.

Smart Projector With Built-in Raspberry Pi Zero

You’ve heard of smartphones but have you heard of smart projectors? They’ve actually been around for a few years and are sort of like a TV set top box and projector combined, leaving no need for a TV. Features can include things like streaming Netflix, browsing in Chrome, and Skyping. However, they can cost from a few hundred to over a thousand dollars.

[Novaspirit]  instead made his own cheap smart projector. He first got a $70 portable projector (800×480 native resolution, decent for that price) and opened it up. He soldered an old USB hub that he already had to a Raspberry Pi Zero so that he could plug in a WiFi dongle and a dongle for a Bluetooth keyboard. That all went into the projector.

Examining the projector’s circuit board he found locations to which he could wire the Raspberry Pi Zero for power even when the projector was off. He lastly made the Raspberry Pi dual-bootable into either OSMC or RetroPie. OSMC is a Linux install that boots directly into a media player and RetroPie is a similar install that turns your Raspberry Pi into a gaming machine. You can see a timelapse of the making of it and a demonstration in the video after the break.

This isn’t the only cool thing [Novaspirit] has done with one of these $5 Raspberry Pi Zeros. We also saw him turn one into a USB stick for plugging into a laptop, using the USB connection as an Ethernet connection.

Another Desktop LED Xmas Tree!

We love it when someone takes inspiration from one of our posts and comes up with their own twist on it. [Matthew] liked one builds he saw on Hackaday so much, he built his own LED desktop Xmas tree!

[Matthew] was inspired by [designer2k2]’s DIY desktop Xmas tree that was posted in October. To get started, he found a set of concentric WS2812 rings over on Ali Express. The five rings total 93 LEDs, plus a single WS2812 for the top of the tree. He also got a laser cut tree model from Thingiverse and had it cut, combining the LED rings with the tree in the final product

The whole thing running on a Digispark USB Development Board from DigiStump, the same as the original project. There aren’t many details in the video, but [Matthew] has put links to where he got the rings and the tree, the laser cutting service, a link to the DigiStump website as well as a link to [designer2k2]’s original tree project. There’s no source code yet, but [Matthew] says a link to it is coming along with some more pictures.

Animatronic Cosplay Wings

In recent years, Cosplay as a hobby has seen improvement in the props department by leaps and bounds. Thanks in part due to the rise of the Maker culture and the easy availability of design and manufacturing tools and processes. Case in point is this awesome set of Animatronic Wings that programmer [Nelson Stoldt] built for his daughter who wanted to be Nightmare Moon.

[Nelson] had no idea what he’d gotten himself in to when he answered “Sure, I can do that”. Making motorized cosplay wings that open up to 8 feet wide and close again at the flick of a switch without weighing a ton is not a trivial project. The final rig did end up tipping the scales at just over 9 kgs, but we guess that’s a load that Cosplayers are used to hauling around.

Using a nifty program called Linkage, he played around with a few different design approaches until he found a mechanism that worked well. If you ever want to build one of [Theo Jansen]’s Strandbeest, give this program a spin. Armed with this information, and a spreadsheet to help determine the exact length of each linkage element, he modelled the project in Sketchup. The wings are operated by a scissor mechanism that is driven by a motorized screw operated sliding carriage. Wing position is measured by a potentiometer coupled to one of the wing elements. Basically, he just built a huge, powerful servo.

The linkage mechanism was built out of Aluminum bars. This part of his blog — measuring, marking, cutting, drilling, tapping, sanding, sawing — sounds like a Harbour Freight advert, but we’ll let that pass. He cut an acrylic sheet, heated it in an oven, and then bent it to shape to fit the back of the cosplay dress. Attached to the body using straps, this acrylic backpack has a kind of hook mechanism that allows the main wings to be easily clipped in and removed. Handy since they weigh a lot.

wings-mechanism-optimizedUnfortunately, after adding all of the skin and feathers to the wings, the original motor turned out to be underpowered. A cordless drill was then hacked to help power the wings (maybe he didn’t get the memo about Harbor Freight chainsaws?). The electronics are pretty simple, an Arduino Uno with two input switches and a DPDT relay for controlling the motor direction. A beefy FET recovered from the cordless drill helped drive the new motor. The dual switches helped ensure safety. With the master switch pressed,  click slave switch once to raise, or twice to lower. While the motor was moving, a click on any switch would stop it immediately.

There were some last minute hiccups with the wings not opening fully, but some quick code edits solved the problem. His daughter showed off her animatronic wings and went on to win the Best in Show prize, so the effort totally paid off.

3D Printed Circuit Boards… Sort Of

Comedian Demetri Martin does a bit about the phrase “sort of”. He says:

“Sort of’ is such a harmless thing to say… sort of. It’s just a filler. Sort of… it doesn’t really mean anything. But after certain things, sort of means everything. Like… after “I love you”… or “You’re going to live.”

SCADboard is an OpenSCAD library that lets you create 3D printable circuit boards…sort of. The library lays out like a breadboard with two bus bars on each side and a grid of rows and columns. OpenSCAD modules provide a way to create a board, ICs, LEDs, wires and other fundamental components. You set a few initial variables (like the board thickness) then your code looks like this:

 wire(1,bln,1,e, neg); // Neg left trace to LED
 led(1,e+1, 1,e+2, yellowled); // LED
 wire(1,f, 1,i, pos); // LED Pos
 wire(1,j, 1,brp, resistor); // Resistor
 
 wire(3,c,3,h, pos); // Cap Pos
 wire(4,c,4,h, neg); // LED Resistor

The catch? You can print it, but there’s no electrical conductivity. There are little troughs for you to include wires. The authors suggest you twist the wires together. You can solder them, but if you do, you have to be careful not to get the plastic board hot enough to melt. That might take a little technique or some heat sinking. It certainly requires a steady hand and fast soldering. We thought about covering the printed substrate with Kapton tape and punching through it to pass the wires through holes, but we aren’t sure how well that would work in practice.

Apparently, though, it does work. They did a layout of a simple Arduino board as a proof of concept. It is a circuit board…sort of. [Brian’s] been doing his series on making a PCB in everything, but we doubt this will make muster. Then again, you don’t really have to make them at all anymore.

Clear the Air Around Your CNC Router with a Custom Dust Shroud

Using a CNC router is a dusty business if your material of choice is wood. Sure, you can keep things tidy by chasing the cutter around the table with a shop vac, but that sort of takes the fun out of having a machine that can make cuts without you. The big boy machines all have integrated dust collection, and now you can too with this 3D-printed CNC router dust shoe.

Designed specifically for the X-Carve with a DeWalt 611 router, [Mark Edstrom]’s brush is a simple design that’s almost entirely 3D printed. The shroud encloses the router body and clamps to the mounting bracket, totally surrounding the business end of the machine. The cup is trimmed with a flexible fringe to trap the dust and guide it to the port that fits a small (1-1/4″ diameter) shop vac hose. The hose is neatly routed along the wiring harness, and the suction is provided by a standard shop vac.

Files for the cup are up on Thingiverse; we suspect it’d be easy to modify the design to work with other routers and dust collectors. You might even find a way to shroud a laser cutter and capture the exhaust with a DIY filter.

LED Tetris Table

No hackspace is complete without an arcade game project or two. Usually these projects are time-worn generic cabinets scarred by the frustrated kicks of a million teenagers, the decades-old Japanese CRT monitors inside of which are ready to shuffle off this mortal coil. You are lucky if you catch them on a rare moment of functioning, and their owners are always hovering ready to attend to any soon-to-expire electronics.

York Hackspace have done things a little differently though. Their member [John] has an arcade game project, but instead of an aged cabinet he’s produced his own tabletop game with an array of multicolour addressable LED strips powered by a Raspberry Pi. Each LED sits in its own foam cell under the translucent surface, so it forms a low resolution color block display.

It’s a Tetris game in its first incarnation, but there is also a copy of Snake underway for it. If it catches your attention you can write your own games, because all its resources are available in a GitHub repository.

This is one of many Tetris interfaces we’ve seen over the years. Largest was probably this skyscraper, but this oscilloscope version is particularly well-executed. One of our most recent forays into Tetris-land though is also one of the most technically interesting, a 446-byte implementation in a master boot record.

Detecting Water With and Without Headaches

In Texas — at least around Houston — we don’t have basements. We do, however, have bilges. Both of these are subject to taking on water when no one is paying attention. A friend of mine asked me what I thought of an Instructable that showed how to make a water sensor using a few discrete components. The circuit would probably work — it relied on the conductivity of most water to supply enough current to a bipolar transistor’s base to turn it on.

It is easy to overthink something like this, so I told my friend he should go with something a little more old-fashioned. I don’t know the origin of it, but it is older than I am. You can make a perfectly good water detector with things you probably already have around the house. My point isn’t that you should (or shouldn’t) construct a homemade water sensor. My point is that you don’t always need to go to the high-tech solution.

On the other hand, this is Hackaday, so I’m sure you want to know how to hack a water sensor out of common household items. The picture probably tells you the story anyway, but if not, read on.

What Do You Need?

The heart of the water sensor is a spring clothes pin. You also need two flat metal pieces. I’ve seen it done with pennies but you could probably use a couple of washers or pieces of scrap metal. I’ve even seen it done with aluminum foil, but I don’t recommend it. There’s one critical piece left: an aspirin. You could probably use some other things, but it has to be something hard enough to keep the clothespin open, but will also dissolve when in contact with water.

You can figure out the rest. You connect wire to the metal contacts, make a sandwich with the aspirin in the middle of the contacts and clamp it together with the clothes pin. If detecting water isn’t your thing, you might enjoy [American Hacker’s] video (see below) that uses the same idea to detect when a door opens.

More Simple Sensors

Anti-static foam, wire, Plasti Dip for an analog pressure sensorAnti-static foam, wire, Plasti Dip for an analog pressure sensor

The aspirin and clothes pin trick is just one way to make a simple sensor. Conductive foam works well as a pressure transducer (especially if you use a little Plasti-Dip to seal it). A lot of sensors use the property of another component (like this temperature sensor). Foil seems to be a common component, too.

Many times, a component made to create something can also sense it, as odd as that sounds. For example, LEDs can act as light sensors. A speaker can work as a microphone (or, you can rip the magnet out of it, steal a relay coil, and make a magnetic speed sensor).

Rant On

If you think about it, the point I’m making is one we often see in the comments for Hackaday posts. No, not “That’s not a hack.” I’m thinking more of the latest Raspberry Pi project that turns a light on when it gets dark that will elicit a lot of comments about how you could do that with a 2N2222 (or an op amp, or a 555, or whatever your weapon of choice is).

Generally, we don’t mind projects like that. People don’t need a program that prints “Hello World!” but it is a good way to get familiar with a programming language. By the same token, sometimes doing a simple project with an Arduino, a Raspberry Pi, or an FPGA is more about getting familiar with the development environment and how to apply the tool.

On the other hand, your LED blinker doesn’t need a 2 GHz CPU with 32 GB of RAM running an RTOS. My point with these sensors is the same: there are times you really do need a sensitive, precise sensor. Most of the time you need a lot less. If you aren’t going for an educational project, take some time to think about if you are using a shovel to put sugar in your coffee.

Your Turn: Homemade Sensors

There are lots of ways to make simple sensors. Your turn. What’s your favorite do-it-yourself sensor? Drop a note in the comments and let us know what sensors you’ve hacked out of improbable things.

High-Quality Film Transfers with this Raspberry Pi Frame Grabber

Untold miles of film were shot by amateur filmmakers in the days before YouTube, iPhones, and even the lowly VHS camcorder. A lot of that footage remains to be discovered in attics and on the top shelves of closets, and when you find that trove of precious family memories, you’ll be glad to have this Raspberry Pi enabled frame-by-frame film digitizer at your disposal.

With a spare Super 8mm projector and a Raspberry Pi sitting around, [Joe Herman] figured he had the makings of a good way to preserve his grandfather’s old films. The secret of high-quality film transfers is a frame-by-frame capture, so [Joe] set about a thorough gutting of the projector. The original motor was scrapped in favor of one with better speed control, a magnet and reed switch were added to the driveshaft to synchronize exposures with each frame, and the optics were reversed with the Pi’s camera mounted internally and the LED light source on the outside. To deal with the high dynamic range of the source material, [Joe] wrote Python scripts to capture each frame at multiple exposures and combine the images with OpenCV. Everything is stitched together later with FFmpeg, and the results are pretty stunning if the video below is any indication.

We saw a similar frame-by-frame grabber build a few years ago, but [Joe]’s setup is nicely integrated into the old projector, and really seems to be doing the job — half a million frames of family history and counting.

[via Geek.com]

The Many Faces of JTAG

Wouldn’t it be great if there were just one standard for attaching to, programming, and debugging hardware?  If you could just plug in and everything would just work? Dream on, dreamer! But of course we hobbyists aren’t the only people to suffer from multiple standards. Industry has the same problems, writ large. In response to the proliferation of smart devices — microcontrollers, sensors, and their friends — on any given PCB makes it difficult to test them all, much less their function as a system.

The Joint Test Action Group (JTAG) got together in the mid-80s to make automated testing of circuit boards a standardized process. A JTAG port can be found on almost any piece of consumer electronics with enough brains to warrant it, and it’s also a tremendously useful entry point for debugging your own work and hacking into other’s. You’re going to need to use JTAG someday.

Implemented right, it’s a very cool system that lets you test any compliant IC on the board all from a single connector. It’s mostly used by hackers for its ability to run and halt individual processors, and put them in debugging modes, inspecting their memory states, etc. Essentially every microcontroller responds to JTAG commands, and it’s an incredibly widespread and powerful standard. A victory for rationality and standardization!

The connector pinout was, of course, left up to the manufacturer. The horror!

Five Signals

In principle, JTAG uses five signal lines. They form a chain starting at the debugger, where one device’s output is the next device’s input, until the result is returned back to the debugger.

654px-jtag_chainJTAG, as imagined by Vindicator CC BY 2.5

  • Test Data In (TDI) is the input from the debugger
  • Test Data Out (TDO) is the return end of the chain
  • Test Clock (TCK) clocks this data along synchronously, similarly to SPI
  • Test Mode Select (TMS) lets the devices know that they’re being debugged — it’s a global chip select
  • Test Reset (TRST) is an optional signal that resets all devices in the chain

There are other signals as well, but they’re not standard and are mostly individual device resets. If you’re programming ARM chips, you’ll probably also encounter Serial Wire Debug (SWD) which is a two-wire simplification of JTAG where the TMS line is used for bidirectional data transfer (SWDIO) and the clock clocks (SWDCLK).

One Thousand Configurations

With only five signals, or a two-signal subset of these, you’d think that there were a limited number of possible pinouts. That would be naïve. You will commonly be presented with twenty-pin, fourteen-pin, and ten-pin versions of JTAG ports. Naturally, there are sub-varieties within each pin-count. Here’s a taxonomy of the ones that I’ve encountered. There must be others.

The madness started with ARM, when they decided to carry five signals on a twenty-pin connector. (To be fair, they added a few extra signal lines, and many redundant grounds.) This is also the only twenty-pin connector that I’ve seen, and it’s a good bet to start out with this pinout if you see two rows of ten pins. The two MIPS JTAG versions can also come in twenty-pin housings, but since they only use fourteen of them, they also appear in fourteen-pin versions.

Which brings us to the first level of JTAG hell: fourteen pins. In addition to the ARM-14 pinout and the aforementioned MIPS variants, there’s also Xilinx and TI’s MSP430 JTAG layout in fourteen pins. Boo! There’s going to be some trial and error here. If there’s an MSP430 chip (or you’re using [Travis Goodspeed]’s GoodFET, then the TI version is most likely. If you see a Xilinx FPGA, that’s a solid bet. If it’s a router, bet on the MIPS layout first, but if there’s an ARM chip prominently in play you might want to try ARM-14.

Which brings us into the pit of despair: the ten-pin headers. The good news here is the Alterra ByteBlaster and AVR pinouts match, and are maybe the most common layout of all. When I see a ten-pin header, I start here. Unfortunately, Freescale/Lattice semiconductor also has its own ten-pin JTAG, and it’s different, so that’s your next port of call.

Even that’s no guarantee though: my Lattice FRDM-KL25Z dev board has both ten-pin JTAG and SWD ports, where neither of the two correspond to any JTAG layout that I know, but at least they’re described in the datasheet. All of the other minor JTAG variants seem to be ten pins as well, so if you find a ten-pin header that’s not Alterra or Lattice, you’re in the deep end of the pool.

Which One Is It?

All of these connectors are, of course, symmetric. Once you’ve got a pin count and some good guesses, test them out. You should be able to figure out the grounded pins very easily with a continuity tester. Does it match any of the standards? If yes, you can figure out the orientation, and you’re on your way. If you know the chip manufacturer, start off with their JTAG version first, naturally. If you can trace known JTAG lines out from the IC, do so.

But then there are times when the connector is entirely non-standard, either because they designers don’t want you using it or they use a custom testing jig and don’t care. In these cases, it’s time to start playing the brute-force lottery. Take a wild guess at which pins are which, and see if you get a response. Repeat. And repeat. And repeat.

jtagulator_imageBut if you’re a hacker, the words “brute force” make you instantly think “automation”, right? Among other devices, [Joe Grand]’s JTAGulator might be able to work out the pins for you.

It works by testing the JTAG chain, and when the pins are set up right, it’ll get a response. From this, it can figure out how many chips are in the chain, because each chip is essentially a one-bit shift register. Next it will ask for each chip’s ID code. When it starts getting sensible answers, you’ve won. Read [Joe]’s slides from his DEFCON talk (PDF) on the matter if you want to learn more.

Get Physical

So far, we’ve only concerned ourselves with the signals that the JTAG pins carry. Without trying to obfuscate things, there are two choices of pin-pitch that are commonly used: the wide 0.1″ pitch and a smaller 0.05″ spacing. I’ve only ever seen ten-pin JTAG headers in the thin version, and they’re more common than the 0.1″ version. Before you even get to worry about programming the board, you’re going to need an adapter. And besides the pin-spacing issue, there’s also gender. You’re going to need more adapters.

And then there’s obfuscation. Vendors who don’t want you using their JTAG interfaces once the hardware is in the wild will disguise them in every way possible. Even getting a probe on the right copper pads can be hard work.

Building Your Own

But what about designing JTAG into your own work? Which pinout should you choose? I default to the AVR/Alterra pinout in 0.1″ spacing whenever possible. One reason is that it leaves plenty of room for routing on home-etched boards, and the other is that it’s easy to drill for headers or leave bare copper pads for pogo pins.

For a pin jig on 0.1″ spacings, I’ll just jam the pogo pins into the end of a cable connector and try to steady my hands on the table while pressing enter on my laptop with the other, all the while playing the tuba with my toes. The pins will wiggle in the slots and I’ll curse. Reasonable people will resort to programming jigs, and there’s an app for that.

If you don’t have steady hands, and can’t be bothered with a test fixture, look into Tag-Connect. Tag-Connect is a simple idea: adding registration pins (and optionally locking tabs) in a non-symmetric configuration around a 0.05″ JTAG pattern. The registration pins make it easy to hold the pogo pins in place, and the locking clips give you your hands back. Instead of populating a header on every board you produce, you just need to expose copper pads and drill a few holes. It’s a brilliant system, and it’s been picked up by TI, Microchip, and others. A DIY version of Tag-Connect in 0.1″ pitch is on my short list of programmer connectors to standardize around.

JTAG: Love It or Loathe It

Love it or loathe it, you’re going to need to use JTAG some day, whether for your own designs and standardization purposes, for programming a dev board, or hacking into some appliance. It’s surprising that something so apparently simple as connecting up five signal lines can lead to such complication. The good news is that once you’re over this first hurdle, JTAG is actually reasonably well standardized at the protocol level. But that’s a topic for another time.

Extech Power Supply: If it Ain’t Broke, Fix it Anyway

[Wolf] came into possession of an Extech power supply that wasn’t quite in working order. It has been used in battery manufacturing and was fairly corroded. He was able to fix it but found there was an issue with the power supply that wasn’t a defect. By design when you turn off the outputs, the voltmeters read zero. That means you can’t adjust the voltage to a known value without turning on the outputs. Sure, you ought to disconnect things before you adjust, but you can only hope you’ll remember.

At first, he tried to use the existing output control switch, but that really cut power. Instead, he turned to a small microcontroller board usually used for servo control. He added a few nice looking pushbuttons to the front panel. There was plenty of room in the enclosure to mount the controller board and four relays. You can see the final result in the video below.

You can guess the rest. The micro is able to read the controls, set the power supply, and switch the outputs off without killing the metering. This required some major mechanical surgery on the output terminals, by the way. In addition, the micro monitors the voltage output with an analog to digital converter and stores state when the power is dropping out. That way it can restore things on the next power event.

[Wolf] did eight videos covering each step of the process. You can find the result in the video below, but be sure to watch the ones that lead up to it as well.

The Extech supply looks nice, but we’ve noticed it is getting easier to build your own thanks to some interesting and inexpensive modules. Or you can build one in pieces if you prefer.

[Fran Blanche] Goes In-Depth with the Maillardet Automaton

We’re not specialists, but the Maillardet Automaton is one of the more amazing mechanical machines that we’ve seen in a while, and [Fran Blanche] got to spend some time with it in an attempt to figure out how it’s mysterious missing pen apparatus would have worked. The resulting video, embedded below, is partially her narrative about the experiment she’s running, and part straight-up mechanical marvel.

If you need a refresher course on Maillardet’s Automaton, we’ll send you first to Wikipedia, and then off to watch this other video , which has a few great close-ups of the cams that drive everything.

floating-stylus-test-for-the-maillardet-automaton-with-commentary-yuw30scp_98mkv-shot0001And then come back to [Fran]’s video. Many parts of the machine, including the pen and his clothes, are missing. Because the machine’s hand moves in three dimensions, pressing down on the pen harder in the downstroke than on the upstroke, the pen’s construction is important for a faithful reproduction of the machine’s full abilities. [Fran] builds a weighted ball-point pen design to test out her theory that the missing pen was essentially a spring valve that feeds more ink when pressed down further.

Besides hearing [Fran] work through the experiment, you also get to watch this enchanting machine do its thing for ten minutes, and that alone is worth your time. If you want more Maillardet Automaton goodness, check out our previous coverage of [Fran]’s work on the machine or her blog coverage thereof. Or lighten up a bit with this whimsical “robot” café.

Measuring Spurious Emissions of Cheap Handheld Transceivers

If you buy an amateur transceiver cheap enough to make a reasonable grab bag gift or stocking stuffer, you get what you pay for. And if this extensive analysis of cheap radios is any indication, you get a little more than you pay for in the spurious emissions department.

Amateur radio in the United States is regulated by the FCC’s Part 97 rules with special attention given to transmitter technical specifications in Subpart D. Spurious emissions need to be well below the mean power of the fundamental frequency of the transmitter, and [Megas3300] suspected that the readily available Baofeng UV-5RA dual-band transceiver was a little off spec. He put the $20 radio through a battery of tests using equipment that easily cost two orders of magnitude more than the test subject. Power output was verified with a wattmeter, proper attenuators were selected, and the output signal scanned with a spectrum analyzer. Careful measurements showed that some or all of the Baofeng’s harmonics were well above the FCC limits. [Megas3300] tested a few other radios that turned out to be mostly compliant, but however it all turned out, the test procedure is well documented and informative, and well worth a look.

The intended market for these radios is more the unlicensed crowd than the compliant ham, so it’s not surprising that they’d be out of spec. A ham might want to bring these rigs back into compliance with a low pass filter, for which purpose the RF Biscuit might prove useful.

[via r/AmateurRadio]

Real-Time Planet Tracker With Laser-Point Accuracy

Space. The final frontier. Unfortunately, the vast majority of us are planet-locked until further notice. If you are dedicated hobbyist astronomer, you probably already have the rough positions of the planets memorized. But what if you want to know them exactly from the comfort of your room and educate yourself at the same time? [Shubham Paul] has gone the extra parsec to build a Real-Time Planet Tracker that calculates their locations using Kepler’s Laws with exacting precision.

An Arduino Mega provides the brains, while 3.5-turn-pan and 180-degree-tilt servos are the brawn. A potentiometer and switch allow for for planet and mode selection, while a GPS module and an optional MPU9250 gyroscope/magnetometer let it know where you are. Finally a laser pointer shows the planet’s location in a closed room. And then there’s code: a lot of code.

The hardware side of things — as [Shubham Paul] clarifies — looks a little unfinished because the focus of the project is the software with the intent to instruct. They have included all the code they wrote for the RTPT, providing a breakdown in each section for those who are looking to build their own.

There is an extra step to auto-align the RTPT to north, otherwise you’ll have to do so manually. But [Shubham Paul] has designed it so that even if you move the tracker about, the RTPT will readjust its calculations in real time. Each part of the project includes a wealth of related information beyond simple instructions to adequately equip any prospective builders.

This hack gets the job done. If it’s looks you’re after, an artistic expression of maker skills and astronomy can be seen in this planetary map that relies on persistence of vision.

TP-Link Debug Protocol Gives Up Keys To Kingdom

If the headline makes today’s hack sound like it was easy, rest assured that it wasn’t. But if you’re interested in embedded device hacking, read on.

[Andres] wanted to install a custom OS firmware on a cheap home router, so he bought a router known to be reflashable only to find that the newer version of the firmware made that difficult. We’ve all been there. But instead of throwing the device in the closet, [Andres] beat it into submission, discovering a bug in the firmware, exploiting it, and writing it up for the manufacturer.  (And just as we’re going to press: posting the code for the downgrade exploit here.)

This is not a weekend hack — this took a professional many hours of serious labor. But it was made a lot easier because TP-Link left a debugging protocol active, listening on the LAN interface, and not requiring authentication. [Andres] found most of the information he needed in patents, and soon had debugging insight into the running device.

After some heavy-duty static reverse engineering based on the firmware that he downloaded from the manufacturer’s website, he found a buffer overflow opportunity in the code, and managed to run his own code over the debugging link.

Because [Andres] is a security professional, he gets paid for finding vulnerabilities like this, but also for making them sound ominous. Still, he notes that you can only reach the debug protocol over the local LAN, and not from the network at large. So it’s much more likely that you’ll use this exploit to flash the firmware of your choice than it is that any baddies would do so. (It’s not a bug, it’s a feature!) But still, this is an awesome hack!

Thanks to [norber] for the tip!

Jumper Cables Block Trains

Standing Rock, North Dakota has been the site of a major protest this year against the Dakota Access Pipeline project. Protesters have sought to delay the pipeline’s progress by a wide variety of means, and both sides in the conflict have been accused of a variety of misdeeds.

An anonymous group supporting the protesters has released a video describing how they stop trains without the use of physical barricades. The video begins with police removing automobiles used to block the tracks and escorting trains through level crossings, showing how these traditional methods have been ineffective.

The video then goes on to outline what is described as a “sneaky” way of halting trains. Most railroads use what is known as a track circuit — a current run through the rails of the track detects when a train passes over it by the axles completing an electrical circuit between the two. By using a standard automotive jumper cable to connect the two rails together instead, the circuit is completed and falsely indicates to the railway signalling system that a train is present on the track in question. Due to the safety-critical nature of the railway, no trains can be run on the track until the short circuit is removed, else there is a great risk of collisions between trains on the network.

Intended as a practical guide, strategies to maximize disruption are outlined, such as hiding the cables under snow and painting them in black to evade detection as long as possible. Instructions on how to best make a solid connection to the rails are also shared.

It goes without saying that interfering with major infrastructure is risky, dangerous, and highly illegal. Protesters have already been arrested for physically blocking trains. Perpetrators of this method will surely be arrested if caught, and circumventing the technology could easily result in harsher charges associated with electronic security and safety systems. This is sabotage (deliberately obstructing) and undermines the validity of peaceful protest.

This shows how ingenuity is often spawned by turmoil and frustration. Reflect on human nature, and catch the video below the break.

Hybrid Raspberry Pi + PIC32 = Oscilliscope and Function Generator

The PicBerry is a student final project by [Advitya], [Jeff], and [Danna] that takes a hybrid approach to creating a portable (and affordable) combination digital oscilloscope and function generator. It’s based on the Raspberry Pi, features an intuitive Python GUI, and can generate and measure simultaneously.

But wait! The Raspberry Pi is a capable little Linux machine, but meeting real-time deadlines isn’t its strong suit. That’s where the hybrid approach comes in. The Pi takes care of the user interface and other goodies, and a PIC32 over SPI is used for 1 MHz sampling and running a DAC at 500 kHz. The idea of combining them into PicBerry is to get the best of both worlds, with the Pi and PIC32 each doing what they are best at. The readings are sent in batches from the PIC32 to the Pi, where the plot is updated every 30 ms so that user does not perceive any visible lag.

The project documentation notes that improvements can be made, the speeds are a far cry from regular bench equipment, and the software lacks some typical features such as triggering, but overall not bad at all for under $50 of parts. In fact, there are hardly any components at all beyond the Raspberry Pi, the PIC32, and a MCP4822 digital-to-analog converter. A short demo video is embedded below.

Thanks to [Bruce Land] — who in the past created a zero CPU cycle function generator — for giving us a heads up!

Make Your Own Arduino Header Pins

There are two kinds of people in the world (and, no, this isn’t a binary joke). People who love the Arduino, and people who hate it. If you’ve ever tried to use a standard prototype board to mount on an Arduino, you’ll know what kind of person you are. When you notice the pins aren’t on 0.1 inch centers, you might think, “What the heck were those idiots thinking!” Or, you might say, “How clever! This way the connectors are keyed to prevent mistakes.” From your choice of statement, we can deduce your feelings on the subject.

[Rssalnero] clearly said something different. We weren’t there, but we suspect it was: “Gee. I should 3D print a jig to bend headers to fit.” Actually, he apparently tried to do it by hand (we’ve tried it, too). The results are not usually very good.

He created two simple 3D printed jigs that let you bend an 8-pin header. The first jig bends the correct offset and the second helps you straighten out the ends again. You can see the result in the picture above.

[Rssalnero] notes that the second jig needed reinforcement, so it is made to take 8 pins to use as fulcrums. Probably doesn’t hurt to print the jigs fairly solid and using harder plastic like ABS or PETG, too. Even if you don’t have a 3D printer, this is about a 15 or 30 minute print on any sort of reasonable printer, so make a friend. Worst case, you could have one of the 3D printing vendors make it for you, or buy local.

We love little tool hacks like this. If you are too lazy to snap 8 pins off a 40 pin strip, maybe you’d like some help. If you’d rather go with a custom PC board, you might start here.

All I Want for Christmas is a 4-Factor Biometric Lock Box

It’s the most wonderful time of the year! No, we’re not talking about the holiday season, although that certainly has its merits. What we mean is that it’s time for the final projects from [Bruce Land]’s ECE4760 class. With the giving spirit and their mothers in mind, [Adarsh], [Timon], and [Cameron] made a programmable lock box with four-factor authentication. That’s three factors more secure than your average Las Vegas hotel room safe, and with a display to boot.

Getting into this box starts with a four-digit code on a number pad. If it’s incorrect, the display will say so. Put in the right code and the system will wait four seconds for the next step, which involves three potentiometers. These are tuned to the correct value with a leeway of +/- 30. After another four-second wait, it’s on to the piezo-based knock detector, which listens for the right pattern. Finally, a fingerprint scanner makes sure that anyone who wants into this box had better plan ahead.

This project is based on Microchip’s PIC32-based Microstick II, which [Professor Land] starting teaching in 2015. It also uses an Arduino Uno to handle the fingerprint scanner. The team has marketability in mind for this project, and in the video after the break, they walk through the factory settings and user customization.

We have seen many ways to secure a lock box. How about a laser-cut combination safe or a box with a matching NFC ring?

Bitbanging Qualcomm Charge Controllers

With more and more manufacturers moving to USB-C, it seems as though the trusty USB port is getting more and more entrenched. Not that that’s a bad thing, either; having a universal standard like this is great for simplicity and interconnectability. However, if you’re still stuck with USB 2.0 ports on your now completely obsolete one-year-old phone, there’s still some hope that you can at least get rapid charging. [hugatry] was able to manipulate Qualcomm’s rapid charging protocol to enable it to work with any device.

The protocol in question is supposed to work only on supported devices. Namely, anything with a Qualcomm Snapdragon or other similar products. [hugatry] had a Qualcomm rapid charging-capable USB port, but no supported devices. What he found out after some investigation, though, was that it’s extremely easy to bitbang the protocol to request essentially any amount of power from the Qualcomm device. He didn’t even need a microcontroller to do the handshaking, only passive components.

It’s a little surprising that getting around a proprietary standard in this day in age is so straightforward (and he does note that while it worked for him, your mileage may vary), but we’re happy to see it nonetheless. [hugatry]’s process is definitely worth checking out, as is his video which you can find after the break.

Set Your Clocks to Decimal Time

Many stop lights at street intersections display a countdown of the remaining seconds before the light changes. If you’re like me, you count this time in your head and then check how in sync you are. But did you know that if the French had their way back in the 1890s when they tried to introduce decimal time, you’d be counting to a different beat? Did you know the Chinese have used decimal time for millennia? And did you know that you may have unknowingly used it already if you’ve programmed in Linux? Read on to see what decimal time is along with the answers to these questions.

How We Got Where We Are

Babylonian numeralsBabylonian numerals, By Jose117 [CC BY-SA 4.0], via Wikimedia CommonsFirst off, just why do we have 60 seconds, 60 minutes and 24 hours in a day? The 24 hour day started with the Egyptians breaking the number of daylight hours into 12. One possible reason for using 12 is that it’s the number of segments we have separated by knuckles on the four fingers of each hand. Notice how easily you can count them using your thumbs, something you should be comfortable with in these days of thumb-manipulated mobile phones.

The use of 60 minutes in an hour and 60 seconds in a minute didn’t come into everyday use until the invention of mechanical clocks in the 16th century. Prior to that their use just wasn’t practical. The selection of 60 for the divisions stems ultimately from the Sumerians with their sexagesimal (base 60) number system, though it’s difficult to find just when they were chosen for the units of time. The words minute and second come from the latin pars minuta prima, which means “first small part”, and pars minuta secunda, or “second small part”.

The second was for a long time defined to be 1/86400 of a mean solar day (60*60*24 = 86400). It was recently defined more precisely as “the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium 133 atom”.

But as you can see above, though necessary and useful, all our units were derived from fairly arbitrary sources and are of arbitrarily selected lengths.

Metric Time Vs Decimal Time

Before getting into decimal time, we should clear up what we mean by metric time, since the two are often used incorrectly. Metric time is for measurement of time intervals. We’re all familiar with these and use them frequently: milliseconds, microseconds, nanoseconds, and so on. While the base unit, the second, has its origin in the Sumerian base 60 number system, it is a metric unit.

Decimal time refers to the time of day. This is the division of time using base 10 instead of dividing the day into 60, 60 and 24.

French Decimal Time

French decimal time clockFrench decimal time clock, By Cormullion, Own work [CC BY-SA 3.0], via Wikimedia CommonsThere were a few attempts in France to switch to decimal time. The first began use in 1794 during the French Revolution (1789-1799). They divided the day into 10 hours, each hour being 100 minutes long, and each minute containing 100 seconds.

This allowed for time to be written as we would, 2:34 for 2 hours and 34 minutes, but also as the decimal numbers 2.34 or even 234. For timestamping purposes we’d write 2016-12-08.234. We could also write it as the fraction 0.234 of the day or written as a percentage, 23.4% of the day. The seconds can simply be added on as an additional 2 digits.

That’s certainly simpler than what we currently have to do with our standard system. To convert 2:34 AM to a single number representing the duration of the day in minutes we have to do:

(2 hours*60 min/hour)+34 min=154 minutes

As a fraction of the day it’s:

154 min/(60 min/hour * 24 hours)=0.1069

And finally, 0.1069 as a percentage is 10.69%. Summarizing, that’s the time 2:34 AM represented as 154 minutes, 0.1069, and 10.69%. You can hardly blame the French for trying. Vive la revolution!

Decimal time went into official use in France on September 22, 1794 but mandatory use ended April 7, 1795, giving it a very short life. Further attempts were made in the late 1800s but all failed.

Swatch Beat watchSwatch Beat watch

If you do the math, each hour in the French decimal system was 144 conventional minutes long, each minute was 86.4 conventional seconds and each second was 0.864 conventional seconds. If you can get used to an hour that’s twice as long, probably not too difficult a feat, the minutes and seconds are reasonably close to what we’re used to. However, science uses the second as the base of time and that’s a huge amount of momentum to overcome.

Incidentally, in 1998, as part of a marketing campaign, the Swatch corporation, a Swiss maker of watches, borrowed from the French decimal time by breaking the day into 1000 ‘.beats’. Each .beat is of course 86.4 seconds long. For many years they manufactured watches that displayed both standard time and .beat time, which they also called Internet Time.

Chinese Decimal Time

China has as long and varied a history as that of the West, and for over 2000 years, China used decimal time for at least one unit of its time system. They had a system where the day was divided into 12 double hours, but also a system dividing it into 100 ke. Each ke was further divided into either 60 or 100 fen at different times in its history.

Fractional Days

But decimal time is in use today. The fractional day is also a form of decimal time and is used in science and in computers. The time of day is expressed as the conventional 24 hour time but converted to a fraction of the day. For example, if time 0 is 12:00 midnight, 2:30 AM is:

((2*3600 sec/hour) + 30*60 sec/min) / 86400 sec/day = 0.10417

As many decimal places as needed can be used.

One example where fractional days are used is by astronomers for Julian days. Julian days are solar days in decimal form with 0 being noon Universal time (UT) at the beginning of the Julian calender, November 24, 4717 BC. For example, 00:30:00 UT January 1, 2013 as a Julian date is 2,456,293.520833.

Microsoft Excel also uses fractional days within dates similar to Julian dates but called serial dates. The time of day is stored as a decimal fraction of the 24 hours clock starting from midnight.

Unix/Linux Time

We may be repulsed by the idea of switching to an unfamiliar decimal time in our daily lives but many of us have used it when calling the time() function in Unix variations such as Linux. This function returns the current time in seconds since the beginning of some epoch. The Unix epoch began on 0:00:00 UTC January 1, 1970, a Thursday. But at least those seconds are of the length we’re used to — no need to resynchronize our internal counter there.

Vive La Revolution!

But while the French revolution is in the past, rebels do exist here at Hackaday. [Knivd] is one such who has devised a decimal time called C10 that’s slightly different from the French’s. And he already has at least one fellow conspirator, [Danjovic], who’s already made a decimal clock called DC-10. How long before we’re all counting to the beat of a different drum, and crossing those intersections before the light has changed?

A Beautiful Morse Key From A Hard Drive Actuator

Morse code, or CW, is a subject that divides the amateur radio community from top to bottom. For some it’s a faded anachronism, while for others it’s the purest form of the art. With it no longer in significant commercial or military use it is radio amateurs who keep it alive, and those for whom it is a passion devote considerable effort to its continuing use.

With well over a century of history behind it there are a huge array of morse keys available to the CW enthusiast. From vintage telegraph keys through WW2 surplus military keys to sideways “bug” keys and modern boutique handcrafted keys, many operators will amass a collection for the love of it, and regularly use them all.

Just one of the hand-drawn illustrations for this project.Just one of the hand-drawn illustrations for this project.

Other operators create their own keys, either crafting them from raw materials or using whatever materials they have at hand. Keys have been made from every conceivable piece of junk that will conduct electricity, and made contacts to all parts of the world.

[H. P. Friedrichs, AC7ZL] has produced such a home-made key from surplus material, but it has nothing of the junkbox about it. He’s used the head actuator from a surplus hard drive as the arm of a straight key, and the result is an item of beauty.  The actuator bearing is the pivot point, and the business end of the key replaces the hard drive’s heads. The spring is provided by the repulsive force between magnets, the connection at the rear is provided by a piece of guitar string, and the contacts themselves are taken from a surplus power relay. Even his write-up is a thing of beauty, a compelling read with hand-drawn illustrations. If you are not a Morse enthusiast it’s still an engaging project.

We’ve featured many keys here over the years, and this isn’t the first one using a hard drive actuator, as this mint tin paddle shows. Among others we’ve linked you to a collection of unorthodox keys, and of course shown you a vintage telegraph key with a Raspberry Pi decoder.

Amiga Zorro HDMI Graphics Card Hits The Market

If you were a computer enthusiast in the late 1980s or early 1990s, the chances are that one of your objects of desire would have been a Commodore Amiga. These machines based on the 68000 line of processors and a series of specialized co-processors offered the best compromise between performance and affordability at the time, with multitasking, a GUI, and graphics capabilities that were streets ahead of their competition.

The Amiga story is littered with tales of what might have been, as dismal marketing and lacklustre product refreshes caused it to lurch from owner to owner and eventually fade away from the mainstream in the mid 1990s. But it’s been one of those products that never really died, as a band of enthusiasts have kept a small market for its software and hardware alive.

Workbench as you may not have seen it before.Workbench as you may not have seen it before.

Earlier this year we showed you a prototype of an unusual graphics card, a modern GPU implemented on an FPGA board that brought up-to-date HDMI monitor support to the Zorro expansion slots found in the big-box Amigas. It’s thus very interesting today to find that the board made it to market, and that you can buy one for your Amiga if you have a spare 189 Euros (now sold out but taking pre-orders for another production run). Producing any niche electronic product is a significant challenge, so it is always positive to see one that makes it.

As well as HDMI output the board features a micro SD card slot that is mountable as an Amiga volume, and an expansion header that is toured as “Hacker friendly”. Best of all though, the whole board is open-source with all resources on a GitHub repository, so as well as reading our coverage of the prototype you can immerse yourself in its internals if that is your thing.

It’s always good to see a new piece of hardware for an old computer see the light of day, though it’s fair to say this development won’t revive the Amiga platform in the way that the Raspberry Pi has for RiscOS. Still, the mere fact of an open-source Zorro FPGA implementation being released should mean that other cards become possible, so we await developments with interest.

[via forums.xilinx.com]

The 3D-Printed Mutoscope You’ve Always Wanted

[John] got his hands on a 3D printer, and did what any hacker with a new toy would, printed himself a Mutoscope. (A what?) A Mutoscope is an early flip-book based motion picture machine, and in this case it displays 24 frames from “A Clockwork Orange”. [John]’s 3D-printed machine is, not coincidentally we assume, printed in orange plastic.

The model for the frame is up on Thingiverse, but there’s not all that much to it, honestly. It’s a frame and a few wheels that hold some skewers in place. The rest of the work is making the flaps.

But getting to the end product wasn’t a straight walk. [John] describes all of the starts and stops in his blog, aptly named “Fail Try Again”. We like seeing the whole process rather than just the final, seventh, iteration of the device.

Where to take this project next? We want to see a design with a mounting bracket for a cheap stepper motor built in. We’ve always wanted our own custom signage, and there’s nothing cooler than the flap-flap-flap noise that flip book pages make when being switched. We must not be alone in thinking so, because we’ve seen two beautiful DIY builds in the last two years: this one done in multiples for advertising purposes and this one done just for the lulz. [John]’s project is a lot simpler, and thus a lot more accessible. We hope it inspires a few of you to make your own.

Animatronic Head Responds with Animated GIFs

[Abhishek] describes Peeqo as a “personal desktop robotic assistant” that looks like “the love child of an Amazon Echo and a Disney character.” We’re not sure about that last part — we’re pretty sure [Bender Bending Rodriquez] would fail a paternity suit on this one. Just look at that resemblance.

vkwnaidWhatever Peeqo’s parentage may be, it’s a pretty awesome build, and from the look of [Abhishek]’s design notes, he put a lot of thought into it, and a lot of work too. The build log reveals 3D-printed parts galore, custom-etched PC boards, and a hacked Raspberry Pi to both listen for voice commands and play responses in the form of animated GIFs on Peeqo’s ‘face’. The base has six modified RC servos to run the Gough-Stewart platform that lets Peeqo emote, and the head contains pretty much all the electronics. Beyond the hardware, a ton of programming went into giving Peeqo the ability to communicate through head gestures and GIFs that make sense for the required response.

Whether it’s bopping along to the tunes on your playlist or motivating you to lay off the social media with [Will Ferrell]’s flaming angry eyes, Peeqo looks like a ton of fun to build and use. Conveniently enough, [Abhishek] has shared all his files so you can build one too.

We haven’t seen anything like Peeqo before, but we have seen a lot of Amazon Echo hacks and even a few Stewart platform builds. But did we inadvertently feature a project starring Peeqo’s dad way back in 2009?

[Thanks to Aaron Cofield for the tip]

Speed Run [James Bruton’s] Star Wars Builds

We’ve been following [James Bruton]’s builds here on Hackaday for quite a while and he has built some impressive stuff. We love how he often doesn’t cover everything up, leaving enough room to admire the working bits under the hood. Just in time for the release of the new Star Wars movie, Rogue One, [James] put together an overview of his Star Wars robot builds.

The build summary includes his R6 droid, his GNK walking droid and the third revision of his BB-8 droid. [James Bruton]’s videos have tons of detail in them over many, many parts (for example, his BB-8 R3 playlist is 15 parts and his Ultron build currently has 26 episodes and counting!)

There’s a quick overview of each of the three robot builds in this video, and it includes links to the playlists for each build for those who want more detail. This is just what you need to glimpse all of the clever design that went into these wonderfully crafted droids. And if you haven’t seen it yet, you should check out his series elastic actuators that he’s working on for the Ultron build, they give a robot some relief from rigidity.

Thermoelectric Paint Opens Prospect Of Easier Energy Harvesting

We will all be used to the thermoelectric effect in our electronic devices. The property of a junction of dissimilar conductors to either generate electricity from a difference in temperature (the Seebeck effect), or heating or cooling the junction (the Peltier effect). Every time we use a thermocouple or one of those mini beer fridges, we’re taking advantage of it.

Practical commercial thermoelectric arrays take the form of a grid of semiconductor junctions wired in series, with a cold side and a hot side. For a Peltier array the cold side drops in temperature and the hot side rises in response to applied electric current, while for a Seebeck array a current is generated in response to temperature difference between the two sides. They have several disadvantages though; they are not cheap, they are of a limited size, they can only be attached to flat surfaces, and they are only as good as their thermal bond can be made.

Researchers in Korea have produced an interesting development in this field that may offer significant improvements over the modules, they have published a paper describing a thermoelectric compound which can be painted on to a surface. The paint contains particles of bismuth telluride (Bi2Te3), and an energy density of up to 4mW per square centimetre is claimed.

This all sounds impressive, however as always there is a snag. The coating is painted on, but then it must be sintered at high temperature to form the final material. Then since the thermoelectric Seebeck effect voltage generated across a junction is tiny, some means must be arrived at to connect multiple regions of paint in series to achieve a usable voltage. The paint is produced in both n- and p-type semiconductor variants, so they appear to achieve this series connection by alternating bands of each. And finally the efficiency of the whole is only as good as the ability of its cold side to lose heat, so we are guessing to be effective it would require something extra to improve heat transfer away from it. Still, it will have a thermal bond with its substrate that is second to none and it has the potential to cover the entire surface of a hot item, so it shows considerable promise. The researchers discuss using it for power generation, but  we wonder whether there is also a prospect of it being used as a Peltier effect device to provide enhanced cooling.

We’ve covered many conventional thermoelectric generators in the past. The smallest was probably this LED ring, but we’ve also shown you a thermoelectric charger for use in rural Mongolia, and this very neat candle-powered fan.

Thanks to [Jack Laidlaw].

A Handy Tutorial For Voice-Command Awesomeness

When somebody can’t find a guide on how to accomplish a particular task, we here at Hackaday admire those individuals who take it upon themselves to write one for the benefit of others. Instructables user [PatrickD126] couldn’t find a write-up on how to connect Amazon’s Alexa service, and Echo to his Raspberry Pi home security system, so his handy tutorial should get you up to speed for your own projects.

[PatrickD126] shows how loading some software onto the Raspberry Pi is readily accomplished along with enabling Alexa to communicate more directly with the Pi. From there, it’s a matter of configuring your Amazon Web Services account with your preferred voice commands, as well as which GPIO pins you’d like to access. Done! [PatrickD126] notes that the instructions in the guide only result in a temporary solution, but suggests alternatives that would allow your project to operate long-term.

For more advanced users this tutorial is probably rote, but it could save time in a crunch or hackathon scenario. Now all you have to do is connect this project to a typewriter that will allow you to dictate your next report — old school style.

[Thanks for the submission, Patrick D!]

Nylon Fibre Artificial Muscles — Powered by Lasers!

If only we had affordable artificial muscles, we might see rapid advances in prosthetic limbs, robots, exo-skeletons, implants, and more. With cost being one of the major barriers — in addition to replicating the marvel of our musculature that many of us take for granted — a workable solution seems a way off. A team of researchers at MIT present a potential answer to these problems by showing nylon fibres can be used as synthetic muscles.

Some polymer fibre materials have the curious property of increasing in  diameter while decreasing in length when heated. Taking advantage of this, the team at MIT were able to sculpt nylon fibre and — using a number of heat sources, namely lasers — could direct it to bend in a specific direction. More complex movement requires an array of heat sources which isn’t practical — yet — but seeing a nylon fibre dance tickles the imagination.

There are numerous other challenges to tackle — namely wear — on the path to creating artificial muscles, so each research vector is worthy of due consideration. For further reading, our own Moritz Walter recently outlined a number of different options for artificial muscles.

[via Gizmodo]

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