Hackaday Links: December 27th, 2015

PCBs can be art – we’ve known this for a while, but we’re still constantly impressed with what people can do with layers of copper, fiberglass, soldermask, and silkscreen. [Sandy Noble] is taking this idea one step further. He took C64, Spectrum, and Sinclair PCBs and turned them into art. The results are incredible. These PCBs were reverse engineered, traced, and eventually turned into massive screen prints. They look awesome, and they’re available on Etsy.

$100k to bring down drones. That’s the tagline of the MITRE Challenge, although it’s really being sold as, “safe interdiction of small UAS that pose a safety or security threat in urban areas”. You can buy a slingshot for $20…

[styropyro] mas made a name for himself on Youtube for playing with very dangerous lasers and not burning his parent’s house down. Star Wars is out, and that means it’s time to build a handheld 7W laser. It’s powered by two 18650 cells, and is responsible for more than a few scorch marks on the walls of [styropyro]’s garage.

Everybody is trying to figure out how to put Ethernet and a USB hub on the Pi Zero. This means a lot of people will be launching crowdfunding campaigns for Pi Zero add-on boards that add Ethernet and USB. The first one we’ve seen is the Cube Infinity. Here’s the thing, though: they’re using through-hole parts for their board, which means this won’t connect directly to the D+ and D- USB signals on the Pi Zero. They do have a power/battery board that may be a little more useful, but I can’t figure out how they’re doing the USB.

[Keith O] found a fascinating video on YouTube and sent it into the tips line. It’s a machine that uses a water jet on pastries. These cakes start out frozen, and come out with puzzle piece and hexagon-shaped slices. Even the solution for moving cakes around is ingenious; it uses a circular platform that rotates and translates by two toothed belts. Who would have thought the latest advancements in cutting cakes and pies would be so fascinating?

It’s time to start a tradition. In the last links post of last year, we took a look at the number of views from North Korea in 2014. Fifty-four views, and we deeply appreciate all our readers in Best Korea. This year? For 2015, we’ve logged a total of thirty-six views from the Democratic People’s Republic of Korea. That’s a precipitous drop that deserves an investigation. Pyongyang meetup anyone?

Raspberry Pi Laser Beam Profiler

[Anthony] at UCLA needed to verify the shape of a laser beam. Commercial units for this, as you would expect, are expensive. But a Raspberry Pi with a Pi Noir camera easily handles the task. Not only is the use of the Pi cool but so is the task – they are using lasers to cool molecules to study quantum effects. The Pi camera without the IR filter captures a wide bandwidth making it suitable for use with non-visible lasers. [Anthony] captures the beam along two axes and plots both curves on the LCD touchscreen. That data, based on the pictures, is also available on a host PC. All this in a super compact package with a 7″ touch screen display.

One reason I find this fascinating is I did something similar 1977 at the University of Rochester Laboratory for Laser Energetics. My project was measuring the energy cross-section of a laser beam. The research goal of the Laboratory was the study of inertial confinement laser fusion. While [Anthony] uses an entire camera my project was limited to a 1 dimensional array of charge coupled devices (CCD). The output went to a Tektronix storage terminal and was printed on thermal paper for reference. He uses Python running on the target system. My work used a Z80 development system the size of a tower PC to write my program in assembly language which was then executed on a single board computer. We’ve come a long way. My code is long gone but you can get [Anthony’s] on GitHub.

Raspberry Pi Communication Via LASER

[Nick Touran] wanted to make two Raspberry Pi’s communicate wirelessly. There are lots of options, but [Nick] used a LASER and a photoresistor, along with Morse code. If you don’t find Morse code fancy enough, you could always refer to it as OOK (on/off keying). The circuit uses a common LASER module and an ordinary photoresistor that varies in resistance based on light. A resistor forms a voltage divider with the photoresistor and an external A/D reads the resulting voltage.

The circuit works, but we couldn’t help but notice a few items. Not all photoresistors are as sensitive to the same light wavelengths, so for the maximum range you’d want to pick a particular photoresistor.  While the analog to digital converter is certainly workable, we couldn’t help but wonder if you couldn’t set up the divider to use the inherent threshold of the Raspberry Pi’s input pins for a simpler circuit. Of course, if you used the same technique with an Arduino, you could use the built-in A/D converter, and the A/D converter is probably easier to get working.

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Graphene Super Caps: Coming Soon?

If you read Hackaday regularly, you’ve probably heard that you can use a LASER to create graphene. There’s been a bit of research on how to make practical graphene supercapacitors using the technique (known as LIG or LASER-induced graphene). Researchers at Rice University have been working on this, and apparently they’ve had significant success inducing graphene capacitors on a Kapton substrate. The team has published a paper in Advanced Materials (which is behind a paywall) about their work.

In particular, Rice claims that they have easily produced supercapacitors with an energy density of 3.2 mW/cubic centimeter (that’s what the University’s website reports; they probably mean mW-hours/cubic centimeter) with capacitances near one millifarad per square centimeter. A key benefit of the construction method is that the capacitors continued to work after researchers bent them 10,000 times. A flexible capacitor is useful in wearable devices that would often flex, or in a device like a cell phone that could bend in your back pocket as you sit.

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Alvaro Prieto’s Laser-Shooting Robots

[Alvaro Prieto]’s talk at the Hackaday Supercon began with a slide that asks the rhetorical question “Why Laser-Shooting Robots?” Does a rhetorical question need an answer? [Alvaro] gives one anyway: “Because lasers are awesome.” We concur.

But it doesn’t hurt that DEFCON holds a laser robot contest to give you an excuse, either. You see, [Alvaro]’s laser-wielding robot was the First Place finisher in the 2014 DEFCONBOTS contest, and a much more ambitious design came in third in 2015. His Supercon talk is all about the lessons he’s learned along the way, because that’s really the point of these contests anyway, right?

“I have no idea what I’m doing.”

[Alvaro] started off with a disclaimer, but when [Alvaro] says he doesn’t know what he’s doing, what he means is that he hasn’t received formal training in building laser-wielding, autonomous turret robots. (How did we miss that class in school?)

iterations

He’s a true hacker, though; he didn’t know what he was doing when he started out but he started out anyway. [Alvaro]’s takes us from the first prototypes where he used servo motors with inadequate angular resolution mounted to balsa wood frames that he (obviously) cut with a knife by hand, through laser-cut frames with custom gearing and stepper motors, all the way to his DEFCONBOTS 2015 entry, based on OpenBeam aluminum extrusions and using professional laser-show galvos capable of swinging the beam around to thousands of points per second.

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UV Laser Projector Shines With Glow-in-the-Dark Vinyl

Mirror galvanometers were originally developed in the 17th century to precisely measure very small changes in current. Unlike other instruments of the day, a mirror galvanometer could clearly show minute current variations by translating tiny movements of the mirror into large movements of the light reflected off of the mirror. Before clean electrical amplification became possible, this was the best means of measuring tiny differences in current. True mirror galvanometers are very sensitive instruments, but hobby servos can be used as a low-fidelity alternative, like with this project on Hackaday.io created by [robives].

Using a mirror galvanometer is by far the most common technique for laser projection shows – it’s really the only way to move the laser’s beam quickly enough to create the visual illusion of a solid line in real time. A mirror galvanometer works by using coils to attract magnets attached to the mirror, allowing the angle of the mirror to change when current is applied to the coils. This movement is extremely small, but is amplified by the distance to the projection surface, meaning the laser’s beam can move huge distances in an instance. If you’ve ever seen a laser show, it almost certainly used this technique. But driving galvos requires a beefy DAC, so we can’t blame [robives] for wanting to keep it digital.

[robives’s] project side-steps the need for galvanometers by using glow-in-the-dark vinyl and a UV laser. The result is a laser beam trail which lasts much longer, which means that solid lines are visible without the need for high-speed galvos. A build like this lets you experiment with laser projections without dealing with sensitive mirror galvos, and instead use components that you probably already have sitting on your workbench.

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Laser Rangefinder Brought to Life With Arduino

Range finders are amazing tools for doing pretty much anything involving distance calculations. Want to blink some lights when people are nearby? There’s a rangefinder for that. Need to tell how far away the next peak of a mountain range is? There’s a rangefinder for that. But if you’re new to range finders and want one that’s hackable and configurable, look no further than the SF02/F rangefinder with the Arduino shield, and [Laser Developer]’s dive into what this pair can do.

Once the rangefinder and shield have been paired is when the magic really starts to happen. Using USB, the Arduino can instantly report a huge amount of raw data coming from the rangefinder. From there, [Laser Developer] shows us how to put the device into a “settings” mode which expands the capabilities of the rangefinder even more. The data can be dumped into a graph, for example, which can show trends between distance, laser strength, and many other data sets. [Laser Developer] goes one step further and demonstrates how to use this to calculate the speed of light, but from there pretty much anything else is possible as well.

And while you can just buy a rangefinder off the shelf, they are fairly limiting in their features and can cost exponentially more. This is a great start into using a tool like this, especially if you need specific data or have a unique application. But, if laser range finding isn’t for you or if this project is too expensive, maybe this $5 ultrasonic rangefinder will work better for your application.