Twitch Stream Turned Infinity Mirror

Most Hackaday readers are likely to be familiar with the infinity mirror, a piece of home decor so awesome that Spock still has one up on the wall in 2285. The idea is simple: two parallel mirrors bounce and image back and forth, which creates a duplicate reflection that seems to recede away into infinity. A digital version of this effect can be observed if you point a webcam at the screen that’s displaying the camera’s output. The image will appear to go on forever, and the trick provided untold minutes of fun during that period in the late 1990’s where it seemed everyone had a softball-shaped camera perched on their CRT monitors.

Making use of that webcam in 2018.

While you might think you’ve already seen every possible variation of this classic visual trick, [Matt Nishi-Broach] recently wrote in to tell us about an infinity mirror effect he’s created using the popular streaming platform Twitch. The public is even invited to fiddle with the visuals through a set of commands that can be used in the chat window.

It works about how you’d expect: the stream is captured, manipulated through various filters, and then rebroadcast through Twitch. This leads to all sorts of weird visual effects, but in general gives the impression that everything is radiating from a central point in the distance.

While [Matt] acknowledges that there are probably not a lot of other people looking to setup their own Twitch feedback loops, he’s still made his Python code available for anyone who might be interested. There’s a special place in Hacker Valhalla for those who release niche software like this as open source. They’re the real MVPs.

If you’d like to get started on your infinite journey with something a bit more physical, we’ve covered traditional infinity mirror builds ranging from the simplistic to the gloriously over-engineered.

Understanding Math vs Understanding Math

One of the things hard about engineering — electrical engineering, in particular — is that you can’t really visualize what’s important. Sure, you can see a resistor and an LED in your hands, but the real stuff that we care about — electron flow, space charge, and all that — is totally abstract. If you just tinker, you might avoid a lot of the inherent math (or maths for our UK friends), but if you decide to get serious, you’ll quickly find yourself in a numerical quicksand. The problem is, there’s mechanically understanding math, and intuitively understanding math. We recently came across a simple site that tries to help with the latter that deserves a look.

If you don’t know what we mean by that, consider a simple example. You can teach a kid that 5×3 is 15. But, hopefully, a teacher at some point in your academic career pointed out to you what the meaning of it was. That if you had five packages of three items, you have 15 items total. Or that if you have a room that is five feet on one side and three feet on the other, the square footage is 15 square feet.

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Harley-Hardened Wire Helps High-Gain Antenna Hack

What does a Harley-Davidson motorcycle have to do with building antennas? Absolutely nothing, unless you happen to have one and need to work-harden copper wire to build a collinear antenna for LoRa.

We’ll explain. Never being one to settle, [Andreas Spiess] needed a better antenna for his LoRa experiments. Looking for high gain and an omnidirectional pattern, he bought a commercial colinear antenna, which is a wire with precisely spaced loops that acts like a stack of dipoles. Sadly, in a head-to-head test [Andreas] found that the commercial antenna was no better than lower gain antennas in terms of range, and so he decided to roll his own.

Copper wire is a great material for antennas since it can be easily formed without special tools and it solders like a champ. But the stuff you get at the home center is nowhere near stiff enough for a free-standing vertical whip. This is where the Harley came in: [Andreas] used his Hog to stretch out the 1.75-mm diameter (a little bigger than #14 AWG) copper wire. Not only did the work-hardening stiffen the wire, it reduced its diameter to the 1.4 mm needed for the antenna design. His vector network analyzer told him that ground-plane elements and a little fiddling with the loop diameter were needed to get the antenna to resonate at 868 MHz, but in the end it looks like the antenna is on track to deliver 5-dBi of gain.

Of course there are plenty of other ways to stretch out a wire — you could just stretch it out with hanging weights, or even with a go-kart motor-powered winch if you’re ambitious. But if you’ve got a bike like that, why not flaunt it?

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3D Printed Gun Saga: Court Case Over CAD Files Settled

Can you create 3D printed designs and distribute them freely and without restriction? Maybe, and it’s likely to become easier in the future. A settlement has been reached in the saga of the US Department of State versus Cody Wilson, and beginning August 1st the Defense Distributed library of gun designs will once again become available.

Cody is well known for creating the first 3D printed gun. He went on to found Defense Distributed, a company that published designs and technical files for 3D printing firearms before being pulled into litigation that sought to curb the distribution of such plans by subjecting them to International Traffic in Arms Regulations (ITAR) restrictions. Read that carefully, it’s the (international) distribution of CAD files at question here, and not the act of 3D printing, and Defense Distributed has been granted an ITAR exemption. Will other arms-related design files be similarly exempted? The settlement mentions upcoming rule changes seeking to make this type of exemption the standard.

As members of the Hackaday community, we’re the people to whom our friends and family turn for perspective when new technology makes it into their news feeds. Those with little or no exposure to 3D printing may easily fall to doom and gloom reports. But is this a story of doom and gloom? Absolutely not, guns are still guns and 3D printers are still 3D printers. Let’s take a look.

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Dual Brushed Motor Controller Doesn’t Care How It Receives Commands

The simple DC brushed motor is at the heart of many a robotics project. For making little toy bots that zip around the house, you can’t beat the price and simplicity of a pair of brushed motors. They’re also easy to control; you could roll your own H-bridge out of discrete transistors, or pick up one of the commonly used ICs like the L298N or L9110S.

But what if you want an all-in-one solution? Something that will deliver enough current for most applications, drive dual motors, and deal with a wide range of input voltages. Most importantly, something that will talk to any kind of input source.  For his Hackaday prize entry, [Praveen Kumar] is creating a dual brushed motor controller which can handle a multitude of input types. Whether you’re using an IR remote, a Pi communicating over I2C, an analog output or Bluetooth receiver, this driver can handle them all and will automatically select the correct input source.

The board has an ATmega328p brain, so Arduino compatibility is there for easy reprogramming if needed. The mounting holes and header locations are also positioned to allow easy stacking with a Pi, and there’s a status LED too. It’s a great module that could easily find a place in a lot of builds.

If you need even more control over your brushed motor, you can soup up its capabilities by adding a PID loop for extra smarts.

ERRF 18: The Start of Something Great

For years, the undisputed king of desktop 3D printing conferences has been the Midwest RepRap Festival (MRRF). Hosted in the tropical paradise that is Goshen, Indiana, MRRF has been running largely unopposed for the top spot since its inception. There are other conferences focused on the industrial and professional end of the 3D printing spectrum, and of course you’d find a Prusa or two popping up at more or less any hacker con; but MRRF is focused on exploring what the individual is capable of once they can manifest physical objects from molten plastic.

But on June 23rd, 2018, MRRF finally got some proper competition. As the name might indicate, the East Coast RepRap Festival (ERRF) is an event very much inspired by its Hoosier State predecessor. Held in Bel Air, Maryland, hackers on the right side of the United States for the first time had the opportunity to attended a true 3D printing festival without having to get on a plane. Not to say it was a neighborhood block party; people from all over the country, and indeed the globe, descended on the APG Federal Credit Union Arena for the two-day celebration of everything plastic.

This inaugural ERRF was, to put it mildly, a massive success. A couple of Hackaday Field Agents were in attendance, and we definitely came away impressed with the event considering it was the first attempt. We saw evidence that the RepRap dream of printable printers is still going strong, a gaggle of new printers and products that will be prying at your wallet this year, and an American-made hotend that challenges traditional wisdom. Of course we also saw a huge number of 3D printing fanatics who were eager to show off their latest creations.

We have no doubt that ERRF will return again next year, but until then, you’ll have to settle for the following collection of selected highlights from this year’s show.

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Hot Camera Contest: Build A Battery Powered Thermal Camera

Here’s a challenge for all you hardware hackers out there. Peter Jansen has opened up the Hot Camera Contest on Hackaday.io to use a thermal imaging camera in a battery-powered project.

The challenge here is simple. Use a Flir Lepton thermal imaging camera module in a battery-powered configuration. There’s a catch, though: this is a project to use the Lepton in radiometric mode, where the camera spits out an actual temperature value for each pixel. Yes, this is a documented feature in the Flir Lepton module, but so far very few people are using it, and no one has done it with a small, battery-powered device.

The rules for this challenge are to use the Flir Lepton 2.5 in radiometric mode using either the Raspberry Pi Zero W or ESP32. Any software in this challenge must spit out absolute temperature values in a text format, and there must be a demonstration of putting the Flir Lepton into low-power mode. There are two challenges here, one for the Raspi and one for the ESP32; and winner will be named for each.

Getting More from a Fascinating Sensor

The Flir Lepton is a tiny little thermal camera that’s been available to the Maker community for some time now, first through GroupGets and now through Sparkfun. For a pair of Benjamins, the specs are very impressive: the Lepton has a resolution of 60×80 pixels and everything is can be read over an SPI port. The Lepton gives any project thermal imaging, and the PureThermal board turns the Lepton into a USB device.

Peter Jansen is the creator of the Open Source Science Tricorder (yes, it’s a tricorder) which took Fourth Prize in the 2014 Hackaday Prize. You can understand how he became interested in portable, and we’re sure whatever project he has in mind for this battery-powered Flir will be awesome.

This really is a great example of what the Hackaday.io community is capable of. The goal here is to create useful Open Source drivers for some very interesting hardware, and there’s some prizes to sweeten the pot. Peter has a $125 Sparkfun gift card on offer for each of the two winners. And the challenge of solving a tricky problem and making designs easier for others is a powerful motivator. Who doesn’t like a challenge?