Cloverleaf Satellite Antenna Mounted on a Pole

Tracking CubeSats For $25

June 1, 2018 by Eric Evenchick 11 Comments

CubeSats are tiny satellites which tag along as secondary payloads during launches. They have to weigh in at under 1.33 kg, and are often built at low cost. There’s even open source designs for these little spacecrafts. Over 800 CubeSats have been launched over the last few years, with many more launches scheduled in the near future.

[Thomas Cholakov] coupled a homemade cloverleaf antenna to a software-defined radio to track some of these satellites. The antenna is built out of copper-clad wire cut to the correct length to receive 437 MHz signals. Four loops are connected together and terminated to an RF connector.

This homebrew antenna is connected into a RTL-SDR dongle. The dongle picks up the beacon signals sent by the satellites and provides the data to a PC. Due to the motion of the satellites, their beacons can be easily identified by the Doppler shift of the frequency.

[Thomas] uses SDR Console to receive data from the satellites. While the demo only shows basic receiving, much more information on decoding these satellites can be found on the SDR Satellites website.

This looks like a fun weekend project, and probably the cheapest aerospace related project possible. After the break, watch the full video explaining how to build and set up the antenna and dongle.

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Tiny FPGA Board Fits In Your Laptop

May 31, 2018 by Eric Evenchick 37 Comments

There are a bunch of FPGA development boards to choose from, but how many will fit inside your laptop? The PicoEVB is a tiny board that connects to a M.2 slot and provides an evaluation platform for the Xilinx Artix-7 FPGA family.

This minimalist board sports a few LEDs, a PCIe interface, an integrated debugger, on-board EEPROM, and some external connectors for hooking up other bits and pieces. The M.2 connector provides the board with power, USB for debugging, and PCIe for user applications.

A major selling point of this board is the PCIe interface. Most FPGA boards with PCIe will cost over a grand, and will only fit in a large desktop computer. The lower priced options use older FPGAs. The PicoEVB is tiny and retails for $219. Not a bad deal when the FPGA on-board costs nearly $100.

The PicoEVB is also open source. Design files and sample projects can be found on Github.

[Thanks to Adam Hunt for the tip!]

Distorted Text Says A Lot

May 31, 2018 by Brian McEvoy 21 Comments

Getting bounced to a website by scanning a QR code is no longer an exciting feat of technology, but what if you scanned the ingredient list on your granola bar and it went to the company’s page for that specific flavor, sans the matrix code?

Bright minds at the Columbia University in the City of New York have “perturbed” ordinary font characters so the average human eye won’t pick up the changes. Even ordinary OCR won’t miss a beat when it looks at a passage with a hidden message. After all, these “perturbed” glyphs are like a perfectly legible character viewed through a drop of water. When a camera is looking for these secret messages, those minor tweaks speak volumes.

The system is diabolically simple. Each character can be distorted according to an algorithm and a second variable. Changing that second variable is like twisting a distorted lens, or a water drop but the afterimage can be decoded and the variable extracted. This kind of encoding can survive a trip to the printer, unlike a purely digital hidden message.

Hidden messages like these are not limited to passing notes, metadata can be attached to any text and extracted when necessary. Literature could include notes without taking up page space so teachers could include helpful notes and a cell phone could be like an x-ray machine to see what the teacher wants to show. For example, you could define what “crypto” actually means.

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Blowing Arcylic Canopies Using Stuff From Around The Shop

May 31, 2018 by Steven Dufresne 13 Comments

Blowing an acrylic sheet after heating it is an easy way to make a smooth and transparent canopy or bubble for anything from clams to light fixtures. [Michael Barton-Sweeney] does it using plastic blow ovens he made cheaply, mainly from stuff which most of us already have in our workshops.

All you need is a way to heat the plastic, to then clamp it down around the edges, and finally to blow air into it as you would when blowing up a balloon. Of course, there are things to watch out for such as making sure the plastic is heated evenly and letting it cool slowly afterward but he covers all that on his hackaday.io page.

He’s also on his second plastics blow oven. The first one worked very well and is perhaps the easiest to make, building up an enclosure of CMUs (cinder blocks) and brick. He had success heating it with both propane and with electric current run through Kanthal wire. But the CMUs absorbed a lot of heat, slowing down the process. So for his second one he made a cast concrete enclosure with aluminum reflectors inside to focus the heat more to where needed.

We’re not sure of everything he’s blown acrylic bubbles for but we first learned of his ovens from the transparent clams in his underwater distributed sensor network. In fact, he was inspired to do plastics blowing from a childhood memory of the Air Force museum in Dayton, Ohio, where they visited the restoration hanger and watched the restorers blowing bubbles for a B-17 ball turret.

Though if you want to go smaller and simpler for something like a light fixture then you can get away with using a toaster oven, a PVC pipe, and a toilet flange.

DIY Scrap Guitar Really Shreds

May 31, 2018 by Kristina Panos 14 Comments

[Keith Decent] recently got himself involved in a plywood challenge, and decided to make a single-pickup electric guitar. Since he is a prolific hoarder of scrap wood, the result is a lovely stack of laminates from many sources, including reclaimed cabinet doors. Really though, the wood is just the beginning—nearly every piece of this texture-rich axe started life as something else.

He’s made a cigar box guitar before, but never a bona fide solid-body electric. As you might guess, he learned quite a bit in the process. [Keith] opted for a neck-through design instead of bolting one on and using a truss rod. The face pieces are cut from his old bench top, which has a unique topology thanks to several years of paint, glue, and other character-building ingredients.

We love the geometric inlay [Keith] made for the pick guard, and the fact that he used an offcut from the process as a floating bridge. He also made his own pickup from bolts, an old folding rule, and reclaimed magnet wire from discarded wall wart transformers. Once he routed out the body and installed the electronics, [Keith] cut up an old painting he’d done on plywood to use as the back panel. Our only complaint about this beautiful guitar is that he didn’t design the back piece to be dinosaur side out. Shred past the break to give her a listen.

[Keith] wound his pickup with a little help from a drill, but a DIY pickup winder might have caused him less grief.

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The Best Part Of Waking Up Just Got Better

May 31, 2018 by Kristina Panos 23 Comments

If you ask us, one of life’s greatest pleasures is sitting down with a nice, hot cup of something of coffee, tea or hot chocolate. Of course, the best part of this ritual is when the beverage has cooled enough to reach that short window of optimal drinking temperature.

Often times the unthinkable happens—we sip too early and get burned, or else become distracted by ~~watching cat videos~~ reading our colleagues’ Hackaday posts and miss the window altogether. What’s to be done? Something we wish we’d thought of: using the beverage’s heat to cool itself by way of thermal dynamics. For [Scott Clandinin]’s entry into the 2018 Hackaday Prize, he hopes to harness enough heat energy from the beverage to power a fan that will blow across the top of the mug.

[Scott] enlisted a friend to smith a thick copper slab in a right angle formation. The gentle curve of the vertical side pulls heat from the ceramic mug and transfers it to the heat sink of a CPU cooler. Then it’s just a matter of stepping up the voltage produced by the thermoelectric generator with a boost converter. Once he’s got this dialed in, he’d like to power it with supercaps and add a temp sensor and a microcontroller to alert him that his moment of zen is imminent. We’ll drink to that!

Modular Robotics Made Easier With ROS

May 31, 2018 by Steven Dufresne 31 Comments

A robot is made up of many hardware components each of which requires its own software. Even a small robot arm with a handful of servo motors uses a servo motor library.

Add that arm to a wheeled vehicle and you have more motors. Then attach some ultrasonic sensors for collision avoidance or a camera for vision. By that point, you’ve probably split the software into multiple processes: one for the arm, another for the mobility, one for vision, and one to act as the brains interfacing somehow with all the rest. The vision may be doing object recognition, something which is computationally demanding and so you now have multiple computers.

Break all this complexity into modules and you have a use case for ROS, the Robot Operating System. As this article shows, ROS can help with designing, building, managing, and even evolving your robot.

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