Custom Strain Gauges Help Keep Paraglider Aloft

September 20, 2020 by Dan Maloney 13 Comments

No matter what they’re flying, good pilots have a “feel” for their aircraft. They know instantly when something is wrong, whether by hearing a strange sound or a feeling a telltale vibration. Developing this sixth sense is sometimes critical to the goal of keeping the number of takeoff equal to the number of landings.

The same thing goes for non-traditional aircraft, like paragliders, where the penalty for failure is just as high. Staying out of trouble aloft is the idea behind this paraglider line tension monitor designed by pilot [Andre Bandarra]. Paragliders, along with their powered cousins paramotors, look somewhat like parachutes but are actually best described as an inflatable wing. The wing maintains its shape by being pressurized by air coming through openings in the leading edge. If the pilot doesn’t maintain the correct angle of attack, the wing can depressurize and collapse, with sometimes dire results.

Luckily, most pilots eventually develop a feel for collapse, sensed through changes in the tension of the lines connecting the wing to his or her harness. [Andre]’s “Tensy” — with the obligatory “McTenseface” surname — that’s featured in the video below uses an array of strain gauges to watch to the telltale release of tension in the lines for the leading edge of the wing, sounding an audible alarm. As a bonus, Tensy captures line tension data from across the wing, which can be used to monitor the performance of both the aircraft and the pilot.

There are a lot of great design elements here, but for our money, we found the lightweight homebrew strain gauges to be the real gem of this design. This isn’t the first time [Andre] has flown onto these pages, either — his giant RC paraglider was a big hit back in January.

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Finally, A Differently Useless Machine

September 20, 2020 by Kristina Panos 32 Comments

Traditionally, the useless machine is a simple one that invites passersby to switch it on. When they do, the machine somehow, some way, turns itself off; usually with a finger or finger-like object that comes out from the box in what feels like an annoyed fashion. Honestly, that’s probably part of what drives people to turn them on over and over again.

But [Bart Blankendaal] has managed to turn the useless machine on its head. When this machine is switched to the on position, unseen forces inside the box will spin the toggle switch around 180° to the off position.

What’s really happening is that an Arduino is getting a signal from the toggle switch, and is then rotating it on a ball bearing with a stepper motor driven through an H-bridge.

It shouldn’t be too hard to make one of these yourself, given that [Bart] has provided the schematic and STLs. If we weren’t living in such touchy times, we might suggest building one of these into your Halloween candy distribution scheme somehow. Sell the switch as one that turns on a candy dispenser, and then actually dispense it after three or five tries.

Many see useless machines as tangible examples of existential quandary. Here is one that takes that sentiment a bit further by snuffing out a candle.

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Wooden Disc Player Translates Binary Back Into Text

September 18, 2020 by Kristina Panos 10 Comments

[jbumstead] used MATLAB to convert the text messages into binary to be cut out of the disk.

[jbumstead] wanted to demonstrate the idea of information-storing devices such as LPs, CDs, and old hard drives. What he came up with lies directly at the intersection of art and technology: an intricately-built machine that plays beautiful collaged wooden disks. Much like the media that inspired the Wooden Disk Player, it uses a laser to read encoded data, which in this case is short bits of text like “Don’t Panic”.

These snippets are stored in binary and read by a laser and photodiode pair that looks for holes and not-holes in the disk. The message is then sent to an Arduino Nano, which translates it into English and scrolls the text on an LED matrix. For extra fun, the Nano plays a MIDI note every time it reads a 1, and you can see the laser reading the disk through a protective acrylic shield.

Though the end result is fantastic, [jbumstead] had plenty of issues along the way which are explored in the build video after the break. We love it when people show us their mistakes, because it happens to all of us and we shouldn’t ever let it tell us to stop hacking.

If anyone knows their way around lasers, it’s [jbumstead]. We loved playing their laser harp at Supercon!

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Roll Your Own Heelys

September 17, 2020 by Kristina Panos 17 Comments

Remember Heelys, the shoes with wheels in the heels? Just lift up your toes, and away you go. We were at least ten or fifteen years older than the target demographic, but got a pair anyway just to please our inner child and have some fun. Young kids would wear them everywhere and zip around inside stores to the annoyance of everyone but other young kids. We imagine some shopkeepers got to the point where they could spot the things as they walked in the door and nipped the skating party in the bud.

[DevNerd] has conceived of the ultimate plan: if you make your own Heelys, no one necessarily has to know unless you start rolling around. [DevNerd] started by cutting some large, 20mm-deep holes in the bottoms of a pair of Air Jordans and printed a sturdy wheel and a box frame for support.

Each wheel has a bearing on both ends that spin on a threaded rod. We’re not sure why [DevNerd] went with threaded rod, because it seems like that would prematurely wear out the frame box.

Don’t want to cut up your shoes, but want some sweet roller kicks for the daily commute down the hall? You could always make them out of pallet wood.

Distance Learning Land

September 16, 2020 by Orlando Hoilett 7 Comments

[familylovermommy] has been homeschooling her kids even before the pandemic, so she’s pretty well-versed on being a learning coach and a teacher. One of the activities she designed for her boys has them creating 3D models using Tinkercad. In the spirit of openness and cultivating freethinking, she did not give them very many constraints. But rather, gave them the liberty to creatively design whatever scene they imagined.

In the Instructable, she shares her sons’ designs along with instructions to recreate the models. The designs as you’ll see are pretty extensive, so she embedded the Tinkercad designs directly into it. You can even see a number of video showcases as well.

This is a really cool showcase of some pretty stellar workmanship. Also, maybe a bit of inspiration for some of our readers who are creating work from home activities of their own.

While you’re at it, check out some of these other work-from-home hacks.

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Deep-Sleep Problems Lead To Forensic Investigation Of Troublesome Chip

September 15, 2020 by Dan Maloney 53 Comments

When you buy a chip, how can you be sure you’re getting what you paid for? After all, it’s just a black fleck of plastic with some leads sticking out of it, and a few laser-etched markings on it that attest to what lies within. All of that’s straightforward to fake, of course, and it’s pretty easy to tell if you’ve got a defective chip once you try it out in a circuit.

But what about off-brand chips? Those chips might be functionally similar, but still off-spec in some critical way. That was the case for [Kevin Darrah] which led to his forensic analysis of potentially counterfeit MCU chips. [Kevin] noticed that one of his ATMega328 projects was consuming way too much power in deep sleep mode — about two orders of magnitude too much. The first video below shows his initial investigation and characterization of the problem, including removal of the questionable chip from the dev board it was on and putting it onto a breakout board that should draw less than a microamp in deep sleep. Showing that it drew 100 μA instead sealed the deal — something was up with the chip.

[Kevin] then sent the potentially bogus chip off to a lab for a full forensic analysis, because of course there are companies that do this for a living. The second video below shows the external inspection, which revealed nothing conclusive, followed by an X-ray analysis. That revealed enough weirdness to warrant destructive testing, which showed the sorry truth — the die in the suspect unit was vastly different from the Atmel chip’s die.

It’s hard to say that this chip is a counterfeit; after all, Atmel may have some sort of contract with another foundry to produce MCUs. But it’s clearly an issue to keep in mind when buying bargain-basement chips, especially ones that test functionally almost-sorta in-spec. Caveat emptor.

Counterfeit parts are depressingly common, and are a subject we’ve touched on many times before. If you’d like to know more, start with a guide.

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The Jolly Cart-Pushing Robot

September 14, 2020 by Orlando Hoilett 4 Comments

[Lance] loves making simple robots with his laser cutter. He finds great satisfaction from watching his robots operate using fairly simple mechanisms and designs a whole slew of them inspired by different animals, including a dinosaur and a dragon. His latest build is a jolly cart-pushing robot.

He cut each piece of his robot on his laser cutter, and in order to get the pieces to fit snugly together he made each tab a little bigger than its corresponding slot, ensuring the piece wouldn’t fall out. This also helps account for the loss in the material due to kerf, which is the bit of each piece of material that gets lost in the cut end of the laser cutter.

Making his robot walk was mostly as easy as attaching each leg to a simple DC motor such that the motor would rotate each leg in succession, pushing the robot along. From time to time, [Lance] also had to grease the robot’s moving parts using a bit of wax to help reduce friction. He even used a little rubber band to give the robot some traction.

[Lance] did a pretty good job detailing the build in his video. He also linked to a few other fun little robot designs that could entertain you as well. Pretty easy hack, but we thought you might find the results as satisfying as we did.

Robot companions may be here to stay. Time will tell.

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