Underwater Drone Faces Trial By Water

December 3, 2020 by 7 Comments

Underwater Remote Operated Vehicles, or ROVs as they’re typically known, generally operate by tether. This is due to the poor propagation of radio waves underwater. [Simon] wanted to build such a drone, but elected to go for an alternative design with less strings attached, so to speak. Thus far, there have been challenges along the way. (Video, embedded below.)

The underwater drone uses a 3D printed chassis, replete with googly eyes that go a long way to anthropomorphizing the build. Four motors are used for control, with two for thrust in the horizontal plane and two mounted in the vertical plane for attitude control. This allows the drone to be set up at neutral buoyancy, and moved through the water column with thrust rather than complicated ballast mechanisms. The build aims to eschew tethers, instead using a shorter cable to link to a floating unit which uses radio to communicate with the operator on the shore.

The major struggle facing the build has been sealing the chassis against water ingress. This is where the layered nature of 3D printing is a drawback. Even with several treatments of paint and sealant, [Simon] has been unable to stop water getting inside the drone. Further problems concern the excess amount of ballast required to counteract the drone’s natural buoyancy due to displacement.

Regardless of the struggles, we look forward to seeing the next revision rectify some of the shortcomings of the current build. We’re sure [Simon’s] experience building an electric surfboard will come in handy. Video after the break.

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Remoticon Video: Circuit Sculpture Workshop

December 3, 2020 by 1 Comment

Circuit Sculpture was one of our most anticipated workshops of Hackaday Remoticon 2020, and now it’s ready for those who missed it to enjoy. A beginning circuit sculptor could hardly ask for more than this workshop, which highlights three different approaches to building firefly circuit sculptures and is led by some of the most prominent people to ever bend brass and components to their will — Jiří Praus, Mohit Bhoite, & Kelly Heaton.

For starters, you’ll learn the different tools and techniques that each of them uses to create their sculptures. For instance, Kelly likes to use water-based clay to hold components in specific orientations while forming the sculpture and soldering it all together. Jiří and Mohit on the other hand tend to use tape. The point is that there is no right or wrong way, but to instead have all of these tips and tricks under your belt as you sculpt. And that’s what this workshop is really about.

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Crossed Wires Crash Rockets

December 3, 2020 by 69 Comments

On November 17th, a Vega rocket lifted off from French Guiana with its payload of two Earth observation satellites. The booster, coincidentally the 17th Vega to fly, performed perfectly: the solid-propellant rocket engines that make up its first three stages burned in succession. But soon after the fourth stage of the Vega ignited its liquid-fueled RD-843 engine, it became clear that something was very wrong. While telemetry showed the engine was operating as expected, the vehicle’s trajectory and acceleration started to deviate from the expected values.

There was no dramatic moment that would have indicated to the casual observer that the booster had failed. But by the time the mission clock had hit twelve minutes, there was no denying that the vehicle wasn’t going to make its intended orbit. While the live stream hosts continued extolling the virtues of the Vega rocket and the scientific payloads it carried, the screens behind them showed that the mission was doomed.

Displays behind the hosts clearly showed Vega wasn’t following the planned trajectory.

Unfortunately, there’s little room for error when it comes to spaceflight. Despite reaching a peak altitude of roughly 250 kilometers (155 miles), the Vega’s Attitude Vernier Upper Module (AVUM) failed to maintain the velocity and heading necessary to achieve orbit. Eventually the AVUM and the two satellites it carried came crashing back down to Earth, reportedly impacting an uninhabited area not far from where the third stage was expected to fall.

Although we’ve gotten a lot better at it, getting to space remains exceptionally difficult. It’s an inescapable reality that rockets will occasionally fail and their payloads will be lost. Yet the fact that Vega has had two failures in as many years is somewhat troubling, especially since the booster has only flown 17 missions so far. A success rate of 88% isn’t terrible, but it’s certainly on the lower end of the spectrum. For comparison, boosters such as the Soyuz, Falcon 9, and Atlas have success rates of 95% or higher.

Further failures could erode customer trust in the relatively new rocket, which has only been flying since 2012 and is facing stiff competition from commercial launch providers. If Vega is to become the European workhorse that operator Arianespace hopes, figuring out what went wrong on this launch and making sure it never happens again is of the utmost importance.

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Cheap DIY High Impedance Earphones

December 3, 2020 by 18 Comments

Crystal radios can feel magical, given their ability to tune in audio from distant stations with nothing but the energy from the radio signal itself. However, to achieve this feat, they typically rely on a high-impedance earphone to produce an audible sound with very little current. These earphones are hard to find, and thus can be expensive. However, [Billy] figured out a way to build them on the cheap. 

The build starts with a common piezoelectric buzzer. It’s torn down and the extraneous circuitry inside is removed. The piezo element itself is then directly hooked up to a mono audio jack for use with one of [Billy’s] crystal radios. To make it into a usable earpiece, the tip of a pen is cut off and glued to the buzzer’s plastic housing. Then, a rubber in-ear cup from regular modern earbuds is used to ensure a tight, comfortable fit in the ear.

It’s a great way to build something that’s now hard to source, and we bet that [Billy’s] design is more comfortable than the hard plastic models that shipped in Radio Shack kits in the 90s. Of course, there’s other ways to build high-impedance drivers, as we’ve featured before. And, if you’re looking to build a crystal radio, it’s hard to go past [Billy’s] credit card chip build. Video after the break.

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Game Cartridges And The Technology To Make Data Last Forever

December 3, 2020 by 69 Comments

Game cartridges are perhaps the hardiest of all common storage schemes. Short of blunt traumatic force or application of electrical surges to the cartridge’s edge connectors, damaging a game cartridge is hard to do by accident. The same is also true for the data on them, whether one talks about an Atari 2006 cartridge from the late 1970s or a 1990s Nintendo 64 cartridge.

The secret sauce here are mask ROMs (MROM), which are read-only memory chips that literally have the software turned into a hardware memory device. A mask layer unique to each data set is used when metalizing the interconnects during chip fabrication. This means that the data stored on them is as durable as the processor in the game console itself. Yet this is not a technology that we can use in our own hobby projects, and it’s not available for personal long-term data storage due to the costs associated with manufacturing what is essentially a custom chip.

Despite its value as truly persistent storage, MROM has fallen out of favor over the decades. You may be surprised to find a lot of what’s currently used in the consumer market is prone to data corruption over time spans as short as one year to one decade depending on environmental conditions.

So what are we to do if we need to have read-only data that should remain readable for the coming decades?

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Waveshare’s Pi CM3 Laptop Arrives A Bit Too Late

December 3, 2020 by 20 Comments

The good news it that you can now buy a pretty decent laptop that’s based around the Raspberry Pi Compute Module (CM). The bad news is that it was conceived before anyone knew the interface was going to change for the new CM4, so it doesn’t have any of the features that would make it really interesting such as support for PCI-Express. Oh, and it costs $300.

Waveshare, the company that most of us know best as a purveyor of e-paper displays, also made some rather interesting design choices on their laptop. See that black pad under the keyboard? No, it’s not a trackpad. It’s just a decorative cover that you remove to access an LED matrix and GPIO connectors. Make no mistake, a laptop that features a GPIO breakout right on the front is definitely our jam. But the decision to install it in place of the trackpad, and then cover it with something that looks exactly like a trackpad, is honestly just bizarre. It might not be pretty, but the Pi 400 seemed to have solved this problem well enough without any confusion.

On the other hand, there seems to be a lot to like about this product. For one, it’s a very sleek machine that doesn’t have the boxy and somewhat juvenile look that seems so common in other commercial Pi laptops. We also like that Waveshare included a proper Ethernet jack, something that’s becoming increasingly rare even on “real” laptops. As [ETA PRIME] points out in the video after the break, the machine also has a crisp IPS display and a surprisingly responsive keyboard. Though the fact that it still has a “Windows” key borders on being offensive considering how much it costs.

But really, the biggest issue with this laptop is when it finally hit the market. If Waveshare had rushed this out when the CM3 was first introduced, it probably would have been a more impressive technical achievement. On the other hand, had they waited a bit longer they would have been able to design it around the far more capable CM4. As it stands, the product is stuck awkwardly in the middle.

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Exhaust Fan-Equipped Reflow Oven Cools PCBs Quickly

December 3, 2020 by 6 Comments

With reflow soldering, sometimes close is good enough. At the end of the day, the home gamer really just needs a hot plate or an old toaster oven and a calibrated Mark I eyeball to get decent results. This exhaust fan-equipped reflow oven is an attempt to take control of what’s perhaps the more challenging part of the reflow thermal cycle — the cool down.

No fan of the seat-of-the-pants school of reflow soldering, [Nabil Tewolde] started with a cast-off toaster oven for what was hoped to be a more precise reflow oven. The requisite temperature sensors and solid-state relays were added, along with a Raspberry Pi Zero W and a small LCD display. Adding the cooling assist started by cutting a gaping hole cut in the rear wall of the oven, which was then filled with a short stretch of HVAC duct and a stepper-controlled damper. The far end of the duct was fitted with a PC cooling fan; while it seems sketchy to use a plastic fan to eject hot air from the oven, [Nabil] says the exhaust isn’t really that hot by the time it gets to the fan. At the end of the reflow phase of the thermal profile, the damper opens and the fan kicks on, rapidly cooling the oven’s interior.

Unfortunately, [Nabil] still needs to crack open the oven door to get decent airflow; seems like another damper to admit fresh air would help with that. That would complicate things a bit, but it still wouldn’t be as over-the-top as some reflow builds we’ve seen. Then again, that calibrated eyeball thing can work pretty well too, even without a toaster oven.

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