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Hackaday Links: June 20, 2021

June 20, 2021 by 15 Comments

The hits just keep coming for Elon Musk, as this week Starlink users reported their new satellite dishes apparently can’t take the heat. Granted, the places these reports are coming from are really, really hot, like Topock, Arizona, where one Starlink beta tester is located and where the air temperature is expected to hit 123°F (50°C) on Saturday. One user contacted Starlink customer service and was told that Dishy McFlatface is programmed to shut down if the surface temperature exceeds 50°C, which even in non-Arizona locations would be easily exceeded on a rooftop or in an urban heat island. Users experiencing thermal shutdown are taking extreme measures to get back online in the heat of the day, like by setting up sprinklers to water-cool their dishes. Others are building solar shades, and one die-hard is even considering putting the dish on an antenna tower, to get it up into the relatively cooler air above the ground. But these are just workarounds, and according to the engineer who did the Starlink teardown we featured a while back, the permanent fix may just be to redesign the thermal management. In other words, this isn’t likely to be another one of those problems that gets fixed with an OTA software push. Which is probably to be expected for something that’s still in the “Better than Nothing Beta” release.

We’ve all heard that AI and robots are going to replace pretty much every job at some point, but if one customer’s experience with an AI drive-through window is any gauge, it might take quite a while to get there. In a video posted on TikTok (we know, we know), a customer at a Chicago-area McDonald’s showed that the fast-food giant put exactly zero effort into making the experience anything but engaging. The synthesized voice is creepy, and evokes all the wrong kinds of feelings, like the ones you get when you’re forced to use a voice-response system to get through “voice mail jail”. At least in those cases, the voice at least sounds semi-apologetic when it can’t understand what you’ve said. After listening to it once, we’d much rather have a real human, even if it is a surly teen. This seems like a missed opportunity by McDonald’s, which probably has the resources to put a little humanity into their AI.

A while back, we dropped a link about satellites made largely of wood. At the time it seemed interesting if a bit self-serving, since the effort was largely backed by a large Finnish plywood company. And while that aspect of the project hasn’t changed, we’ve now got a better idea of how the WISA Woodsat is put together, and what it will do once it flies later this year. To be clear, the 1U CubeSat is not 100% wood, which of course would make including any electronics problematic. Instead, the side and top panels of the satellite are made from plywood, which are attached to aluminum rails that integrate with the launcher on the mothership. There’s also a metal pantograph-style selfie-stick, because pics or it didn’t happen. The interesting bit is the pre-treatment of the birch plywood, which is dried in a thermal vacuum chamber to prevent outgassing in space. Additionally, the exterior surface of the wood panels was covered with a thin layer of aluminum oxide, to give the surface a chance against highly reactive atomic oxygen. There will be sensors inside the satellite to see if any outgassing occurs, so we could actually get some valuable data about using wood in satellites out of what otherwise could have been just a publicity stunt.

As our long global nightmare appears to be playing out its endgame, and as the world begins to reopen itself to normal pursuits, it’s nice to see that some cons and meetups are actually returning to meatspace. One such event will be BornHack 2021, that week-long campout in a Danish forest with hundreds of like-minded hackers, tinkerers, and artists. The Call for Participation deadline has been extended to July 1, which gives you just a little more time to consider giving a presentation. We’ve heard Jenny List speak glowingly of BornHack, and it actually looks like a lot of fun.

And finally, it’s said that one can never include too many comments when writing code. Not everyone feels that way, of course; I once had a co-worker complain that I commented my code too much, which of course meant that I redoubled my efforts to make sure I had as many comments as possible. That meant I often ran out of ideas for pithy, pertinent, and gratuitous comments to sprinkle into my code. It’s a shame What The Commit didn’t exist back then. Just click the link and you’ll get a fresh, auto-generated comment ready to copy into your commits or embed in your code. Have fun!

Raspberry Pi Hat Adds SDR With High Speed Memory Access

June 20, 2021 by 57 Comments

An SDR add-on for the Raspberry Pi isn’t a new idea, but the open source cariboulite project looks like a great entry into the field. Even if you aren’t interested in radio, you might find the project’s use of a special high-bandwidth memory interface to the Pi interesting.

The interface in question is the poorly-documented SMI or Secondary Memory Interface. [Caribou Labs] helpfully provides links to others that did the work to figure out the interface along with code and a white paper. The result? Depending on the Pi, the SDR can exchange data at up to 500 Mbps with the processor. The SDR actually uses less than that, at about 128 Mbps. Still, it would be hard to ship that much data across using conventional means.

On the radio side, the SDR covers 389.5 to 510 MHz and 779 to 1,020 MHz. There’s also a wide tuning channel from 30 MHz to 6 GHz, with some exclusions. The board can transmit at about 14 dBm, depending on frequency and the receive noise figure is under 4.5 dB for the lower bands and less than 8 dB above 3,500 MHz. Of course, some Pis already have a radio, but not with this kind of capability. We’ve also seen SMI used to drive many LEDs.

Tiny Tesla Valves Etched In Glass

June 20, 2021 by 8 Comments

While it’s in vogue right now to name fancy new technology after Tesla, the actual inventor had plenty of his own creations that would come to bear his namesake, including Tesla coils, Tesla oscillators, Tesla turbines and even the infamous Tesla tower. One of the lesser known inventions of his is the Tesla valve, a check valve that allows flow in one direction without any moving parts, and [Huygens Optics] shows us a method of etching tiny versions of these valves into glass.

The build starts out with a fairly lengthy warning, which is standard practice when working with hydroflouric acid. The acid is needed to actually perform the etching, but it’s much more complicated than a typical etch due to the small size of the Tesla valves. He starts by mixing a buffered oxide etch, a mix of the hydroflouric acid, ammonia, and hydrochloric acid, which gives a much more even etching than any single acid alone. Similar to etching PCBs, a protective mask is needed to ensure that the etch only occurs where it’s needed. For that there are several options, each with their own benefits and downsides, but in the end [Huygens Optics] ends up with one of the smallest Tesla valves ever produced.

In fact, the valves are so small that they can only be seen with the aid of a microscope. While viewing them under the microscope he was able to test with a small drop of water to confirm that they do work as intended. And, while the valves that he is creating in this build are designed to work on liquids, [Huygens Optics] notes that the reason for making them this small was to make tiny optical components which they are known for.

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19 Coils Make Charging Wireless

June 20, 2021 by 57 Comments

Wireless charging is conceptually simple. Two coils form an ad hoc transformer with the primary in the charger and the secondary in the charging device. However, if you’ve ever had a wireless charging device, you know that reality can be a bit more challenging since the device must be positioned just so on the charger. Xiaomi has a multi-coil charger that can charge multiple devices and is tolerant of their positioning on the charger. How does it work? [Charger Lab] tears one apart and finds 19 coils and a lot of heat management crammed into the device.

The first part of the post is a terse consumer review of the device, looking at its dimensions and features. But the second part is when the cover comes off. The graphite heat shield looks decidedly like an accidental spill of something, but we’re sure that’s just how it appears. The coils are packed in tight in three layers. We have to wonder about their mutual interactions, and we assume that only some of them are active at any given time. The teardown shows a lot of the components and even pulls datasheets on many components, but doesn’t really go into the theory of operation.

Still, this is an unusual device to see from the inside. It is impressive to see so much power and thermal management in such a tiny package. We wonder that we don’t see more wireless charging in do-it-yourself projects. We do see some, of course. Not to mention grafting a charging receiver to an existing cell phone.

Compact M&M Sorter Goes Anywhere

June 20, 2021 by 12 Comments

Let’s face it — eating different colored candy like M&Ms or Skittles is just a little more fun if you sort your pile by color first. The not-fun part is having to do it by hand. [Jackofalltrades_] decided to tackle this time-worn problem for engineering class because it’s awesome and it satisfies the project’s requirement for sensing, actuation, and autonomous sequencing. We’d venture to guess that it satisfies [Jackofalltrades_]’ need for chocolate, too.

Here’s how it works: one by one, M&Ms are selected, pulled into a dark chamber for color inspection, and then dispensed into the proper cubby based on the result. [Jackofalltrades_] lived up to their handle and built a color-detecting setup out of an RGB LED and light-dependent resistor. The RGB LED shines red, then, green, then blue at full brightness, and takes a voltage reading from the photocell to figure out the candy’s color. At the beginning, the machine needs one of each color to read in and store as references. Then it can sort the whole bag, comparing each M&M to the reference values and updating them with each new M&M to create a sort of rolling average.

We love the beautiful and compact design of this machine, which was built to maximize the 3D printer as one of the few available tools. The mechanical design is particularly elegant. It cleverly uses stepper-driven rotation and only needs one part to do most of the entire process of isolating each one, passing it into the darkness chamber for color inspection, and then dispensing it into the right section of the jar below. Be sure to check out the demo after the break.

Need a next-level sorter? Here’s one that locates and separates the holy grail of candy-coated chocolate — peanut M&Ms that didn’t get a peanut.

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A Mini USB Display For Your PC Desktop

June 20, 2021 by 22 Comments

By now it’s likely that most Hackaday readers will be used to USB display adapters, in their most common form channeling DisplayPort over the ubiquitous serial interface. Connecting to projectors and other screens with a laptop becomes a breeze, and gone are the days of “Will my laptop work in the venue” stress for people delivering presentations. [Avra Mitra]’s STM32 tiny monitor may not ascend to these giddy heights, but it does at least live up to the promise of reproducing a desktop onto a small colour LCD hooked up through a USB port.

Not through any DisplayPort wizardry though, instead it relies on a Python script that takes successive screen grabs and streams them through USB to the microcontroller, which in tun puts them on the display. It’s claimed to achieve 6 to 7 frames per second as you can see in the video below, with an admission that there remains a huge scope for improvement.

Notwithstanding its limited utility at the moment, we can see that maybe this idea could have its uses in a very basic display after a few improvements. Meanwhile, more conventional monitors take the established route of pairing a dedicated controller board with an LCD panel.

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Apollo Shift Register Is Discrete

June 19, 2021 by 10 Comments

We’re unabashed fans of [Ken Shirriff] here at Hackaday, and his latest post about an Apollo-era transistorized shift register doesn’t disappoint. Of course, nowadays a 16-bit shift register is nothing special. But in 1965, this piece of Apollo test hardware weighed five pounds and likely cost at least one engineer’s salary in the day, if not more.

The incredible complexity of the the Apollo spacecraft required NASA to develop a sophisticated digital system that would allow remote operators to execute tests and examine results from control rooms miles away from the launch pad.

This “Computer Buffer Unit” was used to hold commands for the main computer since a remote operator could not use the DSKY to enter commands directly. Externally the box looks like a piece of military hardware, and on the inside has six circuit boards stacked like the pages of a book. To combat Florida’s notoriously damp conditions, the enclosure included a desiccant bag and a way to fill the device with nitrogen. A humidity indicator warned when it was time to change the bag.

There is a lot more in the post, so if you are interested in unusual construction techniques that were probably the precursor to integrated circuits, diode transistor logic, or just think old space hardware is cool, you’ll enjoy a peek inside this unusual piece of gear. Be sure to check out some of [Ken]’s previous examinations, from tiny circuits to big computers.