Day: November 9, 2023

The Eyes Of The Basilisk Are Watching You

November 9, 2023 by 1 Comment

MIT student [Anhad Sawhney] built an interesting decoration for his dorm room corridor called The Eyes of the Basilisk. Named after the mythical creature with a deadly gaze, the project monitors passers-by using thermal cameras and an LED matrix.

The project uses a thermal camera and a 64 by 64 LCD panel, with an ESP32 taking the signal from the thermal camera and processing it to find the largest hot blob in the image, which is (probably) a person. The ESP32 then displays the pixel art basilisk eye image with the iris closest to the blob’s coordinates, updating once a second. With a bit of processing to make the eye appear more spherical, it is a pretty convincing trick.

Most might have built one (or two) of the devices on a breadboard and left it at that, but [Anhad] decided to use the project as a way to teach PCB fabrication to some friends, so they created a PCB that could be mounted onto the back of the LCD matrix and built 14 of them, using the pick & place machine that he had access to at the MIT Media Lab. They then mounted all of them on the wall of his dorm room so the wall appeared to keep track of anyone walking by. I’ve never met a Basilisk, so I don’t know how many eyes they have,  but it has a pretty creepy look as it watches you walking down the corridor.

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Fastest Semiconductor May Also Be Most Expensive

November 9, 2023 by 26 Comments

Scientists have found what they think may be the fastest known semiconductor. Sounds great, right? But it happens to made from one of the rarest elements: rhenium. That rare element combines with selenium and chlorine to form a “superatom.” Unlike conventional semiconductor material, the superatom causes phonons to bind together and resist scattering. This should allow materials that can process signals in femtoseconds,

Rhenium was the last stable element to be found in 1925. It is primarily used in combination with nickel in parts of jet engines, although it is also known as a catalyst for certain reactions. It is very rare and has a high melting point, exceeded only by tungsten and carbon. When it was discovered, scientists extracted a single gram of the material by processing 660 kg of molybdenite. Because of its rarity, it is expensive, costing anywhere from $2,800 to $10,600 per kilogram.

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The Height Of 1960s Dental Electronic Technology

November 9, 2023 by 9 Comments

If you’ve ever been to the dental surgery and found yourself requiring some gum surgery, the chances are you’ll have found your dentist wielding an electronic probe to cauterise the flesh. It’s evidently some form of RF device because you are usually required to hold one of the electrodes while it’s being used, but annoyingly, for an engineer, it’s hardly the time or place to ask how it works. For the curious, then, [Keri Szafir] has the box of tricks behind the probe and is subjecting it to a teardown.

The box on her bench isn’t the one you’ll find in your dentist’s toolkit today, but its distant ancestor from the 1960s that integrates multiple functions into a single box. It’s a very period enclosure with typically 1960s-style vacuum tubes and point-to-point wiring. There’s an HF oscillator using a pair of EL81 power pentodes for that electrode you always wished you could ask your dentist about, and unexpectedly, a thyratron, a type of gas-filled switching tube not dissimilar to a thyristor, in a separate circuit for dental pulp testing. We’re not dental experts here at Hackaday, but [Keri] has done the research and explains the device in the video below the break. At one point, she observes that it’s quite a scary machine to be connected to a living person, and we can concur with that.

Her bench has provided a few projects here in the past, including one of her amplifiers. While it might be fun to tear down a more modern version, you are better off asking for old dental burrs.

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Hack A Soda Can Into Jewelry

November 9, 2023 by 11 Comments

If you’ve ever needed some aluminum for a project, you might have noticed you have easy access to aluminum cans. If you need a cylinder, fine. But what if you don’t? [ThescientistformerlyknownasNaegeli] shows how to create an attractive necklace from two soda cans, and we think the techniques might be usable for other cases where you might need aluminum. If you care more about the necklace, it looks good. You only have to add a 3D-printed clasp or, if you prefer, you can buy a clasp and use that. For the Hackaday crowd, you can also use the resulting structure as an aluminum cable shield, which might better suit you.

The post gives more details and points to other posts for even deeper dives into many of the steps. But the basic idea is you strip the ink from the outside of the can and then cut the can into a strip. The mechanism for that looks a lot like a machine to cut plastic bottles into strips, but that method isn’t feasible without special blades.

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Does Getting Into Your Garage Really Need To Be Difficult?

November 9, 2023 by 78 Comments

Probably the last thing anyone wants when coming home from a long day at work or a trip is to be hassled at the last possible moment — gaining entrance to your house. But for some home automation enthusiasts, that’s just what happened when they suddenly learned that their own garage doors had betrayed them.

The story basically boils down to this: Chamberlain, a US company that commands 60% of the garage door market, recently decided to prevent “unauthorized usage” of their MyQ ecosystem through third-party apps. Once Chamberlain rolled out the change, users of Home Assistant and other unauthorized apps found themselves unable to open or close their doors with the apps they were accustomed to.

Those of us with custom smart home setups can relate to how frustrating it is when something disturbs the systems you’ve spent a lot of time tweaking and optimizing. It’s especially upsetting for users who both Chamberlain hardware specifically because it was supported by Home Assistant, only to have the company decide to drop support. This feels like false advertising, but we strongly suspect that buried in the EULA users must have agreed to at some point is a clause that essentially says, “We can do anything we want and tough noogies to you.” And if you read through the article linked above, you’ll get an idea why Chamberlain did this — they probably didn’t like the idea that users were avoiding their ad-spangled MyQ app for third-party interfaces, depriving them of ad revenue and the opportunity for up-selling.

We feel the frustration of these users, but rather than curse the darkness, perhaps this will light a candle of righteous rage that leads to a clever workaround. The Home Assistant blog article mentions a dongle called ratgdo, which should allow any door with plain old dry contacts to work via MQTT or ESPHome. It’s extra work that users shouldn’t have to put in, but maybe getting one over on The Man would be worth the effort.

Thanks to [KC] for the tip; please keep us posted on your workaround.

Mining And Refining: Graphite

November 9, 2023 by 26 Comments

In my teenage years I worked for a couple of summers at a small amusement park as a ride operator. Looking back on it, the whole experience was a lot of fun, although with the minimum wage at $3.37 an hour and being subjected to the fickle New England weather that ranged from freezing rains to heat stroke-inducing tropical swelter, it didn’t seem like it at the time.

One of my assignments, and the one I remember most fondly, was running the bumper cars. Like everything else in the park, the ride was old and worn out, and maintenance was a daily chore. To keep the sheet steel floor of the track from rusting, every morning we had to brush on a coat of graphite “paint”. It was an impossibly messy job — get the least bit of the greasy silver-black goop on your hands, and it was there for the day. And for the first few runs of the day, before the stuff worked into the floor, the excited guests were as likely as not to get their shoes loaded up with the stuff, and since everyone invariably stepped on the seat of the car before sitting on it… well, let’s just say it was easy to spot who just rode the bumper cars from behind, especially with white shorts on.

The properties that made graphite great for bumper cars — slippery, electrically conductive, tenacious, and cheap — are properties that make it a fit with innumerable industrial processes. The stuff turns up everywhere, and it’s becoming increasingly important as the decarbonization of transportation picks up pace. Graphite is amazingly useful stuff and fairly common, but not all that easy to extract and purify. So let’s take a look at what it takes to mine and refine graphite.

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Programming 1949 Style!

November 9, 2023 by 28 Comments

What was it like to program an early digital computer? [Woven Memories] wanted to know and wants you to know, too. [Maurice Wilkes] and his team wrote a book about their EDSAC and the 18 instructions that it used. These days, you can even run an EDSAC program on a number of emulators.

It is hard to realize how things we take entirely for granted had to be invented by [Wilkes] and his colleagues. The book, “The Preparation of Programs for an Electronic Digital Computers” has, among other things, the first recorded use of a software library and the first API. Even the subroutine needed inventing by [Wilkes’] student [David Wheeler], which was known for a while as the “Wheeler Jump.”

Like many things in old computers, the Wheeler Jump required code to modify itself. Even indexing modes were often implemented by changing an address inside the program.

While we frown on techniques like this today, you have to start somewhere. We are big fans of EDSAC and [Dr. Wilkes] had a long and distinguished career long after EDSAC, too. The original plans for EINIAC led to EDSAC, EDVAC, and a slew of other early machines. You can see a video of the machine with an introduction by [Wilkes] below.

If you want to try your hand with the EDSAC, try your browser. There’s also a very nice Windows emulator that runs fine under WINE.

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