Incandescent 7-Segment Displays Are Awesome

April 20, 2021 by Lewin Day 16 Comments

When we think of 7-segment displays as the ubiquitous LED devices that sprung into popularity in the 1970s. However, numbers have existed for a lot longer than that, and people have wanted to know what the numbers are for quite some time, too. Thus, a variety of technologies were used prior to the LED – such as these magnificent incandescent 7-segment displays shown off by [Fran Blanche].

The displays are basic in concept, but we imagine a little frustrating in execution. Electronics was tougher back in the days when valves needed huge voltages and even a basic numerical display drew a load of current. Built to industrial-grade specifications, they’re complete with a big heatsinking enclosure and rugged gold-plated connectors. [Fran] surmises that due to the likely military applications of such hardware, the filaments in the bulbs were likely built in such a way as to essentially last indefinitely. The glow of the individual segments has a unique look versus their LED siblings; free of hotspots and the usual tapered shape on each segment. Instead, the numerals are pleasingly slab-sided for a familiar-but-not-quite aesthetic.

[Fran] demonstrates the display running with a CD4511B BCD-to-7-segment decoder, hooked up with a bunch of 3904 power transistors to get the chip working with filament bulbs instead of LEDs. It’s a little fussy, but the displays run great with the hardware sorted.

We’d love to see these used on a very heavy ridiculous watch; nixies aren’t the only game in town after all. If you do happen to make one, be sure to let us know. Video after the break.

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A Superheterodyne Receiver With A 74xx Twist

April 19, 2021 by Dan Maloney 27 Comments

In a world with software-defined radios and single-chip receivers, a superheterodyne shortwave radio might not exactly score high on the pizzazz scale. After all, people have been mixing, filtering, and demodulating RF signals for more than a century now, and the circuits that do the job best are pretty well characterized. But building the same receiver using none of the traditional superhet trappings? Now that’s something new.

In what [Micha] half-jokingly calls a “74xx-Defined Radio”, easily obtained discrete logic chips, along with some op-amps and a handful of simple components, take the place of the tuned LC circuits and ganged variable capacitors that grace a typical superhet receiver. [Micha] started by building an RF mixer out of a 74HC4051 analog multiplexer, which with the help of a 2N3904 phase splitter forms a switching mixer. The local oscillator relies on the voltage-controlled oscillator (VCO) in a 74HC4046 PLL, a chip that we’ve seen before in [Elliot Williams]’ excellent “Logic Noise” series. The IF filter is a simple op-amp bandpass filter; the demodulator features an op-amp too, set up as an active half-wave rectifier. No coils to wind, no capacitors to tune, no diodes with mysterious properties — and judging by the video below, it works pretty well.

It may not be the most conventional way to tune in the shortwave bands, but we always love the results of projects that are artificially constrained like this one. Hats off to [Micha] for the interesting trip down the design road less travelled.

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Extinguish Squeaks 24/7 With Refillable WD-40

April 1, 2021 by Kristina Panos 43 Comments

It’s 10:34PM and you’ve just run out of water displacement formula #40. You could wait until tomorrow to get a new can, or you could spend the rest of the night turning an old, empty fire extinguisher into a refillable and re-pressurizable WD-40 dispenser like [liquidhandwash] did. The part count is pretty low, but it’s awfully specific.

And the emphasis is on empty extinguisher. Part of the deal involves twisting the gauge off, and we wouldn’t want you to get blasted in the face with any last gasps of high-powered firefighting foam. In order to make the thing re-pressurizable, [liquidhandwash] stripped all the rubber from a tire valve and removed the core temporarily so it could be soldered into the fitting where the gauge was. The handy hose is from a large can of WD-40, which is also where the label came from — since it’s no longer a fire extinguisher, it needs to stop bearing resemblance to one, so [liquidhandwash] removed the sticker, painted it blue, and glued the cut-open can to the outside.

To use it, [liquidhandwash] fills it up about halfway and then pressurizes it through the tire valve with a bike pump or compressor. (We think we’d go with bike pump.) Since [liquidhandwash] goes through so much lubricant, now, they can just buy it by the gallon and keep refilling the extinguisher.

Is WD-40 your everything hammer? Variety is the spice of shop life.

Video Ram Transplant Doubles RTX 3070 Memory To 16 GB

March 20, 2021 by Mike Szczys 31 Comments

Making unobtainium graphics cards even more unobtainable, [VIK-on] has swapped out the RAM chips on an Nvidia RTX 3070. This makes it the only 3070 the world to work with 16 GB.

If this sounds familiar, it’s because he tried the same trick with the RTX 2070 back in January but couldn’t get it working. When he first published the video showing the process of desoldering the 3070’s eight Hynix 1 GB memory chips and replacing them with eight Samsung 2 GB chips he hit the same wall — the card would boot and detect the increased RAM, but was unstable and would eventually crash. Helpful hints from his viewers led him to use an EVGA configuration GUI to lock the operating frequency which fixed the problem. Further troubleshooting (YouTube comment in Russian and machine translation of it) showed that the “max performance mode” setting in the Nvidia tool is also a solution to stabilize performance.

The new memory chips don’t self-report their specs to the configuration tool. Instead, a set of three resistors are used to electronically identify which hardware is present. The problem was that [VIK-on] had no idea which resistors and what the different configurations accomplished. It sounds like you can just start changing zero Ohm resistors around to see the effect in the GUI, as they configure both the brand of memory and the size available. The fact that this board is not currently sold with a 16 GB option, yet the configuration tool has settings for it when the resistors are correctly configured is kismet.

So did it make a huge difference? That’s difficult to say. He’s running some benchmarks in the video, both Unigine 2 SuperPosition and 3DMark Time Spy results are shown. However, we didn’t see any tests run prior to the chip swap. This would have been the key to characterizing the true impact of the hack. That said, reworking these with a handheld hot air station, and working your way through the resistor configuration is darn impressive no matter what the performance bump ends up being.

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Running 57 Threads At Once On The Arduino Uno

March 17, 2021 by Lewin Day 44 Comments

When one thinks of the Arduino Uno, one thinks of a capable 8-bit microcontroller platform that nonetheless doesn’t set the world alight with its performance. Unlike more modern parts like the ESP32, it has just a single core and no real multitasking abilities. But what if one wanted to run many threads on an Uno all at once? [Adam] whipped up some code to do just that.

Threads are useful for when you have multiple jobs that need to be done at the same time without interfering with each other. The magic of [Adam]’s ThreadHandler library is that it’s designed to run many threads and do so in real time, with priority management as well. On the Arduino Uno, certainly no speed demon, it can run up to 57 threads concurrently at 6ms intervals with a minumum timing error of 556 µs and a maximum of 952 µs. With a more reasonable number of 7 threads, the minimum error drops to just 120 µs. Each thread comes with an estimated overhead of 1.3% CPU load and 26 bytes of RAM usage.

While we struggle to think of what we could do with more than a handful of threads on an Arduino Uno, we’re sure you might have some ideas – sound off in the comments. ThreadHandler is available for your perusal here, and runs on SAMD21 boards as well as any AVR-based boards that are compatible with TimerOne. We’ve seen other work in the same space before, such as ChibiOS for the Arduino platform. Video after the break.

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Hackaday Links: March 7, 2021

March 7, 2021 by Dan Maloney 13 Comments

It’s March, which means Keysight is back in the business of giving away a ton of test gear. Keysight University Live starts on March 15, with daily events the first week followed by a string of weekly live events through April. We always enjoy these Keysight events; sure, they’re clearly intended to sell more gear, but the demos and tutorials are great, and we always learn a lot. There’s also a feeling of community that feels similar to the Hackaday community; just a bunch of electronics nerds getting together to learn and share. If you’re interested in that community, or even if you’re just looking for a chance to win something from the $300,000 pile of goodies, you’ll need to register.

There’s another event coming up that you’ll want to know about: the 2021 Open Hardware Summit. Because 2021 is the new 2020, the summit is being held virtually again, this year on April 9. Tickets are on sale now, and we’re told there are still plenty of Ada Lovelace Fellowships available to those who consider themselves to be a minority in tech. The Fellowship covers the full cost of a ticket; it usually covers travels costs too, but sadly we’re still not there yet.

Once we do start traveling again, you might need to plan more carefully if cities start following the lead of Petaluma, California and start banning the construction of gas stations. The city, about 40 miles (64 km) north of San Francisco, is believed to be the first city in the United States to ban new gas station construction. The city council’s decision also prevents gas station owners from expanding, reconstructing, or relocating existing gas stations. The idea is to create incentives to move toward non-fossil fuel stations, like electric vehicle charging stations and hydrogen fueling. Time will tell how well that works out.

Go home Roomba — you’re drunk. That could be what Roomba owners are saying after an update semi-bricked certain models of the robotic vacuum cleaners. Owners noted a variety of behaviors, like wandering around in circles, bumping into furniture, and inability to make its way back to base for charging. There’s even a timelapse on reddit of a Roomba flailing about pathetically in a suspiciously large and empty room. The drunken analogy only goes so far, though, since we haven’t seen any reports of a Roomba barfing up the contents of its dust bin. But we’re still holding out hope.

And finally, if you’re not exactly astronaut material but still covet a trip to space, you might luck out courtesy of Japanese billionaire Yusaku Maezawa. He’s offering to pay the way for eight people from around the world on a planned flight to the Moon and back in 2023. Apparently, Maezawa bought up all the seats for the flight back in 2018 with the intention of flying a group of artists to space. His thinking has changed, though, and now he’s opening up the chance to ~~serve as ballast~~ join the crew to pretty much any rando on the planet. Giving away rides on Starship might be a harder sell after this week’s test, but we’re sure he’ll find plenty of takers. And to be honest, we wish the effort well — the age of routine civilian space travel can’t come soon enough for us.

X-Ray Defeats Letterlocking — Unfolds And Reads Letter Sealed Since 1697

March 6, 2021 by Jenny List 24 Comments

Over recent years we’ve been treated to a series of fascinating advances in the world of x-ray imaging, as researchers have developed their x-ray microtomography techniques and equipment to the point at which they can probe and then computationally reconstruct written material within objects such as letters or scrolls in museum collections whose value or fragility means they can’t be opened and read conventionally. There is more to this challenge than simply extracting the writing though, in addition to detecting the ink the researchers also have to unpick the structure of whatever it was written upon. A particular challenge comes from letterpackets, the art of folding a letter into its own envelope, and a newly-published Nature Communications paper details work from a team of academics in the USA, the UK, and the Netherlands in tackling it.

Letterpackets were more than a practical method of packaging a missive for the mail, they also had a security function often called Letterlocking. A packet would be folded in such a way as to ensure it was impossible to open without tearing or otherwise damaging the paper, and their structure is of especial interest to historians. The researchers had a unique resource with which to work; the Brienne collection is a trunk full of undeliverable mail amassed by a 17th century postmaster couple in Den Haag in the Netherlands, and now in the possession of the Beeld en Geluid museum in that city. In it were a cache of letters including 577 never-opened letterpackets, and the x-ray technique promised a means to analyse these without compromising them.

The researchers have developed an entirely computational technique for the virtual unfolding process. Starting with a 3D volumetric x-ray scan of the unopened packet they then identify the various layers of paper and the bright spots which denote the ink. Their algorithm has to cope with areas in which two or more layers are tightly in contact, for example when multiple levels are folded, and then unpick the resulting 3-dimensional mesh into a 2-dimensional sheet. Their process for mapping the crease pattern involves applying a colour map representing the mean curve radius at a given point. The final section of the paper looks at the multiple different methods of letterlocking, and attempts to categorise them all including a security rating for each. It’s evident that this could be a highly personalised process, indeed they give as an example a letter from Mary Queen of Scots that used an intricate spiral folding technique to identify its sender.

It’s clear that this technique will reveal many more fascinating historical documents as it is both refined and extended across the many more collections of further artefacts that have lain waiting for it. As they say, individual letters do not necessarily contain earth-shattering historical discoveries, but taken together they shed an important light on the social history of past centuries.

One of the names on the paper is [David Mills], whose work has featured here before.