Rolling Your Own LED Matrix Driver, With Copper Foil Tape To The Rescue

It all started when [Damien Walsh] got his hands on some surplus LED boards. Each panel contained 100 mini-PCBs hosting a single bright LED that were meant to be to be snapped apart as needed. [Damien] had a much better idea: leave them in their 20×5 array and design a driver allowing each LED to be controlled over WiFi. He was successful (a brief demo video is embedded down below after the break) and had a few interesting tips to share about the process of making it from scratch.

The first hurdle he ran into was something most of us can relate to; it’s difficult to research something when one doesn’t know the correct terms. In [Damien]’s case, his searches led him to a cornucopia of LED drivers intended to be used for room lighting or backlights. These devices make a large array of smaller LEDs act like a single larger light source, but he wanted to be able to individually address each LED.

Eventually he came across the IS32FL3738 6×8 Dot Matrix LED Driver IC from ISSI which hit all the right bases. Three of these would be enough to control the 100-LED panel; it offered I2C control and even had the ability to synchronize the PWM of the LEDs across multiple chips, so there would be no mismatched flicker between LEDs on different drivers. As for micontroller and WiFi connectivity, we all have our favorites and [Damien] is a big fan of Espressif’s ESP32 series, and used the ESP32-WROOM to head it all up.

LED pads bridged to copper tape, with Kapton (polyimide) tape insulating any crossovers.

The other issue that needed attention was wiring. Each of the LEDs is on its own little PCB with handy exposed soldering pads, but soldering up 100 LEDs is the kind of job where a little planning goes a long way. [Damien] settled on a clever system of using strips of copper tape, insulated by Kapton (a super handy material with a sadly tragic history.) One tip [Damien] has for soldering to copper tape: make sure to have a fume extractor fan running because it’s a much smokier process than soldering to wires.

A 3D-printed baffle using tracing paper to diffuse the light rounds out the device, yielding a 20 x 5 matrix of individually-controlled rectangles that light up smoothly and evenly. The end result looks fantastic, and you can see it in action in the short video embedded below.

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Psst – Wanna Buy A Control Panel From A Nuclear Power Station?

Doing the rounds today is an interesting lot in an otherwise unexciting industrial dispersal auction in Lincolnshire, UK. On sale is an “Ex nuclear plant reactor control/monitoring system“, at the time of writing attracting the low low bid of £220 ($270), but we guess it will rise. Everyone who has watched Chernobyl (or maybe The Simpsons) is now gazing awestruck at a crescent of metal consoles covered in screens, buttons, and joysticks just waiting for a staff of white-coated technicians to pore over them.

Chernobyl Unit 3 control room (still active). [Source: IAEA Imagebank on Flickr CC-SA 2.0]
It’s a very cool lot indeed, but it raises more questions than it answers. The auction house has very little information indeed, so we’re left guessing, where did it come from? From this image showing the unit 3 control room at Chernobyl it’s obvious didn’t come from there (/s). Since it is for sale in the UK, and the country has decommissioned the majority of its first-generation reactors by now, so there is no shortage of candidates. But that intriguing possibility raises another question. Is it even a reactor control panel in the first place?

British civilian nuclear plants have tight security but they are hardly a secret, so plenty of photos are online showing their interiors. And in studying those we hit a problem, this panel doesn’t resemble any of the control panel images we can find. The first generation of Magnox (Magnetic Oxide Magnesium Non Oxidising) plants had panels covered in analogue dials and chart recorders so it’s unlikely to be one of those. The second-generation AGR (Advanced Gas-cooled Reactor) stations had similarly complex panels, and it’s evidently not one of them.

Looking closely at the photos it becomes apparent that there are a lot of camera controls and monitors, and even what looks like a uMatic video recorder. It’s definitely nuclear-related and the 1980s look of it suggests maybe it could have come from an Advanced Gas-Cooled Reactor (AGR) station, but could it be a little closer to Sector 7G than the centre of the action? Is it a video monitoring console used to keep a physical eye on its operation?

Be careful if you bid, you could end up with a rather cool but absurdly large 1980s CCTV system. Can any of our readers shed any light on the matter?

Thanks [Gregg “Cabe” Bond] for the tip.

Hackaday Links: March 15, 2020

Just a few weeks ago in the Links article, we ran a story about Tanner Electronics, the Dallas-area surplus store that was a mainstay of the hacker and maker scene in the area. At the time, Tanner’s owners were actively looking for a new, downsized space to move into, and they were optimistic that they’d be able to find something. But it appears not to be, as we got word this week from James Tanner that the store would be shutting its doors after 40 years in business. We’re sad to see anyone who’s supported the hardware hacking scene be unable to make a go of it, especially after four decades of service. But as we pointed out in “The Death of Surplus”, the center of gravity of electronics manufacturing has shifted dramatically in that time, and that’s changed the surplus market forever. We wish the Tanner’s the best of luck, and ask those in the area to stop by and perhaps help them sell off some of their inventory before they close the doors on May 31.

Feel like getting your inner Gollum on video but don’t know where to begin? Open source motion capture might be the place to start, and Chordata will soon be here to help. We saw Chordata as an entry in the 2018 Hackaday Prize; they’ve come a long way since then and are just about to open up their Kickstarter. Check out the video for an overview of what Chordata can do.

Another big name in the open-source movement has been forced out of the organization he co-founded. Eric S. Raymond, author of The Cathedral and the Bazaar and co-founder and former president of the Open Source Initiative has been removed from mailing lists and banned from communicating with the group. Raymond, known simply as ESR, reports that this was in response to “being too rhetorically forceful” in his dissent from proposed changes to OSD, the core documents that OSI uses to determine if software is truly open source. Nobody seems to be saying much about the behavior that started the fracas.

COVID-19, the respiratory disease caused by the newly emerged SARS-CoV-2 virus, has been spreading across the globe, causing panic and claiming lives. It’s not without its second-order effects either, of course, as everything from global supply chains to conferences and meetings have been disrupted. And now, coronavirus can be blamed for delaying the ESA/Russian joint ExoMars mission. The mission is to include a Russian-built surface platform for meteorological and biochemical surveys, plus the ESA’s Rosalind Franklin rover. Program scientists are no longer able to travel and meet with their counterparts to sort out issues, severely crimping productivity and forcing the delay. Social distancing and working from home can only take you so far, especially when you’re trying to get to Mars. We wonder if NASA’s Perseverance will suffer a similar fate.

Speaking of social distancing, if you’ve already decided to lock the doors and hunker down to wait out COVID-19, you’ll need something to keep you from going stir crazy. One suggestion: learn a new skill, like PCB design. TeachMePCB is offering a free rigid PCB design course starting March 28. If you’re a newbie, or even if you’ve had some ad hoc design experience, this could be a great way to productively while away some time. And if that doesn’t work for you, check out Bartosz Ciechanowski’s Gears page. It’s an interactive lesson on why gears look like they do, and the math behind power transmission. Ever wonder why gear teeth have an involute shape? Bartosz will fix you up.

Stay safe out there, everyone. And wash those hands!

Hackaday Links: February 2, 2020

Is it just me or did January seem to last for about three months this year? A lot has happened since the turn of the decade 31 days ago, both in the normie world and in our space. But one of the biggest pieces of news in the hacker community is something that won’t even happen for four more months: Hackaday Belgrade. The annual conference in Hackaday’s home-away-from-home in Serbia was announced, and as usual, one had to be a very early bird to score discount tickets. Regular tickets are still on sale, but I suspect that won’t last long. The call for proposals for talks went out earlier in the month, and you should really consider standing up and telling the world what you know. Or tell them what you don’t know and want to find out – there’s no better way to make connections in this community, and no better place to do it.

Someone dropped a tip this week about the possible closing of Tanner Electronics, the venerable surplus dealer located in Carrollton, Texas, outside of Dallas and right around the corner from Dallas Makerspace. The report from someone visiting the store is that the owner has to either move the store or close it down. I spoke to someone at the store who didn’t identify herself, but she confirmed that they need to either downsize or close. She said they’re actively working with a realtor and are optimistic that they’ll find a space that fits their needs, but the clock is ticking – they only have until May to make the change. We covered Tanner’s in a 2015 article on “The Death of Surplus”. It would be sad to lose yet another surplus store; as much as we appreciate being able to buy anything and everything online, nothing beats the serendipity that can strike walking up and down aisles filled with old stuff. We wish them the best of luck.

Are you finding that the smartphone in your pocket is more soul-crushing than empowering? You’re not alone, and more and more people are trying a “digital detox” to free themselves from the constant stimulation. And there’s no better way to go about this than by turning your smartphone into a not-so-smart phone. Envelope, a  paper cocoon for your phone, completely masks the screen, replacing it with a simple printed keypad. A companion app allows you to take and make phone calls or use the camera, plus provides a rudimentary clock, but that’s it. The app keeps track of how long you can go before unwrapping your phone and starting those sweet, sweet dopamine hits again. It reminds us a bit of the story we also saw this week about phone separation anxiety in school kids, and the steps schools are taking to mitigate that problem.

We saw a lot of articles this week on a LoRaWAN security vulnerability. The popular IoT network protocol has been billed as “secure by default”, but a white paper released by cybersecurity firm IOActive found a host of potential attack vectors. Their main beef seems to be that client devices which are physically accessible can be reverse engineered to reveal their encryption keys. They also point out the obvious step of taking the QR code off of client devices so an attacker can’t generate session keys for the device.

And finally, the mummy speaks! If you ever wondered what the voice of someone who lived 3,000 years ago sounded like, wonder no more. Using computed tomography (CT) data, scientists in the UK and Germany have recreated the vocal tract of Nesyamun, an Egyptian scribe and priest from the time of pharaoh Rameses XI. He died in his mid-50s, and his mummified remains have been studied since the 1800s. CT data was used to 3D-print Nesyamun’s larynx and nasopharynx, which was then placed atop a “Vocal Tract Organ”, possibly the strangest musical instrument in existence. The resulting vowel-like utterance is brief, to say the least, but it’s clear and strong, and it’s pretty impressive that we can recreate the voice of someone who lived and died three millennia ago.


An (Almost) Free Apollo-Era Rocket

According to recent news reports, NASA’s Marshall Space Flight Center in Huntsville Alabama wants to give away a piece of history — an engineering test article of a Saturn I Block I booster. The catch? You’ll need to pay to haul it off, which will cost about $250,000. According to C|Net, the offer appears to be for museums and schools, but it’s likely that price tag would probably scare most private buyers off anyway.

On the other hand, if you are a museum, library, school, or university, you can score cheap or free NASA stuff using their GSAXcess portal. In general, you do have to pay shipping. For example, a flexible thermal blanket from the shuttle costs $37.28. A heat tile runs about $25.

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Marquee Display Uses Six Dozen Surplus VFD Tubes To Great Effect

The quest to repurpose surplus parts into new and interesting displays never ends, it seems. And the bigger the display, the better, with extra points for using some really obscure part, like these surplus Russian vacuum-fluorescent tubes turned into a marquee display.

As [tonyp7] freely admits, this is a pet project that’s just for the fun of it, made possible by the flood of surplus parts on the market these days. The VFD tubes are IV-25s, Russian tubes that can be had by the fistful for a song from the usual sources. The seven small elements in the tube were intended to make bar graph displays like VU meters, but [tonyp7] ganged up twelve side by side to make 84-pixel displays. The custom driver board for each matrix needs three of the old SN75518 driver chips, in 40-pin DIPs no less. A 3D-printed bracket holds the tubes and the board for each module; it looks like a clock is the goal, with six modules ganged together. But the marquee display shown below is great too, and we look forward to seeing the finished project.

From faux-Nixies made with LEDs to flip-segment displays driven by relay logic to giant seven-segment LEDs that can be 3D-printed, we really like the trend to unique displays. What are you dreaming up?

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Military Surplus Repurposed For High Energy Physics

Performing high-energy physics experiments can get very expensive, a fact that attracts debate on public funding for scientific research. But the reality is that scientists often work very hard to stretch their funding as far as they can. This is why we need informative and entertaining stories like Gizmodo’s How Physicists Recycled WWII Ships and Artillery to Unlock the Mysteries of the Universe.

The military have specific demands on components for their equipment. Hackers are well aware MIL-SPEC parts typically command higher prices. That quality is useful beyond their military service, which lead to how CERN obtained large quantities of a specific type of brass from obsolete Russian naval ordnance.

The remainder of the article shared many anecdotes around Fermilab’s use of armor plate from decommissioned US Navy warships. They obtained a mind-boggling amount – thousands of tons – just for the cost of transport. Dropping the cost of high quality steel to “only” $53 per ton (1975 dollars, ~$250 today) and far more economical than buying new. Not all of the steel acquired by Fermilab went to science experiments, though. They also put a little bit towards sculptures on the Fermilab campus. (One of the few contexts where 21 tons of steel can be considered “a little bit”.)

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