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How Long Can a Quadcopter Drone Fly on Just Solar?

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The final second prototype flying. (Credit: Luke Maximo Bell, YouTube) The dream of fully powering everything from aircraft to cars on just the power generated from solar panels attached to the machine remains a tempting one, but always seems to require some serious engineering including putting the machine on a crash diet. The quadcopter that [Luke Maximo Bell] tried to fly off just solar power is a good case in point, as the first attempt crashed after three minutes and wrecked its solar panels. Now he’s back with a second attempt that ought to stay airborne for as long as the sun is shining. Among the flaws with the first prototype were poor support for the very thin and fragile PV panels, requiring much better support on the carbon fiber frame of the drone. To support the very large solar array, the first drone’s arms were made to be very long, but this interfered with maneuvering, so the second version got trimmed down and the array raised above the frame. This saved 70 gra...
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Studying a Battle Born LFP Battery’s Death Under Controlled Conditions

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The test setup for the Battle Born LFP cycling. (Credit: Will Prowse, YouTube) There has been quite a bit of news recently about the  Battle Born LiFePO 4 (LFP) batteries and how they are dying in droves if not outright melting their plastic enclosures. Although the subsequent autopsies show molten plastic spacers on the bus bars and discolored metal in addition to very loose wiring, it can be educational to see exactly what is happening during repeated charge-discharge cycles at a fraction of the battery’s rated current. Thus [Will Prowse] recently sacrificed another Battle Born 75 Ah LFP battery to the Engineering QA Gods. This time around the battery was hooked up to test equipment to fully graph out the charging and discharging voltage and current as it was put through its paces. To keep the battery as happy as possible it was charged and discharged at a mere 49A, well below its rated 100A. Despite this, even after a mere 14 cycles the battery’s BMS would repeatedly dis...
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Real Robot Makes Debut in Programming Game

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Sometimes the right tool for the right job appears almost out of nowhere. That was certainly the case for [Jonathan] who came across an unusual but well-designed robot at a secondhand shop. The robot needed a bit of work to get back into a usable condition, but after that it was ready for use. For such a unique machine, it needed a unique place to work as well, so in this build [Jonathan] uses it as a real robot to recreate a popular board game meant to teach programming to children. In the original board game, called Robot Turtles , there are no actual robots. Instead, players use cards to control turtles to reach objectives in much the same way that a programmer would solve a similar problem with a computer. A board game with such a name almost demands a robot, so [Jonathan] found a larger playing surface in the form of soft matting blocks, each with a number or letter, that can be assembled into a grid. To make the game, he built a Python application on top of the interface h...
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Retro Weather Display Acts Like It’s Windows 95

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Sometimes you really need to know what the weather is doing, but you don’t want to look at your phone. For times like those, this neat weather display from [Jordan] might come in handy  with its throwback retro vibe. The build is based around the ESP32-2432S028—also known as the CYD, or Cheap Yellow Display, for the integrated 320 x 240 LCD screen. [Jordan] took this all-in-one device and wrapped it in an attractive 3D-printed housing in the shape of an old-school CRT monitor, just… teenier. A special lever mechanism was built in to the enclosure to allow front panel controls to activate the tactile buttons on the CYD board. The ESP32 is programmed to check Open-Meteo feeds for forecasts and current weather data, while also querying a webcam feed and satellite and radar JPEGs from available weather services. These are then displayed on screen in a way that largely resembles the Windows 95 UI design language, with pages for current conditions, future forecasts, wind speeds, and th...
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Reading the World’s Smallest Hard Drive

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You have a tiny twenty-year-old hard drive with a weird interface. How do you read it? If you’re [Will Whang], by reverse engineering, and building an interface board . In many of our portable, mobile, and desktop computers, we’re used to solid-state storage. It’s fast and low power, and current supply-chain price hikes notwithstanding, affordable in the grand scheme of things. It wasn’t always this way though, a couple of decades ago a large flash drive was prohibitively expensive. Hard drive manufacturers did their best to fill the gap with tiny spinning-rust storage devices which led to the smallest of them all: the Toshiba MK4001MTD. It crammed 4 GB onto a 0.85″ platter, and could be found in a few devices such as high-end Nokia phones. Breaking out the Nokia’s hard drive interface. The drive’s connector is a pattern of pads on a flexible PCB, one he couldn’t help noticing had a striking resemblance to an obscure SD card variant. Hooking it up to an SD reader didn’t work unfo...
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Running Windows 98 on the iPAQ IA-2 Internet Appliance

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Devices that were limited to only run a web browser were relatively common around 2000, as many people wanted to surf the Information Super Highway, but didn’t quite want to get a regular PC — being in many ways the retro equivalent of a Chromebook. The Compaq iPAQ IA-2 from 2000 that [Dave Luna] got is no exception , with a Microsoft CE-based OS that is meant to be used with Microsoft Network (MSN) dial-up, which amusingly is still available today. In order to get a more useful OS on it, like Windows 98, you have to jump through quite a few hoops, as [Dave] found out. Although there is an IDE connection on the mainboard, this cannot be booted from, likely due to BIOS limitations. This means that he had to chain boot via the 16 MB NAND Flash drive that the original OS booted from, which was done by writing MS-DOS to the Flash drive using another workaround as it’s not a standard IDE device either. From this you can then boot Windows 98 from an IDE drive by pretending that it’s an A...
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Repurposing Old AMD APUs For AI Work

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The BC250 is what AMD calls an APU, or Accelerated Processing Unit. It combines a GPU and CPU into a single unit, and was originally built to serve as the heart of certain Samsung rack mount servers. If you know where to find cheap surplus units of the BC250, you can put them to good use for AI work , as [akandr] demonstrates. The first thing you’ll have to figure out is how to take an individual BC250 APU and get it up and running. It’s effectively a full system-on-chip, combining a Zen 2 CPU with a Cyan Skillfish RDNA 1.5 GPU. However, it was originally intended to run inside a rackmount server unit rather than a standalone machine. To get it going, you’ll need to hook it up with power and some kind of cooling solution. From there, it’s a matter of software. [akandr] explains how to get AI workflows running on the BC250 using Ollama and Vulkan, while noting useful hacks to improve performance like disabling the GUI and tweaking the CPU governor. The hardware can be used with a wid...
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