Electric Truck Sets Racing Record

April 13, 2026 by Bryan Cockfield 15 Comments

The 24 Hours of Le Mans races is an extremely prestigious endurance motorsport event which attracts the best cars and drivers from around the world. It’s one of the longest-running races too, taking place once a year since 1923 (with a few obvious understandable gaps). But, like most motorsports, it’s financially out of reach for most people. One of the more popular attempts to bring racing to the masses has been the 24 Hours of Lemons races, which have price limits on vehicles to keep the barrier to entry low, and an EV truck recently entered one of these races with some interesting results.

The group behind this vehicle is called Team Arcblast, who retrofitted an old Datsun pickup truck to the extreme to enter this race. The modestly sized electric motor is installed in between the cab and the bed for easy access to the driveshaft, with the engine bay repurposed for all of the cooling and radiators needed for endurance racing like this. They’ve also equipped the truck with plenty of efficiency-increasing spoilers and other aerodynamic parts, and rebuilt the cab with not only the required roll cage and other safety equipment, but a modified driving position with steering and other components from various Miatas.

The most impressive part of this build, however, is the battery. The team invented a method of swapping out batteries quickly to avoid having to fast charge the car in the pit area. The system lets a battery slide in to the middle of the truck above the motor and quickly connect to the electrical system allowing for very quick pit stops and the ability to charge other batteries while the race goes on. All of these modifications together allowed the team to break the EV record for a Lemons race.

For a Lemons race, though, even this truck stretches the original spirit that these races were started, however impressive the build. We published a primer to these types of races a while back which includes much more affordable internal combustion options.

Thanks to [JohnU] for the tip!

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2001: An Air Quality Odyssey

April 8, 2026 by Bryan Cockfield 6 Comments

2001: A Space Odyssey not only pushed the boundaries of filmmaking, but introduced us to one of the most enduring villains in all of media. The HAL 9000 artificial intelligence was human-like but inhuman, a singular uncanny red light on a wall, tasked not only with control of a spaceship and its inner workings but also with being a companion for its occupants. It’s gone on to be the inspiration and basis of many projects around here, where it is generally given much less scope than control of a space ship and instead is tasked with something like monitoring air quality in a home.

Called the PAL 8000 by its creator [Arnov], this uses a Raspberry Pi Pico 2 at its core which monitors a volatile organic compound (VOC) sensor to take air quality measurements. The device features a custom 3D printed enclosure with glowing LEDs and plays contextual audio responses based on air quality levels, completing the HAL 9000 theme. The project also includes a local web dashboard which reports on its data, allowing users to see information in real time rather than relying on HAL’s voice reports alone.

For those looking to build other HAL-inspired projects, [Arnov] has made many of the printing files available on the project’s site. It’s a well-polished build faithful to the source material and could be a great addition to any home automation system for many other tasks beyond air quality monitoring. Perhaps something like a more general-purpose voice assistant, minus the megalomania.

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Chicken Coop Door Performs In Harsh Environment

April 3, 2026 by Bryan Cockfield 22 Comments

One of the pitfalls of modern engineering is that it’s entirely possible to end up in a situation where a product or solution has been designed by someone who has never left a desk. Which wouldn’t be a problem if things didn’t have a tendency to work differently in real life than they do in theory.

One of those things is automatic chicken coop doors, which have to operate reliably in not only a wide range of climates but with a number of possible physical limitations as well. [Vinnie] has taken on the challenge of building one which actually accomplishes all of these tasks, after realizing that the off-the-shelf solutions were victims of design over practicality.

[Vinnie] designed this door to be operated by the one thing that’s always 100% reliable: gravity. A linear actuator lifts the door at the beginning of the day, and then at night it’s allowed to fall back down in its track. A latch secures it against smarter intruders like raccoons. [Vinnie] has found that this lifting mechanism holds up much better in mud, snow, ice, and other difficult conditions than any other method he’s tried so far.

The system is built around a ATmega1284P, and calculates the sunrise and sunset times each day to know when to open or close the door. He’s built the system as a state machine which makes it more robust during power outages, which is a necessity since his chicken coop is mobile and is frequently out of range of WiFi and is battery powered.

The approach [Vinnie] takes to automation is something that has application outside of his own farmstead. Using state machines instead of schedules, ensuring the design is as simple as possible and works within its environment, and minimizing reliance on electric and data infrastructure can go a long way to solving problems that might not appear when designing something on paper.

He’s been automating many other things on his farm as well, and it’s worth checking it out if you haven’t seen it already.

Battery Tester Outperforms Cheaper Options

April 1, 2026 by Bryan Cockfield 4 Comments

Batteries are notoriously difficult pieces of technology to deal with reliably. They often need specific temperatures, charge rates, can’t tolerate physical shocks or damage, and can fail catastrophically if all of their finicky needs aren’t met. And, adding insult to injury, for many chemistries, the voltage does not correlate to state of charge in meaningful ways. Battery testers take many efforts to mitigate these challenges, but often miss the mark for those who need high fidelity in their measurements. For that reason, [LiamTronix] built their own.

The main problem with the cheaper battery testers, at least for [LiamTronix]’s use cases, is that he has plenty of batteries that are too large to practically test on the low-current devices, or which have internal battery management systems (BMS) which can’t connect to these testers. The first circuit he built to help solve these issues is based on a shunt resistor, which lets a smaller IC chip monitor a much larger current by looking at voltage drop across a resistor with a small resistance value. The Pi uses a Python script which monitors the current draw over the course of the test and outputs the result on a handy graph.

This circuit worked well enough for smaller batteries, but for his larger batteries like the 72V one he built for his electric tractor, these methods could draw far too much power to be safe. So from there he built a much more robust circuit which uses four MOSFETs as part of four constant current sources to sink and measure the current from the battery. A Pi Zero monitors the voltage and current from the battery, and also turns on some fans pointed at the MOSFETs’ heat sink to keep them from overheating. The system can be configured to work for different batteries and different current draw rates, making it much more capable than anything off the shelf.

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A Better Jogging Stroller

April 1, 2026 by Bryan Cockfield 13 Comments

Although the jogging stroller is a fixture of suburban life, allowing parents the opportunity to get some exercise while letting their young children a chance for some fresh air, it would seem like the designers of these strollers have never actually gone for a jog. Requiring a runner to hold their hands at fixed positions can be incredibly uncomfortable and disrupts most people’s strides and cadence — so [John] attempted to solve the problem after finding one of these strollers on the secondhand market.

While there are some purpose-built strollers that attempt to address these issues, they can be pricey. Rather than shell out for a top-dollar model, [John] got to work with his 3D printer and created a prototype device that allows him to attach the stroller at his waist while leaving his hands free. There were a few problems to overcome here, the first of which would cause the device to buckle under certain loading situations. This was solved with some small pieces of rope which act as flexible bump stops, keeping the hinge mechanism from binding up. Another needed to be solved with practice, which was that it took some time to be able to steer the stroller without using one’s hands.

As an added bonus, [John] also included a system that tracks the distance the stroller has traveled. Using a hall effect sensor and a magnet attached to the wheel, a small microcontroller is able to quickly calculate distance and display it on a tiny screen mounted near the handlebars. Although smartphones are handy, their GPS systems can be surprisingly inaccurate, so a system like this can be a better indicator since it’s being directly measured. All in all, not a bad few upgrades to a secondhand stroller.

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Recreating One Of The First Hackintoshes

March 30, 2026 by Bryan Cockfield 22 Comments

Apple’s Intel era was a boon for many, especially for software developers who were able to bring their software to the platform much more easily than in the PowerPC era. Macs at the time were even able to run Windows fairly easily, which was unheard of. A niche benefit to few was that it made it much easier to build Hackintosh-style computers, which were built from hardware not explicitly sanctioned by Apple but could be tricked into running OSX nonetheless. Although the Hackintosh scene exploded during this era, it actually goes back much farther and [This Does Not Compute] has put together one of the earliest examples going all the way back to the 1980s.

The build began with a Macintosh SE which had the original motherboard swapped out for one with a CPU accelerator card installed. This left the original motherboard free, and rather than accumulate spare parts [This Does Not Compute] decided to use it to investigate the Hackintosh scene of the late 80s. There were a few publications put out at the time that documented how to get this done, so following those as guides he got to work. The only original Apple part needed for this era was a motherboard, which at the time could be found used for a bargain price. The rest of the parts could be made from PC components, which can also be found for lower prices than most Mac hardware. The cases at the time would be literally hacked together as well, but in the end a working Mac would come out of the process at a very reasonable cost.

[This Does Not Compute]’s case isn’t scrounged from 80s parts bins, though. He’s using a special beige filament to print a case with the appropriate color aesthetic for a computer of this era. There are also some modern parts that make this style computer a little easier to use in today’s world like a card that lets the Mac output a VGA signal, an SD card reader, and a much less clunky power supply than the original would have had. He’s using an original floppy disk drive though, so not everything needs to be modernized. But, with these classic Macintosh computers, modernization can go to whatever extreme suits your needs.

Thanks to [Stephen] for the tip!

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Training A Transformer With 1970s-era Technology

March 29, 2026 by Bryan Cockfield 15 Comments

Although generative language models have found little widespread, profitable adoption outside of putting artists out of work and giving tech companies an easy scapegoat for cutting staff, their their underlying technology remains a fascinating area of study. Stepping back to the more innocent time of the late 2010s, before the cultural backlash, we could examine these models in their early stages. Or, we could see how even older technology processes these types of machine learning algorithms in order to understand more about their fundamentals. [Damien Boureille] has put a 60s-era IBM as well as a PDP-11 to work training a transformer algorithm in order to take a closer look at it.

For such old hardware, the task [Damien Boureille] is training his transformer to do is to reverse a list of digits. This is a trivial problem for something like a Python program but much more difficult for a transformer. The model relies solely on self-attention and a residual connection. To fit within the 32KB memory limit of the PDP-11, it employs fixed-point arithmetic and lookup tables to replace computationally expensive functions. Training is optimized with hand-tuned learning rates and stochastic gradient descent, achieving 100% accuracy in 350 steps. In the real world, this means that he was able to get the training time down from hours or days to around five minutes.

Not only does a project like this help understand these tools, but it also goes a long way towards demonstrating that not every task needs a gigawatt datacenter to be useful. In fact, we’ve seen plenty of large language models and other generative AI running on computers no more powerful than an ESP32 or, if you need slightly more computing power, on consumer-grade PCs with or without GPUs.