Born To Burn: The Battle Born LFP Battery

December 25, 2025 by Maya Posch 37 Comments

Would you feel confident in buying US-made LiFePO₄ (LFP) batteries? While the answer here is generally expected to be ‘yes’, especially compared to getting an unbranded LFP battery off eBay from a random seller, the outcome may not be that different. Case in point the 100 Ah, 12 VDC LFP Battle Born battery that [Will Prowse] took a look at to see why its positive terminal gets positively crispy.

Battle Born battery positive terminal. (Credit: Will Prowse, YouTube)

Once the lid was cut off, it’s easy to see what the problem is: the positive terminal is only loosely attached to the bus bar, leading to extremely poor contact. It also appears that there’s a plastic spacer which has properly melted already in this well-used battery that [Will] obtained from a viewer.

This overheating issue with Battle Born batteries has been reported for years now, which makes it a great idea to take a good look at any Battle Born LFP batteries you may have kicking around, as they may be plagued by the same design flaw. Trying to make use of the manufacturer’s warranty could be complicated based on the commentators in the DIY Solar Forum thread, as Battle Born likes to claim that the overheating issue is an external problem and not a design flaw.

Either way, it looks like an incredibly sketchy way to design a battery terminal on an LFP battery that is supposed to surge 100+A. [Will] is requesting that anyone affected posts details in the forum or similar to get all information together, as he looks to push Battle Born on this issue.

What makes this issue worse is that shortly after releasing that first video, Battle Born responded to some concerned customers with a response that claims that their terminal design is a ‘thermal fail-safe’, but as can be seen in [Will]’s follow-up video, it absolutely doesn’t look like one.

Continue reading “Born To Burn: The Battle Born LFP Battery” →

Twelve Days Of Christmas As Performed By 1980s Speech Chip

December 25, 2025 by Tyler August 5 Comments

In a curious historical twist, the “Twelve days of Christmas” are actually the days of revelry that followed the 25th. The preceding period, Advent, was traditionally a fast, not unlike Lent. When and why a fast became an excuse for chocolate calendars we cannot say, but this historical information is presented to explain that this great hack by [Kevin], making a vintage speech synthesizer chip sing the classic carol will remain relevant at least until January 5th — or perhaps even the 19th, for the Orthodox amongst us.

The chip in question is an SP0256A-AL2, which you may remember from various speech projects for 8-bit computers back in the day. It can talk, after a fashion, by reproducing 56 “allophones” — the sounds that make up English speech — from ROM. Singing, though? We cannot recall much of that back in the day, but then, a talking computer was impressive enough.

As it turns out this is building on an earlier hack [Kevin] did in which he used an Arduino to make the venerable speech chip MIDI controllable. In that project’s write-up it is revealed that a Si5351 programmable clock module is used to give a variable pitch signal to the speech synthesizer. In this way he’s able to get about an octave an a half, which is good enough when the carol in question only spans one octave.

Of course the pitch signal needs to be varied by something and for that the venerable Arduino once again takes the place of an 8-bit computer. In this case it’s pre-programmed, but can also be set up for MIDI control.Of course nothing says you can’t use true retro hardware or a more-capable RP2040 instead of the Amtel chip.

It’s sad to think how much compute power has been wasted this year on AI-generated novelty carols when a little bit of 1980s silicon and some ingenuity can do nearly as good — or better, depending on your tastes. Continue reading “Twelve Days Of Christmas As Performed By 1980s Speech Chip” →

Building A High-Performance Shifter For Sim Racing

December 25, 2025 by Lewin Day 8 Comments

These days, sim racing is more realistic than ever. There are better screens, better headsets, and better steering wheels with better force-feedback, all of which help make you feel like you’re driving the real thing. If you’re looking for a stick shifter to complete such a setup, [DAZ Projects] might have just what you’re looking for.

To create a robust shifter with great feel, the build relies on 3D printed parts as well as lots of quality metal hardware. At the heart of the build is a linear rail for the front-to-back movement, with a printed slider on top with a carefully-profiled indexer to ensure the stick properly ca-chunks into the right gear. A ball joint locates the shift lever itself, while allowing for smooth movement left-to-right. Centering is via simple extension springs. The H-pattern shift is enforced with machined steel rods. Detecting the position of the stick is handled via microswitches, with an Arduino Leonardo reading the switches and reporting itself as a USB device that should work with any modern sim.

It’s funny to think that such a mechanism would once have been a very serious machining job. These days, you can just squirt all this stuff out on a printer in a few hours. For the parts that can’t be extruded, [DAZ Projects] has provided a parts list on Google Docs.

We’ve featured some great racing sim builds over the years, from button pads to pedal boxes.

Continue reading “Building A High-Performance Shifter For Sim Racing” →

Printing With Metal On The Ender 3 Using Only A Friction Wheel

December 24, 2025 by Maya Posch 9 Comments

Printing metal as easily as it is to print with thermoplastics has been a dream for a very long time, with options for hobbyists being very scarce. This is something which [Rotoforge] seeks to change, using little more than an old Ender 3 FDM printer and some ingenuity. Best of all is that the approach on which they have been working for the past year does not require high temperature, molten metals and no fussing about with powdered metal.

Additive manufacturing using friction welding. (Credit: Ruishan Xie, et al., j.mtcomm, 2021)

Rather than an extruder that melts a thermoplastic filament, their setup uses metal wire that is fed into a friction welding tool head, the details of which are covered in the video as well as on the GitHub project page. Unlike their previous setup which we reported on last year, this new setup is both safer and much riskier. While there’s no more molten metal, instead a very loud and very fast spinning disk is used to provide the friction required for friction welding, specifically friction and rolling-based additive manufacturing (FRAM) as in the cited 2021 paper by [Ruishan Xie] et al. in Materials Today Communications. By the same lead author there’s also a 2025 paper that explores more complex implementations of FRAM.

Continue reading “Printing With Metal On The Ender 3 Using Only A Friction Wheel” →

Mesh “Lens” Lets Your Camera Make Weird Pixel Art

December 24, 2025 by Lewin Day 14 Comments

We seldom talk about 3D printing lenses because most techniques can’t possibly produce transparent parts of optical quality. However, you can 3D print something like a lens, as [Luke Edwin] demonstrates, and get all kinds of crazy pictures out of it.

[Luke’s] lens isn’t really a lens, per se. There’s no transparent optical medium being used to bend light, here. Instead, he’s printed a very fine grid in a cylindrical form factor, stuck it on a lens mount, and put that on the front of a camera.

The result is effectively a set of parallel tubes that guide light on to the camera’s image sensor. With the lack of any sort of focus mechanism, you can’t use this “lens” to photograph anything more than a few centimeters away. Get something up close, though, and you can take very simple, very grainy images that are reminiscent of classic pixel art. [Luke] demonstrates this in some fun ways, using it to take photographs of money, a plant, and his own eye. The images look almost like art assets straight out of a 16-bit game. He’s got the STL file up for sale if you want to print your own at home.

We’d love to see this concept explored further, maybe with some supporting optics for more versatile use. In the meantime, you might explore other ways of using 3D printers for photographic gain.

Continue reading “Mesh “Lens” Lets Your Camera Make Weird Pixel Art” →

Abusing X86 SIMD Instructions To Optimize PlayStation 3 Emulation

December 24, 2025 by Maya Posch 5 Comments

Key to efficient hardware emulation is an efficient mapping to the underlying CPU’s opcodes. Here one is free to target opcodes that may or may not have been imagined for that particular use. For emulators like the RPCS3 PlayStation 3 emulator this has led to some interesting mappings, as detailed in a video by [Whatcookie].

It’s important to remember here that the Cell processor in the PlayStation 3 is a bit of an odd duck, using a single regular PowerPC core (PPE) along with multiple much more simple co-processors called synergistic processing elements (SPEs) all connected with a high-speed bus. A lot of the focus with Cell was on floating point vector – i.e. SIMD – processing, which is part of why for a while the PlayStation 3 was not going to have a dedicated GPU.

As a result, it makes perfect sense to do creative mapping between the Cell’s SIMD instructions and those of e.g. SSE and AVX, even if Intel removing AVX-512 for a while caused major headaches. Fortunately some of those reappeared in AVX2.

The video goes through a whole range of Cell-specific instructions, how they work, and what x86 SIMD instructions they were mapped to and why. The SUBD instruction for example is mapped to VPDPBUSD as well as VDBPSADBW in AVX-512, the latter of which mostly targets things like video encoding. In the end it’s the result that matters, even if it also shows why the Cell processor was so interesting for high-performance compute clusters back in the day.

Continue reading “Abusing X86 SIMD Instructions To Optimize PlayStation 3 Emulation” →

Disposable Camera Viewfinder Becomes 3D Printed Lens

December 24, 2025 by Lewin Day 8 Comments

Disposable cameras are a fun way to get into classical photography. However, they can also be a valuable source of interesting parts that can be put to other uses. For example, as [Billt] demonstrates, their viewfinders can be repurposed into a rather interesting lens for more serious cameras.

[Billt] was lucky enough to score a grabbag of used disposable cameras from a local film lab, and tore them down for parts. He was particularly interested in the viewfinders, since Kodak equipped its disposable cameras with actual plastic lenses for this very purpose.

[Billt] wanted to see what these lenses would do when thrown on the front of a proper digital camera, and set about designing a mount for that purpose. The 3D printed part was designed to mount one of the viewfinder lens assemblies on the front of any Sony E-mount camera. In a rather nifty trick, [Billt] realized the lens assembly could be installed in the adapter by pausing mid-way through the 3D print to drop it in. The only unfortunate thing? The lenses didn’t really work, and all the camera could see was a haze of unfocused light.

With the aid of some cardboard experiments, [Billt] decided to make some changes. The front element of the viewfinder was dumped, with the rear element being used solo instead. This was fitted to the adapter on a simple slide mechanism so that focus could be reliably adjusted. With these changes, the lens came good, and provided some really interesting shots. It’s quite a cropped lens and it can achieve a very close focus distance, as little as 1 inch in testing. It’s quite sharp in the center of the image, while softly blurring out towards the edges—something that sounds very familiar if you’ve used one of these disposable cameras in the wild.

Sometimes it’s fun to grab a random piece of junk to see if you can turn it into something good. Video after the break.

Continue reading “Disposable Camera Viewfinder Becomes 3D Printed Lens” →