Reverse Engineering And Self-Hosting The OBI Smart Energy Tracker

July 7, 2026 by Maya Posch 8 Comments

Sold by German DIY store OBI, the OBI Energy Tracker is a €15 set of two devices, one of which you essentially stick on top of your existing electricity meter. This then allows for electricity usage to be measured and tracked, with the data sent to the second, gateway device. This latter cloud-bound device is linked to an OBI account via the heyOBI app. This correspondingly called for the gateway device to be reverse-engineered and freed from its cloud-based shackles, a task that [Aaron Christophel] happily took upon himself.

The whole process is also covered in two videos, with the first providing all the essentials on reprovisioning the original firmware for a local MQTT server in English, while the second, German-language video focuses on custom firmware for the ESP32-C3 inside of the gateway device.

Inside the reader device is a Cortex-M0+-based BAT32G135 MCU that communicates with the meter via its IR protocol. This is then communicated via 868 MHz LoRa to the gateway device that will be placed somewhere within Wi-Fi reach by the user. Inside this latter device is as mentioned the ESP32-C3, which by default runs firmware that communicates via secure MQTT with an AWS cloud instance for the typical cloud-based shenanigans.

The aforementioned reprovisioning option doesn’t require firmware flashing, just a handful of steps to follow. This involves fetching the 32-bit TEA key, generating your own PKI, running your own MQTTS-capable broker and having the provided Python script handle the rest from there.

Flashing custom firmware is the other option, with straightforward UART/JTAG reflashing sadly disabled by the manufacturer. With the effort required here you could perhaps argue that simply connecting the reader device to a custom gateway device might be a lot easier, especially if you already have a LoRa transceiver and associated hardware.

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How To Rebuild An 1800s Victorian Leclanché Cell

July 6, 2026 by Maya Posch 20 Comments

The 19th century was an absolutely electrifying era, including in a literal sense. Although the phenomenon of electricity had been known by that time for centuries, actually making it do useful work was a much taller order. Aside from big, coal-powered generators, there also was a need for a more compact electrochemical solution, such as in the form of a wet or dry cell. One of the first major commercial successes here came in the form of the Leclanché cell, such as the genuine version that [Big Clive] found in an old UK building’s attic and has now revived.

Invented in 1866 by French scientist Georges Leclanché, the Leclanché cell features an ammonium chloride electrolyte solution, carbon cathode and zinc anode. There’s also a manganese dioxide depolarizer for preventing hydrogen build-up. Here water is the solvent for the ammonium chloride (also known as sal ammoniac).

The version that [Clive] got his grubby mitts on features a glass container, an already partially consumed zinc electrode and a slightly cracked porous ceramic tub that contains the carbon electrode and the manganese dioxide. After placing the components inside the specially shaped glass jar and filling it with an electrolyte mixture of one part ammonium chloride and four parts water by weight, the cell starts generating its approximate 1.4 VDC.

This type of wet cell was very popular, being essentially ‘rechargeable’ by topping up the water and replacing the zinc electrode consumable. They did suffer from a voltage drop-off during use due to increasing internal resistance, something that got improved upon with the zinc-carbon dry cell. Itself effectively an evolution of the Leclanché wet cell.

From there zinc-carbon dry cells got replaced with alkalines, which itself got mostly replaced by NiMH and Li-ion cells. Despite more than a hundred years between the electrochemical cell that [Clive] featured in his video and today’s batteries, it’s clear that this wet cell was quite literally just the Victorian-era equivalent of an alkaline AA cell.

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Gluing 8192 MCUs Together To Make A GPU

July 6, 2026 by Maya Posch 25 Comments

What do you get when you take 8,192 CH570 MCUs, put them on custom PCBs, and write firmware for this interconnected gaggle of cores? In the case of [bitluni]’s project, you get something that’s decidedly cluster-shaped.

These cheap MCUs feature a QingKe 32-bit RISC-V core that’s clocked at a maximum of 100 MHz, with an RV32IMBC instruction set. This means that they support integers, integer multiplication and division, bit manipulation, and compressed instructions, but no atomic, vector, or floating-point instructions.

The basic concept was to use a single MCU per pixel, but once you start scaling up a measly 10 mA and ~$0.10 per MCU to literally tens of thousands of them, you’re suddenly talking about thousands of dollars in hardware as well as a cool 655.36A at 3.3V – or 2 kW – for something close to QVGA resolution at 320×200. Clearly this would be a rather crazy project to implement, which is why each MCU also got its own RGB LED to immediately create the pixel.

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Demonstrating LFP Battery Safety In Case Of BMS Failure

July 5, 2026 by Maya Posch 24 Comments

Generally, LiFePO₄ (LFP) batteries are quite safe and stable, but it’s still possible for something to go wrong, even something catastrophic, like the battery management system (BMS) developing a direct short. This is one of the tests required to be certified for the UL 2054 standard that targets household and portable battery safety. In a recent series of videos, [Will Prowse] demonstrates how a series of commercial batteries pass these tests, and how some still fail.

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Using Flatpak To Run A 1996 Version Of The GIMP On Modern Linux

July 4, 2026 by Maya Posch 4 Comments

Although there’s probably no good reason to want to run image editing software from 1996 other than for nostalgia’s sake, if you ever wanted to run the GIMP version 0.54 from back when Windows 98 was still called Windows 97, you can do so now from the comfort of a modern-day Linux desktop. What enables this is a Flatpak version of a beta release, assembled by [balooii] for everyone’s enjoyment.

It wasn’t a simple matter of compiling the old software’s code and packaging it up, with the repository for the project containing a series of patches that were required to make this possible. Also of note is that this is the first version of GIMP with full surviving source code. Back then, GIMP used the Motif widget toolkit. Later on, it switched to the GIMP Toolkit (GTK).

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Warp Point: A Web Ring For Gaming Sites Built For 2026

July 4, 2026 by Maya Posch 6 Comments

At one point in time web rings were one of the best ways to find content on the World Wide Web — involving not just a directory of participating sites, but also each site linking to each other in a ring-like fashion. With search results these days becoming increasingly less useful, having such a focused resource sounds better and better, with the Warp Point directory and web ring now doing just that for video game websites. Topics range from reviews to retro gaming and game development, so there’s probably something for everyone here.

For the reasoning behind this effort take a look at this article by [Wes Fenlon] and [Matt Sayer]. The inspiration was part nostalgia and part longing for the return of a simple system that Just Works™ without algorithms, advertising, ‘AI’ and corporate overlords involved at any point in time. Everything is just focused on helping you find the content and community you were looking for as quickly as possible, though spending a few hours just clicking through the ring is also perfectly fine.

Everyone is free to submit their own awesome site to Warp Point, after which it’ll be manually reviewed. Even if not strictly curated, it would seem to be a refreshing return to a more simpler time, using an approach that should still hold up just as well as it did in 1999.

Although the big commercial web directories like those on Yahoo! quickly became unwieldy and unusable, there’s a lot to be said for having these small, focused web directories and rings to regain that sense of community and humanity that’s become so scarce on the WWW in 2026.

Settling The Debate On Soldered Versus Crimped High-Current Connectors

July 3, 2026 by Maya Posch 84 Comments

For some reason there’s heated debate around the topic of whether high current carrying wiring ought to use crimped or soldered connections, even though the industry standard is to crimp everything. As a practical demonstration of why this is the case, [Will Prowse] set up a test involving a rig capable of dispensing a few hundred amps through both a crimped and a soldered copper cable.

Prior to making things go spicy, [Will] made sure to check the resistance of the two cables, noting that the soldered version had significantly lower resistance than the crimped connectors. This could be one metric that proponents of soldered connectors can point to as a benefit.

Of course, the main benefit of crimping is that you create a cold weld if crimped properly, which is a sold-state welding process that effectively blends two metal surfaces together. This is also why wire wrap is generally considered to be so very reliable, as it creates a gas-free, solid connection that does not rely on a softer, dissimilar material like solder to hold things together. Of note here is also that the cold weld process tends to continue for a while, so this kind of connection is likely to get better over time.

In the subsequent testing this difference is demonstrated quite well, especially when both cables are subjected to the sort of mechanical abuse that would be expected in an installation, such as vibrations and direct impacts. Here the soldered connections quickly begin to fail, resulting in one soldered connector even unsoldering itself due to heat development. Ultimately cold welding is simply superior over relying on a flimsy and capricious interface of intermetallic compounds.

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