Author: Bryan Cockfield

1896 Articles

Off-Grid Refrigeration Using Fire And Salt

October 18, 2026 by 31 Comments

Refrigeration has been a challenge for humanity since the start. Ancient civilizations in dry climates like Persia and Egypt could use evaporative cooling on a large scale with specialized architecture, and with easy access to electricity modern civilization can cool down almost anything it wants. But whether in a refrigerator or heat pump, the electricity demands can get out of hand quickly, and heat-driven systems often require dangerous or hard-to-get chemicals. But [Greenhill Forge] has crafted a system that creates effective refrigeration with only fire and salt… and a bit of electricity.

Heat-driven systems are called absorption coolers. In this design, water is used as a refrigerant and forced to a very low pressure so that it can boil at a low temperature. When it boils it absorbs heat from the surrounding environment, and then that water vapor can be moved and condensed where it gives off that heat. The build has a few distinct loops to make all of this happen. The generator loop holds the heat source and a tank of water mixed with road salt. Boiled water travels up a tube to a condenser. A valve here is opened slightly to allow the water to drip into the absorber section, where it is under low pressure and boils rapidly. The vapor is carried away by the third system, which uses a shower of the salt solution to quickly suck up the vapor and move it away from the cooled area.

There is a small amount of electricity needed to run pumps and fans, but to keep this off-grid this requirement is easily met by a small solar panel or battery. The bulk of the energy is from the fire which boils the saltwater solution. [Greenhill Forge] added a number of temperature and pressure sensors to monitor and control the system as well, and in his firsts tests the refrigeration system was able to get to about 5° C with an ambient temperature around 16° C. That’s not quite the temperature needed for a refrigerator, but not bad for only salt and fire. [Greenhill Forge] has a number of other ingenious off-grid builds like this sawdust stove and a magnetic induction water heater.

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Pager Converted To Meshtastic Node

October 14, 2026 by 10 Comments

Text messaging has been around on cellular networks en masse for around three decades now. It’s so common that it’s difficult to remember a time without it. Its two-way quick messaging is incredibly useful, but for even simpler communications there’s a one-way system that predates it. Pagers are able to receive simple messages, but outside of hospitals are rarely used nowadays. Eventually some added in two-way communications like this Motorola T900, but they’re still mostly obsolete. That’s why [zindustries87] converted it to operate on the Meshtastic network instead.

To get this pager working, a lot of reverse engineering was needed. There is essentially no documentation on the chips in these devices, so the screen and keyboard both were reverse-engineered to work with other hardware. In this case, [zindustries87] found space for a Heltec V4 with an ESP32-S3, a popular Meshtastic node with a small form factor. Some programming was needed to get everything communicating together, but from the looks of things it seems to have basic functionality.

[zindustries87] points out that this is a prototype, and didn’t know going in if the keyboard and screen could be brought back to life, or if the other hardware would fit in the case. But with it working on this level, they plan to add a number of other features in and possibly build a drop-in PCB replacement for these devices. They were once fairly popular so there are plenty around, and they’re a good form factor for a dedicated Meshtastic device that doesn’t need a smartphone to work. The only other ways of bringing pagers back to life involve bootstrapping an entire pager network, and Meshtastic is a bit more useful than that now.

Single Button, Handheld Gaming Console

October 14, 2026 by 7 Comments

Those of us who grew up in the 70s and 80s might be familiar with the Atari 2600 console and its now relatively unrecognizable (by modern standards) controller with only a single button and stiff whole-hand joystick. By comparison, the Steam Deck has somewhere around 24 buttons and two joysticks depending on how they are counted. But even the Atari might be providing more user inputs than are really necessary for quality gaming. Take a look at the Dinoboy, a handheld console with only a single button.

Part of what makes this system work is that it’s playing the classic dinosaur jumping game first included in Google Chrome which loads when the browser can’t connect to the Internet, and the user’s single input was the space bar. In this case, the handheld has its single button where the user’s thumb naturally rests. The console itself is in two parts, hinged where the button is placed. When unfolded, the top half reveals a wide screen and the bottom half is held by the hand. The screen supports two color formats, a black and white style and another which replicates the dot matrix display of the original Game Boy.

The small handheld console has another trick up its sleeve too. [Paul], the system’s creator, built it as a way to stop doomscrolling so along with having this quick-deploying game on hand, there’s also an NFC tag hidden near the hinge which, when swiped passed a phone, also turns that phone’s airplane mode on. It’s a double-whammy of removing the gamer from the dark patterns and algorithms dominating the mainstream Internet. And, this isn’t [Paul]’s only dinosaur jumper console either. We recently featured a similar (but much larger) build of his housed in a classic arcade-style cabinet.

Super Mario 64 Comes To The Microsoft Zune

October 9, 2026 by 8 Comments

As a portable media player, Microsoft’s Zune simply couldn’t compete with Apple’s juggernaut iPod — the latter essentially becoming the de facto personal media player until smartphones took over. But in 2026 it might be Microsoft that gets the last laugh, as thanks to [rsheldiii] the Zune can now play Super Mario 64.

The software is based on sm64ex, and notably doesn’t include the ROM file necessary to actually run the game. But presuming a legal dump of a cartridge has been done, building and loading it onto a Zune HD is straightforward enough. From there the player is presented with a controller interface on the device’s touchscreen overlaid with the video output from the game. Some interesting things are happening in the background here as well, like using NVIDIA’s Tegra tools to pre-compile shaders so the 2009-era processor can handle the rest of the gameplay.

Although it didn’t enjoy the mainstream success of the iPod, the Zune was actually a pretty solid device, and even though the last of them rolled off the assembly line back in 2012, there’s still a fairly active userbase for it. Modern improvements have added Bluetooth and solid-state drive upgrades for them have been available almost since they were first released.

Two-Component H-shifter For Racing Sims

October 9, 2026 by 1 Comment

Flying and driving simulators can go as far as money will take you, and at some point it might end up being cheaper to buy a plane or race car than to keep adding capabilities to some of the sim rigs we’ve seen. But it can also be a fairly affordable hobby as well, with entry-level components being within reach for many. The price can drop precipitously from there too, provided some parts can be sourced and a 3D printer is made available, and [Jason] is demonstrating one of the lowest-cost H-shifters we’ve seen which only uses two parts at its core.

The two components only cover the electronics for the build, but this gets almost everything needed for the shifter squared away. A joystick like those found inside many game controllers is paired with an Arduino Pro Micro, with a very straightforward wiring configuration between them. These components are paired with a prototype 3D printed case and shift knob which provides the H pattern of choice. From there it’s as simple as uploading some readily-available firmware, which [Jason] also demonstrates, and which has many options for various configurations of shifters.

Although this was just a prototype, it shows was just a few off-the-shelf components and a 3D printer can provide to an affordable driving sim setup. Even then a 3D printer is not always necessary, like this three-pedal setup using extruded aluminum frame as a base. From there, all kinds of other features can be added like force feedback on the steering wheel.

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Lead A Discord Exodus With A Matrix Server

October 8, 2026 by 65 Comments

The Internet, and large groups of people in general, tend to have a remarkably short collective memory. Whether it’s the nature of algorithms or the people themselves to always be chasing the next novelty, maintaining long-term engagement for even relatively small changes can be challenging. Distractions abound, and motivation tends to fade over time. This past spring, Discord’s unpopular decision to force age verification resulted in a brief flash-in-the-pan of outrage that dissipated when they promised to delay its roll-out. Rather than backtrack on unpopular policies, they’ve been slowly boiling the frog with incremental changes towards this same goal in the meantime. One of the options to deal with this is to migrate over to something like a Matrix server, which has a number of benefits over Discord including being open-source and self-hostable.

Unlike Discord, a closed platform subject to the whims of a private company, Matrix is a communications protocol and open standard. Its major server and client implementations are open source, so anyone can build tools around it and integrate it with other systems that also use this protocol. This protocol-vs-platform comparison mirrors email, which is another protocol that isn’t locked down by any one company, and which can easily be used to send messages across various providers. The most commonly used server-side software for Matrix is called Synapse and the most prominent general-purpose clients are the various implementations of Element, and my exploration uses these defaults.

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The Deep Magic Of 3D Graphics Perspective

September 29, 2026 by 8 Comments

Many of us of a certain age will have had their first true, good 3D video game experience with Super Mario 64. Unlike previous 3D games, the camera was an object controllable by the player, rather than a first-person-ony mode or one where the game tries to guess the best placement for the camera. We might take this mechanic for granted today, but 3D was a new technology at the time that took experimentation before settling on the norms we have today. From a programming perspective, 3D graphics can be a bit of a head-scratcher but [Gabriel] shows that perspective and the camera can be as simple as a few lines of math.

When starting out as a programmer, [Gabriel] used various tools that provided a camera somewhat automatically. But after reaching the limits of these types of frameworks, the next step is to learn how that works from scratch. It turns out that it’s a bit of matrix math, with values for foreground and background clipping planes as well as aspect, field of view, and position. This basically replicates a trapezoidal prism which can be thought of as a viewer looking at a scene from the perspective of a camera. To provide the depth effect, the X and Y coordinates are divided by the Z coordinate within this matrix system, making far-away objects smaller and generating the 3D effect.

On [Gabriel]’s site which explains this method, there are a few sliders in several examples that demonstrate how changing values of each of these variables changes the perspective and the object being displayed. For a math lesson it is very interactive and helps intuit these concepts. Cameras aside, the generation of 3D objects has its own unique set of math equations to learn about that are “equally” interesting.