A clear plastic block is shown on a workbench. The plastic block has channels running through it, with liquid flowing through the channels. A pressure gauge is mounted to the top of the block, and an alcohol burner is placed near the base.

3D Printed Einstein-Szilard Refrigerator Cools With Fire

October 31, 2026 by Aaron Beckendorf 2 Comments

They may not deliver the highest efficiency, but absorption refrigerators have earned a persistent place in camper vans and industrial plants thanks to a few distinct advantages: they can operate using waste heat alone as an energy source, and they can be quite reliable due to their lack of moving parts. It can be a bit hard to understand their working principles, though, which is why [Ben Krasnow] built a transparent Einstein-Szilard refrigerator.

Most absorption refrigerators use ammonia and water as their working fluids; since the ammonia gas needs to condense at room temperature, the refrigerator requires pressures above what can be comfortably held in a glass or plastic enclosure. The Einstein-Szilard design, by contrast, uses a third liquid as its refrigerant. A strong solution of ammonia in water is separated by boiling, and the ammonia gas induces the refrigerant to evaporate by decreasing its partial pressure. The refrigerant and ammonia gasses then mix with water, in which the ammonia dissolves, leaving the refrigerant vapor to condense and start the cycle again. The newly reformed water-ammonia solution flows back into the boiler.

The refrigerant is usually butane, but since [Ben] was powering this pressurized system with an open flame, he opted instead for nonflammable perfluoropentane. The refrigerator body itself was 3D printed in clear resin, with a copper block transferring heat from the flame to the boiler chamber; ammonia solutions do dissolve copper, so this isn’t a long-term solution, but it works for a demonstration. The single internal path of the refrigerator presented some difficulties: since almost no pressure builds up between different parts of the system, a bubble in the wrong place can easily airlock it. In the end, [Ben] managed to get it working well enough to reach five degrees Celsius below the ambient temperature. Conveniently, he notes that, for alcohol at a sufficiently high concentration, you could cool your drink by burning a portion of it.

Ammonia-based refrigerators are a tough build for most hackers, but we have seen a salt-water-based absorption refrigerator before. For more less-known refrigerators, check out our article on strange cooling methods.

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Novelty Camera To USB Camera

October 30, 2026 by Jenny List No comments

The Godox C100 is a cheap camera that’s best described as a toy, its party trick being a large clear viewfinder with a head-up-display light meter. It’s by no means a high quality device, being little more than a dashcam in a fancy case, but like many others of its kind it offers opportunity for the camera hacker. [Holofermes] has one, and has given it a suite of patches that, among other things, convert it to a USB webcam and give it a Pi Zero dock.

It takes the standard firmware and adds the patches on top, so while they’re installed it can only act as USB drive and webcam, if a return to camera is desired then the original firmware must be flashed. There are some details on the hardware, such as that ti runs FreeRTOS on an Arm architecture with 16 megabytes of memory. The sensor has a 1920 by 1080 pixel resolution, which is a step up from the upscaled VGA of may such cameras.

Many novelty cameras are not as hackable as this one, which makes it interesting. We hope that more camera hackers will turn their attention to it. It’s not the first cheap camera we’ve taken a look at.

VR Headset Ditches The Base Stations With DIY Tracking

October 30, 2026 by Donald Papp No comments

Those in the virtual reality scene might be interested in [Prohurtz]’s add-on for the Bigscreen Beyond VR headset. BSB-SLAM adds SLAM (Simultaneous Localization and Mapping) tracking to the headset by attaching a sensor to the front of the headset, and providing the software to tie the two together. As a result, the headset can be fully tracked in 3D space with no need for external base stations. It essentially adds inside-out tracking as a DIY add-on.

An early version, shared with a brief video demo posted to X.

Just to be clear, that doesn’t mean the headset becomes wireless. The Beyond connects to a PC, essentially acting as a display, and that part is the same. But it does mean the headset is no longer tied to having to work in a room with base stations pre-installed.

[Prohurtz]’s solution does this by adding a small off-the-shelf Xvisio XR50 board, USB cable, and 3D-printed mount to the unit. The headset works as normal, just with some extra software needed to use the sensor data in lieu of the base stations.

As far as sensors go the Xvisio XR50 is a bit spendy, but the fact that a small and lightweight SLAM sensor that’s capable of delivering positioning data suitable for tracking a headset in near real-time can be bought online and so readily adapted is pretty interesting.

[Prohurtz] got the idea working back in 2025 but it’s now at the point where one can order a part, print an adapter, and be off to the races with a software package.

This isn’t [Prohurtz]’s first time with VR hardware, either. The EyeTrackVR eye tracking add-on is also their work, combining largely off-the-shelf hardware into an effective DIY solution for VR use.

A 1982 Modem For $100

October 30, 2026 by Al Williams 11 Comments

[Dave Farquhar] takes a walk down memory lane about the Commodore 1600 VICModem, perhaps the first phone modem to sell for less than $100. Commodore, of course, was famous for making cheaper computers like the VIC20, the Commodore 64, and lower-cost peripherals like disk drives. But how did they hit the $100 price point with the modem when competing 300 baud modems sold for at least twice that, and a 1200 baud unit would set you back at least $600?

First, Commodore didn’t handle the design themselves. Instead, they outsourced to Anchor Automation, a well-known modem manufacturer. It used a Motorola MC14412 modem on a chip, along with six other chips. The chip could, in theory, do 600 baud, but the modem was rated for 300. But it did make some interesting design choices.

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Making Internal Combustion Engines Better With More Valves

October 30, 2026 by Maya Posch 14 Comments

When it comes to internal combustion engines (ICEs), it’s generally accepted that each cylinder doesn’t have more valves to let in a fresh fuel mixture and to exhaust the aftermath than absolutely necessary. You could argue in favor of this also because it reduces the amount of valve seat surface and thus the potential for leaks, but there is historical precedent for higher valve counts. Hence [Alexander’s Laboratory] had to give a ten-valve engine a shake, just to see what effect adding more valves has.

A cited historical example is the Yamaha FX750, which features a four-cylinder engine that has three inlet and two outlet valves per cylinder, making for a 20-valve design that is claimed to improve performance, also because each valve can be smaller and lighter than with a single valve per side. Other motorbike manufacturers would also try such configurations, with some fascinating examples shown in the video.

What [Alexander] tries here is to create a 10-valve version, for a symmetric five valves intake and five for exhaust. Rather than building an entire engine from scratch, the largely 3D-printed ICE that was featured in previous videos will be modified with a new cylinder head, replacing the current four-valve one.

For the custom valves large wood screws are used, after making sure that they can take the heat of the combustion. Making even ten of these small valves fit was a challenge, but ultimately got squeezed into a CNCed aluminium and nylon-printed hybrid cylinder head. The existing camshaft was reused by using an adapter that simply drives five valves at the same time.

After some troubleshooting and tuning the engine actually runs pretty well, though sadly no comparison metrics were provided versus the four-valve version of the cylinder head. Hopefully we’ll see this in an upcoming video.

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A Modern Smalltalk

October 30, 2026 by Al Williams 3 Comments

In the history of object-oriented (OO) computer languages, Smalltalk has a special place. It wasn’t the first OO language, and it hasn’t spread as well as some others. But it was the first OO language many people encountered, and it influenced many other languages you’ve probably seen. Developed at the famed Xerox PARC, it also introduced many people to the “model/view/controller” (MVC) architecture. Cuis Smalltalk is a free and portable modern Smalltalk-80 environment. It replaces the traditional MVC framework with Morphic, but otherwise, it would be very familiar to someone who used Smalltalk in the 1990s. The project’s goal is to stay simple at the core, although you can add complexity via packages.

The software has been around for a while, but it is on a rolling release model, so the install page suggests you clone the Git repo. You can, however, get a stable release, which might be important if you were deploying applications. Running the program results in a Cuis desktop where you can open various things like workspaces, help documents, and the transcript.

Smalltalk throws some people because it takes OO to an extreme. For example, you don’t add two and three using an operator. You send the object two a message that includes another object, three. You can think of sending a message as calling a method on an object. As with virtual functions in C++, different objects can respond differently to the same request. For example, an Animal class might have a speak message that causes a cow to print “moo” and a chicken to print “cluck.”

You get used to it, and there’s a very nice class browser that lets you examine classes and what you can do with them. There are even packages to work with an Arduino over a serial port. They haven’t been updated lately, so they might (or might not) need a little work.

We’ve looked at GNU Smalltalk before. We’ve also seen a version that runs directly on a Raspberry Pi.

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Hackaday Podcast Episode 393: Epaper, Tamagotchi Hacks, And Supercon Talks Galore

October 30, 2026 by Jenny List No comments

This week’s podcast comes from Europe, as Elliot Williams is joined by Jenny List, who wishes to apologies for the poor sound quality from her headset microphone. The news this week is our Supercon conference which is upcoming, we’ve released more speaker details.

We start the hacks with a follow-up to an exciting development. We’ve seen e-paper screens driven at high frame rates, but do the techniques used shorten the life of these displays? Then we have Tamagotchi hacking, re-using an old mobile phone as a flight controller, the oldest Windows app to run on Windows 11, and probably the prettiest mini TV studio rack you will ever see. Pushing Bluetooth out to 12 kilometres is the cherry on the cake.

In quick hacks there’s a swash plate-less helicopter, Commodore 64 keycaps, and the history of the mouse, before our can’t-miss look at infra-red transmission, and a forgotten Google VR headset.

Check out the links if you want to follow along, and as always, tell us what you think about this episode in the comments, or drop us a line on the mailbag.

Download yourself a little podcast, won’t you?