HRV Gets Home Automation Upgrades

October 26, 2025 by 5 Comments

In our modern semi-dystopia, it seems like most companies add automation features to their products to lock them down and get consumers to buy even more proprietary, locked-down components. The few things that are still user-upgradable are getting fewer and farther between, but there are still a few things that can be modified and improved to our own liking like this control panel for a heat recovery ventilator (HRV).

HRVs are systems that exchange fresh, outside air with stale, inside air while passing them both through a heat exchanger to keep from wasting energy. Many systems run continuously but they aren’t always needed, so some automation is beneficial. This upgrade from [vincentmakes] improves the default display for a Zehnder Comfoair Q350 HRV with a color display as well as adding it in to a home automation system, letting a user control fan speeds remotely as well as alerting the user when it’s time for filter replacements and providing up-to-date information from all the sensors in the HRV.

The project builds on a previous project which adapted an ESP32 to interact with the CAN bus used on these devices. With these upgrades the user can forgo the $300 proprietary upgrade that would be needed to get the same functionality otherwise. It’s also fully open-source so all that’s needed is to flash the firmware, replace the display, and enjoy the fresh air. There’s other modern HVAC equipment that can benefit from new controllers and a bit of automation as well.

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Windows 95, With Just A Floppy Drive

October 26, 2025 by 45 Comments

It’s something of a shock to be reminded that Microsoft’s Windows 95 is now 30 years old — but the PC operating system that brought 32-bit computing to the masses and left behind a graphical interface legacy which persists to this day, is now old enough that many in the community have never actually seen it. The original requirements were a 386 or better, 4 megabytes of memory, and a hard drive. [Robert’s Retro] is exploding one of those requirements, creating a full Windows 95 install using only a floppy drive.

As you might imagine, even if you had one of the super-rare 2.88 megabyte drives, such a feat would require a few tricks. In this case the biggest trick is the FlashPath, a curious 1990s peripheral that allows a SmartMedia card to be used in a floppy drive. With a special DOS driver it allows what is in effect a 32 megabyte floppy disk, but even that’s not enough for ’95. In come a couple of further tricks, installing Windows 95 to a compressed DriveSpace volume which is copied to the FlashPath, and copying the Drivespace volume to a RAM drive and mounting it, on boot. It needs a conventional floppy to boot before swapping to the FlashPath and it seems the copying process is extremely slow, but we’d expect Windows 95 from RAM to be very quick indeed.

There have been other minimalist Windows 95s over the years, but what makes this one unusual is that it’s a full install. Five years ago at the OS’s quarter century we took a look at it with 2020 eyes, and tried gauge its effect on modern desktops.

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A Nuclear Physics Lab In Your Pocket

October 25, 2025 by 17 Comments

If you want to work with radioactive material, a cheap Geiger counter isn’t really what you want. According to [Project 326], you need a gamma ray spectrometer. The video below reviews the Radiacode 110. The channel has reviewed other Radiacode products, and they haven’t always been pleased with them, apparently. Is the 110 better?

The little spectrometer uses a scintillation crystal and performs a spectrogram on the result. It has a large library of materials so, at least for radioactive materials, you can point it at something and tell what kind of material you are dealing with and how radioactive it is.

While the smartphone app seems well done, the Windows application left something to be desired. Even still, it was able to identify several isotopes. The device can even pick up some alpha emitters that don’t directly register. However, it can identify some materials by different decomposition products. Unlike some earlier models, this device is supposed to be highly sensitive and high-resolution.

To confirm this, [Project 326] built a lead shielding structure and read a reference sample. Crunching some numbers confirmed that the claimed performance was accurate. It could even read very low-energy sources, though there were some limitations. The ergonomics of the device could be better, apparently, but it does deliver on performance.

Do you need a gamma ray spectrometer? We don’t know, but we suspect if you do, you don’t need us to tell you.

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A photo of the robot and the controller

A Simple $25 Robot Based On The ESP32

October 25, 2025 by 16 Comments

[Paul McCabe] wrote in to let us know about his $25 robot. This small wheeled robot is based on an ESP32 and made using cardboard and hot glue.

You drive the contraption using a Bluetooth game controller thanks to the Bluepad32 library, which boasts a long list of supported hardware. [Paul] provides a Bill of Materials (BoM), complete with current component pricing. We don’t know about you, but it struck us as funny that the microcontroller is less expensive than the battery! Ah, the times we live in. Also [Paul] assumes you already have an appropriate Bluetooth controller and doesn’t include that in the total cost.

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What If Tinkercad Was Self-Hosted?

October 25, 2025 by 31 Comments

While we use a lot of CAD tools, many of us are fans of Tinkercad — especially for working with kids or just doing something quick. But many people dislike having to work across the Internet with their work stored on someone’s servers. We get it. So does [CommonWealthRobotics], which offers CaDoodle. It is nearly a total clone of Tinkercad but runs on Windows, Linux, Mac, or even Chrome OS.

Is it exactly Tinkercad? No, but that’s not always a bad thing. For example, CaDoodle can work with Blender, FreeCAD, OpenSCAD, and more. However, on the business end, it sure looks like the core functions of Tinkercad.

The program appears fairly new, so you have to make some allowances. For example, the Linux AppImage seems to have difficulty loading plugins (which it needs to import many of its file formats). In addition, on at least some systems, you have to resize the window after it starts, or it won’t respond. But, overall, it is pretty impressive. The Settings, by the way, has a checkbox for advanced features, and there are some other goodies there, too.

One reason we found this interesting is that we sometimes go into schools, and they don’t want us to have kids on the Internet. Of course, they don’t like us installing random software either, so you can pick your battles.

Tinkercad, of course, continues to add features. Not all of which you’d expect in a drawing package.

A clay mug is placed on a fire brick. Portions of the mug are glowing orange hot, and the heat is spreading across the surface. Some portions of the mug have cooled, and the heat has not reached other parts.

Thermite Pottery Fires Itself

October 25, 2025 by 28 Comments

Finely powdered aluminium can make almost anything more pyrotechnically interesting, from fireworks to machine shop cleanups – even ceramics, as [Degree of Freedom] discovered. He was experimenting with mixing aluminium powder with various other substances to see whether they could make a thermite-like combination, and found that he could shape a paste of aluminium powder and clay into a form, dry it, and ignite it. After burning, it left behind a hard ceramic material.

[Degree of Freedom] was naturally interested in the possibilities of self-firing clay, so he ran a series of experiments to optimize the composition, and found that a mixture of three parts of aluminium to five parts clay by volume worked best. However, he noticed that bubbles of hydrogen were forming under the surface of the clay, which could cause cracks during the firing. The aluminium was reacting with water to form the bubbles, somewhat like a unwanted form of aerated concrete, and for some reason the kaolinite in clay seemed to accelerate the reaction. Trying to passivate the aluminium by heating it in air or water didn’t prevent the reaction, but [Degree of Freedom] did find that clay extracted from the dirt in his back yard didn’t accelerate it as kaolinite did, and the mixture could dry out without forming bubbles.

This mixture wasn’t totally reliable, so to make it a bit more consistent [Degree of Freedom] added some iron oxide to accelerate the burn through an actual thermite reaction – some mixtures burned hot enough to start to melt the clay. After many tests, he found that sixteen parts clay, seven parts aluminium, and five parts iron oxide gave the best results. He fired two cups made of the mixture, a thin rod, and a cube, with mixed results. The clay expanded a bit during firing, which sometimes produced a rough finish, cracking, and fragility, but in some cases it was surprisingly strong.

The actual chemistry at work in the clay-aluminium mixtures is a bit obscure, but not all thermite reactions need to involve iron oxide, so there might have been some thermite component even in the earlier mixtures. If you need heat rather than ceramic, we’ve also seen a moldable thermite paste extruded from a 3D printer.

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Relay Computer Knows The Sequence

October 25, 2025 by 11 Comments

When we first saw [DiPDoT’s] homebrew computer, we thought it was an Altair 8800. But, no. While it has a very familiar front panel, the working parts are all based on relays. While it isn’t finished, the machine can already do some simple calculations as you can see in the video below.

Turns out, the Altair front panel isn’t a coincidence. He wants to put the device in an Altair-style case. This limits him to two backplane cards, but he’s running out of space, so part of what he does in the video is redesign the backplanes.

We need to watch some more of these videos to figure out how he’s making his logic gates. A common approach is to wire AND gates as series relays and OR gates as parallel relays. However, there are some advantages to using relays as two-to-one multiplexers, which can create any logic gate you want.

If you just want to see the computer run, you can watch it generate a Fibonacci sequence around the 14:30 mark. Glorious sound from a beautiful bunch of relays. Not exactly a speed demon, mind you, but not half bad for a bunch of electromechanical relays.

There was a time when computers like this were state-of-the-art. In a way, we miss those days. But then again, in some ways, we don’t.

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