Mysterious Files PH

Macropads can be as simple as a few buttons hooked up to a microcontroller to do the USB HID dance and talk to a PC. However, you can go a lot further, too. [CNCDan] demonstrates this well with his sleek macropad build, which throws haptic feedback into the mix.

The build features six programmable macro buttons, which are situated either on side of a 128×64 OLED display. This setup allows the OLED screen to show icons that explain the functionality of each button. There’s also a nice large rotary knob, surrounded by 20 addressable WS2811 LEDs for visual feedback. Underneath the knob lives an an encoder, as well as a brushless motor typically used in gimbal builds, which is driven by a TMC6300 motor driver board. Everything is laced up to a Waveshare RP2040 Plus devboard which runs the show. It’s responsible for controlling the motors, reading the knob and switches, and speaking USB to the PC that it’s plugged into.

It’s a compact device that nonetheless should prove to be a good productivity booster on the bench. We’ve featured [CNCDan’s] work before, too, such as this nifty DIY VR headset.

The heat pump has become a common fixture in many parts of modern life. We now have reverse-cycle air conditioning, heat pump hot water systems, and even heat pump dryers. These home appliances have all been marketed as upgrades over simpler technologies from the past, and offer improved efficiency and performance for a somewhat-higher purchase price.

Heat pumps aren’t just for the home, though. They’re becoming an increasingly important part of major public works projects, as utility providers try to do ever more with ever less energy in an attempt to save the planet. These days, heat pumps are getting bigger, and will be doing ever grander things in years to come.

Magical Efficiency

The heat pump is a particularly attractive tool because it has a near-mystical property that virtually no other machine does. It is capable of delivering more heat energy than the amount of electricity fed into it, appearing to effectively have an efficiency greater than unity. We’re told that thermodynamic laws mean that we can never get more energy out than we put in. If you put 1 kW of electrical energy into a resistive heating element, which is near 100% efficient, you should get almost 1 kW of heat out of it, but never a hair more than that. But with a heat pump, you could get 1.5 kW, or even 2 kW for your humble 1 kW input. The trick is that the heat pump is not actually a magical device that can multiply energy out of nothing. Instead, the heat pump’s trick is that it’s not turning your 1 kW input into heat energy. It’s using 1 kW of energy to move heat from one place to another. If you’re running a heat pump-based HVAC system to cool your home, for example, it might use 2 kW of electricity to pump 3 to 4 kW of heat from your lounge room and dissipate it outdoors. Since the outdoors doesn’t change much in temperature when you pump out the heat from your home, you can keep doing this pretty much all day. You can even reverse the flow if your heat pump system allows it, instead pumping heat from the outdoors into your home. This works well until temperatures get so low that there isn’t enough heat left in the outdoors to appreciably warm your house up.

The heat pump achieves the feat of making heat go where we want it to go via the use of refrigerant. Specifically, refrigerant enters the compressor as a low pressure and low temperature vapor. It exits as a gas at high temperature and high pressure, and is then passed through a series of condenser coils. As it passes through, it releases heat to the surrounding environment and reduces in temperature, condensing into a liquid. From there, the liquid, still under high pressure, passes through an expansion valve, which rapidly lowers the pressure and drops the temperature further. The liquid is now cold, and passes through an evaporator coil where it picks up heat from the surroundings and turns back into a low-pressure, low-temperature vapor to start the cycle again as it heads back to the compressor. This system runs your fridge, your car’s air conditioner, and is used in so many other applications where it’s desirable to make something colder or hotter as efficiently as possible. You just choose which direction you want to pump the heat and design the system accordingly. Air conditioners and fridges pump heat out of a confined space, heaters and dryers pump it in, and so on. It’s heat pumps all the way down!

Bigger Applications

Thus far, you’ve probably used many a heat pump in your daily life, whether it be for heating, cooling, or drying clothes. However, there is a new push to build ever-larger heat pumps to work on the municipal scale, rather than simply serving individual households. The hope is to make utilities more energy efficient, and thus cheaper and greener in turn, by taking advantage of the efficiency gains offered by the magic of the heat pump.

One such project is taking place just off the River Rhine in Germany. A pair of massive heat pump units are being constructed by MVV Energie, each with a capacity of 82.5 megawatts. They will deliver heat to a total of 40,000 homes via a district heating system, and will be constructed on the site of a former coal power plant. Each pump will effectively draw energy out of the massive watery heat battery that is the River Rhine, and use it to warm homes in the local area. Thankfully, the river’s capacity is large enough that drawing all that heat out of the river should only affect temperatures of the water by around 0.1 C.

The Rhine project builds upon a previous effort to install a large heat-pump heating system in Mannheim, in partnership with Siemens Energy. That installation draws 7 megawatts of electricity to supply 20 megawatts of heating to the local district heating grid. Installed in 2023, it supplies the heating needs of 3,500 local households.

A similar project is underway in Denmark, which will supply 177 megawatts of heat to homes in Aalborg. The installation of four 44 megawatt MAN Technology heat pumps will be hooked up to the existing district heating system, which is also supported by other sources including waste heat from a local cement factory. The benefit of using smaller individual units is that it allows some of the pumps to be shut down when heating demand is lower, as winter passes through autumn into summer.

What makes these projects special is their sheer scale. Rather than being measured in the kilowatt scale like home appliances, they’re measured in the many tens of megawatts, delivering heating to entire neighborhoods instead of single homes. As it turns out, heat pumps work just fine at large scales—you just need to build them out of bigger components. Bigger compressors, bigger expansion valves, and bigger condensors and evaporators—all of these combine to let you pump enormous amounts of heat from one place to another. As utilities around the world seek ever greater efficiency in new projects, heat pumps will likely grow larger and be deployed ever more widely, seeking to take advantage of the free heat on offer in the earth, water, and air around us. After all, there’s no point dumping energy into making heat when you can just move some that’s already there!

Over the past couple of years with the Jenny’s Daily Drivers series, we’ve looked at a number of unusual or noteworthy operating systems. Among them has been ReactOS, an open source clone of a millennium-era Windows OS, which we tried back in November. It’s one of those slow-burn projects we know has been around for a long time, but still it’s a surprise to find we’ve reached the 30th anniversary of the first ReactOS code commit.

The post is a run through the project’s history, and having followed it for a long time we recognize some of the milestones from the various ISOs we downloaded and tried back in the day. At the end it looks into the future with plans to support more up-to-date hardware as well as UEFI, which we hope will keep it relevant.

When we tried it, we found an OS which could indeed be a Daily Driver on which a Hackaday article could be written — even if it wasn’t the slickest experience on the block. It doesn’t matter that it’s taken a while, if you’re used to Windows XP this has become a usable replacement. We came to the conclusion that like FreeDOS it could find a niche in places where people need a modern version of the old OS to run older software, but perhaps as it now moves towards its mature phase it will move beyond that. We salute the ReactOS developers for bringing it this far, and for not giving up.

You can read our Daily Drivers review of a recent ReactOS build here.

Kei trucks are very versatile vehicles, but their stock powerplant can leave a bit to be desired. If you need more power, why not try an electric conversion?

[Ron “Mr. G” Grosinger] is a high school auto shop and welding teacher who worked with his students to replace the 40 hp gas motor in this Daihatsu Hijet with the 127 hp of a Hyper 9 electric motor. The motor sits in the original engine bay under the cab and is mated to the stock transmission with a custom adapter plate made from plate steel for less than $150. We really appreciate how they left all the electronics exposed to see what makes the conversion tick.

The faux battery was made by a foam sculptor friend out of urethane foam shaped with a carving knife and then painted. It slides on a set of unistrut trolleys and reveals the 5 salvaged Tesla battery modules that power the vehicle. The fold down sides of the truck bed allow easy access to anything not already exposed if any tweaking is necessary.

We’ve seen a kei truck become a camper as well or an ebike powered with actual power tool batteries. If you’re thinking of your own electric conversion, which battery is best?

This week Jonathan chats with Olaf Andreas Schulte and Lars Kiesow about Opencast, the video management system for education. What does Opencast let a school or university accomplish, how has that changed over the last decade, and what exciting new things are coming? Watch to find out!

• https://explore.opencast.org/
• https://opencast.org/
• https://opencast.org/2025/12/19/opencast-apereo-update/

Did you know you can watch the live recording of the show right on our YouTube Channel? Have someone you’d like us to interview? Let us know, or have the guest contact us! Take a look at the schedule here.

Direct Download in DRM-free MP3.

If you’d rather read along, here’s the transcript for this week’s episode.

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Theme music: “Newer Wave” Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

I just love it when y’all send in your projects, so thanks, [Kai]! But were do I even begin with this one? Okay, so, first of all, you need to know that [Kai Ruhl] built an amazing split keyboard with plenty of keys for even someone like me. Be sure to check it out, because the build log is great reading.

But that wasn’t enough — a mousing solution was in order that didn’t require taking [Kai]’s hands off of the keyboard. And so, over the course of several months, the RollerMouse Keyboard came into being. That’s the creation you see here.

Essentially, this is an ortholinear split with a built-in roller bar mouse, which basically acts like a cylindrical trackball. There’s an outer pipe that slides left/right and rolls up and down, and this sits on a stationary inner rod. The actual mouse bit is from a Logitech M-BJ69 optical number.

[Kai] found it unpleasant to work the roller bar using thumbs, so mousing is done via the palm rests. You may find it somewhat unpolished with all that exposed wiring in the middle. But I don’t. I just worry about dust is all. And like, wires getting ripped out accidentally.

All Work and No Play Makes Jack a Dull Boy

As I write this, a terrible snowpocalypse is snuggling up to the southern and mid-western states. What a time to watch The Shining and check out the dullboy prototype by [Blind_Heim].

This is [Blind_Heim]’s first project, and I think it looks mighty fine, especially with those slanty thumb keys. They are [Blind_Heim]’s own creation and were inspired by the design of the 1959 Adler Universal featured in The Shining. (Hence the name of the keyboard.) In case it isn’t obvious, they are meant for Kailh choc v1 switches.

Rev 1 shown here has a nice!nano and supports v1 chocs only. Rev 2 will support v1 and v2, and will have a 40 mm Cirque trackpad in that middle space there. Rev 2 will also be open-source and entirely free of copyright, so watch out for that.

Regarding those thumb keys, [Blind_Heim] says that they wanted something ergonomic and monoblock at first, and so the angles were just for looks. But after using it, he realized they were actually quite useful when it comes to determining which key is which without having to look.

The Centerfold: Downtown Busy Town Is the Place to Be

This desk mat ought to bring back some memories. Hopefully good ones, of daycare and snacks and nap time. Here it is for sale if you feel the need to drive little cars around on it.

As for the keyboard, that’s a Norbauer Heavy Grail Ghost of Christmas Future edition, which was of course a limited release that’s long sold out. I’m sure there are other transparent bodies out there, but good luck finding a bug-eyed, duck-faced keycap.

Do you rock a sweet set of peripherals on a screamin’ desk pad? Send me a picture along with your handle and all the gory details, and you could be featured here!

Historical Clackers: the Saturn

The Virtual Typewriter Museum calls the 1899 Saturn “one of the most impractical machines ever, built with proverbial precision in Switzerland”.

The operation of this blind writer is pretty interesting, and that’s putting it politely. There are nine U-shaped type bars: four on each side beneath the carriage, and one in the middle that swings up from behind.

Each of these type bars holds eight characters, and these are selected by moving a wire up and down the index card using that giant round selector button the left side. The you would strike one of the nine keys corresponding to the column your character appears in.

Evidently the lower case characters were laid out differently than the upper case, which made it even more difficult to use. But hey, Swiss precision.

There is not a lot of information out there about the Saturn, but the Virtual Typewriter Museum does have more shots of various angles.

Finally, a Keyboard Made of Marble and Ceramic

Apparently there was a Kickstarter near the end of 2025 for this thing. Well, this is the first I’ve heard of it. This here is the Keychron Q16 HE 8K ceramic and marble keyboard, which debuted at CES.

This is a luxury keyboard for sure, right down to the pre-lubed Keychron ultra-fast Lime magnetic switches which features Tunnel Magnetoresistance (TMR) and per-key adjustable actuation.

They say it’s built for gaming, but I don’t know. I think it’s built for whatever you want to use it for. It will be available in April. I sincerely hope that it’s like typing on little coffee cups, and it probably sounds amazingly thocky.

Now Tweak Town doesn’t have a whole lot to say about this keyboard, so I found a review to go with it. [YouallareToxic] has quite a bit to say about the keyboard. I think the biggest takeaway from this review is that this keyboard sounds like no other. [YouallareToxic] likens it to a frog guiro. A what? Check out the video below.

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Got a hot tip that has like, anything to do with keyboards? Help me out by sending in a link or two. Don’t want all the Hackaday scribes to see it? Feel free to email me directly.

There are many solutions for remote control keyboards, be they Bluetooth, infrared, or whatever else. Often they leave much to be desired, and come with distinctly underwhelming physical buttons. [konkop] has a solution to these woes we’ve not seen before, turning an ESP32-S3 into a USB HID keyboard with a web interface for typing and some physical keyboard macro buttons. Instead of typing on the thing, you connect to it via WiFi using your phone, tablet, or computer, and type into a web browser. Your typing is then relayed to the USB HID interface.

The full hardware and software for the design is in the GitHub repository. The macro buttons use Cherry MX keys, and are mapped by default to the common control sequences that most of us would find useful. The software uses Visual Studio Code, and PlatformIO.

We like this project, because it solves something we’ve all encountered at one time or another, and it does so in a novel way. Yes, typing on a smartphone screen can be just as annoying as doing so with a fiddly rubber keyboard, but at least many of us already have our smartphones to hand. Previous plug-in keyboard dongles haven’t reached this ease of use.