A Working Intercom From Antique Telephones

Although it can be hard to imagine in today’s semiconductor-powered, digital world, there was electrical technology around before the widespread adoption of the transistor in the latter half of the 1900s that could do more than provide lighting. People figured out clever ways to send information around analog systems, whether that was a telegraph or a telephone. These systems are almost completely obsolete these days thanks to digital technology, leaving a large number of rotary phones and other communications systems relegated to the dustbin of history. [Attoparsec] brought a few of these old machines back to life anyway, setting up a local intercom system with technology faithful to this pre-digital era.

These phones date well before the rotary phone that some of us may be familiar with, to a time where landline phones had batteries installed in them to provide current to the analog voice circuit. A transformer isolated the DC out of the line and amplified the voice signal. A generator was included in parallel which, when operated by hand, could ring the other phones on the line. The challenge to this build was keeping everything period-appropriate, with a few compromises made for the batteries which are D-cell batteries with a recreation case. [Attoparsec] even found cloth wiring meant for guitars to keep the insides looking like they’re still 100 years old. Beyond that, a few plastic parts needed to be fabricated to make sure the circuit was working properly, but for a relatively simple machine the repairs were relatively straightforward.

The other key to getting an intercom set up in a house is exterior to the phones themselves. There needs to be some sort of wiring connecting the phones, and [Attoparsec] had a number of existing phone wiring options already available in his house. He only needed to run a few extra wires to get the phones located in his preferred spots. After everything is hooked up, the phones work just as they would have when they were new, although their actual utility is limited by the availability of things like smartphones. But, if you have enough of these antiques, you can always build your own analog phone network from the ground up to support them all.

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hackaday.com/2026/02/09/a-work…

Upcycling an iPad into a Touchscreen Display for your PC

Installing an RPi Pico board like it’s a modchip. (Credit: Tucker Osman, YouTube)
Although generally iPads tend to keep their resale value, there are a few exceptions, such as when you find yourself burdened with iCloud-locked devices. Instead of tossing these out as e-waste, you can still give them a new, arguably better purpose in life: an external display, with touchscreen functionality if you’re persistent enough. Basically someone like [Tucker Osman], who spent the past months on making the touchscreen functionality play nice in Windows and Linux.

While newer iPads are easy enough to upcycle as an external display as they use eDP (embedded Display Port), the touch controller relies on a number of chips that normally are initialized and controlled by the CPU. Most of the time was thus spent on reverse-engineering this whole process, though rather than a full-depth reverse-engineering, instead the initialization data stream was recorded and played back.

This thus requires that the iPad can still boot into iOS, but as demonstrated in the video it’s good enough to turn iCloud-locked e-waste into a multi-touch display. The SPI data stream that would normally go to the iPad’s SoC is instead intercepted by a Raspberry Pi Pico board which pretends to be a USB HID peripheral to the PC.

If you feel like giving it a short yourself, there’s the GitHub repository with details.

Thanks to [come2] for the tip.

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hackaday.com/2026/02/09/upcycl…

Converting AC Irrigation Valves To DC Operation

Due to historical engineering decisions made many decades ago, a great many irrigation systems rely on solenoid valves that operate on 24 volts AC. This can be inconvenient if you’re trying to integrate those valves with a modern smart home control system. [Johan] had read that there were ways to convert these valves to more convenient DC operation, and dived into the task himself.

As [Johan] found, simply wiring these valves up to DC voltage doesn’t go well. You tend to have to lower the voltage to avoid overheating, since the inductance effect used to limit the AC current doesn’t work at DC. However, even at as low as 12 volts, you might still overheat the solenoids, or you might not have enough current to activate the solenoid properly.

The workaround involves wiring up a current limiting resistor with a large capacitor in parallel. When firing 12 volts down the line to a solenoid valve, the resistor acts as a current limiter, while the parallel cap is initially a short circuit. This allows a high current initially, that slowly tails off to the limited value as the capacitor reaches full charge. This ensures the solenoid valve switches hard as required, but keeps the current level lower over the long term to avoid overheating. According to [Johan], this allows running 24V AC solenoid valves with a 12V DC supply and some simple off-the-shelf relay boards.

We’ve seen similar work before, which was applied to great effect. Sometimes doing a little hack work on your own can net you great hardware to work with. If you’ve found your own way to irrigate your garden as cheaply and effectively as possible, don’t hesitate to notify the tipsline!

hackaday.com/2026/02/09/conver…

Keebin’ with Kristina: the One with the Height-Adjustable Key Caps

Now, we can’t call these LEGO key caps for obvious reasons, but also because they don’t actually work with standard LEGO. But that’s just fine and dandy, because they’re height-adjustable key caps that use the building block principle.

Image by [paper5963] via redditNow you could just as easily build wells as the dome shape pictured here, and I’d really like to see that one of these days.

In the caption of the gallery, [paper5963] mentions foam. As far as I’ve studied the pictures, it seems to be all 3D-printed material. If they were foam, they would likely be porous and would attract and hold all kinds of nastiness. Right?

[paper5963] says that there are various parts that add on to these, not just flat tops. There are slopes and curves, too. They are also designing these for narrow pitch, and say they are planning to release the files. Exciting!

Fold-able Keyboard Goes Anywhere

[pinya] says this is a remake of their Crabapplepad V2 into something that folds. They take it along in their backpack and use it either with a phone or a Lenovo Legion Go linux tablet. The original PCB was designed for this possibility, and now it’s a thing.

Image by [pinya] via redditThis is the same board as the CrabappleV2, but cut into three pieces and rejoined with flexy silicone wire. That stuff is already great; here’s another use case for it.

The hinges are the friction type you’d find on a laptop, so they’re strong and can stay in any position. The way they’re mounted doesn’t allow for much tenting, but it does allow for a few degrees. Otherwise, the whole thing would become unstable.

This baby has soldered brown Kailh chocs (yay!) with the diodes buried snugly beneath them. The switches were still exposed and snagging on things in the backpack, so [pinya] whipped up a nice little felt case for it.

Since there’s still enough space at the top of the board, [pinya] might add a built-in phone stand. I’m interested to see how that goes with the weight of the phone and all.

The Centerfold: These 3D-Printed Key Caps

Image by [strings_and_tines] via redditAnd now for some completely different 3D-printed key caps, this time from [strings_and_tines]. These are beautiful, and I love the font of the legends and the texture of the tops. Really wish I could touch them. Evidently [strings_and_tines] was not finding key caps with large enough legends for their silakka54 and so they whipped these up using a Bambu Lab A1 with AMS to handle the two colors.

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 Lovely Waverley

This elegant late-Victorian piece is not only beautiful to look at, it has a special place in history. The Waverley was one of only four typewriters ever produced with a rear-downstrike arrangement of type bars. Basically, the bars strike the paper from the top and rear of the machine.

In case you’re wondering, the other three with this distinction are the Brooks, the Fitch, and the North’s, which this resembles quite a lot.
Image via The Antikey Chop
So, how does a rear-downstriker operate? The main issue is feeding the paper. The inventors Edward Smith Higgins and Henry Charles Jenkins created a system that fed the sheet from the front of the platen, wound around it, and then was expelled into that lovely basket on the front, where they would become neatly coiled and out of the visual path to the platen.

The Waverley has other notable features such as a shifting system that completely disengages the lower case type bars and engages the separate, upper case type bars. So each type bar only has one character.

It also has proportional spacing, but only for the widest letters (M and W). The carriage moves a little bit further to account for their extra width.

There’s a separate Space key in the upper right that moves the carriage only the width of one character, whereas the Space bar moves it twice as far to separate the words. This last is one of those features you’d have to train yourself to do, I would think: you can simultaneously push the Space bar while typing the last letter of a word, and then you’re immediately ready to type the next word.

Unfortunately, the Waverley Type-Writer Co. disbanded after just one year of production because of a lack of working capital. It may have just been too complex and thus difficult to produce.

Finally, a Truly Modular Keyboard Complete Input System

Would you like a modular keyboard? Or would you prefer an entire input system? Dutch company Naya are back with the Connect, which looks less like a ‘sensory nightmare’ than the Create, their ergonomic modular keyboard.

Image by [Naya] via New AtlasI suppose it depends on your work and play. I for one would not make use of most of the mouse-like bits, but I would appreciate a tack-on 10-key thing and a set of macro keys for the other side.

And I’m sure left-handers will appreciate that the 10-key thing can go on either the left or right. But you don’t have to use it as a 10-key. It’s essentially just a second macro module with 24 keys. (Not pictured.)

I love New Atlas’ opening salvo: “This might just be the most engineered desktop gear I’ve ever come across.” Much like the ergonomic Create, the four round things are as follows: a customizable trackpad, a 40 mm trackball, a rotary encoder, and a 6-DoF spatial mouse. I will spare you their ethereal names.
See? Sort of? Dishing. Image via Kickstarter
The keyboard itself is a 75%, 85-key number in a unibody of machined aluminium. It has hot-swappable Kailh Choc V2s, and those keycaps are allegedly dished, but they look flat as Kansas to me. Oh, okay; if you look at the many pictures on Kickstarter, you can see the dishing.

Here’s the kicker: it doesn’t come with everything. You either go with the base keyboard and add modules, or get the Dock (the thing on the right up there with four keys and a hole) and attach modules to that. Also, it’s in the Kickstarter phase as I alluded, but it’s something like 4,000% funded already, so.

The keyboard by itself isn’t that much — $119 for early birds — and the Dock is even cheaper. But they aren’t going to ship for more than a year, so consider that.

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.

hackaday.com/2026/02/09/keebin…

Living in the (LLM) Past

In the early days of AI, a common example program was the hexapawn game. This extremely simplified version of a chess program learned to play with your help. When the computer made a bad move, you’d punish it. However, people quickly realized they could punish good moves to ensure they always won against the computer. Large language models (LLMs) seem to know “everything,” but everything is whatever happens to be on the Internet, seahorse emojis and all. That got [Hayk Grigorian] thinking, so he built TimeCapsule LLM to have AI with only historical data.

Sure, you could tell a modern chatbot to pretend it was in, say, 1875 London and answer accordingly. However, you have to remember that chatbots are statistical in nature, so they could easily slip in modern knowledge. Since TimeCapsule only knows data from 1875 and earlier, it will be happy to tell you that travel to the moon is impossible, for example. If you ask a traditional LLM to roleplay, it will often hint at things you know to be true, but would not have been known by anyone of that particular time period.

Chatting with ChatGPT and telling it that it was a person living in Glasgow in 1200 limited its knowledge somewhat. Yet it was also able to hint about North America and the existence of the atom. Granted, the Norse apparently found North America around the year 1000, and Democritus wrote about indivisible matter in the fifth century. But that knowledge would not have been widespread among common people in the year 1200. Training on period texts would surely give a better representation of a historical person.

The model uses texts from 1800 to 1875 published in London. In total, there is about 90 GB of text files in the training corpus. Is this practical? There is academic interest in recreating period-accurate models to study history. Some also see it as a way to track both biases of the period and contrast them with biases found in data today. Of course, unlike the Internet, surviving documents from the 1800s are less likely to have trivialities in them, so it isn’t clear just how accurate a model like this would be for that sort of purpose.

Instead of reading the news, LLMs can write it. Just remember that the statistical nature of LLMs makes them easy to manipulate during training, too.

Featured Art: Royal Courts of Justice in London about 1870, Public Domain

hackaday.com/2026/02/09/living…

Ask Hackaday: How Do You Detect Hidden Cameras?

The BBC recently published an exposé revealing that some Chinese subscription sites charge for access to their network of hundreds of hidden cameras in hotel rooms. Of course, this is presumably without the consent of the hotel management and probably isn’t specifically a problem in China. After all, cameras can now be very tiny, so it is extremely easy to rent a hotel room or a vacation rental and bug it. This is illegal, China has laws against spy cameras, and hotels are required to check for them, the BBC notes. However, there is a problem: At least one camera found didn’t show up on conventional camera detectors. So we wanted to ask you, Hackaday: How do you detect hidden cameras?

How it Works

Commercial detectors typically use one of two techniques. It is easy to scan for RF signals, and if the camera is emitting WiFi or another frequency you expect cameras to use, that works. But it also misses plenty. A camera might be hardwired, for example. Or store data on an SD card for later. If you have a camera that transmits on a strange frequency, you won’t find it. Or you could hide the camera near something else that transmits. So if your scanner shows a lot of RF around a WiFi router, you won’t be able to figure out that it is actually the router and a small camera.

Fire alarm? Camera? It is both!
The other common method uses a beam of light or a laser to try to see reflections of lenses, which will be retroreflective. The user views the room through a viewfinder, and any light that comes directly back will show up in the view. Despite some false positives, this method will find cameras even if they are not powered or transmitting. Even shining a flashlight, maybe from the same cell phone, around a dark room might uncover some camera devices.

There are a few other techniques. If you assume a spy camera probably uses IR lighting to see you at night, you can scan for that. A good tip is that your cell phone camera can probably see IR. (Test it on an IR remote control.) So looking around with your phone camera is a good, free way to find some cameras. A thermal imager might show hidden equipment, too, although it might be hard to determine if it is actually a camera or not.

You might be thinking: just look for the camera. But that’s not always simple. In the BBC article, the camera was the size of a pencil eraser. Not to mention, a quick search of your favorite retailer will reveal cameras made to look like smoke detectors, stuffed toys, USB chargers, and more. You can even get small cameras that can mount a fake button or screw head on the lens.

Testing

[Project Farm] has a video that tests a few detectors. The problem, of course, is that there are different kinds of cameras. Detecting the test camera doesn’t mean it will detect all cameras. Still, you can get some idea of how effective some detectors are compared to others.

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Your Turn?

Given that none of the current ways to detect cameras work perfectly, what would you build to find them? Maybe an NLJD? Or maybe some tech to blind them? Tell us what you think in the comments.

hackaday.com/2026/02/09/ask-ha…