Schematic of quantum measurement basis on whiteboard

Shedding Light On Quantum Measurement With Calcite

January 26, 2025 by Heidi Ulrich 18 Comments

Have you ever struggled with the concept of quantum measurement, feeling it’s unnecessarily abstract? You’re not alone. Enter this guide by [Mithuna] from Looking Glass Universe, where she circles back on the concept of measurement basis in quantum mechanics using a rather simple piece of calcite crystal. We wrote about similar endeavours in reflection on Shanni Prutchi’s talk at the Hackaday SuperConference in 2015. If that memory got a bit dusty in your mind, here’s a quick course to make things click again.

In essence, calcite splits a beam of light into two dots based on polarization. By aligning filters and rotating angles, you can observe how light behaves when forced into ‘choices’. The dots you see are a direct representation of the light’s polarization states. Now this isn’t just a neat trick for photons; it’s a practical window into the probability-driven nature of quantum systems.

Even with just one photon passing through per second, the calcite setup demonstrates how light ‘chooses’ a path, revealing the probabilistic essence of quantum mechanics. Using common materials (laser pointers, polarizing filters, and calcite), anyone can reproduce this experiment at home.

If this sparks curiosity, explore Hackaday’s archives for quantum mechanics. Or just find yourself a good slice of calcite online, steal the laser pointer from your cat’s toy bin, and get going!

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Logging Baby’s Day In Linux

January 7, 2025 by Tom Nardi 37 Comments

There’s plenty of surprises to be had when you become a parent, and one of the first is that it’s suddenly your job to record the frequency of your infant’s various bodily functions in exacting detail. How many times did the little tyke eat, how long did they sleep, and perhaps most critically, how many times did they poop. The pediatrician will expect you to know these things, so you better start keeping notes.

Or, if you’re [Triceratops Labs], you build a physical button panel that will keep tabs on the info for you. At the press of each button, a log entry is made on the connected Raspberry Pi Zero W, which eventually makes its way to a web interface that you can view to see all of Junior’s statistics.

In terms of hardware, this one is quite simple — it’s really just an array of arcade-style push buttons wired directly into the Pi’s GPIO header. Where it shines is in the software. This project could have been just a Python script and a text file, but instead it uses a MariaDB database on the back-end, with Apache and PHP serving up the web page, and a custom Systemd service to tie it all together. In other words, it’s what happens when you let a Linux admin play with a soldering iron.

It probably won’t come as much surprise to find that hackers often come up with elaborate monitoring systems for their newborn children, after all, it’s a great excuse for a new project. This machine learning crib camera comes to mind.

PoE-Power Protection: The Hornet Nest Alarm Panel

January 4, 2025 by Heidi Ulrich 30 Comments

Have you ever thought of giving new buzz to outdated wired alarm systems or saving money while upgrading your home security? The Hornet Nest Alarm Panel, to which hacker [Patrick van Oosterwijck] contributes, does just that. Designed for domotics enthusiasts, it offers 42 sensor zones and seamless integration with Home Assistant and ESPHome. This open-source gem uses the wESP32 board, which combines an ESP32 with Ethernet and Power over Ethernet (PoE) for robust, reliable connectivity. Check out the Crowd Supply campaign for details.

So what makes this Hornet Nest special? Besides its hackable nature, it repurposes existing wired sensors, reducing waste and cost. Unlike WiFi-dependent solutions, the PoE-powered ESP32 ensures stable performance, even in hard-to-reach locations. The optional USB programming port is genius—it’s there when you need it but doesn’t clutter the board when you don’t. With its isolated circuits, long-cable safety, and smart Ethernet, WiFi, and Bluetooth combination, this system ticks every DIY box.

Hackaday has featured other DIY PoE-powered projects, offering more inspiration for smart automation enthusiasts.

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Let It Snow With A Sub $100 Snowmaking Machine.

December 28, 2024 by Adam Fabio 29 Comments

[Mattmopar] figured out how to get a white Christmas even if the weather isn’t frightful. He built a simple DIY snow making machine with a few plumbing parts, and tools you probably already have. Snowmaking machines used on the ski slopes cost tens of thousands of dollars. Even the “low-cost” home versions are $400 and up.

[Matt] cut things down to the basics. Snowmaking requires two ingredients: Water and compressed air. The water is coming from a cheap electric pressure washer he found used. The air pressure is from an old air compressor. [Matt] is using his shop compressor – but even a cheap compressor will do fine.

The cold is an unforgiving environment though – so a few changes are needed. The trick is to use garden hose instead of air hose. Traditional air hose has a rather small hole. This leads to ice clogs coming from the compressor itself. A check valve also ensures that water from the pressure washer doesn’t back up into the compressor.

The nozzles are pressure washer nozzles. Two 40 degree nozzles for the water, and a 65 degree nozzle for the air/water mix. In true hacker style, the frame of the machine is a ladder, and the gun attached via zip-ties.

Of course you still need cold temperatures for this to work, but that’s not too hard in the winter months. Now if you have the opposite problem of too much snow, check out this self clearing concrete.

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A woman in a dark green shirt and grey jeans holds a set of cinnamon pants. She is standing next to a burnt orange cushioned and backed-chair. The arm rests, legs, and outer circular rack are a blonde wood. It looks somewhat mid-century modern. A number of differently-colored clothes line the wall in the background.

Uncanny Valley Of Clean Conquered By Clever Chair

December 27, 2024 by Navarre Bartz 11 Comments

Do you ever have clothes that you only wore for a few hours, so you don’t want to wash them, but it still seems icky to put them back in the drawer or closet? What if you had a dedicated place to put them instead of on your floor or piled on a chair in the corner? [Simone Giertz] has a tidier solution for you.

On top of the quasi-dirty clothing conundrum, [Giertz]’s small space means she wanted to come up with a functional, yet attractive way to wrangle these clothes. By combining the time-honored tradition of hanging clothes on the back of a chair and the space-saving efficiency of a Lazy Susan, she was able to create a chair with a rotating rack to tuck the clothes out of the way when not wearing them.

The circular rack attached to the chair orbits around a circular seat and arm rests allowing clothes to be deposited on the chair from the front and conveniently pushed to the back so they remain out of sight and out of mind until you need them. The hardware chosen seems to be pretty strong as well given the number of items placed on the rail during the demonstration portion of the video. We also really like how [Giertz] challenged herself to “CAD celibacy” for the duration of the build to try to build it quick.

If you want to see some other clever furniture hacks, how about repurposing the seats from an old subway, or hacking IKEA furniture to be more accessible?

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Holiday Jukebox Gets ESP32, Home Assistant Support

December 24, 2024 by Tom Nardi 14 Comments

If we’ve learned anything over the years, it’s that the only thing hardware hackers love more than a device festooned with buttons is one that’s covered in LEDs — so it’s no surprise that this “Mr Christmas” jukebox caught the eye of [Roberts Retro]. But while the holiday gadget might have been mildly entertaining in its stock configuration, he quickly realized that what it really needed was an ESP32 retrofit. After all, what good are all those buttons and LEDs if you can’t bend them to your will?

For the first half of the video, [Robert] treats us to a detailed teardown of the device, which as you might imagine, is largely hollow inside. This gave him plenty of room to graft in new hardware, which is really the best gift any of us could hope to find under the tree. In addition to the ESP32 development board, the jukebox also received a number of WS2812B addressable RGB LEDs, and a DFPlayer module to handle music playback.

With all the buttons wired up to inputs on the ESP32, [Robert] can reconfigure the jukebox to do pretty much whatever he wants with just changes to the software. In the video, he demonstrates how the buttons can be used to trigger the playback of individual songs stored on the DFPlayer’s SD card, which essentially replicates it’s stock functionality. A few lines of changed code later, those same buttons can be used to control devices via Home Assistant.

To get into the holiday spirit, [Roberts Retro] shows off the completed jukebox controlling his ESP-enabled LEGO train set — another of his festive upgrades that we covered back in 2022.

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Custom Firmware For Even Cheaper Bluetooth Thermometers

December 21, 2024 by Tom Nardi 33 Comments

Readers may recall when we first covered the $5 Xiaomi LYWSD03MMC temperature and humidity sensor back in 2020. Prolific hacker [Aaron Christophel] wrote a custom firmware for the affordable gadget that was so capable and well implemented that it kicked off a whole new community.

It’s recently been brought to our attention that the Xiaomi thermometer has become so popular that clones have started popping up. Often sold under the Tuya brand, these versions look very similar to Xiaomi’s offering but can be had for as little as $1 each from the usual Chinese importers. Even better, they’ve got their very own open-source custom firmware.

The firmware comes from [pvvx], who also helms the most active fork of [Aaron]’s original firmware for the Xiaomi thermometer. Doing a bit of spot-checking between the repositories, it’s not immediately clear that any meaningful code is shared between the two projects. However, once installed, they offer similar capabilities to the user, such as integration with Home Assistant. Perhaps the most significant difference between the two projects is that, at least for the initial flash, you need to hook the Tuya units up to your computer with a USB serial adapter. Considering that one of the highlights of the Xiaomi custom firmware was its exceptionally easy wireless installation, this is a considerable step backward.

Below is a video from a few months back that [Maker’s Fun Duck] put together, where he takes apart one of these clones and shows the installation process for the custom firmware. Our overall impression is that it’s probably worth the few extra dollars to get the original Xiaomi hardware, although the display on the clone seems much brighter. In any event, we’re always happy to see the community coming up with free and open-source firmware for an otherwise locked-down gadget.

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