Misc Hacks

4133 Articles

A Train Departure Board For The Home

July 23, 2026 by 10 Comments

Trains are a great way to get around. You just have to make sure you’re across the schedule if you intend to get where you’re going in a timely manner. Train departure boards exist for that very purpose. As a train fan, [Jon] always wanted such a thing, so decided to build one for himself. 

The build started, as so many do, with a Raspberry Pi 4, with [Jon] deciding on the 1GB model. Hooked up to either an Adafruit RGB Matrix Bonnet, or an Electrodragon 3-port RGB Matrix board, it’s then possible to get the Pi running three to four HUB75E LED matrixes. Each matrix consists of 128 x 64 pixels, so stacking up a bunch of them can make a nicely-sized departure board that’s easily readable. [Jon] was sure to hook up a nice, juicy 5-amp 5-volt power supply to ensure there wouldn’t be any surprise brownouts under normal usage conditions. From there, it’s simply a matter of having the Pi query the Rail Data Marketplace in order to get the relevant schedule data to display on the board.

If you want to get information on your local rail services at a glance, or just want to impress your fellow foamers at your next railfan gathering, a build like this is a great way to go. We’ve seen similar builds before, too. Video after the break.

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Mic Jammer Relies On Ultrasound

July 23, 2026 by 15 Comments

Today’s phone microphones are perfectly adept at picking up sound in all sorts of conditions, and they’re backed by all kinds of processing techniques to filter out noise and capture clean audio. [mcore1976] has been working on a device to jam phone microphones that might be listening in, however, countering fancy processing techniques in turn. 

The build uses a microcontroller brain to control an array of ultrasonic transducers. [mcore1976] has created many revisions of the project, each time improving its ability to jam microphones in modern hardware. The latest revision uses an RP2040 microcontroller and a MOSFET drive stage to control 20-80 ultrasonic transducers. They’re driven with a PWM signal generated from the RP2040 itself. The signal output is specifically modulated to try and confuse the automatic gain control systems used in many modern phones in order to make it difficult for them to record clear audio when the jammer is running. As [mcore1976] demonstrates with an iPhone 17, his voice is completely lost amidst unintelligible garbled noise while the jammer is switched on.

It’s a niche idea, and perhaps most interesting because it affects phone microphones while being largely inaudible to the human ear. We’ve featured other interesting jamming devices of late, too. Video after the break.

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Hackaday Europe 2026: Half Quad, Half Blimp: Test. Fly. Survive.

July 23, 2026 by 9 Comments

A great many drones out there, whether homebuilt or store-bought, follow the same basic format. Four motors, some kind of controller, and a lithium-polymer battery supplying the juice to keep everything in the air. It’s a format that produces a remarkably capable air vehicle, suitable for everything from high-speed camera work to urban search and rescue.

With that said, the format does have its limitations. [Suryansh Sharma] has been working on alternative designs for fancy and interesting drones that are half quadcopter and half blimp, and he came to Hackaday Europe 2026 to tell us all about it.

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A person's hand is shown holding a glass flask in a dark room. An orange-red glow is emanating from the flask in a patches, forming a splash-like pattern near the base of the flask.

A Sloshing-Mercury-Powered Neon Light

July 16, 2026 by 16 Comments

In 1675, while transporting a barometer by night, the astronomer Jean Picard noticed a glow inside its glass tube, just above the mercury. As the mercury sloshed and splashed across the surface of the glass, a static electric charge had built up, which was discharging by ionizing the residual gas molecules inside the evacuated tube. [Styropyro] recreated this effect, and found that the dim glow could be made much stronger by adding some noble gas to the tube.

It starts with a simple recreation: he took a volumetric flask, attached a narrow glass stem to the mouth, added some mercury to the flask, evacuated it with a vacuum pump, and sealed off the glass stem. This produced a faint glow when shaken, but it was only really visible under very low light. When [Styropyro] brought it near a Tesla coil, however, it did glow much more brightly.

Backfilling an identical flask with neon to about 40 millitorr produced a much more spectacular result (a low pressure in the tube is necessary, but moderate pressure variations don’t significantly alter the effect). When shaken even slightly, this neon-containing flask produced a bright orange-red glow just above the surface of the mercury. Points of obstruction, such as those in a zig-zag tube, produced a brighter glow. A krypton-containing tube glowed blue, but less brightly than the neon tube.

Since this is, essentially, a triboelectric effect, other materials besides mercury should work; [Styropyro] tested several materials, and found that pieces of Teflon produced a faint glow, and copper beads a somewhat brighter glow. Unfortunately, Galinstan, the obvious replacement for mercury, wets and coats glass, preventing a charge buildup.

Without an added noble gas, the standard glow of barometric light comes from the excitation of mercury vapors, a glow which can also be seen in mercury rectifiers, and which excites the phosphors of fluorescent light bulbs.

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Hard Drive Speakers Crank Out Classic Demo

June 29, 2026 by 5 Comments

Second Reality is a legendary demoscene release by Future Crew, which won Assembly 1993 with its technical and artistic mastery. [Niv Singer] decided to give the classic demo a spin on a rather unconventional sound system with a particuarly techy twist.

Hard drives are great for storing data. They’re designed for this purpose. What they’re not designed for is acting as speakers, but you can hack them into acting that way if you’re so inclined. For this project, [Niv] pulled apart a whole stack of drives, so they could be repurposed in this way. The principle is simple enough—just feed audio to the coil driving the head, and it will vibrate and wiggle around, creating soundwaves in the air. It’s not particularly effective, and you get limited volume with a terrible frequency response, but that’s half the fun. [Niv] actually took some of this into account, too. Four Western Digital Caviar 500GB drives were chosen for this build, two for the left channel, and two for the right. Each channel had a crossover, allowing one drive to handle low frequencies while the other handled higher ones. For a further nice touch, the platters spin with the beat as well, with [Niv] providing a great explanation on how this was achieved with the use of some nifty PWM tricks.

Files are on Github for the curious. We’ve featured plenty of hard drive speakers before, too. Video after the break.

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A Custom Zigbee Touch Keypad

June 26, 2026 by 8 Comments

[Dominic Buchstaller] wanted a neat, tidy entryway keypad that actually looked good. Prime goals were something slim, wireless, and with no visible screws. Dependency on the cloud was also a no-go. With few ready-to-go options available on the market, he set about whipping up his own.

The heart of the build is an ESP32-C6 microcontroller devboard. This device has the benefit of including Zigbee communication functionality baked right into the chip. It’s hooked up to an MPR121 capacitive touch controller, which allows different segments of the touchpad PCB to act as capacitive buttons for numerical entry. The number labels are directly printed on the PCB solder mask, so there’s no overlay or other label required on top. Power is courtesy of a 1300 mAh lithium-polymer cell which gives a useful lifespan of six months between recharges. A simple 3D-printed case holds everything together and completes the clean and simple look. [Dominic] notes that it’s possible to also use the device via Matter or Thread without a lot of changes, as the ESP32-C6 can easily handle those protocols, too.

If you’re looking for a cheap, handsome keypad for your Home Assistant setup or similar, you might find this useful. We’ve explored DIY keypad entry systems before, too. If you’ve come up with some other creative way to get into your house, car, or bank vault, be sure to notify us via the tipsline.

A GUI Solution For ESP32 Web Development

June 26, 2026 by 18 Comments

These days, a lot of embedded projects feature some sort of screen, and a screen often creates a desire for a nice user interface. [Geoffrey Wells] has created a tool for developing web interfaces for the ESP32, named ESP-GenUI.

The aim was to make UI development as easy as possible for this platform. ESP-GenUI allows the creation of a website by dragging various nodes on to a canvas and linking them up to create the desired web interface. There are nodes for GPIO control, camera feeds, gauges, and all sorts of other common elements for quickly putting together dashboards and control panels. All this is done from within the browser, and the code generated by the tool can even be flashed without having to open any external tools. Alternatively, it can spit out Arduino code that you can open and flash from within the IDE. You can try the tool out yourself right here.

We’ve featured some other great resources for developing embedded user interfaces, like this highly-flexible display library for the ESP32. Feel free to espouse on your own favorite tools and techniques in the comments.

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