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.

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.

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.

[Suryansh]’s talk took in a number of drone projects which he has been involved with. The first was the creatively-named BEAVIS, or Balloon Enabled Aerial Vehicle for IoT and Sensing. This was a project that aimed to tackle one of the greatest limitations of the common multirotor drone. Namely, as [Suryansh] so elegantly puts it, they “suck when it comes to staying in the air.” This is for a very simple reason—much like the helicopter, a multirotor drone must expend energy continuously to generate lift by spinning its propellers. Conventional multirotors don’t have wings that generate lift from forward motion, and any sort of gliding or similar behavior is basically impossible. Continual energy expenditure is the only thing keeping a multirotor aloft.

The point of BEAVIS was to fix this by combining drone tech with a simple lighter-than-air balloon. It’s an interesting combination, because a multirotor drone has excellent maneuverability and agility, but terrible endurance. A lighter-than-air balloon is quite the opposite, which has excellent endurance while suffering in all other respects. The BEAVIS concept outfits a small balloon with four motors in a split-cross configuration, which allows for planar translation as well as the ability to control yaw of the craft. With all four motors mounted horizontally in the same plane, it may seem like vertical control is not possible. However, by turning on two opposing props, it’s possible to create a low-pressure region beneath the craft which tends to push it downwards. Meanwhile, if you turn all four props on in the right directions, you create a high pressure region underneath the balloon which pushes the craft up. With the balloon, it has the benefit of being able to just hang in the air without continually burning through battery power. Endurance times of well over an hour were possible with this build, compared to maybe less than ten minutes for a comparable pure multirotor.

BEAVIS was eventually developed into Janus— described as a “morphing quadrotor blimp with balloon failure resilience.” The goal was to build a craft that was viable for deployment in the real world, and that could undertake mobile ecological sensing work. The main difference to the previous design was that it would no longer solely fly as a balloon with horizontally-mounted props. Instead, Janus would feature a mechanism to allow the rotors to be positioned in the vertical axis to allow for conventional multirotor flight. This was key to allowing the craft to fly both as a lighter-than-air craft, and to survive and keep flying in the event the balloon burst or was otherwise damaged. The build was eventually deployed in Kenya to aid in ecological data collection for conservation efforts.

[Suryansh] has been involved in other drone-related projects, too. Open Gimbal was a particularly interesting effort, involving the construction of a bench-testing rig for developing small multirotor drone craft. The 3-DoF platform offered unrestricted rotational freedom, allowing for a craft to be put through its paces in a controlled way without requiring a large open  space for free flight. [Suryansh] also discusses his work with a company called Avy, which specializes in VTOL drones with a focus on emergency response roles. The company has deployed drones that use multirotor technology to launch vertically, while relying on fixed wing aerodynamic elements to extend range and improve efficiency for longer flight times. The drones feature a neat charging setup, wherein pogo pins on the fins pick up power from the metal launchpad to ensure that batteries are fully charged and the drone is ready to go at all times.

Ultimately, multirotor drones have taken on their basic form for good reason. With that said, as [Suryansh]’s talk explains, modifications to the form can have great utility when made to suit a particularly specific mission or application. If you’re developing a drone for a certain purpose, and you’re running into hard limitations, you might try thinking outside the box to make something more fitting for your goals.

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.

Thanks to [Vik Olliver] for the tip!