When you really love your pawed, feathered, or scaled friends, you build projects for them. (Well, anyway, that’s what’s happened to us.) For the 2025 Pet Hacks Challenge, we asked you to share your favorite pet-related hacks, and you all delivered. So without further ado, here are our favorites, as well as the picks-of-the-litter that qualified for three $150 DigiKey gift certificates. Spoiler alert: it was a clean sweep for team cat.

The Top Three

[Andrea Favero]’s CAT AT THE DOOR project (his caps, not ours) packs more tech than strictly necessary, and our judges loved it. When the cat approaches, a radar detects it, a BLE collar identifies the particular cat, and a LoRA radio notifies the human on a beautiful e-ink display with a sufficiently loud beeper. Your job, then, is to open the door. This project has standout build instructions, and even if you’re a dog person, you’ll want to read them if you’re using any of these technologies in a build of your own.

Foxy and Layla are two cats on two different diets. One has prescription food that unfortunately isn’t as tasty as the regular stuff, but that doesn’t mean she can just mompf up the other cat’s chow. The solution? Computer vision! [Joe Mattioni]’s Cat Bowl Monitor hacks a commercial cat feeder to operate via an Android app running on an old cell phone. [Joe] trained the image recognition algorithm specifically on his two cats, which helps reliability greatly. Like the previous winner, the documentation is great, and it’s a sweet application of real-time image classification and a nice reuse of an oldish cellphone. Kudos!

And finally, [rkramer]’s Cat Valve is a one-way cat airlock. Since “Bad Kitty” likes to go out hunting at night, and [rkramer] doesn’t like having live trophies continually brought back into the house, a sliding door lets the cat out, but then closes behind. A webcam and a Raspberry Pi lets the human decide if the cat gets to come back in or not, relying on HI (Human Intelligence) for the image processing. This isn’t inhumane: the cat isn’t stuck outside, but merely in the cellar. No mention of how [rkramer] gets the traumatized rats out of his cellar, but we imagine there’ll be a hack for that as well.

Congrats to you three! We’ll be getting in touch with you soon to get your $150 DigiKey spending spree.

Honorable Mentions

The “Pet Safety” honorable mention category was created to honor those hacks that help promote pet health and safety. Nothing fit that bill as well as [donutsorelse]’s Chicken Guardian, which uses computer vision to detect various predators and scare them away with a loud voice recording. (We’re not sure if that’s entertaining or effective.) [Saren Tasciyan]’s Dog bed is also a dog scale that does just what it says, and we imagine that it’s a huge quality of life improvement for both the Bernese and her owners. And finally, [methodicalmaker_]’s IoT Cat Treat Dispenser + Treadmill for Weight Loss is a paradox: rewarding a cat with food for getting on a treadmill to lose weight. Time will tell if the dosages can be calibrated just right.

In the “Home Alone” category, we wanted to see remote pet-care ideas. Of course, there was a vacation fish feeder, in the form of [Coders Cafe]’s Aquassist, which we really liked for the phone app – it’s a simple build that looks great. Further from the beaten path, [kasik]’s TinyML meets dog training is a cool experiment in machine learning that also feeds and distracts the dog from barking at the door, even when [kasik] is out.

“Playful Pets” was for the goofy, fun, pet hacks, and the hamsters have won it. [Giulio Pons] brought us Ruby’s Connected Hamster Wheel, which tracked his hamster’s mileage on the wheel at night for two years running, and [Roni Bandini]’s Wall Street hamster project lets Milstein buy and sell stonks. Hilarious, and hopefully not too financially painful.

And finally, the “Cyborg Pets” category just has to go to Fytó, which basically gamifies taking care of a plant. There was intense debate about whether a plant could be a pet, but what’s more cyborg than a living Tamagotchi?

Thanks!

Thanks to everyone who entered! It was awesome to see your efforts on behalf of our animal friends. And if you didn’t get to enter because you just don’t have a pet, check back in with us on Thursday, when our next challenge begins.

If you’re designing a new jet-powered airplane, one of the design considerations is the number of jet engines you will put on it. Over the course of history we have seen everywhere from a single engine, all the way up to four and beyond, with today airliners usually having two engines aside from the Boeing 747 and Airbus A380 has been largely phased out. Yet for a long time airliners featured three engines, which raises the question of why this configuration has mostly vanished now. This is the topic of a recent YouTube video by [Plane Curious], embedded below.

The Boeing 727, DC-10 and L-1011 TriStar are probably among the most well-known trijets, all being unveiled around the same time. The main reason for this was actually regulatory, as twin-engine designs were thought to be too unsafe for long flights across oceans, while quad-jet designs were too fuel-hungry. This remained the situation until newer jet engine designs that were more reliable and powerful, leading to new safety standards (ETOPS) that allowed twinjets to fly these longer routes as well. Consequently, the last passenger trijet – an MD-11 KLM flight – touched down in 2014.

Along with the engineering and maintenance challenges that come with having a tail-mounted jet engine, the era of trijets seem to have firmly come to an end, at least for commercial airliners.

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hackaday.com/2025/06/24/why-tr…

Are you passionate about European policy and security? Don’t miss the chance to participate in the Pirate Academy, running from September to November 2025. Thirty selected candidates will take part in online sessions focused on key challenges and problem areas, where they will gain a deeper understanding of how European institutions function. Ten of them will have the unique opportunity to experience the process firsthand in Brussels in winter 2025, alongside MEP Markéta Gregorová. The entire course is hosted by MEP Gregorová and her political group, the Greens/EFA.

Curious about how complex problems are negotiated in the European Parliament? Then keep reading. The workings of the European institutions are intricate, designed to ensure democratic processes and representation for all member states. The issues they tackle often have global implications. Even Members of the European Parliament (MEPs) sometimes struggle to stay on top of all the legislation and world developments — that’s why they rely on policy advisors. Through the Pirate Academy, you’ll have the chance to step into this role and experience it for yourself.

To negotiate European legislation effectively, it’s essential to understand how the European Commission and the European Parliament function — including who holds which responsibilities and powers. This is one of the core topics covered in detail during the Online Pirate Academy. Want to get a behind-the-scenes look at how legislation is negotiated? Wondering if you need any special superpowers to do it? If so, you’re in the right place — don’t miss this opportunity. Apply for the Online Pirate Academy here.

In today’s turbulent times, we face many crises that shape global politics. The European Parliament plays a key role in addressing the most pressing issues of our time — from the war in Ukraine and climate change to EU–China relations and more. By joining the Pirate Academy, you’ll gain insight into what it means to influence and shape policy — and the consequences that come with it. The course combines an in-depth look at the daily operations of the European Parliament with hands-on, experiential learning.
The post European Pirate Academy: learn everything about negotiating EU legislation first appeared on European Pirate Party.

It’s an inconvenient fact that most of Earth’s largesse of useful minerals is locked up in, under, and around a lot of rock. Our little world condensed out of the remnants of stars whose death throes cooked up almost every element in the periodic table, and in the intervening billions of years, those elements have sorted themselves out into deposits that range from the easily accessed, lying-about-on-the-ground types to those buried deep in the crust, or worse yet, those that are distributed so sparsely within a mineral matrix that it takes harvesting megatonnes of material to find just a few kilos of the stuff.

Whatever the substance of our desires, and no matter how it is associated with the rocks and minerals below our feet, almost every mining and refining effort starts with wresting vast quantities of rock from the Earth’s crust. And the easiest, cheapest, and fastest way to do that most often involves blasting. In a very real way, explosives make the world work, for without them, the minerals we need to do almost anything would be prohibitively expensive to produce, if it were possible at all. And understanding the chemistry, physics, and engineering behind blasting operations is key to understanding almost everything about Mining and Refining.

First, We Drill

For almost all of the time that we’ve been mining minerals, making big rocks into smaller rocks has been the work of strong backs and arms supplemented by the mechanical advantage of tools like picks, pry bars, and shovels. The historical record shows that early miners tried to reduce this effort with clever applications of low-energy physics, such as jamming wooden plugs into holes in the rocks and soaking them with liquid to swell the wood and exert enough force to fracture the rock, or by heating the rock with bonfires and then flooding with cold water to create thermal stress fractures. These methods, while effective, only traded effort for time, and only worked for certain types of rock.

Mining productivity got a much-needed boost in 1627 with the first recorded use of gunpowder for blasting at a gold mine in what is now Slovakia. Boreholes were stuffed with powder that was ignited by a fuse made from a powder-filled reed. The result was a pile of rubble that would have taken weeks to produce by hand, and while the speed with which the explosion achieved that result was probably much welcomed by the miners, in reality, it only shifted their efforts to drilling the boreholes, which generally took a five-man crew using sledgehammers and striker bars to pound deep holes into the rock. Replacing that manual effort with mechanical drilling was the next big advance, but it would have to wait until the Industrial Revolution harnessed the power of steam to run drills capable of boring deep holes in rock quickly and with much smaller crews.

The basic principles of rock drilling developed in the 19th century, such as rapidly spinning a hardened steel bit while exerting tremendous down-pressure and high-impulse percussion, remain applicable today, although with advancements like synthetic diamond tooling and better methods of power transmission. Modern drills for open-cast mining fall into two broad categories: overburden drills, which typically drill straight down or at a slight angle to vertical and can drill large-diameter holes over 100 meters deep, and quarry drills, which are smaller and more maneuverable rigs that can drill at any angle, even horizontally. Most drill rigs are track-driven for greater mobility over rubble-strewn surfaces, and are equipped with soundproofed, air-conditioned cabs with safety cages to protect the operator. Automation is a big part of modern rigs, with automatic leveling systems, tool changers that can select the proper bit for the rock type, and fully automated drill chain handling, including addition of drill rod to push the bit deeper into the rock. Many drill rigs even have semi-autonomous operation, where a single operator can control a fleet of rigs from a single remote control console.

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Proper Prior Planning

While the use of explosives seems brutally chaotic and indiscriminate, it’s really the exact opposite. Each of the so-called “shots” in a blasting operation is a carefully controlled, highly engineered event designed to move material in a specific direction with the desired degree of fracturing, all while ensuring the safety of the miners and the facility.

To accomplish this, a blasting plan is put together by a mining engineer. The blasting plan takes into account the mechanical characteristics of the rock, the location and direction of any pre-existing fractures or faults, and proximity to any structures or hazards. Engineers also need to account for the equipment used for mucking, which is the process of removing blasted material for further processing. For instance, a wheeled loader operating on the same level, or bench, that the blasting took place on needs a different size and shape of rubble pile than an excavator or dragline operating from the bench above. The capabilities of the rock crushing machinery that’s going to be used to process the rubble also have to be accounted for in the blasting plan.

Most blasting plans define a matrix of drill holes with very specific spacing, generally with long rows and short columns. The drill plan specifies the diameter of each hole along with its depth, which usually goes a little beyond the distance to the next bench down. The mining engineer also specifies a stem height for the hole, which leaves room on top of the explosives to backfill the hole with drill tailings or gravel.

Prills and Oil

Once the drill holes are complete and inspected, charging the holes with explosives can begin. The type of blasting agents to be used is determined by the blasting plan, but in most cases, the agent of choice is ANFO, or ammonium nitrate and fuel oil. The ammonium nitrate, which contains 60% oxygen by weight, serves as an oxidizer for the combustion of the long-chain alkanes in the fuel oil. The ideal mix is 94% ammonium nitrate to 6% fuel oil.
Filling holes with ammonium nitrate at a blasting site. Hopper trucks like this are often used to carry prilled ammonium nitrate. Some trucks also have a tank for the fuel oil that’s added to the ammonium nitrate to make ANFO. Credit: Old Bear Photo, via Adobe Stock.
How the ANFO is added to the hole depends on conditions. For holes where groundwater is not a problem, ammonium nitrate in the form of small porous beads or prills, is poured down the hole and lightly tamped to remove any voids or air spaces before the correct amount of fuel oil is added. For wet conditions, an ammonium nitrate emulsion will be used instead. This is just a solution of ammonium nitrate in water with emulsifiers added to allow the fuel oil to mix with the oxidizer.

ANFO is classified as a tertiary explosive, meaning it is insensitive to shock and requires a booster to detonate. The booster charge is generally a secondary explosive such as PETN, or pentaerythritol tetranitrate, a powerful explosive that’s chemically similar to nitroglycerine but is much more stable. PETN comes in a number of forms, with cardboard cylinders like oversized fireworks or a PETN-laced gel stuffed into a plastic tube that looks like a sausage being the most common.
Electrically operated blasting caps marked with their built-in 425 ms delay. These will easily blow your hand clean off. Source: Timo Halén, CC BY-SA 2.5.
Being a secondary explosive, the booster charge needs a fairly strong shock to detonate. This shock is provided by a blasting cap or detonator, which is a small, multi-stage pyrotechnic device. These are generally in the form of a small brass or copper tube filled with a layer of primary explosive such as lead azide or fulminate of mercury, along with a small amount of secondary explosive such as PETN. The primary charge is in physical contact with an initiator of some sort, either a bridge wire in the case of electrically initiated detonators, or more commonly, a shock tube. Shock tubes are thin-walled plastic tubing with a layer of reactive explosive powder on the inner wall. The explosive powder is engineered to detonate down the tube at around 2,000 m/s, carrying a shock wave into the detonator at a known rate, which makes propagation delays easy to calculate.

Timing is critical to the blasting plan. If the explosives in each hole were to all detonate at the same time, there wouldn’t be anywhere for the displaced material to go. To prevent that, mining engineers build delays into the blasting plan so that some charges, typically the ones closest to the free face of the bench, go off a fraction of a second before the charges behind them, freeing up space for the displaced material to move into. Delays are either built into the initiator as a layer of pyrotechnic material that burns at a known rate between the initiator and the primary charge, or by using surface delays, which are devices with fixed delays that connect the initiator down the hole to the rest of the charges that will make up the shot. Lately, electronic detonators have been introduced, which have microcontrollers built in. These detonators are addressable and can have a specific delay programmed in the field, making it easier to program the delays needed for the entire shot. Electronic detonators also require a specific code to be transmitted to detonate, which reduces the chance of injury or misuse that lost or stolen electrical blasting caps present. This was enough of a problem that a series of public service films on the dangers of playing with blasting caps appeared regularly from the 1950s through the 1970s.

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“Fire in the Hole!”

When all the holes are charged and properly stemmed, the blasting crew makes the final connections on the surface. Connections can be made with wires for electrical and electronic detonators, or with shock tubes for non-electric detonators. Sometimes, detonating cord is used to make the surface connections between holes. Det cord is similar to shock tube but generally looks like woven nylon cord. It also detonates at a much faster rate (6,500 m/s) than shock tube thanks to being filled with PETN or a similar high-velocity explosive.

Once the final connections to the blasting controller are made and tested, the area is secured with all personnel and equipment removed. A series of increasingly urgent warnings are sounded on sirens or horns as the blast approaches, to alert personnel to the danger. The blaster initiates the shot at the controller, which sends the signal down trunklines and into any surface delays before being transmitted to the detonators via their downlines. The relatively weak shock wave from the detonator propagates into the booster charge, which imparts enough energy into the ANFO to start detonation of the main charge.

The ANFO rapidly decomposes into a mixture of hot gases, including carbon dioxide, nitrogen, and water vapor. The shock wave pulverizes the rock surrounding the borehole and rapidly propagates into the surrounding rock, exerting tremendous compressive force. The shock wave continues to propagate until it meets a natural crack or the interface between rock and air at the free face of the shot. These impedance discontinuities reflect the compressive wave and turn it into a tensile wave, and since rock is generally much weaker in tension than compression, this is where the real destruction begins.

The reflected tensile forces break the rock along natural or newly formed cracks, creating voids that are filled with the rapidly expanding gases from the burning ANFO. The gases force these cracks apart, providing the heave needed to move rock fragments into the voids created by the initial shock wave. The shot progresses at the set delay intervals between holes, with the initial shock from new explosions creating more fractures deeper into the rock face and more expanding gas to move the fragments into the space created by earlier explosions. Depending on how many holes are in the shot and how long the delays are, the entire thing can be over in just a few seconds, or it could go on for quite some time, as it does in this world-record blast at a coal mine in Queensland in 2019, which used 3,899 boreholes packed with 2,194 tonnes of ANFO to move 4.7 million cubic meters of material in just 16 seconds.

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There’s still much for the blasting crew to do once the shot is done. As the dust settles, safety crews use monitoring equipment to ensure any hazardous blasting gases have dispersed before sending in crews to look for any misfires. Misfires can result in a reshoot, where crews hook up a fresh initiator and try to detonate the booster charge again. If the charge won’t fire, it can be carefully extracted from the rubble pile with non-sparking tools and soaked in water to inactivate it.

hackaday.com/2025/06/24/mining…

On 24 June 2025, EDRi, Access Now and other civil society organisations sent a second letter to the European Commission, urging it to reassess Israel’s data protection adequacy status under the GDPR. The letter outlines six categories of concerns linking Israel’s data practices to escalating human rights violations in Gaza and the West Bank.

The post Data flows and digital repression: Civil society urges EU to reassess Israel’s adequacy status appeared first on European Digital Rights (EDRi).

With Budapest Pride set to take place on June 28, 2025, EDRi and 46 organisation are urging the European Commission to defend fundamental rights in Hungary so that Pride organisers and participants can safely exercise their right to peaceful assembly and freedom of expression.

The post OPEN LETTER: The European Commission must act now to defend fundamental rights in Hungary appeared first on European Digital Rights (EDRi).