Custom Dog Door Prevents Culinary Atrocities

April 17, 2024 by Bob Baddeley 31 Comments

Riley, an 8 lb pug, has more beauty than brains, and a palate as unrefined as crude oil. While we hate criticizing others’ interests and tastes, his penchant for eating cat poop needed to stop. After a thorough exploration of a variety of options, including cat food additives that make its excrement taste worse (HOW? WHY? Clearly taste wasn’t the issue!), automatic litter boxes that stow the secretions, and pet doors that authenticate access to the room with the litter box, [Science Buddies] eventually settled on a solution that was amenable to all members of the family.

The trick was in creating a door mechanism with a blacklist of sorts rather than a whitelist. As the cat didn’t like to push the door open itself, the solution needed to have the pet door open by default. A magnet on Riley’s collar would trip a sensor attached to an Arduino that would control servos to swing the door shut immediately if he attempted to access the defecated delights. Of course safety was a consideration with the door swinging in Riley’s face.

We’ve covered a few pet screeners, including one for the same purpose that used IR sensors (but a much bigger dog also named Riley), and a flock of solutions for chickens. We’ve also seen [Science Buddies] in previous posts, so they’re not on the tips line blacklist.

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Inputs Of Interest: The Svalboard Could Be Your Salvation

February 14, 2024 by Kristina Panos 12 Comments

You know, sometimes dreams really do come true. When I told you about the DataHand keyboard almost four years ago, I never imagined I’d ever get to lay my hands on anything even remotely like it, between the original price point and the fact that they really, really hold their value. But thanks to [Morgan Venable], creator of the Svalboard, I can finally tell you what it’s like to type with your digits directionalized.

If you don’t recall, the DataHand was touted to be a total revolution in typing for RSI sufferers. It debuted in 1993 for a hefty price tag of about $1,500 — pretty far out of reach of the average consumer, but well within the budgets of the IT departments of companies who really wanted to keep their workers working. You want minimum finger travel? It doesn’t get more minimal than this concept of a d-pad plus the regular down action for each finger.

The Svalboard aims to be the new and improved solution for something that barely exists anymore, but still has a devoted following. Although the DataHand was built on a gantry and adjustable using knobs, the smallest fit possible on the thing is still rather big. Conversely, the Svalboard is fully customizable to suit any size hand and fingertip.

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Thermal Earring Tracks Body Temperature

February 13, 2024 by Kristina Panos 11 Comments

If you want to constantly measure body temperature to track things like ovulation, you usually have to wear something around your wrist or finger in the form of a smartwatch or ring. Well, what if you can’t or don’t want to adorn yourself this way? Then there’s the thermal earring.

Developed at the University of Washington, the thermal earring is quite small and unobtrusive compared to a smartwatch. Sure, it dangles, but that’s so it can measure ambient temperature for comparison’s sake.

You don’t even need to have pierced ears — the earring attaches to the lobe magnetically. And yeah, the earring can be decorated to hide the circuitry, but you know we would rock the bare boards.

The earring uses BLE to transmit readings throughout the day, and of course goes into sleep mode between transmissions to save power. Coincidentally, it runs for 28 days per charge, which is the length of the average menstrual cycle. While the earring at this time merely “shows promise” as a means of monitoring stress and ovulation, it did outperform a smartwatch at measuring skin temperature while the wearers were at rest.

This is definitely not the only pair of earrings we’ve got around here. These art deco earrings use flexible PCBs, and this pair will light up the night.

Several people at a museum exhibit about magnetism

Hands-On Museum Exhibit Brings Electromagnetism To Life

January 17, 2023 by Robin Kearey 5 Comments

Magnets, how do they work? Although the quantum mechanics behind ferromagnetism are by no means easy, a few simple experiments can give you a good grasp of how magnets attract and repel each other, and show how they interact with electric phenomena. [Niklas Roy] built an exhibit for the Technorama science museum in Switzerland that packs a bunch of such electromagnetic experiments in a single package, appropriately called the Visitors Magnet.

The exhibit consists of a big magnet-shaped enclosure that contains a variety of demonstrators that are all powered by magnets. They range from simple compasses to clever magnetic devices we find in the world around us: flip-dot displays for instance, on which you can toggle the pixels by passing a magnet over them. You can even visualize magnetic field lines by using magnetic viewing film, or turn varying fields into audio through a modified telephone receiver.

Another classic demonstrator of electromagnetism is a color CRT monitor, which here displays a video feed coming from a camera hanging directly overhead. Passing a magnet along the screen makes all kind of hypnotizing patterns and colors, amplified even more by the video feedback loop. [Niklas] also modified the picture tube with an additional coil, connected to a hand-cranked generator: this allows visitors to rotate the image on the screen by generating an AC current, neatly demonstrating the interaction between electricity and magnetism.

The Visitors Magnet is a treasure trove of big and small experiments, which might not all withstand years of use by museum guests. But that’s fine — [Niklas] designed the exhibit to be easy to maintain and repair, and expects the museum to replace worn-out experiments now and then to keep the experience fresh. He knows a thing or two about designing engaging museum exhibits, with a portfolio that includes vector image generators, graffiti robots and a huge mechanical contraption that plays musical instruments.

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DIY Magnet Handling Tool Puts An End To Placement Errors

January 14, 2023 by Donald Papp 10 Comments

I’m sure we can all agree that the worst time to find out a magnet is the wrong way around is after glue has been applied. With that in mind, [erick.siders] created the parametric Magnet Placer tool.

Color-coded tools, one for each polarity.

Picking up and placing magnets into assemblies can be an error-prone process, because magnet polarity cannot be directly identified or sensed by either sight or fingertips. This tool helps by acting a lot like a suction pickup tool — press the plunger down, and a magnet can be picked up, release the plunger, and the magnet lets go. Simple, and effective.

Since the tool is polarity-dependent (depending on which orientation the pickup magnet is mounted into the internal plunger), [erick.siders] suggests printing two tools and color-coding them. That way, one can choose the right tool based on the situation and be confident that the magnets are right-side-up, every time.

The tools use a long metric bolt, a magnet, and a spring, but none of those parts are particularly critical. We also love the way that the end result has no gaps or openings into the moving parts, which means nothing can get caught on or inside anything during use or storage.

It’s a parametric design and the CAD files (in both Fusion 360 and STEP flavors) are provided, so modification should be a breeze. And if you happen to be using PrusaSlicer, remember you can now drop STEP format files directly in for slicing.

Hanging Christmas Lights With No Ladder And No Fuss

December 3, 2022 by Lewin Day 25 Comments

Getting up on a ladder to hang Christmas lights is a great way to hurt yourself if you’re not careful, and winter conditions only add to the peril. One enterprising hacker has whipped up a neat way to avoid ladders entirely, by hanging their lights while planted safely on the ground.

The build uses hefty magnets and triangle eye bolts, attached at regular intervals to the string of Christmas lights. The magnets are used to hold the lights to metal roof siding, while the hooks allow the lights to be lifted into place using a hook on a large extendable pole. Washers, spacers, and screws are used to attach the magnets and hooks to the lights.

For a layout that follows the lines of a simple peaked roof, this hack works great. For more complicated installations, you might still have to climb up a ladder. We’ve featured great primers on getting started with advanced Christmas light displays before, if you’re looking to up your game.

Meanwhile, no matter how much you enjoy seasonal decoration brinkmanship, don’t even think about watching Deck the Halls (2006). Danny Devito has saved a lot of films, but he couldn’t save this. Happy holidays!

Digital Hourglass Counts Down The Seconds

October 26, 2022 by Adam Fabio 20 Comments

If someone asked you to build a digital hourglass, what would your design look like? [BitBlt_Korry] took on that challenge, creating a functional art piece that hits it right on the nose: an hourglass with a digital display.

Iron filings fall between two pieces of plexiglass while ghostly numbers appear, counting down 30 seconds. Just as quickly as they appear, the numbers disappear – dropping down to the bottom of the enclosure. Each second is punctuated by what might be the loudest clock tick we’ve ever heard.

Of course, it’s not all magic. The hourglass is controlled by a Raspberry Pi Pico running code in MicroPython. The pico drives a series of transistors, which in turn are used to control 14 solenoids. The solenoids serve double duty — first, they move pieces of flat “fridge magnet” material close enough to attract iron filings. Their second duty is of course provide a clock tick that will definitely get your attention.

Tilt sensors are the user input to the hourglass, letting the Pi Pico know which end is up when it’s time to start a new 30-second countdown.

[BitBlt_Korry] mentions that the hardest part of the project was setting the screws at the top and bottom of the hourglass to get the perfect uniform flow of iron filings.

[BitBlt_Korry] calls his creation “「時場(じば)」”. Google translates this to “Jiba”, which means “magnetic field”. We’re not native speakers, but we’re guessing there is a double meaning there.

This isn’t the first time we’ve seen humble iron filings stand up and dance at our command. If iron dust is too dry a topic, we’ve got plenty of ferrofluid projects as well!

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