Quick And Easy Digital Stethoscope Keeps Tabs On Cat

For all their education, medical practitioners sometimes forget that what’s old hat to them is new territory for their patients. [David Revoy] learned that when a recent visit to the veterinarian resulted in the need to monitor his cat’s pulse rate at home, a task that he found difficult enough that he hacked together this digital cat stethoscope.

Never fear; [David] makes it clear that his fur-baby [Geuloush] is fine, although the gel needed for an echocardiogram likely left the cat permanently miffed. With a normal feline heart rate in the 140s, [David] found it hard to get an accurate pulse by palpation, so he bought a cheap stethoscope and a basic lavalier USB microphone. Getting them together was as easy as cutting the silicone tubing from the stethoscope head and sticking the microphone into it.

The tricky part, of course, would be getting [Geuloush] to cooperate. That took some doing, but soon enough [David] had a clean recording to visualize in an audio editor. From there it’s just a simple matter of counting up the peaks and figuring out the beats per second. It probably wouldn’t be too hard to build a small counter using a microcontroller so he doesn’t have to count on the cat napping near his PC, but in our experience, keyboards are pretty good cat attractants.

This is one of those nice, quick hacks whose simplicity belies their impact. It’s certainly not as fancy as some of the smart stethoscopes we’ve seen, but it doesn’t need to be.

Thanks to [Spooner] for the tip.

VESC Mods Made Via Vibe Coding

[David Bloomfield] wanted to make some tweaks to an embedded system, but didn’t quite have the requisite skills. He decided to see if vibe coding could help.

[David]’s goal was simple. To take the VESC Telemetry Display created by [Lukas Janky] and add some tweaks of his own. He wanted to add more colors to the display, while changing the format of the displayed data and tweaking how it gets saved to EEPROM. The only problem was that [David] wasn’t experienced in coding at all, let alone for embedded systems like the Arduino Nano. His solution? Hand over the reins to a large language model. [David] used Gemini 2.5 Pro to make the changes, and by and large, got the tweaks made that he was looking for.

There are risks here, of course. If you’re working on an embedded system, whatever you’re doing could have real world consequences. Meanwhile, if you’re relying on the AI to generate the code and you don’t fully understand it yourself… well, the possibilities are obvious. It pays to know what you’re doing at the end of the day. In this case, it’s hard to imagine much going wrong with a simple telemetry display, but it bears considering the risks whatever you’re doing.

We’ve talked about the advent of vibe coding before, too, with [Jenny List] exploring this nascent phenomenon. Expect it to remain a topic of controversy in coding circles for some time.

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Save Cells From The Landfill, Get A Power Bank For Your Troubles

A hefty portable power bank is a handy thing to DIY, but one needs to get their hands on a number of matching lithium-ion cells to make it happen. [Chris Doel] points out an easy solution: salvage them from disposable vapes and build a solid 35-cell power bank. Single use devices? Not on his watch!

[Chris] has made it his mission to build useful things like power banks out of cells harvested from disposable vapes. He finds them — hundreds of them — on the ground or in bins (especially after events like music festivals) but has also found that vape shops are more than happy to hand them over if asked. Extracting usable cells is most of the work, and [Chris] has refined safely doing so into an art.

Disposable vapes are in all shapes and sizes, but cells inside are fairly similar.

Many different vapes use the same cell types on the inside, and once one has 35 identical cells in healthy condition it’s just a matter of using a compatible 3D-printed enclosure with two PCBs to connect the cells, and a pre-made board handles the power bank functionality, including recharging.

We’d like to highlight a few design features that strike us as interesting. One is the three little bendy “wings” that cradle each cell, ensuring cells are centered and held snugly even if they aren’t exactly the right size.  Another is the use of spring terminals to avoid the need to solder to individual cells. The PCBs themselves also double as cell balancers, providing a way to passively balance all 35 cells and ensure they are at the same voltage level during initial construction. After the cells are confirmed to be balanced, a solder jumper near each terminal is closed to bypass that functionality for final assembly.

The result is a hefty power bank that can power just about anything, and maybe the best part is that it can be opened and individual cells swapped out as they reach the end of their useful life. With an estimated 260 million disposable vapes thrown in the trash every year in the UK alone, each one containing a rechargeable lithium-ion cell, there’s no shortage of cells for an enterprising hacker willing to put in a bit of work.

Power banks not your thing? [Chris] has also created a DIY e-bike battery using salvaged cells, and that’s a money saver right there.

Learn all about it in the video, embedded below. And if you find yourself curious about what exactly goes on in a lithium-ion battery, let our own Arya Voronova tell you all about it.

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Deep Dive On Panel Making

It is easier than ever to produce projects with nice enclosures thanks to 3D printing and laser cutting. However, for a polished look, you also need a labeled front panel. We’ve looked at several methods for doing that in the past, but we enjoyed [Accidental Science’s] video showing his method for making laminated panels.

His first step is to draw the panel in Inkscape, and he has some interesting tips for getting the most out of the program. He makes a few prints and laminates one of them. The other is a drill guide. You use the drill guide to make openings in the panel, which could be aluminum, steel, plastic, or whatever material you want to work in.

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Creating An Electronic Board For Catan-Compatible Shenanigans

[Sean Boyce] has been busy building board games. Specifically, an electronic strategy boardgame that is miraculously also compatible with Settlers of Catan.

[Sean’s] game is called Calculus. It’s about mining asteroids and bartering. You’re playing as a corporation attempting to mine the asteroid against up to three others doing the same. Do a good job of exploiting the space-based resource, and you’ll win the game.

Calculus is played on a board made out of PCBs. A Xiao RP2040 microcontroller board on the small PCB in the center of the playfield is responsible for running the show. It controls a whole ton of seven-segment displays and RGB LEDs across multiple PCBs that make up the gameboard. The lights and displays help players track the game state as they vie for asteroid mining supremacy. Amusingly, by virtue of its geometry and some smart design choices, you can also use [Sean]’s board to play Settlers of Catan. He’s even designed a smaller, cheaper travel version, too.

We do see some interesting board games around these parts, because hackers and makers are just that creative. If you’ve got your own board game hacks or builds in the works, don’t hesitate to let us know!

Another Coil Winder Project

If you build electronics, you will eventually need a coil. If you spend any time winding one, you are almost guaranteed to think about building a coil winder. Maybe that’s why so many people do. [Jtacha] did a take on the project, and we were impressed — it looks great.

The device has a keypad and an LCD. You can enter a number of turns or the desired inductance. It also lets you wind at an angle. So it is suitable for RF coils, Tesla coils, or any other reason you need a coil.

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YKK’s Self-Propelled Zipper: Less Crazy Than It Seems

The self-propelled zip fastener uses a worm gear to propel itself along the teeth. (Credit: YKK)
The self-propelled zip fastener uses a worm gear to propel itself along the teeth. (Credit: YKK)

At first glance the very idea of a zipper that unzips and zips up by itself seems somewhat ridiculous. After all, these contraptions are mostly used on pieces of clothing and gear where handling a zipper isn’t really sped up by having an electric motor sluggishly move through the rows of interlocking teeth. Of course, that’s not the goal of YKK, which is the world’s largest manufacturer of zip fasteners. The demonstrated prototype (original PR in Japanese) shows this quite clearly, with a big tent and equally big zipper that you’d be hard pressed to zip up by hand.

The basic application is thus more in industrial applications and similar, with one of the videos, embedded below, showing a large ‘air tent’ being zipped up automatically after demonstrating why for a human worker this would be an arduous task. While this prototype appears to be externally powered, adding a battery or such could make it fully wireless and potentially a real timesaver when setting up large structures such as these. Assuming the battery isn’t flat, of course.

It might conceivably be possible to miniaturize this technology to the point where it’d ensure that no fly is ever left unzipped, and school kids can show off their new self-zipping jacket to their friends. This would of course have to come with serious safety considerations, as anyone who has ever had a bit of their flesh caught in a zipper can attest to.

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