Looks like the Simpsons had it right again, now that an Australian radio station has been caught using an AI-generated DJ for their midday slot. Station CADA, a Sydney-based broadcaster that’s part of the Australian Radio Network, revealed that “Workdays with Thy” isn’t actually hosted by a person; rather, “Thy” is a generative AI text-to-speech system that has been on the air since November. An actual employee of the ARN finance department was used for Thy’s voice model and her headshot, which adds a bit to the creepy factor.
Space X Starship firing its many Raptor engines. The raptor pioneered the new generation of methalox. (Image: Space X)
Go back a generation of development, and excepting the shuttle-derived systems, all liquid rockets used RP-1 (aka kerosene) for their first stage. Now it seems everybody and their dog wants to fuel their rockets with methane. What happened? [Eager Space] was eager to explain in recent video, which you’ll find embedded below.
At first glance, it’s a bit of a wash: the density and specific impulses of kerolox (kerosene-oxygen) and metholox (methane-oxygen) rockets are very similar. So there’s no immediate performance improvement or volumetric disadvantage, like you would see with hydrogen fuel. Instead it is a series of small factors that all add up to a meaningful design benefit when engineering the whole system.
Methane also has the advantage of being a gas when it warms up, and rocket engines tend to be warm. So the injectors don’t have to worry about atomizing a thick liquid, and mixing fuel and oxidizer inside the engine does tend to be easier. [Eager Space] calls RP-1 “a soup”, while methane’s simpler combustion chemistry makes the simulation of these engines quicker and easier as well.
There are other factors as well, like the fact that methane is much closer in temperature to LOX, and does cost quite a bit less than RP-1, but you’ll need to watch the whole video to see how they all stack up.
We about rocketry fairly often on Hackaday, seeing projects with both liquid-fueled and solid-fueled engines. We’ve even highlighted at least one methalox rocket, way back in 2019. Our thanks to space-loving reader [Stephen Walters] for the tip. Building a rocket of your own? Let us know about it with the tip line.
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.
[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 reigns 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. Video after the break.
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.
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.
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.
[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.
