Low-Resolution Fluid Simulation On An ESP32

February 28, 2025 by Lewin Day 2 Comments

Fluid simulations are a key tool in fields from aerospace to motorsports and even civil engineering. They can be three-dimensional and complicated and often run on supercomputer clusters bigger than your house. However, you can also do simple two-dimensional fluid simulations on very simple hardware, as [mircemk] demonstrates.

This build is almost like a simple toy that displays particles rolling around and tumbling as you turn it one way or the other. Behind the scenes, an ESP32 is running the show, simulating a group of particles responding to gravity in a fluid-like manner. The microcontroller is hooked up with an 3-axis gyroscope and accelerometer, which it uses to track motion and influence the motion of the particles in turn. The results of the simple fluid simulation are displayed on a screen made up of a 16 x 16 matrix of WS2812B addressable RGB LEDs, which add enough color to make the build suitably mesmerizing.

There’s something compelling about turning the display and watching the particles tumble and flow, particularly when they’re all set to different colors. [mircemk] also gave the build the ability to operate in several different modes, running “sand,” “liquid” and “gas” simulations and with dynamic coloring to boot.

We’ve seen some great videos from [mircemk] before, too, like this sensitive metal detector rig. Continue reading “Low-Resolution Fluid Simulation On An ESP32” →

Tech In Plain Sight: Shopping Cart Locks

February 28, 2025 by Al Williams 48 Comments

Shopping carts are surprisingly expensive. Prices range up to about $300 for a cart, which may seem like a lot, but they have to be pretty rugged and are made to work for decades. Plastic carts are cheaper, but not by much.

And carts have a way of vanishing. We’ve seen estimates that cart theft costs hundreds of millions of dollars worldwide annually. To stem the tide, stores sometimes pay a reward to people to round up carts off the street and return them to the store — it’s cheaper than buying a new one. That led [Elmer Isaacks] to patent a solution to this problem in 1968.

The [Isaacks] system used lots of magnets. A cart leaving the store had a brake that would be armed by running over a magnet. Customers were expected to follow a path surrounded by magnets to prevent the brake from engaging. If you left the track, a rod passing through the wheel locked it.

A third magnet would disarm the brake when you entered the store again. This is clever, but it has several problems. First, you have to insert magnets all over the place. Second, if someone knows how the system works, a simple magnet will hold the brake off no matter what. Continue reading “Tech In Plain Sight: Shopping Cart Locks” →

Hackaday Podcast Episode 310: Cyanotypes, Cyberdecks, And The Compass CNC

February 28, 2025 by Kristina Panos 4 Comments

This week, Hackaday’s Elliot Williams and Kristina Panos met up in a secret location with snacks to bring you the latest news, mystery sound, and of course, a big bunch of hacks from the previous week.

First up in the news, and there’s a lot of it: we announced the Hackaday Europe 2025 workshops and a few more speakers, though the big keynote announcement is still to come. In case you missed it, KiCad 9 moved up into the pro league, and finally, we’re hiring, so come join us in the dungeon.

On What’s That Sound, Kristina didn’t get close at all, but at least had a guess this time. That’s okay, though, because nobody got it right! We’re still giving a t-shirt away to [Dakota], though, probably because Elliot has a thing for using random number generators.

Then it’s on to the hacks and such beginning with a beautiful handheld compass CNC and cyanotype prints made with resin printer’s UV light. After that, we take a look at open-source random numbers, a 3D-printed instant camera, and a couple of really cool cyberdecks. Finally, we discuss whether DOOM is doomed as the port of choice in this day and age, and kvetch about keyboards.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download in DRM-free MP3 and savor at your leisure.

Continue reading “Hackaday Podcast Episode 310: Cyanotypes, Cyberdecks, And The Compass CNC” →

Lost Foam Aluminium Alloy Casting

February 28, 2025 by Dave Rowntree 21 Comments

[Kelly Coffield] makes intake manifolds for old Ford throttle bodies for fun, demonstrating an excellent technique for making such things in the small shop. The mould patterns are CNC machined from a solid polystyrene block, with all the necessary gates to feed the aluminium into the mould. The principle is to introduce aluminium from a large central runner into the mould structure, which feeds the gates into the mould parts. The various foam mould components are then glued with an extra brace bar at the bottom to strengthen it.

The complete structure is then sprayed with surfactant (just plain old soapy water) and dip-coated in a refractory slurry. The surfactant adjusts the coating’s surface tension, preventing bubbles from forming and ruining the surface quality produced by this critical coating step.

Once a satisfactory coating has been applied and hardened, the structure is placed inside a moulding pan fitted with a pneumatic turbine vibrator, to allow sand to be introduced. The vibrations ease the flow of sand into all the nooks and crannies, fully supporting the delicate mould structure against the weight of the metal, and gases produced as the foam burns away. A neat offset pouring cup is then added to the top of the structure and packed in with more sand to stabilise it. It’s a simple setup that can easily be replicated in any hackerspace or backyard for those motivated enough. [Kelly] is using A356 aluminium alloy, but there’s no reason this technique won’t work for other metals.

It was amusing to see [Kelly] demould by just dumping out the whole stack onto the drive and throwing the extracted casting into a snow bank after quenching. We might as well use all that free Midwest winter cooling capacity! After returning to the shop, [Kelly] would typically perform any needed adjustments, such as improving flatness in the press, while the part was in the ‘as cast temper’ condition. We’ll gloss over the admission of cutting the gates off on the table saw! After these adjustments, the part is artificially aged to a T5-like specification, to give it its final strength and machinability properties. There are plenty more videos on this process on the channel, which is well worth a look.

Aluminium casting is nothing new here, here’s a simple way to cast using a 3D printed pattern. But beware, casting aluminum can be hazardous, it does like to burn.

Continue reading “Lost Foam Aluminium Alloy Casting” →

This Week In Security: Malicious Themes, Crypto Heists, And Wallbleed

February 28, 2025 by Jonathan Bennett 13 Comments

It’s usually not a good sign when your downloaded theme contains obfuscated code. Yes, we’re talking about the very popular Material Theme for VSCode. This one has a bit of a convoluted history. One of the authors wanted to make some money from all those downloads. The original Material Theme was yanked from the VSCode store, the source code (improperly) re-licensed as closed source, and replaced with freemium versions. And this week, those freemium versions have been pulled by Microsoft for containing malware.
Continue reading “This Week In Security: Malicious Themes, Crypto Heists, And Wallbleed” →

Gonzo Film Making With The Raspberry Pi

February 28, 2025 by Lewin Day 8 Comments

Gonzo journalism has been a hip thing since the 1970s or so, a way of covering a story in a compelling format with more subjectivity and less objectivity. The style has since been applied to all sorts of media, including film—and indeed, the makers of the Gonzo Pi.

The Gonzo Pi is a camera with an open source design, yes, but it’s also a lot more than that. It’s intended to be an entire platform for film-making, all in the one housing. Camera-wise, the design combines a Raspberry Pi with the requisite first-party High Quality Camera, and warps it up in a 3D printed housing. You can build it up with a viewfinder and whatever old-school C-mount or 8 mm film lenses you can lay your hands on.

Beyond that, there’s an editing platform baked in to the device. It’s not unlike the tools in so many social media apps these days. The idea of the Gonzo Pi is that rather than shooting a whole ton of footage and takes and poring over them in great detail later, instead, you run and gun with the device and edit as you go. You can shoot retakes as you need, and even dub in more audio as necessary as you compose your film on the hoof. It’s intended to change the way you make films by virtue of its unique compositional paradigm.

We’ve featured some neat homebrew cameras before, to be sure, but none that quite put the edit suite right in the box.

Continue reading “Gonzo Film Making With The Raspberry Pi” →

Copying Commodore Data Tapes, 40 Years Late

February 28, 2025 by Bryan Cockfield 41 Comments

Unless you handle the backups for a large corporation, bank, or government entity, you likely haven’t stored much data to tape recently. But magnetic storage used to be fairly mainstream back in the 1980s for all kinds of computer programs. Plenty of computers used standard cassette tapes for this too but you couldn’t just copy them with standard audio equipment. You’d need something like this 1560 datasette from [Jan].

The core problem with using Hi-Fi equipment to copy tapes storing data instead of audio is that data tapes need to be much more precise in order to avoid losses that might not be noticeable in an audio recording. In the 80s computer companies like Commodore built tape drives specifically for their computers, so [Jan]’s project uses two of these 1530 drives to build this “1560” datasette. (No working 1530 hardware was harmed in this build.) An inverter circuit in one tape deck is used to provide the signal to write the data to the other tape, reliably copying data from these data tapes in a way Hi-Fi never could.

[Jan] does lament not having something like this back in the 80s when the Commodore was in its heyday, but there’s still a dedicated retrocomputing scene for these machines that will get plenty of use out of projects like this. If you need to go the other direction in time, there are also interfaces that allow data tapes from old Commodores to be read by modern computers with USB.

Continue reading “Copying Commodore Data Tapes, 40 Years Late” →