Building A Diet Coke Button

December 20, 2024 by Lewin Day 15 Comments

[mars91] had an interesting problem to solve—his girlfriend often requested Diet Coke, but yelling for one across the apartment was frustrating and impractical. A dedicated Diet Coke button seemed like the perfect solution, so that’s precisely what he built.

The Diet Coke Button is a relatively simple device. A small silver push-button activates an Adafruit Feather M0 to send out a signal via its RFM95 LoRa radio. That signal is picked up by the receiver device, which runs on an ESP32. It’s got an RFM95 LoRa module, which receives signals from the button and sounds an alarm to indicate the request for a Diet Coke. The ESP32 also hosts a basic website which allows Diet Coke requests to be submitted via the web, as well as general submissions of a textual nature. The latter are displayed on a small OLED display. If you’re feeling bold, you can even set up the ESP32 to be accessible from the outside Internet, with [mars91] explaining how to do so using a Cloudflare tunnel for your own protection.

The only problem is that delivering the Diet Coke is still something you have to do by hand. Perhaps a future upgrade would involve some kind of small apartment-spanning railway for the delivery of ice-cold cans to designated stations.

It’s a unique project, and one that recalls us of an interesting talk about a different type of call button.

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Hackaday Podcast Episode 301: Hacking NVMe Into Raspberry Pi, Lighting LEDs With Microwaves, And How To Keep Your Fingers

December 20, 2024 by Dan Maloney 1 Comment

Twas the week before Christmas when Elliot and Dan sat down to unwrap a pre-holiday bundle of hacks. We kicked things off in a seasonally appropriate way with a PCB Christmas card that harvests power from your microwave or WiFi router, plus has the potential to be a spy tool. We learned how to grow big, beautiful crystals quickly, just in case you need some baubles for the tree or a nice pair of earrings. Speaking of last-minute gifts, perhaps you could build a packable dipole antenna, a very durable PCB motor, or a ridiculously bright Fibonacci simple add-on for your latest conference badge. We also looked into taking a shortcut to homebrew semiconductors via scanning electron microscopes, solved the mystery of early CD caddies, and discussed the sad state of table saw safety and the lamentable loss of fingers, or fractions thereof.

Download the zero-calorie MP3.

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Embossing Leather With A Pipe Bender And 3D Printed Tooling

December 20, 2024 by Lewin Day 5 Comments

Embossed leather belts can be deliciously stylish. However, the tooling for making these fashionable items is not always easy to come by, and it rarely comes cheap. What do we do when a tool is expensive and obscure? We 3D print our own, as [Myth Impressions] demonstrates.

The build is based around a Harbor Freight pipe bender. However, instead of the usual metal tooling, it’s been refitted with a printed embossing ring specifically designed for imprinting leather. The tool features raised ridges in an attractive pattern, and the pipe bender merely serves as a straightforward device for rolling the plastic tooling over a leather belt blank. Once cranked through the machine, the leather belt comes out embossed with a beautiful design.

It’s a neat project, and the 3D printed tooling works surprisingly well. The key is that leather is relatively soft, so it’s possible to use plastic tools quite effectively. With that said, you can even form steel with printed tooling if you use the right techniques.

We’ve seen some other neat leatherworking hacks before, like this nicely-modified Singer sewing machine.

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Subchannel Stations: The Radio Broadcasts You Didn’t Know Were There

December 20, 2024 by Lewin Day 9 Comments

Analog radio broadcasts are pretty simple, right? Tune into a given frequency on the AM or FM bands, and what you hear is what you get. Or at least, that used to be the way, before smart engineers started figuring out all kinds of sneaky ways for extra signals to hop on to mainstream broadcasts.

Subcarrier radio once felt like the secret backchannel of the airwaves. Long before Wi-Fi, streaming, and digital multiplexing, these hidden signals beamed anything from elevator music and stock tickers to specialized content for medical professionals. Tuning into your favorite FM stations, you’d never notice them—unless you had the right hardware and a bit of know-how.

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Multimeter Gets Socket Upgrade To Use Nicer Probes

December 20, 2024 by Lewin Day 4 Comments

[Piffpaffpoltrie] had a problem. They found the InLine VA40R to be a perfectly usable multimeter, except for a couple of flaws. Most glaring among these were the tiny sockets for the test probes. These proved incompatible with the probes they preferred to use, so naturally, something had to be done.

The desire was to see the multimeter work with [Piffpaffpoltrie]’s connector of choice: the 4 mm Multi Contact banana plug from Stäubli. Swiss-made, gold-plated, and highly reliable, nothing else would do. The original sockets on the multimeter were simply too small to properly accept these, so to make them work, they were machined down, drilled, tapped, and then fitted with a short M3 screw which was then soldered in place. This short length of thread then allowed the new sockets to bolt right into the PCB in place of the original sockets.

Ultimately, many would just buy a new multimeter. This hack is a fiddly and time-consuming one, but it’s kind of neat to see someone go to such lengths to customize their tools to their own satisfaction.

We don’t see a lot of multimeter hacks, because these tools usually get all the necessary features from the manufacturer. Still, the handful we’ve featured have proven most interesting. If you’re tinkering away at customizing your own test gear, don’t hesitate to drop us a line!

Watch A 3D Scan Become A Car Body Model

December 20, 2024 by Donald Papp No comments

Not all 3D scanning is alike, and the right workflow can depend on the object involved. [Ding Dong Drift] demonstrates this in his 3D scan of a project car. His goal is to design custom attachments, and designing parts gets a lot easier with an accurate 3D model of the surface you want to stick them on. But it’s not as simple as just scanning the whole vehicle. His advice? Don’t try to use or edit the 3D scan directly as a model. Use it as a reference instead.

Rather than manipulate the 3D scan directly, a better approach is sometimes to use it as a modeling reference to fine-tune dimensions.

To do this, [Ding Dong Drift] scans the car’s back end and uses it as a reference for further CAD work. The 3D scan is essentially a big point cloud and the resulting model has a very high number of polygons. While it is dimensionally accurate, it’s also fragmented (the scanner only captures what it can see, after all) and not easy to work with in terms of part design.

In [Ding Dong Drift]’s case, he already has a 3D model of this particular car. He uses the 3D scan to fine-tune the model so that he can ensure it matches his actual car where it counts. That way, he’s confident that any parts he designs will fit perfectly.

3D scanning has a lot of value when parts have to fit other parts closely and there isn’t a flat surface or a right angle to be found. We saw how useful it was when photogrammetry was used to scan the interior of a van to help convert it to an off-grid camper. Things have gotten better since then, and handheld scanners that make dimensionally accurate scans are even more useful.

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