Year: 2024

Open Source Multimeter Raises The Bar For DIY Tools

December 25, 2024 by 29 Comments

Whether you only dabble in electronics as a hobby or it’s your full-time job, there are few tools as indispensable as the multimeter. In fact, we’d be willing to bet nearly everyone reading this site owns at least one of them. But as common and mindbogglingly useful as they may be, they aren’t perfect. Even the high-end models will invariably have some annoyance that only reveals itself once you become intimately acquainted with it.

Most people would just live with those quirks, especially when dealing with a cheaper model. But not [John Duffy]. Deciding nothing but perfection would do, he took every favorite feature he’d ever run into while using other multimeters and combined them into his scratch-built HydraMeter. In the process, he managed to come up with a few new ideas that push this device into a league of its own.

Some of the features of the HydraMeter will look familiar. You might even have them on your own personal meter, such as the wireless removable display module. Other features you’ll wish your meter had, such as the removable cartridge on the front of the device that lets you rapidly swap out a burned fuse. On the other side of the spectrum, there are some esoteric features that might leave you scratching your head. The ability to tell exactly how the meter is configured at a glance thanks to its exclusive use of toggle switches has a certain hacker appeal, but it’s a tricky user interface for most folks.

While the overall design of the HydraMeter may be divisive, one thing we can all agree on is that getting the project to this state took incredible determination. Over the years we’ve only seen a handful of individuals attempt to develop their own multimeters, and even then, none of them approached this level of fit and finish. The fact that [John] has turned all that effort over to the community by releasing his design under the CERN license is truly admirable.

[John] brought the HydraMeter out to Pasadena back in November for Supercon, and it got quite a reaction. And if you don’t like the user interface, it’s not hard to imagine how you could change it. This project has unquestionably pushed the state of the art for open source multimeters forward, and we’re eager to see where it goes from here.

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Break Me Off A Piece Of That Open Source Serial Adapter

December 25, 2024 by 10 Comments

We know, you’ve already got a USB to serial adapter. Probably several of them, in fact. But that doesn’t mean you couldn’t use one more — especially when it’s as as cleverly designed as this one from [Anders Nielsen].

The first thing you notice about this adapter, and the big departure from the ones that are likely littering your parts bin, is that it terminates in a full-size male DSUB9 connector. With the ability to be directly plugged into a RS-232 port, this adapter will certainly catch the eye of retrocomputer enthusiasts. With a clever arrangement of jumpers, you can even reconfigure the RX and TX lines to be straight-through or cross over as needed.

But if you’re working with something that doesn’t have a literal serial port, no worries. All of the lines coming from the CH340G chip are broken out to a header so you can connect it up to whatever device you’re working with via jumpers.

In fact, if you’re really sure you’ll never need that RS232 feature, the PCB is even designed in such a way that you can simply snap it off. Admittedly it might seem a little odd to get a device like this if you didn’t want that capability. But once broken off, it’s not like the components go to waste. [Anders] has designed the board in such a way that if you flip it over and install a right-angle header, you can use the RS232 segment on a breadboard.

But the list of features doesn’t stop there. There’s also a 3.3 V regulator on board that you can use to power external circuits, as well as breakouts for the data lines in the USB-C connector. In keeping with the theme of the device, that part of the PCB can also be snapped off if you want to use it elsewhere.

Most folks probably’ won’t need all the capabilities offered by this particular serial adapter, and that’s fine. We’re still happy that it’s out in the wild and available for the community to use and adapt as an open source project.

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close up of a TI-84 Plus CE running custom software

Going Digital: Teaching A TI-84 Handwriting Recognition

December 24, 2024 by 4 Comments

You wouldn’t typically associate graphing calculators with artificial intelligence, but hacker [KermMartian] recently made it happen. The innovative project involved running a neural network directly on a TI-84 Plus CE to recognize handwritten digits. By using the MNIST dataset, a well-known collection of handwritten numbers, the calculator could identify digits in just 18 seconds. If you want to learn how, check out his full video on it here.

The project began with a proof of concept: running a convolutional neural network (CNN) on the calculator’s limited hardware, a TI-84 Plus CE with only 256 KB of memory and a 48 MHz processor. Despite these constraints, the neural network could train and make predictions. The key to success: optimizing the code, leveraging the calculator’s C programming tools, and offloading the heavy lifting to a computer for training. Once trained, the network could be transferred to the calculator for real-time inference. Not only did it run the digits from MNIST, but it also accepted input from a USB mouse, letting [KermMartian] draw digits directly on the screen.

While the calculator’s limited resources mean it can’t train the network in real-time, this project is a proof that, with enough ingenuity, even a small device can be used for something as complex as AI. It’s not just about power; it’s about resourcefulness. If you’re into unconventional projects, this is one for the books.

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Pi’s Evil Twin Goes For Infinity

December 24, 2024 by 36 Comments

Most people know about the numerical constant pi (or π, if you prefer). But did you know that pi has an evil twin represented by the symbol ϖ? As [John Carlos Baez] explains, it and its related functions are related to the lemniscate as pi relates to circles. What’s a lemniscate? That’s the proper name for the infinity sign (∞).

[John] shows how many of the same formulas for pi also work for the lemniscate constant (the name for ϖ). Some  (as John calls them) “mutant” trig functions use the pi-like constant.

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Holiday Jukebox Gets ESP32, Home Assistant Support

December 24, 2024 by 14 Comments

If we’ve learned anything over the years, it’s that the only thing hardware hackers love more than a device festooned with buttons is one that’s covered in LEDs — so it’s no surprise that this “Mr Christmas” jukebox caught the eye of [Roberts Retro]. But while the holiday gadget might have been mildly entertaining in its stock configuration, he quickly realized that what it really needed was an ESP32 retrofit. After all, what good are all those buttons and LEDs if you can’t bend them to your will?

For the first half of the video, [Robert] treats us to a detailed teardown of the device, which as you might imagine, is largely hollow inside. This gave him plenty of room to graft in new hardware, which is really the best gift any of us could hope to find under the tree. In addition to the ESP32 development board, the jukebox also received a number of WS2812B addressable RGB LEDs, and a DFPlayer module to handle music playback.

With all the buttons wired up to inputs on the ESP32, [Robert] can reconfigure the jukebox to do pretty much whatever he wants with just changes to the software. In the video, he demonstrates how the buttons can be used to trigger the playback of individual songs stored on the DFPlayer’s SD card, which essentially replicates it’s stock functionality. A few lines of changed code later, those same buttons can be used to control devices via Home Assistant.

To get into the holiday spirit, [Roberts Retro] shows off the completed jukebox controlling his ESP-enabled LEGO train set — another of his festive upgrades that we covered back in 2022.

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A Twenty-Segment Display, Artistically

December 24, 2024 by 21 Comments

We all know and love the humble seven-segment display, right? And if you want to make characters as well as numbers, you can do an okay job with sixteen segments off the shelf. But if you want something more art-deco, you’ll probably want to roll your own. Or at least, [Ben] did, and you can find his designs up on GitHub.

Taking inspiration from [Posy]’s epic investigation of segmented displays, [Ben] sat down with a sketchpad and created his own 20-segment font that displays numbers and letters with some strange, but frankly lovely, segment shapes. There is no center line, so letters like “T” and numbers like “1” are a little skewed, but we think it’s charming.

We’ve seen about a bazillion takes on the seven-segment idea over the years here. Most recently, we fell in love with this 21-segment beauty, but honestly the original eight(!) segment patent version is charming as well. Anyway, picking a favorite segmented display at Hackaday is like picking your favorite child, if you have a few hundred children. We love them all.

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Keeping Track Of Old Computer Manuals With The Manx Catalog

December 24, 2024 by 4 Comments

An unfortunate reality of pre-1990s computer systems is that any manuals and documentation that came with them likely only existed on paper. That’s not to say there aren’t scanned-in (PDF) copies of those documents floating around, but with few of these scans being indexable by search engines like Google and Duck Duck Go, they can be rather tricky to find. That’s where the Manx catalog website seeks to make life easier. According to its stats, it knows about 22,060 manuals (9,992 online) across 61 websites, with a focus on minicomputers and mainframes.

The code behind Manx is GPL 2.0 licensed and available on GitHub, which is where any issues can be filed too. While not a new project by any stretch of the imagination, it’s yet another useful tool to find a non-OCR-ed scan of the programming or user manual for an obscure system. As noted in a recent Hacker News thread, the ‘online’ part of the above listed statistics means that for manuals where no online copy is known, you get a placeholder message. Using the Bitsavers website along with Archive.org may still be the most pertinent way to hunt down that elusive manual, with the Manx website recommending 1000bit for microcomputer manuals.

Have you used the Manx catalog, or any of the other archiving websites? What have been your experiences with them? Let us know in the comments.