Neural Net Reads The Gas Meter

July 21, 2026 by 18 Comments

In an ideal world, the role of technology would be to make all of our lives easier. And although all the ads suddenly appearing in our smart TVs and gaming systems might make it seem otherwise, some technology can still improve our lives if we work hard at it. For [Cian], that meant training a neural network to read his gas meter so he wouldn’t have to do it himself.

The root issue here is twofold, first that [Cian]’s gas company hasn’t upgraded their own technology to modern, remote-readable meters, and second that the meter can’t be read by a gas employee because it’s hidden in the depths of [Cian]’s basement. This latter fact requires him to delve into Moria-like depths to get to the meter, so the solution here was to place a Raspberry Pi in this location instead. With a camera pointed at the meter, it’s not quite capable of discerning digits on its own so a neural network was trained in order to get accurate readings of the dial. And, finally, since the machine is networked already [Cian] set it up to automatically notify the gas company of its reading so he is now completely out of the loop.

For automating tedious tasks like these, the Raspberry Pi with something like OpenCV as a computer vision tool is a fairly mature platform for light machine learning duties like these. We’ve seen license plate readers as well as neighborhood traffic surveys built on these platforms to help automate human labor away, making our lives easier one single-board computer at a time.

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Postal IRCs Are Almost A Thing Of The Past

July 21, 2026 by 12 Comments

Have you ever found out that something you remember from your youth is now gone, and you didn’t even notice? If you are a certain age, you might feel that way when I deliver the news: You haven’t been able to buy International Reply Coupons (IRCs) at a US Post Office since early 2013. By the end of 2026, you won’t be able to buy them anywhere. The age of the IRC is over.

What’s an IRC?

An IRC from 1978 (public domain).

If that didn’t mean anything to you, you might be too young to remember, or maybe you just weren’t into shortwave listening or ham radio. Although there were other reasons to get IRCs, a radio hobby is the most likely reason a Hackday reader would have bought an IRC.

For radio purposes, here’s the problem. You’ve worked on your station for months, and one winter night, you finally pull in that rare station from Luxembourg. They’ll send you a QSL card to verify that you heard them. You only have to send them a letter telling them what time you heard them, what frequency, and some details about the program you heard. But they probably don’t want to pay the postage required to send hundreds or thousands of cards overseas.

While this is a radio-specific problem, you might find the same issue with pen pals or when trying to buy things from an overseas company.

SASE

If everyone were in the same country, the solution would be easy. Take a stamp, put it on an envelope that has your address on it, and stuff it in with the letter. Or, you could just drop a stamp or two in the letter you sent.

The problem is, US postage won’t help Radio Luxembourg. On the other hand, the effort required for you to buy postage that works in Luxembourg would have been a nightmare.

Enter the UPU

The Universal Postal Union is a UN agency that is effectively an association of post offices in 192 countries. Their charter is to facilitate mailing things worldwide.

The IRCs date back to 1906. The idea is you buy an IRC at your post office. You send it to Radio Luxembourg, or wherever. There, the mail person at the radio station could go to their post office and trade the coupon for enough local postage to send a surface letter worldwide.

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Tired Of Xargs?

July 21, 2026 by 27 Comments

What if you want to do something in Linux for a lot of files? [Numerator] was tired of using xarg and other ways to handle this job and created bashumerate.

Some examples in the post of the “other ways” include:

find . -name '*.log' | xargs rm
find . -name '*.sh' -exec wc -l {} \;

You can, also, use a for loop, and if you are a programmer at heart, you may well do this:

for f in *.txt; do
  wc -l "$f"
done

Bashumerate handles all of the common cases in one tool and uses the same syntax for multiple kids of enumerations.

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Art of 3D printer in the middle of printing a Hackaday Jolly Wrencher logo

Giving Resin 3D Printers Another Shot After Six Years

July 21, 2026 by 19 Comments

My initial experience with a 3D printer came in 2020, when I got access to a buddy’s Creality LD-002R SLA printer. This was one of those awkward transition phases for SLA printers, where inefficient RGB LCDs finally got replaced by monochrome LCD panels, thus massively reducing the required exposure time and increasing the LCD panel’s lifespan.

The closely related Creality LD-002H is a monochrome SLA printer, but as this wasn’t the one that this friend opted for we had to learn the ropes on this more old-school printer. In terms of specifications this meant a build volume of 119 mm x 65 mm x 160 mm to play with and a claimed 26.1 µm resolution. Despite some struggles along the way, this machine churned out impressively high levels of detail with whatever cheap resin we threw at it, and even the post-printing processing became easy once we added a flex plate to the build plate and tweaked the cleaning and curing steps.

Despite all these positives, we both drifted away from resin printing, mostly due to the still messy and smelly printing process. FDM printers seemed like a better deal, especially after said buddy got his mittens on a used IDEX FDM printer. I would eventually go through a rather loathsome Creality Ender V2 experience before ending up with my current-day Elegoo Neptune 4, and resin printing seemed to be a thing of the past for me. Until recently, that is.

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Java Ring Restored After Nearly 30 Years

July 21, 2026 by 18 Comments

Back in the late 90s when absolutely everybody knew that Java was going to become the one programming language to rule them all, the Java Ring was handed out to folks at Java developer conferences as an example of how it was going to revolutionize smart wearable devices. Recently [Daisuke Yamazaki] got his mittens on one of these collector’s items to see about reviving it.

We talked about these rings and associated iButton devices before, with their intended use being primarily to act as authentication keys. For the Java Ring, this use was mostly just used as a kind of gag, whereby visitors to these conferences could specify their coffee preferences at a terminal, having this programmed into the ring so that they could get their desired cup of literal java at various bean juice dispensers around the conference site.

Talking to one of these iButton devices requires a so-called Blue Dot adapter, which [Yamazaki-san] purchased along with the ring. Although the device happily responded on the 1-wire bus, figuring out how to interact with the original Java-based firmware and answering the question of how much of the original information of someone’s coffee preferences in ’98 were retained would require more sleuthing.

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20 FPS On E-Paper Display Without Help

July 21, 2026 by 29 Comments

If electronic paper displays have one downside, it’s generally refresh rate. Earlier versions of the tech might only have been able to do single-digit frames per second, while modern, mid-range devices can sometimes manage 10-20 FPS — and that’s not including the frames needed to blank the display. Getting up past that double-digit barrier typically requires higher-end displays, more powerful processors or FPGAs, and more money. On the other hand, [Tony] was recently able to get 20 FPS out of an ESP32-based device without using any extra processing power.

The key to improving e-paper performance is understanding how the display actually works. The “ink” consists of microscopic charged pigment particles that physically move in response to electric fields, making the display much slower than LCD or OLED panels. Rather than fully erasing and redrawing every frame, the software takes advantage of the particles’ existing state by generating optimized driving waveforms that only move the particles needed to produce the next image. On the software side, an MPEG-like encoding is used so only changes between frames are transmitted and converted into these waveforms, reducing unnecessary data transfers and allowing much higher frame rates.

Tony’s method is able to drive 960×540 panels, like those found in the Lilygo or M5PaperS3, to 20 FPS, and these platforms are based on nothing more than the capable but limited ESP32 chip. It’s an impressive push, and worth checking out the video in the linked project page. We assume you’d need a little more to drive something like the massive e-paper display found in this home automation setup, though.

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Two maps of London turned into hexagonal regions heat mapped from white to peach to purple. The left map is according to: density, ratings, surprise, cuisine diversity, and independent share. The map on the right of merged data assigns the dominant hub type in a region. Purple is assigned a value of "Elite", reddish orange is "Strong", peach is "Everyday", and white/grey is "Weak." The five locations deemed to be the highest scorers were Ealing-Acton, Kingston Upon Thames, Enfield, Bromley, and Havering.

Google Maps Killed The Restaurant Star

July 20, 2026 by 8 Comments

We all know that Google and other big players pick and choose what information people see, but we sometimes overlook it outside of the search and social media space. [Lauren Leek] decided to take a look at how Google Maps picks winners and losers in the restaurant scene in London.

Building a machine learning model to determine a new restaurant recommendation (as one does), [Leek] uncovered interesting, and perhaps concerning, elements of how Google Maps ranks restaurants. Broken down by relevance, proximity, and prominence, many new restaurants face the issue of not drawing traffic without reviews and vice-versa causing a vicious cycle. Relevance and proximity are fairly straightforward, but what goes into “prominence?”

[Leek] found that “it is not just what people think of a place – it is how often people interact with it, talk about it, and already recognise it.” This leads to chains and high foot traffic areas awash in reviews while more out-of-the-way places find it more difficult to draw traffic. Some of this is expected and would be happening even when word of mouth was the primary way to find out where to eat, but as with many things, the algorithm amplifies this, along with the undisclosed paid placement of restaurants in Maps results.

While still in its infancy, [Leek] built a public dashboard where people can sort restaurants in the city. The machine learning algorithm is designed to identify places that are hidden gems that punch above their Google Maps weight and may make you look like the trendy one (if you live in London).

Zooming out further, [Leek] found larger clusters that revealed restaurant “diversity, in other words, is not just about taste. It is about where families settled, which high streets remained affordable long enough for a second generation to open businesses, and which parts of the city experienced displacement before culinary ecosystems could mature.”

If you want to step outside the algorithm mayhem, how about a good old-fashioned Web Ring? We’ve also addressed what’s an AI versus an algorithm, and Cory Doctorow advised us on how to reverse course on the current wave of enshittification.