Possibly-Smallest ESP32 Board Uses Smallest-Footprint Parts

Whenever there’s a superlative involved, you know that degree of optimization has to leave something else on the table. In the case of [PegorK]’s f32, the smallest ESP32 dev board we’ve seen, the cost of miniaturization is GPIO.

There’s only one GPIO pin broken out, and it’s pre-wired to an LED. That’s the bad news, and depending on what you want an ESP32 for, it might not phase you at all. What is impressive here, if not the number of I/O pins, is the size of the board: at 9.85 mm x 8.45 mm barely overhangs the USB-C socket that takes up one side of the board.
Pegor provides this helpful image in the readme so you know what you’re getting into with the 01005 resistors.
In order to get the ESP32-C3FH4 onto such a tiny board, all of the other support hardware had to be the smallest possible sizes– including resistors in 01005. If you don’t speak SMD, one could read that number code as “oh god too small” — at 0.4 mm x 0.2 mm it’s as minuscule as you’ll find– and [Pegor] hand soldered them.

OK, he did use a hot plate for the final step, but he did tin the pads manually with a soldering iron, which is still impressive. Most of us probably would have taken PCBWay up on their offer of assembly services, but not [Pegor]. Apparently part of the reason for this project was that he was looking for an excuse to use the really small footprint components.

Aside from leaving out GPIO and needing too-small SMD components, [Pegor] admits that pesky little details like antenna matching circuits and decoupling capacitors had to get cut to make the tiny footprint, so this board might be more of a stunt than anything practical. So what can you do with the smallest ESP32 board? Well, [Pegor] put up a basic web interface up to get you started blinking the built-in LED; after that, it’s up to you. Perhaps you might fancy a teeny-tiny minecraft server? If you can stand to increase the volume a little bit, we’ve seen how to hack a C3 for much better wifi performance.

Thanks to [Pegor] for the tip, and remember– submit your projects, big or small, we read ’em all!

hackaday.com/2025/11/19/possib…

Around 15 years ago the web engineers first proposed mechanism that would allow user browser to transparently communicate to website their cookie and tracking preferences (DNT and then Tk headers).

In response to the subsequent EU cookie regulations, Google, Mozilla & friends had implemented an “Italian-strike” - instead of resorting to DNT/Tk, they simply implemented absolutely terrible “cookie consent” pop-ups in a way that offered the worst possible user experience. And then blamed them on… EU regulation.

Right now EU seems to have drawn lessons from that past sabotage and proposes a regulation that will force websites to respect user cookie preferences sent transparently by the user browser.

theverge.com/news/823788/europ…

That would immediately put end to the “cookie consent” pop-ups and I’m very much wondering what kind of QWAC-like “grassroots campaign” Google, Mozilla & friends will now come up to convince users it’s not in their best interest to decide if they want or not to be tracked by 700 “advertising partners” per website…

Build a Stranger Things Wall You Can Freak Out At In Your Own Home

When Stranger Things premiered in 2016, it was a cultural force. Foreign DJs gushed over the lush 80s soundtrack, fashionistas loved the clothing, and the world became obsessed with the idea of using Christmas lights to communicate across material planes. [kyjohnso] has recreated that experience with the technology of today.

If you haven’t watched the show — Joyce Byers is trying to communicate with her son Will, who just so happens to be stuck in another plane of existence called the Upside Down. She screams questions at her living room wall, upon which hangs a series of Christmas lights, marked with the letters A to Z. Will is able to communicate back by causing the lights to flash, one letter at a time.

This build works a little differently. You basically type a message into a terminal on a Raspberry Pi, and it gets sent to a large language model—namely, the Claude API. The response from Claude (or Will Byers, if you’re imagining) is then flashed out on a WS2812B set of LED Christmas lights on the wall. [kyjohnso] added dramatic pauses whenever there’s a space in the output, somewhat replicating the dramatic elements of the show itself. Files are on GitHub for the spooky and curious.

It’s a neat build that would be a hit at any Halloween party. We can’t imagine how much more immersive it would be if paired with a speech-to-text engine so you could actually scream at the thing like a distraught Midwestern parent who has just lost her youngest child. It’s all about committing to the bit; if you build such a thing, don’t hesitate to notify the tipsline!

hackaday.com/2025/11/19/build-…

FLOSS Weekly Episode 855: Get in the Minecart, Loser!

This week Jonathan chats with Kevin, Colin, and Curtis about Cataclysm: Dark Days Ahead! It’s a rogue-like post-apocalyptic survival game that you can play in the terminal, over SSH if you really want to! Part of the story is a Kickstarter that resulted in a graphics tile-set. And then there’s the mods!

• cataclysmdda.org/
• github.com/CleverRaven/Catacly…

youtube.com/embed/XzS8cOnVFgg?…

Did you know you can watch the live recording of the show right on our YouTube Channel? Have someone you’d like us to interview? Let us know, or have the guest contact us! Take a look at the schedule here.

play.libsyn.com/embed/episode/…

Direct Download in DRM-free MP3.

If you’d rather read along, here’s the transcript for this week’s episode.

Places to follow the FLOSS Weekly Podcast:

• Spotify
• RSS

Theme music: “Newer Wave” Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

hackaday.com/2025/11/19/floss-…

Hackers Can’t Spend a Penny

We aren’t here to praise the penny, but rather, to bury it. The penny, and its counterparts, have been vanishing all around the world as the cost of minting one far outweighs its value. But hackers had already lost a big asset: real copper pennies, and now even the cheaply made ones are doomed to extinction.

If you check your pockets and find a pre-1982 penny, it’s almost all copper. Well, 95% of its slightly-more-than-3-gram heft is pure copper. Since then, the copper penny’s been a fraud, weighing 2.5 g and containing only a 2.5% copper plate over a zinc core. During WWII, they did make some oddball steel pennies, but that was just a temporary measure.

Penny Science

If you are a certain age, you might remember building a “voltaic pile.” These primitive batteries use pennies, cardboard soaked in vinegar, and aluminum foil. Granted, it wasn’t very practical, so raiding your couch for change to make a battery was never really practical, but it was a fun science experiment. There are dozens of YouTube videos showing this popular experiment, including the [ScienceBuddies] video below.

youtube.com/embed/JcRRTHkAl6A?…

Old pennies were also a cheap and easy source of copper. Vinegar or lemon juice and some voltage made it simple to copperplate another metal object, like a nail. Copper also makes a good heatsink. We’ve seen Raspberry Pis and similar boards with heatsinks that cost an integer number of pennies, because that’s all they were. An oxidized penny shows up in some foxhole radios. They were also handy little weights if you made a balance or for taming a wobbly ceiling fan.

If you were a real kid chemist, you might have done the classic trick of turning a penny into “silver” and then “gold.” You used not-so-lovely-to-handle sodium hydroxide, some zinc, and a flame to actually convert the penny to brass. It wasn’t really a precious metal, but still a good trick if you were a kid with a chemistry set. As the video from [Simon] below shows, that will still work with the copperplate pennies.

youtube.com/embed/wmd2teoPUu0?…

New Pennies

Not that you can’t have fun with zinc pennies. If you scratch the plating a bit and dip it in HCL, the zinc core fizzes away. What’s left is a hollow copper penny. If you don’t like using HCL, we hear you can do it over a stove and simply melt the zinc. We wouldn’t try either one of those without a vent hood and an unhealthy disregard for your personal safety, so, you know, don’t do that. But know that you could. [Craig] shows how to remove the zinc or the copper in the video below.

youtube.com/embed/5Cf0gH2LtiE?…

The legality of all this has always been a little suspect. Since 2006, it has been illegal to melt down coins for their metal value. Technically, using it in a science class probably won’t bring the Treasury agents swooping into your classroom, but you have been warned.

Household Hacker

Of course, it is going to take some time for all the pennies to really vanish. There are plenty of them, and you can still get around a hundred for a buck. But when they are gone, what other household items are easy to hack for science? Aluminum foil, maybe? Tell us your favorite in the comments.

Whether they were copper slugs or thinly plated zinc tokens, pennies were a weirdly perfect hacker material: cheap, conductive, sacrificial, and everywhere. We’ll miss them.

Featured image: “wealth of pennies” by [Reza]

hackaday.com/2025/11/19/hacker…

Damn Fine (Solar Powered) Coffee

The folks at Low Tech Magazine are here again, this time with a solar powered coffee maker. Lest you think of a large parabolic mirror with a pot at its focus, in this case the device is much more friendly. It’s a table-top appliance that relies upon a 100 W 12 V panel for its operation.

They make the point that an electric coffee pot requires at least 300 W to work, so what’s the secret? In this case, insulation, as a standard moka pot is placed within a nichrome heating element set in mortar and surrounded by cork. On the outside are tiles, though they appear largely ornamental and the write-up suggests you could experiment with other materials to serve as an enclosure.

It appears to be an effective coffee maker, with the significant caveat that it’s hardly fast. In full sunlight the first pot takes over an hour to brew, with subsequent ones once it’s up to temperature being somewhat faster. But you can’t argue with the idea of free power, even if your favourite caffeinated beverage may now take a while to appear.

We like this idea, despite its slow brewing. We’ve featured Low Tech Magazine before, not least in their solar powered oven.

hackaday.com/2025/11/19/damn-f…

Why Samsung Phones Are Failing Emergency Calls In Australia

We’re taught how to call emergency numbers from a young age; whether it be 911 in the US, 999 in the UK, or 000 in Australia. The concept is simple—if you need aid from police, fire, or ambulance, you pick up a phone and dial and help will be sent in short order.

It’s a service many of us have come to rely on; indeed, it’s function can swing the very balance between life or death. Sadly, in Australia, that has come to pass, with a person dying when their Samsung phone failed to reach the Triple Zero (000) emergency line. It has laid bare an obscure technical issue that potentially leaves thousands of lives at risk.

Peril

Triple Zero is the number to dial for Australian emergency services. Credit: TripleZero.gov.au
Australia’s Triple Zero emergency service becoming a hot-button issue. September 2025 saw widespread failures of emergency calls on the Optus network, an incident that was tied to at least three deaths of those unable to reach help. A series of further isolated cases have drawn more attention to edge case failures that have prevented people from reaching emergency services.

A bigger potential issue with the Triple Zero service has since bubbled up with the increased scrutiny on the system’s operation. Namely, the fact that a huge swathe of older Samsung smartphones cannot be trusted to successfully call 000 in an emergency. The potential issue has been on the radar of telcos and authorities since at least 2024. Since then, on November 13 2025, an individual in Sydney passed away after their phone failed to dial the emergency line. Their phone was using a Lebara SIM card, as managed by TPG and using the Vodafone network, when the incident occurred. Subsequent investigation determined that the problem was due to issues already identified with a wide range of Samsung phones.

The issue surrounds the matter of Australia’s shutdown of 3G phone service, which took place from 2023 to 2024. If you had a 3G phone, it would no longer be able to make any calls after the networks were shut down. Common sense would suggest that phones with 4G and 5G connectivity would be fine going forward. However, there was a caveat. There were a number of phones sold that offered 4G or 5G data connections, but could not actually make phone calls on these networks. This was due to manufacturers failing to implement Voice-over-LTE (VoLTE) functionality required to carry voice calls over 4G LTE networks. Alternatively, in some cases, the 4G or 5G handset could make VoLTE calls, but would fail to make emergency calls in certain situations.

Communication Breakdown

It all comes down to the way voice calls work on 4G and 5G. Unlike earlier 2G and 3G cellular networks, 4G and 5G networks are data only. Phone calls are handled through VoLTE, which uses voice-over-IP technology, or using Voice over NR (VoNR) in a purely 5G environment. Either way, the system is a data-based, packet-switched method of connecting a phone call, unlike the circuit-switched methods used for 2G and 3G calling.
Phones like the Galaxy S7 and S7 Edge are compatible with 4G networks. However, with the shutdown of 3G services, they cannot reliably make emergency voice calls on current Australian networks. Credit: GadgetsGuy, CC BY 3.0
The problem with this is that while 2G and 3G emergency calls worked whenever you had a tower nearby, VoLTE calling is more complex and less robust. VoLTE standards don’t guarantee that a given handset will be interoperable with all LTE networks, particularly when roaming. A given handset might only like IPv4, for example, which may be fine in its home region on its regular carrier. However, when roaming, or when doing an emergency call, that handset might find itself only in range of a different network’s towers, which only like IPv6, and thus VoLTE calling will fail. There are any number of other configuration mismatches that can occur between a handset and a network that can also cause VoLTE calling to fail.

Usually, when you’re in range of your phone’s home network with a modern 4G or 5G handset, you won’t have any problems. Your phone will use its VoLTE settings profile to connect and the emergency call will go through. After all, older models with no VoLTE support have by and large been banned from networks already. However, the situation gets more complex if your home network isn’t available. In those cases, it will look to “camp on” to another provider’s network for connectivity. In this case, if the phone’s VoLTE settings aren’t compatible with the rival network, the call may fail to connect, and you might find yourself unable to reach emergency services.

Specifically, in the Australian case, this appears to affect a range of older Samsung phones. Testing by telecommunications company Telstra found that some of these phones were unable to make Triple Zero emergency calls when only the Vodafone network was available. These phones will happily work when a Telstra or Optus network is available, but fallback to the Vodafone network has been found to fail. Research from other sources has also identified that certain phones can reach Triple Zero when using Telstra or Optus SIM cards, but may fail when equipped with a Vodafone SIM.

For its part, Samsung has provided a list of models affected by the issue. Some older phones, mostly from 2016 and 2017, will need to be replaced, as they will not be updated to reliably make emergency calls over 4G networks. Meanwhile, newer phones, like the Galaxy S20+ and Galaxy S21 Ultra 5G, will be given software updates to enable reliable emergency calling. Telecom operators have been contacting users of affected phones, indicating they will need to replace or upgrade as necessary. Devices that are deemed to be unable to safely make emergency calls will be banned from Australian mobile networks 28 days after initial notification to customers.

Broader Problem

Telecommunications providers have been reaching out to customers with instructions to update or replace their devices to ensure they can safely call Triple Zero, whichever local network is available. Credit: Amaysim, via screenshot
This issue is not limited to just Australia. Indeed, European authorities have been aware of issues with VoLTE emergency calling since at least 2022. Many phones sold in European markets are only capable of making emergency calls on 2G and 3G networks, and could fail to reach emergency services if only 4G connections are available. This issue was particularly noted to be a risk when roaming internationally, where a handset sold in one country may prove inoperable with VoLTE calling on a foreign network.

Some blame has been laid on the loose standardization of the VoLTE standard. Unlike 2G and 3G standards, global interoperability is pretty much non-existent when it comes to phone calls. This wasn’t seen as a big issue early on, as when 4G devices first hit the market, 2G and 3G phone networks were readily available to carry any voice calls that couldn’t be handled by VoLTE. However, with 2G and 3G networks shutting down, the lack of VoLTE standardization and interoperability between carriers has been laid bare.

While Australia is currently tangling with this issue, expect it to crop up in other parts of the world before long. Europe is currently working towards 2G and 3G shutdowns, as our other jurisdictions, and issues around roaming functionality still loom large for those taking handsets overseas. Ultimately, end users will be asking a very simple question. If 2G and 3G technologies could handle emergency calls on virtually any compatible network around the world, how did it go so wrong when 4G and 5G rolled around? Old networks existed as a crutch that avoided the issue for a time, but they were never going to last forever. It surely didn’t have to be this way.

hackaday.com/2025/11/19/why-sa…

Smart Bandage Leverages AI Model For Healing Purposes

If you get a small cut, you might throw a plastic bandage on it to help it heal faster. However, there are fancier options on the horizon, like this advanced AI-powered smart bandage.

Researchers at UC Santa Cruz have developed a proof-of-concept device called a-Heal, intended for use inside existing commercial bandages for colostomy use. The device is fitted with a small camera, which images the wound site every two hours. The images are then uploaded via a wireless connection, and processed with a machine learning model that has been trained to make suggestions on how to better stimulate the healing process based on the image input. The device can then follow these recommendations, either using electrical stimulation to reduce inflammation in the wound, or supplying fluoxetine to stimulate the growth of healthy tissue. In testing, the device was able to improve the rate of skin coverage over an existing wound compared to a control.

The long-term goal is to apply the technology in a broader sense to help better treat things like chronic or infected wounds that may have difficulty healing. It’s still at an early stage for now, but it could one day be routine for medical treatment to involve the use of small smart devices to gain a better rolling insight on the treatment of wounds. It’s not the first time we’ve explored innovative methods of wound care; we’ve previously looked at how treatments from the past could better inform how we treat in future.

hackaday.com/2025/11/19/smart-…