Detecting Surveillance Cameras With The ESP32

September 26, 2025 by Lewin Day 38 Comments

These days, surveillance cameras are all around us, and they’re smarter than ever. In particular, many of them are running advanced algorithms to recognize faces and scan license plates, compiling ever-greater databases on the movements and lives of individuals. Flock You is a project that aims to, at the very least, catalogue this part of the surveillance state, by detecting these cameras out in the wild.

The system is most specifically set up to detect surveillance cameras from Flock Safety, though it’s worth noting a wide range of companies produce plate-reading cameras and associated surveillance systems these days. The device uses an ESP32 microcontroller to detect these devices, relying on the in-built wireless hardware to do the job. The project can be built on a Oui-Spy device from Colonel Panic, or just by using a standard Xiao ESP32 S3 if so desired. By looking at Wi-Fi probe requests and beacon frames, as well as Bluetooth advertisements, it’s possible for the device to pick up telltale transmissions from a range of these cameras, with various pattern-matching techniques and MAC addresses used to filter results in this regard. When the device finds a camera, it sounds a buzzer notifying the user of this fact.

Meanwhile, if you’re interested in just how prevalent plate-reading cameras really are, you might also find deflock.me interesting. It’s a map of ALPR camera locations all over the world, and you can submit your own findings if so desired. The techniques used by in the Flock You project are based on learnings from the DeFlock project. Meanwhile, if you want to join the surveillance state on your own terms, you can always build your own license plate reader instead!

[Thanks to Eric for the tip!]

Meter Mods Make Radioactive Prospecting More Enjoyable

September 24, 2025 by Dan Maloney 1 Comment

While we often get a detailed backstory of the projects we cover here at Hackaday, sometimes the genesis of a build is a bit of a mystery. Take [maurycyz]’s radiation survey meter modifications, for instance; we’re not sure why such a thing is needed, but we’re pretty glad we stumbled across it.

To be fair, [maurycyz] does give us a hint of what’s going on here by choosing the classic Ludlum Model 3 to modify. Built like a battleship, these meters would be great for field prospecting except that the standard G-M tube isn’t sensitive to gamma rays, the only kind of radiation likely not to be attenuated by soil. A better choice is a scintillation tube, but those greatly increase the background readings, making it hard to tease a signal from the noise.

To get around this problem and make rockhounding a little more enjoyable, [maurycyz] added a little digital magic to the mostly analog Ludlum. An AVR128 microcontroller taps into the stream of events the meter measures via the scintillation tube, and a little code subtracts the background radiation from the current count rate, translating the difference into an audible tone. This keeps [maurycyz]’s eyes on the rocks rather than on the meter needle, and makes it easier to find weakly radioactive or deeply buried specimens.

If you’re not ready to make the leap to a commercial survey meter, or if you just want to roll your own, we’ve got plenty of examples to choose from, from minimalist to cyberpunkish.

Two pieces of metal are sitting next to each other on a brick, with one edge touching. The copper end of a torch is directing a flame against the metal, and the metal is glowing brightly around the point where the flame contacts it.

Welding With Natural Gas And Oxygen

September 21, 2025 by Aaron Beckendorf 15 Comments

By virtue of its triple bond, acetylene burns hotter than any other common hydrocarbon when mixed with oxygen, but it isn’t the only flame hot enough for welding. With the assistance of a homemade oxygen concentrator, [Hyperspace Pirate] was able to make a natural gas torch that melts steel, even if welding with the torch remains difficult.

[Hyperspace Pirate] built his oxygen concentrator around a pressure-swing adsorption system, which uses two tanks of a molecular sieve to selectively adsorb and purge nitrogen, leaving behind mostly oxygen. [Hyperspace Pirate] used reverse-osmosis membrane casings as the tanks, solenoid valves to control gas flow, and an Arduino with some MOSFETs to control the timing. For fuel, he used a convenient source of natural gas, already installed in his garage: the water heater’s gas supply. Since the house’s meter regulates the gas down to a fairly low pressure, and the oxygen concentrator doesn’t produce high pressures, the torch didn’t need any inline regulators.

Inline check valves, on the other hand, were very much necessary, a mixture of oxygen and natural gas propagating back along the lines being undesirable for obvious reasons, and flashback arrestors would have been a good addition. [Hyperspace Pirate] built the torch itself out of copper tubing and needle valves, with a 0.9 mm MIG welder tip as the nozzle. Adjusting the gas mixture was mostly a matter of trial and error. With an oxygen-rich flame, it could cut thin metal decently well, but it tended to melt thick pieces more than it cut. On the other hand, even with a neutral flame, the water vapor in the exhaust oxidized steel, which made welding quite difficult, but not impossible.

The oxygen supply by itself was an entertaining tool, turning smoldering pieces of charcoal or steel wool violently incandescent. With the assistance of some steel wool, [Hyperspace Pirate] set a steel tube on fire. With a bit more oxygen, it would probably make an effective thermic lance. If you still want to do your welding with acetylene, he’s also made that before.

Continue reading “Welding With Natural Gas And Oxygen” →

O Brother, What Art Thou?

September 9, 2025 by Tyler August 19 Comments

Dedicated word processors are not something we see much of anymore. They were in a weird space: computerized, but not really what you could call a computer, even in those days. More like a fancy typewriter, with a screen and floppy disks. Brother made some very nice ones, and [Chad Boughton] got his hands on one for a modernization project.

The word processor in question, a Brother WP-2200, was chosen primarily because of its beautiful widescreen, yellow-phosphor CRT display. Yes, you read that correctly — yellow phosphor, not amber. Widescreen CRTs are rare enough, but that’s just different. As built, the WP-2200 had a luggable form-factor, with a floppy drive, ̶m̶e̶c̶h̶a̶n̶i̶c̶a̶l̶ clacky keyboard, and dot-matrix printer in the back. Continue reading “O Brother, What Art Thou?” →

Front and back view of the 13.7" monitor kit

Modos Is Open Hardware, Easy On The Eyes

September 8, 2025 by Tyler August 26 Comments

Since e-ink first hit the market a couple decades back, there’s always murmurs of “that’d be great as a second monitor”— but very, very few monitors have ever been made. When the commecial world is delivering very few options, it leaves room for open source hardware projects, like the Modos Glider and Paper Monitor, projects now seeking funding on Crowd Supply.

As far as PC monitors go, the Modos isn’t going to win many awards on specs alone. The screen is only 13.3″ across, and its resolution maxes out at 1600 x 1200. The refresh rate would be totally unremarkable for a budget LCD, at 75 Hz. This Paper Monitor isn’t an LCD, budget or otherwise, and for e-ink, 75 Hz is a blazing fast refresh rate. Continue reading “Modos Is Open Hardware, Easy On The Eyes” →

Maurice Brings Immersive Audio Recording To The Masses

September 7, 2025 by Tyler August 20 Comments

Immersive audio is the new hotness in the recording world. Once upon a time, mono was good enough. Then someone realized humans have two ears, and everyone wanted stereo. For most of us, that’s where it stopped, but audio connoisseurs kept going into increasingly baroque surround-sound setups — ending in Immersive Audio, audio that is meant to fully reproduce the three-dimensional soundscape of the world around us. [DJJules] is one of those audio connoisseurs, and to share the joy of immersive audio recording with the rest of us, he’s developed Maurice, a compact, low-cost immersive microphone.

Maurice is technically speaking, a symmetrical ORTF3D microphone array. OTRF is not a descriptive acronym; it stands for Office de Radiodiffusion Télévision Française, the fine people who developed this type of microphone for stereo use. The typical stereo ORTF setup requires two cardioid microphones and angles them 110 degrees apart at a distance of 17 cm. Maurice arrays four such pairs, all oriented vertically and facing 90 degrees from one another for fully immersive, 8-channel sound. All of those microphones are thus arrayed to capture sound omnidirectionally, and give good separation between the channels for later reproduction. The mountings are all 3D printed, and [DJJules] kindly provides STLs.

This is the speaker setup you need to get full use of Maurice’s recordings. Now let’s see Paul Allen’s speakers.

Recording eight audio channels simultaneously is not trivial for the uninitiated, but fortunately, [DJJules] includes a how-to in his post. We particularly like his tip to use resistor color coding to identify the XLR cables for different microphone channels. Playback, too, requires special setup and processing. [DJJules] talks about listening on his 7.1.4 stereo setup, which you can find in a companion post. That’s a lot of speakers, as you might imagine.

There are high-end headphones that claim to reproduce an immersive sound field as well, but we can’t help but wonder if you’d miss the “true” experience without head tracking. Even with regular department-store headphones, the demo recordings linked via the Instructable sound great, but that probably just reflects the quality of the individual microphones.

Audio can be a make-or-break addition to VR experiences, so that would seem to be an ideal use case for this sort of technology. Maurice isn’t the only way to get there; we previously focused on [DJJules]’s ambisonic microphone, which is another way to reproduce a soundscape. What do you think, is this “immersive audio” the new frontier of Hi-Fi, or do we call it a stereo for a reason? Discuss in the comments!

Powering A Submarine With Rubber Bands

September 4, 2025 by Fenix Guthrie 16 Comments

A look underneath the water’s surface can be fun and informative! However, making a device to go under the surface poses challenges with communication and water proofing. That’s what this rubber band powered submarine by [PeterSripol] attempts to fix!

The greatest challenge of building such a submersible was the active depth control system. The submarine is slightly negatively buoyant so that once the band power runs out, it returns to the surface. Diving is controlled by pitch fins, which will pitch downward under the torque applied by the rubber bands. Once the rubber band power runs out, elastic returns the fins to their natural pitch up position encouraging surfacing of the submarine. However, this results in uncontrolled dives and risks loss of the submersible.

Continue reading “Powering A Submarine With Rubber Bands” →