BornHack is a week-long summer hacker camp in a forest on the Danish island of Fyn, that consistently delivers a very pleasant experience for those prepared to make the journey. This year’s version was the tenth iteration of the camp and it finished a week ago, and having returned exhausted and dried my camping gear after a Biblical rainstorm on the last day, it’s time to take a look at the badges. In case you are surprised by the plural, indeed, this event had not one badge but two. Last year’s badge suffered some logistical issues and arrived too late for the camp, so as a special treat it was there alongside the 2025 badge for holders of BornHack 2024 tickets. So without further ado, it’s time to open the pack for Hackaday and see what fun awaits us. Continue reading “Two For The Price Of One: BornHack 2024 And 2025 Badges”→
We’ve been loving the variety of entries to the 2025 One-Hertz Challenge. Many a clock has been entered, to be sure, but also some projects that step well outside simple timekeeping. Case in point, this AM transmitter from [oldradiofixer.]
The software-only transmitter uses an ATTiny85 processor to output an AM radio signal in the broadcast band. It transmits a simple melody that you can tune in on any old radio you might have lying around the house. Achieving this was simple. [oldradiofixer] set up the cheap microcontroller to toggle pin PB0 at 1 MHz to create an RF carrier. Further code then turns the 1MHz carrier on and off at varying rates to play the four notes—G#, A, G#, and E—of the Twilight Zone theme. This is set up to repeat every second—hence, it’s a perfectly valid entry to the 2025 One-Hertz Challenge!
It’s a simple project, but one that demonstrates the basics of AM radio transmission quite well. The microcontroller may not put out a powerful transmission, but it’s funny to think just how easy it is to generate a broadcast AM signal with a bit of software and a length of wire hanging off one pin. Video after the break.
Most of you know how an NFC tag works. The reader creates an RF field that has enough energy to power the electronics in the tag; when the tag wakes up, two-way communication ensues. We’re accustomed to blank tags that can be reprogrammed, and devices like the Flipper Zero that can emulate a tag. In between those two is [MCUer]’s power-free tag emulator, a board which uses NFC receiver hardware to power a small microcontroller that can run emulation code.
The microcontroller in question is the low-power CW32L010 from Wuhan Xinyuan Semiconductor, a Chinese part with an ARM Cortex M0+ on board. Unfortunately, that’s where the interesting news ends, because all we can glean from the GitHub repository is a PCB layout. Not even a circuit diagram, which we hope is an unintended omission rather than deliberate. It does, however, lend itself to the fostering of ideas, because if this designer can’t furnish a schematic, then perhaps you can. It’s not difficult to make an NFC receiver, so perhaps you can hook one up to a microcontroller and be the one who shares the circuit.
For as mysterious, fascinating, and beautiful as lightning is at a distance, it’s not exactly a peaceful phenomenon up close. Not many things are built to withstand millions of volts and tens to hundreds of thousands of amps. Unsurprisingly, there’s a huge amount of effort put into lightning protection systems for equipment and resources that need to be outside where thunderstorms sometimes happen. Although most of us won’t be building personal substations, church steeples, or city-scale water towers in our backyards, we might have a few radio antennas up in the air, so it’s a good idea to have some lightning protection and possibly an alert system like [Joe] built.
You would think detecting lightning would be easy. Each lightning bolt has a staggering amount of power, and, clearly, you can hear the results on any radio. But it is possible to optimize a simple receiver circuit to specifically pick up lightning. That’s exactly what [Wenzeltech] shows in a page with several types of lightning detectors complete with photos and schematics.
Just as with a regular radio, there are multiple ways to get the desired result. The first circuits use transistors. Later versions move on to op amps and even have “storm intensity” meters. The final project uses an ion chamber from a smoke detector. It has the benefit of being very simple, but you know, also slightly radioactive.
You might think you could detect lightning by simply looking out the window. While that’s true, you can, in theory, detect events from far away and also record them easily using any data acquisition system on a PC, scope, or even logic analyzer.
Why? We are sure there’s a good reason, but we’ve never needed one before. These designs look practical and fun to build, and that’s good enough for us.
This is a clever Spartan build. In order to create a radio beacon for use in a “fox hunt” [Jim] combined a SR-T300 walkie talkie module with a phototransistor and oscillating LED circuit. The phototransistor and oscillating LED are secured face-to-face inside heat shrink tubing which isolates them from ambient light. When the LED flashes on the phototransistor powers the radio which transmits a tone in the UHF band.
A fox hunt is a game played by radio enthusiasts in which players use radio signals to triangulate and find a hidden beacon. [Jim]’s circuit is the beacon, and when it’s powered by a three volt CR2032 battery, it transmits a strong signal over several hundred yards at 433.5 MHz, within the amateur radio UHF band.
If you’re interested in radio beacons you might like to read about the WSPR beacon.
EFI from cables is something every ham loves to hate. What if you modulated, that, though, using an ordinary cable as an antenna? If you used something ubiquitous like a video cable, you might have a very interesting exploit– which is exactly what [Xieyang Sun] and their colleagues have done withTEMPEST-LoRa, a technique to encode LoRa packets into video files.
The concept is pretty simple: a specially-constructed video file contains information to be broadcast via LoRa– the graphics card and the video cable serve as the Tx, and the Rx is any LoRa module. Either VGA or HDMI cables can be used, though the images to create the LoRa signal are obviously going to differ in each case. The only restriction is that the display resolution must be 1080×1920@60Hz, and the video has to play fullscreen. Fullscreen video might make this technique easy to spot if used in an exploit, but on the other hand, the display does not have to be turned on at the time of transmission. If employed by blackhats, one imagines syncing this to power management so the video plays whenever the screen blanks.
This image sends LoRa. Credit: TEMPEST-LoRa
According to the pre-print, a maximum transmission distance of 81.7m was achieved, and at 21.6 kbps. That’s not blazing fast, sure, but transmission out of a totally air-gapped machine even at dialup speeds is impressive. Code is on the GitHub under an MIT license, though [Xieyang Sun] and the team are white hats, so they point out that it’s provided for academic use.There is a demo video, but as it is on bilbili we don’t have an easy way to embed it. The work has been accepted to the ACM Conference on Computer and Communications Security (2025), so if you’re at the event in Taiwan be sure to check it out.
Thanks to [Xieyang Sun] for the tip! We’ll be checking the tips line for word from you, just as soon as we finish wrapping ferrites around all our cables.
