One of the joys of writing up the entries for the 2025 Component Abuse Challenge has come in finding all the different alternative uses for the humble transistor. This building block of all modern electronics does a lot more than simply performing as a switch, for as [Aleksei Tertychnyi] tells us, it can also function as a temperature sensor.
How does this work? Simple enough, the base-emitter junction of a transistor can function as a diode, and like other diodes, it shows a roughly 0.2 volt per degree voltage shift with temperature (for a silicon transistor anyway). Taking a transistor and forward biasing the junction with a 33 K resistor, he can read the resulting voltage directly with an analogue to digital converter and derive a temperature reading.
The transistor features rarely as anything but a power device in the projects we bring you in 2025. Maybe you can find inspiration to experiment for yourself, and if you do, you still have a few days in which to make your own competition entry.
When you think of a US Nuclear accident, you probably think of Three Mile Island. However, there have been over 50 accidents of varying severity in the US, with few direct casualties. (No one died directly from the Three Mile Island incident, although there are some studies that show increased cancer rates in the area.)
Indeed, where there are fatalities, it hasn’t been really related to the reactor. Take the four people who died at the Surry Nuclear Power Plant accident: they were killed when a steam pipe burst and fatally scalded them. At Arkansas Nuclear One, a 525-ton generator was being moved, the crane failed to hold it, and one person died. That sort of thing could happen in any kind of industrial setting.
But one incident that you have probably never heard of took three lives as a direct result of the reactor. True, it was a misuse of the reactor, and it led to design changes to ensure it can’t happen again. And while the incident was nuclear-related, the radiation didn’t kill them, although it probably would have if they had survived their injuries. Continue reading “The Deadliest US Nuclear Accident Is Not What You Think”→
There are various CAD challenges out there that come with bragging rights. Some, like the Certified Solid Works Professional Exam (CWSP) might actually look good on a resume. [Deltahedra] is apparently not too interested in padding his resume, nor does he have much interest in SolidWorks, and so decided to conquer the CWSP with FreeCAD in the name of open source — and to show us all how he did it.
Because these CAD exams are meant to show your chops with the program, the resulting video makes an awesome FreeCAD tutorial. Spoiler alert: he’s able to model the part, though it takes him about 15 minutes. After modeling the part, the CWSP exam needs you to find the mass of the part, which [Deltahedra] does with the FCInfo macro — which, of course, he shows us how to install and use. The second and third questions are similar: change some variables (it is a parametric modeling software, after all) and find the new mass. In a second exercise, he needs to modify the model according to a new drawing. Modifying existing models can sometimes be more difficult than creating them, but [Deltahedra] and FreeCAD pass with flying colors once again.
If you’re at all curious about what FreeCAD can do, this video is a really impressive demonstration of FreeCAD’s part modeling workbench. We’ve had a few FreeCAD guides of our on on Hackaday, like this one on reverse engineering STLs and this one on best practices in the software, but if you’d asked us before the release of v1.0 we’d never have guessed you could use it for a SolidWorks exam in 2025. So while there are kudos due to [Deltahedra], the real accolades belong to the hardworking team behind FreeCAD that has brought it this far. Bravo!
When you hear it said that “Modern steel is disposable by design”, your ears perk up, as you just caught the unmistakable sound of faux romanticism along with ‘lost ancient technology‘ vibes. Although it happens sometimes that we did lose something important, as with for example the ancient Roman concrete that turns out to have self-healing properties as a result of so-called hot mixing, this is decidedly an exception.
We nearly lost that technology because of the technological and scientific bonfire that was the prelude to a thousand years of darkness over Europe: called the Dark Ages, Middle Ages as well as the medieval period. Thus when you come across a slideshow video with synthesized monotonal voice-over which makes the bold claim that somehow medieval iron was superior and today’s metallurgy both worse and designed to break, you really have to do a spit-take. The many corrections in the comment section further reinforces the feeling that it’s more slop than fact.
One of the claims made is that the bloomery furnace beats the blast furnace, due to beneficial additives to the iron. Considering that the video cites its sources, it’s at least worthy of a dive into the actual science here. Are modern iron and steel truly that inferior and disposable?
For most of us, the days of having to insert a disc to play our media are increasingly behind us. But if you’d like to provide your kids with the experience, you could use CardFlix.
For the electronics, [Udi] used the readily available ESP8266 D1 Mini module connected via I2C to a PN532 NFC reader. To trigger the different movies, there are over 50 cards, each with not only its unique NFC tag but also small posters that [Udi] printed showing the show and then laminated, ensuring they will survive plenty of use. The D1 Mini and NFC reader are housed in a 3D printed case, which ends up being almost smaller than the 5V DC adapter powering it, allowing it to be mounted above an outlet out of the way. The deck of movie cards is also housed in a pair of printed boxes: the larger one for the whole collection and a small one for the most often used shows. Should you want to print your own, all the design files are provided in the write-up.
The D1 Mini was programmed using ESPHome. This firmware allows it to easily connect back to Home Assistant, which does most of the heavy lifting for this project. When a card is scanned, Home Assistant can tell which TV the scanner was near, allowing this system to be used in more than one location. It also knows which card was scanned so it can play the right movie. Home Assistant also handles ensuring the TV in question is powered on, as well as figuring out what service should be called for that particular movie to be shown.
Be sure to check out some of the other projects we’ve featured that use ESPHome to automate tasks.
When you are capturing audio from a speaker, you are rarely capturing the actual direct output of such a system. There are reflections and artifacts caused by anything and everything in the environment that make it to whatever detector you might be using. With the modern computation age, you would think there would be a way to compensate for such artifacts, and this is what [d.fapinov] set out to do.
[d.fapinov] has put together a code base for simulating and reversing environmental audio artifacts made to rival systems, entirely orders of magnitude higher in cost. The system relies on similar principles used in radio wave antenna transmission to calculate the audio output map, called spherical harmonic expansion. Once this map is calculated and separated from outside influence, you can truly measure the output of an audio device.
The only problem is that the project needs to be tested in the real world. [d.fapinov] has gotten this far but is unable to continue with the project. A way to measure audio from precise locations around the output is required, as well as the appropriate control for such a device.
The iconic X-wing ship design from Star Wars is something many a hobbyist have tried to recreate, and not always with success. While [German engineer] succeeded in re-imagining an FPV quadcopter as an X-wing fighter, the process also highlighted why there have been more failures than successes when it comes to DIY X-wing aircraft.
For one thing, the X-wing shape is not particularly aerodynamic. It doesn’t make a very good airplane. Quadcopters on the other hand rely entirely on precise motor control to defy gravity in a controlled way. It occurred to [German engineer] that if one tilts their head just so, an X-wing fighter bears a passing resemblance to a rocket-style quadcopter layout, so he set out to CAD up a workable design.
When flying at speed, the aircraft goes nearly horizontal and the resemblance to an X-wing fighter is complete.
One idea that seemed ideal but ultimately didn’t work was using four EDF (electric ducted fan) motors mounted in the same locations as the four cylindrical engines on an X-wing. Motors large enough to fly simply wouldn’t fit without ruining the whole look. A workable alternative ended up being the four props and brushless motors mounted on the ends of the wings, like you see here.
The unit still needed a lot of fine tuning to get to a properly workable state, but it got there. It takes off and lands vertically, like a classical quadcopter, but when flying at speed it levels out almost completely and looks just like an X-wing as it screams by. It’s in sharp contrast to the slow, methodical movements of this Imperial Shuttle drone.
There are also a couple design elements in [German engineer]’s build we thought were notable. The spring-loaded battery door (all 3D-printed, including the spring) looks handy and keeps the lines of the aircraft clean. And since it’s intended to be flown as an FPV (first person view) aircraft, the tilting camera mount in the nose swings the camera 90 degrees during takeoff and landing to make things a little easier on the pilot.
3D models for the frame (along with a parts list) are up for anyone who wants to give it a shot. Check it out in the video, embedded below.
