Reducing emissions from human activity requires a great deal of effort in many different sectors. When it comes to land transport, the idea is generally to eliminate vehicles powered by combustion engines and replace them with electric vehicles instead. At a glance, the job is simple enough. We know how to build EVs, and the technology is getting to the point where they’re capable of replacing traditional vehicles in many applications.
Of course, the reality is not so simple. To understand the problem of converting transportation to electric drive en masse, you have to take a look at the big numbers. Focus in on the metrics of copper, and you’ll find the story is a concerning one.
The so-called Demon Core was a cursed object, a 6.2 kilogram mass of plutonium intended to be installed in a nuclear weapon. Instead, slapdash experimental techniques saw it feature in several tragic nuclear accidents and cause multiple fatalities. Now, you can build yourself a lamp themed after this evil dense sphere.
A later recreation of the infamous “Slotin Accident” that occurred with the Demon Core. Credit: Public Domain, Los Alamos National Laboratory
Creator [skelly] has designed the lamp to replicate the Slotin incident, where the spherical Demon Core was placed inside two half-spheres of beryllium which acted as neutron reflectors to allow it to approach criticality. Thus, the core is printed as a small sphere which is thin enough to let light escape, mimicking the release of radiation that doomed Louis Slotin. The outer spheres are then printed in silvery PLA to replicate the beryllium half-spheres. It’s all assembled atop a stand mimicking those used in the Los Alamos National Laboratory in the 1940s.
To mimic the Core’s deadly blue glow, the build uses cheap LED modules sourced from Dollar Tree lights. With the addition of a current limiting resistor, they can easily be run off USB power in a safe manner.
The Demon Core has become a meme in recent times, perhaps as a new generation believes themselves smart enough not to tinker with 6.2 kilograms of plutonium and a screwdriver. That’s not to say there aren’t still dangerous nuclear experiments going on, even the DIY kind. Be careful out there!
LEGO trains are fun to play with, but as with any model train, you so seldom have enough track to fulfill your greatest desires. YouTuber [brick_on_the_tracks] has come up with some creative ideas of his own to make track compatible with Lego trains using other techniques.
TRAINED LEGO PROFESSIONALS! DO NOT ATTEMPT IN REAL LIFE!
The most straightforward is to use the LEGO fence piece, first released in 1967. They can be laid in two rows, four studs apart, and they’ll serve as perfectly functional train track. It’s a 100% legal building technique as per the official LEGO rules, too. Official track pieces can be linked up by placing them on a 1-stud-high booster. [brick_on_the_tracks] argues that it’s up to nine times cheaper than using official track, but it depends on how you’re building your layout, and you need to take into account the need for a base plate.
On the sillier side of things, it’s actually possible to use mini-figures as track, too. Again, it’s a 100% legal technique, though the trains don’t run as smoothly compared to the fence track. It’s very amusing, though, and could be a fun addition to a build you’re taking to a local LEGO convention.
If you’re really strapped for cash though, you can go as far as using cardboard. It’s not legal in the LEGO world, and it’s pretty basic, but you could literally make up a layout using nothing but a craft knife and pizza boxes. We’ve actually featured other LEGO train hacks before, like this neat automatic decoupler design.
[Estefannie] is a proud cat owner, but one of her cats has a bad habit of eating plastic. That means she needs to keep an eye on that cat’s bowel movements, but with two cats in the house, it’s difficult to know who did what. Thus, she whipped up an AI system to log her cats bathroom visits and give her peace of mind.
It’s not the most glamorous project — [Estefannie] notes she took over 50,000 pictures of her cats using the litterbox to train Microsoft Azure’s Custom Vision model. But after some work, it could readily identify which cat was using the litter box when fed images from a NoIR camera. The system then differentiates between number 1 and number 2 via the time the cat spends in the litter box. It’s not perfect, but it works.
The Raspberry Pi runs a Node.JS server to collate the results, paired with a website front-end for easy data display. That way, anyone on [Estefannie’s] WiFi network can see who did what from a browser. We’ve seen cat litter boxes put on the Internet of Things before, and we’ve even seen people hack litterbox DRM, too.
Flying drones have been a part of modern warfare for a good few decades now. Initially, most of these drones were built by traditional military contractors and were primarily used by the world’s best-funded militaries. However, in recent conflicts in Syria, Ukraine, and elsewhere have changed all that. Small commercial drones and compact militarized models have become key tools on the battlefield, for offense, defence, and reconnaissance.
The theremin is popular for its eerie sound output and its non-contact playing style. While they’re typically built using analog hardware, [Linus Åkesson] decided to make one using the venerable Commodore 64.
The instrument works by measuring the capacitance between its two antennas and the Earth. As these capacitances are changed by a human waving their hands around near the respective pitch and volume antennas, the theremin responds by changing the pitch and volume of its output.
In this case, the humble 555 is pressed into service. It runs as an oscillator, with its frequency varying depending on the user’s hand position. There’s one each for pitch and volume, naturally, using a clamp and spoon as antennas. The C64 then reads the frequency the 555s are oscillating at, and then converts these into pitch and volume data to be fed to the SID audio chip.
[Linus Åkesson] demonstrates the build ably by performing a slow rendition of Amazing Grace. The SID synthesizer chip in the C64 does a passable job emulating a theremin, used here with a modulated pulse wave sound. It’s an impressive build and one we fully expect to see at a big chiptune show sooner rather than later. We’re almost surprised nobody came out with a C64 Theremin cartridge back in the day.
Multispectral imaging can be a useful tool, revealing all manner of secrets hidden to the human eye. [elad orbach] built a rig to perform such imaging using the humble Raspberry Pi.
The project is built inside a dark box which keeps outside light from polluting the results. A camera is mounted at the top to image specimens installed below, which the Pi uses to take photos under various lighting conditions. The build relies on a wide variety of colored LEDs for clean, accurate light output for accurate imaging purposes. The LEDs are all installed on a large aluminium heatsink, and can be turned on and off via the Raspberry Pi to capture images with various different illumination settings. A sheath is placed around the camera to ensure only light reflected from the specimen reaches the camera, cutting out bleed from the LEDs themselves.
Multispectral imaging is particularly useful when imaging botanical material. Taking photos under different lights can reveal diseases, nutrient deficiencies, and other abnormalities affecting plants. We’ve even seen it used to investigate paintings, too. Video after the break.
