Nuke Your Own Uranium Glass Castings In The Microwave

April 26, 2023 by Dan Maloney 20 Comments

Fair warning: if you’re going to try to mold uranium glass in a microwave kiln, you might want to not later use the oven for preparing food. Just a thought.

Granted, uranium glass isn’t as dangerous as it might sound. Especially considering its creepy green glow, which almost seems to be somehow self-powered. The uranium glass used by [gigabecquerel] for this project is only about 1% U₃O₈, and isn’t really that radioactive. But radioactive or not, melting glass inside a microwave can be problematic, and appropriate precautions should be taken. This would include making the raw material for the project, called frit, which was accomplished by smacking a few bits of uranium glass with a hammer. We’d recommend a respirator and some good ventilation for this step.

The powdered uranium glass then goes into a graphite-coated plaster mold, which was made from a silicone mold, which in turn came from a 3D print. The charged mold then goes into a microwave kiln, which is essentially an insulating chamber that contains a silicon carbide crucible inside a standard microwave oven. Although it seems like [gigabecquerel] used a commercially available kiln, we recently saw a DIY metal-melting microwave forge that would probably do the trick.

The actual casting process is pretty simple — it’s really just ten minutes in the microwave on high until the frit gets hot enough to liquefy and flow into the mold. The results were pretty good; the glass medallion picked up the detail in the mold, but also the crack that developed in the plaster. [gigabecquerel] thinks that a mold milled from solid graphite would work better, but he doesn’t have the facilities for that. If anyone tries this out, we’d love to hear about it.

Retrotechtacular: Putting Pictures On The Wire In The 1930s

April 25, 2023 by Dan Maloney 52 Comments

Remember fax machines? They used to be all the rage, and to be honest it was pretty cool to be able to send images back and forth over telephone lines. By the early 2000s, pretty much everyone had some kind of fax capability, whether thanks to a dedicated fax machine, a fax modem, or an all-in-one printer. But then along came the smartphone that allowed you to snap a picture of a document and send it by email or text, and along with the decrease in landline subscriptions, facsimile has pretty much become a technological dead end.

But long before fax machines became commonplace, there was a period during which sending images by wire was a very big deal indeed. So much so that General Motors produced “Spot News,” a short film to demonstrate how newspapers leveraged telephone technology to send photographs from the field. The film is very much of the “March of Progress” genre, and seems to be something that would have been included along with the newsreels and Looney Tunes between the double feature films. It shows a fictional newsroom in The Big City, where a cub reporter gets a hot tip about an airplane stunt about to be attempted out in the sticks. The editor doesn’t want to miss out on a scoop, so he sends a photographer and a reporter to the remote location to cover the stunt, along with a technology-packed photographic field car. Continue reading “Retrotechtacular: Putting Pictures On The Wire In The 1930s” →

Low-Cost RF Power Sensor Gets All The Details Right

April 25, 2023 by Dan Maloney 25 Comments

Dirty little secret time: although amateur radio operators talk a good game about relishing the technical challenge of building their own radio equipment, what’s really behind all the DIY gear is the fact that the really good stuff is just too expensive to buy.

A case in point is this super-low-cost RF power sensor that [Tech Minds (M0DQW)] recently built. It’s based on a design by [DL5NEG] that uses a single Schottky diode and a handful of passive components. The design is simple, but as with all things RF, details count. Chief among these details is the physical layout of the PCB, which features a stripline of precise dimensions to keep the input impedance at the expected 50 ohms. Also important are the number and locations of the vias that stitch the ground planes together on the double-sided PCB.

While [Tech Minds]’ first pass at the sensor hewed closely to the original design and used a homebrew PCB, the sensor seemed like a great candidate for translating to a commercial PCB. This version proved to be just as effective as the original, with the voltage output lining up nicely with the original calibration curves generated by [DL5NEG]. The addition of a nice extruded aluminum case and an N-type RF input made for a very professional-looking tool, not to mention a useful one.

[Tech Minds] is lucky enough to live within view of QO-100, ham radio’s first geosynchronous satellite, so this sensor will be teamed up with an ADC and a Raspberry Pi to create a wattmeter with a graphical display for his 2.4-GHz satellite operations.

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Hackaday Links: April 23, 2023

April 23, 2023 by Dan Maloney 7 Comments

Mark it on your calendars, folks — this is the week that the term RUD has entered the public lexicon. Sure, most of our community already knows the acronym for “rapid unscheduled disassembly,” and realizes its tongue-in-cheek nature. But given that the term has been used by Elon Musk and others to describe the ignominious end of the recent Starship test flight, it seems like RUD will catch on in the popular press. But while everyone’s attention was focused on the spectacular results of manually activating Starship’s flight termination system to end its by-then uncontrolled flight at a mere 39 km, perhaps the more interesting results of the launch were being seen in and around the launch pad on Boca Chica. That’s where a couple of hundred tons of pulverized reinforced concrete rained down, turned to slag and dust by the 33 Raptor engines on the booster. A hapless Dodge Caravan seemed to catch the worst of the collateral damage, but the real wrath of those engines was focused on the Orbital Launch Mount, which now has a huge crater under it.

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Tiny Three-Tube Receiver Completes Spy Radio Suite

April 22, 2023 by Dan Maloney 6 Comments

In our surface-mount age, it’s easy to be jaded about miniaturization. We pretty much expect every circuit to be dimensionally optimized, something that’s easy to do when SMDs that rival grains of sand are available. But dial the calendar back half a century or so and miniaturization was a much more challenging proposition.

Challenging, perhaps, but by no means unachievable, as [Helge Fyske (LA6NCA)] demonstrates with this ultra-compact regenerative vacuum tube receiver. It’s a companion to his recent “spy transmitter,” a two-tube radio built in — or on, really — an Altoids tin. The transmitter was actually a pretty simple circuit, just a crystal-controlled oscillator and an RF amplifier really, but still managed about 1.5 Watts output on the 80-meter ham band.

The receiver circuit ended up being much more complicated, as receivers do, and therefore harder to cram into the allotted space. [Helge]’s used a three-tube regenerative design, with one tube each devoted to the RF amp, detector/mixer, and audio amplifier stages. As in the transmitter, the receiver tubes are mounted on the outside of the box, with the inside crammed full of components. [Helge] had to be quite careful about component positioning, to prevent interstage coupling and other undesirable side effects of building in such close quarters.

Was it worth it? Judging by the video below, absolutely! We’ve rarely heard performance like that from even a modern receiver with all the bells and whistles, let alone from a homebrew design under such constraints. It sounds fantastic, and hats off to [Helge] for completing his spy radio suite in style.

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Hackaday Podcast 215: Autonomous Race Car, Espresso Robot, And Vintage Computers

April 21, 2023 by Dan Maloney 5 Comments

It’s podcast time again, and this time around Elliot and Dan took a grand tour through the week’s best and brightest hacks. We checked out an old-school analog cell phone that went digital with style, dug into a washing machine’s API, and figured out how to melt metal in the microwave — the right way. Does coffee taste better when it’s made by a robot? Of course it does! Can you get a chatbot to spill its guts? You can, if you know how to sweet talk it. Let’s play Asteroids on an analog oscilloscope, spoof facial recognition with knitting, and feel the need for speed with an AI-controlled model race car. And was VCF East worth the wait? According to Tom Nardi, that’s a resounding “Yes!”

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download your own personal copy!

Continue reading “Hackaday Podcast 215: Autonomous Race Car, Espresso Robot, And Vintage Computers” →

That Drone Up In The Sky? It Might Be Built Out Of A Dead Bird

April 19, 2023 by Dan Maloney 40 Comments

In a lot of ways, it seems like we’re in the “plateau of productivity” part of the hype cycle when it comes to drones. UAVs have pretty much been reduced to practice and have become mostly an off-the-shelf purchase these days, with a dwindling number of experimenters pushing the envelope with custom builds, like building drones out of dead birds.

These ornithopomorphic UAVs come to us from the New Mexico Insitute of Mining and Technology, where [Mostafa Hassanalian] runs the Autonomous Flight and Aquatic Systems lab. While looking into biomimetics, [Dr. Hassanalian] hit upon the idea of using taxidermy birds as an airframe for drones. He and his team essentially reverse-engineered the birds to figure out how much payload they’d be able to handle, and added back the necessary components to make them fly again.

From the brief video in the tweet embedded below, it’s clear that they’ve come up with a huge variety of feathered drones. Some are clearly intended for testing the aerodynamics of taxidermy wings in makeshift wind tunnels, while others are designed to actually fly. Propulsion seems to run the gamut from bird-shaped RC airplanes with a propeller mounted in the beak to true ornithopters. Some of the drones clearly have a conventional fuselage with feathers added, which makes sense for testing various subsystems, like wings and tails.

It’s easy to mock something like this, and the jokes practically write themselves. But when you think about it, the argument for a flying bird-shaped robot is pretty easy to make from an animal behavior standpoint. If you want to study how birds up close while they’re flying, what better way than to send in a robot that looks similar to the other members of the flock? And besides, evolution figured out avian flight about 150 million years ago, so studying how birds do it is probably going to teach us something.

Continue reading “That Drone Up In The Sky? It Might Be Built Out Of A Dead Bird” →