Measuring The Mighty Roar Of SpaceX’s Starship Rocket

November 21, 2024 by 46 Comments

SpaceX’s Starship is the most powerful launch system ever built, dwarfing even the mighty Saturn V both in terms of mass and total thrust. The scale of the vehicle is such that concerns have been raised about the impact each launch of the megarocket may have on the local environment. Which is why a team from Brigham Young University measured the sound produced during Starship’s fifth test flight and compared it to other launch vehicles.

Published in JASA Express Letters, the paper explains the team’s methodology for measuring the sound of a Starship launch at distances ranging from 10 to 35 kilometers (6 to 22 miles). Interestingly, measurements were also made of the Super Heavy booster as it returned to the launch pad and was ultimately caught — which included several sonic booms as well as the sound of the engines during the landing maneuver.

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Simple Hydrogen Generator Makes Bubbles And Looks Cool

November 21, 2024 by 17 Comments

Hydrogen! It’s a highly flammable gas that seems way too cool to be easy to come by. And yet, it’s actually trivial to make it out of water if you know how. [Maciej Nowak] has shown us how to do just that with his latest build.

The project in question is a simple hydrogen generator that relies on the electrolysis of water. Long story short, run a current through water and you can split H2O molecules up and make H2 and O2 molecules instead. From water, you get both hydrogen to burn and the oxygen to burn it in! Even better, when you do burn the hydrogen, it combines with the oxygen to make water again! It’s all too perfect.

This particular generator uses a series of acrylic tanks. Each is fitted with electrodes assembled from threaded rods to pass current through water. The tops of the tanks have barbed fittings which allow the gas produced to be plumbed off to another storage vessel for later use. The video shows us the construction of the generator, but we also get to see it in action—both in terms of generating gas from the water, and that gas later being used in some fun combustion experiments.

Pedants will point out this isn’t really just a hydrogen generator, because it’s generating oxygen too. Either way, it’s still cool. We’ve featured a few similar builds before as well.

(Pedantic editor’s note: Because this build doesn’t separate the H2 from the O2, what you get is a stoichiometric mix, or HHO, or “Oxyhydrogen“. By virtue of being in exactly the right ratio to combust, this stuff is significantly more explosive than pure H2. Be careful!)

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Simple Stack Of Ferrites Shows How Fluxgate Magnetometers Work

November 20, 2024 by 8 Comments

Have you ever wondered how a magnetometer works? We sure have, which was why we were happy to stumble upon this article on simple homebrew fluxgate magnetometers.

As [Maurycy] explains, clues to how a fluxgate magnetometer works can be found right in the name. We all know what happens when a current is applied to a coil of wire wrapped around an iron or ferrite core — it makes an electromagnet. Wrap another coil around the same core, and you’ve got a simple transformer.

Now, power the first coil, called the drive coil, with alternating current and measure the induced current on the second, or sense coil. Unexpected differences between the current in the drive coil and the sense coil are due to any external magnetic field. The difference indicates the strength of the field. Genius!

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A variety of LEGO and the damage they've done to cardboard.

Stepping On LEGO For Science

November 20, 2024 by 34 Comments

You might say that the worst LEGO to step on is any given piece that happens to get caught underfoot, but have you ever thought about what the worst one would really be? For us, those little caltrops come to mind most immediately, and we’d probably be satisfied with believing that was the answer. But not [Nate Scovill]. He had to quantitatively find out one way or another.

The damage done to cardboard by both broken brittle brown LEGO, and angled LEGO.And no, the research did not involve stepping on one of each of the thousands of LEGO pieces in existence. [Nate] started by building a test rig that approximated the force of his own 150 lb. frame stepping on each piece under scrutiny and seeing what it did to a cardboard substrate.

And how did [Nate] narrow down which pieces to try? He took to the proverbial streets and asked redditors and Discordians to help him come up with a list of subjects.

If you love LEGO to the point where you can’t bear to see it destroyed, then this video is not for you. But if you need to know the semi-scientific answer as badly as we did, then go for it. The best part is round two, when [Nate] makes a foot out of ballistics gel to rate the worst from the first test. So, what’s the worst LEGO to step on? The answer may surprise you.

And what’s more dangerous than plain LEGO? A LEGO Snake, we reckon.

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A Tube Stereo Amplifier, From Scratch

November 20, 2024 by 16 Comments

A conventional tube amplifier has a circuit whose fundamentals were well in place around a hundred years ago, so there are few surprises to be found in building one today. Nevertheless, building one is still a challenge, as [Mike Freda shows us with a stereo amplifier in the video below the break.

The tubes in question are the 12AU7 double triode and 6L6 tetrode, in this case brand new PSVANE parts from China. The design is a very conventional single-ended class A circuit, with both side of the double triode being used for extra gain driving the tetrode. The output uses a tapped transformer with the tap going to the other grid in the tertode, something we dimly remember as being an “ultra-linear” circuit.

There’s an element of workshop entertainment in the video, but aside from that we think it’s the process of characterising the amp and getting its voltages right which is the take-away here. It’s not something many of us do these days, so despite the apparent simplicity of the circuit it’s worth a look.

These modern tubes come from a variety of different sources, we’ve attempted to track them down in the past.

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An image of a black carabiner-esque frame surrounding a round, yellow bezeled digital watch. A black paracord lanyard is attached to the top right of the black frame and a yellow button is visible near the top left of the frame.

A Cyberpunk Pocketwatch

November 20, 2024 by 20 Comments

For a time, pocketwatches were all the rage, but they were eventually supplanted by the wristwatch. [abe] built this cyberpunk Lock’n’Watch to explore an alternate history for the once trendy device.

The build was inspired by the chunky looks of Casio sport watches and other plastic consumer electronics from the 1980s and 90s. The electronics portion of this project relies heavily on a 1.28″ Seeed Studio Round Display and a Raspberry Pi 2040 XIAO microcontroller board. The final product features a faux segmented display for information in almost the same color scheme as your favorite website.

[abe] spent a good deal of the time on this project iterating on the bezel and case to hold the electronics in this delightfully anachronistic enclosure. We appreciated the brief aside on the philosophical differences between Blender, TinkerCAD, and Fusion360. Once everything was assembled, he walks us through some of joys of debugging hardware issues with a screen flicker problem. We think the end result really fulfills the vision of a 1980s pocketwatch and that it might be just the thing to go with your cyberdeck.

We’ve seen accelerometers stuffed into old pocketwatch cases, a more useful smart pocketwatch, or you could learn how to repair and restore vintage watches.

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