Day: November 20, 2024

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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[James] and his Lemontron portable 3D printer

If Life Gives You Lemons, Build This Lemontron

November 20, 2024 by 11 Comments

What if your 3D printer could fit in a box of filament but still rival the build plate size of heavyweights? Enter the Lemontron, a free and open source portable printer making waves in the maker community for its compact form factor and budget-friendly price. Watch [James]’ video on his build story here. Built around the Positron drive—a unique mechanism introduced by [Kralyn] in 2022—the Lemontron is the latest evolution of this innovative design. Although Kralyn mysteriously disappeared, their work inspired other projects like the Positron JourneyMaker and this Lemontron.

The Lemontron started as a unibody chassis mod for the JourneyMaker but grew into a complete redesign, cutting costs in half without sacrificing performance. By eliminating expensive CNC parts, it’s entirely made from off-the-shelf components, bringing the build cost to just $413. Compare that to $800 for the JourneyMaker and $699 for the Positron v3.2 kit.

Overhead photo of [James]' hands assembling the Lemontron Portable 3D printerRecent video updates show the Lemontron in action, printing impressively large and complex models. It tackled a marble run with 80-degree unsupported overhangs and a ‘comically large’ Benchy, proving its capability. Its compact design, paired with robust performance, is an exciting alternative for tinkerers seeking quality on a budget.

The Lemontron is in its final development stages, with frequent updates dropping on its YouTube channel. If you’re in the market for a more “traditional” mini-printer, check out this cool suitcase model from 2014.

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With Core ONE, Prusa’s Open Source Hardware Dream Quietly Dies

November 20, 2024 by 147 Comments

Yesterday, Prusa Research officially unveiled their next printer, the Core ONE. Going over the features and capabilities of this new machine, it’s clear that Prusa has kept a close eye on the rapidly changing desktop 3D printer market and designed a machine to better position themselves within a field of increasingly capable machines from other manufacturers.

While some saw the incremental upgrades of the i3 MK4 as being too conservative, the Core ONE ticks all the boxes of what today’s consumer is looking for — namely high-speed CoreXY movement with a fully enclosed chamber — while still offering the build quality, upgradability, and support that the company has built its reputation on. Put simply it’s one of the most exciting products they’ve introduced in a long time, and exactly the kind of machine that many Prusa fans have been waiting for.

Unfortunately, there’s one feature that’s ominously absent from the Core ONE announcement post. It’s easy to overlook, and indeed, most consumers probably won’t even know it’s missing. But for those of us who are concerned with such matters, it’s an unspoken confirmation that an era has finally come to an end.

With the Core ONE, Prusa Research is no longer in the business of making open source 3D printer hardware, but that doesn’t mean that the printer isn’t hackable. It’s complicated, so read on.

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