Watch An Electro-Permanent Magnet In Action

April 1, 2026 by Donald Papp No comments

Electro-permanent magnets (EPMs) are pretty nifty concepts, and if you aren’t familiar with them, they are permanent magnets with the ability to be electrically switched on or off. Unlike an electromagnet — which maintains a magnetic field only while power is applied — an EPM can remain “on” even when power is removed. Want to see one work? There’s a video embedded below that shows one off, but if you’d like to know how they work, we have you covered.

Inside are two types of magnet, one of which is permanent and the other being a semi-hard magnet paired with an electromagnetic coil. A semi-hard magnet’s flux can be changed by exposing it to a strong enough magnetic field, and that’s the key to making it work.

When both magnets work together, the EPM is “on” and acts like a permanent magnet. To turn the EPM off, the polarity of the semi-hard magnet is flipped with a short and powerful electromagnetic pulse, after which the two magnets oppose one another and more or less cancel each other out. So rather than generating a magnetic field, an EPM more accurately reconfigures it.

As intriguing as EPMs are, we haven’t really seen one properly in action until it was brought to our attention that [Dave Jones] of EEVblog tried one out last year. He received a Zubax FluxGrip EPM, which is intended for drone and robotic applications and can hold up to 25 kg. Watch [Dave] fire it up in the video (link is cued up to the 7:30 mark), it’s pretty interesting to see one of these actually work.

EPMs are not prohibitively expensive but they are not exactly cheap, either. But if a switchable magnet sounds up your alley and you can’t afford an EPM, consider an alternative “switchable” magnet design that works by momentarily canceling out a permanent magnet with a paired electromagnet. Unlike an EPM, it’s not a permanent switch but it would be enough to drop a payload.

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Improving FDM Filament Drying With A Spot Of Vacuum

March 31, 2026 by Maya Posch 24 Comments

Keeping your filament safely away from moisture exposure is one of the most crucial aspects of getting a good 3D print, with equipment like a filament dryer a standard piece of equipment to help drive accumulated moisture out of filament prior to printing or storage. Generally such filament dryers use hot air to accomplish this task over the course of a few hours, but this is not very efficient for a number of reasons. Increasing the vaporization rate of water without significantly more power use should namely be quite straightforward.

The key here is the vapor pressure of a liquid, specifically the point at which it begins to transition between its liquid and gaseous phases, also known as the boiling point. This point is defined by both temperature and atmospheric pressure, with either factor being adjustable. In a pressure cooker this principle is for example used to increase the boiling temperature of water, while for our drying purposes we can instead reduce the pressure in order to lower the boiling point.

Although a lower pressure is naturally more effective, we can investigate the best balance between convenience and effectiveness.

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See The Computers That Powered The Voyager Space Program

March 30, 2026 by Julian Scheffers 11 Comments

Have you ever wanted to see the computers behind the first (and for now only) man-made objects to leave the heliosphere? [Gary Friedman] shows us, with an archived tour of JPL building 230 in the ’80s.

A NASA employee picks up a camcorder and decides to record a tour of the place “before they replace it all with mainframes”. They show us computers that would seem prehistoric compared to anything modern; early Univac and IBM machines whose power is outmatched today by even an ESP32, yet made the Voyager program possible all the way back in 1977. There are countless peripherals to see, from punch card writers to Univac debug panels where you can see the registers, and from impressive cabinets full of computing hardware to the zip-tied hacks “attaching” a small box they call the “NIU”, dangling off the inner wall of the cabinet. And don’t forget the tape drives that are as tall as a refrigerator!

We could go on ad nauseum, nerding out about the computing history, but why don’t you see it for yourself in the video after the break?

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Laser Ranging Makes GPS Satellites More Accurate

March 29, 2026 by Maya Posch 25 Comments

Although GNSS systems like GPS have made pin-pointing locations on Earth’s sphere-approximating surface significantly easier and more precise, it’s always possible to go a bit further. The latest innovation involves strapping laser retroreflector arrays (LRAs) to newly launched GPS satellites, enabling ground-based lasers to accurately determine the distance to these satellites.

Similar to the retroreflector array that was left on the Moon during the Apollo missions, these LRAs will be most helpful with scientific pursuits, such as geodesy. This is the science of studying Earth’s shape, gravity and rotation over time, which is information that is also incredibly useful for Earth-observing satellites.

Laser ranging is also essential for determining the geocentric orbit of a satellite, which enables precise calibration of altimeters and increasing the accuracy of long-term measurements. Now that the newly launched GPS III SV-09 satellite is operational this means more information for NASA’s geodesy project, and increased accuracy for GPS measurements as more of its still to be launched satellites are equipped with LRAs.

Self-healing CMOS Imager To Withstand Jupiter’s Radiation Belt

March 29, 2026 by Maya Posch 14 Comments

Ionizing radiation damage from electrons, protons and gamma rays will over time damage a CMOS circuit, through e.g. degrading the oxide layer and damaging the lattice structure. For a space-based camera that’s inside a probe orbiting a planet like Jupiter it’s thus a bit of a bummer if this will massively shorted useful observation time before the sensor has been fully degraded. A potential workaround here is by using thermal energy to anneal the damaged part of a CMOS imager.

The first step is to detect damaged pixels by performing a read-out while the sensor is not exposed to light. If a pixel still carries significant current it’s marked as damaged and a high current is passed through it to significantly raise its temperature. For the digital logic part of the circuit a similar approach is used, where the detection of logic errors is cause for a high voltage pulse that should also result in annealing of any damage.

During testing the chip was exposed to the same level of radiation to what it would experience during thirty days in orbit around Jupiter, which rendered the sensor basically unusable with a massive increase in leakage current. After four rounds of annealing the image was almost restored to full health, showing that it is a viable approach.

Naturally, this self-healing method is only intended as another line of defense against ionizing radiation, with radiation shielding and radiation-resistant semiconductor technologies serving as the primary defenses.

Y-circuit comparison for a water and real electrical circuit

Watch Electricity Slosh: Visualizing Impedance Matching

March 28, 2026 by Danie Conradie 10 Comments

It’s one thing to learn about transmission lines in theory, and quite another to watch a voltage pulse bounce off an open connector. [Alpha Phoenix] bridges the gap between knowledge and understanding in the excellent videos after the break. With a simple circuit, he uses an oscilloscope to visualize the propagation of electricity, showing us exactly how signals travel, reflect, and interfere.

The experiment relies on a twisted-pair Y-harness, where one leg is left open and the other is terminated by a resistor. By stitching together oscilloscope traces captured at regular intervals along the wire, [Alpha Phoenix] constructs a visualization of the voltage pulse propagating. To make this intuitive, [Alpha Phoenix] built a water model of the same circuit with acrylic channels, and the visual result is almost identical to the electrical traces.

For those who dabble in the dark art of RF and radio, the real payoff is the demonstration of impedance matching in the second video. He swaps resistors on the terminated leg to show how energy “sloshes” back when the resistance is too high or too low. However, when the resistor matches the line’s characteristic impedance, the reflection vanishes entirely—the energy is perfectly dissipated. It really makes it click how a well-matched, low SWR antenna is crucial for performance and protecting your radio.

[Alpha Phoenix] is a genius at making physics visible. He even managed “film” a laser beam traveling at light speed.
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Demonstrating Gray Codes With Industrial Display

March 25, 2026 by Bryan Cockfield 4 Comments

Many people base huge swaths of their lives on foundational philosophical texts, yet few have read them in their entirety. The one that springs to the forefront of many of our minds is The Art of Computer Programming by Donald Knuth. Full of many clever and outright revolutionary algorithms and new ways of thinking about how computers work, [Attoparsec] has been attempting to read this tome from cover to cover, and has found some interesting tidbits. One of those is the various algorithms around Gray Codes, and he built this device as a visual aid.

Gray Codes, otherwise known as reflected binary, is a way of ordering an arbitrarily large set of binary values so that only one bit changes between any two of them. The most common place these are utilized is in things like rotary encoders, where it provides better assurance that the position of a shaft is in a known location. To demonstrate this in a more visual way [Attoparsec] hooked up an industrial signal light, normally used for communicating the status of machinery in a factory, and then programmed it to display the various codes. A standard binary counter is used as a reference, and it can also display standard Gray Code as well as a number of other algorithms used for solving similar problems.

[Attoparsec] built this as an interactive display for the Open Sauce festival in San Francisco. To that end it needed to be fairly rugged, so he built it out of old industrial equipment, which is also a fitting theme for the light itself. There’s also a speed controller and an emergency stop button which also add to the motif. For a deeper dive on Gray Codes and their uses, take a look at this feature from a few years back.

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