Look! It’s A Knob! It’s A Jack! It’s Euroknob!

April 28, 2025 by Dan Maloney 20 Comments

Are your Eurorack modules too crowded? Sick of your patch cables making it hard to twiddle your knobs? Then you might be very interested in the new Euroknob, the knob that sports a hidden patch cable jack.

Honestly, when we first saw the Euroknob demo board, we thought [Mitxela] had gone a little off the rails. It looks like nothing more than a PCB-mount potentiometer or perhaps an encoder with a knob attached. Twist the knob and a row of LEDs on the board light up in sequence. Nice, but not exactly what we’re used to seeing from him. But then he popped the knob off the board, revealing that what we thought was the pot body is actually a 3.5-mm audio jack, and that the knob was attached to a mating plug that acts as an axle.

The kicker is that underneath the audio jack is an AS5600 magnetic encoder, and hidden in a slot milled in the tip of the audio jack is a tiny magnet. Pop the knob into the jack, give it a twist, and you’ve got manual control of your module. Take the knob out, plug in a patch cable, and you can let a control voltage from another module do the job. Genius!

To make it all work mechanically, [Mitxela] had to sandwich a spacer board on top of the main PCB. The spacer has a large cutout to make room for the sensor chip so the magnet can rotate without hitting anything. He also added a CH32V003 to run the encoder and drive the LEDs to provide feedback for the knob-jack. The video below has a brief demo.

This is just a proof of concept, to be sure, but it’s still pretty slick. Almost as slick as [Mitxela]’s recent fluid-motion simulation pendant, or his dual-wielding soldering irons.

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Shine On You Crazy Diamond Quantum Magnetic Sensor

April 15, 2025 by Dan Maloney 21 Comments

We’re probably all familiar with the Hall Effect, at least to the extent that it can be used to make solid-state sensors for magnetic fields. It’s a cool bit of applied physics, but there are other ways to sense magnetic fields, including leveraging the weird world of quantum physics with this diamond, laser, and microwave open-source sensor.

Having never heard of quantum sensors before, we took the plunge and read up on the topic using some of the material provided by [Mark C] and his colleagues at Quantum Village. The gist of it seems to be that certain lab-grown diamonds can be manufactured with impurities such as nitrogen, which disrupt the normally very orderly lattice of carbon atoms and create a “nitrogen vacancy,” small pockets within the diamond with extra electrons. Shining a green laser on N-V diamonds can stimulate those electrons to jump up to higher energy states, releasing red light when they return to the ground state. Turning this into a sensor involves sweeping the N-V diamond with microwave energy in the presence of a magnetic field, which modifies which spin states of the electrons and hence how much red light is emitted.

Building a practical version of this quantum sensor isn’t as difficult as it sounds. The trickiest part seems to be building the diamond assembly, which has the N-V diamond — about the size of a grain of sand and actually not that expensive — potted in clear epoxy along with a loop of copper wire for the microwave antenna, a photodiode, and a small fleck of red filter material. The electronics primarily consist of an ADF4531 phase-locked loop RF signal generator and a 40-dB RF amplifier to generate the microwave signals, a green laser diode module, and an ESP32 dev board.

All the design files and firmware have been open-sourced, and everything about the build seems quite approachable. The write-up emphasizes Quantum Village’s desire to make this quantum technology’s “Apple II moment,” which we heartily endorse. We’ve seen N-V sensors detailed before, but this project might make it easier to play with quantum physics at home.

Microscopic view of chiral magnetic material

Twisting Magnetism To Control Electron Flow

March 22, 2025 by Heidi Ulrich 11 Comments

If you ever wished electrons would just behave, this one’s for you. A team from Tohoku, Osaka, and Manchester Universities has cracked open an interesting phenomenon in the chiral helimagnet α-EuP₃: they’ve induced one-way electron flow without bringing diodes into play. Their findings are published in the Proceedings of the National Academy of Sciences.

The twist in this is quite literal. By coaxing europium atoms into a chiral magnetic spiral, the researchers found they could generate rectification: current that prefers one direction over another. Think of it as adding a one-way street in your circuit, but based on magnetic chirality rather than semiconductors. When the material flips to an achiral (ferromagnetic) state, the one-way effect vanishes. No asymmetry, no preferential flow. They’ve essentially toggled the electron highway signs with an external magnetic field. This elegant control over band asymmetry might lead to low-power, high-speed data storage based on magnetic chirality.

If you are curious how all this ties back to quantum theory, you can trace the roots of chiral electron flow back to the early days of quantum electrodynamics – when physicists first started untangling how particles and fields really interact.

There’s a whole world of weird physics waiting for us. In the field of chemistry, chirality has been covered by Hackaday, foreshadowing the lesser favorable ways of use. Read up on the article and share with us what you think.

Hacking Flux Paths: The Surprising Magnetic Bypass

February 21, 2025 by Heidi Ulrich 6 Comments

If you think shorting a transformer’s winding means big sparks and fried wires: think again. In this educational video, titled The Magnetic Bypass, [Sam Ben-Yaakov] flips this assumption. By cleverly tweaking a reluctance-based magnetic circuit, this hack channels flux in a way that breaks the usual rules. Using a simple free leg and a switched winding, the setup ensures that shorting the output doesn’t spike the current. For anyone who is obsessed with magnetic circuits or who just loves unexpected engineering quirks, this one is worth a closer look.

So, what’s going on under the hood? The trick lies in flux redistribution. In a typical transformer, shorting an auxiliary winding invites a surge of current. Here, most of the flux detours through a lower-reluctance path: the magnetic bypass. This reduces flux in the auxiliary leg, leaving voltage and current surprisingly low. [Sam]’s simulations in LTspice back it up: 10 V in yields a modest 6 mV out when shorted. It’s like telling flux where to go, but without complex electronics. It is a potential stepping stone for safer high-voltage applications, thanks to its inherent current-limiting nature.

The original video walks through the theory, circuit equivalences, and LTspice tests. Enjoy!

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Simple Hardware Store Hack Keeps Your PCBs Right Where You Want Them

January 16, 2025 by Dan Maloney 30 Comments

Sometimes it’s the simplest hacks that make the biggest impact.

Take these DIY magnetic PCB vises for example. Sure, you can go out and buy purpose-built tools, but [Dylan Radcliffe] just made a trip to the hardware store for some nuts and bolts. He chose 3/8″-16 bolts, which would probably be around M10 for the rest of the world. The head of each bolt is ground flat so a ceramic disc magnet can be attached to it with CA glue, while the head of the bolt gets a plastic washer glued to it. Another plastic washer gets glued to a nut, which when threaded onto the bolt provides the light clamping force needed to hold a PCB. Make four of those and stick them to a steel plate with the magnets, and you can stop chasing your boards around the bench with a soldering iron.

As much as we like this idea — and we do; we’re heading to Home Depot to buy the needed parts this very evening — we can think of a few useful modifications. With a long bolt and two nuts rather than one, you could make a set of vises that are easily adjustable along the Z-axis. This could prove useful to those of us working under a microscope. Also, rather than making the bolts the magnetic part we bet you could lay down a flexible magnetic sheet, the kind you can feed into a printer to roll your own fridge magnets. We suspect that would hold the bolts firmly enough for most work while still allowing easy repositioning. We’d also favor flange nuts over plain hex nuts, to give a larger clamping area. We’d still include the plastic washers, though, or possibly switch to rubber ones.

There’s more than one way to skin this cat, of course, especially if you’ve got a Harbor Freight nearby and a well-stocked Lego bin.

Putting The New CryoGrip Build Plate To The Test

October 25, 2024 by Dave Rowntree 15 Comments

BIQU has released a new line of low-temperature build plates that look to be the next step in 3D printing’s iteration—or so YouTuber Printing Perspective thinks after reviewing one. The Cryogrip Pro is designed for the Bambu X1, P1, and A1 series of printers but could easily be adapted for other magnetic-bed machines.

The bed adhesion strength when cold is immense!

The idea of the new material is to reduce the need for high bed temperatures, keeping enclosure temperatures low. As some enclosed printer owners may know, trying to print PLA and even PETG with the door closed can be troublesome due to how slowly these materials cool. Too high an ambient temperature can wreak havoc with this cooling process, even leading to nozzle-clogging.

The new build plate purports to enable low, even ambient bed temperatures, still with maximum adhesion. Two versions are available, with the ‘frostbite’ version intended for only PLA and PETG but having the best adhesion properties. A more general-purpose version, the ‘glacier’ sacrifices a little bed adhesion but gains the ability to handle a much wider range of materials.

An initial test with a decent-sized print showed that the bed adhesion was excellent, but after removing the print, it still looked warped. The theory was that it was due to how consistently the magnetic build plate was attached to the printer bed plate, which was now the limiting factor. Switching to a different printer seemed to ‘fix’ that issue, but that was really only needed to continue the build plate review.

They demonstrated a common issue with high-grip build plates: what happens when you try to remove the print. Obviously, magnetic build plates are designed to be removed and flexed to pop off the print, and this one is no different. The extreme adhesion, even at ambient temperature, does mean it’s even more essential to flex that plate, and thin prints will be troublesome. We guess that if these plates allow the door to be kept closed, then there are quite a few advantages, namely lower operating noise and improved filtration to keep those nasty nanoparticles in check. And low bed temperatures mean lower energy consumption, which is got to be a good thing. Don’t underestimate how much power that beefy bed heater needs!

Ever wondered what mini QR-code-like tags are on the high-end build plates? We’ve got the answer. And now that you’ve got a pile of different build plates, how do you store them and keep them clean? With this neat gadget!

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Overcomplicating The Magnetic Compass For A Reason

October 18, 2024 by Dan Maloney 17 Comments

Some inventions are so simple that it’s hard to improve them. The magnetic compass is a great example — a magnetized needle, a bit of cork, and a bowl of water are all you need to start navigating the globe. So why in the world would you want to over-complicate things with something like this Earth inductor compass? Just because it’s cool, of course.

Now, the thing with complication is that it’s often instructive. The simplicity of the magnetic compass masks the theory behind its operation to some degree and completely fails to deliver any quantitative data on the Earth’s magnetic field. [tsbrownie]’s gadget is built from a pair of electric motors, one intact and one stripped of its permanent magnet stators. The two are mounted on a 3D printed frame and coupled by a long shaft made of brass, to magnetically isolate them as much as possible. The motor is powered by a DC supply while a digital ammeter is attached to the terminals on the stator.

When the motor spins, the stator at the other end of the shaft cuts the Earth’s magnetic lines of force and generates a current, which is displayed on the ammeter. How much current is generated depends on how the assembly is oriented. In the video below, [tsbrownie] shows that the current nulls out when oriented along the east-west axis, and reaches a maximum along north-south. It’s not much current — about 35 microamps — but it’s enough to get a solid reading.

Is this a practical substitute for a magnetic compass? Perhaps not for most use cases, but a wind-powered version of this guided [Charles Lindbergh]’s Spirit of St. Louis across the Atlantic in 1927 with an error of only about 10 miles over the trip, so there’s that. Other aircraft compasses take different approaches to the problem of nulling out the magnetic field of the plane.

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