Illustrated scheme of Sam Ben Yaakovs concept

Leakage Control For Coupled Coils

June 5, 2025 by Heidi Ulrich 3 Comments

Think of a circuit model that lets you move magnetic leakage around like sliders on a synth, without changing the external behavior of your coupled inductors. [Sam Ben-Yaakov] walks you through just that in his video ‘Versatile Coupled Inductor Circuit Model and Examples of Its Use’.

The core idea is as follows. Coupled inductors can be modeled in dozens of ways, but this one adds a twist: a tunable parameter 𝑥 between k and ₁ (where k is the coupling coefficient). This fourth degree of freedom doesn’t change L_₁, L_₂ or mutual inductance M (they remain invariant) but it lets you shuffle leakage where you want it, giving practical flexibility in designing or simulating transformers, converters, or filters with asymmetric behavior.

If you need leakage on one side only, set 𝑥=k. Prefer symmetrical split? Set 𝑥=1. It’s like parametric EQ, but magnetic. And: the maths holds up. As [Sam Ben-Yaakov] derives and confirms that for any 𝑥 in the range, external characteristics remain identical.

It’s especially useful when testing edge cases, or explaining inductive quirks that don’t behave quite like ideal transformers should. A good model to stash in your toolbox.

As we’ve seen previously, [Sam Ben-Yaakov] is at home when it comes to concepts that need tinkering, trial and error, and a dash of visuals to convey. Continue reading “Leakage Control For Coupled Coils” →

Fraens’ New Loom And The Limits Of 3D Printing

January 12, 2025 by Elliot Williams 8 Comments

[Fraens] has been re-making industrial machines in fantastic 3D-printable versions for a few years now, and we’ve loved watching his creations get progressively more intricate. But with this nearly completely 3D-printable needle loom, he’s pushing right up against the edge of the possible.

The needle loom is a lot like the flying shuttle loom that started the Industrial Revolution, except for making belts or ribbons. It’s certainly among the most complex 3D-printed machines that we’ve ever seen, and [Fraens] himself says that it is pushing the limits of what’s doable in plastic — for more consistent webbing, he’d make some parts out of metal. But that’s quibbling; this thing is amazing.

There are mechanical details galore here. For instance, check out the cam-chain that raises, holds, and lowers arms to make the pattern. Equally important are the adjustable friction brakes on the rollers that hold the warp, that create a controlled constant tension on the strings. (Don’t ask us, we had to Wikipedia it!) We can see that design coming in handy in some of our own projects.

On the aesthetic front, the simple but consistent choice of three colors for gears, arms, and frame make the build look super tidy. And the accents of two-color printing on the end caps is just the cherry on the top.

This is no small project, with eight-beds-worth of printed parts, plus all the screws, bearings, washers, etc. The models are for pay, but if you’re going to actually make this, that’s just a tiny fraction of the investment, and we think it’s going to a good home.

We are still thinking of making [Fraens]’s vibratory rock tumbler design, but check out all of his work if you’re interested in nice 3D-printed mechanical designs.

Continue reading “Fraens’ New Loom And The Limits Of 3D Printing” →

Pulling Backward To Go Forward: The Brennan Torpedo Explained

December 17, 2024 by Donald Papp 17 Comments

The Brennan torpedo, invented in 1877 by Louis Brennan, was one of the first (if not the first) guided torpedoes of a practical design. Amazingly, it had no internal power source but it did have a very clever and counter-intuitive mode of operation: a cable was pulled backward to propel the torpedo forward.

If the idea of sending something forward by pulling a cable backward seems unusual, you’re not alone. How can something go forward faster than it’s being pulled backward? That’s what led [Steve Mould] to examine the whole concept in more detail in a video in a collaboration with [Derek Muller] of Veritasium, who highlights some ways in which the physics can be non-intuitive, just as with a craft that successfully sails downwind faster than the wind.

The short answer is gearing, producing more force on the propeller by pulling out lots of rope.

Continue reading “Pulling Backward To Go Forward: The Brennan Torpedo Explained” →

8-Bit Computers Crunch Advanced Scientific Computations

December 1, 2024 by Bryan Cockfield 37 Comments

Although largely relegated to retrocomputing enthusiasts and embedded systems or microcontrollers now, there was a time when there were no other computers available other than those with 8-bit processors. The late 70s and early 80s would have seen computers with processors like the Motorola 6800 or Intel 8080 as the top-of-the-line equipment and, while underpowered by modern standards, these machines can do quite a bit of useful work even today. Mathematician [Jean Michel Sellier] wanted to demonstrate this so he set up a Commodore 64 to study some concepts like simulating a quantum computer.

The computer programs he’s written to do this work are in BASIC, a common high-level language of the era designed for ease of use. To simulate the quantum computer he sets up a matrix-vector multiplication but simplifies it using conditional logic. Everything is shown using the LIST command so those with access to older hardware like this can follow along. From there this quantum computer even goes as far as demonstrating a quantum full adder.

There are a number of other videos on other topics available as well. For example, there’s an AmigaBasic program that simulates quantum wave packets and a QBasic program that helps visualize the statistical likelihood of finding an electron at various locations around a hydrogen nucleus. While not likely to displace any supercomputing platforms anytime soon, it’s a good look at how you don’t need a lot of computing power in all situations. And, if you need a refresher on some of these concepts, there’s an overview on how modern quantum computers work here.

Libre Space Foundation Aims To Improve Satellite Tech

October 22, 2024 by Bryan Cockfield 27 Comments

There’s no shortage of movies, TV shows, and books that show a dystopian future with corporations run amok in outer space with little or no effective oversight. Dune, The Expanse, and The Dispossessed spring to mind as predicting different aspects of this idea, but there are plenty of other warnings throughout sci-fi depicting this potential future. One possible way of preventing this outcome is by ensuring that space is as open-sourced as possible and one group, the Libre Space Foundation (LSF), is working towards this end. Their latest is a project with Ondsel to develop and model a satellite deploying mechanism using almost entirely open source software.

The LSF had already designed the PICOBUS satellite launcher system that flew to space in 2022 and deployed a number of CubeSats, but the group needed more information about how the system would perform. They turned to Ondsel to help develop a multi-body dynamics (MBD) solver, managing simulations with mass-spring-damper models. The satellite launcher includes a large constant-force spring that pushes the CubeSats out of the device once the door is opened, and the model can now simulate their paths in space without gravity. The team will launch their next set of satellites sometime next year on an RFA-ONE rocket.

The LSF maintains a huge database of their open source space projects, including this one, on their GitLab page. Although it might seem like small potatoes now, the adoption of open source software and hardware by space-fairing entities can help further the democratization of low Earth orbit.

Thanks to [johnad] for the tip!

Misleading GPS, Philosophy Of Maps, And You

September 10, 2024 by Bryan Cockfield 19 Comments

The oft-quoted saying “all models are wrong, but some are useful” is a tounge-in-cheek way of saying that at some level, tools we use to predict how the world behaves will differ from reality in some measurable way. This goes well beyond the statistics classroom it is most often quoted in, too, and is especially apparent to anyone who has used a GPS mapping device of any sort. While we might think that our technological age can save us from the approximations of maps and models, there are a number of limitations with this technology that appear in sometimes surprising ways. [Kyle] has an interesting writeup about how maps can be wrong yet still be incredibly useful especially in the modern GPS-enabled world. Continue reading “Misleading GPS, Philosophy Of Maps, And You” →

Building AI Models To Diagnose HVAC Issues

August 8, 2024 by Bryan Cockfield 10 Comments

HVAC – heating, ventilation, and air conditioning – can account for a huge amount of energy usage of a building, whether it’s residential or industrial. Often it’s the majority energy consumer, especially in places with extreme climates or for things like data centers where cooling is a large design consideration. When problems arise with these complex systems, they can go undiagnosed for a time and additionally be difficult to fix, leading to even more energy losses until repairs are complete. With the growing availability of platforms that can run capable artificial intelligences, [kutluhan_aktar] is working towards a system that can automatically diagnose potential issues and help humans get a handle on repairs faster.

The prototype system is designed for hydronic (water-based) systems and uses two separate artificial intelligences, one to analyze thermal imagery of the system and look for problems like leaks, hot spots, or blockages, and the other to listen for anomalous sounds especially relating to the behavior of cooling fans. For the first, a CNC-like machine was built to move a thermal camera around a custom-built model HVAC system and report its images back to a central system where they can be analyzed for anomalies. The second system which analyses audio runs its artificial intelligence on a XIAO ESP32C6 and listens to the cooling fans running in the model.

One problem that had to be tackled before any of this could be completed was actually building an open-source dataset to train the AI on. That’s part of the reason for the HVAC model in this project; being able to create problems to train the computer to detect before rolling it out to a larger system. The project’s code and training models can be found on its GitHub page. It seems to be a fairly robust solution to this problem, though, and we’ll be looking forward to future versions running on larger systems. Not everyone has a hydronic HVAC system, though. As heat pumps become more and more popular and capable, you’ll need systems to control those as well.