2025-06-06 10:00:01
[Daniel Salião Ferreira] may or may not be a Game of Thrones fan, but he does have a fun demo of the Seebeck effect in the form of a flashlight powered by fire and ice. The basic idea is to use a thermocouple, but — in this case — he uses a Peltier effect cooler.
The Peltier and Seebeck effects are two sides of the same coin: the Peltier effect creates heating and cooling when current flows through a thermoelectric material. In contrast, the Seebeck effect generates a voltage when there is a temperature gradient. While thermocouples do produce voltage this way, they usually have much lower power output and are useless as heat pumps.
Thermoelectric heat pumps — Peltier devices — use semiconductors, which allow them to reach higher temperature differences when used as a heat pump, and also perform better than a conventional metal thermocouple in reverse operation.
Generating power from waste heat is nothing new. Is it harder to do this with thermocouples? Yes. Yes, it is.
2025-06-06 07:00:26
These days, when you think reverb, you probably think about a guitar pedal or a plugin in your audio software. But you can also create reverb with a big metal plate and the right supporting electronics. [Tully] from [The Tul Studio] shows us how.
Basically, if you’ve ever smacked a big sheet of metal and heard the thunderous, rippling sound it makes, you already understand the concept here. To turn it into a studio effect, you use transducers to deliver the sound into the plate of metal, and then microphones to pick it back up again at some other point on the plate. Since the sound takes time to travel through the plate, you get a reverb effect.
[The Tul Studio] used a huge cold-rolled steel plate, standing one meter wide and two meters tall. The plate itself is hung from picture chain, which is strong enough to carry its weight. Old car tweeters are repurposed to act as pickups, while a larger speaker is used to drive sound into the plate. “The key to making it sound not like a tin can is the actual EQ and the electronics,” [Tully] explains, providing resources for this purposes.
We love lots of lovely reverbing things around these parts; oddball delays, too! Video after the break.
2025-06-06 04:00:05
Usually when we see a project using a software-defined radio (SDR), the SDR’s inputs and outputs are connected to antennae, but [FromConceptToCircuit]’s project connected an ADALM-Pluto SDR to an RF bridge and a few passive components to make a surprisingly effective network analyzer (part two of the video).
The network analyzer measures two properties of the circuit to which it is connected: return loss (S11) and insertion gain or loss (S21). To measure S21, the SDR feeds a series of tones to the device under test, and reads the device’s output from one of the SDR’s inputs. By comparing the amplitude of the input to the device’s output, a Python program can calculate S21 over the range of tested frequencies. To find S11, [FromConceptToCircuit] put an RF bridge in line with the device being tested and connected the bridge’s output to the SDR’s second input. This allowed the program to calculate the device’s impedance, and from that S11.
The RF bridge and other components introduce some inaccuracies to the measurements, so before making any other measurements, the system is calibrated with both a through connection and an open circuit in place of the tested device. The RF bridge’s directivity was the biggest limiting factor; transfer back from the bridge’s output line caused the reflection under load to exceed the reflection of an open circuit in some frequency ranges, at which point the analyzer couldn’t accurately operate.
[FromConceptToCircuit] was eventually able to make measurements throughout most of the 0.1-3 GHz range with a dynamic range of at least 10 dB, and expects a more directive RF bridge to give even better results. If you’d like to repeat the experiment, he’s made his Python program available on GitHub.
We’ve previously seen [FromConceptToCircuit] use the Pluto SDR to make a spectrum analyzer. We’ve also featured a guide to the Pluto, covered a project that improved its frequency stability, and seen it used to transmit video.
2025-06-06 02:30:47
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 L₁, L₂ 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.
2025-06-06 01:02:00
Many engineers graduate from their studies and head out into the workforce, seeking a paycheck and a project at some existing company or other. Often, it’s not long before an experienced engineer begins to contemplate striking out on their own, working as a skilled gun-for-hire that makes their own money and their own hours.
It’s a daunting leap, but with the promise of rich rewards for those that stick the landing. That very leap is one that our own Dave Rowntree made. He came to Supercon 2024 to tell us what the journey was like, and how he wound up working on some very special shoes.
Dave’s talk begins right at the start of his career. He graduated from college around the turn of the millenium, and headed right into to the big game. He landed a job at Phillips Semiconductors, and dived into what was then a rapidly-developing field—digital television! He quickly learned a great deal about embedded programming, but found the actual electronics skills he’d picked up during his studies weren’t being put to much use. Sadly, redundancies struck his company, and he was forced to pivot to stick around. A spot opened up in the IC test and manufacturing support group, and he jumped in there, before later decamping to a fabless semiconductor company as a test engineer. He then used his education and experience to leverage a leap into the design side of things, which brought the benefit of allowing him to join the royalty program.
Things were on the up for Dave, right until the redundancy train came around once again. The inconvenience, combined with a lack of jobs in his field in the UK, pushed him to consider a major lifestyle change. He’d strike out on his own.
At this time, he explains how he tangled with the many challenges involved in working for one’s self. Not least of which, the difficulty of actually establishing a functional business in the UK, from bureaucratic red tape to handling the necessary marketing and financials.
He found his first jobs by working with so-called “innovation companies”—which provide services to those looking for design help to bring their ideas to life. These companies generally lacked engineering staff, so Dave’s services proved valuable to this specific market. It provided Dave some income, but came with a problem. After several years, he realized he had no public portfolio of work, because everything he’d worked on was under a non-disclosure agreement of some form or other.
Eventually, he realized he’d ended up in a “box.” He’d become “the PCB guy,” finding his work stagnating despite having such a broad and underexploited skillset. This didn’t sit right, and it was time for change once again. “I’m just thinking I don’t want to be a PCB guy,” Dave explains. “I want to do it all.” Thus was born his push into new fields. He built an arcade machine, art installations, and kept working to push himself out of his comfort zone.
Eventually, something exciting came down the line that really inspired him. “Some guys wanted me to build something, and it was totally oddball,” he says. “They wanted me to put an airbag in a basketball shoe.” The concept was simple enough—the airbag was intended to deploy to protect the wearer if excessive ankle roll was detected. Building the shoe in real life would be the perfect opportunity for him to stretch his abilities.
Despite his initial misgivings around the idea of putting explosives in shoes, the team behind the idea were able to twist Dave’s arm. “If I want to break out of the box of being just a PCB guy, maybe this is it,” he thought. “Why the hell not!”
The rest of Dave’s talk covers how the project came to break him out of his design funk, and how he’s tackling the difficult engineering problems involved. Even more joyously, he’s able to talk openly about it since there’s no NDA involved. He compares plans to use pyrotechnic devices versus stored gas systems, tears down commercial shoes for research, and even his journey into the world of scanning feet and making his own force sensors. As much as he was leveraging his existing skill base, he’s also been expanding it rapidly to meet the new challenges of a truly wild shoe project.
Dave’s talk is an inspiring walk through how he developed a compelling and satisfying engineering career without just going by the book. It’s also an enjoyable insight into the world of weird airbag shoes that sound too fantastical to exist. If you’ve ever thought about leaving the career world behind and going out on your own, Dave’s story is a great one to study.
2025-06-05 23:30:00
If you think of a 1960s mainframe computer, it’s likely that your mental image includes alongside the cabinets with the blinkenlights, a row of reel-to-reel tape drives. These refrigerator-sized units had a superficial resemblance to an audio tape deck, but with the tape hanging down in a loop either side of the head assembly. This loop was held by a vacuum to allow faster random access speeds at the head, and this fascinates [Thorbjörn Jemander]. He’s trying to create a cassette tape drive that can load 64 kilobytes in ten seconds, so he’s starting by replicating the vacuum columns of old.
The video below is the first of a series on this project, and aside from explaining the tape drive’s operation, it’s really an in-depth exploration of centrifugal fan design. He discovers that it’s speed rather than special impeller design that matters, and in particular a closed impeller delivers the required vacuum. We like his home-made manometer in particular.
What he comes up with is a 3D printed contraption with a big 12 volt motor on the back, and a slot for a cassette on the front. It achieves the right pressure, and pulls the tape neatly down into a pair of loops. We’d be curious to know whether a faster motor such as you might find in a drone would deliver more for less drama, but we can see the genesis of a fascinating project here. Definitely a series to watch.
Meanwhile, if your interest extends to those early machine rooms, have a wallow in the past.
