The Pluto software-defined radio is placed on a desk, connected by three RF cables to an RF bridge circuit board. The RF bridge has a prominent ballon taking up most of its area.

Turning The Pluto SDR Into A Network Analyzer

June 5, 2025 by 1 Comment

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. Continue reading “Turning The Pluto SDR Into A Network Analyzer” →

Illustrated scheme of Sam Ben Yaakovs concept

Leakage Control For Coupled Coils

June 5, 2025 by 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 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. Continue reading “Leakage Control For Coupled Coils” →

Supercon 2024: From Consultant To Prototyper On A Shoestring Budget

June 5, 2025 by 10 Comments

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.

Continue reading “Supercon 2024: From Consultant To Prototyper On A Shoestring Budget” →

A Steady Vacuum For The Fastest Cassette Tape Drive Ever

June 5, 2025 by 39 Comments

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.

Continue reading “A Steady Vacuum For The Fastest Cassette Tape Drive Ever” →

Screens Of Death: From Diagnostic Aids To A Sad Emoji

June 5, 2025 by 57 Comments

There comes a moment in the life of any operating system when an unforeseen event will tragically cut its uptime short. Whether it’s a sloppily written driver, a bug in the handling of an edge case or just dumb luck, suddenly there is nothing more that the OS’ kernel can do to salvage the situation. With its last few cycles it can still gather some diagnostic information, attempt to write this to a log or memory dump and then output a supportive message to the screen to let the user know that the kernel really did try its best.

This on-screen message is called many things, from a kernel panic message on Linux to a Blue Screen of Death (BSOD) on Windows since Windows 95, to a more contemplative message on AmigaOS and BeOS/Haiku. Over the decades these Screens of Death (SoD) have changed considerably, from the highly informative screens of Windows NT to the simplified BSOD of Windows 8 onwards with its prominent sad emoji that has drawn a modicum of ridicule.

Now it seems that the Windows BSOD is about to change again, and may not even be blue any more. So what’s got a user to think about these changes? What were we ever supposed to get out of these special screens?

Continue reading “Screens Of Death: From Diagnostic Aids To A Sad Emoji” →

The bill of materials and the assembled smartwatch.

Piko, Your ESP32 Powered Fitness Buddy

June 5, 2025 by 3 Comments

Over on Hackaday.io there’s a fun and playful write-up for a fun and playful project — the Piko, an ESP32 powered smartwatch.

Our hackers [Iloke Alusala], [Lulama Lingela], and [Rafael Cardoso] teamed up to design and manufacture this wrist-worn fitness wearable. Made from an ESP32 Beetle C6 and using an attached accelerometer with simple thresholds the Piko can detect if you’re idle, walking, jogging, or sprinting; and at the same time count your steps.

Design sketches

The team 3D printed the requisite parts in PLA using the printer in their university makerspace. In addition to the ESP32 and printed parts, the bill of materials includes a 240×240 IPS TFT LCD display, a LIS331HH triple-axis accelerometer, a 200 mAh battery, and of course, a watch strap.

Demonstrating splendid attention to detail, and inspired by the aesthetic of the Tamagotchi and pixel art, the Piko mimics your current activity with a delightful array of hand-drawn animations on its display. Should you want to bring a similar charm to your own projects, all the source is available under the MIT license.

If you’re interested in smartwatch technology be sure to check out our recent articles: Smartwatches Could Flatten The Curve Of The Next Pandemic and Custom Smartwatch Makes Diabetes Monitoring Easier For Kids.

Continue reading “Piko, Your ESP32 Powered Fitness Buddy” →

Running FreeDOS And 8086tiny On The Game Boy Advance Because You Can

June 5, 2025 by 20 Comments

How many people haven’t looked at their Game Boy Advance (GBA) handheld gaming device and wondered how much better it might be if it could run FreeDOS. Inside an 8086 emulator. If you’re like [ZZAZZ] and similarly suffer intrusive project-related thoughts, then this might be a moment of clear recognition, somewhat like sharing one’s story at a Programmers Anonymous meeting, but we digress.

In the video, the basic premise of making even the 8086tiny emulator work on the GBA seemed improbable on the outset – courtesy of the rather limited memory environment provided by the GBA – before even daring to look at things like disk access.

However, letting silly things like segmented memory and mismatched memory addresses deter us from pleasing said intrusive thoughts would be beyond the pale. Ergo we get a shining example of how days of rewriting code, stripping code, debugging code, fixing alignment issues in code and writing work-arounds for newly discovered issues in code can ultimately lead to the proud moment where FreeDOS boots on the GBA.

Granted it takes over an hour to do so, and has to be started from a butchered Pokémon Emerald save file, courtesy of a well-known exploit in that game, thankfully preserved in counterfeit cartridges.

Admittedly we’re not sure what practical applications there are for FreeDOS on the GBA, but that’s never stopped hackers from taking on impossible projects before, so there’s no sense letting it get in the way now.

Continue reading “Running FreeDOS And 8086tiny On The Game Boy Advance Because You Can” →