Author: Jenny List

3525 Articles

The Orphaned Sources At The Hacker Camp: What Happened Next

July 28, 2026 by 20 Comments

At the 2024 Electromagnetic Field event in the UK, some awkward items turned up at the swap meet: radioactive sources. Fortunately there was [Tryst] at hand, who works in the nuclear industry, so they were safely collected. At this year’s EMF he was back, with a talk about what happened next.

It seems they were an industrial version of the smoke detectors we’ll all be familiar with, containing the same Americium alpha emitters, but in greater quantity. Their path from industry to hacker camp is purposefully shrouded in mystery to avoid future incidents happening because people are scared to come forward, but it seems that but for a bit of post-Brexit regulatory chaos they would normally have been taken back by their Danish manufacturer for disposal.

We’re treated to a fascinating deep dive into radioactive source regulation and just what these sources are. In short, they’re not too dangerous as they are, but what makes them a worry is that they can easily be dismantled and their contents released. Ingestion of alpha particle emitters is a particular worry, so they must be kept safe and accounted for. Which leaves [Tryst] with a set of radioactive sources that sit in a regulatory grey area and can’t easily be disposed of. He ends by asking for suggestions as to how they might be used, of which we favor a true random number generator.

Light-hearted interludes aside, this is a cautionary tale for all of us who delight in digging through technological junk, and we are lucky that our community includes people with the expertise to do something about items like these. The full talk is below the break.

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A Labour Of Love Brings A Kids Book To The Spectrum

July 27, 2026 by 37 Comments

Back in the early 1980s when 8-bit home computers became affordable educational toys for children, the traditional paper publishing industry did its best to keep up. For a few brief years, there were children’s books dedicated to the innards of a computer in meticulous detail, and courtesy of [Jason Jacques] we have a chance to look at one of the lesser-known ones.

The British publisher Ladybird made a series of four computer books, and while the first three had content for both the Sinclair Spectrum and the BBC Micro, the last in the series only featured the BBC. [Jason] took that book and re-imagined the missing Sinclair Spectrum version.

The surprise is how deep it dives into the architecture of an 8-bit computer, and it’s refreshing to see something that’s not unduly dumbed-down for kids. We’re guessing that this would have appealed to the 5% of kids who ran with their computers rather than just playing Jet Set Willy back then, and we’re sure a few grown-up 50-somethings may remember it or books like it.

If you think you may have seen Ladybird books here before, it may be because we reviewed another influential tech book of theirs for kids. Meanwhile you can take a look at the contemporary computer books from their arch-rival Usborne.

Flexible PCBs: Not Only For The Few

July 27, 2026 by 2 Comments

Flexible printed circuit boards are a fascinating technique for making electronics venture beyond the two-dimensional, but surprisingly they’re not something many of us have worked with. [Jessica Stanley] gave a talk at the recent Electromagnetic Field event in the UK, exploring the different ways to make your electronics bend.

She starts with an overview of flexible electronics, detailing the techniques used with conventional polyimide substrates and etched copper.  We’re particularly enamoured of a stretchable PCB made by coiling a flexible circuit round a piece of elastic. Since she’s looking for techniques accessible to everyone that don’t either cost a fortune or require dangerous chemicals we look at conductive paint and electrolysis, before arriving at using a vinyl cutter to create adhesive traces.

We’ve no doubt all noticed that flexible PCBs can be ordered from the usual fabrication houses at a price, but the value in this talk lies in reminding the viewer that this is not the only path. She demonstrates well that simple flexible PCBs can be within the reach of almost anyone, which is perhaps the encouragement needed for people to try this medium. The full talk is below the break.

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A Music Box With A Very Modern Heart

July 27, 2026 by 3 Comments

A ballerina music box is a charming ornament, but it remains one that is limited by its mechanism to a very short performance. [ShielaDixon] has one, and decided to make so much more with it.

The music box mechanism is a simple clockwork motor with a comb that’s picked by a drum to make the notes. Her box retains the mechanism to give the ballerina her performance, but replaces the comb with a microcontroller and audio channel. This is no mere MP3 player though, instead it’s a music box in itself. Each note of the comb was sampled, and the board plays them just as the music box would, under instruction from a text file containing the music. The repertoire can now go on for far longer, and contain many more compositions.

We like this hack, for its effectiveness, and for its recreation of the music box rather than simply playing a recording. Meanwhile if you recognise [ShieldDixon] from these pages, we’ve in the past featured another musical project of hers, a MIDI recorder.

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The BornHack 2026 Cyber Ægg Is A Badge With A Life Afterwards

July 17, 2026 by 3 Comments

A problem facing the designers of event badges is this: what happens to the badge after the event? It’s one that designers have tried to solve in many ways with varying levels of success, whether that be by making it a dev board, a games console, a mesh-networked communicator, or as in the case of Electromagnetic Field, a continuing badge for future events. Ar BornHack 2026 they have taken a novel approach, by making it a useful desktop appliance. The BornHack Cyber Ægg is a half-egg-shaped badge with a 3D-printed case, and aside from its on-camp applications it’s both a desktop clock/calendar, and a MeshCore node.

Produced with the assistance of the badge.team European badge makers, it’s an egg-shaped PCB with a Nordic nRF52840 at its heart, a Semtech LoRa module, and an e-paper display. On-site there’s a Tamagotchi-style virtual pet game, an event calender, and an RFID token game, but it’s the other two features that give it a life after the camp. The clock and Meshcore, coupled with its case being designed with a flat spot to sit on a desk, make this badge as much an appliance as it is a badge. This is where it will sit in the Hackaday office, and we’re pretty sure most BornHack attendees will use it thus too.

We like this approach to giving a badge a life after the event, and we look forward to seeing what influence it has on future badges. A badge should be a thing to enjoy, not a piece of e-waste.

The Seemingly Impossible Oscillator

July 14, 2026 by 24 Comments

Back in the days when an integrated circuit meant a simple but expensive device such as a 741 or a 555, most electronics enthusiasts made do with discrete transistor circuits. The common emitter amplifier and its variants are the most familiar, but the humble 3-legged device can do so much more. A particularly obtuse circuit is the subject of examination by [lcamtuf], the reverse avalanche oscillator. A 2N2222, a capacitor, an LED, and a resistor, the transistor is the wrong way round, and there’s nothing on its base. Yet the LED flashes, what on earth is up!

The answer lies in avalanche breakdown, the behavior of a reverse biased diode junction as the voltage across it increases. Eventually the electric field reaches the point at which an avalanche of electrons crosses the depletion layer, and the junction conducts. When connected across an RC circuit, the voltage in the capacitor slowly rises to the point at which avalanche breakdown occurs, and the capacitor abruptly discharges. As the voltage falls the avalanche conduction stops, and the cycle repeats itself. It’s a relaxation oscillator.

We’re treated to an explanation of why a transistor behaves this way and why a simple diode doesn’t, due to a “hump” in its I/V curve, and why the emitter-base junction has a lower breakdown voltage than the collector-base. It’s one of those circuits which looks as though it shouldn’t work, but never fails to oscillate.

Want to know more about transistors? Do we have the series for you!

Can’t Find That ISA Sound Card? No Worries!

July 13, 2026 by 19 Comments

Many older hackers will have at some point gotten rid of an old piece of hardware that they later ended up regretting. All those ISA cards were next to useless back in 2006, but now their relative rarity plus the popularity of retrocomputing makes them sought-after. But if it’s a sound card you’re after then never fear! [Schlae] has got you covered, with the Beavis Ultrasound. It may have a name reminiscent of a ’90s cartoon series, but it’s a clone of the Gravis Ultrasound from back in the day.

There is of course a snag, to build one you need an AMD AM78C201. Assuming you’ve found one in a surplus supplier though, the rest of the card is analogue, some glue logic, and a ROM for samples. There is also a GAL for driving the IDE CD-ROM interface, from the days when sound cards came with such things.

New ISA cards are cropping up here from time to time, such as this very handy storage and network card.