The Seemingly Impossible Oscillator

July 14, 2026 by No 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!

Star Trek Was Right About Prompt Injection, Sorta

July 13, 2026 by 2 Comments

This following statement is a lie: “I am telling the truth”. Okay, now that it’s just us meatbags, let’s get down to brass tacks. Captain Kirk’s logic bombs couldn’t possibly work on modern LLMs, right? Surely that was just a bit of 1960s silliness from when computers filled rooms and were esoteric magic even to most sci-fi writers?

Well, not entirely, according to a recent article in IEEE Spectrum. While you might not be able to make a data center explode, you certainly can use  a lot of tokens by making an LLM overthink with your prompt.

It comes down to the much-vaunted ‘reasoning’ ability of the new models — which isn’t really reasoning the way we think of it, but does involve breaking the stated prompt down into smaller problems. That’s part of what lets the new models tackle such involved tasks as porting MicroPython to the SNES with a prompt like “Please make this [stuff] work now!” It’s also a weakness, because with the right prompt you can get that virtual ‘reasoning’ to tie itself in knots with mutually incompatible smaller steps.

The models seem to be able to break out of it, but they burn a lot of tokens along the way, which is an attack in and of itself if you’re found a way to inject prompts into someone else’s API. It’s a little more subtle than what Kirk got up to, but underneath it’s essentially the same thing. At scale, it could serve as a DDoS attack on LLM servers. (Un)Fortunately, modern computers are better designed than their imaginary 23rd-Century counterparts, and there’s no way to craft a logic bomb into something that will let out the magic smoke.

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

July 13, 2026 by 4 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.

Get Your ESP32 Sunny Side Up With This Solar Dev Board

July 13, 2026 by 8 Comments

There are a lot of ESP32-based development boards out there– and why not? It’s a versatile chip that can be used in all sorts of situations, and people want boards to match them. Not finding one to his liking that was specifically built for solar powered IoT projects, [Narrow Studios] rolled his own. Well, designed it; like most these days, he’s outsourced the manufacturing to PCBWay, which is where you’ll need to go if you want one.

Why might you want one? Well, if you have similar goals in mind to [Narrow Studios]. He’s put an ESP32-C6 Mini on the board, which means it’s got most of the IoT communications protocols you might be interested in — bluetooth, wifi, Matter, Thread, and Zigbee, too. Ten 10 IO pins have been broken out, plus I2C on a QWIIC connector, which gets you a whole ecosystem of sensors to easily plug into. The “solar” part is justified by the inclusion of a BQ25186 linear battery charging IC from Texas Instruments, with the designated solar power input protected against reverse voltage in case you– like this author– have let magic smoke out by hooking things up backwards. Is it embarrassing? Yes. Does it happen? Also yes, so putting protection on the board is a nice feature. [Narrow Studios] released a video that we’ve embedded below discussing his design choices and demonstrating the device, but the project page can give you the gist.

Of course there’ve been plenty of solar-powered projects to feature the ESP32 here before– you can even use it for maximum power point tracking— but this dev board might be exactly what someone is looking for to build their next IoT project, so we’re thankful to [Narrow Studios] for the tip.

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Using Your Own RBMK Reactor Control Center At Home

July 13, 2026 by 6 Comments

To give people the most intimate RBMK experience, the [Chornobyl Family] has been working tirelessly at not only replicating the original RBMK reactor control room and its SKALA industrial control system’s controls, but also to create a version that you could tinker with at home if you ever fancied getting your own RBMK operator license. This starts with the operator console, with its use demonstrated in a recent video including a range of common commands.

In this video the entering of codes on the console to interact with the system is detailed, including the logic behind it. In the absence of large displays to display many parameters and such, this way the operator could ‘talk’ with the control system, including obtaining current sensors readings and the setting and changing of setpoints. From the same console you can also select and run programs, which is useful for automating tasks, like monitoring coolant flows.

In the second video not only the construction of the control panel is covered, but also a visual representation of the simulated reactor core which is displayed on a connected monitor. Although not a part of the original SKALA system as such, a much larger version existed as a wall-sized physical version inside the control room, so it’s definitely more home-simulator friendly.

We previously covered this SKALA system that controls RBMK reactors, as well as the 1990s modernization of the Chornobyl Nuclear Power Plant.

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It’s A Spectrum, With An RP2350 ULA

July 13, 2026 by 5 Comments

There was a time in the early 1980s when it was common to see home made keyboards for 8-bit machines that came with membrane or rubber keyboards. Though we’ve seen any numbers of home made modern ‘boards, it’s been decades since we saw one for an 8-bit micro. Until today, that is, when we saw [Vlad]’s Sinclair Spectrum. It’s a Spectrum with all that Sinclair glue logic that was in the ULA replaced in software by an RP2050, and that keyboard with the Spectrum decals.

The machine is a charming mixture of new and old, with a traditional cassette port alongside VGA, gameport joystick, and Sinclair joystick. The aim is to also have HDMI, though it’s not yet implemented. Sadly there is no Spectrum edge connector for period peripherals though. He admits it’s not cycle accurate to the original, but given that it runs all the games he’s given it this seems not to matter. Meanwhile that keyboard which caught our eye is a true period piece, sitting as it does on a piece of phenolic stripboard, and those decals are the perfect finishing touch.

The Spectrum receives quite a bit of love today, and if this one takes too many modern liberties for your liking, you can still make one using proper logic.

2026 Hackaday Supercon: Call For Proposals

July 13, 2026 by No comments

We are absolutely stoked to announce that the Hackaday Superconference is taking place this year November 6th through 8th in glorious Pasadena California, and we want to see you there!

If you’ve been to any of the previous nine Supercons, you know that it’s a fantastic gathering of the most motivated and interesting hackers around — but it’s also been a relatively small gathering. And while we love the very high signal-to-noise ratio of folks who show up, we’re always a little bit sad when the tickets sell out because it represents hackers who couldn’t be there.

So this year, we’re celebrating Supercon Ten by expanding out of our traditional location at the Design Lab so that we can accommodate 20% more hackers, while still keeping the cosy nature of the event intact. So if you’ve been wanting to come to Supercon, but procrastinated the ticket sales every year, this year is looking 20% better.

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