Diagnosing Whisker Failure Mode In AF114 And Similar Transistors

July 6, 2025 by Maya Posch 13 Comments

The inside of this AF117 transistor can was a thriving whisker ecosystem. (Credit: Anthony Francis-Jones)

AF114 germanium transistors and related ones like the AF115 through AF117 were quite popular during the 1960s, but they quickly developed a reputation for failure. This is due to what should have made them more reliable, namely the can shielding the germanium transistor inside that is connected with a fourth ‘screen’ pin. This failure mode is demonstrated in a video by [Anthony Francis-Jones] in which he tests a number of new-old-stock AF-series transistors only for them all to test faulty and show clear whisker growth on the can’s exterior.

Naturally, the next step was to cut one of these defective transistors open to see whether the whiskers could be caught in the act. For this a pipe cutter was used on the fairly beefy can, which turned out to rather effective and gave great access to the inside of these 1960s-era components. The insides of the cans were as expected bristling with whiskers.

The AF11x family of transistors are high-frequency PNP transistors that saw frequent use in everything from consumer radios to just about anything else that did RF or audio. It’s worth noting that the material of the can is likely to be zinc and not tin, so these would be zinc whiskers. Many metals like to grow such whiskers, including lead, so the end effect is often a thin conductive strand bridging things that shouldn’t be. Apparently the can itself wasn’t the only source of these whiskers, which adds to the fun.

In the rest of the video [Anthony] shows off the fascinating construction of these germanium transistors, as well as potential repairs to remove the whisker-induced shorts through melting them. This is done by jolting them with a fairly high current from a capacitor. The good news is that this made the component tester see the AF114 as a transistor again, except as a rather confused NPN one. Clearly this isn’t an easy fix, and it would be temporary at best anyway, as the whiskers will never stop growing.

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Visiting Our Neighbor Sedna: Feasibility Study Of A Mission To This Planetoid

July 6, 2025 by Maya Posch 21 Comments

Image of Sedna, taken by the Hubble Space telescope in 2004. (Credit: NASA)

While for most people Pluto is the most distant planet in the Solar System, things get a lot more fuzzy once you pass Neptune and enter the realm of trans-Neptunian objects (TNOs). Pluto is probably the most well-known of these, but there are at least a dozen more of such dwarf planets among the TNOs, including 90377 Sedna.

This obviously invites the notion of sending an exploration mission to Sedna, much as was done with Pluto and a range of other TNOs through the New Horizons spacecraft. How practical this would be is investigated in a recent study by [Elena Ancona] and colleagues.

The focus is here on advanced propulsion methods, including nuclear propulsion and solar sails. Although it’s definitely possible to use a similar mission profile as with the New Horizons mission, this would make it another long-duration mission. Rather than a decades-long mission, using a minimally-equipped solar sail spacecraft could knock this down to about seven years, whereas the proposed Direct Fusion Drive (DFD) could do this in ten, but with a much larger payload and the ability do an orbital insertion which would obviously get much more science done.

As for the motivation for a mission to Sedna, its highly eccentric orbit that takes it past the heliopause means that it spends relatively little time being exposed to the Sun’s rays, which should have left much of the surface material intact that was present during the early formation of the Solar System. With our explorations of the Solar System taking us ever further beyond the means of traditional means of space travel, a mission to Sedna might not only expand our horizons, but also provide a tantalizing way to bring much more of the Solar System including the Kuiper belt within easy reach.

Why GitHub Copilot Isn’t Your Coding Partner

July 4, 2025 by Maya Posch 76 Comments

These days ‘AI’ is everywhere, including in software development. Coming hot on the heels of approaches like eXtreme Programming and Pair Programming, there’s now a new kind of pair programming in town in the form of an LLM that’s been digesting millions of lines of code. Purportedly designed to help developers program faster and more efficiently, these ‘AI programming assistants’ have primarily led to heated debate and some interesting studies.

In the case of [Jj], their undiluted feelings towards programming assistants like GitHub Copilot burn as brightly as the fire of a thousand Suns, and not a happy kind of fire.

Whether it’s Copilot or ChatGPT or some other chatbot that may or may not be integrated into your IDE, the frustration with what often feels like StackOverflow-powered-autocomplete is something that many of us can likely sympathize with. Although [Jj] lists a few positives of using an LLM trained on codebases and documentation, their overall view is that using Copilot degrades a programmer, mostly because of how it takes critical thinking skills out of the loop.

Regardless of whether you agree with [Jj] or not, the research so far on using LLMs with software development and other tasks strongly suggests that they’re not a net positive for one’s mental faculties. It’s also important to note that at the end of the day it’s still you, the fleshy bag of mostly salty water, who has to justify the code during code review and when something catches on fire in production. Your ‘copilot’ meanwhile gets off easy.

C++ Encounters Of The Rusty Zig Kind

July 1, 2025 by Maya Posch 83 Comments

There comes a time in any software developer’s life when they look at their achievements, the lines of code written and the programming languages they have relied on, before wondering whether there may be more out there. A programming language and its associated toolchains begin to feel like familiar, well-used tools after you use them for years, but that is no excuse to remain rusted in place.

While some developers like to zigzag from one language and toolset to another, others are more conservative. My own journey took me from a childhood with QuickBasic and VisualBasic to C++ with a bit of Java, PHP, JavaScript, D and others along the way. Although I have now for years focused on C++, I’m currently getting the hang of Ada in particular, both of which tickle my inner developer in different ways.

Although Java and D never quite reached their lofty promises, there are always new languages to investigate, with both Rust and Zig in particular getting a lot of attention these days. Might they be the salvation that was promised to us C-afflicted developers, and do they make you want to zigzag or ferrously oxidize?

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In Vivo CAR T Cell Generation For Cancer And Auto-Immune Treatments

July 1, 2025 by Maya Posch 1 Comment

With immunotherapy increasingly making it out of the lab and into hospitals as a viable way to treat serious conditions like cancer, there’s a lot of pressure to optimize these therapies. This is especially true for therapies involving chimeric antigen receptor (CAR) T cells, which so far required a cumbersome process of extracting the patient’s T cells, modifying them ex vivo and returning the now CAR T cells to the patient’s body. After a recently published study, it seems that we may see in vivo CAR T cell therapy become reality, with all the ease of getting a vaccine shot.

We covered CAR T cells previously in the context of a way to prevent T cell exhaustion and making them more effective against certain tumors. This new study (paywalled) by [Theresa L. Hunter] et al. as published in Science demonstrates performing the CAR manipulation in vivo using CD8+ T cell targeting lipid nanoparticles containing mRNA to reprogram these T cells directly.

In rodent and non-human primate studies a clear effect on tumor control was demonstrated, with for auto-immune diseases the related B cells becoming effectively depleted. Although it’s still a long way off from human trials and market approval, this research builds upon the knowledge gained from existing mRNA vaccines, raising hopes that one day auto-immune or cancer therapy could be as simple as getting a cheap, standardized shot.

Data Visualization And Aggregation: Time Series Databases, Grafana And More

June 30, 2025 by Maya Posch 12 Comments

If there’s one thing that characterizes the Information Age that we find ourselves in today, it is streams of data. However, without proper ways to aggregate and transform this data into information, it’ll either vanish into the ether or become binary blobs gathering virtual dust on a storage device somewhere. Dealing with these streams of data is thus essential, whether it’s in business (e.g. stock markets), IT (e.g. services status), weather forecasting, or simply keeping tracking of the climate and status of devices inside a domicile.

The first step of aggregating data seems simple, but rather than just writing it to a storage device until it runs out of space like a poorly managed system log, the goal here isn’t merely to record, but also to make it searchable. After all, for information transformation we need to be able to efficiently search and annotate this data, which requires keeping track of context and using data structures that lend themselves to this.

For such data aggregation and subsequent visualization of information on flashy dashboards that people like to flaunt, there are a few mainstream options, with among ‘smart home’ users options like InfluxDB and Grafana often popping up, but these are far from the only options, and depending on the environment there are much more relevant solutions.

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The 2025 Iberian Peninsula Blackout: From Solar Wobbles To Cascade Failures

June 30, 2025 by Maya Posch 70 Comments

Some Mondays are worse than others, but April 28 2025 was particularly bad for millions of people in Spain and Portugal. Starting just after noon, a number of significant grid oscillations occurred which would worsen over the course of minutes until both countries were plunged into a blackout. After a first substation tripped, in the span of only a few tens of seconds the effects cascaded across the Iberian peninsula as generators, substations, and transmission lines tripped and went offline. Only after the HVDC and AC transmission lines at the Spain-France border tripped did the cascade stop, but it had left practically the entirety of the peninsula without a functioning power grid. The event is estimated to have been the biggest blackout in Europe ever.

Following the blackout, grid operators in the affected regions scrambled to restore power, while the populace tried to make the best of being plummeted suddenly into a pre-electricity era. Yet even as power gradually came back online over the course of about ten hours, the question of what could cause such a complete grid collapse and whether it might happen again remained.

With recently a number of official investigation reports having been published, we have now finally some insight in how a big chunk of the European electrical grid suddenly tipped over.

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