This SSD Will Self Destruct In Ten Seconds…

July 16, 2025 by Al Williams 16 Comments

In case you can’t wait for your flash memory to die from write cycling, TeamGroup now has a drive that, via software or hardware, can destroy its own flash chips with a surge of voltage. If you wonder why you might want this, there are military applications where how you destroy a piece of equipment is right up there in the manual with how to use it.

They have obviously put a lot of thought into it, as you can see in the video below. Apparently, if you are in the middle of blowing up the flash and power cuts out, the chip will resume frying itself when you restore power.

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The DEW Line Remembered

July 16, 2025 by Al Williams 19 Comments

The DEW line was one of three radar early warning systems of the time.

If you grew up in the middle of the Cold War, you probably remember hearing about the Distant Early Warning line between duck-and-cover drills. The United States and Canada built the DEW line radar stations throughout the Arctic to detect potential attacks from the other side of the globe.

MIT’s Lincoln Lab proposed the DEW Line in 1952, and the plan was ambitious. In order to spot bombers crossing over the Arctic circle in time, it required radar twice as powerful as the best radar of the day. It also needed communications systems that were 99 percent reliable, even in the face of terrestrial and solar weather.

In the end, there were 33 stations built from Alaska to Greenland in an astonishing 32 months. Keep in mind that these stations were located in a very inhospitable environment, where temperatures reached down to -60 °F (-51 °C). Operators kept the stations running 24/7 for 36 years, from 1957 to 1993.

System of Systems

The DEW line wasn’t the only radar early-warning system that the US and Canada had in place, only the most ambitious. The Pinetree Line was first activated in 1951. However, its simple radar was prone to jamming and couldn’t pick up things close to the ground. It was also too close to main cities along the border to offer them much protection. Even so, the 33 major stations, along with six smaller stations, did better than expected. Continue reading “The DEW Line Remembered” →

A History Of The Tandy Computers

July 15, 2025 by Al Williams 22 Comments

Radio Shack, despite being gone for a number of years, is still in our cultural consciousness. But do you know Tandy? And did you ever wonder how a leather company that started in 1919 became, briefly, a computer giant? Or even an electronics retailer? [Abort Retry Fail] has the story in three parts, framed with their computers. Well, three parts so far. They are only up to the Tandy 1000.

At first, the company made parts for shoes. But after World War II, they found that catering to leather crafting hobbyists was lucrative. Within a few years, they’d opened stores across the country, making sure that the store managers owned 25% of their stores, even if it meant they had to borrow money from the home office to do so. Meanwhile, Radio Shack was in Boston selling to radio amateurs. By 1935, Radio Shack was a corporation. In 1954, they started selling “Realist” brand equipment, that we would come to know as Realistic.

In 1961, Tandy decided to branch out into other hobby markets, including radio hobbyists. But Radio Shack, dabbling in consumer credit, was sunk with $800,000 of uncollectable consumer credit.

In 1963, Tandy purchased the struggling Radio Shack for $300,000, which was a substantial amount of money in those days. Tandy immediately set about making Radio Shack profitable. Tandy would eventually split into three companies, spinning off its original leather and craft businesses.

Then came computers. If you are at all interested in the history of early computers, the TRS-80, or any of the other Radio Shack computers, you’ll enjoy the story. It wasn’t all smooth sailing. We can’t wait to read part four, although sadly, we know how the story ends.

We don’t just miss the Radio Shack computers. We loved P-Box kits. Yeah, we know someone bought the brand. But if you visit the site, you’ll see it just isn’t the same.

A Collection Of Lightning Detectors

July 15, 2025 by Al Williams 20 Comments

You would think detecting lightning would be easy. Each lightning bolt has a staggering amount of power, and, clearly, you can hear the results on any radio. But it is possible to optimize a simple receiver circuit to specifically pick up lightning. That’s exactly what [Wenzeltech] shows in a page with several types of lightning detectors complete with photos and schematics.

Just as with a regular radio, there are multiple ways to get the desired result. The first circuits use transistors. Later versions move on to op amps and even have “storm intensity” meters. The final project uses an ion chamber from a smoke detector. It has the benefit of being very simple, but you know, also slightly radioactive.

You might think you could detect lightning by simply looking out the window. While that’s true, you can, in theory, detect events from far away and also record them easily using any data acquisition system on a PC, scope, or even logic analyzer.

Why? We are sure there’s a good reason, but we’ve never needed one before. These designs look practical and fun to build, and that’s good enough for us.

You can spruce up the output easily. You can also get it all these days, of course, on a chip.

Record Changer Spins Round And Round

July 14, 2025 by Al Williams 1 Comment

There was a time when all the cool kids had a 45 RPM record player. [RF Burns] picked up a 1950s-era player from RCA. However, it needed a lot of work. The good news? We get to see the teardown and the result in a two-part video series, which you can see below. If you are looking for the schematic, you’ll have to wait for the second video.

These were made to be cheap, so there were many parts that needed replacement or, at least TLC. The automation of the record changer was all done with an eccentric wheel, which is satisfyingly low-tech. We were surprised that it still seemed to work after everything was cleaned up.

Inside were two active tubes and a rectifier tube to amplify the signal from the needle. A coat of paint made it look great, and a polarized power cord made it safer.

There was also an unamplified version of the player you can see at the end of the second video. All the same things except for the tube amplifier, of course.

If you are too young to have fond memories of 45s, here’s a primer on how records work. The record player we really want is mobile.

Robots Want The Jobs You Can’t Do

July 14, 2025 by Al Williams 11 Comments

There’s something ominous about robots taking over jobs that humans are suited to do. Maybe you don’t want a job turning a wrench or pushing a broom, but someone does. But then there are the jobs no one wants to do or physically can’t do. Robots fighting fires, disarming bombs, or cleaning up nuclear reactors is something most people will support. But can you climb through a water pipe from the inside? No? There are robots that are available from several commercial companies and others from university researchers from multiple continents.

If you think about it, it makes sense. For years, companies that deal with pipes would shoot large slugs, or “pigs”, through the pipeline to scrape them clean. Eventually, they festooned some pigs with sensors, and thus was born the smart pig. But now that it is possible to make tiny robots, why not send them inside the pipe to inspect and repair?

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Coroutines In C

July 14, 2025 by Al Williams 20 Comments

It is virtually a rite of passage for C programmers to realize that they can write their own cooperative multitasking system. C is low-level enough, and there are several ways to approach the problem, so, like Jedi light sabers, each one is a little bit different. [Christoph Wolcher] took his turn, and not only is his system an elegant hack, if that’s not an oxymoron, it is also extremely well documented.

Before you dig in, be warned. [Christoph] fully admits that you should use an RTOS. Or Rust. Besides, after he finished, he discovered the protothreads library, which does a similar task in a different way that is both more cool and more terrible all at the same time.

Once you dig in, though, you’ll see the system relies on state machines. Just to prove the point, he writes a basic implementation, which is fine, but hard to parse and modify. Then he shows a simple implementation using FreeRTOS, which is fine except for, you know, needing FreeRTOS.

Using a simple set of macros, it is possible to get something very similar to the RTOS version that runs independently, like the original version. Most of the long code snippets show you what code the macros generate. The real code is short and to the point.

Multiprocessing is a big topic. You can have processes, threads, fibers, and coroutines. Each has its pros and cons, and each has its place in your toolbox.