The DEW Line Remembered

July 16, 2025 by Al Williams 18 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” →

Caltech Scientists Make Producing Plastics From CO2 More Efficient

July 16, 2025 by Maya Posch 26 Comments

For decades there has been this tantalizing idea being pitched of pulling CO₂ out of the air and using the carbon molecules for something more useful, like making plastics. Although this is a fairly simple process, it is also remarkably inefficient. Recently Caltech researchers have managed to boost the efficiency somewhat with a new two-stage process involving electrocatalysis and thermocatalysis that gets a CO₂ utilization of 14%, albeit with pure CO₂ as input.

The experimental setup with the gas diffusion electrode (GDE) and the copolymerization steps. (Credit: Caltech)

The full paper as published in Angewandte Chemie International is sadly paywalled with no preprint available, but we can look at the Supplemental Information for some details. We can see for example the actual gas diffusion cell (GDE) starting on page 107 in which the copper and silver electrodes react with CO₂ in a potassium bicarbonate (KHCO₃) aqueous electrolyte, which produces carbon monoxide (CO) and ethylene (C₂H₄). These then react under influence of a palladium catalyst in the second step to form polyketones, which is already the typical way that these thermoplastics are created on an industrial scale.

The novelty here appears to be that the ethylene and CO are generated in the GDEs, which require only the input of CO₂ and the potassium bicarbonate, with the CO2 recirculated for about an hour to build up high enough concentrations of CO and C₂H₄. Even so, the researchers note a disappointing final quality of the produced polyketones.

Considering that a big commercial outfit like Novomer that attempted something similar just filed for Chapter 11 bankruptcy protection, it seems right to be skeptical about producing plastics on an industrial scale, before even considering using atmospheric CO₂ for this at less than 450 ppm.

Arduino Saves Heat Pump

July 16, 2025 by Bryan Cockfield 28 Comments

For home HVAC systems, heat pumps seem to be the way of the future. When compared to electric heating they can be three to four times more efficient, and they don’t directly burn fossil fuels. They also have a leg up over standard air conditioning systems since they can provide both cooling and heating, and they can even be used on water heating systems. Their versatility seems unmatched, but it does come at a slight cost of complexity as [Janne] learned while trying to bring one back to life.

The heat pump here is a Samsung with some physical damage, as well as missing the indoor half of the system. Once the damage to the unit was repaired and refilled with refrigerant, [Janne] used an Optidrive E3 inverter controlled by an Arduino Mega to get the system functional since the original setup wouldn’t run the compressor without the indoor unit attached. The Arduino manages everything else on the system as well including all of the temperature sensors and fan motor control.

With everything up and running [Janne] connected the system to a swimming pool, which was able to heat the pool in about three hours using 60 kWh of energy. The system is surprisingly efficient especially compared to more traditional means of heating water, and repairing an old or damaged unit rather than buying a new one likely saves a significant amount of money as well. Heat pump projects are getting more common around here as well, and if you have one in your home take a look at this project which adds better climate control capabilities. to a wall mount unit.

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.

View inside the vacuum vessel of Wendelstein 7-X in Greifswald, Germany. (Credit: Jan Hosan, MPI for Plasma Physics)

Wendelstein 7-X Sets New Record For The Nuclear Fusion Triple Product

July 15, 2025 by Maya Posch 36 Comments

Fusion product against duration, showing the Lawson criterion progress. (Credit: Dinklage et al., 2024, MPI for Plasma Physics)

In nuclear fusion, the triple product – also known as the Lawson criterion – defines the point at which a nuclear fusion reaction produces more power than is needed to sustain the fusion reaction. Recently the German Wendelstein 7-X stellarator managed to hit new records here during its most recent OP 2.3 experimental campaign, courtesy of a frozen hydrogen pellet injector developed by the US Department of Energy’s Oak Ridge National Laboratory. With this injector the stellarator was able to sustain plasma for over 43 seconds as microwaves heated the freshly injected pellets.

Although the W7-X team was informed later that the recently decommissioned UK-based JET tokamak had achieved a similar triple product during its last – so far unpublished – runs, it’s of note that the JET tokamak had triple the plasma volume. Having a larger plasma volume makes such an achievement significantly easier due to inherently less heat loss, which arguably makes the W7-X achievement more noteworthy.

The triple product is also just one of the many ways to measure progress in commercial nuclear fusion, with fusion reactors dealing with considerations like low- and high-confinement mode, plasma instabilities like ELMs and the Greenwald Density Limit, as we previously covered. Here stellarators also seem to have a leg up on tokamaks, with the proposed SQuID stellarator design conceivably leap-frogging the latter based on all the lessons learned from W7-X.

Top image: Inside the vacuum vessel of Wendelstein 7-X. (Credit: Jan Hosan, MPI for Plasma Physics)

USB-C Rainbow Ranger: Sensing Volts With Style

July 15, 2025 by Matt Varian 1 Comment

USB-C has enabled a lot of great things, most notably removing the no less than three attempts to plug in the cable correctly, but gone are the days of just 5V over those lines. [Meticulous Technologies] sent in their project to help easily identify what voltage your USB-C line is running at, the USB VSense.

The USB VSense is an inline board that has USB-C connectors on either end, and supporting up to 240W you don’t have to worry about it throttling your device. One of the coolest design aspects of this board is that it uses stacked PCB construction as the enclosure, the display, and the PCB doing all the sensing and displaying. And for sensing this small device has a good number of cool tricks, it will sense all the eight common USB-C voltages, but it will also measure and alert you to variations of the voltage outside the normal range by blinking the various colored LEDs in specific patterns. For instance should you have it plugged into a line that’s sitting over 48V the VSense white 48V LED will be rapidly blinking, warning you that something in your setup has gone horribly wrong.

Having dedicated uniquely colored LEDs for each common level allows you to at a glance know what the voltage is at without the need to read anything. With a max current draw of less than 6mA you won’t feel bad about using it on a USB battery pack for many applications.

The USB VSense has completed a small production run and has stated their intention to open source their design as soon as possible after their Crowd Supply campaign. We’ve featured other USB-C PD projects and no doubt we’ll be seeing more as this standard continues to gain traction with more and more devices relying on it for their DC power.

Pulling At Threads With The Flipper Zero

July 15, 2025 by Adam Zeloof 13 Comments

Gone are the days when all smart devices were required an internet uplink. The WiFi-enabled IoT fad, while still upon us (no, my coffee scale doesn’t need to be on the network, dammit!) has begun to give way to low-power protocols actually designed for this kind of communication, such as ZigBee, and more recently, Thread. The downside of these new systems, however, is that they can be a bit more difficult in which to dabble. If you want to see just why your WiFi-enabled toaster uploads 100 MB of data per day to some server, you can capture some network traffic on your laptop without any specialized hardware. These low-power protocols can feel a bit more opaque, but that’s easily remedied with a dev board. For a couple of dollars, you can buy Thread radio that, with some additional hacking, acts as a portal between this previously-arcane protocol and your laptop — or, as [András Tevesz] has shown us, your Flipper Zero.

He’s published a wonderful three-part guide detailing how to mod one such $10 radio to communicate with the Flipper via its GPIO pins, set up a toolchain, build the firmware, and start experimenting. The guide even gets into the nitty-gritty of how data is handled transmitted and investigates potential attack vectors (less worrying for your Thread-enabled light bulb, very worrying for your smart door lock). This project is a fantastic way to prototype new sensors, build complicated systems using the Flipper as a bridge, or even just gain some insight into how the devices in your smart home operate.

In 2025, it’s easier than ever to get started with home automation — whether you cook up a solution yourself, or opt for a stable, off-the-shelf (but still hackable) solution like HomeAssistant (or even Minecraft?). Regardless of the path you choose, you’ll likely wind up with devices on the Thread network that you now have the tools to hack.