Practical Sensors: The Many Ways We Measure Heat Electronically

February 19, 2021 by Al Williams 24 Comments

Measuring temperature turns out to be a fundamental function for a huge number of devices. You furnace’s programmable thermostat and digital clocks are obvious examples. If you just needed to know if a certain temperature is exceeded, you could use a bimetalic coil and a microswitch (or a mercury switch as was the method with old thermostats). But these days we want precision over a range of readings, so there are thermocouples that generate a small voltage, RTDs that change resistance with temperature, thermistors that also change resistance with temperature, infrared sensors, and vibrating wire sensors. The bandgap voltage of a semiconductor junction varies with temperature and that’s predictable and measurable, too. There are probably other methods too, some of which are probably pretty creative.

Bimetalic coil by [Hustvede], CC-BY-SA 3.0.

You can often think of creative ways to do any measurement. There’s an old joke about the smart-alec student in physics class. The question was how do you find the height of a building using a barometer. One answer was to drop the barometer from the top of the building and time how long it takes to hit the ground. Another answer — doubtlessly an engineering student — wanted to find the building engineer and offer to give them the barometer in exchange for the height of the building. By the same token, you could find the temperature by monitoring a standard thermometer with a camera or even a level sensor which is a topic for another post.

The point is, there are plenty of ways to measure anything, but in every case, you are converting what you want to know (temperature) into something you know how to measure like voltage, current, or physical position. Let’s take a look at how some of the most interesting temperature sensors accomplish this.

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A Brief History Of Optical Communication

February 18, 2021 by Moritz v. Sivers 44 Comments

We live in the information age where access to the internet is considered a fundamental human right. Exercising this right does largely rely on the technological advances made in optical communication. Using light to send information has a long history: from ancient Greece, through Claude Chappe’s semaphore towers and Alexander Graham Bell’s photophone, to fiber optic networks and future satellite internet constellations currently developed by tech giants.

Let’s dive a little bit deeper into the technologies that were used to spread information with the help of light throughout history. Continue reading “A Brief History Of Optical Communication” →

NASA Selects SpaceX To Launch Lunar Gateway

February 18, 2021 by Tom Nardi 37 Comments

While not a Cabinet position, the NASA Administrator is nominated by the president of the United States and tasked with enacting their overall space policy. As such, a new occupant in the White House has historically resulted in a different long-term directive for the agency. Some presidents have wanted bold programs of exploration, while others have directed NASA to follow a more reserved and economical path, with the largest shifts traditionally happening when the administration changes hands between the parties.

So it’s no surprise that the fate of Artemis, a bold program initiated by the previous administration that aims to establish a sustainable human presence on the Moon, has been considered uncertain since the November election. But the recent announcement that SpaceX has been awarded a $331.8 million contract to launch the first two modules of the lunar Gateway station, an orbital outpost that will serve as a rallying point for astronauts coming and going to the Moon’s surface, should help quell some concerns. While the components still aren’t slated to fly until 2024 at the earliest, it’s a step in the right direction and strong indicator that the new administration plans on seeing Artemis through.

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Trouble With The Texas Power Grid As Cold Weather Boosts Demand, Knocks Out Generators

February 16, 2021 by Jenny List 253 Comments

It comes as something of a shock that residents of the Lone Star State are suffering from rolling power blackouts in the face of an unusually severe winter. First off, winter in Texas? Second, isn’t it the summer heat waves that cause the rolling blackouts in that region?

Were you to mention Texas to a European, they’d maybe think of cowboys, oil, the hit TV show Dallas, and if they were European Hackaday readers, probably the semiconductor giant Texas Instruments. The only state of the USA with a secession clause also turns out to to have their own power grid independent of neighboring states.

An accurate and contemporary portrait of a typical Texan, as understood by Europeans. Carol M. Highsmith, Public domain.

Surely America is a place of such resourcefulness that this would be impossible, we cry as we watch from afar the red squares proliferating across the outage map. It turns out that for once the independent streak that we’re told defines Texas may be its undoing. We’re used to our European countries being tied into the rest of the continental grid, but because the Texan grid stands alone it’s unable to sip power from its neighbours in times of need.

Let’s dive into the mechanics of maintaining an electricity grid, with the unfortunate Texans for the moment standing in as the test subject.

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BASIC: Cross-Platform Software Hacking Then And Now

February 16, 2021 by Maya Posch 125 Comments

Surely BASIC is properly obsolete by now, right? Perhaps not. In addition to inspiring a large part of home computing today, BASIC is still very much alive today, even outside of retro computing.

There was a time, not even that long ago, when the lingua franca of the home computer world was BASIC. This wasn’t necessarily always the exact same BASIC; the commands and syntax differed between whatever BASIC dialect came with any given model of home computer (Commodore, Atari, Texas Instruments, Sinclair or any of the countless others). Fortunately most of these licensed or were derived from the most popular microcomputer implementation of BASIC: Microsoft BASIC.

BASIC has its roots in academics, where it was intended to be an easy to use programming language for every student, even those outside the traditional STEM fields. Taking its cues from popular 1960s languages like FORTRAN and ALGOL, it saw widespread use on time-sharing systems at schools, with even IBM joining the party in 1973 with VS-BASIC. When the 1970s saw the arrival of microcomputers, small and cheap enough to be bought by anyone and used at home, it seemed only natural that they too would run BASIC.

The advantage of having BASIC integrated into these systems was obvious: not only were most people who bought such a home computer already familiar with BASIC, it allows programs to be run without first being compiled. This was good, because compiling a program takes a lot of RAM and storage, neither of which were plentiful in microcomputers. Instead of compiling BASIC source code, BASIC interpreters would interpret and run the code one line at a time, trading execution speed for flexibility and low resource use.

After turning on one’s microcomputer, the BASIC interpreter would usually be loaded straight from an onboard ROM in lieu of a full-blown operating system. In this interpreter shell, one could use the hardware, write and load BASIC programs and save them to tape or disk. Running existing BASIC code as well as compiled programs on one’s computer, or even typing them in from a listing in a magazine all belonged to the options. As BASIC implementations between different home computers were relatively consistent, this provided for a lot of portability.

That was then, and this is now. Are people actually still using the Basic language?

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The Rotary-X Engine Is A Revolution In Thermodynamics

February 15, 2021 by Kristina Panos 119 Comments

If you’re running an army, chances are good that you need a lot of portable power for everything from communications to weapons control systems. When it comes to your generators, every ounce counts. The smaller and lighter you can get them, the better.

Connecticut-based company LiquidPiston is developing a high-powered generator for the US Army that uses the company’s own rotary x-engine — a small, light, and powerful beast that sounds like a dream come true. It can run on gasoline, diesel, natural gas, kerosene, or jet fuel, and is scalable from 1 to 1,000 horsepower (PDF).

Co-founder and CEO Alex Schkolnik describes the design as a combination of the best parts of the Otto and Atkinson cycle engines, the Diesel, and the Wankel rotary while solving the big problems of the latter two. That sounds impressive, but it doesn’t mean much unless you understand how each of these engines work and what their various advantages and disadvantages are. So let’s take a look under the hood, shall we?

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Europa Decision Delivers Crushing Blow To NASA’s Space Launch System (SLS)

February 12, 2021 by Tom Nardi 110 Comments

These days, NASA deciding to launch one of their future missions on a commercial rocket is hardly a surprise. After all, the agency is now willing to fly their astronauts on boosters and spacecraft built and operated by SpaceX. Increased competition has made getting to space cheaper and easier than ever before, so it’s only logical that NASA would reap the benefits of a market they helped create.

So the recent announcement that NASA’s Europa Clipper mission will officially fly on a commercial launch vehicle might seem like more of the same. But this isn’t just any mission. It’s a flagship interplanetary probe designed to study and map Jupiter’s moon Europa in unprecedented detail, and will serve as a pathfinder for a future mission that will actually touch down on the moon’s frigid surface. Due to the extreme distance from Earth and the intense radiation of the Jovian system, it’s considered one of the most ambitious missions NASA has ever attempted.

With no margin for error and a total cost of more than $4 billion, the fact that NASA trusts a commercially operated booster to carry this exceptionally valuable payload is significant in itself. But perhaps even more importantly, up until now, Europa Clipper was mandated by Congress to fly on NASA’s Space Launch System (SLS). This was at least partly due to the incredible power of the SLS, which would have put the Clipper on the fastest route towards Jupiter. But more pragmatically, it was also seen as a way to ensure that work on the Shuttle-derived super heavy-lift rocket would continue at a swift enough pace to be ready for the mission’s 2024 launch window.

But with that deadline fast approaching, and engineers feeling the pressure to put the final touches on the spacecraft before it gets mated to the launch vehicle, NASA appealed to Congress for the flexibility to fly Europa Clipper on a commercial rocket. The agency’s official line is that they can’t spare an SLS launch for the Europa mission while simultaneously supporting the Artemis Moon program, but by allowing the Clipper to fly on another rocket in the 2021 Consolidated Appropriations Act, Congress effectively removed one of the only justifications that still existed for the troubled Space Launch System.

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