About As Cold As It Gets: The Webb Telescope’s Cryocooler

May 5, 2022 by Dan Maloney 26 Comments

If you were asked to name the coldest spot in the solar system, chances are pretty good you’d think it would be somewhere as far as possible from the ultimate source of all the system’s energy — the Sun. It stands to reason that the further away you get from something hot, the more the heat spreads out. And so Pluto, planet or not, might be a good guess for the record low temperature.

But, for as cold as Pluto gets — down to 40 Kelvin — there’s a place that much, much colder than that, and paradoxically, much closer to home. In fact, it’s only about a million miles away, and right now, sitting at a mere 6 Kelvin, the chunk of silicon at the focal plane of one of the main instruments aboard the James Webb Space telescope makes the surface of Pluto look downright balmy.

The depth of cold on Webb is all the more amazing given that mere meters away, the temperature is a sizzling 324 K (123 F, 51 C). The hows and whys of Webb’s cooling systems are chock full of interesting engineering tidbits and worth an in-depth look as the world’s newest space telescope gears up for observations.

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EV Charging Connectors Come In Many Shapes And Sizes

April 28, 2022 by Lewin Day 69 Comments

Electric vehicles are now commonplace on our roads, and charging infrastructure is being built out across the world to serve them. It’s the electric equivalent of the gas station, and soon enough, they’re going to be everywhere.

However, it raises an interesting problem. Gas pumps simply pour a liquid into a hole, and have been largely standardized for quite some time. That’s not quite the case in the world of EV chargers, so let’s dive in and check out the current state of play.

AC, DC, Fast, or Slow?

Since becoming more mainstream over the past decade or so, EV technology has undergone rapid development. With most EVs still somewhat limited in range, automakers have developed ever-faster charging vehicles over the years to improve practicality. This has come through improvements to batteries, controller hardware, and software. Charging tech has evolved to the point where the latest EVs can now add hundreds of miles of range in under 20 minutes.

However, charging EVs at this pace requires huge amounts of power. Thus, automakers and industry groups have worked to develop new charging standards that can deliver high current to top vehicle batteries off as quickly as possible.

As a guide, a typical home outlet in the US can deliver 1.8 kW of power. It would take an excruciating 48 hours or more to charge a modern EV from a home socket like this.

In contrast, modern EV charge ports can carry anywhere from 2 kW up to 350 kW in some cases, and require highly specialized connectors to do so. Various standards have come about over the years as automakers look to pump more electricity into a vehicle at greater speed. Let’s take a look at the most common options out in the wild today. Continue reading “EV Charging Connectors Come In Many Shapes And Sizes” →

Noor III Solar Tower of the Ouarzazate Power Station, at dusk. (Credit: Marc Lacoste)

The Future Of Energy Storage On Both Sides Of The Meter

April 13, 2022 by Maya Posch 81 Comments

That energy storage is a hot topic is hardly a surprise to anyone these days. Even so, energy storage can take a lot of different forms, some of which are more relevant to the utility provider (like grid-level storage), while others are relevant to business and home owners (e.g. whole-house storage), and yet other technologies live in this tense zone between utility and personal interest, such as (electric) vehicle-to-grid.

For utilities a lot of noise is being made about shiny new technologies, such as hydrogen-based storage, while home- and business owners are pondering on the benefits of relying solely on the utility’s generosity with feed-in tariffs, versus charging a big battery from the solar panels on the roof and using the produced power themselves. Ultimately the questions here are which technologies will indeed live up to their promises, and which a home owner may want to invest in.

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Bath County Pumped Storage Station (Credit: CHA)

Grid-Level Energy Storage And The Challenge Of Storing Energy Efficiently

April 6, 2022 by Maya Posch 118 Comments

Although every electrical grid begins with the production of electricity, there are times when storing this power in some form instead of using it immediately is highly convenient. Today’s battery-powered gadgets are an obvious example of such time-shifting, but energy storage plays a major role on the grid itself, too, whether in electrochemical, mechanical or in some other form.

Utility-level energy storage is essential for not only stabilizing the grid, but also to time-shift excess energy and provide a way to deal with sudden spikes in demand (peak-shaving) plus demand drops by absorbing the excess energy. The health of the grid can essentially be regarded as a function of its alternating current (AC) frequency, with strong deviations potentially leading to a collapse of the grid.

Naturally, such energy storage is not free, and the benefits of adding it to the grid have to be considered against the expense, as well as potential alternatives. With the rapid increase of highly volatile electrical generators on the grid in the form of non-dispatchable variable renewable energy, e.g. wind turbines and PV solar, there has been a push to store more excess power rather than curtailing it, in addition to using energy storage for general grid health.

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Circuit VR: The Wheatstone Bridge Analog Computer

March 31, 2022 by Al Williams 13 Comments

We are always impressed with something so simple can actually be so complex. For example, what would you think goes into an analog computer? Of course, a “real” analog computer has opamps that can do logarithms, square roots, multiply, and divide. But would it surprise you that you can make an analog device like a slide rule using a Wheatstone bridge — essentially two voltage dividers. You don’t even need any active devices at all. It is an old idea and one that used to show up in electronic magazines now and again. I’ll show you how they work and simulate the device so you don’t have to build it unless you just want to.

A voltage divider is one of the easiest circuits in the world to analyze. Consider two resistors Ra and Rb in series. Voltage comes in at the top of Ra and the bottom of Rb is grounded. The node connecting Ra and Rb — let’s call it Z — is what we’ll consider the output.

Let’s say we have a 10 V battery feeding A and a perfect voltmeter that doesn’t load the circuit connected to Z. By Kirchoff’s current law we know the current through Ra and Rb must be the same. After all, there’s nowhere else for it to go. We also know the voltage drop across Ra plus the voltage drop across Rb must equal to 10 V. Kirchoff, conservation of energy, whatever you want to call it. Let’s call these quantities I, Va, and Vb. Continue reading “Circuit VR: The Wheatstone Bridge Analog Computer” →

Tech In Plain Sight: Car Doors

March 24, 2022 by Al Williams 54 Comments

There are a lot of common phrases that no longer mean what they used to. For example, you may have used the term “turn on the lights.” What are you actually turning? Where does this come from? Old gas lights had a valve that you did physically turn, and the phrase simply stuck around. Kids of the 90s have no idea why they “dial” a phone number. What about “roll up the car window”? You don’t often encounter old-fashioned car doors with manual locks or a crank to roll up the window. These days it is all electronic. But have you ever wondered what’s going on inside there?

Let’s take a look at car doors, how they keep you safe, and how that sheet of glass slides into place, sealing against wind, rain, and noise. Of course, there are fancy car doors like suicide doors or sexy-but-impractical gull wing doors. At least one concept car even has a door that disappears under the vehicle when it opens; check out the video below. But even garden-variety doors are marvels of mechanical engineering. A compact structure that is secure and — mostly — reliable. Let’s look at how they do that.

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3D Printing Concept Car (Parts)

March 23, 2022 by Al Williams 6 Comments

When you want to fabricate something you either start with something and take away what you don’t want — subtractive manufacturing — or you start with nothing and add material, which is additive manufacturing that we usually call 3D printing. Popular Science recently took a look inside Vital Auto, the British lab that uses 3D printing for high-end concept cars from companies like Rolls-Royce, McLauren, Jaguar, and others. In the video below, [Anthony Barnicott], an engineer for Vital, says that the two technologies — additive and subtractive — work best when used together.

As you might expect, they are not using a $200 FDM printer. They have three Formlabs 3Ls that print with resin and five Formlab Fuse 1 selective laser sintering printers. While metal printers are still uncommon in hacker’s workshops, resin printers are now very affordable although your garage printer is probably a good bit smaller than the 3L’s 335x200x300 mm volume. For comparison, an LCD-based AnyCubic Photon X provides just 165x132x80 mm. Of course, you’re looking at about $11,000 for the dual-laser 3L versus about $240 for the Photon.

Vital started building the EP9 electric car concept for NIO, an electric car maker in China. You can imagine that modern manufacturing machines make it possible to create more sophisticated concept cars faster. How many times do you want to tweak a part that takes a machinist eight hours to produce? But if you can just let a machine run overnight and get the result in the morning, you are more likely to change and refine the part.

Vital Auto is an interesting look at how professional fabrication shops are using the same technologies we do, at least at the core. We’ve noted before how these same technologies are making homebrew projects look better than some commercial products not long ago. You can print big things if you break them up, of course. Or, break the bank and buy a really big printer.

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