Wireless Charging On A Massive Scale

March 21, 2023 by Bryan Cockfield 26 Comments

Despite the increasing popularity of various electric vehicles, the limits of battery technology continue to be a bottleneck in their day-to-day use. They don’t behave well in extreme temperatures, they can wear out quickly, and, perhaps most obviously, charging them is often burdensome. Larger batteries take longer to charge, and this can take a lot of time and space, but this research team from Chalmers University are looking to make this process just a little bit easier.

The group has been developing an inductive wireless charging method for large vehicles including cars, trucks, busses, and ferries that can deliver 500 kW across a 15 cm (6 inch) air gap. The system relies on a silicon carbide semiconductor and extremely thin copper wire in order to make all this happen, and eliminates the need for any human involvement in the charging process. This might not be too much of a hassle for plugging in an electric car, but for larger vehicles like busses and ferries traditional charging methods often require a robot arm or human to attach the charging cables.

While this technology won’t decrease the amount of time it takes batteries to charge, it will improve the usability of devices like these. Even for cars, this could mean simply pulling into a parking space and getting the car’s battery topped off automatically. For all the talk about charging times of batteries, there is another problem looming which is that plenty of charging methods are proprietary as well. This charger attempts to develop an open-source standard instead.

Thanks to [Ben] for the tip!

Frequency Tells Absolute Temperature

January 18, 2023 by Al Williams 21 Comments

It is no secret that semiconductor junctions change their behavior with temperature, and you can use this fact to make a temperature sensor. The problem is that you have to calibrate each device for any particular transistor you want to use as a sensor, even if they have the same part number. Back in ~~2011~~ 1991, the famous [Jim Williams] noted that while the voltage wasn’t known, the difference between two readings at different current levels would track with temperature in a known way. He exploited this in an application note and, recently, [Stephen Woodward] used the same principle in an oscillator that can read the temperature.

The circuit uses an integrator and a comparator. A FET switches between two values of collector current. A comparator drives the FET and also serves as the output. Rather than try to puzzle out the circuit just from the schematic, you can easily simulate it with LT Spice or Falstad. The Falstad simulator doesn’t have a way to change the temperature, but you can see it operating. The model isn’t good enough to really read a temperature, but you can see how the oscillation works

You can think of this as a temperature-to-frequency converter. It would be easy to read with, say, a microcontroller and convert the period to temperature. Every 10 microseconds is equal to a degree Kelvin. Not bad for something you don’t have to calibrate.

Thermistors are another way to measure temperature. Sometimes, you don’t need a sensor at all.

Hackaday Links: November 6, 2022

November 6, 2022 by Dan Maloney 20 Comments

Remember the chip shortage? We sure do, mainly because as far as we can tell, it’s still going on, at least judging by the fact that you can’t get a Raspberry Pi for love or money. But that must just be noise, because according to a report in the Straits Times, the chip shortage is not only over, it’s reversed course enough that there’s now a glut of semiconductors out there. The article claims that the root cause of this is slowing demand for products like smartphones, an industry that’s seeing wave after wave of orders to semiconductor manufacturers like TSMC canceled. Chips for PCs are apparently in abundance now too, as the spasm of panic buying machine for remote working during the pandemic winds down. Automakers are still feeling the pinch, though, so much so that Toyota is now shipping only one smart key with new cars, instead of the usual two. So there seems to be some way to go before balance is restored to the market, but whatever — just call us when Amazon no longer has to offer financing on an 8 GB Pi.

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Copper: Rectifying AC A Century Ago

April 20, 2022 by Dave Rowntree 32 Comments

[Robert Murray-Smith] presents for us an interesting electronic device from years gone by, before the advent of Silicon semiconductors, the humble metal oxide rectifier. After the electronic dust had settled following the brutal AC/DC current wars of the late 19th century — involving Edison, Tesla and Westinghouse to name a few of the ringleaders — AC was the eventual winner. But there was a problem. It’s straightforward to step down the high voltage AC from the distribution network to a more manageable level with a transformer, and feed that straight into devices which can consume alternating current such as light bulbs and electrical heaters. But other devices really want DC, and to get that, you need a rectifier.

It turns out, that even in those early days, we had semiconductor devices which could perform this operation, based not upon silicon or germanium, but copper. Copper (I) Oxide is a naturally occurring P-type semiconductor, which can be easily constructed by heating a copper sheet in a flame, and scraping off the outer layer of Copper (II) Oxide leaving the active layer below. Simply making contact to a piece of steel is sufficient to complete the device.

Obviously a practical rectifier is a bit harder to make, with a degree of control required, but you get the idea. A CuO metal rectifier can rectify as well as operate as a thermopile, and even as a solar cell, it’s just been forgotten about once we got all excited about silicon.

Other similar metallic rectifiers also saw some action, such as the Selenium rectifier, based on the properties of a Cadmium Selenide – Selenium interface, which forms an NP junction, albeit one that can’t handle as much power as good old copper. One final device, which was a bit of an improvement upon the original CuO rectifiers, was based upon a stack of Copper Sulphide/Magnesium metal plates, but they came along too late. Once we discovered the wonders of germanium and silicon, it was consigned to the history books before it really saw wide adoption.

We’ve covered CuO rectifiers before, but the Copper Sulphide/Magnesium rectifier is new to us. And if you’re interested in yet more ways to steer electrons in one direction, checkout our coverage of the history of the diode.

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What Goes Into A High Voltage Diode?

October 3, 2021 by Jenny List 12 Comments

When we use an electronic component, we have some idea of what goes on inside it. We know that inside a transistor there’s a little piece of semiconductor with a junction made from differently doped regions etched into it, and in a capacitor, there will be metalized plates on the surface of some kind of dielectric. Reverse engineering has given us extensive die photography of integrated circuits, but there remain a few component mysteries to be uncovered. One is laid bare by [WizardTim], as he cross-sections a 20KV high-voltage diode.

A conventional low-voltage silicon diode has a forward voltage drop of about 0.7V and a relatively low maximum reverse voltage, for example with the 1N4001 rectifier it’s 50V. For the higher-spec 1N4007, the reverse voltage rating is 700V. This diode has a 25KV reverse voltage, and a clue to its construction comes in its quoted 45V forward voltage. Sure enough, when mounted in resin and carefully sanded and polished flat it reveals its interior as a stack of diodes in series to increase the reverse voltage at the expense of forward voltage.

Revealing the inner workings of an unusual component is fascinating, and the lapping technique used is definitely worth a look. It’s something we’ve seen before, for example in reducing CPU thickness for increased performance.

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Hackaday Links: August 15, 2021

August 15, 2021 by Dan Maloney 13 Comments

Unless you’re in the market for a new car, household appliance, or game console, or if you’re involved in the manufacture of these things, chances are pretty good that the global semiconductor shortage hasn’t directly impacted you yet. But we hobbyists might be due for a comeuppance as the chip shortage starts to impact our corner of the market. We suppose it’s natural that supplies of the chips needed to build Arduinos and Raspberry Pis would start to dry up, as semiconductor manufacturers realign their resources to service their most lucrative markets. Still, it was all sort of abstract until now, but seeing dire quotes from the likes of Adafruit, Pololu, and Sparkfun about the long lead times they’re being quoted — some chips won’t be seen until 2023! — is disheartening. As are the reports of price gouging and even hoarding; when a $10 part can suddenly command $350, you know something has gone seriously wrong.

But have no fear — we’re certain the global chip shortage will have no impact on the planned 2027 opening of the world’s first space hotel. Voyager Station — once dubbed Von Braun Station but renamed for some reason — looks for all the world like Space Station V in “2001: A Space Odyssey”, or at least half of it. The thing is enormous — witness the Starship docked in the center hub, as well as the several dozen shuttle-like craft — escape pods, perhaps? — attached to the outer rim. The renders are imaginative, to say the least — the station looks very sleek, completely unfettered by such banalities as, say, solar panels. We get that a private outfit needs to attract deep-pocketed investors, and that one doesn’t do that by focusing on the technical details when they can sell a “premium experience”. But really, if you’re going to space, do you want basically the same look and feel as a premium hotel on Earth, just with a better view? Or would you rather feel like you’ve actually traveled to space?

Speaking of space, did you ever wonder what the first programmable calculator in space was? Neither did we, but that doesn’t mean we didn’t find this detailed story about the HP-65 that was sent up on the Apollo-Soyuz Test Project in 1975 pretty fascinating. The ASTP was the last hurrah of Apollo, and an often underappreciated engineering challenge. Linking up the two spacecraft safely was not trivial, and a fair number of burn calculations had to be made in orbit to achieve rendezvous and docking, as well as to maintain orbit. The HP-65, a programmable calculator that went for about $750 at the time (for the non-space-rated version, of course) had several programs loaded onto its removable magnetic cards, and the Apollo crew used it to verify the results calculated by the Apollo Guidance Computer (AGC).

Facebook, a company that exists by providing people with a product they don’t need but now somehow can’t live without, is now dipping a toe into weird, weird waters: reverse-passthrough virtual reality. The idea, we take it, is that as users more widely adopt VR and integrate it into their daily lives, the VR headsets everyone will be wearing will make face-to-face contact more difficult. So what better way to solve that problem than by projecting a live image of the VR user’s eyes onto a screen outside the VR rig, for any and all to see? Pure genius, and not the least bit creepy. They’ve perhaps got a bit of work to go before achieving their goal of “seamless social connection between real and virtual worlds”.

And speaking of eyes, it’s good to know that developers are still hard at work keeping the most vital applications running at peak efficiency on today’s hardware. Yes, the venerable XEyes, a program for the X Window System on Unix-like operating systems that draws a pair of googly eyes on the screen to follow your mouse movements, has finally moved to version 1.2.0. It’s been 11 years since the 1.1.0 upgrade, so it was a long time coming. If you haven’t had the chance to play with XEyes, fear not — just about any Linux machine should be able to show you what you’ve been missing. Or, you know, you could even run it on a camera as the video below the break shows.

Continue reading “Hackaday Links: August 15, 2021” →

Hackaday Links: July 18, 2021

July 18, 2021 by Dan Maloney 12 Comments

Tell the world that something is in short supply, and you can bet that people will start reacting to that news in the ways that make the most sense to them — remember the toilet paper shortage? It’s the same with the ongoing semiconductor pinch, except that since the item in short supply is (arguably) more valuable than toilet paper, the behavior and the risks people are willing to take around it are even more extreme. Sure, we’ve seen chip hoarding, and a marked rise in counterfeit chips. But we’d imagine that this is the first time we’ve seen chip smuggling quite like this. The smuggler was caught at the Hong Kong-Macao border with 256 Core i7 and i9 processors, valued at about $123,000, strapped to his legs and chest. It reminds us more of “Midnight Express”-style heroin smuggling, although we have to say we love the fact that this guy chose a power of 2 when strapping these babies on.

Speaking of big money, let’s say you’ve pulled off a few chip heists without getting caught, and have retired from the smuggling business. What is one to do with the ill-gotten gains? Apparently, there’s a big boom in artifacts from the early days of console gaming, so you might want to start spreading some money around there. But you’d better prepare to smuggle a lot of chips: last week, an unopened Legend of Zelda cartridge for the NES sold for $870,000 at auction. Not to be outdone, two days later someone actually paid $1.56 million for a Super Mario 64 cartridge, this time apparently still in the tamperproof container that displayed it on a shelf somewhere in 1996. Nostalgia can be an expensive drug.

And it’s not just video games that are commanding high prices these days. If you’ve got a spare quarter million or so, why not bid on this real Apollo Guidance Computer and DSKY? The AGC is a non-flown machine that was installed in LTA-8, the “lunar test article” version of the Landing Module (LM) that was used for vacuum testing. If the photos in the auction listing seem familiar, it’s with good reason: this is the same AGC that was restored to operating condition by Carl Claunch, Mike Stewart, Ken Shiriff, and Marc Verdiell. Sotheby’s estimates the value at $200,000 to $300,000; in a world of billionaire megalomaniacs with dreams of space empires, we wouldn’t be surprised if a working AGC went for much, much more than that.

Meanwhile, current day space exploration is going swimmingly. Just this week NASA got the Hubble Space Telescope back online, which is great news for astronomers. And on Mars, the Ingenuity helicopter just keeps on delivering during its “operations demonstration” mission. Originally just supposed to be a technology demonstration, Ingenuity has proven to be a useful companion to the Perseverance rover, scouting out locations of interest to explore or areas of hazard to avoid. On the helicopter’s recent ninth flight, it scouted a dune field for the team, providing photographs that showed the area would be too dangerous for the rover to cross. The rover’s on-board navigation system isn’t great at seeing sand dunes, so Ingenuity’s images are a real boon to mission planners, not to mention geologists and astrobiologists, who are seeing promising areas of the ancient lakebed to explore.

And finally, most of us know all too well how audio feedback works, and all the occasions to avoid it. But what about video feedback? What happens when you point a camera that a screen displaying the image from the camera? Fractals are what happens, or at least something that looks a lot like fractals. Code Parade has been playing with what he calls “analog fractals”, which are generated just by video feedback and not by computational means. While he’d prefer to do this old school with analog video equipment, it easy enough to replicate on a computer; he even has a web page that lets you arrange a series of virtual monitors on your screen. Point a webcam at the screen, and you’re off on a fractal journey that constantly changes and shifts. Give it a try.