Author: Maya Posch

1889 Articles

Grid Batteries On Wheels: The Complicated Logistics Of Vehicle-Grid Integration

March 8, 2022 by 93 Comments

At its core, the concept of vehicle-grid integration (VGI) – also called Vehicle To Grid (V2G) – seems a simple one. Instead of a unidirectional charger for battery-electric vehicles (BEVs), a bidirectional charger would be used. This way, whenever the BEV is connected to such a charger, power could be withdrawn from the car’s battery for use on the local electrical grid whenever there’s demand.

Many of the complications with VGI have already been discussed, including the increased wear that this puts on a BEV’s battery, the need for an inherently mobile machine to be plugged into a charger, and the risk of needing one’s BEV and finding its battery to be nearly depleted. Here the cheerful marketing from Nissan and that from commercial initiatives such as Vehicle to Grid Britain makes it sound like it’s a no-brainer once those pesky details can be worked out.

In parallel with the world of glossy marketing leaflets, researchers have been investigating VGI as a potential option for grid-level energy storage. These studies produce a far less optimistic picture that puts the entire concept of VGI into question.

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Greedy Receivers: FCC Considers Regulating Receivers After Altimeter Showdown

March 7, 2022 by 94 Comments

Recently, the media was filled with articles about how turning on 5G transmissions in the C-band could make US planes fall out of the sky. While the matter was ultimately resolved without too much fuss, this conflict may have some long-term consequences, with the FCC looking to potentially address and regulate the root of the problem, as reported by Ars Technica.

At the heart of the whole issue is that while transmitters are regulated in terms of their power and which part of the spectrum they broadcast on, receivers are much less regulated. This means that in the case of the altimeters in airplanes for example, which use the 4.2 GHz – 4.4 GHz spectrum, some of their receivers may be sensitive to a part of the 5G C-band (3.7 GHz -3.98 GHz), despite the standard 200 MHz guard band (upped to 400 MHz in the US) between said C-band and the spectrum used by altimeters.

What the FCC is currently doing is to solicit ways in which it could regulate the performance and standards for receivers. This would then presumably not just pertain to 5G and altimeters, but also to other receivers outside of avionics. Since the FCC already did something similar back in 2003 with an inquiry, but closed it back in 2007 without any action taken, it remains to be seen whether this time will be different. One solid reason would be the wasted spectrum: a 400 MHz guard band is a very large chunk.

Thanks to [Chris Muncy] for the tip.

The AUO-manufactured controller board of an LG-branded TV. (Credit: Andrew Menadue)

What To Do With A Broken Television When You Can’t Fix It

February 22, 2022 by 31 Comments

Who can say ‘no’ to a free TV, even if it’s broken? This was the situation [Andrew Menadue] ended up in last year when he was offered an LG 39LE4900 LCD TV. As [Andrew] describes in the blog post along with videos (see first part embedded after the break), this particular television had been taken to a television repair shop previously after the HDMI inputs stopped working, but due to a lack of replacement parts the owner had to make due with the analog inputs still working. That is, until those stopped working as well.

The nice thing about these TVs is that they are very modular inside, as [Andrew] also discovered to his delight. In addition to the LG controller board, an inverter board and the power supply board, this TV also contained a TCON PCB. After some initial unsuccessful swapping of the parts with EBay replacements, nothing was (surprisingly) working, but it did turn out that the TCON and inverter boards are made and sold by AUO (major Taiwanese display manufacturer), along with the display itself.

In the end it turned out that the AUO boards and screen were fine, and after sourcing a board to convert VGA input to the LVDS signal accepted by the TCON board, the whole display worked. Naturally using a board with HDMI inputs would be nice, but it does show how a ‘broken’ TV can be turned into a really nice, big monitor without all too much effort if it’s just the controller board that went on the fritz.

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Ray Tracing On A Modern TI Graphing Calculator

February 21, 2022 by 16 Comments

Something being impractical isn’t any reason not to do it, which is why just about anything with a CPU in it can run Doom by now. For the same reason there obviously is a way to do ray tracing of 3D scenes on a modern-day TI-84 Plus CE graphical calculator. This is excellent news for anyone who has one of these calculators, along with a lot of time, perhaps during boring classes, to spare.

As [TheScienceElf] demonstrates in a video, also embedded after the break, it’s not quite the real-time experience one would expect from an NVidia RTX 30-series GPU. Although the eZ80-based CPU in the calculator is significantly more efficient than a Z80 as found in many 1980s home computers, the demo scene at standard resolution takes about 12 minutes to render, as also noted on the GitHub project page.

Perhaps the most interesting part about this project is its use of the Clang-based C & C++ toolchain for the TI-84 Plus CE which gives easy access to the calculator’s hardware and related, including graphics, file I/O, fonts, keypad input and more. Even if using a TI-84 Plus CE to render the next Pixar-level movie isn’t the most productive use imaginable for these devices, this project and the CE toolchain make it all too easy to tinker with these $150 devices.

It would also offer a nice change of pace from writing Snake in TiBASIC, a BASIC dialect in which [TheScienceElf] incidentally has also written a ray tracer.

(Thanks to [poiuyt] for the tip)

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Pre-exploded PSU close-up: shown is inductor with the heatsink it shorted against.

The Little Replacement PSU That Could: Kill A Microsoft Surface And Monitor

February 21, 2022 by 55 Comments

Recently [Big Clive], everyone’s favorite purveyor of anything electronic that’s dodgy, cheap, cheerful, decidedly crispy or any combination thereof, got sent a very dead external power supply unit. Being clearly a third-party PSU with poorly written and many (likely not truthful) safety approval markings on its label, this PSU had the dubious honor of having destroyed a Microsoft Surface computer as well as the monitor that was connected at the time.

In [Clive]’s video (also embedded after the break) the black and very crispy board is examined, showing a wealth of vaporized traces and plenty of soot. What’s however most fascinating is the failure mode: instead of something obvious like e.g. the main transformer between the primary and secondary side failing, here it would seem that an inductor (see heading image) on the secondary side had its insulation rubbed off and shorted on a nearby heatsink. A heatsink that just happened to be also electrically connected on the primary (mains-level) side.

Judging by the former owner’s report and aftermath, this led to a very sudden and violent demise of the PSU, with mains power very likely making its way into the unsuspecting Surface system and connected monitor. The number of ‘very nope’ design decisions made in this PSU are astounding, and a lesson for both aspiring EEs and anyone considering getting a ‘cheap’ third-party replacement PSU.

(Thanks to [Helge] for the tip)

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The Electrifying Debate Around Where Lightning Comes From

February 17, 2022 by 26 Comments

Along with many other natural phenomena, lightning is probably familiar to most. Between its intense noise and visuals, there is also very little disagreement that getting hit by a lightning strike is a bad thing, regardless of whether you’re a fleshy human, moisture-filled plant, or conductive machine. So it’s more than a little bit strange that the underlying cause of lightning, and what makes certain clouds produce these intense voltages along ionized air molecules, is still an open scientific question.

Many of us have probably learned at some point the most popular theory about how lightning forms, namely that lightning is caused by ice particles in clouds. These ice particles interact to build up a charge, much like in a capacitor. The only issue with this theory is that this process alone will not build up a potential large enough to ionize the air between said clouds and the ground and cause the lightning strike, leaving this theory in tatters.

A recent study, using data from Earth-based radio telescopes, may now have provided fascinating details on lightning formation, and how the charge may build up sufficiently to make us Earth-based critters scurry away to safety when dark clouds draw near.

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Crimping Tools And The Cost Of Being Cheap

February 7, 2022 by 113 Comments

Crimp connectors provide an easy and convenient way to connect electronics while still allowing for them to be removed and swapped without having to reach for a soldering iron and desoldering wick. While browsing one’s favorite cheap shopping site, you may get the impression that all one has to do to join the world of crimp-awesome is order a $20 crimp tool and some assorted ‘JST’ and ‘DuPont’ (a Mini-PV clone) connectors to go with it. After all, it’s just a bit of metal that’s squeezed around some stripped wire. How complicated could this be?

The harsh truth is that, as ridiculous as the price tag on official JST and Mini-PV crimping tools may seem at hundreds of dollars each, they offer precise, repeatable crimps and reliable long-term stability. The same is true for genuine JST, Mini-PV and Molex connectors. The price tag for ‘saving a buck’ may end up being a lot higher than the money originally saved.

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