Hackaday Links: November 12, 2023

November 12, 2023 by Dan Maloney 11 Comments

Somebody must really have it in for Cruise, because the bad press just keeps piling up for the robo-taxi company. We’ve highlighted many of the company’s woes in this space, from unscheduled rendezvous with various vehicles to random acts of vandalism and stupid AI pranks. The hits kept coming as California regulators pulled the plug on testing, which finally convinced parent company General Motors to put a halt to the whole Cruise testing program nationwide. You’d think that would be enough, but no — now we learn that Cruise cars had a problem recognizing children, to the point that there was concern that one of their autonomous cars could clobber a kid under the right conditions. The fact that they apparently knew this and kept sending cars out for IRL testing is a pretty bad look, to say the least. Sadly but predictably, Cruise has announced layoffs, starting with the employees who supported the now-mothballed robo-taxi fleet, including those who had the unenviable job of cleaning the cars after, err, being enjoyed by customers. It seems a bit wrongheaded to sack people who had no hand in engineering the cars, but then again, there seems to be a lot of wrongheadedness to go around.

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Leaky SMD Electrolytics? Try These Brute Force Removal Methods

November 12, 2023 by Dan Maloney 25 Comments

When you say “recapping” it conjures up an image of a dusty old chassis with point-to-point wiring with a bunch of dried-out old capacitors or dodgy-looking electrolytics that need replacement. But time marches on, and we’re now at the point where recapping just might mean removing SMD electrolytics from a densely packed PCB. What do you do then?

[This Does Not Compute]’s answer to that question is to try a bunch of different techniques and see what works best, and the results may surprise you. Removal of SMD electrolytic caps can be challenging; the big aluminum can sucks a lot of heat away, the leads are usually pretty far apart and partially obscured by the plastic base, and they’re usually stuffed in with a lot of other components, most of which you don’t want to bother. [TDNC] previously used a hot-air rework station and liberally applied Kapton tape and aluminum foil to direct the heat, but that’s tedious and time-consuming. Plus, electrolytics sometimes swell up when heated, expelling their corrosive contents on the PCB in the process.

As brutish as it sounds, the solution might just be as simple as ripping caps off with pliers. This seems extreme, and with agree that the risk of tearing off the pads is pretty high. But then again, both methods seemed to work pretty well, and on multiple boards too. There’s a catch, though — the pliers method works best on caps that have already leaked enough of their electrolyte to weaken the solder joints. Twisting healthier caps off a PCB is likely to end in misery. That’s where brutal method number two comes in: hacking the can off the base with a pair of flush cutters. Once the bulk of the cap is gone, getting the leads off the pad is a simple desoldering job; just don’t forget to clean any released schmoo off the board — and your cutters!

To be fair, [This Does Not Compute] never seems to have really warmed up to destructive removal, so he invested in a pair of hot tweezers for the job, which works really well. But perhaps you’re not sure that you should just reflexively replace old electrolytics on sight. If so, you’re in pretty good company.

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Neopixels? Try Liquid Nitrogen To Color Shift Your LEDs Instead

November 11, 2023 by Dan Maloney 23 Comments

If you’re like us, you’ve never spent a second thinking about what happens when you dunk an ordinary LED into liquid nitrogen. That’s too bad because as it turns out, the results are pretty interesting and actually give us a little bit of a look at the quantum world.

The LED fun that [Sebastian] over at Baltic Lab demonstrates in the video below starts with a bright yellow LED and a beaker full of liquid nitrogen. Lowering the powered LED into the nitrogen changes the color of the light from yellow to green, an effect that reverses as the LED is withdrawn and starts to warm up again. There’s no apparent damage to the LED either, although we suppose that repeated thermal cycles might be detrimental at some point. The color change is quite rapid, and seems to also result in a general increase in the LED’s intensity, although that could be an optical illusion; our eyes are most sensitive in the greenish wavelengths, after all.

So why does this happen? [Sebastian] goes into some detail about that, and this is where quantum physics comes into it. The color of an LED is a property of the bandgap of the semiconductor material. Bandgap is just the difference in energy between electrons in the valence band (the energy levels electrons end up at when excited) and the conduction band (the energy levels they start at.) There’s no bandgap in conductive materials — the two bands overlap — while insulators have a huge bandgap and semiconductors have a narrow gap. Bandgap is also dependent on temperature; it increases with decreasing temperature, with different amounts for different semiconductors, but not observably so over normal temperature ranges. But liquid nitrogen is cold enough for the shift to be dramatically visible.

We’d love to see the color shift associated with other cryogens, or see what happens with a blue LED. Want to try this but don’t have any liquid nitrogen? Make some yourself!

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Solder Two Boards At Once With This Dual Reflow Plate

November 10, 2023 by Dan Maloney 4 Comments

Homebrew reflow projects generally follow a pretty simple formula: find a thrift shop toaster oven or hot plate, add a microcontroller and a means to turn the heating element on and off, and close the loop with a thermistor. Add a little code and you’re melting solder paste. Sometimes, though, a ground-up design works better, like this scalable reflow plate with all the bells and whistles.

Now, we don’t mean to hate on the many great reflow projects we’ve seen, of course. But [Michael Benn]’s build is pretty slick. The business end uses 400-watt positive temperature coefficient (PTC) heating elements from Amazon controlled by solid-state relays, although we have to note that we couldn’t find the equivalent parts on the Amazon US site, so that might be a problem. [Michael] also included mechanical temperature cutoffs for each plate, an essential safety feature in case of thermal runaway. The plates are mounted at the top of a 3D-printed case, which also has an angled enclosure for a two-color OLED display and a rotary encoder.

The software runs on an ESP32 and supports multiple temperature profiles for different solder pastes. The software also supports different profiles on the two plates, and even allows for physical expansion to a maximum of four heating plates, or even just a single plate if that’s what you need. The video below shows it going through its paces along with the final results. There’s also a video showing the internals if that’s more your style

We appreciate the fit and finish here, as well as the attention to safety. Can’t find those heating elements for your build? You might have to lose your appetite for waffles.

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Hands On With Boondock Echo

November 10, 2023 by Dan Maloney 23 Comments

Perhaps no words fill me with more dread than, “I hear there’s something going around.” In my experience, you hear this when some nasty bug has worked its way into the community and people start getting whatever it is. I’m always on my guard when I hear about something like this, especially when it’s something really unpleasant like norovirus. Forewarned is forearmed, after all.

Since I work from home and rarely get out, one of the principal ways I keep apprised of what’s going on with public health in my community is by listening to my scanner radio. I have the local fire rescue frequencies programmed in, and if “there’s something going around,” I usually find out about it there first; after a half-dozen or so calls for people complaining of nausea and vomiting, you get the idea it’s best to hunker down for a while.

I manage to stay reasonably well-informed in this way, but it’s not like I can listen to my scanner every minute of the day. That’s why I was really excited when my friend Mark Hughes started a project he called Boondock Echo, which aims to change the two-way radio communications user experience by enabling internet-backed recording and playback. It sounded like the perfect system for me — something that would let my scanner work for me, instead of the other way around. And so when Mark asked me to participate in the beta test, I jumped at the chance.

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Cheap Power Supplies With Fake Chips Might Not Be That Bad

November 10, 2023 by Dan Maloney 33 Comments

We all know the old maxim: if it’s too good to be true, it’s probably made with fake components. OK, maybe that’s not exactly how it goes, but in our world gone a little crazy, there’s good reason to be skeptical of pretty much everything you buy. And when you pay the equivalent of less than a buck for a DC-DC converter, you get what you pay for.

Or do you? It’s not so clear after watching [Denki Otaku]’s video on a bargain bag of buck converters he got from Amazon — ¥1,290 for a lot of ten, or $0.85 a piece. The thing that got [Denki]’s Spidey senses tingling is the chip around which these boards were built: the LM2596. These aren’t especially cheap chips; Mouser lists them for about $5.00 each in a reel of 500.

Initial testing showed the converters, which are rated at 3 to 42 VDC in and 1.25 to 35 VDC out, actually seem to do a decent job. At least with output voltage, which stays at the set point over a wide range of input voltages. The ripple voltage, though, is an astonishing 400 mV — almost 10% of the desired 5.0 V output. What’s more, the ripple frequency is 18 kHz, which is far below the 150 kHz oscillator that’s supposed to be in the LM2596. Other modules from the batch tested at 53 kHz ripple, so better, but still not good. There were more telltales of chip fakery, such as dodgy-looking lettering on the package, incorrect lead forming, and finger-scorching heat under the rated 3 A maximum load. Counterfeit? Almost definitely. Useless? Surprisingly, probably not. Depending on your application, these might do the job just fine, especially if you slap a bigger cap on the output to smooth that ripple and keep the draw low. And keep your fingers away, of course.

Worried that your chips are counterfeits? Here’s a field guide for fake chip spotters. And what do you do if you get something fake? A refund might just be possible.

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Does Getting Into Your Garage Really Need To Be Difficult?

November 9, 2023 by Dan Maloney 78 Comments

Probably the last thing anyone wants when coming home from a long day at work or a trip is to be hassled at the last possible moment — gaining entrance to your house. But for some home automation enthusiasts, that’s just what happened when they suddenly learned that their own garage doors had betrayed them.

The story basically boils down to this: Chamberlain, a US company that commands 60% of the garage door market, recently decided to prevent “unauthorized usage” of their MyQ ecosystem through third-party apps. Once Chamberlain rolled out the change, users of Home Assistant and other unauthorized apps found themselves unable to open or close their doors with the apps they were accustomed to.

Those of us with custom smart home setups can relate to how frustrating it is when something disturbs the systems you’ve spent a lot of time tweaking and optimizing. It’s especially upsetting for users who both Chamberlain hardware specifically because it was supported by Home Assistant, only to have the company decide to drop support. This feels like false advertising, but we strongly suspect that buried in the EULA users must have agreed to at some point is a clause that essentially says, “We can do anything we want and tough noogies to you.” And if you read through the article linked above, you’ll get an idea why Chamberlain did this — they probably didn’t like the idea that users were avoiding their ad-spangled MyQ app for third-party interfaces, depriving them of ad revenue and the opportunity for up-selling.

We feel the frustration of these users, but rather than curse the darkness, perhaps this will light a candle of righteous rage that leads to a clever workaround. The Home Assistant blog article mentions a dongle called ratgdo, which should allow any door with plain old dry contacts to work via MQTT or ESPHome. It’s extra work that users shouldn’t have to put in, but maybe getting one over on The Man would be worth the effort.

Thanks to [KC] for the tip; please keep us posted on your workaround.