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Join [Jørgen Kragh Jakobsen], Analog/digital Design Engineer at Merus-Audio, for this week’s Hack Chat.
Every week, we find a few interesting people making the things that make the things that make all the things, sit them down in front of a computer, and get them to spill the beans on how modern manufacturing and technology actually happens. This is the Hack Chat, and it’s happening this Friday, March 31, at noon PDT (20:00 UTC).
Jørgen’s company has developed a line of multi level Class D amplifiers that focus on power reduction to save battery life in mobile application without losing audio quality.
There are a lot of tricks to bring down power consumption, some on core technologies on transistor switching, others based on input level where modulation type and frequency is dynamically changed to fit everything from background audio level to party mode.
Here’s How To Take Part:
Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.
Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.
You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.
Upcoming Hack Chats
We’ve got a lot on the table when it comes to our Hack Chats. On April 7th, our host will be [Samy Kamkar], hacker extraordinaire, to talk reverse engineering.
In the last edition of Don’t Fear the Filter, we built up two examples of the simplest and most-used active filter of all time: the two-pole Sallen-Key lowpass. This time, we’re going to put two of these basic filter blocks in a row, and end up with a much sharper lowpass filter as well as a bandpass filter. For the bandpass, we’ll need to build up a quick highpass filter as well. Bonus!
I claimed last time that the Sallen-Key lowpass would cover something like 80% of your filtering needs. (And 72.4% of all statistics are totally made up!) These two will probably get you through another 10% or so. Honestly, I’ve never built a standalone active highpass, for reasons we’ll see below, but the active bandpass filter that we’re building it for is a great tool to have in your belt, especially for anything audio.
The 20th century saw some amazing technological developments. We went from airplanes to the moon. We went from slide rules to digital computers. Crank telephones to cell phones. But two of the most amazing feats of that era were ones that non-technical people probably hardly think about. The transformation of radio and TV from mono and black and white, to stereo and color. What was interesting about both of these is that engineers managed to find a way to push the new better result into the same form as the old version and — this is the amazing part — do it in such a way that the old technology still worked. Maybe it is the rate that new technology moves today, but we aren’t doing that today. Digital TV required all-new everything: transmitters, receivers, frequencies, and recording gear. Good luck trying to play the latest video game on your 25-year-old PC.
It is hard to remember when stores were full of all sorts of audio and video media. We’ve noticed that all forms of media are starting to vanish. Everything audio and video are all streamed or downloaded these days. Records, 8-tracks, cassettes, and even CDs and DVDs are vanishing. However, vinyl records have made a come back in the last few years for their novelty or nostalgic value.
The VCF East is the largest gathering of retrocomputing aficionados on the east coast. It’s three days of talks, exhibits, a flea market, and a pow-wow of the greatest minds buried under obsolete technology. No VCF is complete without a few talks, and this year is shaping up to be great. Keynotes will include [Bjarne Stroustrup], designer / implementor / inventor of C++. Computer historian [Bill Degnan] will give a review of 40 years of ‘appliance computers’, and [Tom Perera], Ph.D. will be giving a talk on the Enigma machine.
The exhibits at VCF are always the star of the show, and this year is no different. Highlights include mechanical computers, the finest from Silicon Graphics, and a version of Unix published by Microsoft. The individual exhibits are always great; last year the world’s first digital camera made an appearance. If you’re in the area, this isn’t an event to miss. VCF is going down at InfoAge, a science center at the former Camp Evans — a military installation that is best described as, ‘DARPA before World War II’.
Hackaday is proud to once again sponsor VCF East. This has been going on for a couple of years now and our Art Director, [Joe Kim] has created some incredible art as part of the sponsorship. Click on the thumbnail of this year’s art to embiggen. The VCF West art from last year is a stunning take on the Macintosh and last year’s VCF East art reflected the retro hackathon we sponsored.
The nuclear age changed steel, and for decades we had to pay the price for it. The first tests of the atomic bomb were a milestone in many ways, and have left a mark in history and in the surface of the Earth. The level of background radiation in the air increased, and this had an effect on the production of steel, so that steel produced since 1945 has had elevated levels of radioactivity. This can be a problem for sensitive instruments, so there was a demand for steel called low background steel, which was made before the trinity tests.
The Bessemer process pumps air through the iron to remove impurities. shropshirehistory.com
The production of steel is done with the Bessemer process, which takes the molten pig iron and blasts air through it. By pumping air through the steel, the oxygen reacts with impurities and oxidizes, and the impurities are drawn out either as gas or slag, which is then skimmed off. The problem is that the atmospheric air has radioactive impurities of its own, which are deposited into the steel, yielding a slightly radioactive material. Since the late 1960s steel production uses a slightly modified technique called the BOS, or Basic Oxygen Steelmaking, in which pure oxygen is pumped through the iron. This is better, but radioactive material can still slip through. In particular, we’re interested in cobalt, which dissolves very easily in steel, so it isn’t as affected by the Bessemer or BOS methods. Sometimes cobalt is intentionally added to steel, though not the radioactive isotope, and only for very specialized purposes.
Recycling is another reason that modern steel stays radioactive. We’ve been great about recycling steel, but the downside is that some of those impurities stick around.
Why Do We Need Low Background Steel?
Imagine you have a sensor that needs to be extremely sensitive to low levels of radiation. This could be Geiger counters, medical devices, or vehicles destined for space exploration. If they have a container that is slightly radioactive it creates an unacceptable noise floor. That’s where Low Background Steel comes in.
A person is placed into a low background steel container with sensitive equipment to measure the radioactivity of the body, which may be near the background level. Photo from orau.org
So where do you get steel, which is a man-made material, that was made before 1945? Primarily from the ocean, in sunken ships from WWII. They weren’t exposed to the atomic age air when they were made, and haven’t been recycled and mixed with newer radioactive steel. We literally cut the ships apart underwater, scrape off the barnacles, and reuse the steel.
Fortunately, this is a problem that’s going away on its own, so the headline is really only appropriate as a great reference to a popular movie. After 1975, testing moved underground, reducing, but not eliminating, the amount of radiation pumped into the air. Since various treaties ending the testing of nuclear weapons, and thanks to the short half-life of some of the radioactive isotopes, the background radiation in the air has been decreasing. Cobalt-60 has a half-life of 5.26 years, which means that steel is getting less and less radioactive on its own (Cobalt-60 from 1945 would now be at .008% of original levels). The newer BOS technique exposes the steel to fewer impurities from the air, too. Eventually the need for special low background steel will be just a memory.
Oddly enough, steel isn’t the only thing that we’ve dragged from the bottom of the ocean. Ancient Roman lead has also had a part in modern sensing.
PoC||GTFO 14 is now out. It’s a 40 MB PDF that’s also a Nintendo Entertainment System ROM, and a Zip archive. Pastor Laphroaig Screams High Five To The Heavens As The Whole World Goes Under. Download this, but don’t link – host it yourself. Bitrot will be the end of us all.
[Photonicinduction] is back. The guy best known for not starting an electrical fire in his attic has been working through some stuff recently. He got married, went to India, and he’s going to try to blow a five thousand amp fuse. Good on him.
There’s a certain segment of the Internet that believes the Raspberry Pi Zero doesn’t exist. The logic goes something like this: because I can’t buy a Ferrari right now, Ferraris don’t exist. Now there’s a new and improved website that checks if the Pi Zero and Pi Zero W are in stock: thepilocator.com. It checks a dozen or so online stores for the Pi Zero and Pi Zero W. Guess what? They’re mostly in stock.
[bxcounter] built a PC case and holy crapthis thing is incredible. This case is made out of Paulownia wood, and is made up out of fifty pieces held together with magnets. This thing is hand-carved and looks fantastic. Inside is a Mini-ITX motherboard, an i3, a Gigabyte ITX-sized 1060, and an SSD. It’s no powerhouse, but then again it’s not overkill, either. This is a fantastic addition to any battlestation.
As most hackerspaces do, the Omaha Maker Group had a storage problem. Previously, members used plastic totes someone picked up as surplus, but these totes were in short supply. Banker’s Boxes are a better idea, but how to store them? A box case. This ‘bookcase for boxes’ holds 21 standard Banker’s Boxes and only uses two full sheets of MDF in its construction.
It is widely accepted that Gutenberg’s printing press revolutionized thought in Europe and transformed the Western world. Prior to the printing press, books were rare and expensive and not generally accessible. Printing made all types of written material inexpensive and plentiful. You may not think about it, but printing–or, at least, printing-like processes–revolutionized electronics just as much.
In particular, the way electronics are built and the components we use have changed a lot since the early 1900s when the vacuum tube made amplification possible. Of course, the components themselves are different. Outside of some specialty and enthusiast items, we don’t use many tubes anymore. But even more dramatic has been how we build and package devices. Just like books, the key to lowering cost and raising availability is mass production. But mass producing electronic devices wasn’t always as easy as it is today.
Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.
Fortunately, this is a problem that’s going away on its own, so the headline is really only appropriate as a great reference to a 
