Articles by Al Williams

If you’ve ever owned a shortwave radio, you’ve probably listened at least a little to the BBC World Service. After all, they are a major broadcasting force, and with the British Empire or the Commonwealth spanning the globe, they probably had a transmitter close to your backyard. Recently, the BBC had a documentary about their early years of shortwave broadcasting. It is amazing both because it started so simply and when you think how far communications have progressed in just a scant 100 years.
Today, the BBC World Service broadcasts in over 40 languages distributing content via radio, TV, satellite, and the Internet. Hard to imagine it started with four people who were authorized to spend 10 pounds a week.

Early Days
The BBC started with radio 2LO broadcasting to London for a few hours each day in 1922. The service spread across the nation, and the publication of The Radio Times started in September 1923. Up until 1927, the BBC was the British Broadcasting Company, but in 1927 it became a corporation with a royal charter.
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As you can see, broadcasting has changed a little over the years. By 1932, the service built the famous Broadcasting House to become its new center of operations.
Shortwave
In 1932 it was pretty unusual to have an interest in worldwide broadcasting. But the Russians and the Vatican were using Shortwave to spread their ideology around the globe. The British, who at the time ruled 20% of the people on Earth, had a vested interest in bringing Britain to the four corners of the Empire. What better way than radio?
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As the director general said, “…don’t expect too much in the early days. The programmes with neither be very interesting nor very good.” That’s truth in advertising, but what did you expect on 10 pounds a week? However, not long after that, King George V addressed the world via radio to deliver a Christmas message. Many of the king’s subjects had never heard his voice before, and you can imagine this could help create a bond between people and monarch. The video below shows King Edward VIII’s first broadcast in 1936, about four years after King George’s
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Soon “London calling the British Empire” became a common thing to hear on the shortwave bands. The documentary explains the difficulty in building huge shortwave broadcasting sites around the world and then feeding programming to them via an underwater cable. Look at how a 700-foot radio tower went up in 1934.
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Arab Service and War
It wasn’t long after the BBC World Service formed that Hitler and Mussolini began using shortwave to push their ideas, too. In response to anti-British propaganda in Arabic, the Home Office asked the BBC to begin transmitting straight news to counter it, also in Arabic.
It wasn’t long before Prime Minister Nevel Chamberlain addressed the Empire about the threat of war via the BBC, and the remarks were translated into multiple languages. The World War brought the BBC’s international broadcasting to the forefront to keep the Empire informed and court favorable world opinion. It also became the home for broadcasts from occupied countries such as Greece and France.
The number of languages the BBC had to handle was staggering. Linguists, translators, and polyglots were in high demand for the service. Listening to the BBC was a crime in Nazi-occupied countries, but people did it anyway to get unbiased news and for a sense of hope. Of course, you can imagine that secret messages to spies and resistance cells were part of the broadcasts.
For example, Pierre Holmes hosted a 15-minute BBC program called “The French Speak to the French.” It often passed coded messages to the resistance regarding arms drops, missions, and even D-Day. For example, the D-Day invasion was signaled with a line from a poem: “Long violin sobs rock my heart in monotonous languish.”
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Not all the spies were good guys, though. The Germans planted a Dutch spy, posing as a refugee was picked up at sea. He repeatedly attempted to be allowed to read a message to his family over shortwave, but the message was really to his Nazi handlers. The British were too smart for this, however.
Speaking of spies, the BBC also monitored foreign radio broadcasts — sort of a precursor to GCHQ. You can see a portion of a newsreel about how the BBC recorded about 500,000 words a day during the war.
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Cold War
It wasn’t long after the World War that the Empire was transforming into the Commonwealth. But the world was also entering the so-called Cold War. Propaganda was tremendously important to the Cold War, and the BBC was one of the major voices of the West.
In addition to news, the BBC tried to highlight the differences between political ideals and everyday life behind the iron curtain using satire and intellectual programs. “The Two Comrades” program, for example, was a comedy about a party official in ridiculous situations. In one episode, there is a complaint that the party only received 99% of the vote, while in North Korea, they had managed 100% support for the party. Another program, “The Baffled Newspaper Reader,” would have one actor read text from an East German newspaper and another actor would provide the true and humorous meaning parenthetically.
There was also a program entitled “Letters without Signature,” which encouraged listeners to write about their life experiences. Since this often involved negative information, the listeners had to use spy-like methods to deliver their messages and not refer to things that might allow them to be identified by the secret police. The program’s introduction was something like this:
BBC – three dangerous letters. Dangerous for all those who fear the truth and especially  dangerous for all those who want to hear the truth and actually hear it at great personal risk.
Letters written to the BBC from target countries could be passed to MI6, facilitating messages from agents. Of course, inserting certain music or phrases into a broadcast also helped to communicate with spies in the field.
Scandal
One thing the BBC documentary doesn’t cover is the repeated scandals the BBC has faced over its life. Granted, most of those didn’t directly involve the World Service, but some peripherally did. For example, the BBC broadcast documentaries about Malaysia created by what amounted to a PR firm for Malaysia and eventually would apologize to its listeners around the world.
From the late 1930s until the end of the cold war, the BBC had an MI5 agent assigned who could bar subversives and suspected communists from being on the air or creating content. Once this was revealed, it generated a great deal of controversy. Jazz music, too, was banned for a while as a “filthy product of modernity.” Even Winston Churchill had been refused air time before World War II, something he remained angry about for years.
One scandal that directly hit the World Service was during the Falklands War. The BBC World Service was accused of broadcasting plans and positions of British military units.
On the other hand, you can’t make it to 90 without attracting some scandal. The BBC as a whole has had some doozies, but the World Service has usually avoided the focus of the big ones.
Digital Future
Like anything 90 years old, the BBC has transformed and changed. Today, you are as likely to listen to the BBC World Service using the Internet or satellite radio, and the BBC’s schedule reflects this. Radio broadcasts directed to developed nations are increasingly rare.
A few years ago, the BBC’s director general said that the BBC must prepare for a time when most of its audience never uses traditional broadcast channels. We are certain the BBC World Service will rise to the challenge.
We’ve looked at how the studios link to the transmitter sites. The BBC has had its share of odd stories over the years. […]

If you missed the Chumby, we’re sorry.  They were relatively inexpensive Linux appliances that acted as a clock, Internet radio, and feed reader. The company went belly up, although there was some functionality remaining thanks to one of the founders and now, for a subscription fee, you can still keep your Chumby operating. However, [Doug Brown] bought one with the goal of using it for his own applications. But the 2.6.28 kernel is showing its age. So he decided to push a new kernel on the device.
If you are a Chumby enthusiast, don’t get too excited. The goal isn’t to provide the existing Chumby apps with a new kernel, [Doug] says that’s probably impossible. Instead, he wants a modern booting infrastructure and kernel on the device for his own software.

The post is only part one, but it covers how he got U-Boot to load from an SD card. Given the success of that, we don’t think it will be long before the new kernel is running, too.
Understanding the boot process is a bit of arcane knowledge and [Doug] found back in 2013 that he didn’t quite understand it well enough to get the 3.13 kernel on the box, but now he’s ready to take the challenge and based on his work so far, we agree.
We were sad when Chumby stopped selling hardware. Chumby had white labeled the device to other companies, too, and we saw at least one of those driving a robot. […]

[Ben Conrad] received an interesting tool as a gift that purported to be a better mousetrap. It was a crescent wrench (made by the Crescent company, even) that didn’t have a tiny adjusting wheel like a traditional wrench. Instead, it had a slide running down the length of the handle. The idea is that you would push the slide to snug the wrench jaws against the bolt or nut, and that would be fast and easy compared to a conventional wrench. As [Ben] notes, though, it doesn’t work very well. Most of us would have just dumped it in the back of the tool chest or regifted it. [Ben] tore his apart to find out what was wrong with it.
A typical adjustable wrench has four parts. This one has 19 parts and looks like a conventional wrench with an extra slide and screw running down the length of the handle. [Ben] found the parts were poorly made, but that wasn’t the main problem.

While the poor machining caused skipping and jamming of the mechanism, he also found that even with perfect machining, the design was not very good. The jaws of the wrench move about an inch, and the slide moves about 2.5 inches. So that should offer some mechanical advantage, right? It turns out the screw is inefficient and eats up any potential force gain.
On the face of it, the wrench seems like a good idea exhibiting “out of the box” thinking. But the execution seems flawed. You have to wonder, though, how many basic tools could be improved if we would stop and think through without a lifetime of preconceptions.
We’ve pointed out before that if you build a better mousetrap, it had better be better. Then again, why adjust a wrench when you can make one the right size? […]

An accidental discovery by [3DQue] allows overhangs on FDM printers that seem impossible at first glance. The key is to build the overhang area with concentric arcs. It also helps to print at a cool temperature with plenty of fan and a slow print speed. In addition to the video from [3DQue], there’s also a video from [CNC Kitchen] below that covers the technique.
If you want a quick overview, you might want to start with the [CNC Kitchen] video first. The basic idea is that you build surfaces “in the air” by making small arcs that overlap and get further and further away from the main body of the part. Because the arcs overlap, they support the next arc. The results are spectacular. There’s a third video below that shows some recent updates to the tool.
We’ve seen a similar technique handcrafted with fullcontrol.xyz, but this is a Python script that semi-automatically generates the necessary arcs that overlap. We admit the surface looks a little odd but depending on why you need to print overhangs, this might be just the ticket. There can also be a bit of warping if features are on top of the overhang.
You don’t need any special hardware other than good cooling. Like [CNC Kitchen], we hope this gets picked up by mainstream slicers. It probably will never be a default setting, but it would be a nice option for parts that can benefit from the technique. Since the code is on GitHub, maybe people familiar with the mainstream slicers will jump in and help make the algorithm more widely available and automatic.
What will you build with this tool? If you don’t like arcs, check out conical slicing or non-planar slicing instead.

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[Asianometry] has been learning about gallium nitride semiconductors and shares what he knows in an informative video you can see below. This semiconductor material has a much higher bandgap voltage than the more common silicon. This makes it useful for applications that need higher efficiency and less heating.
The original use of the material was for LEDs, but we are seeing increasing use of the material in high-power applications like chargers. Phone chargers are especially common using this technology. This isn’t surprising when your think about how many phone chargers are needed worldwide every day.
Other places that need power-efficient devices are data centers, electric vehicles, and battery-operated equipment. It isn’t clear, though, that we can make enough of the material to meet global demand if it becomes extremely popular. This is especially true because the machinery and processes used to create silicon devices don’t work with gallium nitride. Silicon carbide is a competitor, and it could be easier to create, even though it isn’t as efficient as gallium nitride.
We’ve looked at gallium nitride before, and we are sure we are going to be seeing it again. Silicon carbide may one day operate on the surface of Venus. You can even use it to make homemade LEDs.
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Unless you are an audiophile, you likely think of tubes as mostly relegated to people who work on old technology. However, photomultiplier tubes are still useful compared to more modern sensors, and [Jaynes Network] has a look into how they work, especially with scintillating detectors.
The RCA photomultiplier he examines has ten stages and can detect even a single photon. Combined with a scintillating detector, they make good radiation detectors.
We can’t help but smile when we hear someone obviously in love with the engineering behind a tube like this. We get it. The inside of the tube is crowded, so it is hard to identify the dynodes and other portions, but some diagrams make it readily apparent how the tube does its job.
We were impressed with how good the documentation that came with the tube looked, considering its age. We mean the condition it was in. The document itself was obviously a reproduction of a typewritten document with hand-drawn figures and graphs.
We were hoping for some footage of the tube in action, but we’ll have to wait for a future video. We are betting that is coming, though. Although there are some solid-state detectors, they are not suitable for all applications. There was a time, though, when the tubes were in many applications, including X-ray scanners and photography equipment.

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[Smbakeryt] needs your help. He bought a 1984-vintage Z8000 coprocessor card for the PC, but the software is missing in action. Apparently, the co-processor — called a Trump Card — appeared in Byte magazine courtesy of the famous [Steve Ciarcia]. The schematics were published, and if you sent [Steve] proof that you built it, he’d send you the software. The product was later commercialized, but no one seems to have the software, so [Smbakeryt] is on the lookout for it.
The board itself was pretty amazing for its day. It added a 16-bit Zilog Z8000 CPU with 512 K of RAM. Big iron for 1984 and a good bit more performance than a stock IBM PC of the era.
We miss the days when computer gear came with big binders of documentation. These days, you are more likely to get a sticker with a URL. The Z8000 was a nice processor and could emulate the Z80, but it never became hugely popular. In addition to Zilog’s System 8000, the CPU found its way into some Unix computers including the Onyx C8002 and several Olivetti computers. Commodore planned to use the CPU in a canceled project. The Z8000 was famous for not using microcode and, thus, it fit on a relatively small die with 17,500 transistors (compared to the 8086’s 29,000 transistors).
We hope someone can help out with the software. If you want your own Z8000 system, you might be better off with Clover. Or, stick with a Z80 on the cheap.

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MIT has been working on very thin solar cells made of a film just a few microns thick. The problem? The cells are so thin that they’re hard to work with. You could make a small solar cell on top of, say, a glass slide, but that’s not all that interesting since you can make perfectly good solar cells that are as fragile as glass using conventional techniques. But in a new paper, MIT researchers describe creating 50-micron-thin fabrics that can generate electricity from solar.
The process still involves using chemical vapor deposition to produce the solar cell on glass. However, the cells are removed from the glass, prepared with electrodes, and then transferred to a piece of fabric which acts as a new substrate.
The fabric used in the paper is a composite fabric known as Dyneema composite fabric. It uses ultra-high molecular weight polyethylene fibers and sheets of Mylar. This material has low weight but a very high strength. A UV cure adhesive bonds the fabric and solar cells.
Honestly, we doubt anyone will be making these in their garages anytime soon. But we would love to see what you could do with a roll of this fabric. Wearables, self-charging laptop bags, or solar-powered instruments in an airborne drone could all take advantage of the material’s flexibility and low weight. […]

What do you get if you cross graphene, hexagonal boron nitride, and tungsten diselenide? Well, according to researchers at Hunan University, you get a field effect transistor that can act as both a switching element or a memory cell. The partial floating-gate field-effect transistor or PFGFET uses 2D van der Walls heterostructures to deal with isolated atomic layers. The paper in Nature is unfortunately behind a pay wall, but you can read a summary over on [TechExplore].
The graphene acts as the gate, and the transistor can be switched between n-type behavior and p-type behavior. It can also be configured as a switching element or as a memory element similar to an EEPROM cell.
One advantage of having configurable transistor types is that a single transistor structure can produce CMOS or complementary circuits. Traditionally, a CMOS IC has two different transistor structures and often producing one of them requires extra effort.
The configuration takes place by applying a control voltage pulse. A negative control voltage produces a p-type FET and a positive voltage configures the same transistor as an n-type. If you don’t have access to the paper, the figures available online offer a good bit of insight into the device’s design.
If you want to learn more about ordinary MOSFETs, we talk about them often. You can also get the skinny on CMOS from [Bil Herd]. […]

Robot “dogs” are all the rage lately, but you probably haven’t seen one that can climb up a wall. Researchers in Korea have made one that can, assuming the wall is made out of a metal that a magnet can stick to at least. The robot, MARVEL or magnetically adhesive robot for versatile and expeditious locomotion, might be pressing its luck on acronyms, but it is pretty agile as you can see in the video below. Tests showed the robot walking on walls and ceilings. It can cross gaps and obstacles and can even handle a curved storage tank with paint and rust.
The robot weighs 8 kilograms (17.6 pounds), can carry 2 – 3 kg of payload, and operates without a tether. Each foot contains both an electropermanent magnet and magnetorheological elastomers. If you haven’t seen them before, an electropermanent magnet, or EPM, is a magnet that can be turned on or off electronically. The elastomer is a polymer containing ferromagnetic particles that can alter the material’s properties in response to a magnetic field.
EPMs have two parts. One part is a simple permanent magnet. The other is a soft core easily magnetized by a surrounding coil. If you magnetize the soft core to oppose the permanent magnet, the fields cancel out, effectively turning off the magnet. If you magnetize it the other way, it reinforces the field.
This is better than an electromagnet in this application because turning the magnet on or off only requires a brief pulse. If you want your robot to hang out on the ceiling with Spider Man indefinitely, you don’t have to worry about draining your batteries while keeping an electromagnet engaged.
Overall, an interesting robot. Most wall-climbing robots we’ve seen are pretty lightweight. We don’t see nearly as many that can have the feeling of clinging to the ceiling.

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