Author: Al Williams

4504 Articles

Satellite Ground Station Upcycles Trash

April 3, 2021 by 30 Comments

While the term “upcycle” is relatively recent, we feel like [saveitforparts] has been doing it for a long time. He’d previously built gear to pick up low-Earth orbit satellites, but now wants to pick up geosynchronous birds which requires a better antenna. While his setup won’t win a beauty contest, it does seem to work, and saved some trash from a landfill, too. (Video, embedded below.)

Small dishes are cheap on the surplus market. A can makes a nice feedhorn using a classic cantenna design, although that required aluminum tape since the only can in the trash was a cardboard oatmeal carton. The tape came in handy when the dish turned out to be about 25% too small, as well.

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One Bit CPU Runs At A Blistering 60Hz

March 31, 2021 by 20 Comments

If you really think hard about it, a CPU is just a very general-purpose state machine. Well, most CPUs are, anyway. The MC14500 is a one-bit computer that has only 16 instructions and was meant to serve in simple tasks where a big CPU wouldn’t work for space, power, or budget reasons. However, [Laughton] took the idea one step further and created a single-bit computer with no real instructions to control a printing press. The finished machine uses a clever format in an EEPROM to drive an endless program.

Honestly, we’d say this is more of a state machine, but we like the idea of it being a minimal CPU which is also true. The design uses the EEPROM in an odd way. Each CPU address really addresses a block of four bytes. The byte that gets processed depends on the current phase and the status of the one-bit flag register.

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Moving Things With Electricity

March 29, 2021 by 9 Comments

We use electricity to move things with the help of motors and magnets all the time. But if you have enough voltage, you can move things with voltage alone. As [James] found out, though, it works best if your objects — ping pong balls, in his case — are conductive.

He wanted to add a Van de Graaff generator to add to his “great ball machine” which already has some cool ways to move ping pong balls. However, to get the electrostatic motion, [James] had to resort to spraying the balls with RF shielding spray.

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Code Talkers: Programming With Voice

March 28, 2021 by 18 Comments

IEEE Spectrum had an interesting post covering several companies trying to sell voice programming interfaces. Not programming APIs for speech recognition, but the replacement of the traditional text editor to produce programs.

The companies, Serenade and Talon, have very different styles. Serenade has fairly normal-sounding language, whereas Talon has you use very specific phrases and can even use eye tracking to figure out what you are looking at when you issue a command. There’s also mention of two open-source products (Aenae and Caster) that require you to use a third-party speech engine.

For an example of Talon’s input, imagine you want this line of code in your program:

name=extract_word(m)

You’d say this out loud: “Phrase name op equals snake extract word paren mad.” Not exactly how Star Trek envisioned voice programming.

For accessibility, this might be workable. It is hard for us to imagine a room full of developers all talking to make their computers enter C or Python code. Until we can say, “Computer, build a graphic using the data in file hackaday-27,” we think this is not going to go mainstream.

The actual speech recognition part is pretty much a commodity now. Making a reasonable set of guesses about what people will say and what they mean by it is something else. It seems like this works best when you have a very specific and limited vocabulary, like operating a 3D printer.

Image Sensors Demystified By [IMSAI Guy]

March 27, 2021 by 2 Comments

The February 1975 issue of Popular Electronics had what was — at the time — an amazing project. The Cyclops, a digital camera with a 32 by 32 pixel resolution with 4 bits per pixel. It was hard to imagine then that we would now all carry around high-resolution color cameras that were also phones, network terminals, and so many other things. But how much do you know about how those cameras really work? If you want to know more, check out [IMSAI Guy’s] recent video on how image sensors work.

The video doesn’t cover any practical projects or circuits, but it has a good explanation of what goes on in modern digital cameras. If you don’t know what digital cameras have in common with an octopus, you might want to watch.

If you want to see what the state of the art in 1975 was, have a look at this post. The image sensor in that camera didn’t have much in common with the ones we use today, but you have to admit it is clever. Of course, 1975 was also the year Kodak developed a digital camera and failed to understand what to do with it. Like the Cyclops, it had little in common with our modern smartphone cameras, but you have to start somewhere.

Raspberry Pi Zero Beams Back Video From 100,000 Feet

March 26, 2021 by 13 Comments

The Project Horus team routinely launches high-altitude balloons in Australia. However, despite their desire for it, they haven’t beamed back live video. Until now. Horus 55 beamed video back to the ground from over 100,000 feet using a Raspberry Pi and some software-defined radio gear. Be sure and check out their video, below.

You might think this is easy, but there are many technical hurdles. First, the transmitter needs some power, but the thin atmosphere creates problems with cooling. In addition a really good receiving station is required, and the project wanted to stream that video to the Internet, which they were able to do.

The balloon carried a Raspberry Pi Zero W to capture and compress video. A LimeSDR Mini provided the DVB-S transmission on 70cm along with a power amplifier to get to about 800mW. Power dissipation in the payload was about 6 watts and required a special heat sink system to operate. The payload was powered by eight lithium AA primary cells, which perform well at low temperatures.

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Move Over Cesium Clock, Optical Clocks Are Taking Over

March 26, 2021 by 26 Comments

We normally think of atomic clocks as the gold standard in timekeeping. The very definition of a second — in modern times, at least — is 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of a stationary cesium-133 atom at a temperature of 0K. But there is a move to replace that definition using optical clocks that are 100 times more accurate than a standard atomic clock.

In recent news, the Boulder Atomic Clock Optical Network — otherwise known as BACON — compared times from three optical clocks and found that the times differed a little more than they had predicted, but the clocks were still amazingly accurate relative to each other. Some of the links used optical fibers, a method used before. But there were also links carried by lasers aimed from one facility to another. The lasers, however didn’t work during a snowstorm, but when they did work the results were comparable to the optical fiber method.

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