Want To Learn Binary? Draw Space Invaders!

February 24, 2024 by Elliot Williams 6 Comments

This was the week that I accidentally taught my nearly ten-year-old son binary. And I didn’t do it on purpose, I swear.

It all started innocently enough. He had a week vacation, and on one of those days, we booked him a day-course for kids at our local FabLab. It was sold as a “learn to solder” class, and the project they made was basically a MiniPOV: eight LEDs driven by a museum-piece AVR ATtiny2313. Blinking lights make a pattern in your persistence of vision as you swipe it back and forth.

The default pattern was a heart, which is nice enough. But he wanted to get his own designs in there, and of course he knows that I know how to flash the thing with new code. So I got him to solder on an ISP header and start drawing patterns on grids of graph paper while I got the toolchain working and updated some of the 2000’s-era code so it would compile.

There’s absolutely no simpler way to get your head around binary than to light up a row of LEDs, and transcribing the columns of his fresh pixel art into ones and zeros was just the motivation he needed. We converted the first couple rows into their decimal equivalents, but it was getting close to dinner time, so we cheesed out with the modern 0b00110100 format for the rest. This all happened quite organically; “unintentional parenting” is what we call it.

While we were eating dinner, I got the strangest sense of deja vu. When I was around ten or eleven, my own father told me about the custom fonts for the Okidata 24-pin printer at his lab, because he needed me out of his hair for a while, and I set out to encode all of the Hobbit runes for it. (No comment.) He must have handed me a piece of graph paper explained how it goes, and we had a working rune font by evening. That was probably how I learned about binary as well.

Want to teach someone binary? Give them a persistence of vision toy, or a dot-matrix printer.

(Art is from a much older POV project: Trakr POV — a hack of an old kids’ toy to make a long-exposure POV image. But it looks cool, and it gets the point across.)

You Got Fusion In My Coal Plant!

February 24, 2024 by Navarre Bartz 48 Comments

While coal was predominant in the past for energy generation, plants are shutting down worldwide to improve air quality and because they aren’t cost-competitive. It’s possible that idle infrastructure could be put to good use with fusion instead.

While we’ve yet to see a fusion reactor capable of generating electricity, Type One Energy, the Tennessee Valley Authority, and Oak Ridge National Lab have announced they’re evaluating the recently-closed Bull Run Fossil Plant in Oak Ridge, Tennessee as a site for a nuclear fusion reactor. One of the main advantages for siting any new generation source on top of an old one is the ability to reuse the existing transmission infrastructure to get any generated power to the grid.

Don’t get too excited as it sounds like this is yet another prototype reactor that will be the proof-of-concept before construction of a reactor that can produce commercial power for the grid. While ambitious, the amount of investment by government entities like the Department of Energy and the state of Tennessee (>$55 million) seems to indicate they aren’t just blowing smoke.

If any of this seems familiar, you might be thinking of the Department of Energy’s report on placing advanced fission reactors on old coal sites. A little fuzzy on the difference between a stellarator and a tokamak? Checkout this explainer on some of the different ways to (non-explosively) do fusion on Earth.

Your Scope, Armed And Ready

February 24, 2024 by Al Williams 13 Comments

[VoltLog] never has enough space on his bench. We know the feeling and liked his idea of mounting his oscilloscope on an articulated arm. This is easy now because many new scopes have VESA mounts like monitors or TVs. However, watching the video below, we discovered there was a bit more to it than you might imagine.

First, there are many choices of arms. [VoltLog] went for a cheap one with springs that didn’t have a lot of motion range. You may want something different. But we didn’t realize that many of these arms have a minimum weight requirement, and modern scopes may be too light for some of these arms. Most arms require at least 2 kg of weight to balance the tensions in their springs or hydraulics. Of course, you could add a little weight to the mounting plate of the arm if you needed it. The only downside we see is that it makes it hard to remove the scope if you want to use it somewhere else.

Assuming you have a mount you like, the rest is easy. Of course, your scope might not have VESA mounting holes. No problem. You can probably find a 3D printed design for an adapter or make (or adapt) your own. You might want to print a cable holder at the same time.

Honestly, we’ve thought of mounting a scope to the wall, but this seems nicer. We might still think about 3D printing some kind of adapter that would let you easily remove the scope without tools.

Of course, there is another obvious place to mount your scope. Monitor arms can also mount microscopes.

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MovieCart Plays Videos On The Atari 2600

February 23, 2024 by Lewin Day 12 Comments

The original Xbox and PlayStation 2 both let you watch DVD movies in addition to playing games. Seldom few consoles before or since offered much in the way of media, least of all the Atari 2600, which was too weedy to even imagine such feats. And yet, as covered by TechEBlog, [Lodef Mode] built a cartridge that lets it play video.

It’s pretty poor quality video, but it is video! The MovieCart, as it is known, is able to play footage at 80×192 resolution, with a color palette limited by the capabilities of the Atari 2600 hardware. It’s not some sneaky video pass-through, either—the Atari really is processing the frames.

To play a video using the MovieCart, you first have to prepare it using a special utility that converts video into the right format for the cart. The generated video file is then loaded on a microSD card which is then inserted into the MovieCart. All you then have to do is put the MovieCart into the Atari’s cartridge slot and boot it up. Sound is present too, in a pleasingly lo-fi quality. Control of picture brightness and sound volume is via joystick. You could genuinely watch a movie this way if you really wanted to. I’d put on House of Gucci.

Thanks to the prodigious storage available on microSD cards, you can actually play a whole feature length movie on the hardware this way. You can order a MovieCart of your very own from Tindie, and it even comes with a public domain copy of Night of the Living Dead preloaded on a microSD card.

We don’t see a big market for Atari 2600 movies, but it’s neat to see it done. Somehow it reminds us of the hacked HitClips carts from a while ago. Video after the break.

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Mirror, Mirror, Electron Mirror…

February 23, 2024 by Al Williams 2 Comments

If you look into an electron mirror, you don’t expect to see your reflection. As [Anthony Francis-Jones] points out, what you do see is hard to explain. The key to an electron mirror is that the electric and magnetic fields are 90 degrees apart, and the electrons are 90 degrees from both.

You need a few strange items to make it all work, including an electron gun with a scintillating screen in a low-pressure tube. Once he sets an electric field going, the blue line representing the electrons goes from straight to curved.

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Reggaeton-Be-Gone Disconnects Obnoxious Bluetooth Speakers

February 23, 2024 by Bryan Cockfield 29 Comments

If you’re currently living outside of a Spanish-speaking country, it’s possible you’ve only heard of the music genre Reggaeton in passing, if at all. In places with large Spanish populations, though, it would be more surprising if you hadn’t heard it. It’s so popular especially in the Carribean and Latin America that it’s gotten on the nerves of some, most notably [Roni] whose neighbor might not do anything else but listen to this style of music, which can be heard through the walls. To solve the problem [Roni] is now introducing the Reggaeton-Be-Gone. (Google Translate from Spanish)

Inspired by the TV-B-Gone devices which purported to be able to turn off annoying TVs in bars, restaurants, and other places, this device can listen to music being played in the surrounding area and identify whether or not it is hearing Reggaeton. It does this using machine learning, taking samples of the audio it hears and making decisions based on a trained model. When the software, running on a Raspberry Pi, makes a positive identification of one of these songs, it looks for Bluetooth devices in the area and attempts to communicate with them in a number of ways, hopefully rapidly enough to disrupt their intended connections.

In testing with [Roni]’s neighbor, the device seems to show promise although it doesn’t completely disconnect the speaker from its host, instead only interfering with it enough for the neighbor to change locations. Clearly it merits further testing, and possibly other models trained for people who use Bluetooth speakers when skiing, hiking, or working out. Eventually the code will be posted to this GitHub page, but until then it’s not the only way to interfere with your neighbor’s annoying stereo.

Thanks to [BaldPower] and [Alfredo] for the tips!

Op-Amp Drag Race Turns Out Poorly For 741

February 23, 2024 by Dan Maloney 32 Comments

When it was first introduced in 1968, Fairchild’s 741 op-amp made quite a splash. And with good reason; it packed a bunch of components into a compact package, and the applications for it were nearly limitless. The chip became hugely popular, to the point where “741” is almost synonymous with “op-amp” in the minds of many.

But should it be? Perhaps not, as [More Than Electronics] reveals with this head-to-head speed test that compares the 741 with its FET-input cousin, the TL081. The test setup is pretty simple, just a quick breadboard oscillator with component values selected to create a square wave at approximately 1-kHz, with oscilloscope probes on the output and across the 47-nF timing capacitor. The 741 was first up, and it was quickly apparent that the op-amp’s slew rate, or the rate of change of the output, wasn’t too great. Additionally, the peaks on the trace across the capacitor were noticeably blunted, indicating slow switching on the 741’s output stage. The TL081 fared quite a bit better in the same circuit, with slew rates of about 13 V/μS, or about 17 times better than the 741, and nice sharp transitions on the discharge trace.

As [How To Electronics] points out, comparing the 741 to the TL081 is almost apples to oranges. The 741 is a bipolar device, and comparing it to a device with JFET inputs is a little unfair. Still, it’s a good reminder that not all op-amps are created equal, and that just becuase two jelly bean parts are pin compatible doesn’t make them interchangeable. And extra caution is in order in a world where fake op-amps are thing, too.

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