a microwave-oven with animated wave diagram

Dive Into The Microwaves, The Water’s Dipolar

March 27, 2023 by Michael Shaub 22 Comments

When the microwave oven started to gain popularity in the 60s and 70s, supporters and critics alike predicted that it would usher in the end of cooking as we knew it. Obviously that never quite happened, but not because the technology didn’t work as intended. Even today, this versatile kitchen appliance seems to employ some magic to caffeinate or feed a growing hacker in no time flat. So, how exactly does this modern marvel work?

That’s exactly what [Electronoob] set out to explain in his latest video. After previously taking apart a microwave and showing off the magnetron within he’s back with a clear explanation of how these devices work.

Maybe you have no idea, or have heard something vague about the water in the food wiggling in response to the microwaves. Do you know why microwaves and not some other part of the electromagnetic spectrum? Why the food spins on a platter? How the size of the oven relative to the wavelength affects the efficiency of its cooking? We didn’t, and think the video is a great primer on all of this and more.

Here at Hackaday, we sure love using and abusing microwave ovens. From upgrading them with voice control back in 2013, to turning them into UV curing chambers and mini foundries, to the limitless possibilities for the transformers and magnetrons that await us inside, we just can’t get enough. (this is our 82nd article tagged with microwave!)

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Another Magnetron Teardown

December 22, 2022 by Al Williams 22 Comments

[Electronoobs] has a healthy respect for the voltages and ceramics inside a microwave oven. But he still found the courage to tear one apart and show us the insides and characterize some of the components. You can see the video of the teardown below.

The danger of the voltage is obvious. However, there is also a ceramic insulator inside. Some of them are made from aluminum oxide, but others are made with beryllium oxide. You probably don’t want to inhale either one, but beryllium oxide, if powdered, can cause serious health problems. Obviously, you need to be careful if you decide to rip your oven open. Of course, the other danger is if you put the oven back together and try to use it. You need to ensure all the shielding is back in the proper place.

The video shows the operation of several of the components using test equipment and, in some cases, some surrogate components. The animation of an LC oscillator is very easy to understand. However, when he actually cuts into the magnetron with a rotary tool, you can really see how the device works. Some animations make it even clearer.

We haven’t seen a magnetron teardown for a few years. You can do many things with a magnetron from radar to vacuum deposition of films.

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Sputtering Daguerreotypes, Batman!

August 15, 2022 by Elliot Williams 14 Comments

The Daguerreotype was among the earliest photographic processes, long before glass plates or film, that relied on sensitizing a thin layer of silver on top of a copper plate. The earliest Daguerreotype plates were made physically, by rolling a copper-silver plate thinner and thinner until the silver layer was just right. Good luck finding a source of Daguerreotype plates made this way in 2022. (There are electroplating methods, but they all end up with chemically contaminated silver.)

On the other hand, magnetron sputtering is a process of depositing pure metal in thin layers using plasma, high voltages, and serious magnets, and [Koji Tokura] is making his own sputtered Daguerreotype plates this way, giving him the best of both worlds: the surreal almost-holographic quality of the Daguerreotype with the most difficult film preparation procedure imaginable.

The star of the show is [Koji]’s sputtering rig, which consists of a Tupperware glass sandwich box as a vacuum chamber and a microwave oven transformer as the high voltage source. In use, he pumps the chamber down, introduces a small amount of argon, and then lights up the plasma. The high voltage accelerates the plasma ions into a sheet of silver, and the silver particles that get knocked free coat the copper plate. A strong magnet creates a local plasma, which accelerates the coating procedure, but since [Koji] only had a relatively small magnet, he scans the plate with the magnet, using a scavenged 2D pen plotter mechanism.

Check out his video on the Hackaday.io page, and his Daguerreotype gallery as well. (We don’t think that they were all made with this procedure.)

The result is a chemically pure Daguerreotype plate produced in a seriously modern way, and we’d love to see the images in person. In these days of disposable images made by the AIs in your cell phone, it’s nice to see some people taking photography in strange directions. For instance, maybe you’d like to make your own ultra-large collodion plates. Or something else? If you do, show us!

Microwave Ovens: Need More Power? Use Lasers Instead!

September 28, 2021 by Dave Rowntree 15 Comments

You know how it is, you get in late from work, you’ve been stuck in traffic for what seems like an eternity, and you’re hungry. You reach for the microwave meal, and think, if only I didn’t have to wait that three-and-a-half minutes, 900 watts just isn’t enough power. What you need is a laser microwave, and as luck would have it, [Styropyro] has built one, so you don’t have to. No, really, don’t.

After he observed a microwave only operating on a half-wave basis, and delivering power 50% of the time, he attempted to convert it to full-wave by doubling up the high voltage transformer and rectification diodes. While this worked, the poor suffering magnetron didn’t go the full mile, and died somewhat prematurely.

Not to be disheartened, the obvious thing was to ditch the whole concept of cooking with boring old radio waves, and just use a pile of frickin’ lasers instead. Now we’re not sure how he manages to get hold of some of the parts he uses, and the laser array modules look sketchy to say the least, and to be frank, we don’t think they should be easy to get given the ridiculous beam power they can muster.

With the build completed to the usual [Styropryo] level of excellent build quality, he goes on to produce some mouthwatering delicacies such as laser-charred poptart, incinerated steak with not-really-caramelised onions and our favourite laser-popcorn. OK, he admits the beam has way too much power, really should be infrared, and way more diffuse to be even vaguely practical, but we don’t care about practicality round these parts. Who wouldn’t want the excitement of going instantly blind by merely walking into the kitchen at the wrong time?

We’ve covered a fair few microwave oven related hacks before, including a neat microwave kiln, and hacks using microwave parts, such as a janky Jacob’s ladder, but this is probably the first laser microwave we’ve come across. Hopefully the last :)

And remember kids, as [Styropyro] says in pretty much every video on his channel:

All the crazy stuff I’m about to do was done for educational purposes, in fact if you were to try any of this stuff at home, you’d probably die…

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Swap Your Microwave For A High Voltage Stereo

May 30, 2020 by Bryan Cockfield 31 Comments

When building a new project, common wisdom suggests to avoid “reinventing the wheel”, or doing something simple from scratch that’s easily available already. However, if you can build a high-voltage wheel, so to speak, it might be fun just to see what happens. [Dan] decided to reinvent not the wheel, but the speaker, and instead of any conventional build he decided to make one with parts from a microwave and over 6,000 volts.

The circuit he constructed works essentially like a Tesla coil with a modulated audio signal as an input. The build uses the high voltage transformer from the microwave too, which steps the 240 V input up to around 6 kV. To modulate that kind of voltage, [Dan] sends the audio signal through a GU81M vacuum tube with the support of a fleet of high voltage capacitors. The antenna connected to the magnetron does tend to catch on fire somewhere in the middle of each song, so it’s not the safest device around even if the high voltage can be handled properly, but it does work better than expected as a speaker.

If you want a high-voltage speaker that (probably) won’t burn your house down, though, it might be best to stick to a typical Tesla coil. No promises though, since working with high voltages typically doesn’t come with safety guarantees.

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A Magnetron Tear Down

December 5, 2019 by Al Williams 27 Comments

Microwave ovens are everywhere, and at the heart of them is a magnetron — a device that creates microwaves. [DiodeGoneWild] tore one apart to show us what was inside and how it works. If you decide to do this yourself, be careful. The magnetron may have insulators made of beryllium oxide and inhaling dust from the insulator even one time can cause an incurable lung condition.

Luckily, you can’t get a lung problem from watching a video. In addition to just seeing the guts of the magnetron, there are also explanations about how everything works with some quick sketches to illustrate the points.

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