Hack Makes Microwave Cookies Fast And Not Terrible

March 11, 2024 by Dan Maloney 35 Comments

Making a chocolate chip cookie is easy. Making a good chocolate chip cookie is a little harder. Making a good chocolate chip cookie quickly is a pretty tall order, but if you cobble together a microwave and a conventional oven, you just might get delicious and fast to get together.

The goal of this Frankenstein-esque project is to build a vending machine that can whip up a fresh-baked chocolate chip cookie on demand and make [Chaz] wealthy beyond his wildest dreams. We’re guessing at that last part; for all we know his goal is world peace through instant cookies. We’re fine with the idea either way, and his previous work on the project resulted in a semi-automatic cookie gun to splooge the dough out in suitable dollops.

The current work is turning those into something edible, for which a microwave seems a logical choice. Experience tells us otherwise, so off to the thrift store went [Chaz], returning with a used air fryer. He ripped the guts out of a small microwave, slapped the magnetron onto the side of the air fryer, and discovered that this was officially A Bad Idea™ via a microwave leakage tester. Round 2 went the other way — adding a conventional heating element to a large microwave. That worked much better, especially after close-up video revealed the dynamics of microwave cookery and the best way to combine the two cooking modalities. The result is a contraption that makes a pretty tasty-looking two-minute cookie. World peace, here we come!

Of course there’s plenty to say about the safety of all this, much of which [Chaz] himself cops to in the video. It’s important to remember that he’s just prototyping here; we’re sure the final machine will be a little more sophisticated than a heat gun duct-taped to the side of a microwave. Those cookies aren’t going to bake themselves, though, so you’ve got to start somewhere.

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Powering A Cavity Magnetron, From A Battery

December 4, 2023 by Jenny List 47 Comments

While vacuum electronic devices have largely been superseded over much of consumer electronics, there’s one place where they can still be found for now. The cavity magnetron is a power RF oscillator device in which electrons are induced to move in a circular path through a tuned cavity, inducing a high-power RF field, and it lies at the heart of a domestic microwave oven. They usually need a high-voltage mains transformer and a rectifier to work, but [Hyperspace Pirate] has managed to make a solid-state power supply to power one from a 12 volt battery. Better still, he’s put the resulting combo in a Care Bears lunchbox. Take a look at the video below the break.

The video starts with a potted history of the magnetron before looking at the circuit of a typical oven, which uses a single diode and a capacitor in a simple voltage multiplier. The capacitor value is adjusted to lower the power output, and a pretty thorough job is done of characterising the circuit.

The low-voltage supply starts with an XVS inverter to make the high voltage via another multiplier, but the interesting part comes with the magnetron’s heater. It’s designed for 50 or 60Hz household electricity, but there it’s receiving 40 kHz and has an appreciable impedance. The addition of a capacitor soon restores it to a reasonable performance.

In case you noticed that the ZVS converter might be improved upon, take a look at a flyback converter. Meanwhile, we should probably echo the safety message in the video that playing with magnetrons and their associated transformers can be a nasty way to die. Please take care out there!

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The Device That Won WW2: A History Of The Cavity Magnetron

August 28, 2023 by Adam Fabio 55 Comments

[Curious Droid] is back with a history lesson on one of the most important inventions of the 20th century: The cavity magnetron. Forged in the fighting of World War II, the cavity magnetron was the heart of radar signals used to identify attacking German forces.

The magnetron itself was truly an international effort, with scientists from many countries providing scientific advances. The real breakthrough came with the work of [John Randall] and [Harry Boot], who produced the first working prototype of a cavity magnetron. The device was different than the patented klystron, or even earlier magnetron designs. The cavity magnetron uses physical cavities and a magnetic field to create microwave energy. The frequency is determined by the size and shape of the cavities.

While the cavity magnetron had been proven to work, England was strapped by the war effort and did not have the resources to continue the work. [Henry Tizzard] brought the last prototype to the USA where it was described as “the most valuable cargo ever brought to our shores”. The cavity magnetron went on to be used throughout the war in RADAR systems both air and sea.

Today, many military RADAR systems use klystrons or traveling wave tube amplifiers due to requirements for accurate frequency pulses. But the cavity magnetron still can be found in general and commercial aviation RADAR systems, as well as the microwave ovens we all know and love.

Check the video out after the break.

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Ku-Go: The World War II Death Ray

August 11, 2023 by Al Williams 66 Comments

Historians may note that World War II was the last great “movie war.” In those days, you could do many things that are impossible today, yet make for great movie drama. You can’t sneak a fleet of ships across the oceans anymore. Nor could you dig tunnels right under your captor’s nose. Another defining factor is that it doesn’t seem we seek out superweapons anymore.

A Churchill Bullshorn plough for clearning minefields — one of Hobart’s “Funnies”

Sure, we develop better planes, tanks, submarines, and guns. But we aren’t working on anything — that we know of — as revolutionary as a rocket, an atomic bomb, or even radar was back in the 1940s. The Germans worked on Wunderwaffe, including guided missiles, jets, suborbital rocket bombers, and a solar-powered space mirror to burn terrestrial targets. Everyone was working on a nuclear bomb, of course. The British had Hobart’s Funnies as well as less successful entries like the Panjandrum — a ten-foot rocket-driven wheel of explosives.

Death Ray

Perhaps the holy grail of all the super weapons — both realized and dreamed of was the “death ray.” Of course, Tesla claimed to have one that didn’t use rays, but particles, but no one ever successfully built one and there was debate if it would work. Tesla didn’t like the term death ray, partly because it wasn’t a ray at all, but also because it required a huge power plant and, therefore, wasn’t mobile. He envisioned it as a peacekeeping defensive weapon, rendering attacks so futile that no one would dare attempt them.

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Hackaday Links: May 14, 2023

May 14, 2023 by Dan Maloney 13 Comments

It’s been a while since we heard from Dmitry Rogozin, the always-entertaining former director of Roscosmos, the Russian space agency. Not content with sending mixed messages about the future of the ISS amid the ongoing war in Ukraine, or attempting to hack a mothballed German space telescope back into action, Rogozin is now spouting off that the Apollo moon landings never happened. His doubts about NASA’s seminal accomplishment apparently started while he was still head of Roscosmos when he tasked a group with looking into the Apollo landings. Rogozin’s conclusion from the data his team came back with isn’t especially creative; whereas some Apollo deniers go to great lengths to find “scientific proof” that we were never there, Rogozin just concluded that because NASA hasn’t ever repeated the feat, it must never have happened.

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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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