I worked on radar systems since the mid-seventies in Marine aviation. I have had a basic understanding of magnetron operation all these years and even taught electronic theory as an instructor, but this was the clearest, most accurate description of what is truly happening, that I've ever heard. Thanks!
@@JohnNy-ni9np...its adjustable for military purposes. Long range dissipation is very high. A so called horn focuses the beam. A ordinary sheet of aluminum foil can already protect 100% by reflection.
I was in tactical communications in the Army in the late 80's and early 90's and we used a 5 cavity tunable Klystron as our High Power Amplifier. All the basics are pretty much the same. You do a VERY good job of breaking this down and explaining this function. I really enjoyed this video. Thanks.
FINALLY. after about 20 videos, I find a good explanation of the cavity magnetron! Thank you. Whoever took the components & operation of a discrete LC circuit and recreated the effect in a solid lump of copper by just using geometry was a genius.....pure inspiration.
I was a US Navy electronics technician in the mid-60's so I feel I have a better-than-average understanding of the science. Your explanation of the principles behind the magetron are, by far, the best I've ever seen. I especially highlight your illustration of capacitive-magnetic resonance. You have done an excellent job!
Dont worry - an insulator of the RF output feeder is not made from beryllium oxide ceramic. Nobody, even Chinese, makes domestic equipment with it. This one is made from Al2O3 with a little manganese doping which defines its color. So yep, basically this is a technical ruby ceramic. Also you can do a simple test when in doubt of containing beryllium - just flash a 360-365 nm UV light on it: corundum ceramics will luminescence with deep red ruby-color and beryllium ceramic shows a weak purple luminescence. BTW, if anybody interests, the kitchen oven magnetron is just one of the big family - in other magnetron types, like pulsed for radar, coax-type, relativistic MILO or spatial-harmonics mode, the construction and electric field patterns are much more complex but working principle is close the same.
Best description of how a cavity magnetron works I've ever seen. One thing to point out though "This could melt you from the inside out without you even knowing" You *will* feel burns from microwaves in the 2.4Ghz (yeah, microwave ovens use the same frequency as old WiFi) region, they vibrate water molecules so you will definitely notice the burning. Microwaves are used in crowd dispersion devices (higher frequencies, less penetration) because you can feel them and they *hurt.* The high voltage is a hazard, but a microwave isn't going to cause burns much more serious than a 2000 watt IR heater, especially at a distance. A microwave oven exploits the fact that the waves bounce and are close to the magnetron. If you turn it on outside the enclosure you're more likely to damage sensitive electronics as well as draw the wrath of whoever governs RF frequencies where you live than get badly burned.
Yeah I've seen a guy comment on a similar video, he thought the oven stopped working so he put his head inside to check something out and he described the feeling as getting very dizzy, but nothing more serious. And it's the brain we're talking about, so it's definitely not that dangerous. And anyway it takes a while to get some heat to build up, with the brain thing it wouldn't be a surprise if the actual molecular vibration does something weird rather than heat alone.
In addition to the correct statements you and @Techalyzer have already made, microwaves also just don't penetrate that far. When cooking food, anything more than about 1" thick will heat much more slowly. For practical purposes, if you can arrange the food to reduce thickness, including putting an indentation in the middle of malleable solids like rice, mashed potatoes, etc., you can heat the food more evenly and quickly. For humans, this means that yes, some potential for injury exists if one really just ignores the pain involved before things get hot enough, but it's unlikely organs deep in the body would be affected much if at all.
I wonder if is this going on in Ukraine. During the Bosnian war very expensive anti radar site missiles would get to blow up decoys made of ovens rigged to operate with the door open. Probably the highest ratio of cost to kill ratio of any tech warfare kit.
@@echodelta9 Shortwave diathermy machines were used for similar purposes in WWII, though instead of disrupting radar seeking missiles they disrupted a radio beam intersect used by bombers. IIRC it was called the battle of the beams.
Thank you! I have seen multiple explanations how a magnetron works in textbooks with drawings, but it makes much more sense for me seeing the inside of it. Also your explanation was better than my 100€ physics textbrick. It finally makes sense.
The electrons alone won't cause any radiation, even when you spin them by the magnet. What makes the microwave energy is the combination of the electrons moving aronund the cavities, forming a kind of "electron whistle" (the theory is a bit more complicated, but on some aspects the electron movement becomes somewhat similar to what the air does in the regular whistle). The high voltage combined with the magnets is use to make the electrons to move along the cavity tops to form that whistle, without the magnetic field they would just fly straight into the cavities, so no whistle.
Actually they do and the video explained that. Any electron that undergoes acceleration releases photons. He said the magnets were put there to make it "more efficient".
it's about resonannnnnnnnce. RF is all about resonance, really. What frequencies and what proportions -- and especially geometry. The magnets provide a field for the electrons to surf against and curve into a spiral, it's together with the force of the electric field reacting against the uniform magnetic field that creates motion at a right-hand independent vector. The electric waves radiating out of the center would merely be attenuated by reflection by the LC tank of the copper cavity, but realistically I'd wonder if it would just cease to operate from damage overheating after a short time without the needed magnetic field to transform the radiated energy into EM waves with transmission capability.
dude, standing o. Been watching your channel for a while and your visuals and explanation game went exponential recently like 3B1B or Steve Mould or ElectroBOOM level. Keep up the great work.
I like this teardown. Subscribed! It needs to be mentioned that the magnetron receives high voltage DC as well as a very low voltage AC from the transformer secondary coils. One secondary coil puts out about 1400VAC, is rectified with a diode and doubled to 2800VDC as it charges and discharges the capacitor in phase. This is connected to the cathode of the magnetron through one of the filament connections. The other secondary coil is a high current 3VAC and is responsible for heating the filament in the magnetron.
I worked in a reprocessing plant for electron RF vac tubes. From a very small 1.5Kw to a huge 357lb (with water jacket) 3.2 Gw vacuum tube and all sorts in between. I learned a lot. How electrons are emitted and controlled by electromagnet oscillation. This video was very informative and not overly technical. Thanks for a job well done.
A warning about that few kV capasitor would be nice, since old ones might not be able to discharge themselfes on their own anymore (built-in resistor could burn out over time), so during disassembly it's always good to check by bridging the leads with some conductor with a good isolated grip/preferably on a stick.
Good general advice for any power supply, really. For really high voltage stuff in the Navy, we had shorting probes and, in extreme cases, thick rubber gloves. I want to say protection up to around 30Kv with both. Which reminds me of an actual maintenance check documented in the technical manual for an air search radar I worked on, that dated back to the 50's or so. It was called the "tinfoil test" and was a way to test the "crowbar" circuit that was supposed to shut down the radar's high voltage in the event of a short. You would take a piece of foil and wrap it around the end of the copper rod of the shorting probe, fanning it out for a couple of inches. Then, you would glove up, open the cabinet to get access to the high voltage connection, connect the probe's ground clip, then bring that fanned out piece of foil, slowly, close to the HV connection. Before you make contact, it'll arc to the foil, burning a hole in it, until the crowbar kicks in and shuts it down. You then measure the size of the hole burnt in the foil. If the hole is too big, the crowbar was too slow, and it fails the test. I got to be first in my class at school to do that test. Makes a rather startling pop, too. 🙂
I used to repair microwave ovens. I've stripped lots of them. The reality is that if you test the capacitor, the voltage is gone in seconds. It's all BS.
To test a magnetron , you measure the voltage at the terminals. If the magnetron is dead, you'll get maybe 2.2KV and if it's good and drawing current it will drop to about 1.9KV. Got to use a high voltage 1000 times probe in the meter to measure
What a brilliant video! After just replacing a faulty magnetron in my microwave oven I was interested to find out what is inside one and your video explained it perfectly with a great explanation and clear animations. Thanks! I had already pulled the faulty unit apart to salvage the magnets and was aware of not breaking the ceramic insulators, but hadn't gone so far as dremelling the copper anode. I have subscribed. My microwave is an inverter model to vary output power and doesn't seem to have the large capacitor. There are smaller ones on the inverter PCB. It would be interesting to see a video on how inverter microwave ovens work. Thanks again.
Thank you for doing this video Andrei. Microwaves are something I've been curious about for some time. I really enjoy the animations you put into your explanations. I'm looking forward to the next video on this topic.
This is the best description of a magnetron I've ever seen. Great video! You should do one on a 555 timer if you haven't already. I'd love to watch that.
Great video! One mistake I noticed though was in the explanation of LC circuit oscillation. The mistake was the presence of a magnetic field in the inductor when no current was flowing, at 6:59 and other moments, and reasoning that the collapse of the magnetic field at 7:05 is what resets the polarity of the capacitor. Instead, what actually happens is the magnetic field would begin to collapse once the voltage across the capacitor is 0V and the current is maximum, at about 6:54 in your animation. Only THEN would the magnetic field have collapsed, and the inductor would oppositely charge the capacitor to how it is seen at 6:59. I love EM, so I couldn't let this little inaccuracy slide ;) Cheers!
hahahahah thank you. The presence of a "static magnetic field" is actually just a pause in the animation while explaining. In real life it would be fast as you say, the field collapsing after the voltage passes the threshold.
@@ELECTRONOOBS You're welcome! Just wanted to clarify that an inductor's magnetic field will only collapse in this circuit when the voltage across the capacitor is zero.
I believe you got something wrong there, as the magnetic field is proportional to the current in the inductor, so the magnetic field has its maximum amplitude when the capacitor voltage is zero. Thinking if it in another way: Energy must be conserved, so when theres no cahrge in the capacitor (0 V) The energy must all be stored in the magnetic field
I have done years of magnetron research but have never until now seen a presentation suitable for an introductory physics or engineering course. Great job!
Amazingly informative video. I learned so much. Also learned I should handle those insulators with more care 😬. Ive taken apart a number of microwaves but never knew what it looked like inside the copper high voltage diode, really interesting way to use induction.
What a great teardown! I've long wondered about the mysterious workings of that magic box in the kitchen. I've always been told not to tear one of those apart for fun. Now I know what to do and not do. You earned the subscription, thanks for that great presentation
I always wondered how mangnetrons worked. Thank u for creating such a great content so that any newbie could understand how things works. Now I wonder how genius are those who designed this😇
Very good presentation. I was trained at Varian Assoc. in my earlier years, designing and making both magnetrons and klystrons. It was all about copper, powerful electromagnets, EHT, shf, amps and heat. Our klystrons were used for both radar and TV transmitters and consumed many 100's KW of mean power. The ones I worked on not only emitted microwaves but incidently X-rays which had to checked for safety. The vacuums were typically down to 10^-12 torr if I remember correctly provided by ion pumps. Cant go into too much details (frequencies, output power etc) for obvious reasons but I believe most of this technology has moved over to Solid State!
@@cherylm2C6671 Quite a lot, I studied electromagnetism (Maxwell) and the maths in my own time, linear algebra and basic electrical theory. Our company was also working on the new X-Ray Tomography machines just coming into production. I worked in the section designing and making the cavities, so had to learn to use machine tools as well, to very high tolerances I may add. The smallest klystrons were used by jet aircraft in the nose cones, these were much higher frequencies (X band) but much less powerful.
Thanks for this video explaining how the cavity magnetron works. I have made a video showing how to troubleshoot simpler microwave ovens similar to yours. I simply explained that the transformer, diode, and capacitor can be tested easily with common meters and tools; and that if you confirm they are all good but there is still no heating, the magnetron can be suspect by process of elimination. My mom still has her 1988 year Sharp microwave. Its original magnetron lasted until 2020. Very well made product! I was able to get a used magnetron from eBay for a few dollars and get it going again without problems. Thanks again for your good explanation!
@@cherylm2C6671 You're welcome. I'll post a link to the video in the next comment. If you only see one comment then it means UA-cam is blocking the link.
Thanks for all the safety tips and discharging the capacitors are important also, which can be deadly if touched before properly discharged, thanks for all the details, the transformer can be used to make a spot welder for small projects
Though video was pretty good, i would like to mention that ''the metal sheath'' you mentioned on the beginning of the video is actually made of mica, and it is interchangeable. If it gets pounced, it can be replaced , and the microwave oven is good as new.
@@cherylm2C6671 I used a plastic film on one of my ovens and it worked for many years with no visible damage. I think that mica is used just as a "worst case scenario", the area doesn't usually get very hot during normal operation.
@@techalyzer I will try that! Thank you for your suggestion! That will make cleaning easier than pushing on that mica plate. break. Fats (or bits of exploded egg) kept away from the magnetron.
Very interesting. You could reuse from 8:00 to 14:00 in a video comparing the magnetron with how a Radar Vacuum tube achieves frequencies and speculate why we do not use tubes in microwaves ( excluding manufacturing as when commercial microwaves started being made, there were vacuum tube manufacturers that could do it ).
Simple reason is cost and efficiency, magnetrons are over 50% effective at generating microwaves, and need no excitation at all, where transmitter tubes need both an exciter stage to drive them, and also filters on the output, plus the typical efficiencies of around 30% is a big drawback, and also the volume they need. Magnetron combines self exciting, and built in filtering cavity filters in it's design, so it is a single part.
What do you mean by "Radar vacuum tube"? Magnetrons _are_ vacuum tubes. Indeed, they are used for certain types of RADAR too. Klystrons aren't altogether too dissimilar in working principle either but they're specifically set up to be able to amplify a signal, whereas a cavity magnetron can only really act as a local oscillator. Handheld RADAR guns use solid state devices (Gunn diodes) and there are now power FET devices that can operate well into the mw band, but when theres no need for a high fidelity, low noise amplifier and all you need is raw RF energy it's pretty tough to beat the humble cavity magnetron.
@@whatelseison8970 The ORIGINAL vacuum tubes used for RADAR had a micro disc inside as the resonator with specific gaps on the inner circumference for the RADAR frequency instead of the size of copper chunk inside a microwave oven. It appears if you increase the size, triple the wattage you can achieve the same frequencies and higher without being in a vacuum.
Thank you for your comment. A radio science newbie is always looking for analog applications. There is still plenty of work for vacuum tube in the industry.
Theoretically microwaves don't come from the hole of the antenna, but really from the insulator, 8:55 those are actually the Heater inputs, anode is grounded on a magnetron, btw nice video
Thank you so much for your video! Your video is the best I have seen on the internet. I will visit again. This is a better explanation and I can take notes and anticipate doing something with this- I'd better thank you!
Back in the 70's, at ET "A" school in the Navy, I taught these things. Something like this video would have been nice back then. I made do with drawing a cross section on a chalkboard and trying to describe the electron flow that way. Animation is so much nicer. Our animation was Army films from back when radar was invented, mostly cartoons with sgts yelling and hearing echos. I always found the reflex klystron intriguing, with its re-entrant cavity. The visualization reminded of a popcorn popper, electrons flying up through the cavity, seeing the repeller plate, and reversing back to the cavity. One of the weirder devices, but kind of fun to teach. TWTs, on the other hand. We really only touched on them, and I never worked on them. Taught a brief segment on them, can't say as I really understood them that well, myself. I can say, however, I can remember having to change how we referred to them while I was there. The change happened as we started getting women coming through the school. Before, when we talked about TWTs, they were amplifying tubes. After, we had to refer to them as intensifying tubes. Because we used an acronym to refer to them, and I'll just leave it at that.
@@brolinofvandar Known as Twits in my SatCom days, Did all the theory during my apprenticeship training, now long forgotten. Still makes me shudder working on water cooled klystrons, power off of course, but nevertheless, had to be done.
The safest, for me most useful, component from a scrapped microwave oven is the timer. I kept on forgetting my solder iron, leaving it on overnight until I connected via the timer. I prolly will do an upload to show how it was done. Love these teardowns! Thanks. 🙂
Years ago i took the display/keypad/controller assembly off an old microwave oven and attached a power cord to it and hung it on the wall in the garage. Makes a great wall clock with count down timer and beeper all built in. Great conversation piece.
The 2100 volts capacitor filters de AC current from the transformer. The anode needs at least 2kv to work. This high voltage comes from the transformer working as elevator from 230v. Very good explanation. Thanks.
around 13:22 , you said that the microwave transformer generates around 300V AC! i know its just a typo and in the captions it says correctly as 3000V but to just let you know, i pointed this out. Nice video man as always, hats off to you! keep making such informative content🔥🔥🔥
I worked at a microwave plant in the 90's and would go through the "dud" pallets of magnetrons getting tossed into the scrap dumpster to get all the ceramic magnets out of them. NOW I know how those crazy things work. Thank you!
Excellent video. I'd like to add a suggestion: When explaining tne 'capacitor' (formed by a sudden carved section on the copper rod), the electrons closer to the travelling one should be presentend getting away from it... creating the depleted area.
3:55 it doesn't actually shoot out of that hole like a gun. It radiates around the ring almost like an omnidirectional antenna. thus why waveguides are needed. Great illustration overall fantastic video.
WW2 and the blitz, that one tube at one time was the greatest secret and had to travel to the States and the MIT Rad Lab as one bomb hit and it could have been the setback of the war.
excellent video as always!😍, you need to make a video of a turntable with that carousel motor, (like the video of the slider for video) the ones that I bought in amazon are not completely smooth and when recording the video small micro jumps are noticeable.
The clicky buttons are very good, also very overkill for the 5V i'm using one for. The click is very satisfying. Also they have both NO and NC, that's cool
Thanks for the video. I didn't know that thorium was used on magnetron cathodes. It will be necessary to disassemble and check the radioactivity in the Wilson chamber or with a radiometer.
Thoriated tungsten is a very common thing, you buy thoriated tungsten TIG welding electrodes cheap, and they go up to 4% thorium, so are well worth putting in the cloud chamber.
Ive taken a couple hundred microwaves complete to bare bones, and this is the most informative, scientific, and factual 13 minutes about any machine or device I have ever been witness to. I am well versed so I commend your quality of reverse engineering, photo shooting & editing, public speaking and i have a hunch English is a 2nd language yet you speak better than the people in my neighborhood. Make more. TVs. VCRs. Hard Drives. Vacuums. Water Heaters. Radiators and Air conditioners. You make Bill Nye look softer than melted butter! ;)
just about time. i plan to do thorough cleaning of my microwave oven. and just pike you said, i qlso afraid of the radioactive material. but now i know which part is dangerous. thanks to this video of yours sir
very well explanation thank you for your hard work but i wish you would explain more about why they go bad and why the microwave started to spark and burn the inside of the microwave box
I worked on radar systems since the mid-seventies in Marine aviation. I have had a basic understanding of magnetron operation all these years and even taught electronic theory as an instructor, but this was the clearest, most accurate description of what is truly happening, that I've ever heard. Thanks!
@@stujones3566 Same - really clear info on the LC circuit.
John, what is the power and frequency used in Marine radars ?
@@Mayosoftware Tesla level stuff man!
@@JohnNy-ni9np sus comment
@@JohnNy-ni9np...its adjustable for military purposes. Long range dissipation is very high. A so called horn focuses the beam. A ordinary sheet of aluminum foil can already protect 100% by reflection.
I was in tactical communications in the Army in the late 80's and early 90's and we used a 5 cavity tunable Klystron as our High Power Amplifier. All the basics are pretty much the same. You do a VERY good job of breaking this down and explaining this function. I really enjoyed this video. Thanks.
FINALLY. after about 20 videos, I find a good explanation of the cavity magnetron! Thank you. Whoever took the components & operation of a discrete LC circuit and recreated the effect in a solid lump of copper by just using geometry was a genius.....pure inspiration.
the Germans did
I was a US Navy electronics technician in the mid-60's so I feel I have a better-than-average understanding of the science. Your explanation of the principles behind the magetron are, by far, the best I've ever seen. I especially highlight your illustration of capacitive-magnetic resonance. You have done an excellent job!
Dont worry - an insulator of the RF output feeder is not made from beryllium oxide ceramic. Nobody, even Chinese, makes domestic equipment with it. This one is made from Al2O3 with a little manganese doping which defines its color. So yep, basically this is a technical ruby ceramic. Also you can do a simple test when in doubt of containing beryllium - just flash a 360-365 nm UV light on it: corundum ceramics will luminescence with deep red ruby-color and beryllium ceramic shows a weak purple luminescence.
BTW, if anybody interests, the kitchen oven magnetron is just one of the big family - in other magnetron types, like pulsed for radar, coax-type, relativistic MILO or spatial-harmonics mode, the construction and electric field patterns are much more complex but working principle is close the same.
Best description of how a cavity magnetron works I've ever seen.
One thing to point out though "This could melt you from the inside out without you even knowing"
You *will* feel burns from microwaves in the 2.4Ghz (yeah, microwave ovens use the same frequency as old WiFi) region, they vibrate water molecules so you will definitely notice the burning. Microwaves are used in crowd dispersion devices (higher frequencies, less penetration) because you can feel them and they *hurt.*
The high voltage is a hazard, but a microwave isn't going to cause burns much more serious than a 2000 watt IR heater, especially at a distance. A microwave oven exploits the fact that the waves bounce and are close to the magnetron.
If you turn it on outside the enclosure you're more likely to damage sensitive electronics as well as draw the wrath of whoever governs RF frequencies where you live than get badly burned.
Yeah I've seen a guy comment on a similar video, he thought the oven stopped working so he put his head inside to check something out and he described the feeling as getting very dizzy, but nothing more serious. And it's the brain we're talking about, so it's definitely not that dangerous.
And anyway it takes a while to get some heat to build up, with the brain thing it wouldn't be a surprise if the actual molecular vibration does something weird rather than heat alone.
In addition to the correct statements you and @Techalyzer have already made, microwaves also just don't penetrate that far. When cooking food, anything more than about 1" thick will heat much more slowly. For practical purposes, if you can arrange the food to reduce thickness, including putting an indentation in the middle of malleable solids like rice, mashed potatoes, etc., you can heat the food more evenly and quickly.
For humans, this means that yes, some potential for injury exists if one really just ignores the pain involved before things get hot enough, but it's unlikely organs deep in the body would be affected much if at all.
I wonder if is this going on in Ukraine. During the Bosnian war very expensive anti radar site missiles would get to blow up decoys made of ovens rigged to operate with the door open.
Probably the highest ratio of cost to kill ratio of any tech warfare kit.
@@echodelta9 Shortwave diathermy machines were used for similar purposes in WWII, though instead of disrupting radar seeking missiles they disrupted a radio beam intersect used by bombers.
IIRC it was called the battle of the beams.
Great video!!! You just taught more in 15 min than what I learned and understood out of a college introduction on Microwave Theory in the 80's!
Your content is so good! Haven't seen all, but I watch most of your clips and often times you inspire me to do more and to try my own projects ❤️
Thank you! I have seen multiple explanations how a magnetron works in textbooks with drawings, but it makes much more sense for me seeing the inside of it. Also your explanation was better than my 100€ physics textbrick. It finally makes sense.
The electrons alone won't cause any radiation, even when you spin them by the magnet. What makes the microwave energy is the combination of the electrons moving aronund the cavities, forming a kind of "electron whistle" (the theory is a bit more complicated, but on some aspects the electron movement becomes somewhat similar to what the air does in the regular whistle). The high voltage combined with the magnets is use to make the electrons to move along the cavity tops to form that whistle, without the magnetic field they would just fly straight into the cavities, so no whistle.
A good explanation.
Actually they do and the video explained that. Any electron that undergoes acceleration releases photons. He said the magnets were put there to make it "more efficient".
Actually I would be very curious to understand that "electron whistle". Would you have any links or explanation ?
it's about resonannnnnnnnce. RF is all about resonance, really. What frequencies and what proportions -- and especially geometry. The magnets provide a field for the electrons to surf against and curve into a spiral, it's together with the force of the electric field reacting against the uniform magnetic field that creates motion at a right-hand independent vector. The electric waves radiating out of the center would merely be attenuated by reflection by the LC tank of the copper cavity, but realistically I'd wonder if it would just cease to operate from damage overheating after a short time without the needed magnetic field to transform the radiated energy into EM waves with transmission capability.
Thanks for the explanation. This is truly incredible every day engineering that we take for granted.
I have always wanted to know how magnetrons work and this was incredibly comprehensive. Thank you
Do gigatrons work in similar fashion?
dude, standing o. Been watching your channel for a while and your visuals and explanation game went exponential recently like 3B1B or Steve Mould or ElectroBOOM level. Keep up the great work.
Newer microwave no longer use brillium oxide so you're perfectly safe but it's the ceramic dust that you should be more caution about
That was kind of an old microwave that's why I tought it could still have... Better avoid it :)
Any dust are dangerous in high volume, maybe he breeze only few micrograms or less anyway everyone will die
@@ELECTRONOOBS I think it’s safe as long as you not breaking the ceramic
Beryllia is very white; a pink tint generally indicates alumina (aluminium oxide) ceramic which is much safer to handle.
@@ELECTRONOOBS it would have to be one of the very, very early microwaves to have BeO (The old Raytheon Radarange for example)
I like this teardown. Subscribed!
It needs to be mentioned that the magnetron receives high voltage DC as well as a very low voltage AC from the transformer secondary coils.
One secondary coil puts out about 1400VAC, is rectified with a diode and doubled to 2800VDC as it charges and discharges the capacitor in phase. This is connected to the cathode of the magnetron through one of the filament connections.
The other secondary coil is a high current 3VAC and is responsible for heating the filament in the magnetron.
I learned about them very long time ago and I was not sure about the concept but now everything is clear thanks man.
I worked in a reprocessing plant for electron RF vac tubes. From a very small 1.5Kw to a huge 357lb (with water jacket) 3.2 Gw vacuum tube and all sorts in between. I learned a lot. How electrons are emitted and controlled by electromagnet oscillation. This video was very informative and not overly technical. Thanks for a job well done.
A warning about that few kV capasitor would be nice, since old ones might not be able to discharge themselfes on their own anymore (built-in resistor could burn out over time), so during disassembly it's always good to check by bridging the leads with some conductor with a good isolated grip/preferably on a stick.
Good general advice for any power supply, really.
For really high voltage stuff in the Navy, we had shorting probes and, in extreme cases, thick rubber gloves. I want to say protection up to around 30Kv with both.
Which reminds me of an actual maintenance check documented in the technical manual for an air search radar I worked on, that dated back to the 50's or so. It was called the "tinfoil test" and was a way to test the "crowbar" circuit that was supposed to shut down the radar's high voltage in the event of a short.
You would take a piece of foil and wrap it around the end of the copper rod of the shorting probe, fanning it out for a couple of inches. Then, you would glove up, open the cabinet to get access to the high voltage connection, connect the probe's ground clip, then bring that fanned out piece of foil, slowly, close to the HV connection. Before you make contact, it'll arc to the foil, burning a hole in it, until the crowbar kicks in and shuts it down. You then measure the size of the hole burnt in the foil. If the hole is too big, the crowbar was too slow, and it fails the test.
I got to be first in my class at school to do that test. Makes a rather startling pop, too. 🙂
I used to repair microwave ovens. I've stripped lots of them. The reality is that if you test the capacitor, the voltage is gone in seconds. It's all BS.
To test a magnetron , you measure the voltage at the terminals. If the magnetron is dead, you'll get maybe 2.2KV and if it's good and drawing current it will drop to about 1.9KV. Got to use a high voltage 1000 times probe in the meter to measure
@@brolinofvandar super cool! Thank you for this share
⚡Bang! 💥🤣
What a brilliant video! After just replacing a faulty magnetron in my microwave oven I was interested to find out what is inside one and your video explained it perfectly with a great explanation and clear animations. Thanks! I had already pulled the faulty unit apart to salvage the magnets and was aware of not breaking the ceramic insulators, but hadn't gone so far as dremelling the copper anode. I have subscribed.
My microwave is an inverter model to vary output power and doesn't seem to have the large capacitor. There are smaller ones on the inverter PCB. It would be interesting to see a video on how inverter microwave ovens work. Thanks again.
Thank you for doing this video Andrei. Microwaves are something I've been curious about for some time. I really enjoy the animations you put into your explanations. I'm looking forward to the next video on this topic.
Nog een nederlander *G E K O L O N I S E E R D*
You are genius sir! The video presentations, your descriptions, animations, all of it, learning a ton from you 👍✨ very grateful
one of the best videos actually explaining how a microwave funcitons! great stuff
Excellent tutorial on how it works! Thanks! This if by far the best detailed illustrated explanation of how the magnetron works!
This is the best description of a magnetron I've ever seen. Great video! You should do one on a 555 timer if you haven't already. I'd love to watch that.
Wow, this is the best explanation I have ever heard of how a microwave oven and magnetron works.
Great video! One mistake I noticed though was in the explanation of LC circuit oscillation. The mistake was the presence of a magnetic field in the inductor when no current was flowing, at 6:59 and other moments, and reasoning that the collapse of the magnetic field at 7:05 is what resets the polarity of the capacitor. Instead, what actually happens is the magnetic field would begin to collapse once the voltage across the capacitor is 0V and the current is maximum, at about 6:54 in your animation. Only THEN would the magnetic field have collapsed, and the inductor would oppositely charge the capacitor to how it is seen at 6:59. I love EM, so I couldn't let this little inaccuracy slide ;) Cheers!
hahahahah thank you. The presence of a "static magnetic field" is actually just a pause in the animation while explaining. In real life it would be fast as you say, the field collapsing after the voltage passes the threshold.
@@ELECTRONOOBS You're welcome! Just wanted to clarify that an inductor's magnetic field will only collapse in this circuit when the voltage across the capacitor is zero.
I believe you got something wrong there, as the magnetic field is proportional to the current in the inductor, so the magnetic field has its maximum amplitude when the capacitor voltage is zero. Thinking if it in another way: Energy must be conserved, so when theres no cahrge in the capacitor (0 V) The energy must all be stored in the magnetic field
It fulfills my gap of knowledge of microwave theoretically against practically . Thank you very much .
I have done years of magnetron research but have never until now seen a presentation suitable for an introductory physics or engineering course. Great job!
Hai i need help regarding usage of magnetron for waste management, plz send ur mail id
@@shanthalakshmik6884 Stop lying, there is no use for a magnetron in waste management. Fucking scammer.
Amazingly informative video. I learned so much. Also learned I should handle those insulators with more care 😬. Ive taken apart a number of microwaves but never knew what it looked like inside the copper high voltage diode, really interesting way to use induction.
While studying radio, I found Inductors and Capacitors are kind of opposites.
Just a great video with clear-cut explanations and graphics to show how magnetrons work. Thanks so much!
What a great teardown!
I've long wondered about the mysterious workings of that magic box in the kitchen.
I've always been told not to tear one of those apart for fun. Now I know what to do and not do.
You earned the subscription, thanks for that great presentation
You long wondered how copper wire and magnets work? The schools suck today?
I have watched thousands of videos on this subject and none and I mean it! none explains it better than you. You are the true king of random🤴
I always wondered how mangnetrons worked. Thank u for creating such a great content so that any newbie could understand how things works. Now I wonder how genius are those who designed this😇
Very good tutorial, I was entranced but never bored!
Fascinating stuff. I think your visualisations are top-notch!
I know well I've watched other videos before and got lost , this explains it in terms even I can understand!! Brilliantly explained and thanks!
Very good presentation.
I was trained at Varian Assoc. in my earlier years, designing and making both magnetrons and klystrons.
It was all about copper, powerful electromagnets, EHT, shf, amps and heat. Our klystrons were used for both radar and TV transmitters and consumed many 100's KW of mean power. The ones I worked on not only emitted microwaves but incidently X-rays which had to checked for safety. The vacuums were typically down to 10^-12 torr if I remember correctly provided by ion pumps.
Cant go into too much details (frequencies, output power etc) for obvious reasons but I believe most of this technology has moved over to Solid State!
Thank you for your comment. What did you have to learn to start doing microwave tech?
@@cherylm2C6671 Quite a lot, I studied electromagnetism (Maxwell) and the maths in my own time, linear algebra and basic electrical theory. Our company was also working on the new X-Ray Tomography machines just coming into production.
I worked in the section designing and making the cavities, so had to learn to use machine tools as well, to very high tolerances I may add. The smallest klystrons were used by jet aircraft in the nose cones, these were much higher frequencies (X band) but much less powerful.
@@tomctutor Thank you for your reply. I look forward to learning more about magnetron applications. Cookbooks now, theory eventually.
The animations that you created to show microwave propagation was perfect at helping me to understand what's happening 'inside the box'.
That's why you want to spin what you're cooking so the waves don't heat up one spot.
Thanks for this video explaining how the cavity magnetron works. I have made a video showing how to troubleshoot simpler microwave ovens similar to yours. I simply explained that the transformer, diode, and capacitor can be tested easily with common meters and tools; and that if you confirm they are all good but there is still no heating, the magnetron can be suspect by process of elimination. My mom still has her 1988 year Sharp microwave. Its original magnetron lasted until 2020. Very well made product! I was able to get a used magnetron from eBay for a few dollars and get it going again without problems.
Thanks again for your good explanation!
Thank you for your comment. I'll look for that video.
@@cherylm2C6671
You're welcome. I'll post a link to the video in the next comment. If you only see one comment then it means UA-cam is blocking the link.
@@cherylm2C6671
Microwave diagnostic video: ua-cam.com/video/v8O3S9H4l_c/v-deo.html
This is such a basic and simple to understand explanation. Thank for this excellent video. May God Bless you. Steven. U.K.
Awesome demonstration, thanks! I learned about this stuff twenty years ago for radar theory. Perhaps a lesson on cyclotrons next.
You are amazing and very knowledgable in deed, thank you so much for your time, knowledge, wisdom and best efforts!
Thanks for all the safety tips and discharging the capacitors are important also, which can be deadly if touched before properly discharged, thanks for all the details, the transformer can be used to make a spot welder for small projects
I thought I knew how they work! Turns out different. Very interesting great information and format. Another sub here.
Cant wait for part 2 .. where you explain more in depth about microwaves .. and how "propagation" happens and why!! 🙏
Though video was pretty good, i would like to mention that ''the metal sheath'' you mentioned on the beginning of the video is actually made of mica, and it is interchangeable. If it gets pounced, it can be replaced , and the microwave oven is good as new.
Thank you for your comment! Cleaning the interior often is a good insurance. Fat splatter gets hot enough to damage the protective mica.
@@cherylm2C6671 I used a plastic film on one of my ovens and it worked for many years with no visible damage. I think that mica is used just as a "worst case scenario", the area doesn't usually get very hot during normal operation.
@@techalyzer I will try that! Thank you for your suggestion! That will make cleaning easier than pushing on that mica plate. break. Fats (or bits of exploded egg) kept away from the magnetron.
What does ‘pounced’ mean?
@@2Sorts i mean if a hole appears, as shown in the video
Best I’ve ever seen on the subject. Well done!
Very interesting. You could reuse from 8:00 to 14:00 in a video comparing the magnetron with how a Radar Vacuum tube achieves frequencies and speculate why we do not use tubes in microwaves ( excluding manufacturing as when commercial microwaves started being made, there were vacuum tube manufacturers that could do it ).
Simple reason is cost and efficiency, magnetrons are over 50% effective at generating microwaves, and need no excitation at all, where transmitter tubes need both an exciter stage to drive them, and also filters on the output, plus the typical efficiencies of around 30% is a big drawback, and also the volume they need. Magnetron combines self exciting, and built in filtering cavity filters in it's design, so it is a single part.
What do you mean by "Radar vacuum tube"? Magnetrons _are_ vacuum tubes. Indeed, they are used for certain types of RADAR too. Klystrons aren't altogether too dissimilar in working principle either but they're specifically set up to be able to amplify a signal, whereas a cavity magnetron can only really act as a local oscillator. Handheld RADAR guns use solid state devices (Gunn diodes) and there are now power FET devices that can operate well into the mw band, but when theres no need for a high fidelity, low noise amplifier and all you need is raw RF energy it's pretty tough to beat the humble cavity magnetron.
@@whatelseison8970 The ORIGINAL vacuum tubes used for RADAR had a micro disc inside as the resonator with specific gaps on the inner circumference for the RADAR frequency instead of the size of copper chunk inside a microwave oven. It appears if you increase the size, triple the wattage you can achieve the same frequencies and higher without being in a vacuum.
Thank you for your comment. A radio science newbie is always looking for analog applications. There is still plenty of work for vacuum tube in the industry.
That magnetron is a vacuum tube till you cut it open.
Good video and thank you so much for not having background music or irritating sound effects!!!
Very nice video. Been working with microwave sintering and a better understanding of the magnetron / teardown is useful 🍻
Very nice video! You are the only one explaining it properly...So it's based on an LC oscilator.. Now it makes sense.
First time I actually understood the process being explained. Well done.
Finally someone explains magnetron in a way that everyone can understand!
Wow - this went deep fast. I had no idea that is how they worked. Whoever thought of this was a genius.
Nicely explained thanks, I've never seen the inside of a magnetron before.
Theoretically microwaves don't come from the hole of the antenna, but really from the insulator, 8:55 those are actually the Heater inputs, anode is grounded on a magnetron, btw nice video
Thanks for the content. I am very interesting how magnetron and whole oven works.
Hey, this was excellent and informative. Great job and thank you
"Dr. Who and the Rise of the Magnetrons"? I'D BUY THAT FOR A DOLLAR!
Excellent presentation - thank you. Remember - NO stupid risks, please.
Thank you so much for your video! Your video is the best I have seen on the internet. I will visit again. This is a better explanation and I can take notes and anticipate doing something with this- I'd better thank you!
Perfectly timed :) please also cover TWT, Relfex klystron and microwave diodes if possible
Back in the 70's, at ET "A" school in the Navy, I taught these things. Something like this video would have been nice back then. I made do with drawing a cross section on a chalkboard and trying to describe the electron flow that way. Animation is so much nicer. Our animation was Army films from back when radar was invented, mostly cartoons with sgts yelling and hearing echos.
I always found the reflex klystron intriguing, with its re-entrant cavity. The visualization reminded of a popcorn popper, electrons flying up through the cavity, seeing the repeller plate, and reversing back to the cavity. One of the weirder devices, but kind of fun to teach.
TWTs, on the other hand. We really only touched on them, and I never worked on them. Taught a brief segment on them, can't say as I really understood them that well, myself. I can say, however, I can remember having to change how we referred to them while I was there. The change happened as we started getting women coming through the school. Before, when we talked about TWTs, they were amplifying tubes. After, we had to refer to them as intensifying tubes. Because we used an acronym to refer to them, and I'll just leave it at that.
@@brolinofvandar Tit for Tat. 😲🤣
@@jlucasound Don't forget the 'W'.... 😀
@@brolinofvandar Known as Twits in my SatCom days, Did all the theory during my apprenticeship training, now long forgotten. Still makes me shudder working on water cooled klystrons, power off of course, but nevertheless, had to be done.
The safest, for me most useful, component from a scrapped microwave oven is the timer. I kept on forgetting my solder iron, leaving it on overnight until I connected via the timer. I prolly will do an upload to show how it was done. Love these teardowns! Thanks. 🙂
Going to check it out now :)
Years ago i took the display/keypad/controller assembly off an old microwave oven and attached a power cord to it and hung it on the wall in the garage. Makes a great wall clock with count down timer and beeper all built in. Great conversation piece.
Your explenatiion is an art piece. Awesome job.
The 2100 volts capacitor filters de AC current from the transformer.
The anode needs at least 2kv to work. This high voltage comes from the transformer working as elevator from 230v.
Very good explanation. Thanks.
I love the way microwaves heat food , but this blew my mind even more! VERY good video of yours.
seriously! i need to turn on the alerts. i appreciate the level of detail you go into, much more interesting than when it gets glossed over
@@cabasse_music The more you go in detail the more interesting it becomes!
around 13:22 , you said that the microwave transformer generates around 300V AC! i know its just a typo and in the captions it says correctly as 3000V but to just let you know, i pointed this out. Nice video man as always, hats off to you! keep making such informative content🔥🔥🔥
The correct is 3000V. I've read wrong the script, sorry :)
@@ELECTRONOOBS They are basically an electric chair in a box.
@@ELECTRONOOBS It's 2KV
@@user-lp3cf5yn5b 😂 kill ya volts
Great description and graphics. Thank you.
Nice video, well done, thank you for sharing the knowledge with us :)
I worked at a microwave plant in the 90's and would go through the "dud" pallets of magnetrons getting tossed into the scrap dumpster to get all the ceramic magnets out of them. NOW I know how those crazy things work. Thank you!
You threw out copper like that as scrap?
@Star Gazer It's like 95% aluminum with very little copper but im sure it got separated at the scrap yard by some means.
Excellent description. Thanks!
0:13 White text over a white background, which is perfect. Congratulations for the enormous amount of editing skills. Wait...
Excellent video. I'd like to add a suggestion: When explaining tne 'capacitor' (formed by a sudden carved section on the copper rod), the electrons closer to the travelling one should be presentend getting away from it... creating the depleted area.
oh, nice addition to the Utopia soundtrack playlist. What a banger!
This was very well presented ! Thank You !
Excellent presentation!
Much appreciated 👍
3:55 it doesn't actually shoot out of that hole like a gun. It radiates around the ring almost like an omnidirectional antenna. thus why waveguides are needed. Great illustration overall fantastic video.
I've torn apart 15-20 microwaves for copper salvage and I didn't know that this, knowledge helps avoid slow painful death. ❤
This was very good and informative. Thanks!
I feel in love with the turn table motor the first time I took a microwave apart
How did someone dream that up. We're lucky to have these incredible inventions at our disposal just so we can make some popcorn quickly.
As long as it's just the bare popcorn! The other ingredients have interesting properties (and do NOT taste nice).
WW2 and the blitz, that one tube at one time was the greatest secret and had to travel to the States and the MIT Rad Lab as one bomb hit and it could have been the setback of the war.
excellent video as always!😍, you need to make a video of a turntable with that carousel motor, (like the video of the slider for video) the ones that I bought in amazon are not completely smooth and when recording the video small micro jumps are noticeable.
Excellent video, so clear. You have talent. Thank you.
Simple explanation easily understood
this video is totally underappreciated
This is something I always wanted to do but was always afraid touch thank you for satisfying my curiosity
The clicky buttons are very good, also very overkill for the 5V i'm using one for. The click is very satisfying. Also they have both NO and NC, that's cool
Nicely explained. Projectants of magnethrone were a genious!
This is the best presentation I have seen so far.. . Good. Very, very good...
Exactly what i was missing, thank you!!!
Thanks for the video. I didn't know that thorium was used on magnetron cathodes. It will be necessary to disassemble and check the radioactivity in the Wilson chamber or with a radiometer.
Thoriated tungsten is a very common thing, you buy thoriated tungsten TIG welding electrodes cheap, and they go up to 4% thorium, so are well worth putting in the cloud chamber.
@@SeanBZA I know about TIG welding.
That was fascinating to see how the magnetron works! thankyou!
Interesting indeed. You're a good teacher, I understood everything you said.👍
I really appreciate your works, Sir.
Great explanation thanks.
I am gobsmacked by how these ovens, with all that gear, can be sold for $35
Thanks a lot sir for these clearest explanations I ever had. Regards.
Ive taken a couple hundred microwaves complete to bare bones, and this is the most informative, scientific, and factual 13 minutes about any machine or device I have ever been witness to. I am well versed so I commend your quality of reverse engineering, photo shooting & editing, public speaking and i have a hunch English is a 2nd language yet you speak better than the people in my neighborhood. Make more. TVs. VCRs. Hard Drives. Vacuums. Water Heaters. Radiators and Air conditioners. You make Bill Nye look softer than melted butter! ;)
Bill Nye is a hack and a shill for the New World Order. Paid actor.
just about time. i plan to do thorough cleaning of my microwave oven. and just pike you said, i qlso afraid of the radioactive material. but now i know which part is dangerous. thanks to this video of yours sir
Come on electronoobs deserves more than 500k subs
Awesome video! Love your explanations
very well explanation thank you for your hard work but i wish you would explain more about why they go bad and why the microwave started to spark and burn the inside of the microwave box
Thanks for your tutorial,🙏🙏🙏🙏🙏