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Make a Microwave oven on a small-scale


Dazza
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I would like to understand how a microwave oven works. I would like to experiment with microwave's, to be used in conjunction with electrolysis for producing hydrogen. From what I understand on how microwave ovens work, by vibrating molecules to create heat. I think it may be possible to reduce the energy needed to produce hydrogen, by using microwave's to help loosen the bond of the molecules, and resulting in less power needed for the process of electrolysis. I think it's worth looking into, even if it doesn't reduce the power needed for producing hydrogen by much.

And if I do use microwave's with my experiments. I understand there is a safety issue, adequate shielding will be needed, as well as using microwave detector devices to ensure I contained the dangerous radiation.

Is there any microwave experts out there ???.

Thank you for any help :).

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:)dazza ive posted the circuit for the microwave oven to the topic of emp i think it was if you cant find it ill redo it again for you ive dismantled microwave ovens and still got the magnetron and high voltage capacitor to. and transformer, there is a site showing the microwave oven details to

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By the looks of things I need a magnetron that is a third of the size, or maybe smaller. Has anyone invented a shrinking Ray yet :o.

Does anyone know of a device, that contains a small magnetron. Or maybe another way it could be done.

ante, have ya got any old radar equipment in the backroom at work ;D ;D.
Thanks for the links ante, good stuff :).

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Ante, I am trying to reason with the possibility of making my own magnetron :o, can you see any problems with a magnetron maintaining its same function, if I was to replicate it exactly to a small-scale, I'm just considering the possibility 8).

What I really need to know at this stage is what size magnetron do I need, it is a very small area that I need the microwave's to affect, it would only need to be an area of say half a glass of water, and it can be much less than that with careful designing of the reactor, which I have spent a lot of time on designing and is looking very promising 8).

So in knowing the area that I need the microwave to affect, I then need to try to work out what size magnetron I need, and then the power required for that magnetron. It's the resonating affect of microwaves on molecules that I am wanting, not the heat generated from the friction of the molecules being vibrated rapidly, a good heat exchange system will be important.

I think using a magnetron from a microwave for this application, would be like building a dog kennel the size of your house ;D ;D.

Some questions that I need to find answers to.

The size magnetron I need to produce the resonating affect on the required area.
The amount of resonating affect on the molecules needed, to increase the process of electrolysis.
The optimum frequency of the microwave's. 2.45 GHz is what manufacturers of microwaves ovens have chosen and they would no more than me, but my invention is not a microwave oven so you never know.
How much power required for this process, of course there will be other factors that will need to be known first. Does the microwaves increase the process of electrolysis, enough that efficiency is not lost but increased, I think this can only be known by trying.
A microwave is not very efficient, in respect to what I want to use it for, so what is the best efficiency I can expect from a microwave/magnetron.

Yes magnetrons in microwave ovens are cheap because their mass produced, do you have any idea on what you would expect to pay for a small magnetron, knew or second-hand. ???
I asked my Swedish neighbour about magnetrons, he told me he through two small perfectly good magnetrons away before he moved here. Just my luck :'(, I told him he should have known I would want them, even though he didn't know me then ;D.

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Ante, I was thinking that a small magnetron would be a little less risky and easier to manage, then a larger one from a microwave oven. If I was to use a microwave oven/magnetron, it would be very difficult to use for experimenting with, because it can only be turned on at full power. I can't let the water boil, it has to be kept cool with a heat exchange. Large magnetron affecting a small volume of water = very fast reaction, maximum resonating effect, water heats and boils quickly, very difficult to maintain temperature to prevent boiling.
Small magnetron affecting the same volume of water = small amount of resonating effect, water heats slowly, not to difficult to maintain temperature with heat exchange,

I am really not sure on how I can go about conducting experiments using a microwave oven, or a magnetron from it, a microwave puts out such a high output, I would have to use a large volume of water, to try to mimic the way that it will work in the reactor. I would have to try to find a way to contain and measure the volume of hydrogenbeing produced. This would be a very large device for experimenting with. Maybe a large plastic sealable drum , 10 litres and direct the microwaves from the bottom upwards, then place the electrodes towards the bottom and then I would have to shield the whole thing. I could use a tube coming out of the top of the drum and collect the hydrogen and oxygen being produced into another drum filled with water, the hydrogen and oxygen will displace the water then the oxygen and hydrogen can be measured. This might work, I would be able to position the electrodes hire or lower in the drum, the microwaves should be stronger at the bottom and weaker at the top. Well this doesn't seem so difficult now. But "WOW" this device would give the perfect opportunity for a disaster. High-voltage, water, explosive gases, microwaves, what a cocktail :o. I may become famous after all, the first person to get electrocuted, burnt and blown up, all in one go. ;D ;D ;D

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This is a change of pace ante, and for a change I do have some answers. How I came about to understand how microwave ovens work. It was many years ago and I was working as a labourer for a small electrical company for about three months, probably the most interesting and exciting job I have ever had, they also had a small electronic repair shop which had their first microwave oven come in for repair. There electronic technician had left some months earlier and they had employed a young electronic enthusiast until they could find someone qualified. As an interesting point, he was completely illiterate and he could outperform any electronic technician they new. Very encouraging for me ante. So they could not let their technician repair it, too dangerous and they were already taking a big risk letting him repair other equipment. One of the electricians had taken an interest on how microwaves worked. So it was the task of the qualified electrician and the electronic technician to fix it, and I was lucky enough to be able to offside, there was quite a lengthy discussion on how microwaves worked. So now that I board you ante ::), I will try to explain what I learned from them on how microwave ovens work.

The frequency of the microwave was chosen because it could penetrate matter to a certain degree. If the frequency was chosen to high or to low the microwaves would either pass through matter or penetrate very little, so a frequency somewhere in between that could penetrate to roughly a central point, of the type of matter that will be penetrated. which of course is different types of food water etc, now as I am to understand, it doesn't really matter the amount of power you apply to the frequency being radiated, within reason. The penetrating effect will be virtually the same. So cause and effect, the microwaves energy have penetrated matter to appoint where they can go no further. The molecules absorbed the energy from the microwaves causing them to vibrate, the friction of the molecules vibrating or rubbing against each other generating heat. so if you want a greater effect that is generate more heat, you apply more power to the same frequency. The same principle would apply to radar, the frequency is chosen to be able to penetrate matter reasonably well with as little effect on the molecules as possible, which in this case is the molecules/matter in the atmosphere, and also not to be able to penetrate other types of matter such as aircraft, in this case the signal will bounce back to be detected. So for radar to be capable of detecting aircraft over a great distances, you would need to apply more power to the chosen microwave frequency, because of the loss of energy absorbed by the matter/molecules in the atmosphere. Submarines also use radar and the same principle applies, although if they want to detect other submarines over a great distance, they would need an enormous amount of power due to the loss of microwave energy penetrating through the water.

Hopefully I'm not too far off the mark ;D.

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Dazza,
Interesting story! Well it all makes sense to me, so it must be correct! ;D But I was wondering about the waves influence on the electrolysis in the reactor. Will just a little rubbing of the molecules improve the amount of hydrogen produced or the speed of the process or both?

Trigger,
You may have a point there!

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Ante, those questions are something I think I will only know, by research and experimenting 8). Sometimes the most unlikely solution to a problem, can sometimes be the best solution. Or even lead to new technology/discoveries.

You would expect that maximum resonating effect upon the water molecule, at its ideal frequency would yield the best results. Maybe I could even look at experimenting with electromagnetic fields, although I cannot see what affect it would have, if any.

I sure am in for a lot of trial and error, to get this system right ;D.

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I don't know about warning the Swede, but discussing with him how we can ensure his extensive range of high quality home-made alcoholic beverages, can be kept safe and sound, would be a priority :o.

Safety is always at the top of my list, especially when dealing with things I am unfamiliar with.

Ante, tips on safety are always welcome, no matter how trivial it may seem.

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  • 2 months later...

To the issue of making the magnetron in question smaller:
You're dealing with physically and electrically resonant structures. If you change the proportionate size of the magnetron cavaties, you'll be--in my understanding of the matter--increasing the microwave frequency of the overall design. It's likely that dertain driving components will have to be changed commensurately.

It looks like a full re-work, from where I'm sitting.

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Thanks for your reply Enigmaone :),

I was hoping, but didn't think it would be as simple as scaling down a magnetron :(.

Going by what you have said, I think it would be a task far greater than I could hope to achieve.

Maybe it would be a better option, to scale up my project to suit a standard microwave magnetron, for experimentation.

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A low power microwave generator, you could build a 2.45GHz ocillator and connect it's output to a RF power amplifier.

This solution is easier said than done, as building a stable 2.45GHz ocillator is quite tricky, you might be able to do it by using a PLL to multiply up a crystal ocillator. The only way to get power microwave amplifiers from solid state devices is to use HEMTs orGaAs MOSFETS in class E configuration.

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Hi Alum,EnigmaOne,

I'm wanting to experiment with microwaves and the resonating affect upon water molecules, to try to increase the production of hydrogen in conjunction with electrolysis.

I don't need a great amount of microwave energy for experimenting. I am new to Electronics and the simplest way for me to produce microwave energy was by using a magnetron, which I am a little reluctant to use because of the great amount of microwave energy produced that I do not need for experimenting with.

I would greatly appreciate some guidance/examples on ways of producing microwave energy. I'm afraid the methods that use suggested, is a bit over my head I need some examples to learn/understand from :).

Also it would be very useful to be able to vary the frequency for experimenting, that was another downside of using a magnetron, although I've got no idea how I can accurately measure the frequency, I don't have much in the way of test equipment :(.


The link below is basically where I started with this project.

http://www.electronics-lab.com/forum/index.php?board=28;action=display;threadid=1321

Thank you for your reply.

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Is the microwave frequency equal to the resonant frequency of water?? When the microwave applied, the water molecule will vibrate more fiercely?? and finally generate heat??

anyone can confirm this??



No the lowest resonance of water is around 28GHz


This is a change of pace ante, and for a change I do have some answers. How I came about to understand how microwave ovens work. It was many years ago and I was working as a labourer for a small electrical company for about three months, probably the most interesting and exciting job I have ever had, they also had a small electronic repair shop which had their first microwave oven come in for repair. There electronic technician had left some months earlier and they had employed a young electronic enthusiast until they could find someone qualified. As an interesting point, he was completely illiterate and he could outperform any electronic technician they new. Very encouraging for me ante. So they could not let their technician repair it, too dangerous and they were already taking a big risk letting him repair other equipment. One of the electricians had taken an interest on how microwaves worked. So it was the task of the qualified electrician and the electronic technician to fix it, and I was lucky enough to be able to offside, there was quite a lengthy discussion on how microwaves worked. So now that I board you ante ::), I will try to explain what I learned from them on how microwave ovens work.

The frequency of the microwave was chosen because it could penetrate matter to a certain degree. If the frequency was chosen to high or to low the microwaves would either pass through matter or penetrate very little, so a frequency somewhere in between that could penetrate to roughly a central point, of the type of matter that will be penetrated. which of course is different types of food water etc, now as I am to understand, it doesn't really matter the amount of power you apply to the frequency being radiated, within reason. The penetrating effect will be virtually the same. So cause and effect, the microwaves energy have penetrated matter to appoint where they can go no further. The molecules absorbed the energy from the microwaves causing them to vibrate, the friction of the molecules vibrating or rubbing against each other generating heat. so if you want a greater effect that is generate more heat, you apply more power to the same frequency. The same principle would apply to radar, the frequency is chosen to be able to penetrate matter reasonably well with as little effect on the molecules as possible, which in this case is the molecules/matter in the atmosphere, and also not to be able to penetrate other types of matter such as aircraft, in this case the signal will bounce back to be detected. So for radar to be capable of detecting aircraft over a great distances, you would need to apply more power to the chosen microwave frequency, because of the loss of energy absorbed by the matter/molecules in the atmosphere. Submarines also use radar and the same principle applies, although if they want to detect other submarines over a great distance, they would need an enormous amount of power due to the loss of microwave energy penetrating through the water.

Hopefully I'm not too far off the mark ;D.


As you said 2.45GHz was chosen because it has the right level of penetration, 28GHz would be absorbed right at the surface.

I doubt submarines use radar underwater, as far as I'm aware they use sonar and not radar. Low frequency radio waves can travel great distances through salt water but microwaves get absorbed within a few meters. Low frequencies are useless for radar because the wavelength would be much longer than the boats and submarines you want to detect, VLF radio is used for communication with submarines though.


Ante, those questions are something I think I will only know, by research and experimenting 8). Sometimes the most unlikely solution to a problem, can sometimes be the best solution. Or even lead to new technology/discoveries.

You would expect that maximum resonating effect upon the water molecule, at its ideal frequency would yield the best results. Maybe I could even look at experimenting with electromagnetic fields, although I cannot see what affect it would have, if any.

I sure am in for a lot of trial and error, to get this system right ;D.


Microwaves mostly heat water by causing the molecules to vibrate but they also induce electrical currents and these also cause heating. These currents might help with the electrolysis but I doubt it as they're AC and the negative cycles would cancel the positive cycles. I can't see how microwaves do anything else but heat water, if you want to increase the efficiency of hydrogen production then why don't you just add salt to the water, you will also produce chlorine & sodium hydroxide.

Building microwave oscillators is difficult but there is lots of information available on the Internet, you want to vary the frequency so a Voltage Controlled Oscillator is probably the best solution as variable capacitors and inductors won't work at microwave frequencies.

You might be able to buy a single chip microwave VCO then you could just connect it to a pre-built power amplifier module.

Also I know it sounds silly but have you tried running a microwave of a VARIAC, you might be able to reduce the voltage and lower the power.
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