I've recovered about 30 microwave ovens roadside when doing "asset recovery sweeps" in my neighborhood, a fair number of them only needed one of the 3 safety interlock snap action switches replaced to become 100% functional again- people just don't fix anymore, they simply replace.
People are to scared to fix, as insurance will use any excuse to deny your claim. Oh you repaired the microwave well that clearly cased the heater in the other room to explode, claim denied!!
I hear ya, I have 7 large flat screen TV's in my living room at the moment, I fixed one with a couple capacitors, a different one still has the thin clear plastic protector film on the plastic case. It looks as if it never even got dusty once. They didn't have it long, and she dropped a plastic cup, and it bumped the screen. (not very hard she said) The screen turned instantly, completely black......hmmm.... its a 62" Vizio Good Luck with BeachsideHanks Microwave Oven Sales and Service :)
A couple of pointers you may wish to try on the coil side. 1. Get a ceramic crucible, the energy will be acting on the metal you are melting and not the steel crucible making it more efficient 2. wrap the coil with a thermal blanket (you can easily find thermal shielding tape used on high temp exhausts) to protect your coil and avoid shorts
@@brianmurphy9112 ahhh... no both ferrous and non-ferrous metals can be heated by induction. Look up "eddy currents", these are produced in the material by the rapidly changing magnetic currents around the material, it only needs to be conductive.
I think that a poor idea because at a certain temperature metal is no longer magnetic. That's why you can only see glowing metal parts in these coils. You need the crucible to have a higher temperature than the metal you wish to melt and you can't do that with ceramic(non-magnetic materials). Also, insulating the coil raises its temperature so you're negating the water cooling.
A small suggestion: it's best to fill the coils from the bottom with the drain from the top. This avoids any chance of air bubbles inside the coil, which of course won't contribute to cooling. Having the water tank raised as you have is good, as this will force water by gravity from the bottom to the top of the coils with no problem.
With your glass, of it is heated evenly it will not break. It is when you get a colder spot that the thermal expansion varies and different tensions in the glass will cause it to shatter. Having said that I did expect it to break at the base due to the different thickness of the base! Well done and I'll be keeping an eye out for an induction microwave, you are thoroughly worth subscribing to! 👍
Also glass gets more flexible and soft when heated up, compensating for the stress. It could have broken when cooling down though. Well, let's not paint the devil on the wall. The experiment went well.
right on! Hot plates break regular glass all the time because of uneven heating and thermal expansion. Use Pyrex, not as vulnerable - though it is spectacular when it does blow up.
@@flashpointrecycling Yes indeed, I had a Pyrex jug go on me in the microwave for some reason (it may have had a small chip/crack) and it was explosive!
LuckyGen, you are a master fabricator and inventor. I always enjoy your videos and the stuff that you accomplish because no one ever told you that you could not do it, so you just did it. The glass did not shatter because you did not thermally SHOCK it. It heated up slowly as the crucible heated up. Glass, depending, starts to flow around 2000F, ever see a 'hot shop' for glass work, very high temps. What you REALLY want to do is take a clay style or type crucible and wrap it in fluffly white aluminasilica high temp insulation, 1/2" should work. Put that inside a little larger diameter induction coil and then place the metal inside the CLAY crucible that you want to melt. The clay won't heat up from the induction field. Right now you are heating the 'pipe' and that heats the metal and melts it. If you use clay and INSULATE IT then the energy will melt the metal in the crucible and melt it even faster. If you can prevent the HEAT of the melt LEAVING the crucible by 1: radiation 2: conduction and 3: convection then you can EASILY melt stainless steel in the crucible. There is no limit to the upper temp. The only limit is the higher the temp the higher the delta T and thus the higher the heat transfer to the outside world. If you did not loose heat you could go to a million F....but at some time the heat loss will equal the heat input in and you won't go any hotter. You can't use a graphite crucible because that will be the same as the thin wall iron tube you used. Graphite conducts electricity. I'd suggest experimenting with clay. In fact, I'd LOVE to see a video from you on making a clay crucible. "fire clay" can easily hold molten steel, its what they use in the foundry that is still in the Pittsburgh area, (Braddock PA). All steel making cupolas use fireclay.
I was thinking that either way there will be heat losses using a steel crucible or a clay crucible. A clay crucible would take a lot of heat from the metal as it heats up. This is why I made a gap between the coil and the steel crucible so I could slip a thin piece of ceramic fiber to slow down the heat loss. I tried to make crucibles years ago and they were all failures. I think it is easier to buy crucibles than to make them yourself.
This foundry project is pretty cool, but I like blacksmithing and there are days when we can't burn coal. I think this would be a great heater for knife making.
If you're asking because you want to do it yourself and don't know how, it would probably be a manslaughter charge for anyone who gives you instructions. You only need a very basic understanding of the relevant physical laws and experience with electronics (and electricity) to be able to work this out (and improve on it). High voltage experiments like this are not where you should start learning, because if you make a tiny mistake, you die.
THE GLASS There are two reasons any object might break or melt in an induction heating device. 1. The molecular movement caused by the induction device and 2. The secondary temperature generated by the object being heated. First the induction device only resonates the atoms of metals. The glass atoms are not affected. The secondary contact heat from the coil was sufficiently evenly distributed on the structure of the glass to cause expansion of the area of glass to induce a crack.
It appears to me that what you measured with the meter is that your single-turn secondary winding was producing 30Volts AC. The meter was set to its AC voltage position, rather than the frequency (Hz) position so it was not measuring 30kHz.
Have a look at the video again and see that my meter has a blue Hz button. If I select AC or DC mode and press the blue Hz button it will measure frequency. Also have a closer look at readout, it shows 32.00k.
@@luckygen1001 Sorry, my mistake. The blue button isn't really legible in the video, and there is a Hz setting on the selector switch, which led to my error.
I'm pretty sure this gentleman knows how to set his meter to read frequency if he is able to successfully modify a microwave inverter, without it going bang.
@@luckygen1001 Hmmm. According to the QM1535 manual, it should be set to Hz, not Volts, to read frequency. The blue button selects between duty cycle and frequency measurement when the meter is set to Hz. Maybe you have discovered an undocumented feature of the meter.
The glass heated uniformly enough. When one part of a glass object gets heated while the other part remains cooler it gets to a point that the hotter part expands more than the cooler part causing internal molecular stress that leads to fractures in the glass
Luckygen have you checked the frequency of the inverter when it is driving your work coil? The reason I ask is because I noticed that when I checked the PSU in my spare microwave, the frequency is below 30 kilo Htz when it first starts up. Presumably the lower frequency operation occurs before the magnetron emitter heats up and the magnetron draws power. That variation in frequency suggests that the PSU does not operate at a fixed frequency. Rather, the ramping up in frequency would be consistent with what would happen if the PSU control circuitry cuts the magnetisation current off when it reaches a particular value in the cycle. If that is the way it behaves, the frequency would go up if your setup is making the PSU work harder than it normally does when driving the magnetron, Hence, my question about what is the frequency when driving your work coil. Also, in the same vein, have you measured the mains input current when it is driving your work coil? Again, that would give an indication of how hard the PSU is working to drive your setup. I checked the 1000W Panasonic microwave that I have. On full power and with 241 volts on the mains, it was drawing 6.3A as measured by my clamp meter. That is somewhat over the nameplate rating of 5.3A. The difference may be because the current drawn is not sinusoidal, and as a consequence, my meter may not be reading the true RMS value that is quoted on the name plate.. As when I measured the PSU frequency, it took a few seconds for the input current to ramp up to that steady figure. Returning to the PSU frequency question. You have not indicated the number of turns that are on the primary of your external transformer. Even if the number of turns replicates what was on the on-board transformer, and even if the ferrite cores are identical, the fact that your external transformer core has a larger air-gap between the core halves,( you indicated in your reply that it is 5mm) that would mean that its primary would have a lower inductance than that of the original transformer. That would cause the magnetising current to ramp up faster. That difference alone would tend to push up the frequency, if, and it is an “if”, the PSU control circuitry is configured to switch off the magnetising current when it reaches a particular maximum current. How long the flyback part of the cycle takes is more dependent on the number of secondary turns and the load on the secondary side. If the drive circuitry is configured to cut off at a certain magnetising current, that would help to explain why you have been able to get this far without letting the blue smoke out of the PSU. Are you still working with the original PSU that you started with, or have you let the smoke out of some other PSUs in getting to this far? If you are still working with the original one, it is a tribute both your efforts and whatever protection measures the designers incorporated in the PSU circuitry. Does the core in your external transformer get hot? Probably not given the large 5mm air gap, which would keep it from magnetically saturating. It would be really interesting to see the oscilloscope waveform of the voltage on the work-coil. What voltage does your meter measure across the work-coil? Cheers
I have not checked the frequency while under load. I will have to check that next time. I do remember years ago checking it and it was lower under load but I can’t remember all the details. There is one thing I noticed that on my video the water did not start to bubble until 3 seconds after I pushed the start button and it was even longer when the can started to change colour without water. Videos are great for picking up those small details. Yes I have checked the mains current draw on an older version of my induction heater and when it starts on p10 there is a boost function to push more power so the food heats up quicker. It lasts for 3-5 minutes. Most people use microwave ovens only for short periods of time to reheat foods so that is why it is there. Another feature for you to look at is on the p10 level you can only dial up 30 minutes max but dial up p9 you can dial up 99minutes. At the highest power level the inverter cannot be used all the time and I suspect that is why some microwaves have dead inverters because people dial up 30 minutes and then keep dialing up more time until the inverter stops working. About the amount of turns on the primary side, I put a few more turns than was on the original transformer. The inverter transformer always has a large gap on them and so does the CRT flyback transformers from TVs. This is why I put a large gap on my transformer. I think it is to weaken the magnetic field because there is DC and AC going through the primary side. This why ignition coils on cars get so hot. The ferrite core on my transformer did get hot but a cooling fan kept it at reasonable temp. When you say “ blue smoke comes out of the PSU” is that a figure of speech? The inverter always fails short circuit, no smoke here. The fuses in the microwave never blow even though they are fast acting. The circuit breaker in my shed always trips before a fuse blows. To answer your question, is this the original PSU? My original experimental induction heater still works after 14 years. I thought it would be a once in a lifetime find to get an inverter microwave but as they became more common place they were easy to get. Since I have made that video I have destroyed two inverter PSUs trying out modifications but it is no big deal because they are so easy to come by. The early inverters had very little in the way of protection circuits but it let me see how far I could go but the later inverters have very sophisticated protection circuits so it is very difficult to destroy an inverter. For years I did not want change my original set up but I realized that without experimentation it would not progress further. As I am a motor mechanic, trying to figure out electronics and learning how to do things has been a steep learning curve. Also induction heating can be a black art with very little information around to learn from. I do not have an oscilloscope and do not know how to use one. I did measure the voltage across the work coil and it was about 32 volts. I know my meter will not give an accurate reading of voltage above 300 Hz but I have another method to find out the true voltage.
@@luckygen1001 Thank you for that detailed reply. The microwave PSUs are really just a powerful switchmode power supplies. As a class of circuit, switchmode PSUs tend to be unforgiving of fault conditions or modification. However, some of the ancillary devices, like the IGBT gate driver ICs that are used in them now tend to have protection facilities like overcurrent detectors, which can switch the power transistors off on a cycle-by-cycle basis. In a fault condition, the aim is to do that before the main switching transistors destroy themselves and their associated components. That fits with your experience that the PSUs have become more robust to your experiments. The available power transistors have also become beefier as well. Induction heating driver circuits are more usually symmetrical push-pull or “H” bridge topologies that drive both halves of the cycle equally. That is why, looking at my spare microwave PSU, I was inclined to think that nothing useful could be done with it in that direction because was evident that it is a flyback inverter. You have shown that something can be done with them. Thomas Edison famously maintained that he didn’t want university graduates working for him because all they could do was tell him all the reasons why whatever he wanted to do couldn’t be made to work. Whereas, other people that Edison employed would just keep trying. I was wrong when I thought no useful induction heating could be achieved with these PSUs. The opposite to Edison’s approach is typified by what Stanley Hooker achieved. As a relatively recent Oxford graduate with a PhD in fluid dynamics, Hooker got a job with Rolls Royce. He had never seen an aircraft engine supercharger before. But armed with some fluid dynamics theory, in short order, Hooker was able to improve their superchargers and thereby increase the aircraft service ceilings by thousands of feet - That became no small benefit in the midst of WW2. I expect that you are aware of the various induction heater boards that are now offered from China at modest price. An earlier commenter, Godfrey Poon , seems enthusiastic about the board with a 2500W rating that he obtained. From the photos and description, it looks like they are push-pull, “resonant Royer”, type oscillators. That is an elegantly simple circuit that automatically drives the work-coil and its parallel capacitor combination at its resonant frequency, irrespective of changes in the load etc. The circuit also has the advantage that the switching transistors switch at a point in each cycle where the transistors are less challenged in terms of the current and voltage that they are switching. That reduces the stress on the transistors and the rest of the circuit, whereas in the microwave PSU, the main power transistor has to switch off at maximum current. That’s why the microwave PSUs have such a brute of a switching transistor, with 60A and 1000V ratings. And that is why they have quite a large auxiliary transistor, just to catch the inductive kick back on the primary winding after the main transistor switches off. However, even if the microwave PSUs are not ideal as a source of high frequency power for small scale induction heating, given the huge number of these PSUs in the scrap microwave stream, it will be really interesting to see what is achievable with them. Here is a link to a little more information on the microwave PSU. Again, it warns of the special hazards of these devices, so stay safe everyone. www.avdweb.nl/tech-tips/tips-2/panasonic-hv-psu Here is a link to a US Panasonic training document. The two PSU circuit diagrams are not the same as the one shown in either the link above or in the earlier link that I posted. The circuits in the link below are for 120V supply, whereas the other one is for 220-240V supply. That may be the reason for the difference, or it might be because these are older circuits. The US document is undated. However, it does confirm what I suspected earlier, which is that the inverter frequency changes appreciably with variation in load. media.datatail.com/docs/manual/371449_en.pdf On the theme of scrap microwave ovens, the power transformer, or perhaps a pair of such transformers, from older style microwaves, if rewound with suitable low voltage secondary could form the basis of the 48V 50A power supply needed to fully power one of the Chinese induction heater boards. Judging by fan cooling provided, some parts of these boards must be working pretty hard. Searching for (2500W ZVS Induction Heater Induction Heating PCB Board) will turn up many sellers offering these, both with and without a power supply and various accompanying items. Cheers
It is very interesting that you mentioned Edison. When I first found an inverter microwave I showed it to an electrical engineer, he said that the topology of the inverter was wrong so it could not work as an induction heater. He was very surprised when I showed it to him heating a can to red heat. Two sayings come to mind about what the EE said, 1. Two heads are better than one 2. A fresh pair of eyes helps solve a problem. Ha! great minds think alike, one of those websites showed him doing the same thing as me, wrapping some wire around HF transformer to make measurements. The second website says that all power levels are on all the time, this is not true. Put your clamp meter on the 240 volt lead and select power levels P3,P2,P1 and you will see that it switches on and off like a normal microwave oven. Regarding the sharp inverter oven I did some tests to see what the frequency was with the magnetron disconnected, it was 33 kHz. It was 36 kHz with the magnetron connected.I was reading some interesting info about how to use an induction furnace, it said a half bridge inverter output can go directly to the work coil without a transformer in between but a full bridge inverter needs a transformer in between the inverter and the work coil, why is that? It was in an inductotherm training manual. This is why I put a transformer in between the inverter and the work coil.
One minute twenty seconds and water goes from room temperature to boiling is just super quick. What is the BTUs of that happening ??? Also, would using this type of setup be able to heat room air super quickly and supper efficiently ??? I know this is not what you were doing the video about but your thoughts would be appreciated Sir. Also, is there any way the induction heating could be spread all over the item instead of starting to heat in the middle ??? Thanks, VF
@@luckygen1001 Would you be able to do a video on making a heater using induction current ??? I am sure you could figure out something unique for this idea luckygen1001. Thanks and good luck. VF
RE: Glass sleeve for induction furnace Greetings from Canada ! I’ve been a fan of tour You tube channel for years now, and I’ve always liked your experimental and innovative approach. I particularly like your crucible cart / trolley ! Like you, I have done quite a lot of metal casting, bronze sculpture mainly and enjoy building my own equipment. I’m a glass blower (flame work mostly), so hot glass has been my livelihood for over 45 years. Why the glass didn’t shatter: My short answer is that you were lucky enough not to deliver enough thermal shock to the glass sleeve to cause fracturing. The long version: Like all materials, glass expands with heat & contracts on cooling. It takes time for the heat delivered to a tube surface to penetrate deeper into the glass & opposing surface. At the beginning of the heating process one surface is expanding (rapidly), while the deeper body and other surface are in more rigid states. I believe this is called differential thermal expansion, and this causes enormous stress in the glass, which can lead to the shattering you were expecting. Delivering heat to a localized area has the same effect, with a zone in expansion (hot), and the surrounding cooler areas holding firm. If the heating process is even over the entire glass surface, and the heating rate is slow enough for the glass wall to expand evenly, then the tube has a reasonable chance of survival. Your jar is likely a “soda-lime" type, formulated to have an expansion coefficient (COE) of 9x10 -7. This is quite high and it's vulnerable to thermal shock, whereas lab vessels or coffee pots made from a borosilicate type glass (pyrex, simax etc) are formulated to have a COE of 3.3 x 10-7. This means that they expand 1/3 less with heat than bottle glass, and is part of the reason for their resistance to thermal shock. Counter-intuitively, thin walled vessels stand up better than thick ones to thermal shock, since the heat penetrates more quickly and the expansion then occurs more evenly. This is only half the story. As the heat is removed, cooling begins and the reverse process occurs. The outer glass surface can disperse its heat to the air faster than the deeper body. The outer surface is in rapid contraction, and the inner core either still expanding or holding firm. If the temperature reaches the stress zone then this can lead to permanent internal stresses in the glass, which can cause fracture at any time…seconds or years, and the stresses are invisible. You can detect internal stress with a polariscope, which you can cobble together with 2 polaroid filters and a light source. Glass blowers anneal all glass after fabrication to minimize internal stress. The glass is heated to its”annealing range” (below softening), held at that temp long enough for stress to be relieved, and cooled slowly and evenly to avoid further introduction of stress. Your glass sleeve may contain internal stress, and if so could fracture, just sitting on a shelf. Len Chodirker Glass Sculpture Studios (Canada)
I'm not surprised. Annealing right after the test might have prevented this, but hardly worth the effort. Some kind of ceramic cylinder, might be more suitable for this task.
Did you wire these two arrangements with one or two turns around the hf transformer secondary winding? Or did you rewind the transformer secondary in some way? Thanks for the excellent video.
Great vid, I was half asleep when I started watching this excellent vid, and was expecting a microwave gun furnace. So I was confused at the point you were talking about the inverter. Thanks for trying this out and getting some great results others can work with.
As a home hobbyist of e-waste precious metals recovery I acquire many kilos of copper, aluminum, and some alloy gold and silver. One day I would like to melt the copper into bars for hoarding. My concern is will a high frequency induction heater work on standard house hold current of 220v with a standard 15-20 amp circuit breaker in the electrical panel?
The induction heater I made in the video will not melt copper without a lot of modifications but have a look at "frenchcreekvalley" channel on youtube. He uses an induction melter he got from ebay and it works from a 220 volt 15-20 amp outlet. Power is everything when it comes to melting metals.
Reguarding the stranded wire coils, Adding layer of insulating kaowool to the tin can would thermally insulate the coil from the tin can. Painting the outside layer of the kaowool with water glass (sodium silicate) and cure it with co2 forms a hard shell on which you can wrap your coil over vertical tooth picks so as maximize the surface area of the wire in contact with air carrying away excess heat. Still. This might help somewhat. Butwatter cooled copper tubing makes a great coil.
Why didn't the glass shatter? My thought is that, this being an induction furnace, the tin can was carrying all the induced current, which caused it to heat up. The glass is not a conductor, so would not be affected by the induction, but by convection or radiation. The glass is not a good thermal conductor,, and would depend on radiant heat along with some convection heat to get any heat into it. Since the glass remained in the middle of the furnace after removing the crucible it could still receive some radiant heat, but would cool down slowly in the ambient air, so it did not receive any thermal shock (such as pouring cold water on it when it was hot). Also, there was no apparent pre-existing stresses in the glass that were released during the heating.
The melting point for pewter is reported as 170 to 230 degrees C. The point where steel is glowing red is somewhere in the range of 600 degrees C. Explains the speed. Of course, the mass also matters - no need to remind me. As to the glass - soda lime glass might be on the borderline. Borosilicate (Pyrex) should be able to handle the temperatures you achieved.
I am wondering if you would coat the induction heater coil using any type of ashes over the copper coil would increase the efficiency and reduce the heating time ??? Am really impressed that a microwave would make such a heater. Also. does using the microwave in this fashion reduce the life of the unit ??? Thanks for doing such a interesting and re-purposing of a unit that would end up in the junk pile. Look forward to more videos from you soon.
Luckygen1001. I’m a subscriber and haven’t seen a video from you for awhile. So I was super glad to see this one. Thank you for the ideas, and please stay awesome,
The thing that is easy to forget is induction heats the metal itself rather than the crusible which conducts the heat through it then into the metal. You could use a non-conductive ceramic crusible too, as the magnetic field would easily penetrate.
@@luckygen1001 iron crucible is good in that it takes full advantage of induction heating because it is the most magnetic, but a possible problem using iron crucibles with higher temp metals may be that iron gets absorbed into those metals after they starts melting, causing brittleness, etc?? Also iron looses its magnetism at some point, maybe 1300 Fahrenheit, and then is less efficient. Possibly a thin wash coat applied to inside that would also allow the heat to pass through could prevent metal from alloying with the charge? Surrounding with kaowool would help quicken melting of both pewter and zinc, and maybe even allow small quantities of aluminum.
Yes they are all good ideas. The steel crucible was only for low temperature metals and as you said once the curie point has been reached it is the same as heating non magnetic metals.
a question for you to all people watchin this video ,if we connect 2 separate 1000 watt microwave oven circuits to a single heating coil ,do you get 2000 watt power or demage to circuits
Just ask someone who has tried to connect two generators together without considering what will happen. If you want to destroy both inverters from the microwaves that is the quickest way to do it.
Because then you would see this is really only a resistive heating system. A person can make all kinds of claims if they don't present the data to back it up.
@@borisjohnson1944 Without me actually conducting this experiment myself and testing all parameters, I can't be 100% sure of what he's actually doing. The entire video is suspicious. I've built many induction heaters and this is definitely not a practical way to go about it. For part of his demonstration, he could have fill the jar with water and see if it would heat up. If it's truly inductive, the water would remain cold. Notice the break in the video at 6:48. It's like he cut out some time. Inductive heating would have turned that can red hot is mere seconds. Why did it take so long? Why is there a break in the video? Don't just assume that everything you see on TH-cam is the truth. Question everything.
@@paparoysworkshop The induction heating of the water was done via the tin can getting hot, just like it is done on a stove top. Are you sure you have built induction heaters?
Nice video! As long as uniform stress from uniform heating is maintained, the glass should hold until it melts with out cracking. In other words the temperature of the glass can't deviate from one area to another. In glass a difference in temperature causes irregular expanding, beyond the malleable limits of glass.
What an awesome project ! Bravo ! I have all the components for this project, but not a clue how to tide them together. Can you do an instructional video how to put it together or at least some photos or a scheme please. Thanks.
Could somebody please name the melting point og the 2nd batch he ´s molten? He said, it´s double as high as of the first batch (pewter at 170-230°C), but what was it really...???
Any microwave high voltage transformer will work. And since most of the world's power line transmissions are a.c. (alternating current), why an inverter circuit? Does your area use d.c. (direct current)?
yes & no? true that most of the world's power-lines [driving appliance transformers] are only 50-60Hz which luckygen1001 notes aren't effective for inductive furnace. * older microwaves implemented different heating power settings by cycling between 100% and 0% over a period of time -- e.g. using a fixed 20s cycle-time: power level 7 (70%) energizes magnetron at FULL power (@50-60Hz) for duration 14s ON followed by duration 6s OFF ... followed by 14s ON... 6s OFF... etc... Therefore, a user panel set to 14s @ 70% power on an oven with a fixed 20s cycle-time gets 14s at FULL power! Note: one of the 1st commercial microwaves Amana Radar Range was different - was truely variable power controlled by analog dial * what i gathered from the video is that many newer ovens implement variable heating power settings differently and more efficient by using an inverter that bumps the drivers to 30kHz instead of only the 50-60Hz from your mains. * Repurposed for induction furnace, the inverter's much higher frequency makes induction heating more efficient -- from what i recall -- because at higher Hz, flux penetration is closer to surface skin of conductor which saturates depths more with heat generating eddie currents -- which, in this case, is good
Luckygen, in your ultimate setup as shown in the video, have you simply disconnected the transformer on the inverter board and extended the primary driver circuit connections out to the external transformer that you have wound on a CRT EHT core? Previously, I was assuming that you still had some turns around the on-board transformer and these turns are connected to the primary of your external transformer. Some other commenters seem to have made that same assumption. However, because of the plastic shroud on the inverter, we cannot see whether you still have turns around the transformer on the inverter board or whether you disconnected the primary connections to the on-board transformer and brought them out to directly drive the primary of your external transformer. The more I look at it the more I think it might be the latter. A third alternative would be that you have left the transformer on the board still connected to the primary drive circuitry and connected the primary of your external transformer in parallel with the primary on the board transformer. Is it one of these arrangements or yet another one that I haven’t thought of? Is your external transformer core gapped where the core halves meet the same as the core of the transformer on the inverter board? The on-board transformer core has a gap of about 1mm in the external leg. Its centre leg may or may not be gapped as well. The gap is there to stop the magnetic flux in the core from reaching saturation. Here is a link with some information about this type of PSU. It provides a partial circuit diagram, which as I thought, shows it have a flyback topology, evidently with an active clamp (snubber). The link also provides info about the pulse-width-modulated control signal to the board and duly warns of the hazards of these devices. www.vk3hz.net/amps/Microwave_Oven_Inverter_HV_Power_Supply.pdf Cheers
I had a look at that link and what do I find there? a circuit diagram. I lost the one I got from a microwave oven repair shop so now I have another. I removed the transformer and used the wire to connect my crt flyback transformer. I put in a large gap 3mm in both legs so the inverter does not overload. Some models do away with the clamp altogether and use a igbt with a really high voltage rating. I think it is about 1500v.
Could you answer something for me Sir ?? Since you boiled water in 1:20 minutes. How long would it take to heat the same amount of water inside the microwave time wise ???? Just love this video Sir.
In another life many years ago I used to work in a car engine factory operating a induction heater to fit piston pins. I never had to have a lighter or matches for a smoke. A quick twiddle of the power knob and a scrap conrod would do the trick in a couple of seconds. Mind you there was a wee bit of arcing doing on down in the throat of the machine. Cheers Eric
I can't wait for the MK2 version where you cast aluminium. Could you please give some details of the transformer you used. Keep up the good work. Cheers
The transformer from the microwave oven does not have enough room to have a new primary winding and a copper tube secondary so I used a flyback transformer from an old crt tv. They have plenty of room to experiment with.
Well... Melting point of aluminum is somewhere near 660C, it is around the same temperature, where steels starts glowing red. So theoreticaly this should be possible, but it might be slow, since crucible itself takes time to get to that temperature... Maybe improving insulation might help...
A few words about the glass: What causes glass to crack or shatter is not absolute temperature, but thermal stress - that is, a high rate of temperature change, whether from cold to hot or the other way round. Another cause of thermal stress is one part of the glass seeing a much higher rate of heating than another part, especially if the boundary between the different temperature zones is narrow. The coil around the outside of the glass avoids this because it doesn't heat the glass directly - as you know, the induction heating only heats any electrically conductive materials inside the coil, whether those be metals or semiconductors like graphite or doped silicon. When you put the metal can inside the jar, the glass still does not receive much thermal stress: The highest heating occurs in the centre of the coil, with a gradual reduction of heating towards either end. Also, the slight gap between the glass and the can (because they are not a tight fit) ensures that most of the glass is not in direct contact with the can, so is not directly heated by it either. There is one particularly useful application for this kind of induction heating in chemistry: Making highly air-sensitive graphite intercalation compounds, particularly with alkali metals, such as potassium graphite (average formula KC8). To make this requires extremely pure and dry graphite and potassium metal - the latter being notoriously reactive with both air and water. Both have to be heated to high temperature inside a sealed glass tube under a completely inert atmosphere, such as high purity argon. Induction heating is ideal, since graphite can be heated this way (even as a powder) and potassium obviously can as well since it's a metal. Even as the reaction proceeds, the heating would still be effective, since the KC8 product is also electrically conductive, with a conductivity somewhere between that of the two starting materials. You can tell when it's working just by looking, since KC8 is a beautiful golden bronze colour. It is also notable for being one of the most powerful reducing agents in the universe.
Brilliant proof of concept video. I'm a foundry engineer apprentice (mech) in the UK, dealing with 6 tonne 4MW induction furnaces for cast iron production. Planning to make my own as I have the furnace knowledge, but I lack the electronics knowledge on making an inverter to power it. I see the microwave you used was 1.2kW, I'm just thinking whether it could work if a pair of equal power microwaves (same model for frequency) could be used in parallel to each other, connected at the coil to double or triple the output power and electromagnetic field to enable iron melting temperatures? I had planned to use an arc welder as it can output 250v but I haven't measured the output frequency. I've watched lots of your videos and enjoy them very much, as a fellow foundryman I have great respect for you and it would seem that what you don't know simply isn't worth knowing. Best regards from the UK
Thank you for watching my videos. This is why I used the microwave power supply, I am not smart enough to build my own inverter. If you connect two or more inverter microwaves to together it will be like connecting two electric motor drive shafts together and they will spin in two different directions. In a very short time they will over heat and destroy themselves. The same thing happens when the power transistors in the inverters do not fire at exactly the same time, they destroy themselves in a tiny fraction of a second! So you are stuck with the rated output and if you try to run the inverter at max power for a long time it will not let you dial ups hours at a time. Inverter arc welders could be used as induction heater but I have never tried that because scrap welders are hard to find. Scrap inverter microwaves are so easy to find because on garbage day there is usually at least one to pick up. I you need any help just contact me via youtube..
@@luckygen1001 Awesome videos. Flyback resonant circuits actually can be connected in parallel as their internal feedback signal to the driver chip is derived from the resonant peaks not an onboard fixed freq oscillator, so they will tend to sync up provided their individual tank circuits resonate fairly closely. To parallel them, connect the secondary (high current) outputs together (properly phased of course) , and start the inverters simultaneously. The only issue I can see is you need to make a driver circuit to drive the yellow wire at ~ 220 hz 5v with a starting duty cycle of ~ 30% low power and switch to 80% high power. I scoped the orange wire. The orange wire sends an alternating status square wave signal back to the keypad to tell the computer if the magnetron is loading up properly or open circuit, which will cause problems if you try to use 2 or more inverters in parallel with the same keypad. It's not clear on your video, did you use a single turn pickup on the inverter xfmr ?
@@luckygen1001 The ferrite transformer supplying the work coil, did you just relocate the inverter transformer off the PCB, or is it a matching transformer that you added ? Can't tell from the video with the inverter cover shield on if you just relocated the transformer to the work coil.
@@sparkyy0007 The original ferrite transformer from the inverter was not big enough to have copper tubing as a secondary winding so I used a ferrite transformer from a crt tv.
I've wondered if this were possible myself after overhearing a guy talk about making one. Never got the chance to chat him up, so knowing what wattage the microwave is would help the rest of us to know what to look out for while scrapping.
@luckygen1001 My uneducated guess is that the reason why Your glass jar didn't shatter is that You managed to heat it "evenly enough". I believe that what makes glass "shatter" are the tension that is built up between areas with "substantially different temperatures", that therefore are expanding to different degrees. The fact that You had such a comparatively large portion of the jar covered is what I believe "made it work", and I believe that if You for instance had had a taller jar and just had the same size wrapping on the mid section it might well have shattered... Well anyway thanks for the great content, always interesting. Best regards.
Your analysis is spot on. Slow, fairly uniform heating followed by similar cooling will anneal the glass. Even soda-lime, which reacts poorly to thermal shock. Borosilicate is way better, but NOT perfect; I've blown some up just cooking dinner... :-)
Many have multi function for the switch, like on my Fluke. You go to AC V, turn it to the highest setting if you don't know the range, and hit the freq button.
@@karmicmessenger I used the ferrite core from a flyback transformer from a t.v. and used 30 turns for the primary windings and 5 turns for the secondary windings.
Luckygen, I have had another look at microwave inverter board that I have. It appears the there is no feedback connection from the secondary side to the primary driver circuitry. As you mention, there is a current transformer in the primary circuitry to monitor the primary drive current . The absence of any feedback connection from the secondary suggests that the board may well continue to operate if the inverter secondary winding was removed altogether. In that case, it may be possible to remove the transformer from the board so as to get rid of the high voltage secondary altogether, and then re-wind the heavy multistrand primary and thereby make room for some turns of the copper pipe as the secondary winding. Indeed, I can see no particular reason why the inverter board would not operate with its power transformer physically removed from the board and just electrically connected by the primary. Either way, winding the copper tube as the secondary would enable you to dispense with the intermediate (ex tv?) flyback transformer core that you have interposed between the inverter and the work coil. Obviously, the copper tube secondary would have to be adequately insulated from the inverter primary, which is live at our 230 volt mains potential ( no namby pamby 110volts in this neck of the woods). When winding the transformers in pushpull or H-bridge driven inverters, you have to worry about leakage inductance between the primary and secondary windings. That is why the primary and secondary windings in computer power supplies are often split and interleaved to achieve close magnetic coupling. However, in flyback type inverters, such as I believe the microwave inverters are, leakage inductance is not an issue, so you can use plenty of insulation to physically separate and insulate the secondary copper tube winding from the primary. As you would know, It may be possible to improve the performance of your set up by adding capacitance to the work-coil circuit, either in series or parallel with the work coil, to get it closer to resonance at the drive frequency, but that may also risk letting the blue smoke out of the inverter board. The load presented by the work-coil changes dramatically as it is tuned towards resonance. The capacitors have to be able to handle the high current and when connecting smaller capacitors in parallel care has to be taken with the physical and electrical arrangement so that they share the load equally. In other words parasitic inductance in the connection arrangement can cause problems at such frequencies. If you get the idea that I am enthusiastic about your experiment, you would be right. More power to your right arm! Just make sure it is not 5,000 volt power from that inverter secondary! I would really like to meet you some day. I suspect that, like me, you are always looking at things and wondering, what else could we do with that? In my case it might have something to do with not having a particularly materially well-off childhood, although I cannot claim that we actually lived in a hole in the road. By the way, did you find a source of nickel for alloying in your cast iron? I think the best convenient source of a small quantity might be the high nickel welding rods from Bunnings. You can get 25 Bossweld 2.6mm Nickel Arc 98 stick electrodes for A$32.88. Assuming that they are only 300mm long and 98% nickel, that yields about 346 grams of nickel. That works out to be about A$94,700 per tonne or about 4.5 times the bulk nickel price, which is not that expensive for a small quantity. Cheers.
Yes, used microwave ovens have so many uses. Make sure that you look at my video “ Repurposing a microwave oven controller.” It shows in detail how it was done. Regarding the microwave oven transformer it should work disconnected from the inverter PCB. I know that manufacturers do change settings and parts so what works on one oven may not work on another. You just have to keep trying. I have avoided use caps on the work coil for two reasons, 1. The output frequency can change a lot when the inverter is under load and not under load. So a large array of caps are needed suit the changing frequency. 2. Caps in commercial induction furnaces are water cooled so how does one build a water cooled cap? Have a look at my video showing the inside of a 300Kw power supply for an induction furnace. Water cooling is used a lot. I think that we do see things in a similar way. For a long time I never had any interest in electronics but in the last 20 years that has changed because there is so much being thrown out and gives me a chance to see if I can reuse or repurpose it. I will have to look at those welding rods at Bunnings. I was thinking of using metal plating nickel but with shipping costs it may end up just as expensive as the nickel welding rods. A long time ago a friend came to visit me and saw the microwave oven transformers in my shed. He said to take of the top bridging piece and connect 12 volts to it. I was amazed at how strong the electromagnet was. One of these days I will have to make video about all the uses for a microwave oven but if I do some one will watch it and say I can think of 50 more things you have missed.
Quite interesting, I think you could increase effectiveness by taking advantage of tank circuits. if you can tune the resonance frequency of an Inductor, and capacitor to match that of the power circuit you could manage large power peaks.
Using capacitors to get a higher power factor might be a problem because as the load changes so does the power factor. I would need to have many capacitors of different values to switch over as the load changes. Having the power factor at unity would put more power into the crucible and faster melting times would result.
Facinating and slightly scary topic. Ideally I would prefer to remove the high voltage winding altogether - I presume you have just left it in place and open circuit. You have clearly disconnected the HV output from the magnetron so no fear of microwave radiation, just the 5000 volts. I didn't hear mention of your coupling winding - did you add that yourself, wonder where the wire came from. Most inductive heating products sold on ebay have direct coupling between the driver electronics (fets) and the heating coil whereas you are using several stages of transformer coupling. Again, the direct coupling approach uses parallel capacitors to resonate the heater coil with the driver frequency, I note you did not need to do that - would it run better if you did. Pretty good as it is of course.
Nice proof of concept. Fairly simple. That said I have not seen anyone else do that. Unfortunately I only have one scrap microwave and its the traditional type but if I ever come across an inverter type I will definitely give this a try.
@@luckygen1001 it is indeed rare to put out an original idea. I live in the Caribbean. No luck here with recycling centers. Heck I am struggling getting LiPo here. One supplier I found is charging almost $100 for a battery that retails on the net for less than $15. If I import I have to pay a hazardous charge of $85 on top of all other cost including shipping and then tax on that. Probably closer to $175. I refuse to pay that much for battery. I did a series of videos on solar cells and charging a car battery without a MPPT controller. I went as far on the last video as working out all the efficiencies. That I have not seen anyone else do either.
i wonder if you would end up saving any power if you used this concept to heat up the water in a hot water heating system to heat up a typical small suburban home?
Sorry to disappoint you any any way, but there's not a chance. Induction heating (properly tuned and designed) is at best 80% efficient. A standard resistive heating element is always 100% efficient. You'd end up spending MUCH more on your electricity bill that way. Only exception is when using a induction cooktop for short periods of time, because the pan itself is heated and the cooktop and coil don't need any time to heat up. Long term resistive is still better.
@@theLuigiFan0007Productions I've heard the opposite -please site your source. Even if true, induction heating definitely does have its place in industry where it is excels.
@@mevk1 www.centurylife.org/is-induction-more-efficient-than-electric-coil-or-gas-an-energy-efficiency-comparison-between-stoves/ However, it efficiency does depend heavily on the application. In the case of smelting metal it's more efficient because the metal is heating itself. In most other applications resistive will always win in efficiency, but not speed.
@@theLuigiFan0007Productions That link does not say resistance elements are 100% effecient as you claim. Far from it. It states that professional studies done by the government show induction heating is slightly more efficient. Writer of article did his own study and made his own conclusions. He claims that induction heating is more efficient if cooking time is not too long, but less efficient if cooking takes a long time. Obviously, their is not much efficiency difference between the two methods as you falsely claimed. Interestingly, the latest consumer appliance rage is a combo unit that has two induction burners and two resistance burners so you get both in one unit.
@@mevk1 Sorry for the confusion, I get what you mean now. I was talking about the act of creating heat from energy, not the overall efficiency of any one device. Once you take into account losses transferring heat, say, into a pan, you are right, resistive heating isn't 100% efficient. The act of converting power to heat was 100% efficient, something induction heating can't do. However, induction heating bypasses the need for heat transfer, thus partially negating the fact not all the input power becomes heat. For resistive heating, 1W in creates 1W of heat. For inductive it's closer to 1W in, 0.8W heat out. It depends heavily on application which has better overall efficiency. If heat transfer losses when using resistive heating exceed 20% and you're heating metal, inductive wins almost every time in overall efficiency. I guess the point I'm trying to make is explained by this example. A electric water heater has the elements submerged in the thermal load, so it achieves a very high overall efficiency, usually 90% or better. Inductively heating metal to heat the water would result in a decent drop in efficiency because not all the magnetic field is converted to heat. On the other hand, smelting steel with electric heating would result in great radiative heat losses at those temperatures unless the crucible was near perfectly insulated and very heat conductive. Applying heat from within the metal itself is a whole world better. TL;DR: Sorry for confusion. Heat source efficiency ≠ Overall application efficiency
@@niktesla3939 that is genious, but I think if you follow that turn of wire, I think it then is soldered to a flyback transformer taken form a discarded TV.
Wow, awesome. Definitely need to be on the look out for these sort of microwaves! I was expecting the glass to melt. Weird that nothing much happened to it.
So, how did you seal the exhaust pipe? Where did you get the fitting for your water system, too? You can never get a response from E waste Ben. Have a heap of electronic boards to get rid of. I live in Bendigo.
I used an arc welder to seal the bottom of the exhaust pipe. You can buy the fittings from reece plumbing supplies. Wow you are going to drive from Bendigo to ewaste bens place, the petrol costs are going to eat into your profits big time.
@@luckygen1001 And I thank you for that! The limiting factor here is the power rating of the supply in the microwave. Most large consumer versions are a kilowatt to 1.5 kilowatts. Not enough umph for many metals. But your demonstration of the lower temperature melting metals was very interesting.
I could be wrong, but it seems to me that the fans you have in use are from a computer and I think they are 5.5-volt fans, you mentioned having a 12-volt power supply, so what I think is happening is the fans are being overpowered and that would cause that sound.
Good job!👍. Have you looked at any of Dr. John Milewskis work on TH-cam using microwaves and magnetite being a susceptor that absorbs the RF and gets hotter and hotter and melts glass?
There was a website long before youtube that mentioned the same things and I tried it and it worked. You can melt metals in a microwave oven by using a crucible that has been coated with a material that will absorb microwaves.
@@luckygen1001 The developed pace of entertainment & content of luckygen's videos is truly artful. • i am concerned, however, that recyclers will begin leaving behind a glut of *non-inverter* microwave ovens to clutter our alley's & byways • luckygen, please look into developing useful projects for these ' *other* ' left behind microwave ovens? - indeed, as summer fruit season approaches, i would really like to put my own oven to better use; Do you think there might be a way to contain the plasma for use as a grape-plasma powered furnace? (even if it were fictitious, my finger will *always* hover - ready to click - over anything that involves grapes & plasma)
I would recommend that you consider to make a "High Frequency Capacitor Bank" to back up the one that is mounted on the microwave!!! In that way you can shorten the smelting time and save your self the possibility to have to run around trying to find an other microwave!
Glass breaks when the heated part expands very rapidly relative to the rest of the body. In this case the contact area between the glass and the can was little, and the thermal mass of the can was also not much, and the can was heated slowly. The over all effect was slow heat transfer form the can to the glass and therefore slow expansion. Plus glass jars are a bit heat resistant, they are not like say a flower vase. So all these little effects equal to no breakage. Im no glass expert tho, not at all :)
Don't touch the coil if it has high voltage going through it. You can use a transformer to lower the secondary voltage to a safe level. I don't think that an earth point can be connected to the coil.
@@luckygen1001 , how about when it's on without anything in the coil? looked like on other videos when they're dipping objects into the coil there's still reading amps and volts?
The copper tube coil could short itself with the contact from the exhaust tube crucible ......should the copper heater coil be insulated using fibre glass sleeve ?
Yes the copper coil could short out on steel crucible but I make sure that does not happen. I plan on using ceramic fiber cloth that is 3 mm thick to stop heat loss in the crucible.
@@luckygen1001 does cloth need to be sealed with hotface of some kind (like ceramic wool does) to prevent airborne hazardous materials? I can't wait to see you melt aluminum, copper and possibly cast iron.
Wow, will preheating via induction reduce yor fuel oil / propane consumption and reduce length of melt. It also might extend the life of the crucible. Just thinking.
Great work I'm very intrigued! I have made a Tesla coil out of 2 microwaves with the old transformer type. Could you please share any info for the mod that you did to the board? Would be much appreciated. Subscribed cause of this video. Thanks
@@luckygen1001 so are you running that inverter at 120 vac or 240 vac? No way an American power supply could boil water that quickly, unless that water started the test at around 180 degrees f. We only have max 15 amps at 120 vac. After that the breaker trips.
@@markhonea2461 The inverter is running from a 240 volt outlet and the water temperature was at room temperature (20C)before the power was switched on.
Hey lucky just having a look when your measuring the frequency output. Is your multimeter on Vac instead of Hz? Just asking in case your reading was 30mv from the inductance or 30kHz By the way it’s good to see some aussies floating around on the TH-cam’s, really enjoy watching your stuff mate.
@@luckygen1001 you have to know the inductive reactance (2[pi]fL) of the driven coil at the frequency you're using, then you get a capacitor that will have the same reactance (1/(2[pi]fC)) as the coil and that will produce a resonant circuit. Being in resonance also means the power factor is '1' - perfect
@@Gaark @luckygen1001 :: if you went back to the configuration when the coils are still connected to the microwave & magnetron, ... try a grape fueled plasma furnace ! ( just line the bottom with partially-sliced grape halves - 8
Awesome? This was as informative as an ehow video. "take some wires and hook them to the circuit board" Gee thanks, Mr. 1001. Now I will build an atomic bomb with such detailed information. Awesome? No.
@@luckygen1001 I am working on mine, though I don't know if an arch furnace would be easier to build. But don't hold your breath, I get about 10 minutes of free shop time a month.
Guaranteed the dude is not marries nor no children. Using, bricks, the dirty jar, tin can, buckets stashed, hoses around with a microwave to build a furnace that needs copper welding. If married with a kid, this project will take a year and abandon half way.
I've recovered about 30 microwave ovens roadside when doing "asset recovery sweeps" in my neighborhood, a fair number of them only needed one of the 3 safety interlock snap action switches replaced to become 100% functional again- people just don't fix anymore, they simply replace.
People are to scared to fix, as insurance will use any excuse to deny your claim. Oh you repaired the microwave well that clearly cased the heater in the other room to explode, claim denied!!
@@Dust599 ......tooooooooooooo ?! Lol !
"asset recovery sweeps", sounds so much classier than "salvaging garbage for parts", I'm gonna use this from now on
@@LateNightHacks Me too! And something more likely to get past the wife. A.R.S. "Honey, I need to get off my arse and go out on an A.R.S."
I hear ya, I have 7 large flat screen TV's in my living room at the moment, I fixed one with a couple capacitors, a different one still has the thin clear plastic protector film on the plastic case. It looks as if it never even got dusty once. They didn't have it long, and she dropped a plastic cup, and it bumped the screen. (not very hard she said) The screen turned instantly, completely black......hmmm.... its a 62" Vizio
Good Luck with BeachsideHanks Microwave Oven Sales and Service :)
A couple of pointers you may wish to try on the coil side.
1. Get a ceramic crucible, the energy will be acting on the metal you are melting and not the steel crucible making it more efficient
2. wrap the coil with a thermal blanket (you can easily find thermal shielding tape used on high temp exhausts) to protect your coil and avoid shorts
@@brianmurphy9112 ahhh... no
both ferrous and non-ferrous metals can be heated by induction. Look up "eddy currents", these are produced in the material by the rapidly changing magnetic currents around the material, it only needs to be conductive.
@@brianmurphy9112 Magnetic stainless steel works.
@@lancer2204 Excellent point, induce only the metal to melt, not wasting it in the container
Can also add some insulation around the ceramic crucible.
I think that a poor idea because at a certain temperature metal is no longer magnetic. That's why you can only see glowing metal parts in these coils. You need the crucible to have a higher temperature than the metal you wish to melt and you can't do that with ceramic(non-magnetic materials). Also, insulating the coil raises its temperature so you're negating the water cooling.
A small suggestion: it's best to fill the coils from the bottom with the drain from the top. This avoids any chance of air bubbles inside the coil, which of course won't contribute to cooling. Having the water tank raised as you have is good, as this will force water by gravity from the bottom to the top of the coils with no problem.
With your glass, of it is heated evenly it will not break. It is when you get a colder spot that the thermal expansion varies and different tensions in the glass will cause it to shatter. Having said that I did expect it to break at the base due to the different thickness of the base!
Well done and I'll be keeping an eye out for an induction microwave, you are thoroughly worth subscribing to! 👍
Also glass gets more flexible and soft when heated up, compensating for the stress.
It could have broken when cooling down though.
Well, let's not paint the devil on the wall. The experiment went well.
right on! Hot plates break regular glass all the time because of uneven heating and thermal expansion. Use Pyrex, not as vulnerable - though it is spectacular when it does blow up.
@@flashpointrecycling Yes indeed, I had a Pyrex jug go on me in the microwave for some reason (it may have had a small chip/crack) and it was explosive!
LuckyGen, you are a master fabricator and inventor. I always enjoy your videos and the stuff that you accomplish because no one ever told you that you could not do it, so you just did it. The glass did not shatter because you did not thermally SHOCK it. It heated up slowly as the crucible heated up. Glass, depending, starts to flow around 2000F, ever see a 'hot shop' for glass work, very high temps. What you REALLY want to do is take a clay style or type crucible and wrap it in fluffly white aluminasilica high temp insulation, 1/2" should work. Put that inside a little larger diameter induction coil and then place the metal inside the CLAY crucible that you want to melt. The clay won't heat up from the induction field. Right now you are heating the 'pipe' and that heats the metal and melts it. If you use clay and INSULATE IT then the energy will melt the metal in the crucible and melt it even faster. If you can prevent the HEAT of the melt LEAVING the crucible by 1: radiation 2: conduction and 3: convection then you can EASILY melt stainless steel in the crucible. There is no limit to the upper temp. The only limit is the higher the temp the higher the delta T and thus the higher the heat transfer to the outside world. If you did not loose heat you could go to a million F....but at some time the heat loss will equal the heat input in and you won't go any hotter. You can't use a graphite crucible because that will be the same as the thin wall iron tube you used. Graphite conducts electricity. I'd suggest experimenting with clay. In fact, I'd LOVE to see a video from you on making a clay crucible. "fire clay" can easily hold molten steel, its what they use in the foundry that is still in the Pittsburgh area, (Braddock PA). All steel making cupolas use fireclay.
I was thinking that either way there will be heat losses using a steel crucible or a clay crucible. A clay crucible would take a lot of heat from the metal as it heats up. This is why I made a gap between the coil and the steel crucible so I could slip a thin piece of ceramic fiber to slow down the heat loss. I tried to make crucibles years ago and they were all failures. I think it is easier to buy crucibles than to make them yourself.
He's scheming already. I can't wait, let's go! Will silicon crucible work?
I don't know as I have never used a silicon carbide crucible.
@@luckygen1001 what the temp for this?
This foundry project is pretty cool, but I like blacksmithing and there are days when we can't burn coal. I think this would be a great heater for knife making.
good demonstrations, BUT would love to know how you biult the contraption.
If you're asking because you want to do it yourself and don't know how, it would probably be a manslaughter charge for anyone who gives you instructions. You only need a very basic understanding of the relevant physical laws and experience with electronics (and electricity) to be able to work this out (and improve on it). High voltage experiments like this are not where you should start learning, because if you make a tiny mistake, you die.
When you 'checked the frequency' your meter was set to volts AC, the Hz range is at the top of the dial
FYI, His meter has a hertz button that is engaged while he is on the a/c setting to give the frequency readout.
Also FYI Mr sparky ...you just got served😂
Since there is so much heat when using a induction heater, how would one make the efficiency become much higher ??? Thanks
Use lots of insulation.
@@luckygen1001 That does make sense.
THE GLASS
There are two reasons any object might break or melt in an induction heating device.
1. The molecular movement caused by the induction device and
2. The secondary temperature generated by the object being heated.
First the induction device only resonates the atoms of metals. The glass atoms are not affected. The secondary contact heat from the coil was sufficiently evenly distributed on the structure of the glass to cause expansion of the area of glass to induce a crack.
It appears to me that what you measured with the meter is that your single-turn secondary winding was producing 30Volts AC. The meter was set to its AC voltage position, rather than the frequency (Hz) position so it was not measuring 30kHz.
Have a look at the video again and see that my meter has a blue Hz button. If I select AC or DC mode and press the blue Hz button it will measure frequency. Also have a closer look at readout, it shows 32.00k.
I thought the same thing (30 Volts AC). Went back and checked the video but the quality is to poor to be able to make out the k on the meter.
@@luckygen1001 Sorry, my mistake. The blue button isn't really legible in the video, and there is a Hz setting on the selector switch, which led to my error.
I'm pretty sure this gentleman knows how to set his meter to read frequency if he is able to successfully modify a microwave inverter, without it going bang.
@@luckygen1001 Hmmm. According to the QM1535 manual, it should be set to Hz, not Volts, to read frequency. The blue button selects between duty cycle and frequency measurement when the meter is set to Hz. Maybe you have discovered an undocumented feature of the meter.
The glass heated uniformly enough.
When one part of a glass object gets heated while the other part remains cooler it gets to a point that the hotter part expands more than the cooler part causing internal molecular stress that leads to fractures in the glass
Luckygen have you checked the frequency of the inverter when it is driving your work coil? The reason I ask is because I noticed that when I checked the PSU in my spare microwave, the frequency is below 30 kilo Htz when it first starts up. Presumably the lower frequency operation occurs before the magnetron emitter heats up and the magnetron draws power. That variation in frequency suggests that the PSU does not operate at a fixed frequency. Rather, the ramping up in frequency would be consistent with what would happen if the PSU control circuitry cuts the magnetisation current off when it reaches a particular value in the cycle. If that is the way it behaves, the frequency would go up if your setup is making the PSU work harder than it normally does when driving the magnetron, Hence, my question about what is the frequency when driving your work coil. Also, in the same vein, have you measured the mains input current when it is driving your work coil? Again, that would give an indication of how hard the PSU is working to drive your setup. I checked the 1000W Panasonic microwave that I have. On full power and with 241 volts on the mains, it was drawing 6.3A as measured by my clamp meter. That is somewhat over the nameplate rating of 5.3A. The difference may be because the current drawn is not sinusoidal, and as a consequence, my meter may not be reading the true RMS value that is quoted on the name plate.. As when I measured the PSU frequency, it took a few seconds for the input current to ramp up to that steady figure.
Returning to the PSU frequency question. You have not indicated the number of turns that are on the primary of your external transformer. Even if the number of turns replicates what was on the on-board transformer, and even if the ferrite cores are identical, the fact that your external transformer core has a larger air-gap between the core halves,( you indicated in your reply that it is 5mm) that would mean that its primary would have a lower inductance than that of the original transformer. That would cause the magnetising current to ramp up faster. That difference alone would tend to push up the frequency, if, and it is an “if”, the PSU control circuitry is configured to switch off the magnetising current when it reaches a particular maximum current. How long the flyback part of the cycle takes is more dependent on the number of secondary turns and the load on the secondary side. If the drive circuitry is configured to cut off at a certain magnetising current, that would help to explain why you have been able to get this far without letting the blue smoke out of the PSU.
Are you still working with the original PSU that you started with, or have you let the smoke out of some other PSUs in getting to this far? If you are still working with the original one, it is a tribute both your efforts and whatever protection measures the designers incorporated in the PSU circuitry. Does the core in your external transformer get hot? Probably not given the large 5mm air gap, which would keep it from magnetically saturating.
It would be really interesting to see the oscilloscope waveform of the voltage on the work-coil. What voltage does your meter measure across the work-coil? Cheers
I have not checked the frequency while under load. I
will have to check that next time. I do remember years ago checking it and it
was lower under load but I can’t remember all the details. There is one thing I
noticed that on my video the water did not start to bubble until 3 seconds
after I pushed the start button and it was even longer when the can started to
change colour without water. Videos are great for picking up those small
details. Yes I have checked the mains current draw on an older version of my
induction heater and when it starts on p10 there is a boost function to push
more power so the food heats up quicker. It lasts for 3-5 minutes. Most people
use microwave ovens only for short periods of time to reheat foods so that is
why it is there. Another feature for you to look at is on the p10 level you can
only dial up 30 minutes max but dial up p9 you can dial up 99minutes. At the
highest power level the inverter cannot be used all the time and I suspect that
is why some microwaves have dead inverters because people dial up 30 minutes
and then keep dialing up more time until the inverter stops working. About the
amount of turns on the primary side, I put a few more turns than was on the
original transformer. The inverter transformer always has a large gap on them
and so does the CRT flyback transformers from TVs. This is why I put a large
gap on my transformer. I think it is to weaken the magnetic field because there
is DC and AC going through the primary side. This why ignition coils on cars
get so hot. The ferrite core on my transformer did get hot but a cooling fan
kept it at reasonable temp. When you say “ blue smoke comes out of the PSU” is
that a figure of speech? The inverter always fails short circuit, no smoke
here. The fuses in the microwave never blow even though they are fast acting.
The circuit breaker in my shed always trips before a fuse blows. To answer your
question, is this the original PSU? My original experimental induction heater
still works after 14 years. I thought it would be a once in a lifetime find to
get an inverter microwave but as they became more common place they were easy
to get. Since I have made that video I have destroyed two inverter PSUs trying
out modifications but it is no big deal because they are so easy to come by.
The early inverters had very little in the way of protection circuits but it
let me see how far I could go but the later inverters have very sophisticated
protection circuits so it is very difficult to destroy an inverter. For years I
did not want change my original set up but I realized that without
experimentation it would not progress further. As I am a motor mechanic, trying
to figure out electronics and learning how to do things has been a steep
learning curve. Also induction heating can be a black art with very little
information around to learn from. I do not have an oscilloscope and do not know
how to use one. I did measure the voltage across the work coil and it was about
32 volts. I know my meter will not give an accurate reading of voltage above
300 Hz but I have another method to find out the true voltage.
@@luckygen1001 Thank you for that detailed reply. The microwave PSUs are really just a powerful switchmode power supplies. As a class of circuit, switchmode PSUs tend to be unforgiving of fault conditions or modification. However, some of the ancillary devices, like the IGBT gate driver ICs that are used in them now tend to have protection facilities like overcurrent detectors, which can switch the power transistors off on a cycle-by-cycle basis. In a fault condition, the aim is to do that before the main switching transistors destroy themselves and their associated components. That fits with your experience that the PSUs have become more robust to your experiments. The available power transistors have also become beefier as well.
Induction heating driver circuits are more usually symmetrical push-pull or “H” bridge topologies that drive both halves of the cycle equally. That is why, looking at my spare microwave PSU, I was inclined to think that nothing useful could be done with it in that direction because was evident that it is a flyback inverter. You have shown that something can be done with them. Thomas Edison famously maintained that he didn’t want university graduates working for him because all they could do was tell him all the reasons why whatever he wanted to do couldn’t be made to work. Whereas, other people that Edison employed would just keep trying. I was wrong when I thought no useful induction heating could be achieved with these PSUs. The opposite to Edison’s approach is typified by what Stanley Hooker achieved. As a relatively recent Oxford graduate with a PhD in fluid dynamics, Hooker got a job with Rolls Royce. He had never seen an aircraft engine supercharger before. But armed with some fluid dynamics theory, in short order, Hooker was able to improve their superchargers and thereby increase the aircraft service ceilings by thousands of feet - That became no small benefit in the midst of WW2.
I expect that you are aware of the various induction heater boards that are now offered from China at modest price. An earlier commenter,
Godfrey Poon , seems enthusiastic about the board with a 2500W rating that he obtained. From the photos and description, it looks like they are push-pull, “resonant Royer”, type oscillators. That is an elegantly simple circuit that automatically drives the work-coil and its parallel capacitor combination at its resonant frequency, irrespective of changes in the load etc. The circuit also has the advantage that the switching transistors switch at a point in each cycle where the transistors are less challenged in terms of the current and voltage that they are switching. That reduces the stress on the transistors and the rest of the circuit, whereas in the microwave PSU, the main power transistor has to switch off at maximum current. That’s why the microwave PSUs have such a brute of a switching transistor, with 60A and 1000V ratings. And that is why they have quite a large auxiliary transistor, just to catch the inductive kick back on the primary winding after the main transistor switches off.
However, even if the microwave PSUs are not ideal as a source of high frequency power for small scale induction heating, given the huge number of these PSUs in the scrap microwave stream, it will be really interesting to see what is achievable with them. Here is a link to a little more information on the microwave PSU. Again, it warns of the special hazards of these devices, so stay safe everyone. www.avdweb.nl/tech-tips/tips-2/panasonic-hv-psu
Here is a link to a US Panasonic training document. The two PSU circuit diagrams are not the same as the one shown in either the link above or in the earlier link that I posted. The circuits in the link below are for 120V supply, whereas the other one is for 220-240V supply. That may be the reason for the difference, or it might be because these are older circuits. The US document is undated. However, it does confirm what I suspected earlier, which is that the inverter frequency changes appreciably with variation in load. media.datatail.com/docs/manual/371449_en.pdf
On the theme of scrap microwave ovens, the power transformer, or perhaps a pair of such transformers, from older style microwaves, if rewound with suitable low voltage secondary could form the basis of the 48V 50A power supply needed to fully power one of the Chinese induction heater boards. Judging by fan cooling provided, some parts of these boards must be working pretty hard. Searching for (2500W ZVS Induction Heater Induction Heating PCB Board) will turn up many sellers offering these, both with and without a power supply and various accompanying items. Cheers
It is very interesting that you mentioned Edison. When I first found an inverter microwave I showed it to an electrical engineer, he said that
the topology of the inverter was wrong so it could not work as an induction heater. He was very surprised when I showed it to him heating a can to red
heat. Two sayings come to mind about what the EE said, 1. Two heads are better than one 2. A fresh pair of eyes helps solve a problem. Ha! great minds think alike, one of those websites showed him doing the same thing as me, wrapping some wire around HF transformer to make measurements. The second website says
that all power levels are on all the time, this is not true. Put your clamp meter on the 240 volt lead and select power levels P3,P2,P1 and you will see
that it switches on and off like a normal microwave oven. Regarding the sharp inverter oven I did some tests to see what the frequency was with the magnetron
disconnected, it was 33 kHz. It was 36 kHz with the magnetron connected.I was reading some interesting info about how to use an induction furnace, it said a half bridge inverter output can go directly to the work coil without a
transformer in between but a full bridge inverter needs a transformer in between the inverter and the work coil, why is that? It was in an inductotherm
training manual. This is why I put a transformer in between the inverter and the work coil.
One minute twenty seconds and water goes from room temperature to boiling is just super quick. What is the BTUs of that happening ??? Also, would using this type of setup be able to heat room air super quickly and supper efficiently ??? I know this is not what you were doing the video about but your thoughts would be appreciated Sir. Also, is there any way the induction heating could be spread all over the item instead of starting to heat in the middle ??? Thanks, VF
I am not sure if air will heat as well as water. No the magnetic field is the strongest in the middle so it always starts there.
@@luckygen1001 Would you be able to do a video on making a heater using induction current ??? I am sure you could figure out something unique for this idea luckygen1001. Thanks and good luck. VF
@@luckygen1001 Thanks
RE: Glass sleeve for induction furnace
Greetings from Canada !
I’ve been a fan of tour You tube channel for years now, and I’ve always liked your experimental
and innovative approach. I particularly like your crucible cart / trolley !
Like you, I have done quite a lot of metal casting, bronze sculpture mainly and enjoy building my own
equipment. I’m a glass blower (flame work mostly), so hot glass has been my livelihood for over 45 years.
Why the glass didn’t shatter:
My short answer is that you were lucky enough not to deliver enough thermal shock to the glass sleeve
to cause fracturing.
The long version:
Like all materials, glass expands with heat & contracts on cooling. It takes time for the heat delivered to
a tube surface to penetrate deeper into the glass & opposing surface. At the beginning of the
heating process one surface is expanding (rapidly), while the deeper body and other surface are in more
rigid states. I believe this is called differential thermal expansion, and this causes enormous stress in the
glass, which can lead to the shattering you were expecting. Delivering heat to a localized area has the same
effect, with a zone in expansion (hot), and the surrounding cooler areas holding firm.
If the heating process is even over the entire glass surface, and the heating rate is slow enough for the glass
wall to expand evenly, then the tube has a reasonable chance of survival. Your jar is likely a “soda-lime"
type, formulated to have an expansion coefficient (COE) of 9x10 -7. This is quite high and it's vulnerable to
thermal shock, whereas lab vessels or coffee pots made from a borosilicate type glass (pyrex, simax etc)
are formulated to have a COE of 3.3 x 10-7. This means that they expand 1/3 less with heat than bottle
glass, and is part of the reason for their resistance to thermal shock. Counter-intuitively, thin walled vessels
stand up better than thick ones to thermal shock, since the heat penetrates more quickly and the expansion
then occurs more evenly.
This is only half the story.
As the heat is removed, cooling begins and the reverse process occurs. The outer glass surface can disperse
its heat to the air faster than the deeper body. The outer surface is in rapid contraction, and the inner core
either still expanding or holding firm. If the temperature reaches the stress zone then this can lead to
permanent internal stresses in the glass, which can cause fracture at any time…seconds or years, and the
stresses are invisible. You can detect internal stress with a polariscope, which you can cobble together with
2 polaroid filters and a light source.
Glass blowers anneal all glass after fabrication to minimize internal stress. The glass is heated to its”annealing
range” (below softening), held at that temp long enough for stress to be relieved, and cooled slowly and evenly
to avoid further introduction of stress.
Your glass sleeve may contain internal stress, and if so could fracture, just sitting on a shelf.
Len Chodirker
Glass Sculpture Studios (Canada)
what he said. i knew that. ;-)
It did crack the next day seemly for no reason.
I'm not surprised. Annealing right after the test might have prevented this, but hardly worth the effort. Some kind of ceramic cylinder, might be more suitable for this task.
Did you wire these two arrangements with one or two turns around the hf transformer secondary winding? Or did you rewind the transformer secondary in some way? Thanks for the excellent video.
How can you be measuring frequency when your meter is set on AC voltage instead of Hz
Great vid, I was half asleep when I started watching this excellent vid, and was expecting a microwave gun furnace. So I was confused at the point you were talking about the inverter. Thanks for trying this out and getting some great results others can work with.
As a home hobbyist of e-waste precious metals recovery I acquire many kilos of copper, aluminum, and some alloy gold and silver. One day I would like to melt the copper into bars for hoarding. My concern is will a high frequency induction heater work on standard house hold current of 220v with a standard 15-20 amp circuit breaker in the electrical panel?
The induction heater I made in the video will not melt copper without a lot of modifications but have a look at "frenchcreekvalley" channel on youtube. He uses an induction melter he got from ebay and it works from a 220 volt 15-20 amp outlet. Power is everything when it comes to melting metals.
Reguarding the stranded wire coils, Adding layer of insulating kaowool to the tin can would thermally insulate the coil from the tin can. Painting the outside layer of the kaowool with water glass (sodium silicate) and cure it with co2 forms a hard shell on which you can wrap your coil over vertical tooth picks so as maximize the surface area of the wire in contact with air carrying away excess heat. Still. This might help somewhat. Butwatter cooled copper tubing makes a great coil.
Why didn't the glass shatter? My thought is that, this being an induction furnace, the tin can was carrying all the induced current, which caused it to heat up. The glass is not a conductor, so would not be affected by the induction, but by convection or radiation. The glass is not a good thermal conductor,, and would depend on radiant heat along with some convection heat to get any heat into it. Since the glass remained in the middle of the furnace after removing the crucible it could still receive some radiant heat, but would cool down slowly in the ambient air, so it did not receive any thermal shock (such as pouring cold water on it when it was hot). Also, there was no apparent pre-existing stresses in the glass that were released during the heating.
I have learned something and will study further. Thank you for sharing your experiment.
is there any concern of electrical arc between the coil and or the crusible
The voltage is to small for an arc to flash from the coil to whatever you are going to heat up.
The melting point for pewter is reported as 170 to 230 degrees C. The point where steel is glowing red is somewhere in the range of 600 degrees C. Explains the speed. Of course, the mass also matters - no need to remind me.
As to the glass - soda lime glass might be on the borderline. Borosilicate (Pyrex) should be able to handle the temperatures you achieved.
Or fused quartz would work also.
You didnt show us how you rewired the inverter. How and where do we attach the wires
Just trace the wires from the transformer to to the inverter.
You are awesome
I am wondering if you would coat the induction heater coil using any type of ashes over the copper coil would increase the efficiency and reduce the heating time ??? Am really impressed that a microwave would make such a heater. Also. does using the microwave in this fashion reduce the life of the unit ??? Thanks for doing such a interesting and re-purposing of a unit that would end up in the junk pile. Look forward to more videos from you soon.
Luckygen1001. I’m a subscriber and haven’t seen a video from you for awhile. So I was super glad to see this one. Thank you for the ideas, and please stay awesome,
The thing that is easy to forget is induction heats the metal itself rather than the crusible which conducts the heat through it then into the metal. You could use a non-conductive ceramic crusible too, as the magnetic field would easily penetrate.
That will be in a future video.
@@luckygen1001 iron crucible is good in that it takes full advantage of induction heating because it is the most magnetic, but a possible problem using iron crucibles with higher temp metals may be that iron gets absorbed into those metals after they starts melting, causing brittleness, etc?? Also iron looses its magnetism at some point, maybe 1300 Fahrenheit, and then is less efficient. Possibly a thin wash coat applied to inside that would also allow the heat to pass through could prevent metal from alloying with the charge? Surrounding with kaowool would help quicken melting of both pewter and zinc, and maybe even allow small quantities of aluminum.
Yes they are all good ideas. The steel crucible was only for low temperature metals and as you said once the curie point has been reached it is the same as heating non magnetic metals.
a question for you to all people watchin this video ,if we connect 2 separate 1000 watt microwave oven circuits to a single heating coil ,do you get 2000 watt power or demage to circuits
Just ask someone who has tried to connect two generators together without considering what will happen. If you want to destroy both inverters from the microwaves that is the quickest way to do it.
Building an induction heater to melt pewter is like building a nuclear power plant to charge my cell phone.
why zero info on the actual mods/circuits used ?
Because then you would see this is really only a resistive heating system. A person can make all kinds of claims if they don't present the data to back it up.
@@paparoysworkshop How is it resistive? The coil is cooled.
@@borisjohnson1944 Without me actually conducting this experiment myself and testing all parameters, I can't be 100% sure of what he's actually doing. The entire video is suspicious. I've built many induction heaters and this is definitely not a practical way to go about it. For part of his demonstration, he could have fill the jar with water and see if it would heat up. If it's truly inductive, the water would remain cold. Notice the break in the video at 6:48. It's like he cut out some time. Inductive heating would have turned that can red hot is mere seconds. Why did it take so long? Why is there a break in the video? Don't just assume that everything you see on TH-cam is the truth. Question everything.
@@paparoysworkshop The induction heating of the water was done via the tin can getting hot, just like it is done on a stove top. Are you sure you have built induction heaters?
@@paparoysworkshop I also run a science page so questioning everything is something I do everyday.
Is this any more efficient or easy to to build than a gas fired furnace.
No it is not as easy to build than a gas fired furnace.
Nice video! As long as uniform stress from uniform heating is maintained, the glass should hold until it melts with out cracking. In other words the temperature of the glass can't deviate from one area to another. In glass a difference in temperature causes irregular expanding, beyond the malleable limits of glass.
What an awesome project ! Bravo !
I have all the components for this project, but not a clue how to tide them together.
Can you do an instructional video how to put it together or at least some photos or a scheme please.
Thanks.
Yeah me too would be very interested to see that video. Thx
yeah im interested as well.
Could somebody please name the melting point og the 2nd batch he ´s molten? He said, it´s double as high as of the first batch (pewter at 170-230°C), but what was it really...???
Zinc.
@@luckygen1001 thanks !!!
Any microwave high voltage transformer will work. And since most of the world's power line transmissions are a.c. (alternating current), why an inverter circuit? Does your area use d.c. (direct current)?
They are used all over the world because the power can be controlled to the magnetron.
yes & no?
true that most of the world's power-lines [driving appliance transformers] are only 50-60Hz which luckygen1001 notes aren't effective for inductive furnace.
* older microwaves implemented different heating power settings by cycling between 100% and 0% over a period of time
-- e.g. using a fixed 20s cycle-time:
power level 7 (70%) energizes magnetron at FULL power (@50-60Hz) for duration 14s ON followed by duration 6s OFF
... followed by 14s ON... 6s OFF...
etc...
Therefore, a user panel set to 14s @ 70% power on an oven with a fixed 20s cycle-time gets 14s at FULL power!
Note: one of the 1st commercial microwaves Amana Radar Range was different - was truely variable power controlled by analog dial
* what i gathered from the video is that many newer ovens implement variable heating power settings differently and more efficient by using an inverter that bumps the drivers to 30kHz instead of only the 50-60Hz from your mains.
* Repurposed for induction furnace, the inverter's much higher frequency makes induction heating more efficient
-- from what i recall -- because at higher Hz, flux penetration is closer to surface skin of conductor which saturates depths more with heat generating eddie currents -- which, in this case, is good
Luckygen, in your ultimate setup as shown in the video, have you simply disconnected the transformer on the inverter board and extended the primary driver circuit connections out to the external transformer that you have wound on a CRT EHT core?
Previously, I was assuming that you still had some turns around the on-board transformer and these turns are connected to the primary of your external transformer. Some other commenters seem to have made that same assumption. However, because of the plastic shroud on the inverter, we cannot see whether you still have turns around the transformer on the inverter board or whether you disconnected the primary connections to the on-board transformer and brought them out to directly drive the primary of your external transformer. The more I look at it the more I think it might be the latter. A third alternative would be that you have left the transformer on the board still connected to the primary drive circuitry and connected the primary of your external transformer in parallel with the primary on the board transformer. Is it one of these arrangements or yet another one that I haven’t thought of?
Is your external transformer core gapped where the core halves meet the same as the core of the transformer on the inverter board? The on-board transformer core has a gap of about 1mm in the external leg. Its centre leg may or may not be gapped as well. The gap is there to stop the magnetic flux in the core from reaching saturation.
Here is a link with some information about this type of PSU. It provides a partial circuit diagram, which as I thought, shows it have a flyback topology, evidently with an active clamp (snubber). The link also provides info about the pulse-width-modulated control signal to the board and duly warns of the hazards of these devices. www.vk3hz.net/amps/Microwave_Oven_Inverter_HV_Power_Supply.pdf
Cheers
I had a look at that link and what do I find there? a circuit diagram. I lost the one I got from a microwave oven repair shop so now I have another. I removed the transformer and used the wire to connect my crt flyback transformer. I put in a large gap 3mm in both legs so the inverter does not overload. Some models do away with the clamp altogether and use a igbt with a really high voltage rating. I think it is about 1500v.
Could you answer something for me Sir ?? Since you boiled water in 1:20 minutes. How long would it take to heat the same amount of water inside the microwave time wise ????
Just love this video Sir.
In another life many years ago I used to work in a car engine factory operating a induction heater to fit piston pins.
I never had to have a lighter or matches for a smoke. A quick twiddle of the power knob and a scrap conrod would do the trick in a couple of seconds. Mind you there was a wee bit of arcing doing on down in the throat of the machine.
Cheers Eric
I can't wait for the MK2 version where you cast aluminium. Could you please give some details of the transformer you used. Keep up the good work. Cheers
The transformer from the microwave oven does not have enough room to have a new primary winding and a copper tube secondary so I used a flyback transformer from an old crt tv. They have plenty of room to experiment with.
I don’t think it will be able to melt aluminium. It’s resistance is too low.
@@mareksvrcina5279 That's what crucible for, it heats up the metal. Best to get graphite crucible that's isolated from copper coil.
Aluminum, nah that's too wimpy. He is the master of cast iron and it's the best one to cast. Let's crank up the AMPS !!!!!!!!!!!!!!
Well... Melting point of aluminum is somewhere near 660C, it is around the same temperature, where steels starts glowing red. So theoreticaly this should be possible, but it might be slow, since crucible itself takes time to get to that temperature... Maybe improving insulation might help...
A few words about the glass: What causes glass to crack or shatter is not absolute temperature, but thermal stress - that is, a high rate of temperature change, whether from cold to hot or the other way round. Another cause of thermal stress is one part of the glass seeing a much higher rate of heating than another part, especially if the boundary between the different temperature zones is narrow.
The coil around the outside of the glass avoids this because it doesn't heat the glass directly - as you know, the induction heating only heats any electrically conductive materials inside the coil, whether those be metals or semiconductors like graphite or doped silicon. When you put the metal can inside the jar, the glass still does not receive much thermal stress: The highest heating occurs in the centre of the coil, with a gradual reduction of heating towards either end. Also, the slight gap between the glass and the can (because they are not a tight fit) ensures that most of the glass is not in direct contact with the can, so is not directly heated by it either.
There is one particularly useful application for this kind of induction heating in chemistry: Making highly air-sensitive graphite intercalation compounds, particularly with alkali metals, such as potassium graphite (average formula KC8). To make this requires extremely pure and dry graphite and potassium metal - the latter being notoriously reactive with both air and water. Both have to be heated to high temperature inside a sealed glass tube under a completely inert atmosphere, such as high purity argon.
Induction heating is ideal, since graphite can be heated this way (even as a powder) and potassium obviously can as well since it's a metal. Even as the reaction proceeds, the heating would still be effective, since the KC8 product is also electrically conductive, with a conductivity somewhere between that of the two starting materials. You can tell when it's working just by looking, since KC8 is a beautiful golden bronze colour. It is also notable for being one of the most powerful reducing agents in the universe.
How powerful is it? What are the practical applications for KC8 ?
Brilliant proof of concept video. I'm a foundry engineer apprentice (mech) in the UK, dealing with 6 tonne 4MW induction furnaces for cast iron production. Planning to make my own as I have the furnace knowledge, but I lack the electronics knowledge on making an inverter to power it. I see the microwave you used was 1.2kW, I'm just thinking whether it could work if a pair of equal power microwaves (same model for frequency) could be used in parallel to each other, connected at the coil to double or triple the output power and electromagnetic field to enable iron melting temperatures? I had planned to use an arc welder as it can output 250v but I haven't measured the output frequency. I've watched lots of your videos and enjoy them very much, as a fellow foundryman I have great respect for you and it would seem that what you don't know simply isn't worth knowing. Best regards from the UK
Thank you for watching my videos. This is why I used the microwave power supply, I am not smart enough to build my own inverter. If you connect two or more inverter microwaves to together it will be like connecting two electric motor drive shafts together and they will spin in two different directions. In a very short time they will over heat and destroy themselves. The same thing happens when the power transistors in the inverters do not fire at exactly the same time, they destroy themselves in a tiny fraction of a second! So you are stuck with the rated output and if you try to run the inverter at max power for a long time it will not let you dial ups hours at a time. Inverter arc welders could be used as induction heater but I have never tried that because scrap welders are hard to find. Scrap inverter microwaves are so easy to find because on garbage day there is usually at least one to pick up. I you need any help just contact me via youtube..
@@luckygen1001
Awesome videos.
Flyback resonant circuits actually can be connected in parallel as their internal feedback signal to the driver chip is derived from the resonant peaks not an onboard fixed freq oscillator, so they will tend to sync up provided their individual tank circuits resonate fairly closely.
To parallel them, connect the secondary (high current) outputs together (properly phased of course) , and start the inverters simultaneously.
The only issue I can see is you need to make a driver circuit to drive the yellow wire at ~ 220 hz 5v with a starting duty cycle of ~ 30% low power and switch to 80% high power.
I scoped the orange wire.
The orange wire sends an alternating status square wave signal back to the keypad to tell the computer if the magnetron is loading up properly or open circuit, which will cause problems if you try to use 2 or more inverters in parallel with the same keypad.
It's not clear on your video, did you use a single turn pickup on the inverter xfmr ?
@@sparkyy0007 I am not sure what you mean when you said " did you use a single turn pickup on the inverter xfmr ?"
@@luckygen1001
The ferrite transformer supplying the work coil, did you just relocate the inverter transformer off the PCB, or is it a matching transformer that you added ?
Can't tell from the video with the inverter cover shield on if you just relocated the transformer to the work coil.
@@sparkyy0007 The original ferrite transformer from the inverter was not big enough to have copper tubing as a secondary winding so I used a ferrite transformer from a crt tv.
glass can actually withstand very high temperatures. The enemy is stress generated by uneven heating. That works every time.
There was uneven heating in the glass jar as the tin was red hot in one place and cool in other places
Would think moisture would be a big part ..
I've wondered if this were possible myself after overhearing a guy talk about making one. Never got the chance to chat him up, so knowing what wattage the microwave is would help the rest of us to know what to look out for while scrapping.
The wattage is written on the front of the microwave.
@@luckygen1001 Ah! I was watching on my phone and must've been distracted when you showed a close up of the control panel. Thanks for the reminder!
@luckygen1001
My uneducated guess is that the reason why Your glass jar didn't shatter is that You managed to heat it "evenly enough". I believe that what makes glass "shatter" are the tension that is built up between areas with "substantially different temperatures", that therefore are expanding to different degrees.
The fact that You had such a comparatively large portion of the jar covered is what I believe "made it work", and I believe that if You for instance had had a taller jar and just had the same size wrapping on the mid section it might well have shattered...
Well anyway thanks for the great content, always interesting.
Best regards.
Your analysis is spot on.
Slow, fairly uniform heating followed by similar cooling will anneal the glass.
Even soda-lime, which reacts poorly to thermal shock. Borosilicate is way better, but NOT perfect; I've blown some up just cooking dinner... :-)
congratulations 👏 great idea 👍👈 success there family
Would it be possible to show the fly back transformer. Cheers
Pewter melts at around 250C, much like solder. Wouldn't it be easier to use a gas heater or blowlamp?
You are missing the point
@@AlphaBobFloridaOverlord OK. What is the point?
I can't seem to remember how to measure frequency with the a.c.volts setting on my multimeter.
Hmmm...
Well I can.
Many have multi function for the switch, like on my Fluke. You go to AC V, turn it to the highest setting if you don't know the range, and hit the freq button.
I would love to try and reproduce this configuration but it would be of great help if you could describe the isolation coil...
I am not sure by what you mean by isolation coil?
@@luckygen1001 the modified flyback transformer
@@karmicmessenger I used the ferrite core from a flyback transformer from a t.v. and used 30 turns for the primary windings and 5 turns for the secondary windings.
Wondering what power or watts were on the output leads?
You are a living legend...I worship you till the day I die...Please keep posting your videos
Luckygen, I have had another look at microwave inverter board that I have. It appears the there is no feedback connection from the secondary side to the primary driver circuitry. As you mention, there is a current transformer in the primary circuitry to monitor the primary drive current . The absence of any feedback connection from the secondary suggests that the board may well continue to operate if the inverter secondary winding was removed altogether. In that case, it may be possible to remove the transformer from the board so as to get rid of the high voltage secondary altogether, and then re-wind the heavy multistrand primary and thereby make room for some turns of the copper pipe as the secondary winding. Indeed, I can see no particular reason why the inverter board would not operate with its power transformer physically removed from the board and just electrically connected by the primary. Either way, winding the copper tube as the secondary would enable you to dispense with the intermediate (ex tv?) flyback transformer core that you have interposed between the inverter and the work coil.
Obviously, the copper tube secondary would have to be adequately insulated from the inverter primary, which is live at our 230 volt mains potential ( no namby pamby 110volts in this neck of the woods). When winding the transformers in pushpull or H-bridge driven inverters, you have to worry about leakage inductance between the primary and secondary windings. That is why the primary and secondary windings in computer power supplies are often split and interleaved to achieve close magnetic coupling. However, in flyback type inverters, such as I believe the microwave inverters are, leakage inductance is not an issue, so you can use plenty of insulation to physically separate and insulate the secondary copper tube winding from the primary. As you would know, It may be possible to improve the performance of your set up by adding capacitance to the work-coil circuit, either in series or parallel with the work coil, to get it closer to resonance at the drive frequency, but that may also risk letting the blue smoke out of the inverter board. The load presented by the work-coil changes dramatically as it is tuned towards resonance. The capacitors have to be able to handle the high current and when connecting smaller capacitors in parallel care has to be taken with the physical and electrical arrangement so that they share the load equally. In other words parasitic inductance in the connection arrangement can cause problems at such frequencies. If you get the idea that I am enthusiastic about your experiment, you would be right.
More power to your right arm! Just make sure it is not 5,000 volt power from that inverter secondary!
I would really like to meet you some day. I suspect that, like me, you are always looking at things and wondering, what else could we do with that? In my case it might have something to do with not having a particularly materially well-off childhood, although I cannot claim that we actually lived in a hole in the road.
By the way, did you find a source of nickel for alloying in your cast iron? I think the best convenient source of a small quantity might be the high nickel welding rods from Bunnings. You can get 25 Bossweld 2.6mm Nickel Arc 98 stick electrodes for A$32.88. Assuming that they are only 300mm long and 98% nickel, that yields about 346 grams of nickel. That works out to be about A$94,700 per tonne or about 4.5 times the bulk nickel price, which is not that expensive for a small quantity. Cheers.
Yes, used microwave ovens have so many uses. Make sure that you
look at my video “ Repurposing a microwave oven controller.” It shows in detail
how it was done. Regarding the microwave oven transformer it should work
disconnected from the inverter PCB. I know that manufacturers do change
settings and parts so what works on one oven may not work on another. You just
have to keep trying. I have avoided use caps on the work coil for two reasons,
1. The output frequency can change a lot when the inverter is under load and
not under load. So a large array of caps are needed suit the changing frequency.
2. Caps in commercial induction furnaces are water cooled so how does one build
a water cooled cap? Have a look at my video showing the inside of a 300Kw power
supply for an induction furnace. Water cooling is used a lot. I think that we
do see things in a similar way. For a long time I never had any interest in
electronics but in the last 20 years that has changed because there is so much
being thrown out and gives me a chance to see if I can reuse or repurpose it. I
will have to look at those welding rods at Bunnings. I was thinking of using
metal plating nickel but with shipping costs it may end up just as expensive as
the nickel welding rods. A long time ago a friend came to visit me and saw the
microwave oven transformers in my shed. He said to take of the top bridging
piece and connect 12 volts to it. I was amazed at how strong the electromagnet
was. One of these days I will have to make video about all the uses for a
microwave oven but if I do some one will watch it and say I can think of 50
more things you have missed.
NO ...Not pathetic demonstration at ALL.... It is a Good Useful One...
Quite interesting, I think you could increase effectiveness by taking advantage of tank circuits. if you can tune the resonance frequency of an Inductor, and capacitor to match that of the power circuit you could manage large power peaks.
Using capacitors to get a higher power factor might be a problem because as the load changes so does the power factor. I would need to have many capacitors of different values to switch over as the load changes. Having the power factor at unity would put more power into the crucible and faster melting times would result.
I think Mr. Carlson should be in on this.
Facinating and slightly scary topic. Ideally I would prefer to remove the high voltage winding altogether - I presume you have just left it in place and open circuit. You have clearly disconnected the HV output from the magnetron so no fear of microwave radiation, just the 5000 volts. I didn't hear mention of your coupling winding - did you add that yourself, wonder where the wire came from. Most inductive heating products sold on ebay have direct coupling between the driver electronics (fets) and the heating coil whereas you are using several stages of transformer coupling. Again, the direct coupling approach uses parallel capacitors to resonate the heater coil with the driver frequency, I note you did not need to do that - would it run better if you did. Pretty good as it is of course.
Nice proof of concept. Fairly simple. That said I have not seen anyone else do that.
Unfortunately I only have one scrap microwave and its the traditional type but if I ever come across an inverter type I will definitely give this a try.
It is a very rare thing to have done something that no one has done. You could try a recycling center to get one.
@@luckygen1001 it is indeed rare to put out an original idea.
I live in the Caribbean. No luck here with recycling centers. Heck I am struggling getting LiPo here. One supplier I found is charging almost $100 for a battery that retails on the net for less than $15. If I import I have to pay a hazardous charge of $85 on top of all other cost including shipping and then tax on that. Probably closer to $175. I refuse to pay that much for battery.
I did a series of videos on solar cells and charging a car battery without a MPPT controller. I went as far on the last video as working out all the efficiencies. That I have not seen anyone else do either.
Thanks! You've helped me work on my prototype.
i wonder if you would end up saving any power if you used this concept to heat up the water in a hot water heating system to heat up a typical small suburban home?
Sorry to disappoint you any any way, but there's not a chance. Induction heating (properly tuned and designed) is at best 80% efficient. A standard resistive heating element is always 100% efficient. You'd end up spending MUCH more on your electricity bill that way. Only exception is when using a induction cooktop for short periods of time, because the pan itself is heated and the cooktop and coil don't need any time to heat up. Long term resistive is still better.
@@theLuigiFan0007Productions I've heard the opposite -please site your source. Even if true, induction heating definitely does have its place in industry where it is excels.
@@mevk1
www.centurylife.org/is-induction-more-efficient-than-electric-coil-or-gas-an-energy-efficiency-comparison-between-stoves/
However, it efficiency does depend heavily on the application. In the case of smelting metal it's more efficient because the metal is heating itself. In most other applications resistive will always win in efficiency, but not speed.
@@theLuigiFan0007Productions That link does not say resistance elements are 100% effecient as you claim. Far from it. It states that professional studies done by the government show induction heating is slightly more efficient. Writer of article did his own study and made his own conclusions. He claims that induction heating is more efficient if cooking time is not too long, but less efficient if cooking takes a long time. Obviously, their is not much efficiency difference between the two methods as you falsely claimed. Interestingly, the latest consumer appliance rage is a combo unit that has two induction burners and two resistance burners so you get both in one unit.
@@mevk1
Sorry for the confusion, I get what you mean now. I was talking about the act of creating heat from energy, not the overall efficiency of any one device. Once you take into account losses transferring heat, say, into a pan, you are right, resistive heating isn't 100% efficient.
The act of converting power to heat was 100% efficient, something induction heating can't do. However, induction heating bypasses the need for heat transfer, thus partially negating the fact not all the input power becomes heat.
For resistive heating, 1W in creates 1W of heat. For inductive it's closer to 1W in, 0.8W heat out. It depends heavily on application which has better overall efficiency. If heat transfer losses when using resistive heating exceed 20% and you're heating metal, inductive wins almost every time in overall efficiency.
I guess the point I'm trying to make is explained by this example. A electric water heater has the elements submerged in the thermal load, so it achieves a very high overall efficiency, usually 90% or better. Inductively heating metal to heat the water would result in a decent drop in efficiency because not all the magnetic field is converted to heat. On the other hand, smelting steel with electric heating would result in great radiative heat losses at those temperatures unless the crucible was near perfectly insulated and very heat conductive. Applying heat from within the metal itself is a whole world better.
TL;DR:
Sorry for confusion.
Heat source efficiency ≠ Overall application efficiency
Does time go faster with inverter microwaves only?
Yes.
Why only an "inverter" microwave? What is different there?
Higher frequency than is available from a mains socket.
@@luckygen1001 yeah but isn't that just higher voltage from a transformer?
@@luckygen1001 but very good job on the ease of increasing voltage by a simple wire wrap on an existing set up if that is all you had to do.
I mean an increasing amperage
@@niktesla3939 that is genious, but I think if you follow that turn of wire, I think it then is soldered to a flyback transformer taken form a discarded TV.
Wow, awesome. Definitely need to be on the look out for these sort of microwaves!
I was expecting the glass to melt. Weird that nothing much happened to it.
It's my first time to see too
Can you melt gold init with bigger wire and bigger fuses?
I will have to try that.
So, how did you seal the exhaust pipe? Where did you get the fitting for your water system, too? You can never get a response from E waste Ben. Have a heap of electronic boards to get rid of. I live in Bendigo.
I used an arc welder to seal the bottom of the exhaust pipe. You can buy the fittings from reece plumbing supplies. Wow you are going to drive from Bendigo to ewaste bens place, the petrol costs are going to eat into your profits big time.
@@luckygen1001 Only when my wife has a medical appointment, mate. There is nowhere to sell boards and cpus here.
Great video! You got me thinking. Generally a dangerous thing..
Mark
My videos are designed to make people think.
We all need a little excitement and adventure from time to time!
@@luckygen1001 And I thank you for that!
The limiting factor here is the power rating of the supply in the microwave. Most large consumer versions are a kilowatt to 1.5 kilowatts. Not enough umph for many metals. But your demonstration of the lower temperature melting metals was very interesting.
@@ginkumpow3726 Yes we do.
As you can see it is limited to low power rating but I was very happy to see it working. This video was some thing different for youtube viewers.
I would like to meet you one on one. How can I contact you? I live in southern Qld. Are you in Qld?
I live in Victoria so if I went to QLD I would be very unpopular with the authorities.
Great video with details & explanations all can understand.
Will stainless steel get hot in this?
It works best with magnetic steels but to heat up non magnetic metals it can cause many problems with the inverter.
I could be wrong, but it seems to me that the fans you have in use are from a computer and I think they are 5.5-volt fans, you mentioned having a 12-volt power supply, so what I think is happening is the fans are being overpowered and that would cause that sound.
They are 12 volt fans driven by a 12 volt power supply.
I like that you are saying not to open a microwave oven if you are not familiar with it. How can someone become familiar with if he cant open it?😂😂
Better to be safe than sorry.
Good job!👍. Have you looked at any of Dr. John Milewskis work on TH-cam using microwaves and magnetite being a susceptor that absorbs the RF and gets hotter and hotter and melts glass?
There was a website long before youtube that mentioned the same things and I tried it and it worked. You can melt metals in a microwave oven by using a crucible that has been coated with a material that will absorb microwaves.
@@luckygen1001 The developed pace of entertainment & content of luckygen's videos is truly artful.
• i am concerned, however, that recyclers will begin leaving behind a glut of *non-inverter* microwave ovens to clutter our alley's & byways
• luckygen, please look into developing useful projects for these ' *other* ' left behind microwave ovens?
- indeed, as summer fruit season approaches, i would really like to put my own oven to better use;
Do you think there might be a way to contain the plasma for use as a grape-plasma powered furnace?
(even if it were fictitious, my finger will *always* hover - ready to click - over anything that involves grapes & plasma)
I would recommend that you consider to make a "High Frequency Capacitor Bank" to back up the one that is mounted on the microwave!!! In that way you can shorten the smelting time and save your self the possibility to have to run around trying to find an other microwave!
So how do you determine what value capacitor should be used?
I want you on my side when the zombie apocalypse hits 😀
Glass breaks when the heated part expands very rapidly relative to the rest of the body. In this case the contact area between the glass and the can was little, and the thermal mass of the can was also not much, and the can was heated slowly. The over all effect was slow heat transfer form the can to the glass and therefore slow expansion. Plus glass jars are a bit heat resistant, they are not like say a flower vase. So all these little effects equal to no breakage. Im no glass expert tho, not at all :)
Oh very cool experiment tho, with successful results luckygen.
I was wondering what the risk of electric shock is from touching the coil and an earth point? I like this project.
Don't touch the coil if it has high voltage going through it. You can use a transformer to lower the secondary voltage to a safe level. I don't think that an earth point can be connected to the coil.
is there a possibility 'at' the induction coil could be radiation in the direct area of it? maybe I'm wrong but it looks like a open electron field.
The steel crucible is absorbing all the power in the coil.
@@luckygen1001 , how about when it's on without anything in the coil? looked like on other videos when they're dipping objects into the coil there's still reading amps and volts?
If you want to destroy this inverter start it up without anything in the coil.
The copper tube coil could short itself with the contact from the exhaust tube crucible ......should the copper heater coil be insulated using fibre glass sleeve ?
Yes the copper coil could short out on steel crucible but I make sure that does not happen. I plan on using ceramic fiber cloth that is 3 mm thick to stop heat loss in the crucible.
@@luckygen1001 ......Thanks for clearing my doubt. Excellent Video and Explained in detail. Really appreciate your work . Thank you once again.
@@luckygen1001 does cloth need to be sealed with hotface of some kind (like ceramic wool does) to prevent airborne hazardous materials? I can't wait to see you melt aluminum, copper and possibly cast iron.
Wow, will preheating via induction reduce yor fuel oil / propane consumption and reduce length of melt.
It also might extend the life of the crucible.
Just thinking.
Less energy maybe, but crucible costs can go up considerably if using small induction with graphite crucibles.
Great work I'm very intrigued! I have made a Tesla coil out of 2 microwaves with the old transformer type. Could you please share any info for the mod that you did to the board? Would be much appreciated. Subscribed cause of this video. Thanks
Bypass the high voltage part and use a crt flyback transformer
@@luckygen1001 Thanks mate much appreciated.
Glass takes a bit of heat to shatter .Most times the shatter is from a fault line that gets heated
Are you sure that 32 reading is frequency ? You have your multimeter selector set on reading voltages not frequency !
I can read frequency by using voltage function and pressing the blue frequency button.
@@luckygen1001 so are you running that inverter at 120 vac or 240 vac? No way an American power supply could boil water that quickly, unless that water started the test at around 180 degrees f. We only have max 15 amps at 120 vac.
After that the breaker trips.
@@markhonea2461 The inverter is running from a 240 volt outlet and the water temperature was at room temperature (20C)before the power was switched on.
@@luckygen1001 thanks mister!👍
That would be an awesome tea kettle.
As well as that it could raise steam in a small boiler for a steam engine.
Hey lucky just having a look when your measuring the frequency output. Is your multimeter on Vac instead of Hz? Just asking in case your reading was 30mv from the inductance or 30kHz
By the way it’s good to see some aussies floating around on the TH-cam’s, really enjoy watching your stuff mate.
You are the second person to ask that question, my meter will read frequency on AC or DC if I push the blue frequency button.
luckygen1001 sorry mate didn’t see that
Thanks for that, plenty of good info in your stuff keep on posting
@@rooey4193 ...Thank God for your Green Signal ! Lol !!!
You are the best
Great presentation style; good video and sound; nicely paced; very good editing; Well Done, Sir!
wow this is neat. could it melt aluminum?
great channel
If you add capitance in secondary of transformer circuit to control power factor might be more efficient .
put in capacitance to balance the inductance of the heating coil, the resonant effects will cause the heating effect to be much stronger
So how do you know what value capacitor to put in to correct the power factor?
@@luckygen1001 you have to know the inductive reactance (2[pi]fL) of the driven coil at the frequency you're using, then you get a capacitor that will have the same reactance (1/(2[pi]fC)) as the coil and that will produce a resonant circuit. Being in resonance also means the power factor is '1' - perfect
@@Gaark Or, trial and error with decent metrology... ;-)
@@Gaark @luckygen1001
:: if you went back to the configuration when the coils are still connected to the microwave & magnetron,
... try a grape fueled plasma furnace !
( just line the bottom with partially-sliced grape halves - 8
LOL!!! you are one crazy dude! Well done!
Hey awesome. Disappointed the details are missing as to the connections that you mentioned for the CRT. Minor detail but as usual awesome. Wayne
Awesome? This was as informative as an ehow video. "take some wires and hook them to the circuit board" Gee thanks, Mr. 1001. Now I will build an atomic bomb with such detailed information. Awesome? No.
So true.
my bet is that inside a thermal refractory it will melt the alu twice as fast. Good experiment.
You should build one and try that out and let me know if it works.
@@luckygen1001 I am working on mine, though I don't know if an arch furnace would be easier to build. But don't hold your breath, I get about 10 minutes of free shop time a month.
As always- excellent! Well done.
The glass was heated evenly, it would have shattered if there had been a temperature gradient across the section.
How about giving us the schematic
did you wrap those induction wires around a beer can?
It was a can of baked beans.
Guaranteed the dude is not marries nor no children. Using, bricks, the dirty jar, tin can, buckets stashed, hoses around with a microwave to build a furnace that needs copper welding. If married with a kid, this project will take a year and abandon half way.
What’s the voltage going through the induction coil ? Worried that you could get a nasty zap
About 20 volts.
What luck, found the only microwave in the world with a high frequency inverter. 😏
There are plenty of them where I live.