Making a Powerful Electro Magnet from a Transformer

[@samsiryani9023]

One main reason I keep enjoying your projects is that you do a great job explaining step by step process involved even in the most basic things. Great job sir.

[@louisbotes337]

Hi thanks for a very informative video. I do however do not agree with your indication of the magnetic path. The magnetic fields will split at the centre pole and flow the the other two faces generated by the cut you made. If you lay the magnet on its side on a piece of paper and energise it lightly and then sprinkle iron filings on the paper the filings will align with the field and you will be able to see where the magnetic path is.But none the less I think it was a cool video and was presented in a very logical manner. Thanks very much Louis

[@ahistoriaseusefeito3191]

Correct,, that's why I enjoyed that project. Good job.

[@jenniferkaltenbach851]

Gardening with electric and magnetic?

[@MarVlog420]

Thanks your information ❤

[@alanpayne1442]

Enjoyable video, I wish my Electrical Engineering tutor at college 60 years ago had, your interesting approach about magnetic flux.

[@HeyChickens]

Not sure if someone has already pointed out this minor detail, but I will go ahead and do so: when he drew the magnetic field lines for the transformer after being cut in half, the field lines should have actually gone from the middle section out towards the two open ends of the transformer at the bottom, not towards the closed end of the transformer on top. The vast majority of the flux goes in and out of the open ends, not the sides or top. You will notice this if you try to stick some iron on the top of the transformer- it will not stick nearly as well as on the open ends at the bottom. Very cool video though, and nice way of illustrating things!

[@samuel-br.man__3571]

Magnet in middle> magnet on-under

[@buckaroundandfindout]

Energy flows in the path of least resistance. Therefore the flux will take the straightest path from the copper the iron core because the air presents higher resistance to the flow or current produced by the power supply. Energies natural state is to 0.

[@HeyChickens]

@@buckaroundandfindout Yes, the magnetic field will avoid going through the air any time it can, but if you put a gap in the path of the magnetic flux like in this case here, it will go through the air. The two ends have one pole, and the center has the other. The magnetic field is trying to complete the circuit between those two poles in the most efficient way possible, therefore it will come off the ends like I described. Any other path would be longer than that.

[@buckaroundandfindout]

@@HeyChickens constructive Central pedal divergence is what you are referring to. Yes some flux lines will flow through the air because there's no room for them in the path of least resistance. Especially in the case of an electromagnet where the force is being pushed into the dielectric field thereby forcing the internal forces to become external. Gaussian flux is introduced to a piece of steel in which it is changed fundamentally on the molecular scale therefore allowing a bypass of the flux fields in what is known as counter space. Where you see the flux in a feral cell is usually the path of least resistance ergo where the force is not located in the flux line. The force is in the space in between the flex lines, that is where you will locate the bulk of the energy that is being displaced via the lack of pathway in least resistance.

[@buckaroundandfindout]

Furthermore magnetic attraction is a little bit of a misnomer as far as the words and language describe the actions. It would be more accurate to say that two pieces of metal rushed to a null point that is a convergence of flux lines in relation to the spin of electrons due to the polarization of rare earth metals. Ergo Force equal to attraction is acceleration to a null point.

[@richardmiller3781]

Grinding, drilling, clamping, mill work, dent pulling, project or heavy material transfer, lock and that is just off the top of my head. Great video

[@raygarafano3633]

Yup , a magnetic chuck.

[@buddymartin7923]

Something about this dude just makes him enjoyable to listen to and learn from.

[@33samogo]

Very impressed👍When testing heavy loads, make sure to insert safety link in both directions (use slightly loose rope), if the magnet fail at 300kg or more, the steel block will hit the car and the magnet can hit you with a great force, be careful!

[@samrodian919]

Yes! Newton's first law of motion comes to mind, "Every action has an equal and opposite reaction". Yo certainly don't want that magnet flying off and hitting your shin, that would break both tib and fib easily

[@timloney2251]

I will use it to load heavy pieces of steel Into my lathe and mill with my jib crane. Awesome video with how to and verification! New subscriber!!

[@1425race]

Great and useful project. I'm a woodworker with a good quality cabinet saw. I use two electro magnets in a wooden feather board to guide my work through the saw instead of using my hand (for obvious reasons), I can position the feather board anywhere on the cast iron table to fit the work I am cutting. I wished I had seen your vid before I purchased the magnets from Aliexpress. Going to build your drill press vice next.

[@StormChasingVideo]

We just had roofers replace the shingles on our roof and I was thinking of how I could pick up all the nails that where left behind. Something like this with a lite weight battery on wheels to go over the ground and rip all the nails and metal from the soil would be perfect.

[@jonmiguel]

Put different sized nails into different types of soft and hard woods at different depths and see if you can devise a practical electromagnetic nail puller.

[@asfdasdful]

yooooooooooooooooooooooooo

[@pimpjetfighter05]

This

[@xx0xxxx0xx72]

Nails have so little surface area for the magnet to lock onto, it would be virtually impossible to devise an electromagnetic field (out of a microwave transformer anyways) capable of pulling a nail out of wood, especially hard wood...

[@skysurferuk]

Everyone else on the planet would've drawn the magnet on the whiteboard with North on top. Not a Kiwi!.. Great vid, long time sub. Keep 'em coming!

[@mvnar]

hmm.....like this is as if a great suggestion 😅

[@skysurferuk]

@@mvnar What?

[@kingmanazgold6233]

Very informative video and it gave me great info on which type of voltage/current to use. Here's a project that I'm starting to work on. I go prospecting for gold out here in Arizona and we have a lot of " black sand " in our good paydirt. I'm taking a 4" pvc pipe and going to tape/strap 2 of these on either side to pour the dirt through so the magnetic field will "stick" the magnatite ( black sand ) to the sides and let to paydirt fall through for further processing. Challenge is to build one of these and post a video. Thanks again and I'll post pics when I'm done.

[@samrodian919]

Good luck with that I'd love to see that project working !

[@LawsForever]

A very good combination of theory and application, well done! One thing though: with a cut up transformer, the vast majority of the magnetic field lines go from the center bar to the side poles, not around the transformer (9:32). That's what causes the field loops to be closed when an metal object goes across.

[@covodex516]

wow, i had not expected that strength with only a bench power supply. I was thinking about making a big electromagnet from scratch but when you can just grind away the weld on an MOT to have a super good one at hand, that'll serve me a lot of work.

[@lysdexic5205]

I've watched two videos on magnetic vices. One created a "magnetic table" that holds the work with the vice mechanically attached to the table. The other used the magnet to hold a traditional type vice to the table. Both have advantages. If you want to get really creative you could try removing the other side of the core as well and see if the drill press table would work as one side of the core making a magnetically held magnetic table. 😎

[@stevengouws8684]

Keep reducing the power supply to the magnet ( volts and amps equally ) to see at what point it fails at 300 kg's, then find your wattage from that and divide it by 300 kg's to see your watt strength in Kk's lifting power. Great video, well made and informative, would never have guessed that a low resistance in the system would make such a difference.

[@gary6570]

Best explanation on KZbin! Love the Brit speak. Bob's your uncle!

[@dougpine4746]

That's a surprising amount of holding strength for such a small magnet. Maybe it could be used with cart type frame for a rolling gantry to move things around.

[@headbanger1428]

I’ve seen loads of videos on microwave transformers converted to spot welding transformers, but this is the first time I’ve seen a conversion into an electromagnet. Nice work! 👍 I’ll give it a try myself.

[@raymondgarafano8604]

Yup, a storm's power surge took out my microzappr, I knew there was a good size transformer in it and cut two groves with an angle grinder. Having an old truck battery with external cell connectors, I can use at 6 or 8 volts and not overheat the primary coil.

[@headbanger1428]

@@raymondgarafano8604 I could not find microzappr online. What is that?

[@raymondgarafano8604]

@@headbanger1428 a microzapper is just another term I use for a microwave oven, that's all, Maybe I should have called it a micro-doo-hickey, a micro thing-a-ma-jig.

[@โนรีคอกเบิร์น]

There have been dozens of copies all the same for years. Pathetic.

[@headbanger1428]

@@โนรีคอกเบิร์น Replies little man to a comment of 3y ago when there wasn’t.

[@jeremyanderson2843]

Love the way you explain what your doing !

[@marksstudio]

Dude your channel is terrific and I had to subscribe, and that would be perfect for a surface grinder application.

[@sibalogh]

E-magnets are better for reaping/tearing uses than for lateral/sheering. Just think of those permanent magnet pickup clamps; when you turn them off you basically rotating the load to short the poles...

[@markg1051]

Wow, very impressive cuzzy bro! Just one bit of feedback and maybe someone else has already pointed this out, don't have enough time to read through all the comments. That is in your explanation of the magnetic field path in the cut core, you've got it going from the center limb to the back of the core when in reality it is the same path as in the uncut transformer, via the left and right limbs of the core. You can confirm this by checking the magnetic strength at the back of the core and you will see that it is just as weak or very close to that around the uncut core. 300kg plus, holly sh....t! Keep 'em coming, great video and very enlightening. Cheers and stay well from across the pond.

[@JDFARM]

You could make an electromagnetic door lock. Also, the reason I am studying magnetics is to make a large magnetic lift for scrap metal. I think you very much for the ideas I have taken from your videos. Great job.

[@balloney2175]

This video must have million subscribers already... it is very informative!

[@MiracleMAX]

Good to see that I am not the only one obsessed with magnets! I couldn't help myself - I made a video on my channel several years ago. You have given me a few more ideas...... I have several microwave transformers that might be taking on a little transformation themselves 😁 Next term I will be teaching night classes on automotive electrical subjects. I drag around a rolling trolley with heaps of wire and you guessed it.....lots of permanent magnets as well as electromagnets to show students how solenoids, motors, relays and other tricky electrical components work. I usually use a rotor out of an alternator as an electromagnet to show magnetic strength holding a solid shaft of steel, but your idea might be a good alternative (excuse the pun) option! Keep up the good work! 👍 G'day from 'Across The Ditch' MiracleMAX

[@martinlicht1969]

Nice, use to lift megalithic blocks in chain out of a quarry the way Ed might have , seriously, it is amazing for the current used.

[@yeshecan7]

Really...you do have very professional welding skill. Thank GOD ....yes you do have! 😇

[@zebulonmann82]

Awesome video I enjoyed it… hopefully everything is cool down there in New Zealand looks like you guys are on lockdown over one single case! No deaths! Better days ahead ❤️

[@jjb1974]

very cool. so small yet so powerful. I made an electromagnet using a 65-pound steel bar and about two hundred feet of insulated copper wire. then hooked it up to a 12-volt deep cycle battery. it was strong, but not as strong as that little one you made. And it got hot quick. Thanks for the perspective. Ill change my design. ; )

[@petersack5074]

good boy.....same as i use...angle grinder/chop off saw (homemade from furnace motor, and microswitches from microwave).....to re-create MOTs for chargers, welders, etc. made an 18 volt dc supply for cordless tools, converted to corded tools, ...mots rewound for 19 volts dc with capacitors and bridge rectifier.....all work wonderfull....good for you...

[@randomelectronicsanddispla1765]

Something of note that could be relevant. Magnetic field is proportional to amperage times number of turns (plus or minus difference of losses) A 200 turns at 4A electromagnet will have almost the same strength as a 400 turns 2A one. Only case by case differences will make one or the other slightly stronger. Well, there are other factors to take in consideration when choosing one over the other, such as power loss into heat, thermal properties,... but that is more relevant when winding an electromagnet from scratch. The point here is to use easily available material and minimum complexity of modification. Which microwave transformers fit perfectly, plentiful, cheap and easy to power.

[@danielbuckner2167]

If you don't mind a question: how can i determine the max or correct amperage to run thorough a primary winding? Can i use the labeled values on the transformer? I also have a question about height of the legs on the "E" frame the windings are in. Is there a sweet spot in relation to the ark of the magnetic field for an increased gauss value or just closer is better? Lastly since the magnetic field is the same at each pole can I use plates on the side and leave both poles ooen to have the ability to hold items on top as well as hold the device down to a metal surface as needed for a drill press? Thanks in advance for any illumination you might care to offer.

[@Paradoxical_heuer]

Your experiments flow just as i would do them myself, thanks for the detours

[@theoyanto]

Great ... The pulling power was truly amazing

[@jeandeverchin8774]

Magnifique Monsieur. Merci pour la vidéo.

[@Doggmatt]

Great video, excellent descriptions! I'm wanting to build a trommel with an electromagnet Incorporated at some point to remove nails from wood ash. Thank you for posting!!!

[@jaymakormik6779]

Thanks ,guy. Thats a cool idea about an electric vice block,like a workbench that holds things still while you're working. You should patent it(fast)!!😉

[@charly4594]

Excellent demonstration of exactly the kind of info on electro-magnets that I was looking for. Thank You! I will be watching if you decide to utilize AC power in demo and it will be interesting to see the pro's and con's of DC vs AC with powerful electro=magnets.

[@beachinrc101]

That really helps me understand how magnetic power works thanks for the great vid 👍🏼

[@kreynolds1123]

In other words a transformer core contains all the field, as long as the core isn't saturated. Thus external iron doesnt interact with the magnetic fields inside the core. But where the field exits the transformer core, they can interact with external ferus metal.

[@subramanianr7206]

The field lines are are in a close circuit. The horse shoe magnets would be having pole pieces when stored for long time. The torroid core design assures self shielding meaning any other torroid core transformer can be placed just beyond half the diameter distance of the bigger one. In the case of a solenoid winding to minimize/ avoid interaction the coils would be placed perpendicular to each other and in the case of a third coil, it would be placed in the vertical plane. You can observe this in the radio circuits.

[@kreynolds1123]

@@subramanianr7206 if one rewatches the video 5:14 , the original core before being modified was expelling some magnetic fields. That's indicates over saturation that inturn indicats one should run fewer amps due to the fact that the rate of increase in the magnetic field drops due to drop in a decrease in permibility. en.m.wikipedia.org/wiki/File:Permeability_of_ferromagnet_by_Zureks.svg But, on rexamination of transformer design, i might be wrong on the saturation current after the core was modified. Transformer design sometimes introduce an air gap to increase the saturation current level. Cuting the core in half introduces a large air gap in the magnetic circuit. Presumptively, that will also increase the saturation current level, maybe well beyond 4 amps. The large air gap now allows for using the core as an electronagnet. But when a piece of metal closes the air gap, the saturating current level will drop. Take away is that there are more things to consider what current one wants to run depending on the core and how one will use it.

[@oscar3611]

Great video man! You clearly put a lot of effort in it, and it shows. It would be a great electronic lock for your workshop. Not at max current, that would be too harsh for the winding. Or if you make it waterproof, it could be a great magnet-fishing device. Power it up with a car battery. And I sure can use a scaled-down version to get the thousands of tiny screws and bolts out of my long fibre carpet.

[@tcellen2136]

great explanation. Wish I had you when doing my apprenticeship. Got there in the end haha. Looks like you could have used an electromagnet drill vice at 6:19... What about an electromagnetic drill press bed so you don't have to use a vice at all. Still looking for something similar for aluminium too...still looking

[@PM17E5]

Great video, good narration and not annoying like some. I came here with the same idea you had, of making an electromagnet vice :).

[@adelataei8785]

Woooow!!!!thats awesome!! That was completely counterintuitive for me.thank you sir.i want to try it with circle core.

[@raviduprasanna6401]

woow Bryman i really happy see all hobbyist engineers using over expensive flukes

[@SitudewageGemunujayasing-zd5yx]

Very informative video . Sir , thank you so much for sharing your knowledge . I am from Sri Lanka .

[@dumbingitdowninareallycomp2830]

Big with ups to you for this education , thanks heaps. Your education skills are great with your presentation with details the most important. thanks

[@musterionsurly]

I'll never look at an old microwave the same again, thanks.

[@siggyretburns7523]

So what if you replace the secondary coil with another primary coil in an MOT? You would eliminate having to chop off half of the block, but would it double the power? And would you connect the two coils in series or parallel? And would you reverse polarity on one of the coils? Would it matter in AC, DC? Sorry about all the questions. 😂

[@blueaxe71]

Well I know you can't reverse polarity on one of the the coils, you def want the same, but that a good Idea if you have 2 of the same broken microwaves. Lol. Not sure if parallel or series would create a stronger magnetic pull. Im thhinkin series cause more amps

[@codyramos3200]

I had the same question couple weeks ago... after cutting a mot into the E shape I placed another coil on top of the primary coil.. connected 2nd coil to the leads of primary flipped the switch and POW!! i thought fk it blew up .. then simultaneously heard a loud thud and something hit the top of my right shoulder... the 2nd coil I placed on the primary coil shot straight up off the mot transformer.. broke the wires off itself as it headed for the ceiling.... I was dumbfounded to say the least ..

[@siggyretburns7523]

@@codyramos3200 I knew there would be polarity issues, but didnt think about the power involved if connected north to north. Yeah, i guess it would do something like that. Did you try reversing the wires?

[@codyramos3200]

@@siggyretburns7523 uh I can't say if I did ... I soldered 1 end of the 2nd coil to another coil to make 1 large coil to work as a secondary coil for a step up transformer... it takes a ridiculous amount of wire to go from 110v to 550v ..

[@Dennis-mq6or]

You can double the range of your measuring instrument by using a simple tool called a 'snatch block' which consists of a single pulley, You will have to move the cable running thru the snatch block twice as far as you would be moving the load, but you would only be using half as much force to move it. Just measure that force and multiply by 2 to double the measurement range of your instrument.

[@โนรีคอกเบิร์น]

That would overcurrent his peabrain.

[@miken7629]

You can limit the current, from an AC source, by using use an AC capacitor, on the hot AC lead of primary, and using the Capacitor Reactance Formula to calculate in Ohms.

[@OtherDalfite]

AC cannot be used to run a electromagnet. Maybe not what you're saying, but the more you know

[@miken7629]

@@OtherDalfite Wasn't what I was saying. I assumed you would use a rectifier, but, before it gets to the rectifier, you can limit the current using a capacitor on the hot AC lead using capacitor reactance formula. Example: 108 UF capacitor limits the current due to Capacitor Reactance Capacitor Reactance = 1 / (2 * PI * Frequency * UF / 1000000) EX: 1 / (2 * 3.14 * 60 * 108/1000000) = 24.57 Ohms 120 VAC / 24.57 OHMS = 4.88 Amps

[@paddler3d]

I want an electromagnetic roller sweep that could just rip nails and screws (as well as other other items with iron in them) out the yard and flower beds of homes during and after a construction project. Something that was strong enough it could pull a 3-1/8" #10 screw out of earth that had been trampled on.

[@iamwillwatson7529]

+ 1 vote for next video to make a magnetic chuck or vise!

[@JaceN3D]

😃 he did it

[@manla8397]

9:19 the magnetic field lines are wrong. Only the cut part will expose the field lines.

[@byronwatkins2565]

The field lines will still VERY MUCH prefer to be inside the iron so the south pole should be extended to all of the remaining iron. The field lines in air will simply jump the gaps from the central exposed iron to the two ends. From there they will be inside the iron for the rest of the loop. Also, in truth, the poles are only at the end surface; inside the iron the magnetic domains realign to cancel the field almost completely.

[@gokhangunay4345]

Indeed, big majority of the magnetic flux will prefer the magnetic core while there will be negligible leaking flux through the air.

[@mvnar]

don't bother about the lines just try understanding his effort.

[@ALIENMACHINES]

Your video is great, you don’t just explain things really well but you jump in with everyday practical experiments we could all do. That is really powerful and to think it came from an old microwave transformer too, I will use this on my own project, thanks

[@kreynolds1123]

Speaking of saturation. Seeing the core expelling some magnetic field at 4 amps means 4 amps is too much magnetic field for the core and you have saturated it. You should have dialed the voltage down to push less current through until your under saturation point. Then you can cut open the core. Pushing more current passed saturation does little to add to the magnetic field past saturation. Thus the extra current does little more than create heat and unessesarily waste energy. (Added after have posting to include new information and avoid confusion) sometime Transformer designs include an air gap to increase the point where current saturates the core. That said, cutting the core in half introduces a large air gap which could presumptivly push up the point where current saturates the core to well beyond 4 amps, but if one closes the air gap with a ferrous metal, it will lower the saturation current again. Takeaways: There are more things to consider when determining what is the ideal current for a given core and how one intends on using it.

[@gar99504]

The commercial magnetic bending brakes are using 220 volt electro magnets generating 6 tons force spread out over 48 inches to secure material. Would like to see what you could come up with!

[@Amit-sp4qm]

Thanks, can you give links for more info in these brakes? More abt the winding and core sizes ..

[@taylortingey4035]

I’m looking at building a system for our Jib crane at work to act on a switch to act as a brake system to hold the trolley in place (to a point) and possibly the swing

[@arthursimon4246]

Thank you for making this video, very interesting indeed. It would be wonderful to know the maximum weight your powerful magnet can carry.

[@vernhartjr]

Make a portable wheeled card electromagnet for wheeling over the yard to pick up miscellaneous screws and nails. It'd be cool to make one for separating black sand from the other sand.

[@nilton61]

MMF is measured in ampereturns. Thinner Wire equals more turns so the heat developed is independent of the Wire thickness

[@raygarafano3633]

I thought u were a Brit but saying 'Bob's ur uncle' confirmed it. U do a great job!

[@TheIdeasGuy]

His accent is definitely New Zealand, not British. ‘Bob’s your uncle’ is regularly used in lots of countries, including here in Australia.

[@joejane9977]

thank you for not blaring music thru-out video wonderful explanations

[@mabul513]

If cutting 2 slots and leaving it full size better than cutting it down as all clips shown? More iron larger surface area? Slots cut also would be nice flat and more iron to stick to.

[@Goodwill345]

Wow you are amazing, great channel for R&D

[@studentofscience]

solid metal will be stronger the laments are there for AC current to eliminate eddy current. the more turns the stronger the magnet will be, to keep the voltage down you can rap the wire by double or more. because there is no magnetic field fluctuations you don't have to worry about eddy currents or induced back voltage so your wattage will remain low. great video.

[@0truckmafk]

@9:12 are you saying that the magnetic waves can be compressed and contained in the case and essentially shielded?

[@das250250]

You could put half the current through the magnet and assess the break strength there , or a 1/4

[@knutkleven5939]

Different steels have different magnetic saturation points, where the magnetic forces pulling towards the iron core is drastically reduced per amp going through the windings. If this point was reached at say 80% current draw of what he is drawing in this video, and then half the current to take a measurement. you only had a 20% drop in magnetic force but half the current draw, thus giving a false measurement. (These numbers are straight out of my ass, and only to prove a point)

[@kenord3437]

Damn great video mate, I will now experiment on how to use this in my workshop and for teaching, many thanks, cheers.

[@pierremorissette]

Thank you for not using loud annoying music.

[@pierremorissette]

I mean just like that is ok

[@josecarlospoggian5460]

Thanks for your lessons!!Congrats from Aussie! 👏👏

[@ahistoriaseusefeito3191]

Amazing!👏👏 good job. You explained very well. Keep doing...your good job...

[@omsingharjit]

18:22 it was coincidence that i was playing with open MOT with 12 Volt 5 amp smps yesterday without I part on it , but Now when KZbin recommend me your video and when i saw that pulling power at juts 5amp i stated this experiment while watching this video 4:00am ( during my sleeping time ) because Mot and smps was laying below my bed I am surprised so powerful

[@stevecann3394]

Amazingly well explained and demonstrated, thank you, many questions answered!! Try magnet fishing!!

[@byronwatkins2565]

The magnetic field is proportional to the number of turns times the current. Since you are using DC, the larger number of turns in the fine wire coils would have needed less stress on your power supply.

[@Prometheus720]

Yes but it is also proportional to the current IIRC. So if he was able to increase current more than he was able to increase turns, this was the way to go. His risk on going to small turns was that he would have to lower current to avoid overheating

[@Patriarchtech]

I love your channel. You are good at explaining things. Also I love your accent and sense of humor. Keep up the good work!

[@terry9223]

Excellent video particularly on ease of selection of the transformer. A very cheap mag drill is in my mind I always wanted, and, what I really want to do is a cheap method to have a kill switch on my digger I need to be activated by trips for safety where the "real thing" dam near costs more than the machine. (the magnet will hold the fuel shut off open and another can similarly lock my hydraulics simultaneously on the same electric circuit). Thinking that much power would also work as a lock on the slew control (it's the real one that kills people tripping or catching clothing) in a circuit where if it's not locked the fuel and hydraulic one power off). Been trying to find a way to do this for ages.

[@HeinrichsMade]

Great video! Very informative and helpful. 👍

[@teddysoft]

Thanks for going thru the steps with a slow/easy understanding informativ learning 💪

[@colvardfamilymobilemechani2095]

Your welds r awesome I loved the video thank u Sir

[@petermines3575]

The ideas are endless so many possibilities

[@shawncalderon4950]

This man is a treasure!

[@asakayosapro]

A common use of MOTs repurposed this way is to create a magnetic drill press base that can instantly be attached and detached from any ferrous / iron / steel workpiece of decent thickness at the flick of a switch. Retail units run pretty high up in the price range just for that functionality alone. The second popular option is a machinist electromagnetic vise it chuck, more often than not is used with a surface grinder, followed by a milling machine for workpieces that can't be held down properly with any other means. While switchable permanent magnet versions do exist, they have their own drawbacks and quirks. My primary problem is figuring out a decent rectified DC volt+amp combination for the MOT electromagnetic coil, preferably something that can be derived from outlet power, most likely from a switched mode DC power brick with current limiting.

[@omsingharjit]

9:21 nope instead it have to travel just to the outer side of the E core because it's the closest magnetic path

[@mekuranda]

I didn't see any comments about the mistake in diagram @9.21 I am confident this is secondary school science stuff....and unless I missed the reference to a basic magnetics concept...i.e. no mention of ampere turns vs flux density ... Schematix is testing you....and you didn't pass!....fun use for a microwave tranny though....and what degradation in lift performance if the legs of the core was left as it was initially cut with angle grinder...as I suspect that not that many have a metal cutting band saw ? Thanks for the great idea and future project !

[@subramanianr7206]

The diagram at 9.21 is absolutely correct. If you want to find out a mistake it would be that he had not marked the arrows on the lines to represent the direction of the convention; but surely he was drawing it from the N pole to the S pole. In the whole transformer the field lines are closed. When the pole piece is exposed by cutting off it keeps attracting the iron with a heavy force. You should refresh your school physics, I believe.

[@mekuranda]

@@subramanianr7206 The diagram shows lines of flux without any effect of the core. Are you saying that the core has no impact on the concentration of flux? If so then I suggest I am not the one who needs to refresh school physics!

[@TigerCarpenter]

very impressed! I was getting worried that we were close to find out what the weakest link of this setup was rather than the electromagnet strength itself. it might have snapped and smashed the car or fly in the air at random. great demonstration!

[@petervogl2379]

Very nice video. Many thanks for that. But it contains two fundamental errors that should not be allowed to stand if you take it physically accurate: 1) You said the strength of the magnetic field depends on the strength of the current. This is correct, but only half the truth. In fact, the magnetic field strength and the resulting magnetic flux depend on the product of the number of turns and the amperage, which is also given as ampere-turns in the data sheets for transformer sheet metals. This means that you can generate the same magnetic field strength with one turn at one ampere or with 2 turns at 0.5 amperes. (Or 4 turns at 0.25 amperes, etc.) This applies until the iron core reaches magnetic saturation, i.e. the "Weiss districts" shown at the beginning are all completely aligned, which is the case at around 1.6 Tesla, depending on the type of core laminations. In addition, a further increase in the ampere-turn ratio does not result in any significant increase in the magnetic field, because the field lines then no longer run in the core but as a stray field outside the core. 2) And this brings us to your second error at 9:30. The field lines shown always take the shortest path from the north pole to the south pole of the metal core. Assuming the north pole were in the center, the field lines would theoretically take the shortest path to the two legs on the left and right which represent two splittet soutpoles and not take the detour through the air around the core as in your drawing. This is because the iron core conducts magnetic flow aprox. 15000 times better than air or vacuum. (again as long the iron core is not completely saturated) However, the field lines in the open "E-core" do not run in a straight line to the two legs, as the corners of the poles (where the shortest air path would be) very quickly become saturated and the remaining field lines are now forced to enter more and more towards the center of the pole plates, thereby describing approximately two semicircles from the inner pole to the outer poles. The magnetic flux through the E-shaped core and the air in front of it therefore result in the shape of a horizontal "B" in your drawing. By the way, magnetic field lines are lazy dogs. Before they take the difficult journey through the air, they prefer to pull on the heavy iron double-T beam and hold it tight like crazy. This explains the enormous holding force in a simple way, without going into physics any further ;-)

[@mattman8685]

Best electromagnet video ever!!!! Damn good work!

[@JerroldGraham]

Great information Mate!

[@gasnmandel4678]

I want to know to how extent can the coil withstand the heat generated in it? great great your effort

[@mikehunt8563]

Thank you for this informative video ! I surly could use the electromagnet that you demonstrated, to pull dents out in autobody applications ! The setup that you have would help me GREATLY in repairing my truck !

[@dolphincliffs8864]

Won't work. It will saturate.

[@raygarafano3633]

Yup a microwave xfrmr works great.12 volts d.c. from a motorbike battery will work fine. Use a few 1157 auto lamps in parallel to limit current. They draw 2.25 amps,with both filaments wrkg.

[@andrewnicholas4829]

Great stuff. Electro-Vise. Gonna Build One Thanks.

[@ellsworth5841]

Excellent. This was fun. Two questions: 1. Why 0.5 to 2.0[ohms]? Is it ONLY about what resistance across the fixed DC source voltage which allows the desired peak current? 2. What type of supply was used in the second (car tow hitch vs. steel pole) test? Was this also an adjustable bench top supply, but with higher current capability? 3. What happens if you hook the coil leads to an AC source, eg. a 120[v] (rms) from the wall plug? OK, that was three questions. Thanks again. Very educational.

[@TJJewett]

This may reveal what a slob I am, but I would use it to pick up random nails, and staples off of the shop floor, or in the field whenver I drop staples while putting up fence. Awesome project!

[@davidgillies620]

There's more than a few mag chuck builds out there using transformers just like this. They usually involve ganging three or four in a box and then potting them with epoxy. The surface can then be ground flat with a surface grinder and used with that very same grinder, or a mill. Another one that sprung to mind was a mag brake for a lathe. An interrupted annulus of aluminium on the headstock (you don't want a shorted turn; that would be bad) would generate quite a lot of Lenz's Law braking force. And of course if rather than cutting the yoke in half you replace the other winding with a few turns of, say, 6mm dia insulated cable you can get some hefty currents: enough to make a spot welder, for example.

[@janami-dharmam]

Even if you do not cut off the yoke in half, there will be no significant reduction of the magnetic effect (holding force). Also, the total magnetic flux depends on the product of the current and the number of turns (N.I) and if you use thinner wire, you can accommodate more number of turns and can get the same effect at less current (may need higher voltage).

[@subramanianr7206]

@@janami-dharmam He has to cut it short. The field strength is going to decrease as the square of the distance Power is going to be almost the same in an ideal set up. That's the product of volt and current is the same in all its theoretical form.

[@janami-dharmam]

@@subramanianr7206 You are wrong; most of the flux will be passing though the core and the field strength at the tip of the iron slab (before and after cut-off) is not going to be much different. The magnetic poles will be located slightly inside the iron in both cases.

[@subramanianr7206]

@@janami-dharmam Inverse square law is a function of the geometry of the space itself. It's a fundamental understanding.

[@janami-dharmam]

@@subramanianr7206 Study and you can learn. For a point source, the inverse square law applies. If the source in a line, the field goes as 1/r and if the source is an extended plane, the field is independent of the distance.

[@dog68north36]

You could use your microwave electromagnet for the base magnet in a mercury vortex drive; so, you can vary the field strength and direction giving you additional control over the vortexes rotation.

[@markcollard9326]

no

[@Hamid-az]

Hi. Good video ❤. I think you can make a drilling machine with this magnet on the bottom . A movement able drill with DC current.

[@rodstouffer8405]

Though difficult to measure the absolute force, I would like to see the performance of two equal EM's, one with a timed momentary current supply mounted stationary above the other mounted atop a piston connected to a crankshaft with a momentary, timed commentator current supply. The crank mounting apparatus (block) and stationary (head) mounts of aluminum so as to not interfere with magnetic fields. Ideally, the timing and supply current electronically controlled with opposing currents supplied at the top dead center (TDC) of piston travel. Once in motion, supply current can easily be generated from the resulting crank rotation or through pick-up coils in the cylinder walls. In theory, the instantaneous opposing magnetic fields of the magnets could produce a force, however marginal, similar to that of internal combustion. Furthermore, this force could be produced on every rotation rather than the 4 to 1 of a gas engine. Obviously some engineering to work out, but feasible, don't you think?

[@australianbloke3934]

Love your videos. Today I started a project to build a tape demagnetiser for old Video8 tapes, audio cassettes and reel to reel tapes. I found a good looking design and tutorial online that repurposed a Microwave transformer. I found a 240 volt LG Microwave oven with a primary winding rated at about 9 amps and pulled out the transformer and micro-switches. After removing the secondary winding as you have done I was left with the primary winding intact which I tapped up to be flush with the top of the core face like your electromagnet. My question is, I cannot get any DC resistance reading on the coil, not even .01 ohms. I cannot see any damage to the coil causing a short. I wired the coil in series with a 40watt incandescent globe which turned on normally, (not a good sign I think) I'm nervous about putting 240V across the coil in case it is indeed shorted. I suppose I could put a variac in front of the coil as well as an isolating transformer (I have a 1KVA ISO transformer) to help upsetting other electronic equipment if it violently trips my RCD. My other option is to wind a new coil. What do you think?