BEST Microwave Oven Transformer-MOT Rewinding Tutorial

[@edpontiff8448]

Thanks for making a video with clear instructions and voice without loud distracting stupid music !

[@electronicsNmore]

You're welcome Ed! Be sure to check out the very wide range of videos on my channel, and most importantly share my YT channel with others. Thanks kzbin.infoc/playlists

[@robertfreeman7798]

I noticed that you were using a carpenters chisel ; I used a mechanics chisel and things didn't go as smooth. I had a time getting the winding out ! I ended up putting the transformer in a vise and just hammering away at the coils with a punch. After about two hours, I finally got it cleaned out. So, thats why I came back to watch your video ! Nice Job ! Like all of your videos ! Thanks !

[@salahoua1]

Despite what others have said about the video I give a thumb up. You made everything very simple and to the point. For me it doesn't matter where and what material you're working with. What matters is what knowledge I get from it. Thank you for keeping everything down to earth!

[@electronicsNmore]

Glad you enjoyed the video!

[@ClagwellsGarage]

After watching this, I am impressed with your speedy system of MOT modification without separating the core. This made for a relatively quiet filament power source for my VTTC. Thanks for posting.

[@electronicsNmore]

Glad you enjoyed the video!

[@MattsAwesomeStuff]

Well that's a bit harsh. I worked hard on mine. I guess I'll just go remove them then....

[@electronicsNmore]

clagwell: Thank you for the kind remarks. MattsAwesomeStuff: I see you also put together a few videos, which I could see you put a lot of time into. Good Job. My latest video showing a step up/step down MOT conversion: DIY Custom Power Transformers

[@ClagwellsGarage]

MattsAwesomeStuff Both tutorials are great for their individual respective purposes. My remark was harsh and unduly all-encompassing and I have amended it. My apologies Matt. For reference, my original remark read as follows: "After watching this, its clear that all other MOT rewinding tutorials should be deleted. Excellent tutorial! Thanks for posting."

[@MattsAwesomeStuff]

clagwell Obviously your statements were made with humorous hyperbole. Mine were made with mock seriousness. Carry on :p

[@barthchris1]

I've rewound a lot of MOT's. If you have access to a stick welder, I've found that its much easier to use a Dremel with a carbide cutting disc to cut along the weld that holds the laminations together. Usually, you can cut the weld on one side and wedge a flat screwdriver in the cut to pry apart the "top" of the transformer. After the "top" is off the windings will just slip out. When you're done rewinding, if you have a stick welder it's easy to put back together. Believe it or not, I've actually had success using a 150W soldering iron and solder it back together most won't have an iron that big though. When I have kept the laminations intact, a tool that makes short work of cutting the secondary is a oscillating saw, sometimes called a Fein tool. it makes a very clean, mess free cut and usually you can just push the leftovers out with your finger.

[@adammcalpine231]

+Chris Barth i'm in a college dorm, so welding will definitely be out of the question. Would it be possible to clamp the top back on and fill the groove with a good epoxy?

[@barthchris1]

I wouldn't trust epoxy or JB weld to work well enough for a permanent hold, there is a lot of vibration and heat when running these that will probably cause the bond to fail. I've used clamps to hold the X fmr together while energized after rewinding. It worked well, it just a little unwieldy. I've used C-clamps and the quick squeeze/sliding bar type clamps to hold it together.

[@barthchris1]

+Chris Barth One more thing, after removing the secondary coil and before rewinding, its a good idea to make sure that the iron laminations are insulated. You can use the existing wax type paper for insulation but it may not be enough. I use Kapton tape and wrap it around any exposed areas, Kapton tape can take a tremendous amount of heat, you wont find it in stores though, Amazon or Ebay has it cheap. Electrical tape is a poor choice because it will likely loosed/sag because of the heat build up if you're running it hard or for extended periods without a lot of active cooling.

[@JosephFernandes2017]

U r Excellent Teacher. I will rebuilt following your instructions. Thank you so much.

[@electronicsNmore]

Thanks for the nice comment Joe! Good luck with your transformer. Be sure to rate thumbs up, subscribe, and share my YT channel with others.

[@efdalkargin1518]

İ watched many videos but i didnt learn information as much as your video even i dont have a good english😁Thank u

[@electronicsNmore]

You're welcome! Be sure to rate thumbs up, share my channel with others, subscribe, and check out my extensive video playlists.

[@va4567891]

Very good information given in the video. Many thanks!!!

[@keithnoneya]

Nice video, the best hand held meter in the world for electronic repair is the one in your hand. The Wavetek 27XT, I've had mine for over 16 years and use it almost daily at my electronics job. Shame they don't make it anymore. Anyways nice video.

[@electronicsNmore]

+Keith Noneya Thanks Keith. I bought mine in the late 90's for around $120. Check out my recent reflow video. I swapped out an IC in my Wavetek.

[@keithnoneya]

+electronicsNmore Cool send me a link or the title i'll check it out. Keith

[@electronicsNmore]

Keith Noneya kzbin.info/www/bejne/j3nGZJlmo7V4fNE

[@electronicsNmore]

It is CRITICAL that the two transformers are wound the same way to be connected in series. If one is wound "In Phase" (Same Direction as Primary)and the other is wound "Out of Phase". then the two in series will not work. If you wind one "Out of Phase, NOT in the same direction, 180 Deg off, Then you MUST wind the other transformer also "Out of Phase" to be able to connect them in series.If You have 1 MOT Primary wound opposite from the other, you can correct this by winding 1 MOT Out of Phase

[@rtdsfgsdfgsdfg]

best transformer instructions. thankyou

[@robertfreeman7798]

Other info. I researched is that these mot have shunts; I didn't find any as I noticed you didn't either after watching your video. Thanks !

[@99frofro]

Probably the easiest way to remove the sec. In the past I've used an angle grinder, slotted drivers, and a rubber mallet to remove both the primary and secondary....reusing the primary, winding a low voltage sec.....like you've done here. Twice I've had to 'roll my own' primaries. Not very efficient but neither is the stock transformer. You can do a lot of fun (inefficient) things with these.

[@mechmania8450]

I want to tell you that if you apply mains to the high voltage winding you can then get 50v ac out of the old 250v winding without doing any taking to pieces. You should know that taking out the shunt core reduces the inductance and the mains winding then takes a lot of current and the transformer will get very hot even with no load.

[@Z-Ack]

Went out and bought a copper grounding rod for 10$ at the home store. Is 8' of solid copper thats 1/2" around.. i sanded it down to just enough to completely fill the space in the transformer then dipped it in floor varnish 3 times along with the rest of the transformer. Cut off the bottom of the transformer though and sanded the varnish on the mating surfaces and a corner on each side. With the winding in its home i hooked one side to negative and othrr side to the positive electrode holder from my stick welder, rubbed a little tinning flux youd use for pipe brazing then with gloves and welding mask on and machine on 200a ac and just gotta make sure that you hit both sides at the same time so i used 2 pieces of wood to guide me and slapped together. No sparks came out and i switched off the machine as soon as i could get to it. Worked perfect.. two halves are together and wont come apart, the winding gives me 120v in and 2v out with enough current to blow my 1500a shunt so 2ka i guess.. dunno. But it makes a hell of a supply for an hho generator and can stay on with a fan indefinitely...

[@BobSmith-qf9tc]

Brilliant tutorial. Thanks so much.

[@electronicsNmore]

Glad you enjoyed it Bob! Be sure to rate thumbs up, subscribe, and look over my video playlists below for many other videos of interest to you. Taking one minute to share a link to my channel with others on social networking sites would be greatly appreciated. Happy holidays! kzbin.infoplaylists

[@electronicsNmore]

I live in flip-flops. I do everything while wearing them, from climbing mountains in Arizona, 20 mile bike trips, to construction work. I am very proficient with them, rarely get injured because of them, and because I never wear shoes, I have no toenail fungus! Well ventilated feet.

[@ronniepirtlejr2606]

When I lived out in the Mojave Desert in California, that's all you wear most of the time.

[@electronicsNmore]

@@ronniepirtlejr2606 I wear them 95% of the time for the past 25 years.

[@Z-Ack]

Good for you.. except wearing open toe shoes doing any kind of construction work.. theres a reason osha has that little rule for construction sites.. you can be careful all you want but shit happens, ie hard hats, safety glasses.. wearing open toe shoes when grinding or anything is like not wearing eye protection, your ok until your not..

[@mechman4]

Outstanding video, thanks

[@electronicsNmore]

Glad you enjoyed it! Be sure to look over my extensive video playlists below for many other videos of interest to you, and most importantly take one minute to share a link to my channel with others. Thanks kzbin.infoplaylists

[@josephuruvathjoseph8285]

Good video ,if I want to make a spot welder how long should be the secondary winding and how thick I don't have thick copper wire so can I take several thin wire and put together to make thick enough

[@enriquecarmona6498]

Hello, I never tried this myself but I think you can use several wires as long as you do not exced two winds. Do a voltage test first though, you should read a little over 2 volts, no more than 2.5. If it works the thicker the better, better inductance and less resistance = hotter.

[@ZaheerKhan-jt6ve]

Hi bro nice informative vedio , can i use the primary as the secondary for 220v and recoil the top winding for the primary and supply 110v through it.

[@nathanthomas7083]

I tried and a spark jumped a gap and put me into cardiac arrest. But I wasn’t far from ER so I’m fine now. Some of the damage was to my muscles. Every muscle in my body contracted causing tiny tears Called micro tears. Causing my sport career to delay. Until now

[@RinkiKumari-bu5my]

@@nathanthomas7083 😆

[@drrrrockzo]

It's easier to multiply the RMS AC voltage by 1.4142 to convert it to peak, which would be the DC voltage across the caps...but don't forget the voltage loss across the rectifier diodes, with a full bridge you are looking at around 1.4V TLDR: VDC=(1.4142 x VAC)-1.4 Assuming sufficiently large filter capacitors.

[@KirkMcLoren]

you can get more turns with magnet wire as the insulation is thinner.

[@nikospalaiologou178]

very good video congratulations.i have one question, what if i use 220 volts on primary?

[@tubeDude48]

Excellent Video!

[@electronicsNmore]

Glad you liked it. Be sure to share the link. Thanks

[@barrygkx]

What a great video. How long of a piece of secondary wire did you use before you started to wind the secondary. I don't want to cut 10 feet and then find out that I am 5 feet short of finishing the secondary wind.

[@electronicsNmore]

20 feet should do it. Be sure to watch my other videos as well. Thanks!

[@matthieuvankints3343]

oke.. this is a really nice project!! went straight to the store and got me an old microwave which was returned for scrapping. they were happy to get rid of it and i was happy to have it :D must say.. i live in europe so my transformer is a 240V version, which i feel shows by thinner wires on the primairy side (compared to 120V) and more windings ending up in a higher resistence (2.5 instead of 0.5). took out the secundairy side and the red wires.. I did just so gently touch the primairy side with the hammer, only some slight deformation there..) resistance is still the same so i believe it will still be fine. it's really just minor. I feel i'll find out when i'll try it out. but i have a something else that bothers me more. At the end of the inner side of the wire there is something connected before it goes to the end pole (so between the beginning and it's pole). i don't know what it is. it WAS insulated (will do again but had to remove it before i could read it. it says ck01 and L145 and i have no idea what it could be. it is easily removed if i need to. fiddling withit i did notice some minor changes in resistence (max up to 9.0) anyone have any idea? would have loved to post pictures here but.. i'll try to add the links from dropbox below. www.dropbox.com/sh/c4xroh6boexpe79/AABtShZB3U6xHPRQ2oBotwFka?dl=0

[@I_am_Rhizomorph]

Nice video.. One question though...if you used the grinder to sharpen the chisel, why not just use it to cut through the windings? or better yet, make a small incision at the weld on the side of the transformer, and separate the "E" portion from the bottom... So you to can slide the windings out whole, and easily rewrap the new wire. Then you can just re attach the bottom of the transformer to the "E" portion, and weld it back together, no problem....assuming you now have a welder.

[@harukoyama9515]

Excellent video... Thank you for the AC to DC calc. While cleaning the transformer I took out all the paper and middle shunt. I remember I saw one you tube video. It say that piece should be removed for more room to turn the primary copper wire. So I hammer it out already. What does that piece of metal in the middle for? Used as spacer?

[@electronicsNmore]

That piece of metal alters the magnetic flux which limits power output. I have many great videos on my channel that cover a wide range of subjects, so be sure to look over my extensive video playlists for other videos of interest to you and most importantly share my channel with many others. Thank you!

[@harukoyama9515]

@@electronicsNmore What will limit flux do to the current? Do I then received less current for my winding? There must be a purpose of this shunt, otherwise manufacture will not have it in the first place. Is for safety? Current noise reduction?

[@NavinBetamax]

No mention about the shunts in the transformer core.........should they be removed or left inside......after you removed the HT coil and the Red wire..???

[@NavinBetamax]

Edit...... noticed that this was answered in the comments 2 years ago.....

[@silviucocolos7958]

I will rewind a Mot next days.I want to make a lead acid battery charger .I have a couple of 100A batterys.I have just one question : does it get hot during function? I was wondering if it s necesary to attach a pc cooler .Thanks

[@electronicsNmore]

+Silviu Cocolos Use the microwave oven cooling fan positioned close to the transformer to keep it cool. :-)

[@silviucocolos7958]

+electronicsNmore Thank you ,i have a couple of capacitor 400uf and 80v each,cand i wire both in parallel ,i want to keep costs to minimum.

[@rickwatkins3085]

Each lamination is insulated from the other, to prevennt Eddy currents, so when you test with Ohms to see if there is a short, you are only testing the laminations that you scratched, another way to test, would get the Ohms resistance rating for the wire on the primary, test that, if it is within range then it is not "grounded", if the Ohms is Higher, then it is shorting.

[@electronicsNmore]

The weld across the laminations keeps them all together, so they can't be insulated.

[@ronniepirtlejr2606]

I used a hacksaw to cut mine off then drilled both sides out with a drill press. Easy as pie if you have a drill press!

[@haz939]

thanks for the well explained answer!! although does the voltage on the primary have an effect on the output? As I have an dual 24v toroidal transformer , once that has been rectified and filtered I get almost 40V DC!! My house has a mains voltage of 251 AC maybe thats why?

[@electronicsNmore]

If you have a 120v to 12V step down transformer, and you supply 150V to the primary, then the 12V output will be higher. If the input voltage is lower, then the 12V will be lower. You have to connect the transformer to the AC power supply, then measure the output voltage under no load. Your 24V is likely putting out around 28VAC. That value rectified is 1.41x the AC voltage.

[@robertfreeman7798]

How many turns and what gauge wire for the battery charger ? Also does the gauge of wire play a factor in the number of turns ? Thanks !

[@electronicsNmore]

+robert freeman Use 12ga wire. Refer to the video showing the lead acid battery charger I made. I forgot how many turns. I have too many videos. Thanks.

[@Symbol84]

I would like to do this for a spot welder. Remove the shunts or not? Do I require thicker gauge wire? 4 gauge or larger? Will the 10 gauge not melt from the current?

[@electronicsNmore]

Hi there, The shunts do limit current, but from my tests, not by that much. MOT's tend to run hot anyway, so I would leave them in. You can always remove them later to see if there is any difference in output. My DC welder works just fine using 10ga wire and 1/16" rods. There is no wire heating problems. If you are looking to make a low voltage very high current spot welder, then use 4ga or larger copper wire(larger is better!). You only need a couple turns on the core using heavy wire. Thanks For watching! Be sure to share and rate Thumbs Up.

[@dancingowljp2939]

For winding the new wire, what length of 10 guage wire would be needed to make 16 - 17 turns for the welding circuit. ? OR approximately how long should the 12 gauge wire be to create the battery charger to reach 13 - 14 volts ?

[@electronicsNmore]

kzbin.info/www/bejne/mpawnomBa5x7hZY

[@petiazza]

Good job. I saw you put an input capacitor to the transformer. Can you tell me how you have calculated the capacity? After you put the capacitor you have measured active and reactive power before the transformer?

[@electronicsNmore]

Use this link here: www.sengpielaudio.com/calculator-RC.htm

[@petiazza]

I saw the link you provided me. But I wanted to know how you measured the active and reactive power before the transformer to the capacitor on and off.

[@haz939]

When calculating AC voltage to DC voltage what does the 0.4 number come from? is that the resistance of the secondary winding?

[@electronicsNmore]

When you convert from AC to DC and add a capacitor to smooth out the ripples, the resulting DC voltage is 1.41x the AC input voltage. The reason why this occurs is simple. When you measure AC voltage, you are getting a voltage reading which is an AVERAGE. If you look at 120VAC on an O-scope, you will see the waveform swings from high to low. If you measure from the middle(zero line) of the sine wave to the very top, that voltage is 170VAC, then it swings down to -170VAC. When you convert to DC, the resulting voltage will be the "peak voltage" of 170V. By adding the capacitor to the dc output, all those ripples from the upper part of the sine wave are flattened out to give you 170VDC. Thanks for subscribing. Please share the videos with others.

[@BenjaminGoose]

Thanks for taking the time to do this video. I gave this a try myself today and it was a little tough (knocking the coil through the core took a fair bit of effort and experimenting with different tools) but with a bit of elbow grease and one severely blunted wood chisel later I managed it. One thing I'm not sure about is that you mention putting the windings one on top of the other, but what are you doing when you reach the top? Do you then progressively wind lower and lower?

[@electronicsNmore]

+BenjaminGoose Hi there. You wind the wire evenly/tightly around the spool back and forth(end to end) until the spool is full. :-)

[@angeldominik650]

i guess Im asking the wrong place but does someone know a trick to get back into an Instagram account? I stupidly lost my password. I would appreciate any help you can give me!

[@abdullahryan8816]

@Angel Dominik instablaster =)

[@angeldominik650]

@Abdullah Ryan thanks so much for your reply. I got to the site thru google and Im waiting for the hacking stuff now. I see it takes a while so I will reply here later when my account password hopefully is recovered.

[@jesusischrist1527]

Somewhere around 15 or 16 turns mine got all mixed up and not very uniform ... The last 2 or 3 were pretty tough getting them through ... I also used 10awg solid so it was extra tricky haha what a finger work out 😆.... I just now got finished rewinding it and have not tried it yet but I was wondering if you have any idea if it will work at all using a solid/single strand ..also I now dont have a working dmm ... 😣😞 haha ...

[@sandydogy]

What has always confused me is the voltage is the number of turns but how do you know how much current you can draw? Say in the UK you have building site 110 volt output, how do they rate what you can draw in current? Thanks Ian

[@electronicsNmore]

Larger diameter primary winding enamel wire, with fewer turns = more current input and output. Smaller diameter primary winding enamel wire with more turns will draw less current and you'll have a lower current output. Please refer to my DIY Custom Transformer video. In the video description area of that video you'll find a transformer calculator. :-)

[@JamesThompson-xl4yu]

If you test the open circuit amps in the primary ( 120 volt input with no secondary connection ) , you will find it draws nearly 1 amp idle current and that means you waste about 100 watt power. The microwave transformer is not designed to be powered constant with the primary winding it has, and needs nearly double the amount of winding for the idle current to be low in the primary. To properly use these cores requires a rewind of the primary coil as well as the secondary. Just a little info for you. Test yours under no load, power on and see what primary current you have. Then feel how hot the cores gets after just a few minutes. Do your calculation (120 volt times the measured current) = roughly the power consumed under no load, that power is making the core heat up.

[@electronicsNmore]

Yes, if you want an efficient transformer, you'd rewind both.

[@TeslaExplorer]

Excellent tutorial! Thank you a bunch!

[@electronicsNmore]

Glad you liked it. I have many interesting videos, and more microwave oven transformer videos as well. Be sure to rate Thumbs Up and share. Thanks.

[@mediaguardian]

I've been harvesting various parts of microwaves and I noticed that some of them don't have standalone transformers but have integrated components on a power converter. The converter feeds directly into the magnetron. Any recommended use for these other than desoldering the components for other uses? Also, is this typical of more modern microwaves?

[@charlesbarnett4240]

I would have used vaseline or mineral oil to lube wire it is a better lube and nonconductive soap is usually conductive. this is a great video.

[@electronicsNmore]

+Charles Barnett Silicone grease and wax based lubricants are the best. The soap works great, and there is no concern about the conductivity of the soap, unless you cut into the thick insulation of the wire. Thanks for watching!

[@cfresque1168]

There is a lot of aluminum clad 10guage cheaper wire on Ebay, are there any complications with using this wire as opposed to the copper? I am trying to make a 12volt to 120 volt inverter. I am having difficulty finding any solid answers by doing a search. Thanks.

[@electronicsNmore]

You need to use one size larger enamel wire in AL to do the same job as the copper, and that means it takes up more space that you may need.

[@cfresque1168]

@@electronicsNmore If I add a couple more mosfets maybe it could be the same effect as a larger primary, perhaps? I think I recall seeing him say that it would increase it, the amps, but there is a language barrier.

[@alberthall6628]

Would it not be safer to use the chisel from the side of the transformer - parallel to the primary - so there is much less risk of damaging the primary by going too far with the chisel?

[@phjr.7889]

I was think the same while watching, almost fully expecting op to do that.

[@haz939]

Very good video you have a new subscriber!!

[@costachegeorgevamavedehote6974]

Hello, why must respect the meaning of the secondary winding in the direction of primary winding, thanks !

[@electronicsNmore]

+costache George vama vede hotel cismigiu If you only intend on using (1) transformer, then not an issue, if you're going to use 2 wired in series, then the direction matters for phase.

[@ionutonea1537]

Hi. Please let me know what thiknes could I on secondary for DIY power supply at 30v DC max 3 A. Thank you.

[@TheDavewhitby]

Great video but you are getting 45 -50 volts,Is it possible to get 240 volts as I live in the UK and our power tools etc run on 240 volts

[@electronicsNmore]

You should still be able to do this. The primary winding for your microwave oven is wound for 220V. The secondary is still the same 2KV winding. Leave the primary alone, and rip out the HV secondary.

[@TheDavewhitby]

electronicsNmore Many Thanks for your reply, Will try this sometime,Would this system work for workshop lighting and general power tools etc

[@electronicsNmore]

Which system? This video only teaches you how to rewind the transformer. You referring to the power inverter? If so, see the modified sine wave power inverter video I have. There are links to schematics in the video description area. Thanks!

[@divasmom65]

New to all of this just like making stuff lol . What other things have transformers in them? Can you use the Primary from another transformer as a secondary? What devices can I find a AC / DC rectifier ? Trying to build a welder I like trying not to buy anything any advice on where to get other parts

[@electronicsNmore]

I got many parts from the dump(electronics/appliances). Many electronic devices have rectifiers. Thanks for watching!

[@divasmom65]

@@electronicsNmore Can you use the Primary taken from another transformer as a secondary? For building a welder

[@MrVetis]

I just plugged mine in an it hummed really loud.. there's no nicks or scratches in the old primary.. Gonna watch some of your other videos to try an see what I am doing wrong. I'm shooting for 7volts for perchlorate electrolysis.

[@electronicsNmore]

Some humming is normal, but not really loud. Maybe your new windings are not tightly wound. Did you check the output to make sure it is 5VAC? Once rectified with a smoothing cap, you will have around 7VDC. Make sure the primary and secondary windings are isolated from the metal core. Place your DMM on a very high ohm range(10-20M) and check from each wire to the iron core. If you get any reading, there is a problem. DO NOT torch the probes with your hands/fingers during the test.

[@lonman4740]

@electronicsNmore, thx for this great video. The only wire i have for winding is those which they use for the wiring of stoves & geysers. The outside + plastic is 4mm with 7 copper strands of 0.8mm each, i'm not sure how to measure the ga. Will this be OK?

[@electronicsNmore]

I would look for some stranded 10ga or 12ga wire. You can get it at any hardware store of old building that is abandoned/trashed.

[@lonman4740]

electronicsNmore Sorry i did not mention that i want to use this T for a 12v batt charger. Thx for reply, i'll see what i can get.

[@ainsworthlynch]

what if I wanted to get 3 wires from the primary (center tap) how would I wrap that?

[@electronicsNmore]

Very easy. Wind 1/2 the turns onto the core, then add a center tap, then continue winding the other 1/2 of the turns. Check out this video as well: DIY Custom Power Transformers Thanks For Watching!

[@liljoey112]

Hello, I am rewiring a mot for 120v to around 28v with a output of around 10 Amps. I was wondering if 20awg magnet wire would be thick enough for the secondary coil.

[@electronicsNmore]

liljoey112 Please refer to my other video below. You can use the transformer calculator software in the video description area of that video. Thanks. Be sure to share and rate Thumbs Up. kzbin.info/www/bejne/aaampnRmaJefj9k

[@matthewbostock6385]

Quick question... Do your primarys get hot when not under load / short circuit conditions? How long can the transformer remain connected before it gets hot? I have tried modifying 2 MOTs now and the primarys get so hot (No shorts between laminations and primarys). Is this just eddy current making the heat? Or is some kind of ballast required??

[@electronicsNmore]

Hey Matt, Usually can get hot if no load is attached, or if excessive current is flowing. Either way. If you are using them for the welder, then there is a "duty cycle" which is low(Around 20%). You cannot continuously weld. You need to allow the transformers to cool for 8 minutes, if you weld for 2 minutes. If you are using the MOT for the 12V battery charger, then it should not get "Hot". Usually it will get warm/very warm. You must realize that the transformers inside of a microwave oven are pushed 50% beyond their intended limits. A 1000w oven , uses a transformer intended for around 600w. The reason why they do this, is to keep the cost down(smaller transformer), and they are able to do that because there is a very high volume fan cooling the transformer while it is running, and the oven is not rated for continuous usage. I would suggest taking the fan out of the oven, and installing it in a housing with your transformers to allow very good cooling. You will no longer have a problem. Thanks !

[@mattjames1978]

electronicsNmore Thanks for that, the transformer is getting hot, smoking hot under no load (Even with just the primary connected). I`m running 230v so for example a quick ohms law calc (800w oven) I=P/V gives you 3.47 amps (assuming maximum load), however 3.47 amps wouldnt get so hot. This is the reason I wondered about a ballast / inductor. I had butchered the laminations slightly so I`m wondering if it is just eddy current making all the heat? Hoppe you can help! Matty

[@thomasferko8666]

How many feet of 12 or 10 gauge wire is needed if I wish to have exactly 12 volts DC later on after full wave rectification?

[@electronicsNmore]

Not too much wire. Refer to my other video, "DIY Custom Power Transformers". I supply a link to download a free program. You enter the required information, and you'll get all info.

[@ahmednaiser4368]

electronicsNmore hi I watch video in you your chanel I won't ask how can make transformer microwave 12 volt high amp for charging car battery thanx

[@johnruscigno5738]

Is the new primary you used, insulated magnet wire or just just ordinary insulated wire?

[@electronicsNmore]

Just insulated stranded copper wire.

[@frame9539]

Hi, I need some help. I have very little electronics knowledge. However, I'm trying to build a power supply for my cordless power mitre saw. I've been told the best way forward is to use/adapt a microwave oven transformer. That's why I'm contacting you because your an expert and if you can help me, I will be grateful. My cordless mitre saw runs off 24v batteries ring from 2.4ah to 3.0ah. The motor requires 630w of power. It's been suggested that I use a 700w use MOT and adapt it, rewire the secondary and so. Ok, that is were my knowledge ends. Can you please advise me the following; 1. What size MOT to use 700w or other 2. What size wire should I use on the secondary 4mm, 6mm and so on 3. How many turns does the secondary need 4. Do I need to use a bridge capacitor 5. Do I need any other electrical wiring Please help as I really want to get this project off the ground. Kind regards

[@electronicsNmore]

Frame Please refer to my other video below. There is a link to a program which you can use to figure out what your need. Thanks. Be sure to rate Thumbs Up and Share. kzbin.info/www/bejne/aaampnRmaJefj9k

[@kevinanderson9243]

I followed your instructions and after I made a rectifier from 4 diodes I tested my output and was very happy to get 15.4 vdc . I soldered clamps on each lead and found an old battery which measured 4.4 vdc so I hooked it up. After 1 hour I checked it and it was at 10.2 vdc but what alarmed me was the transformer! It was too hot to touch! It buzzed VERY loudly...normal...but was so hot I couldn't possibly hold it without gloves on my hands. I immediately unplugged it to let it cool down. Any advice?

[@electronicsNmore]

Hello Kevin. A lead acid battery with 4.4V is trash. The voltage will never rise to a fully charged state. ONLY use this to charge a good battery which was allowed to drain down, not a battery that was sitting for a very long time at a very low voltage which is full of sulfation. The buzzing is caused by the windings vibrating. If they were very tightly wound, you wouldn't hardly hear a thing. As for the heating issue, these transformers were not designed for this purpose. If you don't replace the primary winding to make it run cool, then it needs to be cooled using the fan from the microwave oven, Place the transformer in a housing, cut a hole in one side to allow air to be drawn in and around the core, then place the fan on the opposite side of the housing blowing the air outward. The heating issue will be gone.

[@martyspencer7182]

Thanks for the video !.... has anyone used a rewound MOT, heat sink, capacitor & rectifier to build a 120 volt AC to 20 volt DC power supply for a DeWalt battery powered miter saw (or other power tool) ?

[@Cdbarron727]

Is it really trash if the primary gets scratched? I saw a vid claiming to be able to fix the primary

[@electronicsNmore]

It depends. If it's a minor scratch, you can apply some clear nail polish over the area. You need to make sure the windings aren't shorted out in the scratched area. Thanks for watching!

[@JUANKERR2000]

Why worry about the winding direction? Unless you are intending to interconnect primary and secondary the winding direction are immaterial.

[@electronicsNmore]

Exactly. That's why I suggested putting things back the way you found them. I use (2) of these in series for my DC welder. Phase matters.

[@JUANKERR2000]

electronicsNmore - thanks for clarifying that :-))

[@nomanwadood3117]

dear sir when i was removing secondary winding of mot i damaged the primary could you please tell me how many turns and layers requred on primary winding,?

[@eljarrito8181]

Try taking a car battery ground strap for a single turn secondary. That makes a DIY SPOT WELDER. (You will need a Variac on the primary side to adjust the power.)

[@electronicsNmore]

kzbin.info/www/bejne/eILMnKyOgsp2bdk

[@brickwal92tt]

I have little understanding of the science behind all this but I have a question and I hope you can educate me with an understandable answer. Would it be possible to take 2 of these transformers and combine the primary coils of both into one rather than winding your own secondary? I somewhat understand that the more windings result in more voltage? So by winding a new secondary with thick wire, I'm drastically dropping the voltage? So will using a primary from another transformer be too many windings, thereby resulting in too much voltage? I've seen plenty of these types of videos but I wish more would take the time to explain the science behind it all for those of us ignorant but wanting to learn.... I want to create a welder to repair my trailer and small other jobs. From reading reviews on Harbor Freights $100 welder, I'd be waisting my money. Also, would using more than 2 of these transformers wound like your way, show any benefit, such as 3 or 4?

[@electronicsNmore]

+brickwal92tt Hi there. The transformer output is based on the ratio of turns between the primary and secondary. If you use the same winding for the primary and secondary, then all you end up with is the same voltage output. Basically an isolation transformer.

[@enriquecarmona6498]

Hi, to answer your question about using more than one transformer, the answer is yes you could. Adding another transformer in parallel will increase your amperage output allowing to melt thicker plates. I've seen guys using up to four transformers in parallel. Understand the primary windings are connected in parallel but the output is connected in series. Taking care of using same wattage transformers, do not mix 'n match.

[@19134ANDY]

how many volts should the two secondary wires put out. not the one that goes to 12 volts. can you please help on the inverter..

[@electronicsNmore]

+Andy The Truth VAC output will vary. You can adjust the output by adding or removing turns from the low voltage side of the transformer.

[@electronicsNmore]

+Andy The Truth VAC output will vary. You can adjust the output by adding or removing turns from the low voltage side of the transformer.

[@batticha462]

May be I missing something here, What's the important of winding direction ? and what happen if it made in the wrong one ?

[@electronicsNmore]

It's habit for me to put everything back as I found it to avoid problems. If only making one, it makes no difference, but if you plan on using 2 in series, the direction of turns must be correct. Thanks for watching!

[@batticha462]

electronicsNmore THANKS

[@astrataway7077]

Question. Theoretically speaking is it possible to wrap 6 gauge or whatever gauged wire ''loseley'' with slack or loops for adding taps? The sectional density would still be there in the core but all windings would be given a certain amount slack outside the core. Would it still work? I want to build a welder I got about 10 suitable MOTs but It's gotta be adjustable. I want to add a contractor switching wheel

[@dive2663225]

Be interesting to see what happens to Hz when a pot isadded with the cap bank? thanks again very interesting good presentation

[@electronicsNmore]

You'll like my other, older video. kzbin.info/www/bejne/qqrZi3p_oa14pc0

[@santoshmane3383]

It is very informative, thanks a lot. I congratulate you and thanks alot

[@electronicsNmore]

You are welcome!

[@vsolon7]

Doing this I may have scratched the primary a tiny bit, you can see some of the copper, so how much will it affect it or is it no good? If it's no good can you rewind the primary coil?

[@electronicsNmore]

Not a big deal. If you only scratched the outside, and the adjacent wires are not shorting where you removed the enamel, then your fine. Take some clear nail polish and apply it to the scratched enamel wire. If they are shorting, gently separate the wires then apply the nail polish. Thank You. Be sure to check out my video playlists.

[@gatorwing6231]

Insert a short piece of 1/16" piano wire (about 4" each) being at the top and at each end on one side of the primary (tap in lightly with hammer). Cut close to the iron core with a fine tooth hacksaw. The piano wire is too hard for the hacksaw blade to cut so it stops the blade preventing the primary from damaged. I just cut the secondaries off two transformers. Ten minutes each and no damage to primaries.

[@anthonyalleyne634]

I would like to use this application to solder jewelery together with solder wire , my question is how many turns would be needed to do this as I'm guessing that to solder I will not need the electrodes to be as hot as for welding.....can any onehelp or am I out to lunch on this one? Thanks much

[@TheFootbaldd]

+Anthony Alleyne think about using a much smaller transformer that has a standard secondary and for control you could setup a triac with a pot to control the duty cycle. You could also use pid control if you want the equivalent of a soldering station. Or just get a 30-40 watt non regulated soldering iron for 25 bux.

[@barthchris1]

+Anthony Alleyne NO! Depending on how many winds you rewind, you can easily melt a 6 inch 1/4"x20 threaded rod in seconds by rewinding the secondary. Way too much-unregulated current even with a lot of winds.

[@pikaonyoutube2139]

how much current would 4mm squared wire give out if i rewound a mot with it its household wire with 7 thick strands of single wire that make up the wire itself the mot has 6170w marked on it i believe its the rating of the transformer

[@electronicsNmore]

hansley maharaj I have no idea. That number does not sound like the rating. You need to do a Google search for that part#, and use the software shown in the video description area of my DIY power transformer video. Thanks!

[@Tarkebatcom]

I want to make it as a battery charger. How many rounds and which kind of wires I should use. Another question pls, How many amp I can obtain?

[@electronicsNmore]

Hi Zakaria. Have you watched my other video showing a simple 12V battery charger I made using a microwave oven transformer(MOT)? I am pretty sure I mentioned how many turns I used in that video. 12ga wire is fine, and keep winding turns onto the transformer until you get measure a 14-15VAC output. Once you use a full wave bridge rectifier at the output, with a large value electrolytic capacitor(No need to smooth out all the ripples, ripples are fine for a lead acid battery charging) you will have approximately a 20VDC output at 10 Amps. Be sure to use the cooling fan from the microwave oven to keep the transformer cool! Thanks For Watching! Be sure to share my channel with others and rate Thumbs Up.

[@1pcfred]

OK this has been bugging me, so I'll ask. How come you chop down in the direction of the primary winding? Why can't you put the transformer on its side then chop to the middle, where there is nothing that you need to worry about damaging? Basically 90 degrees to what I see going on here. I am really interested in the rationale for why that would not work. Because it is just not coming to me.

[@electronicsNmore]

+Paul Frederick Never been mentioned before, but you can do it that way also. You do it the way you feel most comfortable. You still have to be very careful because the primary winding is very close. The reason why I chose to do it the way I did, is because the steel plate on the bottom of the transformer makes the job much more stable because the plate extends beyond the cutting area. Remember, there is almost always a reason for everything I do. Thanks For Watching

[@1pcfred]

electronicsNmore Yeah right before you flashed up the message about holding the transformer in a vise I thought the same thing myself. You must be very flexible to work on the ground like you do. Those days are over for me here. I like to work like a gentleman today. I'd probably use this www.instructables.com/id/Make-a-Tripod-Vise-Stand/ because it is a perfect height for gaining an advantage over something for me. That is no accident either. I made it that way.

[@allenmckinney9533]

+electronicsNmore Some transformers are turned 90 deg already. I have 2 transformers that are setup the same except one has the plate on the side so it would be easier to cut it from the side like Paul said. I'll more likely be using a clamp and my porch hand rail to hold it anyway my self.

[@TheFootbaldd]

+Paul Frederick I just use a hack saw to cut, using a chisel sounds like a good way to screw up. I guess that is a bit quicker though.

[@electronicsNmore]

Hello there. Using a sharp chisel is the easiest way. When you get close to the bottom of the winding, then you can use a 32tpi hacksaw blade to finish off if you do not trust yourself with the chisel.

[@highlanderoutsider5259]

Enjoy your shows though thanks

[@jaggid87]

Hi mate, can you tell the secondary thick wiring is clockwise or anti clockwise

[@tesladude2822]

Exactly! It does not matter how you made your secondary clockwise or not

[@electronicsNmore]

If you're only using one MOT for a project, then you're right, but when connecting 2 transformers together in series(Like in my microwave oven stick welder video) or parallel, the direction(phase) matters.

[@pulesjet]

I used a Hack Saw to remove the winding . Just cut one side and punch the rest out with a long bolt. Like 5 minutes tops and a pile safer on those winding's. If I had a welder I would just cut the welds and take it apart.

[@electronicsNmore]

Whatever works! Be sure to check out my extensive video playlists for other great videos of interest to you, rate thumbs up, and share my channel with others. Thank you

[@mrundead6438]

What are thoseee!! 👍👍 Good video

[@electronicsNmore]

Glad you enjoyed the video! Be sure to rate thumbs up, share, and subscribe. Thanks

[@mrundead6438]

I have subscribed 😁

[@nielsdaemen]

What's the no load core losses of this thing?

[@eddytan4479]

hi, is there any different if i accidently swap in ""LIVE"" voltage into ""NEUTRAL"" for primary with this kind of project? will it cause explosion???

[@wh459]

Could I get 6.3v at 100a out of a 240v mot do you reckon? How thick would the wire need to be?

[@electronicsNmore]

You need to rewind the 220v primary using just under 500T of 25/26ga enamel wire, and 2T of 2/3ga insulated stranded wire for an output of 70 Amps at 6.3VAC.(According to the transformer calculator I used). This is based on a core cross-section of 31 x 70mm. 100A is not going to happen unless the core is larger.

[@wh459]

Cool! Lucky I got two 1200va 32v transformers which are huge! Also explains why 20a at 12v is heating up my rewound mot. What is this software you mention?

[@wh459]

Thanks for the info btw. I might have learnt the hard way.

[@electronicsNmore]

Refer to this video also: DIY Custom Power Transformers

[@enriquesalgadoaceves9017]

OK so I got a micro hydro turbine puts out between 60 and 80 volts only problem is it puts out like 30 amps, how can I tie it to a mot or anything to get more amps?

[@electronicsNmore]

You can't get more amps.

[@uoit01]

Excellent tutorial! Out of curiosity does anyone know what the inductance of a primary winding on a typical MOT is? I am making a Choke-input filter to remove the ripple voltage from a 110V 4A dc power supply and looking to find or make a 3 Henry inductor. Is it viable to rewind a MOT with 18gauge wire to make an inductor of that size?

[@electronicsNmore]

The primary winding usually measures between 17 and 38mH.

[@uoit01]

electronicsNmore Thanks for the reply guess i will have to remove both coils and see if I can get enough 18 gauge wire wound on to the core to get 3H. If any one has experience making inductors this large any comments are welcome. Thanks.

[@fireinthesky4982]

Even if you scuff up the primaries, not all hope is lost. You could probably just run nail polish on the bare spots and they would be fine.

[@electronicsNmore]

+Fire In The Sky True. I used clear acrylic nail polish many times in the past.

[@benlawton5420]

When I was knocking my secondary out the bolt put a pretty big scratch on 2 wires so I pulled them away from each other an then put silicon in between them and it hasn't blown up XD

[@fidonol]

thanks you saved me

[@xyed1986]

Hello sir I love your videos, my transformer gives me 24v ac but when I connect bridge rectifier then it drops to 19v dc I think that the bridge rectifier is eating up the voltage please guide me

[@electronicsNmore]

That makes no sense. You're doing something wrong or have a faulty bridge rectifier.

[@xyed1986]

its 50v 50 amp bridge rectifier

[@xyed1986]

i think its faulty

[@xyed1986]

ok thank you sir

[@woodyphyseter3671]

How important is the protective paper/film?

[@electronicsNmore]

Just don't damage the enamel coating on the windings. Thanks for watching!

[@woodyphyseter3671]

@@electronicsNmore Thanks, also does the transformer get hot at all? how important is it to keep it ventilated? (wooden box)

[@CirkaTusen]

You should get a proper insulation tester to test the insulation of the windings at higher voltage (500V/1kV).

[@electronicsNmore]

I have one, as well as a video on my channel. :-) This video was made for the AVERAGE person, not people with Meggers.

[@JTWLJK]

I have a mot from a 1000W Kenmore Elite. Rewound secondary to a rectified 14vdc. With small load 55w or no load the primary draws 7.5 amps continuous. Is this normal. I was going to try to make 10amp power supply.

[@electronicsNmore]

The transformer is saturated. You'd need to rewind the primary with more turns of thinner wire. :-) Refer to my "DIY power transformer" video, there's a link to a winding calculator.

[@rachidziadi5050]

Great job with patience

[@electronicsNmore]

Thanks! Be sure to rate thumbs up and share my channel with others.

[@faridnaser4315]

Thank you

[@samnile2]

Please, could you give us the transformer formula for winding the secondary We use 220volts

[@electronicsNmore]

My other video has a program that you can use. kzbin.info/www/bejne/aaampnRmaJefj9k

[@Debraj1978]

I like the improvisation, also called "jugad" in India.

[@electronicsNmore]

Thanks for watching! Be sure to rate thumbs up, check out my extensive video playlists for other great videos of interest to you, and share.

[@KAFKUBA]

Nice but why waste the magnet wire from the secondary?

[@electronicsNmore]

It's not too useful, and usually made out of copper colored aluminum.

[@KAFKUBA]

@@electronicsNmore I think it's copper...thin but copper

[@peterzingler6221]

Is there a Problem with winding one for 240 to 30v ? Like saturation or something?

[@electronicsNmore]

No, you need to refer to my other video "DIY Power Transformers". Thanks for watching!

[@KAFKUBA]

Very practical and smart guy...thank you

[@electronicsNmore]

You're welcome! Be sure to look over my extensive video playlists for other great videos of interest to you and most importantly share. Thank you

[@kalleklp7291]

Why does it matter which way the coils go? I mean it's AC, so the current will shift polarity 100 times each second..50Hz.

[@electronicsNmore]

If you're going to use (2) transformers in series or parallel, then you need to make sure the phase is correct. If you're only using one, then no big deal. I do it out of habit because it makes things easier.

[@kalleklp7291]

electronicsNmore Ahhh...now I understand why. If you use two transformers in series and the phase ain't correct, they would cancel each other out. Thank's for explaining that. I'm not a pro on electric things, as my profession is blacksmithing and machining. I want to make a compact spot welder for my workshop, hence the interest for such transformers.

[@electronicsNmore]

Kalle Klæp If you only wind one transformer, it won't make any difference which direction you wind the transformer, especially if the output is converted to DC. :-)

[@kalleklp7291]

electronicsNmore Thanks a lot for your help, I appriciate it..