How to make a Cheap transformer for a project?

i need to make a cheap step downtransformer for making a small arc furnace....i saw the project on youtube and the link is given below
https://www.youtube.com/watch?v=JIlZsuRc9jQ...i used carbon rods from AA 1.5V cells and i need a transformer that can be made from home available items like wires from dc motors and tube light chokers ...please give me details about materials required and the method of constructing

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The author of the video you link to, King of Random (KOR), is also a member of Instructables, and he wrote a whole bunch of notes and pictures for this project, here:


and here:


I am guessing that used microwave oven transformers (MOTs) are probably the cheapest way to get the laminated steel core, and the primary windings, from used equipment. Well, that depends on what the junk market looks like where you live. If you get lucky, you might find an old microwave oven in a dumpster, or even an old welder transformer, if really lucky. But sort of a more reliable source than dumpsters are the thrift stores,


because that's where people take their old, almost-broken junk. Or at least this is the way it is done in my home country. Then the thrift store, collects the junk, and resells it to you, but usually at very low prices, circa 10% what it would cost new.

Note the secondary winding for KOR's welder transformer was very thick wire. He used 8 AWG, insulated, stranded copper for that. Also, I'm pretty sure the resulting transformer is step-down. That is, its output voltage is lower than the mains voltage, but with higher current at the output side.

If want to know more general information about how transformers are put together, I think the Wikipedia article might be a good place to start,


iceng2 years ago

You get cheep by going free. No offense but if you could, you wouldn't ask in these terms. I hope you find the videos informative. You realize you are dealing with death within the time of twenty heart beats if you make one of 6 mistakes.

That shouldn't scare you as a little pain and then oblivion, BUT there are more instances where you get to be a Hawkins minus the brain power for more time then you can imagine where you mess yourself and can't do nuttin for it !

ShwetangP (author)  iceng2 years ago

i wasn't able to even understand a single you said but still thank you for that advice..

iceng ShwetangP2 years ago

Im trying to save pain for those that love you.

An electrical current (shock) across your heart (chest) does not stop it but throws it out of sync such that both chambers contract at the same time instead of sequentially. The end result of this fibrillation is blood does not

carry oxygen thorough your body even though you are trying to breath. This will be very painful for a short time then you will become dead (oblivion !)...

You probably believe only high voltage is dangerous BUT there is a record in text of a man dying of 6VDC in the 1920s.

The videos are explicitly informative but assume you have safety knowledge in your workarounds which can expose you to the deadly consquences.

-max-2 years ago

Those are step DOWN transformers he showed in the video. Notice that the carbon rods had to touch before an arc was drawn? and how hot the arc was? That means high current, low voltage. Also, if you look at his modified MOT's, you will see the HV primary has been replaced with only a few turns of really thick wire.

what he had show WAS the cheapest way to do it, at least to get the performance that he showed in the video.


To make a high current transformer that operates directly off of mains, you need a laminated transformer core, lots of wire, preferably copper magnet wire for the primary, lots of turns for that, and some really thick insulated wires for the secondary. Then you build it up.

If you have to buy the parts, you cannot do it for much cheaper than $30. And you would waste so much time in the calculations for the number of turns so that you do not keep blowing fuses and circuit breakers, and get respectable current and power output, and of course winding the primary coil. It is far easier to modify high power transformers, which already have the primary you need with the correct number of turns for the magnetic core used. Obviusly you can use some MOTS, and some other large transformers. the typical MOT is like 1000VA, or something like that, look around for a transformer with the same rating.

ShwetangP (author)  -max-2 years ago

Yeah i realised it was a step down transformer and then i changed my question....i also found a simple transformer from wikihow tutorials so that solved my problem

rickharris2 years ago

If your looking for cheap then you need to source second hand wire. Perhaps by breaking down an old transformer.

Wire, Core and insulation are never going to be cheap unless bought used.

The guy outlines how to make the transformer in a separate video and he even gives you an on screen link to said video. There is your full instructions for making it from home available items. I'm sure you don't want to tear apart your microwave but you can get a couple of microwaves from your local good will store for cheap.

On a side note, if you don't have much experience in such things it would probably be best if you do not attempt such a project. As it is extremely dangerous to build much less use.