this post was submitted on 18 Oct 2023
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Hi, I have built a microvawe transformer spotwelder, I have put a single turn of welder wire for in the secondary and I'm timing it with arduino. Worth mentioning it was/is a 230V transformer. Electrodes are sharpened copper rods. I believe the voltage is still high. The spotwelds it produces are slightly discolored and not as strong as you would expect. Is this design fundamentally borked? Is there anything else I can make to make it better? Photo from test stage before it was built into a project box, it is less "shocking" now.

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[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

If it's a 240v transformer, the primary will have less turns than a 120v one. You may not have a high enough voltage out of your new secondary because of that.

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

Would trimming down the voltage on the primary with a triac would help?

[–] [email protected] 2 points 1 year ago (1 children)

You need to go up in voltage, not down.

Try it on 240v. (check your 5v supply can handle that, or power it separately)

[–] [email protected] 1 points 1 year ago (2 children)

I have 230V or 400V three phase. I live in the EU. So this cannot be solved without replacing the winding on the transformer I guess.

[–] [email protected] 1 points 1 year ago

If you have a 230V supply and a 230V transformer, you are fine. I believe they thought you were using a 120V supply on a 230V transformer.

Raising the input voltage will probably not get you what you want.

[–] [email protected] 1 points 1 year ago (1 children)

If it's just a matter of getting a larger voltage, then you already got 400V. No need for new windings, unless the insulation on the primary can't handle 400V.

[–] [email protected] 1 points 1 year ago

I need lower voltage. 1-2V on the secondary. I have 3V rms now.