Transformer Help

[inmate]

Homemade Welder Help plz

i am atempting to build a home made welder from microwave transformers and was wondering 1 if there are markings on the transformers that would tell me how many windings there are in the primary and secondary. second if the secondary could be re wound using stranded wire instead of single conductor wire. and could i make my own transformer using a solid steel core like a u bold or steel ring instead of the lamanated trasformers in a microwave with acceptable results and how many windings would i need ie 100 on the primary to 20 on the secondary.

http://www.dansworkshop.com/Homebuilt arc welder.shtml
http://www.geocities.com/aaawelder/

 

[Hero999]

could i make my own transformer using a solid steel core like a u bold or steel ring instead of the lamanated trasformers in a microwave with acceptable results

No you couldn't, the eddy core loss would be unacceptable, it needs to be a laminated core.

Another thing is for safety's sake you need to ensure the secondary is properly isolated from the primary.

Also be aware that AC is more dangerous than DC, 40VAC is about as dangerous as 90VDC.

 

[rezer]

No you couldn't, the eddy core loss would be unacceptable, it needs to be a laminated core.

Another thing is for safety's sake you need to ensure the secondary is properly isolated from the primary.

Also be aware that AC is more dangerous than DC, 40VAC is about as dangerous as 90VDC.

Hero999,

Is AC more dangerous than DC? At what frequency does it become less dangerous at the equivalent DC current? Is it more dangerous at low frequencies (i.e. line freq.)? It was my understanding of current flow, that DC is more dangerous do to the non-alternating nature of the current. I do think frequency plays a major part in this. There are many sites that discuss the issue, but non agree.

 

[inmate]

but could i use stranded wire???

 

[rezer]

but could i use stranded wire???

No, you want to use solid wire if your wiring a transformer.
I want to clarify my questions on my earlier post:
It doesn't make any difference which is more dangerous, AC or DC, BE CAREFUL!

 

[mneary]

Why do you want to use stranded wire? It won't appreciably reduce skin effect, if that's what you're driving at.

 

[rjvh]

Hi inmate ever looked to a comercial welder and the size of its transformer???

its a pretty bigg one that your microwave transformer can't match

You can use stranded wire for a transfomer (the wire must have a form of insulation) but it will not be efficient to use as stranded wire uses more space (square mm) for the same wire surface as a solid one

Robert-Jan

 

[Hero999]

Hero999,

Is AC more dangerous than DC? At what frequency does it become less dangerous at the equivalent DC current? Is it more dangerous at low frequencies (i.e. line freq.)? It was my understanding of current flow, that DC is more dangerous do to the non-alternating nature of the current. I do think frequency plays a major part in this. There are many sites that discuss the issue, but non agree.

Yes, frequency does play a large part in it.

Low frequency AC (50/60Hz) is more dangerous than DC because it's more likely to cause ventricular fibrillation.

High frequency AC (+20kHz) is less dangerous than DC because the nerves don't respond to it.

How AC affects the body depends largely on frequency. Low-frequency (50- to 60-Hz) AC is used in US (60 Hz) and European (50 Hz) households; it can be more dangerous than high-frequency AC and is 3 to 5 times more dangerous than DC of the same voltage and amperage. Low-frequency AC produces extended muscle contraction (tetany), which may freeze the hand to the current's source, prolonging exposure. DC is most likely to cause a single convulsive contraction, which often forces the victim away from the current's source.

AC's alternating nature has a greater tendency to throw the heart's pacemaker neurons into a condition of fibrillation, whereas DC tends to just make the heart stand still. Once the shock current is halted, a "frozen" heart has a better chance of regaining a normal beat pattern than a fibrillating heart. This is why "defibrillating" equipment used by emergency medics works: the jolt of current supplied by the defibrillator unit is DC, which halts fibrillation and gives the heart a chance to recover.