On 2008-04-29, Jon Danniken wrote:
"Ignoramus18948" wrote:
Another point is, SCR driver boards are expensive. I was very lucky in
that for some readon, PCTI liked my kids site algebra.com so much that
they donated a SCR driver device to me, which was easy to use.

Still, I would be far better off applying my efforts elsewhere,
wotking less hours, and buying a great new welder. That said, I
learned something.

Those are some good points you make there. I guess what I am trying to do
is use a handfull of discrete componenets to make as simple of a
variable-current supply as I can get away with. Perhaps the only way to
control the current is with a highly-advanced topology, utilizing complex
circuit boards, but if there is a way to do it with a minimum of components,
then I am going to try to do this.

I guess what I really need is to look at a schematic of a transformer-based
TIG supply that used SCRs to control the output current, and see how they
did it there, but I don't know the name of any units that used such a
control method, much less have a schematic.


Look at the manual of Miller Syncrowave 250. I believe that it
includes an intelligible schematic and uses SCRs.

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