On 2008-04-29, Jon Danniken wrote:
"Ignoramus18948" wrote:
Jon Danniken wrote:
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.

Aye, thanks Iggy, that is a readable schem. It looks like they are using
the SCRs in place of the bridge for controlling the current, but are using
an IC (or another unspecified group of components) to drive the gates.

Yes, that's why you need an SCR controller to go with the SCRs.

I wonder if there were any TIG supplies that used a more simple
method of controlling the current, maybe in the pre-IC days?

Don mentioned another method. I do not recall what it is.

This is a project that I am kind of happy that it worked, but I regret
starting it, the time wasted, etc.

--
Due to extreme spam originating from Google Groups, and their inattention
to spammers, I and many others block all articles originating
from Google Groups. If you want your postings to be seen by
more readers you will need to find a different means of
posting on Usenet.
http://improve-usenet.org/