I've been putzing with a design for an add-on pulser for my Miller 180SD TIG welder at work. After 3 years, on-and-off (mostly off), I've finally got a working unit. I posted it under "TIG Pulser" on the Dropbox:
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I finished it today, so I can't give you any long term use information. But, it seems to work as designed.
Many thanks to Gary Campbell, Ray Sommer,....and especially Ernie Leimkuhler for his willingness to share all his welding experience with us.
Ken