[Shop-talk] Yet another TIG Welder question

[David Scheidt]

On Fri, Jan 7, 2011 at 9:04 PM, Douglas Braun <doug at dougbraun.com> wrote:
> There seem to be some Chinese AC-DC welders starting at about $1000, but
> that's not much less than the price of a Miller Diversion 165.
>
> I don't understand why AC-DC welders are so much more expensive (and
heavier)
> than Dc-only machines. B I was looking at the Diversion schematic, and the
> AC capability is supplied by an electronic inverter switch between
> the Dc power supply and the gun. B The inverter is basically 4 big
transistors
> that alternately connect the positive and negative output to the gun
> and work connections.

Those are four big, high-power IGBTs.  Last time I looked, they cost
about 200 bucks a pop.  That's low volume pricing; nobody making
welders is paying anything like that, but it's still a big chunck of
the price.

--
David Scheidt
dmscheidt at gmail.com