On 2/13/2015 11:58 PM, Phil Allison wrote:
mike wrote:


Problems I discovered with these welders a
600W ain't nearly enough power to weld anything substantial.

Very thin stuff like battery tabs require very accurate energy
delivery. The difference between no weld and blasting a hole
thru everything is a small pressure difference holding the weldment
together.

If you don't turn it on/off at zero crossings, the saturation
state of the core can make a great difference in the next weld.


** Zero crossing switching is the worst possible for creating large in-rush surges and hence fully magnetising the core of an AC supply transformer.

Switching on at a voltage peak, while under load, is the best option.

A triac switch will always go off near zero current, which will be nowhere near zero volts.

... Phil

Well, I don't recall mentioning volts at all.
Yes, triacs switch off at the zero crossing of the current.
Not much you can do about that.

I question not turning it on at zero volts???
Please explain the large in-rush current when there's zero volts
on the transformer primary?