i am certain the pulse is pulsing up, not down. did you watch Jody's video in the link i posted?I thought the pin out would be helpful. With it a second pedal could be made with the pulse built into it. Still think it could be done with two pots, voltage dividers. The high one set by the pedal position, the low one manually.
Quote,^ "a pulse is a pulse of higher current." Think that is backward. The pulse is the low current. The high current is the welding current, it pulses to a lower current to control the heat.
I never liked the pulse myself. A lot of guy's use it as a crutch, instead of learning how to weld correctly. As a way to try and get the "stack of dimes" weld bead.
if i were to adjust duty-cycle to more than 50%, then the pulse at the tip of tungsten would seem like it was pulsing down.