Might be an idea: Push button amperage control

[welderdude]

if you really wanted to, you could rig up some kind of geared motor to adjust the pot in the foot pedal. the switch would just have to turn a motor on and off in either direction.

[zoama]

I was actually thinking of using an op-amp integrator circuit for the applied DCV - small package and cheap...

How soon can you test ?

[welderdude]

Ken, I definitely agree that would be the best way to go about it. I was just thinking outside the box in a simple way. On another note, I wonder if using a pressure sensitive switch would be practical so the harder you push, the faster the amperage will increase or decrease.

[Zmechanic]

I was actually thinking of using an op-amp integrator circuit for the applied DCV - small package and cheap...

That's a pretty good idea (the up and down buttons for ramping). I never cared for the idea of having to twist a pot on the torch.

If you do that, I'd suggest the OP97 from analog devices. It has very good bias current performance, especially over temperature. It's actually a bipolar device that's compensated, rather than FET input, so it doesn't have the nasty doubling every 10 degree behavior. They aren't that expensive either. I've used them for sample and hold circuits, which is essentially what you'd have, an integrating sample and hold.

Throw down some JFETs to switch the +/- charge pumps, and you'll be set!

[welderdude]

I was thinking something like the pressure sensitive buttons that the play station 2 controller used.(the square,triangle, ect buttons) It would still use a up and down button, but the rate at which the curring setting would increase or decrease would depend on how hard you pressed the button. If you pressed down hard, the current would increase/decrease quickly while if you lightly squeezed it, it would slowly go up/down.