home-made pedal pulser for old PowerTig 200DX?

Hello Everlast Equipment,
I have an old 2011 PowerTig 200DX. On this basic machine you can pulse in 4t (.5-25 Hz) with the torch trigger, but not in any useful way with the foot pedal in 2t (except for whomping on the pedal). So I am thinking of making an Arduino-based pulser tied in to the pedal (the one with the rheostat knob) and I need a pinout diagram or schematic showing voltages / functions of the cable connect pins. As my electronics are rudimentary, my understanding by looking at the pedal internals is that the pedal input voltage (5v, 2.7v?) comes in on pin 5 (red wire inside pedal) and that the modulated voltage (controlled by rheostat and pedal potentiometer positions) is read by the welder on pin 4 (yellow wire) and green wire is to pin 3, a ground or 0v. Is this correct?
PS: the associated Arduino programming and potentiometer controls are pretty straight forward.
Thank you, your help is appreciated.
-Howard

“I like my welders like I like my women: with a pulse” (This old Tony)

Did it! -- pulser for the old 200DX pedal. (Now I know this is only of interest to the 5 people who have these old welders, and thanks to Everlast for a pinout diagram which confirmed my understanding of pedal internals.) The idea of a pedal pulser is to control the overall heat of the pulse while welding.

In design of this pedal pulser, all one does is intercept the pedal output voltage and pulse it. This is described at https://www.youtube.com/watch?v=hk02102nefk (see image #1). The Arduino chip does the pulsing and its program takes its values for frequency and time-on (aka “duty cycle”) from 2 potentiometers. A third potentiometer is used to set the background current as a percentage of the pedal signal. Image #2 shows the combined output voltage signal as the pedal is pressed down and let up. Image #3 shows the breadboard setup wired into the pedal, image #4 shows a more robust setup about to be attached to the welder.

Attachment 13839
Attachment 13840
Attachment 13841
Attachment 13842

And it works. I’ve not had a lot of time on with this setup, but pulsing does indeed respond to the new knobs and how far down the pedal is mashed. When compared to the built-in torch-trigger pulser, the floored pedal pulses seem a little cooler. I’m looking into this now.

With the ability to essentially custom-program one of these old 200DXs via the foot pedal interface, all kinds of interesting possibilities open up. How about a blast of 3 one second full-power pulses one second apart then nothing for 10 seconds, then repeat? (or whatever). Maybe great for tacking or spot welding. Lots of possibilities. An Arduino Duo chip can output voltages at any desired level (< 5v). Seems like somewhere a bit north of 3.5 volts will tell the 200DX to blast out 200 amps (image #5, amperages read from the welder’s control panel). A number of pedal mods suggest themselves too.

Attachment 13843

Write if more information is wanted.
-Howard