“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.
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.
Write if more information is wanted.
-Howard
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