I've got a simple tig welder that uses a switch on the torch to start the welding current and a potentiometer on the front panel to set the amperage. Many welders make use of a foot pedal to start te welding current and also control the amperage level with your foot for a bit more control of the welding action. This welder doesn't officially have a way of connecting a foot pedal but I think it must be possible and tried adding one.

Tig welder

I bought a foot pedal that has a two pin connector and a three pin connector. The two pin connecter wil connect to my tig welder as is and it will trigger the welder to start just like the button from my torch would. I've now got foot control but can't manipulate the amperage.

Inside the welder the pot meter is hooked up to the connecter circled red. The outer lobes trace to a bunch of resistors and the centre lobe traces to two pins soldered together on the unused connector circled yellow. Maybe that connecter is there for adding a foot pedal. I can't seem to find any info on this welder anywhere.

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Back to the pedal. The three pin connector is coming from two potentiometers in the pedal. Wired as follows.

enter image description here

I could match the potentiometer value of the pedal to the one in the panel but I would also like to be able to set the max current on the front of the panel and use the foot pedal to control the amperage within that range.

I've got it sort of working now by swapping the b103 10k potentiometer on the back of the pedal and hooking up the 1k potentiometer from the panel like can be seen here.

enter image description here

It is however not working as it should. I can only see and set the max amperage when the pedal is fully pressed. Also it won't go as low as it used to due to incorrect potentiometer value. I am sure there is a better (correct) way of doing it. Any help would be much appreciated!

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    \$\begingroup\$ I don't know if I would wire anything differently. The thing to check would be the voltages. Buffers may be required to keep the voltage from drooping too much. Also, there may be issues with the welder itself. Does it allow live changing of the current setting? The welder may lock the setting while the weld is occurring. \$\endgroup\$
    – vini_i
    Oct 1, 2019 at 19:39
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    \$\begingroup\$ Thanks for the reply. I forgot to mention that. Yes it does allow live changing of the current. When I turn the knob during welding it will drop the amperage without stopping the welding. If I were to just put the potentiometer in the foot pedal It would work. I just won't be able to set a limit on the current. Full pedal would max the machine out at 200 amps. Let's say I turn te pot on panel to 120 amps. Then I want the pedal to only go to 120 amps when fully pressed and slowly drop down when I let off. \$\endgroup\$
    – Aph
    Oct 1, 2019 at 20:10
  • \$\begingroup\$ Definitely use shielded cable between the footpedal and welder. Otherwise these could pick up electrical noise. \$\endgroup\$
    – rdtsc
    Oct 2, 2019 at 0:57
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    \$\begingroup\$ arcing of the welding current may induce absurdly high voltage spikes into your wiring, either by dI/dT magnetic fields or by dV/dT electric fields. What level of induced voltage noise will the circuit tolerate? How to include a low-pass-filter R+C to reduce the induced spikes to safe level? \$\endgroup\$ Oct 2, 2019 at 4:12
  • \$\begingroup\$ Hello Was the conversion successful? Do you know how to set it up and adjust it? If it worked, do you have any pictures or the like of how to do it? Thank you :) \$\endgroup\$ Dec 27, 2021 at 21:02

1 Answer 1


I have not thought I would need to adjust the current while welding. But it sounds like a good idea. Honestly, I am only a beginner, stick welder.

Compliment to your schematics drawing skill as a welder. Soon, welders will take over EEs' job.
Anyway, this is the electrical symbol for your last try.


simulate this circuit – Schematic created using CircuitLab

Firstly, "I can only see and set the max amperage when the pedal is fully pressed." is likely coming from your pedal turns the wiper (internal part of pin number 2) toward pin #3. Swap pin 1 & 3 of the pot on the pedal. And then see if that fixes

Secondly, For "it won't go as low as it used to due to incorrect potentiometer value". Use 10K (B103) for foot pedal, and see it improves. Now, along with the B103 on foot pedal, try 2K2 (B222) on the range setting, if that improves.

Now, in order to find the optimum values, and correct configurations:
a) Check the original front panel pot has pin 3->red, pin 2->blue, pin1->black, indeed as your drawing implies.
b) Measure the resistance of the original front panel pot (that you are trying to replace) across pin 1 & 3.
c) Measure that resistance of the original pot pin 2 & 3, and check if the resistance increases or decreases while turning the pot clockwise (higher current setting).
d) Post that here, please.

Assume that the "Firstly" and "Secondly" worked, then, this is what would make it work even better (may be?). The cable is 3 wire in shield.


simulate this circuit


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