Superultra 205 Tig Pedal

[Jeff9]

Well, you are 100% correct, Rambozo... Talked to Oleg and he is sending me a 160 STH. That is what customer service looks like!! I am very grateful!

[Jeff9]

Well, you are 100% correct, Rambozo... Talked to Oleg and he is sending me a 160 STH. That is what customer service looks like!! I am very grateful!

Hi Oleg,
Received the 160STH yesterday and tried it out today. Love the foot petal to control the arc!

Thank you again for getting me the correct Machine even though Amazon screwed up the fulfillment!

Kindest regards,
Jeff9

[Jeff9]

Well, I might have spoken too soon. Love having a foot pedal for Tig operation, but this one is very difficult to adjust max amperage. Just the slightest adjustment on the pot knob located on the pedal, and you go from 85 amps to 160.. May be returning the pedal if I find a better pedal.

I have seen people post going with SSC Controls foot pedal.

[zoama]

I have seen people post going with SSC Controls foot pedal.

Everlast sells it also.

[Jeff9]

Everlast sells it also.

Thank you Zoama

[joshuab]

Jeff,

I have studied this problem with the max-output pot in some depth. You can find my posts on the topic on this forum with a little searching. In summary, whenever you have two pots wired up like the pedal is, you end up getting some non-linearity in the response. The folks at Everlast have tuned the pedal's max-output dial to be more sensitive at the bottom of the range, since you are more likely to end up wanting to limit max output when working at low amperage.

One way to approach this is to just pretend the max-output pot isn't there when working over about 85-90 amps, and use the pedal for control. Another way to approach it is to wire up an op-amp between the max-output pot and the pedal pot. This should prevent the max-output pot from loading down the pedal pot, however it will require an external power supply, or it will require an op-amp that can run off the power supplied from the welder to the pedal. The welder supplies 2.7 volts to the pedal when on 110v power, and 5 volts when on 220v power. A third approach would be to replace the max-output pot with a different value. This will produce different response curves, and you should do some calculations to be sure that the resulting response of the pedal will work for you.

Regardless, changing to a different pedal won't fix the problem. Most pedals don't have a max-output knob like this. They expect the welder to handle the max-output control, as most of them do.

What I ended up doing for the project is building a box with a microcontroller in it to sit between the pedal and the welder. The box allows for proper max-output control, as well as adding 4T operation and pulsing up to about 30 Hz. The parts for the box run around $200. When I ordered circuit boards, the minimum order was three, so I have two extras that I don't really need. The rest of the parts can be ordered off the Internet. If you are handy with a soldering iron I can provide you with the schematic and some photos, as well as the code to upload to the microcontroller. It's an ambitious project. Even though I've worked out most of the kinks, if you don't have at least some familiarity with electronics and computer programming, you'll probably have problems. But if you're interested, I'm game.

Here's one of the videos I uploaded demonstrating the box in action:
https://www.youtube.com/watch?v=NlcVbCdZVLQ

[Rambozo]

Another route instead of an op-amp would be to just add an adjustable LDO voltage regulator to lower the incoming 2.7-5 volt reference voltage. Then you would use the max power pot to adjust the voltage. That would not require a power supply and you could switch it out of circuit at the max setting so you would not have any drop out voltage issue. There would a very small step near max power, when you switch it out, but the rest of the range would be totally linear. I bet the whole circuit would be $5 -$10 tops and simple enough to do on perfboard or even point to point on the back of the pot.

Of course just running on 120 for low range and 240 for high range is all I've ever needed, as I don't tend to work with the pedal "floored", but I know some people prefer that.

[joshuab]

Another route instead of an op-amp would be to just add an adjustable LDO voltage regulator to lower the incoming 2.7-5 volt reference voltage. Then you would use the max power pot to adjust the voltage. That would not require a power supply and you could switch it out of circuit at the max setting so you would not have any drop out voltage issue. There would a very small step near max power, when you switch it out, but the rest of the range would be totally linear. I bet the whole circuit would be $5 -$10 tops and simple enough to do on perfboard or even point to point on the back of the pot.

That's pretty clever. Goes to show how you should always solve the real problem (my max-output knob is non-linear), not the thing that is causing the problem (one pot is loading down another).

[Jeff9]

That's pretty clever. Goes to show how you should always solve the real problem (my max-output knob is non-linear), not the thing that is causing the problem (one pot is loading down another).

Joshuab & Rambozo,

Thank you for the responses. Very cleaver on both your ideas and work! So, if purchasing a higher end pedal won't solve the upper end control, I'll just learn to work with what I have. I really like the 160STH and the value.

Kind regards,
Jeff9