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Harbor Freight TIG - Adding a foot pedal

Came across a good deal on a Thermal Arc foot pedal - it has a 5 K pot. The current control on the front panel of the HF Tig is a 10K. It is wired up as a pot (not a rheostat) - my plan is just to add a connector and a switch to the front panel and use that to choose which control to use. Anybody have any idea of the inner workings of this beast? Would the 5K pot in place of the 10K cause any problems? I'm tempted just to wire it up and see what happens. The schematic in the manual is leaves a lot to be desired.

thanks in advance for any advice

Mike

Reply to
Mike
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Use an audio style connector, and it could automagically switch the panel control out for you, and switch the pedal in.

No having the proper schematic would make me nervous to just suggest trying it: sure, if I designed it, it would be a buffered signal and the pot value wouldn't make any difference, but....

Can't you change the pot in the Thermal Arc ?

Steve

Reply to
Steve Taylor

By 'wired up as a pot' you mean all three terminals on the pot are used? If so it'll likely be a classic voltage divider circuit. The 5k pot would draw twice the current from the control circuit, but given the high resistance, I doubt it'd cause any issue.

I've been looking to do the same mod on my unit, but haven't found a rugged pedal yet. What are the thoughts on the sensitivity of the foot pedal if wired for full-range control? Would a primary panel adjustment with foot pedal for 'trim' adjustment be worth considering?

Out of curiousity, what gas flow rate are you using on your unit? I've been running 15 cfh, but find the tungsten balls up fairly quickly. I'm wondering if cranking up the gas flow rate will drop the temp enough to prevent that problem.

Roger.

Reply to
renns

Thanks for the response - I thought about that, but it's a brand new pedal and I'm a little reluctant to tear into it if I don't have to. However that does probably beat the alternative of reducing the HF unit to a charred cinder............

Mike

Reply to
Mike

As the other guy said, its probably just a pot, but unless you trace it out, you can't be sure. Is it worth the risk ? I doubt you'll break anything.

Steve

Reply to
Steve Taylor

You could put a 2.5K resistor in series with each end of the pot, or some combo that adds to 5K. You would not have the entire range of control you would normally have, but perhaps you can find a happy medium. OTOH, I would try the 5K. Jim.

Reply to
Jim L.

Reply to
Robert Ball

I have added a foot control to mine. I used a guitar volume pedal off eBay and switched the pot out. You need a 10k pot, as the control uses both sides of the pot, it doesn't work with the wrong range. Having the full range of amperage available on the foot pedal is a bit much for the thin sheet metal I want to use mine for, so I have been experimenting with a range control.

I first used fixed resistors to see how it worked with two ranges, then went to a full range control on the panel.

You need to get a duplex pot (two 5k pots on a common shaft) and wire them so one pot goes in each leg of the foot pedal with the center taps common. This goes in the control panel and gives you your range. All the way down on the panel pot and the foot pedal gives 0-60 amps, and all the way up it is 60-120 amps (or whatever, I forget the exact amp range of the welder).

It's been a while since I made it with the help of an electrical engineer, so I'm a bit fuzzy on the details right now.

Dennis

Reply to
DT

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