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Arduino? and a tig welder conundrum.
BenH:
Hey all,
I've recently picked up a Rtech AcDc tig and most importantly a good price on CK torch with built in rotary amperage control. Now I knew the R tech would need a 47K pot for the input and the CK torch is a 10K, they don't do a 47K or indeed anything close and the CK price make my eyes water too!
Plan A was maybe to find a suitable slider pot to mod, but again 47k is hard to find a slider and impossible in the correct travel and with switch. So plan B is use the 10k pot to input to a Arduino, then have that control RC type servo or stepper motor linked to a 47K pot going into the tig.
Does that sound like a feasible plan or do any one have a better suggestion? It's been while since I programmed anything but kind of sounds a interesting thing to try :beer:
garym:
Hi Ben,
I might be mis-understanding you as I don't know anything about welders but why can't you get a 47k pot. There are 24 types on here:-
http://uk.rs-online.com/web/c/passive-components/variable-resistors/potentiometers/?applied-dimensions=4294466037&esid=cl_4294967294,cl_4294584764,cl_4294956547,cl_4294956056,cl_4294956957,cl_4294957317&m=1&sort-by=P_breakPrice1&sort-order=asc&pn=1
Gary
awemawson:
Arduino far too complicated. Use a FET as a voltage controlled variable resistor and use the 10K pot as your voltage source suitably scaled to make the FET look like a 47k resistor
http://freespace.virgin.net/ljmayes.mal/comp/vcr.htm
BenH:
--- Quote from: garym on May 11, 2014, 02:28:39 PM ---Hi Ben,
I might be mis-understanding you as I don't know anything about welders but why can't you get a 47k pot. There are 24 types on here:-
http://uk.rs-online.com/web/c/passive-components/variable-resistors/potentiometers/?applied-dimensions=4294466037&esid=cl_4294967294,cl_4294584764,cl_4294956547,cl_4294956056,cl_4294956957,cl_4294957317&m=1&sort-by=P_breakPrice1&sort-order=asc&pn=1
Gary
--- End quote ---
Hi Gary,
Yeah a new pot would be perfect, but alas none will fit. As they say a picture says a thousand words so the first up is the torch and hand control it self, the 2nd is the pot itself. As you can see it would need to fit in the handle, have the correct travel (20mm total) be switched as well to fire up the tig. I notice also the first part of the travel has no resistance, I suspect to make it easier to use perhaps.
CK do other values as well, but only 1k 5k 10k and 25K, they want £110 for one of those little switch/ pot things!
BenH:
--- Quote from: awemawson on May 11, 2014, 02:45:47 PM ---Arduino far too complicated. Use a FET as a voltage controlled variable resistor and use the 10K pot as your voltage source suitably scaled to make the FET look like a 47k resistor
http://freespace.virgin.net/ljmayes.mal/comp/vcr.htm
--- End quote ---
That sounds interesting I'll have to do some reading and testing, I know the tig see's all 3 legs of the pot but not knowing what's going on inside makes me a little nervous (thoughts of magic smoke leaking out). I'll dig out the box of components and breadboard something up and see what happens, the thing that I like about using a servo driven pot is that if I get it wrong the tig is isolated electrically from whatever I make.
Maybe a simple servo controller would be better than a Arduino, I did find one that could follow a control pot but cant think where now..
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