High Voltage High Frequency Circuit for welder unit question

Papabravo

Joined Feb 24, 2006
22,082
I am not a welding type and if you saw some of my weldments it would be apparent. I did have the pleasure for about 25 years of working with some of the best nuclear class welders around. Welding and really great welding is an art form. Nobody picks up a stick and makes a perfect beautiful weldment the first time around. It can take years of practice to start making good welds. That is the nature of the beast. It's a skillset that is developed and many start by welding scrap pieces together. Before we got really nice new stuff our guys were turning out really work on 1960s vintage machines They constantly developed their skills and that takes patience and practice.

Shortbus is likely the mostcompetent guy here to discuss welding so really give him a shot. He knows his stuff. He is one guy you want to listen to.

Good Luck
Ron
As a young engineer, I was a witness to and a participant in the efforts of an extraordinary group of individuals with diverse technical skills that took years to develop. We could not have accomplished the things we did without their skill and patience. For all of that they made far less than today's minimum wage. Such a pity.
 

Thread Starter

psoke0

Joined Mar 31, 2017
205
Like our help or not it is what we've spent a lifetime finding out. Personally I'm 74 years old and have been doing this stuff since I was around 14 years old. What your wanting won't make stick welding any better or easier. For body work (which I've done a lot of) a oxy/actet welder is much better than stick or even Mig. While the HAZ is a little bigger the weld is easier to work down, not as hard.
i was thinking if i can make that feature i will also buy argon gas. because i have the tig torch too . i may make the lift start feature its will be better then scratch start i guess
 

shortbus

Joined Sep 30, 2009
10,050
Some things to think about. It kind of sounds like your working out side, if so Tig isn't the way to go. Any slight wind will blow away the gas shield and welding won't work without a gaseous shield. Argon will be your most expensive consumable, at least it is around here. You will also need a gas regulator and for scratch or lift start most times you have a torch with the gas valve built into it, if not you need some type of solenoid valve to turn the gas on when you strike the arc.

Here is a guy showing how to Tig using scratch start.

Didn't watch this one clear through, but from previous videos the Eastern European guys are pretty good mechanically and believable in what they do.

I had some DIY tig stuff bookmarked but never made a folder so will have to look for them. I only saved the ones that looked plausible.
 

Papabravo

Joined Feb 24, 2006
22,082
Damn what a mess. All guy wanted to know was how to decouple hf high voltage from dc low voltage - and you had to go and tell him about all this dumb s.


If you cannot take or use said advice, then it's not good advice. By definition. It's like telling a cancer patient "dude dying will make your family sad, you shouldn't do it" and calling it good advice.
Would have been good advice if you actually gave him advice and then advised him on the dangers involved. Plus, his question was about how to join the high voltage to the inverter circuit, so it is assumed that he already has the high voltage - and he's not dead. So it's also condescending.


Well, except every chinese manufacturer that pops up every week with a new welder.


It does not. Inverter welders rectify the mains voltage, and then switch it at a few khz, which makes it so that a smaller transformer is needed. They also vary the duty cycle of that switching to vary the current output. The transformer is still there to get down to the ~40v needed, and after that it's rectified by fast diodes. Many welders have no inductor after the diodes, but the switching frequency is so fast anyway that the air doesn't have time to deionize and cool enough to interrupt the arc.


"Waste". Man has already said he doesn't have the money. Maybe he works a dead-end job that pays worth a s, and he wants to be a welder who can also do tig and put some food on the table. You're just being a d now. Missed the perfect opportunity to not say anything.


Where the f you live maybe. And even then, lincoln welders go for 2000 bucks where the chinese make the same thing for 600. And you can get the components from scrap. The transistors and diodes in a decent welder are cheap enough that if you had access to old CRT monitors alone, you could make a very capable inverter tig welder for a fraction of that price. Can you not use your head? Or are you incapable of putting yourself in someone else's shoes?


He's asking you how not to ruin what he has.
And if you did that much welding, you'd know there's some amperage ranges where tig scratch start is basically impossible. Not to mention you'll always contaminate and ruin your tungsten. Not everyone is after that buddy, which is why hf even exists in the first place.


Get your head out of your ass. You clearly don't know enough to help him and now are just coping with him calling you out on your garbage "advice". These aren't "additional circumstances", these are constraints - he has to work within them, and his question to begin with already included such constraints. You could not come up with a solution that will meet his constraints. Also you're the one whining here, and you're the one who should help yourself.


"Help". Lol. Also doing stuff for 50 years doesn't mean anything if you've been doing it wrong for 50 years. Arguments of authority don't work and they never have. Nobody welds with oxyfuel anymore. It's not better than stick or mig, not by a long shot. Especially not if you're trying to make a living from it. At best brazing might be better, but even that you can still do with tig. Plus not risking blowing up your house or workplace is nice, and not spending thousands on equipment so that you won't is also kind of a plus. You're right that stick won't work (not well anyway), but that should have been a note left on the end of some actual help.


Yeah well, I doubt our friend here is looking to weld nuclear-class tomorrow.
It only takes you years of practice to make good welds if you're practicing a total of 1 second per day and you have no access to the internet.


I mean let's be real, the welding in this video will cost you 30 to 50 bucks in tungsten at the end of a day if this is your job.
And the second video is nice but it doesn't solve the initial question of how not to burn your welder. The solutions online seem to just be for transformer welders (all that I've found anyway, google seems like it's been getting worse and worse because I can't even find the blog posts and stuff that I read months ago - duckduckgo is actually working better, which is how I found this thread).

-------------------------

Lastly, I'd like to add in my 2 cents. I'm trying to do the same thing because I for one have time but not that much money and it's good learning and good fun.
From what I've looked at so far, if you manage to find a few old broken CRT TVs, you can use the flyback to generate the high voltage at decently high frequencies (they seem to run from 20khz to 50khz). The TVs also have some high voltage caps and some decent length thick copper wire. Really the main trouble is isolating the HFHV from the welder supply that is DC high current and low voltage.
I'll be getting a pilot arc plasma cutter soon, and I'll open it up to see how they do it, but from what I understand it's little more than just an inductive choke to decouple hf before the inverter stuff. I'm thinking of just using the thick wire from some CRTs I scavenged some time ago to make a coil. I suspect it'll be enough, but if not I'll just rip some cables off the wall : P .
If you manage to attenuate the voltage to bellow the reverse voltage of the output diodes, then it shouldn't be able to do any harm at all.
Before the arc is struck it won't be able to flow anywhere because the diodes will stop it, and after the arc is struck it'll have almost a short through it so it will barely even touch the welder.
That's what I figure anyway. This is my first post here so if it doesn't get deleted or I don't get banned for it, I might write on my findings when/if I try it out. Short on time at the moment.
If you play a country song backwards, you get your dog back, your wife back, and your truck back.
 

shortbus

Joined Sep 30, 2009
10,050
This is my first post here so if it doesn't get deleted or I don't get banned for it, I might write on my findings when/if I try it out.
You sure know how to make a first impression. Your opinions of people that have done things for years is just your opinion. Feel free to keep quite.
 

Reloadron

Joined Jan 15, 2015
7,886
I thought it was dog! Have I been misinformed?
No, that's true but only for country music. :)

In keeping with topic:

While I was not a weld engineer I worked with several large systems. Mostly Lincoln Electric and AMI (Arc Machines Inc). When doing an automated HF start the HF was induced using a transformer. The instruments measuring were downstream of a choke (Inductor). Worked with some stuff dating back circa 60s.

Ron
 

bassbindevil

Joined Jan 23, 2014
922
I've seen add-on high frequency units at vintage car swap meets. Now is the season; go to the big ones, get there first thing in the morning and you might get lucky. (And, you can always find oxy-acetylene gear; I scored a Henrob (aka Dillon or Cobra) mini torch kit for $15 (and that was at the end of the day).)
 

shortbus

Joined Sep 30, 2009
10,050
I've seen add-on high frequency units at vintage car swap meets. Now is the season; go to the big ones, get there first thing in the morning and you might get lucky. (And, you can always find oxy-acetylene gear; I scored a Henrob (aka Dillon or Cobra) mini torch kit for $15 (and that was at the end of the day).)
Those old add-ons were for transformer welders, don't know how they would work with the new invertor welders though.

That was a steal on the Cobra/Dillon. I have one, bought it when they first came out, but getting used to the pistol grip style is not easy, at least it wasn't for me.
 

shortbus

Joined Sep 30, 2009
10,050
"3BeFair said:

This is my first post here so if it doesn't get deleted or I don't get banned for it, I might write on my findings when/if I try it out."

Since his post got deleted we might never find out how great he is. :)
 
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