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Groups > sci.electronics.design > #453870 > unrolled thread

tig hi freq

Started byHul Tytus <ht@panix.com>
First post2017-03-27 14:17 +0000
Last post2017-03-31 15:35 -0400
Articles 9 on this page of 29 — 13 participants

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  tig hi freq Hul Tytus <ht@panix.com> - 2017-03-27 14:17 +0000
    Re: tig hi freq George Herold <gherold@teachspin.com> - 2017-03-27 08:00 -0700
      Re: tig hi freq Hul Tytus <ht@panix.com> - 2017-03-27 16:15 +0000
        Re: tig hi freq tabbypurr@gmail.com - 2017-03-27 09:40 -0700
        Re: tig hi freq Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-03-27 09:45 -0700
          Re: tig hi freq Bill Martin <wwm@wwmartin.net> - 2017-03-27 10:24 -0700
            Re: tig hi freq Neon John <no@never.com> - 2017-03-31 15:27 -0400
              Re: tig hi freq Bill Martin <wwm@wwmartin.net> - 2017-03-31 14:42 -0700
        Re: tig hi freq "dcaster@krl.org" <dcaster@krl.org> - 2017-03-27 11:22 -0700
        Re: tig hi freq George Herold <gherold@teachspin.com> - 2017-03-27 11:37 -0700
      Re: tig hi freq Neon John <no@never.com> - 2017-03-31 15:01 -0400
    Re: tig hi freq Tim Wescott <tim@seemywebsite.com> - 2017-03-27 12:19 -0500
      Re: tig hi freq "dcaster@krl.org" <dcaster@krl.org> - 2017-03-27 11:15 -0700
        Re: tig hi freq Hul Tytus <ht@panix.com> - 2017-03-27 22:56 +0000
      Re: tig hi freq amdx <nojunk@knology.net> - 2017-03-27 14:54 -0500
      Re: tig hi freq Hul Tytus <ht@panix.com> - 2017-03-27 22:55 +0000
    Re: tig hi freq Cursitor Doom <curd@notformail.com> - 2017-03-27 18:33 +0000
      Re: tig hi freq Hul Tytus <ht@panix.com> - 2017-03-27 22:57 +0000
        Re: tig hi freq Chris Jones <lugnut808@spam.yahoo.com> - 2017-03-28 18:07 +1100
          Re: tig hi freq Neon John <no@never.com> - 2017-03-31 15:50 -0400
    Re: tig hi freq Jon Elson <jmelson@wustl.edu> - 2017-03-27 14:02 -0500
      Re: tig hi freq Hul Tytus <ht@panix.com> - 2017-03-27 23:07 +0000
        Re: tig hi freq Jon Elson <jmelson@wustl.edu> - 2017-03-28 13:51 -0500
          Re: tig hi freq Hul Tytus <ht@panix.com> - 2017-03-28 22:04 +0000
            Re: tig hi freq sroberts6328@gmail.com - 2017-03-29 06:55 -0700
              Re: tig hi freq sroberts6328@gmail.com - 2017-03-29 07:01 -0700
                Re: tig hi freq sroberts6328@gmail.com - 2017-03-29 07:15 -0700
                  Re: tig hi freq Hul Tytus <ht@panix.com> - 2017-03-29 15:05 +0000
      Re: tig hi freq Neon John <no@never.com> - 2017-03-31 15:35 -0400

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#453910

FromJon Elson <jmelson@wustl.edu>
Date2017-03-27 14:02 -0500
Message-ID<67SdnTyr9LXv_ETFnZ2dnUU7-YXNnZ2d@giganews.com>
In reply to#453870
Hul Tytus wrote:

> sci.electronics.design
> tig high freq
> 
>    Does anyone here know what the frequency & initial voltage is of the
>    "high
> freq ac" used in TIG welders? Google's offerings seem to favor client's
> advertising and "how to weld" documents, unfortunantly.
The typical setup on older welders is a spark gap Tesla coil, so there is no 
control of frequency.  A several thousand Volt transformer charges a 
capacitor at 60 Hz frequency, that voltage creates sparks that dump the 
capacitor into the Tesla coil primary.  So, the output is generally bursts 
of 10-20 KHz spikes repeated at 120 Hz.

Some newer welders have electronic drive for this, so they have a defined 
frequency.

The HF on a TIG welder ought to be at least 10 KV, and maybe up to 20 KV.

Jon

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#453928

FromHul Tytus <ht@panix.com>
Date2017-03-27 23:07 +0000
Message-ID<obc5vf$h9j$4@reader1.panix.com>
In reply to#453910
Jon - any suggestions on which of the newer tig welders has the more 
modern hi freq drive?

Hul

Jon Elson <jmelson@wustl.edu> wrote:
> Hul Tytus wrote:

> > sci.electronics.design
> > tig high freq
> > 
> >    Does anyone here know what the frequency & initial voltage is of the
> >    "high
> > freq ac" used in TIG welders? Google's offerings seem to favor client's
> > advertising and "how to weld" documents, unfortunantly.
> The typical setup on older welders is a spark gap Tesla coil, so there is no 
> control of frequency.  A several thousand Volt transformer charges a 
> capacitor at 60 Hz frequency, that voltage creates sparks that dump the 
> capacitor into the Tesla coil primary.  So, the output is generally bursts 
> of 10-20 KHz spikes repeated at 120 Hz.

> Some newer welders have electronic drive for this, so they have a defined 
> frequency.

> The HF on a TIG welder ought to be at least 10 KV, and maybe up to 20 KV.

> Jon

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#454021

FromJon Elson <jmelson@wustl.edu>
Date2017-03-28 13:51 -0500
Message-ID<itKdneDUsITiLUfFnZ2dnUU7-YWdnZ2d@giganews.com>
In reply to#453928
Hul Tytus wrote:

> Jon - any suggestions on which of the newer tig welders has the more
> modern hi freq drive?
Well, if it is the size of a lunchbox, it must be the modern style.

I have an 800 Lb Lincoln Square Wave TIG 300, so that is definitely the OLD 
style.  It is the size of a small fridge.  The HF is strong enough you can 
weld really thin stuff with just HF!

Jon

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#454045

FromHul Tytus <ht@panix.com>
Date2017-03-28 22:04 +0000
Message-ID<obemlm$os7$1@reader1.panix.com>
In reply to#454021
Jon - good gage. I'll keep that in mind.

Hul

Jon Elson <jmelson@wustl.edu> wrote:
> Hul Tytus wrote:

> > Jon - any suggestions on which of the newer tig welders has the more
> > modern hi freq drive?
> Well, if it is the size of a lunchbox, it must be the modern style.

> I have an 800 Lb Lincoln Square Wave TIG 300, so that is definitely the OLD 
> style.  It is the size of a small fridge.  The HF is strong enough you can 
> weld really thin stuff with just HF!

> Jon

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#454118

Fromsroberts6328@gmail.com
Date2017-03-29 06:55 -0700
Message-ID<ddba85c2-d741-431d-a40f-1b11d8d714f8@googlegroups.com>
In reply to#454045
Its a small tesla coil with some inductors and caps added to the welding circuit. A low pass LC or just an L capable of carrying the weld current keeps the HF out of the welder and/or rectifiers.  A spark gap or special mica capacitor  is used in older systems to couple the HF to one electrode, modern systems may have the Tesla secondary carry the weld current.   

In the old days it was HF on or off. Now they time/gate  the RF burst for various purposes by modulating the power to the Tesla primary.

Basically anywhere from 50 to 300 KHz, very high peak voltage, beefy tesla.
 coil. 

How do I know, well, Big Xenon Arc Lamps need very similar starters and similar protection schemes for the DC power supply.. I spent a few days designing  suitable LC low pass filter and shunt capacitors to keep the HF into the lamp and out of the PSUs output FETS. Then it was off to design a decent spark gap. Spark gaps do a better job then diodes at coupling the HV into the anode lead..

 For example, series injection transformers for starting krypton lamps in lasers and xenon lamps in Medical IPL systems often have secondaries that can handle 100 or more amps, so the technology is out there...
 
-----------------------

See: 

http://www.arcpig.com/faq.html

Steve

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#454119

Fromsroberts6328@gmail.com
Date2017-03-29 07:01 -0700
Message-ID<bc4077e6-4095-4dcf-bb8e-f25f6d079c29@googlegroups.com>
In reply to#454118
Here is a link to the classic HF source manual.. A small AC HV transformer drives a Tesla style resonant transformer which provides the HF...

http://www.esabna.com/literature/archive/manual/f-9500%20-%20f-9999/f-9878-b_high-frequency_generators.pdf

Steve

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#454120

Fromsroberts6328@gmail.com
Date2017-03-29 07:15 -0700
Message-ID<e8adec88-a5a4-4a1d-98f2-901980618211@googlegroups.com>
In reply to#454119
US patent 2840761  drops some hints, and will link you to similar patents on the patent server if you use "Google Patents"..

Here is a small, modern, implementation...

http://www.wseas.us/e-library/conferences/2006prague/papers/513-109.pdf

Steve

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#454124

FromHul Tytus <ht@panix.com>
Date2017-03-29 15:05 +0000
Message-ID<obgiff$ks$1@reader1.panix.com>
In reply to#454120
Thanks for the links Steve. I'll have alook at them.

Hul

sroberts6328@gmail.com wrote:
> US patent 2840761  drops some hints, and will link you to similar patents on the patent server if you use "Google Patents"..

> Here is a small, modern, implementation...

> http://www.wseas.us/e-library/conferences/2006prague/papers/513-109.pdf

> Steve

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#454458

FromNeon John <no@never.com>
Date2017-03-31 15:35 -0400
Message-ID<ufbtdchtpt2a32igtn3gpkbc4mmim9q581@4ax.com>
In reply to#453910
On Mon, 27 Mar 2017 14:02:19 -0500, Jon Elson <jmelson@wustl.edu>
wrote:


>The typical setup on older welders is a spark gap Tesla coil, so there is no 
>control of frequency.  A several thousand Volt transformer charges a 
>capacitor at 60 Hz frequency, that voltage creates sparks that dump the 
>capacitor into the Tesla coil primary.  So, the output is generally bursts 
>of 10-20 KHz spikes repeated at 120 Hz.

It NOT a Tesla coil.  No resonant secondary.  It's a good old
fashioned series resonant spark gap oscillator with the output coupled
to the welding lead.  And the frequency is in the quarter MHz range.
If the frequency were as low as you say, it would be an audible
screech!

John
John DeArmond
http://www.neon-john.com
http://www.tnduction.com 
Tellico Plains, Occupied TN
See website for email address

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