Re: Welder ballasts vs. other types

• To: tesla-at-pupman-dot-com
• Subject: Re: Welder ballasts vs. other types
• From: FutureT-at-aol-dot-com (by way of Terry Fritz <terryf-at-verinet-dot-com>)
• Date: Tue, 13 Oct 1998 08:00:01 -0600
• Approved: terryf-at-verinet-dot-com

In a message dated 98-10-13 01:28:31 EDT, you write:

<< 
> There was a neat analysis done by an engineer named Jamieson some 
> time back which investigated the causes of firing jitter in TC 
> designs. It turned out that the real problem was the charging circuit
> resonance not matching that of the breakrate. In fact it was more 
> complex. There were beating effects going on between the mains 
> frequency, the charging L/C frequency and the rotary gap firing 
> frequency. The program which also had a .doc file with it was named 
 >"ROTJIT". Someone here might have a copy. I don't know where mine is
> but could probably find it if necessary.
 
> Malcolm
  >>

Malcolm, all,

I've read an article by Jamieson, and I've seen the free (parameters
fixed) version of his program.  I wonder if the whole ballast question,
(the need or lack of need for resistors, etc), boils down to these
beating issues you mentioned.  In cases where the beating is
"unfavorable" then resistors would be needed to dampen the
resonances, whereas in TC's chargers that happen to have favorable
beating characteristics, resistors wouldn't be needed?  Or is there
something about a welder...(some sort of self-damping?) that makes
it "better"?  Are the variacs, or other ballasts being used often too
"good", (too loss-free), thereby contributing to the beating problem?

Thanks,
John Freau

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