Re: gaps on caps

From: 	John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: 	Thursday, January 08, 1998 11:01 PM
To: 	Tesla List
Subject: 	Re: gaps on caps

At 08:06 AM 12/31/97 +0000, you wrote:
>From: 	Kevin Wahila[SMTP:wawa-at-spectra-dot-net]
>Sent: 	Sunday, December 28, 1997 5:10 PM
>To: 	tesla-at-pupman-dot-com
>Subject: 	gaps on caps
>I have a safety gap across my capacitors.  What I want to know is, what
>is my Tesla Coil telling me when this safety gap fires?  It's not like
>it fires nonstop, but it does so it every so often and sometimes more
>than others.


  Kevin -

  I did not see any comments on this subject or did I miss them?

  This is an interesting part of TC operation that apparently little is
known. Tesla in the CSNotes mentioned the fact that tremendous power (not
energy) could be produced in the TC but he did not eleborate or give
details. It is obvious from the erratic operation of the safety gap that
power or energy in the primary circuit is not the same at each bang. This is
why the secondary sparks are not always the same length and why those rare
extra long sparks occur. 

  It appears that the charging of the primary capacitor is actually charging
to different amounts of voltage at each bang. This could cause the safety
gap to fire at certain times. The different amounts of primary charging are
dependent on the operating spark gap. The major characteristics of this gap
that would affect the amount of charging are resistance and time of closure.
I do not believe these characteristics have ever been researched and tables
or graphs published for Tesla coils. I have seen articles on spark
characteristics but they do not have any relation to Tesla coil operation. 

  It should be noted that the operating spark gap can produce large
transient voltages or pulses. These transients require very little energy
but can trigger the safety spark gap causing it to fire and make a loud
noise (high power). These transients can also damage the power transformer
especially the neons. This is why safety gaps across the transformer output
are recommended. Putting the operating spark gap across the neon output is
risky business as there is no voltage limiting.

  You may have to wait awhile before you or any coiler can find out what the
safety gap it telling us. 

  John Couture