RE: autotransformereffect

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

The only thing that builds up in a Tesla coil over a period of several
seconds is the temperature of the gaps.  But I can't explain why hot gaps
would cause the safety gaps to fire.  I would have guessed the opposite to
be true - a hot gap would fire at a lower voltage, making the safety's less
likely to fire.

Or, is your capacitor using a ceramic dielectric that may heat up and
detune?  This may cause safety's to fire.

I see no connection between the time delay to when the safety's fire and
your large number of unused primary turns, but it is possible that very
high frequency resonances in the unused turns are set in motion each time
the main gap fires.  No one has really looked into this but it's remotely
possible that such resonances could have unforeseen consequences.  I
wouldn't want to do it to mine but I'll ask anyway - Would you consider
cutting your primary to isolate the unused turns and see if the problem
persists?  You have many more unused turns than normal and this is
uncharted territory.

Regards, Gary Lau
MA, USA



Original poster: "cd by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<vbprg1-at-hotmail-dot-com>

ok let me ask a quick question
I have been told that since i built a large 20 turn primary and I am taping
it at the 9th turn 11 turns hanging out untaped each one bigger than the
last.
I am wondering..
When I run the coil after about 30 to 60 seconds
I start to get shots across the safety gap
untill I turn the power down to about 90 percent..
I have been told that
some of the over sparking in the primary outer turns is due to
autotransformer effect voltage building up in the unused turns...This is
pretty apparently sometimes the cause of sparks jumping across the safety
gap, but I am getting fires in the safety gap without over sparking of
anykind in the outer turns...
So I am wondering is the auto transformer effect creating the voltage surges
that fire the safety gap or is there some kind of increase in voltage during
the operation of a coil???
Some kind of secondary to primary feedback loop????
Im just talking about when
the safety gap is firing without outer turn over sparking and no association
with strikes to primary or strike rail...

it only seems to happen after I have run the coil for at least 30 seconds
leading me to believe some type of voltage buildup is fireing the safety
gap....

*a note the safety gap will not fire at all on the nsts alone...and is
widened a bit more than just a hair from when it would fire... so they are
probably large voltage surges or increasing voltage build up untill it
fires...

Kinda wierd actually... thought I had it all tuned right....

Thanks
Chris Dowdy