Re: autotransformereffect

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

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

currently considering cutting it down to just over the used turns...
Im looking at all avenues to improve the performance of my little coil...

a bit of info
I am planning on building a MMC to replace
2x 7.5 nf bucket capacitors
modeled after the geek bucket caps but... built with 8x 1.5 liter wine
bottles..4x each bucket.

I may upgrade my vacum suction gap to some type of syncronous rotary gap.
I may buy 2 more NST and try for 12000v 30ma, to bring the total to 4x or
12kv 120ma.
I may wrap a new 8" secondary which will mount into the current primary
configuration...
The inner diameter of my primary is abouy 9 1/2 inches... (I pleed ignorance
in the construction..... I wasnt aware of the power / tuning
relationship.... or the fact that you could just add more amps and drop the
tuning point closer to center.....

Just not sure what to do next.... hell it works good now...
ah who am I kidding it could always work better
thinking effeciency..

Chris Dowdy

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, July 30, 2002 3:15 PM
Subject: RE: autotransformereffect


> 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
>