chokes-new question

From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent:  Monday, June 01, 1998 6:09 PM
To:  Tesla List
Subject:  Re: chokes-new question

Hi all,
         I fired a small coil this weekend using a 5kV 30mA NST. I 
used *no* fitering components at all. The transformer to gap leads 
were just a few inches long. The gap is effectively hard up against 
the transformer terminals. It was set to fire at 7-8kV. Charging was 
resonant but not pure as the primary cap on hand was a bit too high a 
value to exactly hit mains resonance. I got nice 12" air streamers 
off the coil. The primary was dreadfully lossy and I expect much 
better once the driver is oil-submerged to eliminate coronas. 
Resonant charging was evidenced by the 2-3BPS gap firing at a 30% 
variac setting.
     The point I would make with regard to filters is that if the 
main gap is virtually hard up against the transformer secondary 
terminals, a safety gap set to fire at a higher voltage would be 
redundant. In future, I will place all transformers right up to the 
main gap and if necessary, place an RF grounded metal housing over 
all components at risk from secondary strikes. I am dead certain that 
the chokes and/or long lines running to the transformer secondary 
terminals have been a cause for considerable misery when it comes to 
NST longevity. The key is energy storage between the main gap and the 
transformer terminals. I will be firing with a couple of 15kV 60mA 
transformers in a couple of weeks and expect no problems by adopting 
this srategy.


> From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
> Sent:  Saturday, May 30, 1998 3:09 PM
> To:  Tesla List
> Subject:  Re: chokes-new question
> Hi Tristan,
>         I put the resistors just before the gap in each leg.  These will
> swamp out the ringing of the bypass cap and the chokes.  I also believe that
> they help quenching by isolating the gap from the impedances in the charging
> circuit.
>         The resistors you mention should work ok.  Not sure what the values
> of the other components are in you system so hard to say for sure.
>         I have two papers on this subject at my website which may help in
> explaining this:
> "Design of a Neon Sign Transformer Protection Network for Tesla Coil Primary
> Circuit Applications"
> and
> "Testing of a RLC Neon Transformer Protection Network for Tesla Coil Primary
> Circuit Applications"
>         www.peakpeak-dot-com/~terryf/tesla/experiments.html
>         The last paper was rather negative on the RLC circuit but I use too
> small of an R for that test in retrospect.  
>         Note that I put the charging circuit across the primary cap in these
> tests as a worst case condition.  You always want the charging circuit
> across the gap in a real coil system.
> Regards,
>         Terry Fritz
> At 11:24 PM 5/29/98 -0500, you wrote:
> >
> >----------
> >From:  Mad Coiler [SMTP:tesla_coiler-at-hotmail-dot-com]
> >Sent:  Friday, May 29, 1998 5:58 PM
> >To:  tesla-at-pupman-dot-com
> >Subject:  Re: chokes-new question
> >
> >All of you using resistors with you lowpass circuit: where do you put 
> >the resistors? Say for example I have safety gap, capacitors accoss the 
> >gap and inductors off each terminal of the gap going to the TC primary 
> >wires. Were do the resistors come in? I have been running my TC with the 
> >bypass caps, and with the caps & chokes, but dont have any R yet.  I do 
> >have four 3k ohm 25W resistors, is 3k or 1.5K usable for this?
> >
> >Tristan Stewart
> >
> >
> >
> >