Re: Streamer loading effect

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

Original poster: "D.C. Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>


I've also posted an update to John's original equation.  I think Terry has
it in the archives.  It does involve a "k" factor multiplier which depends
on your sec. coil dia.

This equation comes from over 20 years of coil data with different sec. dia
measurements.

Best regards,

Dr. Resonance




----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, August 11, 2002 4:53 PM
Subject: Re: Streamer loading effect


> Original poster: "Barton B. Anderson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>
>
> Hi Steve,
>
> Congrats on the detuning success! Some comments below:
>
> Tesla list wrote:
>
> > Original poster: "Steven Ward by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
> <srward16-at-hotmail-dot-com>
> >
> > Now the arcs ar so big that its really not noticeable, but what do i
> care, the arcs are
> > great!
> >
> > I have a question about efficiency with my coil.  On the classic tesla
java
> > TC calculator, they say my coil with a rotary gap, could produce a 6
foot
> > arc.
>
> The equation used is sqrt(input watts) * 1.7. This is John Freau's
original
> spark length emprical
> equation. JavaTC uses this same original equation at this time. John has
> updated the formula a few
> times to reflect transformer types, etc. I've chosen to keep the original
> equation. My reasoning is
> simple. It's a spark length empirical formula and at best a close
> guestimate which is based on input
> VA measurements and spark length. I wouldn't think to hard on it, your
coil
> is doing fine. A rotary
> may help or may not. It's difficult to identify how well the RQ gap is
> performing without a direct
> comparison. Gaps definately play a role in spark length. Well, anything
> does that allows energy
> transfer at decreased losses. I've built several RSG's (some bad, some
> good). Performance is in the
> workmanship, material, and operation of the RSG, as with anything.
>
> > This makes me wonder about how helpful rotary gaps really are.  Im
> > using a somewhat undersized RQ gap, and getting close to the
theoretical,
> > optimal output for my coil.  Am i missing something here, or is my coil
> > quite efficient for the spark gap that i have?  Or would perhaps a RSG
boost
> > my output beyond 6 feet?
>
> The spark length in JavaTC is thrown into the RSG design area "only"
> because there was nowhere else
> to logically put it at the time. The formula does not differentiate
between
> gap types (see John's
> equation). It's based completely on wall plug input watts for what John
> acheived at the time the
> original equation was derived.
>
> >  This 6 foot figure that the calculator gave me is
> > somewhat puzzling.  If John F. can get 42" (or 44" now) from a 12/30,
why on
> > earth would a figure for 6 feet on a 1800w coil make sense for high
> > efficiency?  I know larger coils loose efficiency per power.  Oh well, i
> > should just be happy with what i have, and what i have is good enough
for me
> > :)
>
> The last report I saw from John was a comparison of different NST's.
There,
> John's TT-42 coil
> acheived 38" using a Jefferson 12/30 NST running 140V input (uses variac
to
> step up input voltage).
> On his website, John mentions 42" using a "rubust" NST. The term "robust"
> indicates the NST is
> pulling more than it's rated VA rating. For 42", he was probably
delivering
> 620W or so to the coil.
>
> If you do a search in the List Archives, search for "TT-32 TC results and
> specs". This was a post
> from John and may help. It includes the TT-42 coil as well.
>
> If we were to model the 38" case in JavaTC, we would enter 140 in the
> "Applied Vin" input box. This
> changes the output watts to the coil to 490W and is identified as
effective
> output power. The spark
> length then shows 37.6" and very close to 38". It may be helpful to
measure
> input volts and amps to
> verify your actual watts if you haven't done this already.
>
> On a side note, I'm nearing completion on the next version of JavaTC
> (v9.2). This new version will
> include a static gap section (which can also be used for safety gap
> settings) and will help identify
> gap setting vs. arc voltage, bps, RQ gaps, etc.. The transformer section
> now includes ballast
> current input for those who externally limit current. Also new are help
> files instead of the simple
> text box notes used currently. The help files provide more detailed
> explanation and graphical
> representation of measurement. I'll post to the list once I complete a few
> more details.
>
> Take care,
> Bart
>
>
>
>
>
>