Comparing Sparklength Was: Getting the bugs out- a little help, please...

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

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi John,
(changed the subject since it's going off of David's original intent)

Spark length to the nth degree is guess work. I was simply stating data 
Richard supplied against what was previously suggested. Comparing true 
energy input for a particular spark (long or short) doesn't necessarily 
identify that all will follow suit. I'm not confident sparklength 
assessment will ever do better than curve fitting can predict (controlled 
or otherwise). Even recent discussions with topload surface fields and 
possibilities there will still rely on many assumptions about the spark 
formation and how the spark propagates the path to the point where 
ionization at the head of the spark can no longer maintain the field to 
continue. I think the work needs to be done, I'm just not confident that we 
will come to conclusions useful to sparklength predictions anytime soon. I 
hope I'm wrong about that.

For now, if a coiler asks me what length can I expect based on a design, I 
am fine with a ballpark range. John F's formula has worked well in the past 
as a rough guide. His data is based on his coils efficiency's and supply 
efficiency's, etc... That's ok. What I'm doing with Javatc is looking at a 
little more detail in regards to the sparklength. The formula hasn't really 
changed, it's just that more detail is being thrown into the power 
assumptions for that value to arrive at possibly a closer ballpark value 
which in my opinion will scale well with various coil parameters. It is 
still a ballpark number and is not meant to be exact. It is also a design 
value and not necessarily a value which has considered such items as power 
factor (this can be found "after the coil is built", not before). Gerry has 
some good suggestions which I believe will further help in this area, but I 
have yet to go to work on that (there was just too much going on with a 
couple other projects). It is next on the agenda for Javatc.

Take care,
Bart

Tesla list wrote:

>Original poster: "John H. Couture" <couturejh-at-mgte-dot-com>
>
>Bart, All -
>
>Why worry about a random spark length with a random energy input? Until
>coilers are able to identify the true energy input for a particular random
>extra long spark length the comparing of Tesla coils by their random sparks
>is purely guess work. At present all coilers spark length estimates will
>have to be taken with a grain of salt.
>
>  To make engineering sense a coiler would have to determine the true input
>energy or joules for a certain random spark (of a group) and that at present
>is impossible to measure or at least has never been done. Even the
>controlled spark and watts input would only do a fair job for comparing a
>classical TC with a magnifier.
>
>John Couture
>
>--------------------------------
>
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Wednesday, November 12, 2003 12:09 AM
>To: tesla-at-pupman-dot-com
>Subject: Re: Getting the bugs out- a little help, please...
>
>
>Original poster: Bart Anderson <classi6-at-classictesla-dot-com>
>
>My data shows 162" (13.5 ft) identified in a photograph as longest spark.
>Richard stated it was 10kva (volt/amps reading). He may have indeed hit 15
>foot sparks at some point, but I'm certain it was greater than 10kva and
>probably in the range John mentioned.
>
>Take care,
>Bart
>
>Tesla list wrote:
>
> >Original poster: "Chris the great" <downnessisgoingup-at-hotmail-dot-com>
> >I believe he only used 9kVA to get those 15 footers.....all in all it was
> >a very nice coil.
> >
> >
> >
> >
> >>From: "Tesla list" <tesla-at-pupman-dot-com>
> >>To: tesla-at-pupman-dot-com
> >>Subject: Re: Getting the bugs out- a little help, please... Date: Mon, 10
> >>Nov 2003 21:06:22 -0700
> >>
> >>Original poster: FutureT-at-aol-dot-com
> >>
> >>In a message dated 11/10/03 8:18:30 PM Eastern Standard Time,
> >>tesla-at-pupman-dot-com writes:
> >>
> >>David,
> >>
> >>Well Richard Hull used approximately that cap value for
> >>his Nemesis coil which used a 10kVA, 10kV piggie.
> >>He used 11 to 13kVA or so and got about 15 foot sparks.
> >>He ran at about 450 bps non-sync.  I agree that the phasing
> >>won't be too critical at your 480 bps.  I would think your
> >>piggie has the power to charge those caps pretty
> >>well at 480 bps.  You could certainly compare the performance
> >>at 240 bps and see what happens.
> >>
> >>John
> >>
> >>>There are a couple of problems that I encountered
> >>>though. First, my Wysock-built rotory gap is sync at
> >>>480 bps and w/ .0825 uFD primary capacitance, I'm
> >>>thinking that's a little too fast for the capacitor to ever
> >>>be able to fully charge before discharging across the
> >>>SG and that would definitely limit my sec. voltage gain.
> >>>I haven't built a Freau phase adjuster yet either as I'm
> >>>not sure that the phase angle would even be that big
> >>>of an issue at 480 bps. I'm thinking about removing
> >>>4 of the 8 rotory electrodes to go for 240 bps. Maybe
> >>>some of you you more mathematically inclined mem-
> >>>bers can tell me what the best bps rate range should
> >>>be for this coil. My power supply is a 10 kVA, 14400
> >>>volt PDT controlled through (2) paralleled 1256 variacs
> >>>(up to 280 volts -at- 56 amps) and ballasted w/ a seriesed
> >>>225 amp arc welder w/ the welding leads shorted. It just
> >>>seems that I ought to be able get brighter,longer, more
> >>>powerful sparks w/ my available power. Of course, like I
> >>>said, I just roughly tuned it in tonight.
> >>
>
>
>
>