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Re: Semi-Rotten Spark Length

Tesla List skrev:
> 
> Original Poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> 
>   Finn -
> 
>   I did not intend to "dismiss" spark performance. Only wanted to point out
> the limitations of using sparks for testing and rating Tesla coils. The
> controlled spark presents a constant load to the Tesla coil similar to the
> Prony brake presenting a constant load when testing an electric motor.
> Varying length sparks do not do this.
> 
>   John Couture

Yes, I think I get it: You want a _continous_ spark, one that doesn`t go
like this: streamers, long hit to ground rod, streamers, streamers, hit
to ground rod...etc. etc.
Now, as far as I recall from 1/2 year on this list, you are the only
person who insist on this Controlled spark, and it makes perfect sence
to me, that this would make direct comparison btwn coils more fair, and
thus usefull.
I have also found by my own experiments, that it makes a difference,
which kind of breakout point the spark is leaving the top terminal from.
And what kind of shape the grounded rod has at the receiving end.
The intent of my question was, therefore, to encourage you to step
forward with a proposal for a standard geometry of these emitting and
receiving points, which, if they became generally accepted, could become
standard equipment around the coiling community.
This way, one more obstacle to comparison would be overcome.
Anyway, I will make a proposal myself, to make basis for a discussion.

The emitting point for a controlled spark must be situated at the end of
a 3/8 " /10 mm copper pipe, and have a radius of 3/16 " / 5 mm. The rod
must be vertical, leave the toroid at the equator, and be of a length,
so thet the point of the emitting hemisphere is 6 " /150 mm from the
surface of the toroid.
The receiving electrode of the grounded rod must exibit equal
properties.

Please view in a fixed-width font such
              as Courier.




This could be made from a piece of copper strap, bent to follow the
radius of the toroid, with a weight at the one end, that rests on the
centerplate of the toroid, to avoid that the whole thing slips down, at
the other end a copper pipe is soldered, with a acorn nut at the end.


        ********         6" / 150 mm
     ***        ***  <---------------->
    *              *                   
 ++* <--Weight      +----------------++ <----- Brass acorn nut
 ++*                +----------------++
                       ^copper pipe^
Does this make sence ?


Cheers, Finn