Re: The Tabletop Tesla Coil Showdown - OFFICIAL RULES and WEBSITE

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 10/7/02 7:23:58 PM Eastern Daylight Time, tesla-at-pupman-dot-com
writes:


>
> John F. -
>
> Let the contestant use any rep rate he desires. Now that would be a real TC
> challenge. Low rep rates would give more spark only up to a certain point.
> When that point is reached the losses would start to be greater than the
> input and the spark length would remain the same or start to decrease in
> length. This happens often with coilers who add input watts to their coil
> but beyond a certain point the spark length remains the same length much to
> the chagrin of the coiler.



John C,

A very low rep rate coil simply stores energy for a long period
of time and releases it quickly.  Such a set up can give terrific
spark lengths for a given input power, but not for a given
instantaneous input power of course.  Losses are not much of
an issue here.  We're probably talking about different kinds of
systems.  In one setup which I called the "DC Disruptive Pulsed
Compound Storage Tesla Coil", I was able to get 56" sparks using
only 460 watts.  It gave about 4 spark trains per second, and the
spark did not appear to be continuous.


>
> A contest with these rules means that a coiler would have to build dozens of
> coils of different configurations and inputs to find the optimum Tesla coil
> that would have the greatest spark length percentage over your equation. My
> estimate would be that the winner of this type of contest would have a coil
> that has less than 1000 watts input. I base this on spark data from the
> List. For example many 1000 watt coils give sparks over 4.5 ft, 



Many coils that are claimed to be 1000 watt coils, actually draw
a lot more than 1000 watts.  Folks use a 1000 watt NST, and
therefore call it a 1000 watt coil.  But NST's can draw much more than
their rated input powers, esp if powered by a 140 V output variac.

but there

>
> are no coils under 10 KW input giving sparks over 14.2 ft. Larger coils are
> even less spark efficient. 



See my comment above....

Note that pole type transformers have an output

>
> capability of over 10 times their nameplate rating when shorted. This means
> that the watt input for a certain random spark length would have to be an
> instantaneous type wattage. This type of metering is never done for pole
> type or similar transformers.



The watt input for a pole type TC system tends to remain 
reasonably steady, although there can be surges especially
using async gaps.  It's not customary to try to gauge the exact
wattage at the time the spark occurs.  An average input wattage
is usually considered to be acceptable.  One can eliminate 
surging by using a sync gap.  Using a sync gap, the wattage
stays steady, from spark to spark.  This would satisfy your 
desire to equate spark length with input wattage.

John F.


>
> John Couture