RE: 'true" spark length was Re: Desktop Bipolar Coil

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

Original poster: "John H. Couture by way of Terry Fritz <teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>


Steve -

The concept of the controlled spark is to have as much of a constant TC load
as possible rather than a random load when testing Tesla coils. I believe
that the best that can be done is to have a spark for each bang in the TC
system. This is easily calculated as

   Watts per bang = total input watts/BPS

The controlled spark would be a continuous horizontal spark from the
secondary terminal to a ground point. The distance would be found by
starting with a short spark length and then increasing the distance until a
point is reached where the spark does not occur at each bang. It is obvious
this makes more sense than using a random spark length when the input watts
is used. Note that the input watts are actually watt-seconds energy on a
continuous basis.

This test would no doubt be improved as coilers get ideas while using it.
The OLTC may be a problem but I think only trying this test procedure will
point out the problems. One problem arises immediately. I have found that
with this test the small coils are more efficient than large coils. This is
not correct and the reason is that the spark distance represents mainly the
voltage. The current (spark core) has to be considered in some other manner.
In other words one equation

    Overall efficiency = watts in/watts out
    Watts in = Volts x amps x cos(x)
    Watts out = K (spark inches x core factor)

K would be a variable to convert the spark and core values into watt
seconds. The core factor would be found using a graph which would be made
from test data for a typical TC systems of varying sizes. There is a lot
more needed.

John Couture

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-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, July 06, 2003 2:58 PM
To: tesla-at-pupman-dot-com
Subject: RE: 'true" spark length was Re: Desktop Bipolar Coil


Original poster: "Stephen Conner by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 11:40 05/07/03 -0600, you wrote:
 >Original poster: "John H. Couture by way of Terry Fritz
 ><teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
 >
 >
 >
 >Steve -
 >
 >As you are using controlled sparks I will be very interested in your tests.
 >How will you be measuring the watts input?

When I said controlled sparks I meant that I would be measuring the spark
between a breakout point and a grounded point, rather than just letting it
rip and trying to guesstimate how long the streamers are :) I'm not sure if
this is what is meant by controlled spark: Dr. Resonance described some
sort of dowels and nails arrangement, whereas if I understood correctly,
you meant a spark between a breakout point and a grounded point that are
close enough together that it connects on (almost) every break.

Originally I would have measured the watts input by measuring the DC link
voltage and bps, and assuming a constant charging efficiency. But I suppose
I could measure the link current too. The voltage and current stay very
stable on the OLTC so I should just be able to write the figures down and
multiply them together afterwards :)

Steve C.