Re: Sweet (and sour) spots, was 120bps vs 240bps tests
Increasing power and size in the electrical world normally does improve
overall efficiency. However, with Tesla coils this does not happen.
Increasing the power for a particular coil will actually decrease the
efficiency after a certain power level is reached. The reason for this is
because increasing the power beyond a certain level increases the secondary
voltage which in turn causes greater "losses per input watt" in the
secondary. This is the main reason why classical Tesla coils must be made
larger to accomodate larger powers.
The best way to rate Tesla coils is by using the "watts input per foot of
spark" method. It has been found that this rating varies from about 200
watts/ft spark for small coils to about 2000 watts/ft spark for large coils.
These two parameters are easily found for any coil. The spark length can be
a controlled spark (John Couture) or a maximum spark (John Freau). Either
method can be used but should be indicated.
The next step is to set up an overall efficiency vs watts/ft spark graph.
I have done this for controlled sparks (not inverse square law) and show the
graph in one of my books. The parameters are based on data (albeit limited)
from real world coils built and tested in the past by myself and other
coilers. This graph appears to be resonably accurate for controlled sparks.
It appears John Freau is in the process of making a similar graph for
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Sunday, June 06, 1999 5:56 PM
Subject: Re: Sweet (and sour) spots, was 120bps vs 240bps tests
>Original Poster: "rwall" <rwall-at-ix-dot-netcom-dot-com>
>> In these tests, I ran the TC at various power levels, and with two
>> different toroid sizes, to see how far the spark length would vary
>> from the square law predicted lengths. Spark length shortfalls from
>> predicted lengths might mean that the coil is becoming inefficient in
>> some cases, or in other cases it could mean that the square law
>> is not precise for predicting TC spark lengths as the power input
>Again, excellent experimental work. As conducted, spark efficiency appears
>to fall off as predicted by the inverse square law with decrementing power
>input. This same data may also be analysed and concluded that spark
>efficiency appears to improve as predicted by the inverse square law with
>increasing power input. This raises the question of whether increasing
>power really improves system efficiency or do our TC systems really not
>follow the inverse square rule?