Re: Collected coil data (fwd)
---------- Forwarded message ----------
Date: Wed, 29 Jul 1998 17:41:05 -0600
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Collected coil data (fwd)
At 09:02 PM 7/28/98 -0600, you wrote:
>From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: Collected coil data (fwd)
> Terry -
> Thank you for doing the work of collecting the coil data and posting the
>info on the List. This will be a big help for the coilers developing TC
>computer programs. However, why are you using joules for primary energy input?
The energy stored in the primary capacitor represents the total
energy available to the system for a given firing cycle. It is
fundamentally important for coil analysis.
> This could be a big mistake in rating Tesla coils because it leaves too
>much room for errors in judgement. This could result in wild estimates of
>the true nature of the TC input for a certain output spark length.
It is not a rating. Obviously firing rate, quenching, adjusting the
coupling, etc. are also critical to a coil's operation. This is just a
fundamental factor that is considered along with these others.
> The joules rating you are using are watt seconds for a particular spark
>length. The spark lengths are varying with a continuous operating coil and
>the watt seconds are varying. With a continuous operating TC the watt
>seconds for a particular spark cannot be measured, only estimated.
The data was not intended to correlate any number to any other. It was
simply meant to supply information that we generally don't have handy on a
number of different coils situations. My VI antennas can measure the output
energy of a particular spark over time.
> It makes more sense to use measured RMS ratings for both input and output
>instead of estimated instantaneous ratings. I don't think you would want the
>Electric Utility basing your electric bill on estimated instantanneous
> John Couture
It wasn't my intention to suggest that the joules represented anything more
than the energy stored in the primary capacitor just before the system
fires. I personally like to know this number as a reference when
considering were all the energy is being expended in the system. When I
find that the secondary is wasting 0.2 joules to heat, I like to know if
that is 0.2 joules out of 1.5 joules of initial energy or 0.2 joules out of
20. In other words, I can judge how serious a given energy loss is.
The problem with RMS ratings is that they are very difficult to measure for
most people. The dynamic voltage, current, and phase of the AC input to an
operating coil cannot be measured with typical equipment (although, with the
right equipment, it can be measured extremely accurately very easily). As
far as I know, my antenna probes are the only instruments that can even
attempt to measure secondary output RMS power and the data still needs to be
feed to a computer for analysis. The initial energy on the primary cap,
however, is one solid energy level that is not difficult to find and is
fundamental to the system.
We all have our "pet" measurements we like to use. These range from
sophisticated arc power measurements using thousands of dollars worth of
equipment to just noticing how much the lights dim. Each method works for
each person's own situation. Since most of us build coils for fun, perhaps
the best measurement for a coil would be the fun divided by frustration it
provides the owner.