Re: SSTC does 10 foot sparks

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

Original poster: "John Couture" <johncouture-at-bellsouth-dot-net> 

Sean -

You are right. I really messed up that post. Not enough checking of what I
thought I said.

What of the post I sent to Matt?

John Couture

----------------------------------------



----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, June 23, 2004 10:22 PM
Subject: Re: SSTC does 10 foot sparks


 > Original poster: Sean Taylor <sstaylor-at-uiuc.edu>
 >
 > I've gotta reply to this . . .
 >
 > On Wed, 23 Jun 2004 11:21:47 -0600, Tesla list <tesla-at-pupman-dot-com> wrote:
 > >if you are rating
 > >your TC in power units (watts) it does not make engineering sense to say
 > >the efficiency is equal to anything. Efficiency refers to energy units
not to
 > >power units.  However, if you are rating your TC in power units it does
 > >make sense to say it has a power gain of a certain amount. You can then
 > >use this number to compare with other TC's.
 >
 > Giving an efficiency in power makes perfect sense.  Most devices are rated
 > in this way.  A motor has a certain electrical power in, and a certain
 > mechanical power output.  The efficiency is defined as Mechanical power
out
 > / electrical power in.  A heater, lightbulb, and many other devices can be
 > given an efficiency rating the same way!  What doesn't make sense is to
say
 > we have a motor which has a certain power output, and then try to
calculate
 > the energy output by lifting a mass, or some other means and at the same
 > time monitoring the input power and integrating - much more of a pain, and
 > will arrive at (approximately, due to measurement error) the same result.
 >
 > >The above, of course, does not solve the problem of how to properly test
and
 > >rate a Tesla coil when using spark length as the TC output. In the past
only
 > >a few coilers could rate and test their coils properly. This resulted in
 > >shorter sparks. However, everyone was more impressed by that random extra
 > >long spark so any tests that gave shorter sparks were not popular.
 > >The problem was the true input energy that actually created that special
 > >extra long spark could not be determined so true TC comparisons could not
be
 > >made. Only continuous sparking with fixed lengths made sense. But it does
 > >not appear that we will ever get away from that mysterious random extra
long
 > >spark test with an unknown input ( except maybe for one shot tests).
 > >
 > >John Couture
 >
 >
 > What is rating a coil "properly"?  The only way to have a relatively
 > constant bang energy is to use a triggered type of gap (rotary, etc.) and
 > then how do you calculate the energy in and out?  What is rated "properly"
 > such that the coil ran with a "constant" length spark?  As line voltage
 > fluctuates, and environmental conditions change, so will the spark length
 > on the output, and there is no "rating" that will change that.  I am
 > interested to know what you are suggesting changing on a coil that would
 > "rate it properly".  Do you have any documented proof that this was done,
 > or what was changed?
 >
 > In your other post regarding the energy in a single spark, I'm sorry to
 > say, but that is complete bull.  There are several problems with the logic
 > - 1) How was the breakrate known to be 120?  2) The system definitely
isn't
 > lossless!!!  3) Wattmeters don't give you Watts/sec, just watts, that's
 > it!  4) There is streamer growth over successive bangs, so unless you know
 > the voltage you charged the tank gap too, are running ina single shot type
 > of set up, and know the exact losses of the system, there is no way to
know
 > the energy in the 8.25" arc!!  As you state, there IS a lot more, but the
 > problem is this isn't even a start towards really figuring anything
 > out.  The energy in an arc is not solely determined by its length either,
 > as you can have different amounts of current flowing through the arc, and
 > thus very different amounts of energy.
 >
 > I'm not trying to insult you, John, but there are several very fundamental
 > mistakes in the calculations you have done (specifically in calculating
 > voltage, current, etc. in the secondary), and you should really try to
read
 > up on how the quantities interact/relate.  One definite flaw was
"Secondary
 > current = joules/voltage".  I'm not going to use more time/bandwidth of
the
 > list, and I'm sure several people are getting tired of this discussion, so
 > I'll leave this discussion with this:  True power ratings are a very good
 > estimator of how much power is getting to the actual coil for the same
 > type, ie SGTC, SSTC, etc.  To compare Steve's ISSTC to a SGTC with the
same
 > power input that gets half of the spark length tells me that either a) The
 > losses in the ISSTC are much lower, or b) the output waveform of ISSTC is
 > such that it is able to facilitate streamer growth to a much greater
extent
 > than the SGTC, and for the purposes of the hobby, I would consider either
 > scenario to be much more efficient than the SGTC!
 >
 > Sean Taylor
 > Urbana, IL
 >
 >
 >
 >