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Re: SSTC does 10 foot sparks
Original poster: "john cooper" <tesla-at-tesla-coil-dot-com>
Does this enigma basically boil down to timing issues (once we resolve the
vernacular)? And the difficulty in tuning/measuring same throughout the
system? I'm intentionally leaving out the other dozen(s) variables. Jeez,
what a can of worms, I only have two storage scopes, that's not enough. We
need an X prize for this one, where's Paul Allen when we need him? And all
3 or 4 left standing can applaud.
---------- Original Message ----------------------------------
From: "Tesla list" <tesla-at-pupman-dot-com>
Date: Wed, 23 Jun 2004 21:22:17 -0600
>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
>>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).
>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!