# Re: SSTC does 10 foot sparks

```Original poster: "Steven Ward" <srward16-at-hotmail-dot-com>

John,

>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: SSTC does 10 foot sparks
>Date: Wed, 23 Jun 2004 11:21:47 -0600
>
>Original poster: "John Couture" <johncouture-at-bellsouth-dot-net>
>
>Steven -
>
>How you measure the TC input isn't important. This is a free country and you
>can do as you please, within reason. The point that matters is to understand
>what you are measuring. If you don't understand what you are measuring you

Well of course you cant.

For example, if you are
>rating
>your TC in power units (watts) it does not make engineering sense to say the
>efficiency is equal to anything.

I suppose but...

Efficiency refers to energy units
>not to
>power units.

Here is the issue.  The operation of the ISSTC is such that its quite
difficult to say just how much energy is in the tank circuit over the
period of the "burst".  You see, the tank cap is not so much a storage
device as it is in a normal spark gap coil where you charge the cap to a
known voltage (thus you know its energy in joules) and discharge this
energy into the primary coil.  With the ISSTC you are constantly adding
little bits of energy on every RF cycle...  So, it is in my opinion that a
reasonably accurate method of determining the "energy" for each "bang" or
"burst" is to simply take the input power in WATTs and divide by the number
of BPS (burst per second).  So for example, if i was using say 4000W
average input power with exactly 100 bps that would be 40j per burst.  I
would assume a similar spark output from a SGTC that had a 40j capacitor
and that was of great efficiency (efficiency merely being getting most of
that energy into the spark).

Can we agree on the above paragraph?

If so, lets make things worse ;).  Now say i go nuts and run my coil with
1000bps.  The input power (assuming 40j per burst) should be about 40kw.
Now at this power the arcs are going to be MUCH longer due to streamer
growth issues.  But now if i was to compare the first scenario (at 100bps)
vs. the second (1000bps) to be the same simply because the energy per burst
is equal, then there would be a very large discrepency here.  One coil
would be doing 10 foot sparks while the other could spit out some 30 feet
of plasma.

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.

I guess so, but i never thought of that method of comparing coils.

>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.

Im sure its been covered a dozen times, but could you briefly elaborate on
how the tested and rated "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.

Yeah, that sounds likely.  I like to hit a target distance several times
before i make a fuss about it.

>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

I suppose if you had the right tools thats possible... like a storage scope
with infinite recording time and a synched up video camera to see just what
happens when you get the lucky strike ;)

Only continuous sparking with fixed lengths made sense.

Hmmm, im not sure about that.  TCs are too random to be judged like that, i
think.

Steve

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
>
>-----------------------------------------------------
>
>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Tuesday, June 22, 2004 9:35 AM
>Subject: Re: SSTC does 10 foot sparks
>
>
> > Original poster: "Steven Ward" <srward16-at-hotmail-dot-com>
> >
> > Hmm,
> >
> > Good question, how do we measure the input/output power?  I dont know
> > myself and wasnt sure it really even mattered, aside from being reasonably
> > close and honest with my guesses.  Someone wanna seal up a TC in a big
> > styrofoam container and see how much heat we create? hehehe.  Seriously, i
> > cant myself afford such measuring equipment other than some cheap ammeters
> > and a small wattmeter (that is too little for this coil).  What i *can* do
> > is use previous knowledge gained from my first prototype and others work
>to
> > make good guesses at things like how much power im using and what
>efficiency.
> > The other thing i can rely on is simulation results from pspice.
> >
> > The way i see it is, i havent blown the 20A fuse yet and ive had several
> > long runs so far (telling me it likely isnt pulling more than 20A).
>Other
> > thing is that my coil slightly beats Freau's spark length formula... well
> > this makes perfect sense, no gap losses (and i will tell you, my power
> > components arent wasting much at all, they run cold to the touch).
> >
> > So i guess whats most important to me (and likely many others) is that you
> > can get 11 foot sparks (i hit 11'4" the other night) on a 20A 240V line
> > without popping breakers and without a pig.
> >
> > Steve
> >
> >
> > >From: "Tesla list" <tesla-at-pupman-dot-com>
> > >To: tesla-at-pupman-dot-com
> > >Subject: Re: SSTC does 10 foot sparks
> > >Date: Mon, 21 Jun 2004 08:03:02 -0600
> > >
> > >Original poster: "john cooper" <tesla-at-tesla-coil-dot-com>
> > >
> > >Very intersting stuff, how do we agree on a baseline or procedure for
> > >energy in/energy out measurements?  Or am I asking too much?  I'd be most
> > >interested in someone describing and identifying the
>equipment/measurement
> > >techinques necessary, then we can either follow those procedures or 'wave
> > >our dix in the air' claiming whatever.
> > >John
> > >
> > >---------- Original Message ----------------------------------
> > >From: "Tesla list" <tesla-at-pupman-dot-com>
> > >Date:  Sun, 20 Jun 2004 17:03:02 -0600
> >
> >
> >

```