RE: NST power test

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

Original poster: "John H. Couture by way of Terry Fritz <teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>


To All -

In the Richard Hull report mentioned below the author proved his point by
doing the tests and producing a graph. However, how many coilers mistakenly
assumed the graph shown was for a Tesla coil load? The graph was actually
only for a resistive load connected to a neon sign transformer (NST). It
should be noted that a Tesla coil load on a NST is primarily a capacitive
load, the TC primary capacitor. The spark gap is a controllable resistance
load.

Several years ago I made tests and graphs for combinations of resistors and
capacitors connected to NSTs. The results were very infomative and showed
why the length of the streamers could vary so greatly from TC to TC using
the same wattage input. It was basically a matter of power factor in the NST
secondary (not NST primary) circuit. Very few coilers are aware of this
condition. The power factor in the NST secondary circuit can be easily
changed by changing the resistance and capacitance in the tests.  In other
words the combination of resistor and capacitance load on the NST secondary
are the main variables that determines the streamer length for the Tesla
coil. Higher power factors in the NST secondary circuit (Tesla primary
circuit) mean longer streamers. This has nothing to do with resonant
charging.

In fact every coiler should make these tests and learn why tesla coil
operation is so difficult, probably impossible, to predict with calculators
and simulators. For example the tests show how the VA output of the Tesla
coil can be greater than the VA input. Conditions like this have a direct
effect on the streamer length. These tests are easy to do in the workshop
with a NST, resistors, capacitors and the proper instrumentation. To apply
this knowledge with a TC operating at high voltage is very difficult. The
coiler usually only sees a difference in the streamer length when tweaking
the coil not knowing exactly what is happening in the TC system.

Some day I hope to make a report with graphs of these tests. However,
coilers can do their own tests now and write their own report.

John Couture

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


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, January 14, 2003 3:01 PM
To: Jon Rosenstiel
Cc: tesla-at-pupman-dot-com
Subject: Re: NST power test


Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Jon,

Very nice report!!  I noted on the fusor list that Richard wanted it passed
on, so I will copy the Tesla list too.  Please give Richard our best!!  You
may also mention that the posting record here is only like 130 posts per
day, so far :o)))

Of course, if one were to depot the NST and remove the shunts, then maybe
it would have a much more stable output suitable for a power supply.

I am also going to do a resonant test in the next few days that may have
limited applications as a power supply too if the load is stable.  I am
hopping to study SLTR effects more to get far more power out than the NSTs
VA rating ;-))  Definitely bleeding edge stuff there, but I have some weak
transformers I can use for this nasty testing ;o))

Cheers,

          Terry


At 11:18 AM 1/11/2003 -0800, you wrote:
 >Hi Terry, thought I'd pass this along.
 >
 >Richard Hull performed an output voltage vs. output current test on a
couple
 >of NST's, and wrote it up in a nice report. He posted his report in the
 >"files" section of the fusor forum.
 >
 >You can find it here: http://www.fusor-dot-net/board/index.php?bn=fusor_files
 >
 >Regards,
 >Jon