Re: neon vs. potential transformer
Sent: Tuesday, July 15, 1997 9:46 AM
Subject: Re: neon vs. potential transformer
<< John -
> Your experiments with TC wattage vs spark length are very important
> because there is little of this type of research that has been done for
> Tesla coils. I hope you will continue with this work and let us know of
> progress. In the past thousands of Tesla coils have been incorrectly tested
> for wattage vs spark length because they were tested without considering
> energy in vs energy out.
Hi John C,
For my purposes, I don't worry too much about energy in vs. energy out.
Yes, that is a true engineering definition of efficiency, but I consider the
ordinary power in vs. spark length to be more useful for typical coilers.
I thought your experiment using the light bulbs was intriquing though.
> Don't forget when you are comparing different types of transformers and
> using efficiency and power vs spark length that the energy equation must be
> balanced. This means you must know the true wattage and time (energy) plus
> the controlled spark length (total energy output).
Yes, I agree, if we don't know our waveshapes, then we don't know our
input power if we use ordinary meters. The "Dave Sharpe" meter should
solve this problem. Again, I'm not concerned with my output power, only
my spark length. We have a different viewpoint on this part of the matter
since I'm more concerned with true input power vs. spark length, regardless
of the "true" efficiency. Suppose it turns out that the best way to build a
TC for longest sparks vs. input power is NOT the same way as to obtain
best efficiency of output vs. input. This would be quite acceptable to me.
I still don't see the importance of the energy in vs. energy out of a TC.
This type of efficiency may or may not translate into long sparks and I
suspect it may not.
> Note that different types of transformers produce different waveshapes
> when the secondary is shorted as in TC operation. That means the di/dt
> (quenching) varies and this has a great effect on the spark length. The
> power factor must also be taken into consideration for both the input and
> output. Dave Sharpe's meter looks like a good bet. There are other ways to
> make this test as I show in the TCC Guide.
I didn't really see any difference in quenching using the different
transformers, I don't really think it should make much difference
in the synchonous set up I'm using.
> Several years ago I made a graph showing TC wattage vs spark length based
> on empirical data that I had collected from my tests and from other
> Because this data was sporadic and from older coils my graph needs to be
> updated. It has, however, appeared to work good with new coils when the
> correct wattage and controlled spark length are used.
I think that wattage vs. spark length follows a simple direct square law,
I sent in another post on this subject. Controlled spark length is useful
perhaps for measuring true efficiency of the type you advocate, but I
prefer free air sparks for my "efficiency" measurements.
> Do I understand that your 15 KV 30 and 60 ma neons were rewired for Tesla
> work? Did you ever try to compare their quenching with standard neons and
> the potential transformer? What are the details of your TC secondary coil?
The neons are not modified or rewired. Quenching was the same. Secondary
coil is 6.5" dia, by 23" high wound with #28 formvar wire. I don't think the
wire hurts the performance since most of the losses are in the primary rather
than the secondary. I think that many coilers concern themselves entirely
too much with secondary resistance.
> What do you think of the more than one charge (increasing wattage) per
I think that this is unlikely since generally by the time a gap fires, most
of the energy from the previous firing is gone from the system.
My two cents worth, comments welcomed,
> John Couture