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Re: A search for a better primary



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Bart,

Thankyou for your comments. I will explore a helical primary a little more when I start looking for the geometry I want to use on my next 12x60 coil. I will report on what I settle on and if anything striking shows up. I'm currently in the process of rerunning the simulations with 12 segments instead of 9 and the results so far are essentially the same.

BTW, I mispelled one of the links (actually I changed the name after I posted it) so here are the links for three parts of the experiment:

http://hot-streamer.com/temp/GerryReynolds/A_Search_for_a_Better_Primary1.pdf

http://hot-streamer.com/temp/GerryReynolds/A_Search_for_a_Better_Primary2.pdf

http://hot-streamer.com/temp/GerryReynolds/A_Search_for_a_Better_Primary3.pdf


Gerry R.



Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Gerry,

Glad you posted this. I've been real busy with "life" lately, so it's
been a little difficult to have some alone time to check out the latest
in your sim/testing results. I did have a chance tonight. Excellent stuff!

I thoroughly enjoyed reading your report and listening to your thoughts
regarding that data. The detuned systems and related stresses was a
gratification for myself. My own conceptual mindset of detuned systems
is unchanged and supported by your simulations regarding voltage
stresses along the secondary. It was a real pleasure to read your
thoughts regarding those stresses.

I and many others have mentioned in several past posts regarding high
coupling and/or a detuned system being the prime suspect for racing
arcs. I always felt that coupling was the "easy" adjustment everyone
clinged to. I think most coilers fell into that trap. The fact is,
tuning of L1 is highly important. Coupling "tuning" and "inductive"
tuning go hand in hand, regardless of the primary position and proximity.

You've shown that higher coupling can be achieved with a larger pri i.d.
because the secondary can then be lowered (a more even coupling to the
higher sections of the secondary). My old large 13" coil as well as my
current 8.5" coil both have the secondary's at least 1" below the
primary inner winding. The 13" coil allowed this due to the large inner
winding of the primary. The 8.5" coil has a relatively close proximity
(pri to sec) but is a very high turn coil. I believe if it were more in
the normal range (1000 to 1500), I probably wouldn't get away with 1"
below the inner turn primary on that particular coil.

The past couple years, I've stayed out of the debates regarding coupling
(you know, where is the right distance to set the primary based on the
this secondary). I kept hearing the reduced coupling is better, etc.. I
just got tired of listening to it (I know better).

I think if you were to take this particular modeling to an extreme, you
might find that Tesla's Colorado Springs coil with the large helical
with great distance between the pri and sec might show some very
interesting results in coupling. What you've done is with a particular
geometry (flat primary). But I'm sure you can realize with this data
that repositioning the geometry and proximity of the primary can result
in a more even voltage distribution, higher coupling, and higher output
than capable on the typical flat primary.

I'm not knocking flat primary's, heck, I use them myself for good
reason. I think there are better geometry's from a standpoint of
secondary voltage distribution and inductive tuning, but I also think
they are more difficult mechanically and on scale.

Excellent study there and much to think about.

Take care,
Bart

Tesla list wrote:

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi All,

I just finished part 3 of this exercise that makes an in depth comparison between an "existing" primary located 1 inch below the bottom turn of the secondary that has a 1 inch space from the 8 inch coil form and a "new" primary design that is located 1 inch above the bottom secondary turn but with a 3.5 inch clearance from the same coil form. The existing primary has demonstrated a tendency for racing arcs that prompted this search.

Part 2 showed a simulation method that not only seems to predict the high stress levels needed for racing arcs, but also predicts where they would breakout. The prediction agrees with observation. The simulation, as shown in part 3, also shows what happens when the TC is out of tune.

In part 3, it is shown that even though the new primary has a greater overall coupling, it also has less stress on the coil reducing the tendency for racing arcs, and also shows greater tolerance for mistuning. If this approach works out, this may be a way to avoid racing arcs and yet get higher coupling and higher topload voltage. This may also be a way to improve the energy rise time at the top load and facilitate better streamer formation. The following are the links to the most recent of each of 3 parts. Please read the papers and comment.

<http://hot-streamer.com/temp/GerryReynolds/In_Search_for_a_Better_Primary1.pdf>http://hot-streamer.com/temp/GerryReynolds/In_Search_for_a_Better_Primary1.pdf

http://hot-streamer.com/temp/GerryReynolds/A_Search_for_a_Better_Primary2.pdf

<http://hot-streamer.com/temp/GerryReynolds/A_Search_for_a_Better_Primary3.pdf>http://hot-streamer.com/temp/GerryReynolds/A_Search_for_a_Better_Primary3.pdf

Gerry R.