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Re: A search for a better primary
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.