Re: Request for coil data. (fwd)
---------- Forwarded message ----------
Date: Tue, 21 Jul 1998 22:35:48 -0500
From: "Barton B. Anderson" <mopar-at-uswest-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Request for coil data. (fwd)
Terry; my specs intersperced below.
Tesla List wrote:
> ---------- Forwarded message ----------
> Date: Wed, 15 Jul 1998 00:18:04 -0600
> From: terryf-at-verinet-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Request for coil data.
> Hi All,
> I would like to request some information to help see what kinds of coils
> produce what kinds of arcs and how that may relate to the thread about
> output loading and such. I suspect, in general, coils with a high
> SQRT(Ls/Cs) ratio produce longer cooler sparks while coils with a low ratio
> produce short but hot arcs. With some basic data from a number of coils we
> may be able to find a trend which will help in the design of new coils.
> Anyone who would like to supply the following information can E-mail it to
> me at:
> This will keep this list from getting clogged up with a bunch of E-mails.
> In a few days I will look at the data and report back to this list if I see
> any great trends or whatever. I will also compile the results and pass them
> all along for others to see. The data I think is important is as follows:
> (Please include the measurement units such as inches, cm, picofarads, etc.)
> Secondary Inductance
> Length and diameter of secondary
Length = 34.2", Dia = 12.5"
> Wire size and number of turns
18 awg polythermaleze magnet wire783 turns
> Secondary Capacitance (this is combined terminal and self capacitance)
50.6uH (toroid = 30.2pF, secondary = 18.4pF)
> Coupling Coefficient from primary to secondary if you know it
Not sure. Please email if the parameters can define.
> Primary Inductance
> Primary Capacitance
.06uF (tank cap? I assume. Don't have Primary inductors capacitance)
> Spark Gap Type
RSG, 1800rmp sync gap. Alluminum disk with 8 copper electrodes where 2 of 8
eletrodes lines up for discharge. G6 fiberglass composite cover of main alluminum
disk. Not the greatest, but is doing the job until my all G10 fiberglass disk is
> Type of Top Terminal (size, smoothness and construction)
Size = 6.6" x 29.5". Plastic water evacuation tubing "sewn" together to form a
circle. Double sided tape wrapped around and then alluminum foil ("reynolds wrap"),
then copper tape (sticky back) wrapped on top of alluminum. Toroid has wavy vertical
protrusions due to tubing form. Have always noticed in pictures that disharges
disharge at "exactly the same points" on the toroid. Fully smooth toroid is
> Primary Voltage
14.4kv x 2.5 = 36kv p-p
> Power Source (neon, pig, etc.)
10kva, 14.4kv pole pig. Remanufactured by Soloman Corporation.
> Output Arc Distance
So far 60". Have rarely run at full power due to "home difficiency's". Neighbors and
garage ceiling distance limites full power. At one point I did run full power and
acheived 84" discharge, but only ran this once (shorted a secondary wire in th
process. Repaired by removing the shorted two wires and soldering together - quick,
easy, worked great repair).
> Output Arc "Character" (White hot, thin purple, single streamer, many
Mostly thin purple continuously, safety gap firing periodically with a major blast!
Periodicaly get white hot arcs which are long and protrude far beyond "purple haze".
The last time I ran the coil in the garage, I was get frequent white hot arcs to the
RSG cabinet framing. (RSG is completely gournd screened). I moved it further away
from coil and got periodic "long" arcs to misc surroundings (i.e, my sons bike,
etc...) about 6 foot disharge on this run.
BTW, my runs are very short. Never more than 30 seconds continuous. This should also
be a factor in your inquiries.
> Any other information you feel is important...
Terry, there is so much that is important. My coil is a first coil. This is
important! I am not a "master coil builder", although I am proud of my setup, I
have many thoughts of improvement. Probably all coilers feel this way. My caps are
professional built 80kv .02uF( 3 ea). They were offerred to me at zero cost due to
my contacts at CSI and the number of caps my company purchases from CSI in CA. The
rest of the components were hand built.
BTW, Primary is flat spiral of 13 turns tuned at about #9. Bottom secondary winding
is about 1/2" about primary ( no racing secondary arcs or damage since moving
secondary up - and no diminish in spark length - actually, an increase by a few
inches). In the works is an Ed Sonderman top load to increse Ctop by more than
double. Should be fun!
> Please say if you are unsure of a parameter so I won't spend a bunch of time
> trying to resolve a number that may be inaccurate. If you don't know some
> information, pass along what you have. I can usually guess when needed. I
> am interested in only the standard spark gap type coils at this time.
Again, coupling I am unsure of mainly because I am unsure of a calculation which
takes into account an aircore transformer in the realm of TC's.
> I am especially interested at coils at the extremes. Those that have
> unusually long arcs and are great performers and also those that have
> unusually short arcs. If you have a coil that should perform well but
> doesn't please pass along the information on that coil as well. It is just
> as important to look at poor performing coils and those that show unusual
> performance characteristics. Of special interest would be coils that give
> great (or terrible sparks) in comparison to other coils for the same input
> power. Perhaps we can also determine why some coils have problems that
> really should work.
I think my coil is capable of twice the distance of discharge. I am not sure that I
have it adequately tuned. I am very sure that my coil can do much better with a
smooth and larger Ctop (including diameter) toroid. Also, a fully G10 type RSG is in
> If the Ls/Cs ratio is affecting the performance of our coils, perhaps this
> information can help us find the best values to use.
> Thanks very much for any help anyone may provide. Hopefully, I can sort
> through the responses ASAP. I will pass along all the data in some
> reasonable form so that it is available to everyone.
> Thanks very much.
> Send info to:
> Late Breaking News!!!
> I wrote this up at work. I thought it was so neat, I left work a
> little early to go home and send it out right away. Unfortunately, on the
> way home, I planted the front end of my car into the rear end of the car in
> from of me. My Cadillac will need the usual minor (but not cheap) bolt-on
> "collision-expendable" plastic parts replaced. The little Sunbird I hit
> will now be playing in the accordion section of the local junkyard.
> Fortunately, no injuries or anything bad except to my wallet. :-((( Court
> date, August 24...... Hey, is this dedication or what!!
> BTW: I recently replaced my old 500cid 7000 lb caddy with a newer 4500 lb
> version..... it still kicks butt!! ;-))
> Terry Fritz