RE: Primary coil configuration

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Hajdrowski, Leo T." <leo.hajdrowski@xxxxxxx>

Hello,

I have a quick question regarding primary coils.

How close (or far away) to the secondary should the closest winding of a
flat spiral primary be if the primary is made of 3/8" copper tubing?
Note: the secondary is 10 1/2" in diameter.

Also, is it OK to have a plexiglass tube over the secondary at the
primary height level to help prevent arcing?

Thanks.

Leo

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Friday, April 21, 2006 12:15 AM
To: tesla@xxxxxxxxxx
Subject: Re: Primary coil configuration

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>



Solenoidal primaries will produce overcoupling if used in any coil dia.
above the 4 inch size.  Flat spirals work best for efficient energy
transfer without "racing sparks".

Racing sparks are always caused by overcoupling or too small toroid size
(causes coil to produce standing waves because certain harmonic
frequencies and complex frequency interactions are not being surpressed
enough).  Use a toroid that is at least 2 x sec coil dia
(3 or 4 x for max performance systems) and you will not have racing
sparks assuming your sec coil is properly elevated above the pri.  We
have used motor driven adjusters to dynamically tune 4", 6", 10", 12",
18" 24", and 36" dia. sec coils while they are running to determine
optimal sec coil heights above the horizontal plane of the primary to
produce a maximum length secondary spark.  4 inch systems respond well
approx 1.125 to 1.25 inches above the pri top turn (flat
spiral) or even with base if using a 15-20 degree cone.  This will
produce the optimum spark length when driven with a 60 mA xmfr.

Someone advocated adjustment until racing sparks occur and then backing
off. This is horrible engineering.  Once a spark punctures a solid
insulation it does not "cure" or repair itself.  Once the damage is done
it is permanent unless the coil is rewound.  You can back off the
coupling to reduce sparkover, but then you always have a weakest link in
your coil system. Properly sealing the sec coil and then not puncturing
it will produce a long lasting coil.

Dr. Resonance



>If you place the primary off center in a half wave coil you will find
>that the performance drops quickly. ( and If you tilt the primary the
>performance drops like a rock)
>
>Solenoidal primaries work just fine. I like them better then pancake
>primaries they are easier to make and tune. You can wrap tube around a
>drum and get a nice copper spring. Compress the spring and the
>inductance goes up. Stretch the spring and inductance goes down.
>
>You can make spacers and spiral them into place or weave nylon rope
>between the winds and epoxy saturate the rope for a rigid structure.
>
>Sincerely: Jared Dwarshuis