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Re: Secondary Question

Original poster: FutureT@xxxxxxx In a message dated 4/5/06 2:40:14 PM Eastern Daylight Time, tesla@xxxxxxxxxx writes: 



Original poster: "Rich" <rdjmgmt@xxxxxxxxxx>

I want to build my 2nd coil this year and I have a question on the
secondary diameter.
  Power will be 13Kv 150ma transformer , RQ spark gap, MMC of C/D caps at 30.
My secondary can be a 9" dia mailing tube and 20ga silver plated
stranded wire with thin insulation or
6" PVC with 24ga mag wire.
Any  pros or cons on the secondary

Rich




Rich,

Folks often speak of a 6" secondary, or 9" secondary, etc.
But I think the height of the coil is more important or at least as
important.  If the secondary coil is too short, it will break down,
and/or have to endure racing sparks.  In a case where I already
have a transformer, I use my spark length formula:

   spark length (inches) = 1.7sqrt input power (wallplug watts)

Based on the predicted spark length, I select a suitable toroid
size, secondary height, secondary diameter, wire size, and primary
size.  I decide if the coil will be running at 120 bps, or a higher
bps, whether it will use a sync rotary, async, static gap, etc, then
select a cap value.  I posted the full design procedure on this
list a few years ago.

Of course much depends on the room you have available for
running the coil.  Much also depends on the spark type or
the type of sparks you're looking to produce.
John