New System, was "Real Data--

To: tesla-at-pupman-dot-com
Subject: New System, was "Real Data--
From: Chuck Curran <ccurran-at-execpc-dot-com>
Date: Fri, 15 Nov 1996 19:06:04 -0600
Tesla List wrote:
> 
> >From Esondrmn-at-aol-dot-comThu Nov 14 22:02:26 1996
> Date: Thu, 14 Nov 1996 13:32:59 -0500
> From: Esondrmn-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: Real data from real experiments.
> 
> In a message dated 96-11-13 01:44:26 EST, you write:
> 
> <<
>  Richard/Malcom:
>         I hope I am not repeating a question already asked,but here goes.  Is
>  there a way you could suggest to select the best size cap for a given
>  set of coil parameters?
>  I have that new PVC form I mentioned and I am ready to start the primary
>  component selection and construction.  The primary is a piece of 15 1/4"
>  O.D. PVC and the coil will be 50" of #15 wire, or 831 turns. Primary was
>  going to be 5/8" thin wall copper tube.  I was considering a .1 mfd cap,
>  but I really do not have a feel for what exactly the primary L/C ratio
>  should be for optimum spark.  Your comments woud be appreciated.  Thanks
> 
>  Chuck Curran
>   >>
> 
> Chuck,
> 
> How large will the primary be?  I would recommend 14 to 15 turns.  Best bet
> for the primary is large L and low C.  Calculate the resonate frequency of
> the secondary with a reasonable sized toroid like at least 30" to 40"
> diameter.  Calculate the primary inductance.  Now calculate the capacitor
> required to match the secondary frequency with the primary tapped at say 12
> turns.  What size transformer will you be using?
> 
> I assume this if for a classic two coil system, correct?
> 
> Ed Sonderman

Hi Ed:
	Right now I am trying to sort through several alternatives associated
with my winter project.  Yes, it is a two coil system and I have a 10
KVA 14,400 VAC pole pig, welder ballast and Superior 1256D variable
transformer in the supply.  Last night I decided to change the secondary
to a 56" length with the 15.25" form diameter in order to get a bit
lower in frequency.  This results in a resonance of about 106 Khz
without a toroid.  My curiosity at this point centers about picking the
optimum capacitor size, with maximum spark being the goal.  I originally
thought a .1 mfd cap would be about in the correct range, but alot
depends on how far the secondary resonance will drop with a proper
toroid, if an ideal L/C ratio is a target.  I'm still not clear on what
the proper L/C ratio might be.  My 8" diameter by 28" long coil had a
221 Khz resonance and with the 48" toroid it dropped to a measured 94
Khz.  If I could expect the 106 Khz resonance of the new secondary to
drop to around 50-55 Khz with a big toroid,  I would have a primary
needing about 100 uh with the .1 mfd cap.  O.K., I guess I could just
slap a random choice cap size in there and hope for the best, but
another option makes more sense to me.  That option is, we have a
tremendous amount of experience in this group and I sure don't mind
listening for a few weeks and filtering out the stuff that will help me
get a notch closer to the best I can personally do (The real story is, I
sure don't want to spend $450-$600 on a cap that isn't quite right!). 
My last primary had 15 turns so I have no problem with a similar design
here.  I will use 5/8" thin wall copper refrigeration tube, if they make
it in that size!  Haven't checked yet.

	I am planning on using the 12" diameter flexible aluminum air duct for
the toroid perimeter.  I used the same type of stuff but in 6" or 8" on
the other coil and was happy with the results.  I figure on a 60"
diameter for this one.  Yea, I guess I'll need lots of power to get it
to break out.  I have room for a few more breakers downstairs and the
next one will be a 100 amp line out to the Tesla area, or that spot my
wife calls the drive way.  Silly, she thinks she will be able to use the
garage next year!  
	I got a couple of parts made today for my winding system for the
secondary.  I should have the PVC form mounted up and getting close to
winding this next week.  I am getting a gear reduction drive unit
coupled to a shaft and support system to hold the form while winding and
then I'll coat it with the Behr Super Build 50 polyurethane varnish--I
really love that stuff!  I will take photo's so that when it's 10 below
zero here I can have something to look at and wait for spring.  As
always, I appreciate any ideas and comments.  Thanks in advance!

Chuck Curran 
Cedarburg, WI