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Re: New System, was "Real Data--
Tesla List wrote:
>
> > Subject: Re: Real data from real experiments.
>
> >From ccurran-at-execpc-dot-comFri Nov 15 22:55:30 1996
> Date: Fri, 15 Nov 1996 19:06:04 -0600
> From: Chuck Curran <ccurran-at-execpc-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: New System, was "Real Data--
>
> 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
Chuck,
I'm definately going to have to see this coil when you're done!!
Your coil parameters look to be in the ballpark! By using a 0.1uF 20 KV
cap, you'll have twice the energy/bang than if you used CP's next
smaller size cap. Since CP charges $325 for their 0.05 uF and $450 for
their 0.1 uF, the latter will double your "energy per bang" for only
$125 more. As long as you can deliver enough input current to your pig
to rapidly recharge the cap, you should get spectacular performance.
Some other considerations:
1. With a 60" x 12" toroid, you'll probably see around 50 pF of
effective capacitance after taking into account the "shading" from the
top of the secondary coil. Also, the actual number of secondary turns
will probably be somewhat less, since its very hard to maintain 100%
perfectly close winding. I'd multiply the predicted number of turns by
about 97% or so to compensate for this effect. The combined impact of
these two factors increases the loaded resonant frequency of your
secondary - my estimate is about 60-66 kHz. However, once you really
start cooking, the ion cloud around the toroid should drop it down
somewhat. I'd size the primary for 60 kHz nominal so that you get about
70 uH at a point about 2-3 turns in from the maximum number of turns.
2. Your primary current will be much larger. Assume you've set your
system's gaps to fire in the range of 15 KV to 19 KV. Your primary
energy/bang will be 11 - 18 Joules, and your peak primary current will
be in the 575 - 725 Amp range. This may require you to beef up the
design of your rotary (i.e., larger electrodes and forced-air cooling to
remove the additional heat).
3. You won't need 15 turns on your primary. If you start the inner turn
at a diameter 4" larger than your secondary, and use 5/8" or 3/4" copper
tubing, a 11-turn coil should take you down to about 47 kHz, and would
let you run at 60 kHz at about turn 8.5. A 15-turn coil would permit you
to run with a 0.05uF cap, but would offer _no_ other benefit. Unused
outside turns create unnecessarily high/hazardous voltages at the
outermost primary turns from autotransformer action. Use only half the
coil and you'll get 2X voltage multiplication at the outer turn.
Also, if you mount the primary coil assembly on a separate piece of
plywood with a cutout in the center, you can adjust the coupling fairly
easily (certainly easier than trying to raise/lower the secondary -
you'll have almost 36 pounds of copper alone on the secondary).
4. You probably have to beef up your RF grounding system. The current
peaks coming out of the secondary's base will be significantly higher
than before - over 20 Amps. This is probably at least twice what you
were running before...
5. The 12" aluminum ducting should work like gangbusters! You can always
make your system break out wherever you want it too. Its MUCH harder to
prevent it from breaking out too early - larger ROC is the easiest way.
Where'd you get yours from?
Hope the above helps!
Safe coilin' to ya, Chuck!
-- Bert --