Re: Help with TC

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Esondrmn-at-aol-dot-com>

In a message dated 1/11/02 1:18:18 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes: 


>
> Hi all, 
> I have several TCs that I have been working on for quite a while, and 
> it seems that I can never get arcs nearly as big as people have said 
> on webpages, on the list, etc. for the same input power. 
>
> Currently, I am running a coil with two 9k60 NSTs in parallel, a PE 
> homemade cap of 35 nF, 3/8 copper tubing for the primary, and 22 AWG 
> wire for the secondary on a 4" PVC form, about 28" tall.  The primary 
> is an inverted cone, about 30 degrees, and has about 10 turns (should 
> be more?). It seems like I can only get it to run somewhat well if the 
> primary is tapped all the way in at around 2 to 2 1/2 turns, and wont 
> run well anywhere else.  I don't have an output terminal, and I know 
> this would lower the operating frequency, and then I would have to tap 
> it out farther.  Also, do the wire lengths from the cap to the primary 
> make a huge difference? They are 10AWG, but are about 3 feet long 
> almost, as my cap is in 4" PVC, a rolled type, so the terminals are 
> fairly far away. I just bought 12 0.05uF -at- 10KVDC caps for a MMC. 
> Will this help a lot? I am using a RQSG, with 9 sections, and a fan to 
> quench the spark.  What else could be improved, or what more 
> information is needed? 
>
> Thanks for any help anyone can provide. 
>
> Sean Taylor 



Sean, 

Running some quick calculations on your coil - and making a couple of
assumptions (danger) - it appears that your primary capacitor is too large.  I
calculate that you need a .004 mfd cap to tune this coil when tapped at turn
10, with no topload.  And it should tune around turn 3 as is.  It would work
much better, more effecient, longer sparks if you could use the whole primary -
at least out to turn 9 or so.  I would definitely make a toroid for it.  Even
if you just go to a hobby/crafts store and get a 6 or 8" diameter by 1 or 2"
thick styrofoam ring and cover it with aluminum foil.  You need something to
get the resonant frequency down.   You are inputing 9,000 volts at 120 ma which
is about 1,000 kva.  That is a lot of power, not too much for a 4" coil
however.  With a decent toroid and in tune, this coil should produce easy two
to three foot sparks. 

The long wires to the primary cap are probably not hurting the performance
much.  It would be nice if they could be as short as possible.  Maybe run the
coil on a table with the capacitor underneath? 

Ed Sonderman