Re: I want 2-footers, and I want 'em now! (fwd)

He said his cap calculates to .0054 MFD (I think he also mentions it being
higher after modification, 8 nF). Which is a bit undersized, but should be
functional, right? Of course the calculated value and the real value may be
different, but it's not as high as .03.

Or did I miss something? :)


Tesla List wrote:

> Original Poster: "Dr. Resonance" <Dr.Resonance-at-next-wave-dot-net>
> Your main problem is that a 30 mA current source is not enough to rapidly
> re-charge a .03 MFD cap for the number of bks/second you need for efficient
> operation.   30 mA matches up to a .01 MFD cap really good, but for .03 MFD
> you need around 120-150 mA of current.   Start paralleling transformers.
> Regards,
> Dr. Resonance
> -----Original Message-----
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
> Date: Thursday, October 14, 1999 5:54 AM
> Subject: Re: I want 2-footers, and I want 'em now! (fwd)
> >Original Poster: Tesla List <mod1-at-pupman-dot-com>
> >
> >
> >
> >---------- Forwarded message ----------
> >Date: Wed, 13 Oct 1999 09:48:58 EDT
> >From: Bobbaust-at-aol-dot-com
> >To: tesla-at-pupman-dot-com
> >Subject: Re: I want 2-footers, and I want 'em now!
> >
> >Apologies for the long-winded text that follows, I figured the more detail
> I
> >gave, the better your advice will be.
> >
> >I'm a newbie.  I'm using a 15,000 V -at- 30 ma NST for my first TC and what I
> >have been reading here indicates with a good design I should get 2 foot
> >streamers.  I can''t seem to break the 6" barrier.
> >Heres' what I started with:
> >
> >The TC is loosely built around plans in the current Nuts&Volts, so I've
> >followed their schematic.
> >
> >Primary: 8 turns of 14 awg copper on a 9" diameter circle, spaced 1/2"
> apart
> >Secondary: 800 turns of 28 awg on a 3.5" diameter by 14" PVC form.  Coil is
> >11.3" long.
> >Capacitor: flat plate type just like in the article, 4 pieces of 10x10
> >aluminum flashing with .030 polystyrene separators (I had it laying around,
> I
> >think it's polystyrene - white, flexible, opaque, and dirt cheep).  The DOS
> >software I downloaded indicates this is .0054 uf.
> >RF coils: just like the article, 21 turns of 18 awg on 1.5" PVC pipe (which
> >is really closer to 2" dia), one coil in series with each secondary of the
> >Input xfmr: 15,000 volts at 30 ma NST
> >Regular spark gap with 1/4" cap nuts.
> >Toroid made from two 1 1/4" plumbing "J" traps, cut and soldered together -
> >very smooth
> >"Ground" rod from one side of primary to a point about 5" above center of
> >toroid.
> >
> >I sent the above info to Nick off-line and he suggested doubling primary
> >turns and quadrupling # of plates in the cap.  Here's what I did:
> >
> >I doubled the primary turns by halving the spacing (16 turns at 1/4"
> spacing)
> >and finally experienced "tuning" at 11 turns.  Now I have a feel for the
> >difference between resonance or not.
> >This gave me 5-6" streamers but still required a 3/8" gap, and I started
> >getting secondary-to-secondary strikes between points about an inch or two
> >apart on the coil.  I also saw the capacitor arcing between the connection
> >points and the opposite plates (sneaking through the gap between the
> >separators), even though there's a good 1" overlap on the separators.
> >
> >So, I took the cap apart and found I mis-measured the thickness, it's .047
> >not .030.  I siliconed between the separators near the terminals and added
> 4
> >more plates.  The DOS software I have indicates this should be 1.2nf per
> pair
> >of plates.  I assume that means 8.4 nf for a 8-plate cap (1.2 x 7).
> >
> >Now it tunes at 6.5 turns with a gap of 1/4" but I still can't get more
> than
> >6" streamers.  The cap no longer arcs, but I still get some sec-to-sec
> >strikes even after spraying with high-dielectric conformal coating.  Help!
> I
> >want 2-footers by Halloween.  I can build caps and/or wind a new secondary
> or
> >primary between now and then but I'm stuck with the NST I have.  I could
> >maybe build a more complex spark gap, but not enough time for a rotary or
> >anything fancy.
> >
> >I also have these questions:
> >1. The DOS software suggests 5.3 nf is perfect for my NST, but it seems
> like
> >you guys go by the "bigger is better" principal.  What's up?
> >2. I see a lot of talk of refrigeration tubing for primaries.  Why?  We're
> >only talking about low currents, right?  What's the advantage of refer
> tubing
> >over 14 awg wire?
> >3. I see discussion of primaries, secondaries, caps and spark gaps, but no
> >mention of RF coils like the Nuts&Volts article uses.  Should they be used
> or
> >are they just insignificant enough to not warrent discussion?
> >4. The N&V article did not mention any particular grounding other than
> >connecting the bottom of the secondary to the NST ground (which is
> connected
> >to electrical ground).  This is what I have.  Good?  Bad?  Ugly?
> >
> >I would love to see someone elses work, and a working TC, but it sounds
> like
> >you guys are scattered everywhere.  I'm in Atlanta.  Anybody close?
> >