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Re: Capabilities of Small Thin Wire Secondaries (fwd)



---------- Forwarded message ----------
Date: Tue, 28 Jul 1998 16:25:46 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Capabilities of Small Thin Wire Secondaries (fwd)

Hi John (Freau),

> Date: Mon, 27 Jul 1998 17:57:23 EDT
> From: FutureT-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Capabilities of Small Thin Wire Secondaries
> 
> All,
> 
> The purpose of these tests was to explore the capabilities and
> limitations of small thin wire secondary coils. 
> 
> Initial specs:   Pri, # 12 stranded pvc ins. wire close wound flat
> pancake, 3.5" inside dia.  tapped at 18 to 21 turns as needed, about
> 87uH.  Sec, 3" by 9" styrene form tight wound with 1200 turns # 34 
> isomid enamel wire, 30mH.  Toroids, 1.5" by 4.5" placed on top of
> sec, with a 3" by 12.5" alum. dryer duct toroid on top of the small
> toroid, with metal spacer in between.  Static gap is (24) 1/2" by 2"
> copper pipes glued to a board, spaced 8.5 mils similar to Terry F's 
> design.  Powered by one or two 9kV 30ma NST's.  Cap is .007uF 
> polypropylene.  No safety gaps, chokes, resistors, etc.   
> 
> Test 1:  For this test, I used an old static gap having 4 series gaps,
> each spaced about 1.2mm.  This gap performed poorly and quenched
> on the second notch at k = .1 (sec is 1.25" above the pri.).  Spark
> length was 21".  Racing sparks appeared on sec at tighter k values. 
> One NST was used for this test.  Sparks are blue and do not appear
> purplish despite the thin wire.
> 
> Test 2:  Cap was increased to .014uF and coil re-tuned, but racing
> sparks made it impossible to continue.  With sec raised 2" above
> primary, output sparks were weak.  .014uF may have been a little
> too much capacitance for the NST also.
> 
> Test 3:  Back to .007uF using the new Terry F.- type gap, (used
> 14 gaps).  This gap quenched much much better than the previous
> 4 section gap, and gave 1st notch quenching at all times even with
> tightest coupling at k = .2 (sec lowered all the way).  Sparks are
> still 21" long, but now multiple streamers are formed.  Streamers
> occasionally strike the primary.  A few racing sparks appeared
> after awhile, but a household fan blowing on the gaps helps slightly.
> Eventually the gaps heat and racing sparks appear, although the
> quench on the scope could be seen to remain at 1st notch.

Correct me if I'm wrong but that would seem to be an indicator that
racing sparks are not necessarily (if at all) caused by the 
frequencies present when a beat envelope is present?

A very interesting post indeed. I may comment further at some stage.

Regards,
Malcolm