Re: Tesla humor and I hope I get this right this time!

[Esondrmn-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

In a message dated 8/25/00 8:43:19 PM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

<< Original poster: "Garry F." <garryfre-at-pacbell-dot-net> 
 
 There once was a man named Birquette.
 Whose Tesla hobby put him in debt.
 While adjusting his gap, he got a large zap 
 and now he's a charcoal bricquette!
  
 Now the question. Yep, I made up the above limmerick
  
 I keep mis-stating the thickness of the polyethelene between my stack cap by
 mentioning the thickness of an individual sheet instead of the total 
thickness.
 Well, this makes the eighth try and if I get it wrong this time, I guess I
 don't deserve the answer.
  
 Each plate is separated by four .012" sheets for a total of .048 thickness. I
 hope I got the decimal place in the right place.
  
 The area of overlap on each plate equals 26 square inches.
  
 The transformer is a 12/30 NST. When I try to calculate the value of the cap,
 and compare it to what I see in some plans I have, the figures don't make
 sense.
  
 What I need is a reccommendation on the number of plates I should use in this
 cap for a LTR cap. I guess I want between .80pF to 1.00pf or is that supposed
 to be uF?
  
 According to an online wintesla that I lost the link to, my secondary 
resonates
 at 450mhz?? It's a thick wall OD of about 3.5 inches the wound area is 24" 
long
 with #29 wire. 
   >>
Gary,

OK, using a dielectric thickness of .048, I calculate about 279 pf of 
capacitance per plate - this is one stack of two plates separated by one 
thickness of .048" thick polyethelene.  This is assuming a dielectric 
constant for poly of 2.3.  For a .008 uf cap, you would need about 29 plates 
(30 metal plates and 29 sets of poly.  For a .01 uf cap, you would need about 
36 plates.  It would be good if you could borrow a capacitance meter 
somewhere and actually measure the value of the stacked plate cap.  I would 
still caution you about running this cap dry - oil is necessary to keep from 
puncturing the poly.  You still need to do the calculations to make sure the 
resonant frequency of the primary (tapped at about 80 or 90% of full turns) 
with this value of capacitor will match the resonant frequency of the 
secondary, including the toroid.

Good luck, Ed Sonderman