[Prev][Next][Index][Thread]

"Slinky" Primary / Sloped Archimedes Spiral Primary Equation



----------
From:  Esondrmn-at-aol-dot-com [SMTP:Esondrmn-at-aol-dot-com]
Sent:  Friday, August 21, 1998 2:37 PM
To:  tesla-at-pupman-dot-com
Subject:  Re: "Slinky" Primary / Sloped Archimedes Spiral Primary   Equation

In a message dated 98-08-21 04:11:19 EDT, you write:

<<  Bert -
 
   Thank you for replying to my post. However, it appears that I was not
 specific enough with details and you misunderstood my questions. It is true
 that changing other TC parameters will certainly change the TC output.
 
   What I had in mind and referring to your diagram and equations was only
 changing one variable and that was the angle "X". For example, if a coiler
 had a choice of using a flat spiral or a cone type with R = 3, Z = 5, and
 N= 10 turns which should he use to get the best output? The secondary would
 be a typical H/D ratio of about 3 or 4. The angle could be anything from
 zero to 45 degrees which would require the usual tweaking.
 
   As I mentioned in my post the cone inductances (Lp) vary only slightly
 with angles from zero to about 45 degrees. In fact the differences in this
 case are less than 2 uh of the flat spiral inductance. This is less than
 the normal wiring connection inductances. With secondary inductance (Ls)
 constant the Ls/Lp ratio effect would be very small and within the error of
 actual tests. 
 
   The bottom line is I do not believe it is worth the extra work of
 building the cone type primary because the advantages, if any, are
 negligible. Do you know of any equations or actual tests that would prove
 otherwise?
 
   John Couture
  >>

I agree.  I have built Tesla coils with both inclined primarys and flat spiral
primarys and see no difference in performance.  In one case, my six inch coil
was using a 30 degree (saucer shaped) primary and I was having problems with
strikes down into the secondary and too many hits on the strike rail mounted
just above the outside turn.  I rebuilt it as a flat primary and gained about
7" in clearance from the toroid down to the strike rail and noticed no
difference in performance.

Saucer shaped primarys offer the advantage of allowing easy access for moving
the tap lead to different positions.  When I went to the flat primary I had to
cut many access holes both into the primary coil form base and into the wood
platform that it is mounted on.  Now access is straight up from underneath.
This did allow me to cut several inches off the length of the tap lead.

Ed Sonderman