Re: Big Coils (was DOLLINGER)

To: tesla-at-pupman-dot-com
Subject: Re: Big Coils (was DOLLINGER)
From: Esondrmn-at-aol-dot-com (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Tue, 15 Dec 1998 17:12:11 -0700
Approved: twf-at-verinet-dot-com

In a message dated 12/14/98 3:07:16 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes:

<< Original Poster: "Marco Denicolai" <Marco.Denicolai-at-tellabs.fi> 
 
 I have been reading dolnger1.jpg through dolnger8.jpg and I must say it is
 a remarkable piece of infomation! Very useful! I suggest it to everybody.
 
 I also made a Matlab program based on the equation presented in those
 papers and I experimented with different values of k and L1, L2.
 
 According to the equation, top voltage rise at the secondary depends mainly
 on the square root of the secondary/primary inductance ratio (accordingly
 to the formula usually reported by other textbooks). That would give a
 LOWER secondary voltage using big coils (e.g. the new one I am designing)
 compared with small coils (e.g. my old one).
 
 We all know this doesn't hold, but I don't believe that it can be all
 explained saying that you have lower losses with big coils...
 
 
 So how it can be explained that (physically) bigger coils provide higher
 secondary voltages, although they have a lower secondary/primary inductance
 ratio?
 
 
 And more:
 
 using the paper's data, the top voltage rise at the secondary should have
 been about 130 times the primary voltage. Still those guys used 50V at the
 primary, measured about 2 kV at the secondary (factor is 40:1) and
 concluded that the computer simulation gave the same results (!).
 How's that?
  >>
Marco,

Based on the primary and secondary inductances of my two coils (one 3.0" dia
and one 6.0" dia), I would expect the larger coils to have a larger inductance
ratio and higher voltages.  The 3.0" dia secondary is 13.3 mh and the 6.0" dia
secondary is 29.1 mh.  The primary for the 3.0" coil is tapped at turn 15 for
about 57 uh and the primary for the 6.0" coil is tapped at turn 9.5 for 42 uh.
This inductance ratio concept does make you think we should have large primary
caps and only a couple of turns on the primaries.  (The 3.0" coil uses a
.00488 ufd cap and the 6.0' coil uses a .05 ufd cap.)

Ed Sonderman