From: Paul
Date: Thu, 17 May 2001 18:25:39 +0100
Subject: Re: [TSSP] Measured vs. Operating coil coupling?
Hi Terry, All, Terrell W. Fritz wrote: > ...Dryer duct toroid tend to have strangely poorer performance > than smooth toroid. Perhaps this is a truly new concern for > toroid builders! It would be interesting to know where abouts the average toroid sits in relation to the curves in http://www.abelian.demon.co.uk/tssp/tmp/eddy-coupling.gif in other words, is a dryer-duct toroid more resistive than the 'worst case', ie somewhere between the green curve and the blue curve, or is it less resistive, ie between the green curve and the red curve? If the former, then reducing the resistance may make things worse. And how about a spun aluminium toroid - where does that sit? In view of the small Fres shift reported by those who have tried cutting the toroid, it may be nearer the blue than the red. Plenty of room for useful experiments with this. Eg, take a toroid with a radial cut. Measure Q and Fres with a range of resistances bridging the cut. Should be able to form a graph showing the locus of the response peaks (imagine a U-shaped curve joining the peaks of the three curves in the image, touching the peaks of all the intermediate response curves. Question boils down to whether or not the resulting curve shows the whole U, or maybe just the left hand half, ie with zero bridging resistance the response doesn't go as far down as the green curve, and never gets up the other side because the toroid resistance itself is too high. It should be possible to demonstrate a U-shaped locus of the coupling by doing the above expt using the primary, with a variable resistance across the primary terminals (no gap, no cap), and CW feed into the base. Most interesting for me is the possibility of preventing the magnetic field from going into the ground - but that test will have to wait till the weather improves. Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.