From: Paul
Date: Sun, 24 Feb 2002 18:10:59 +0000
Subject: [TSSP] Software for flat and conical secondaries
Hi All, The modeling software is now modified to work on flat spirals and cones. It fails dismally to reproduce Dave Thomson's 325kHz from his flat coil. I get 625kHz. I'm afraid that's the only measurement I've got. Fres measurements from flat and conical secondaries are most welcome right now. I'm expecting trouble from material dielectrics, in the same was as with short h/d solenoids. So it would be best to avoid coils wound on thick slabs of dielectric. VI profile predictions look encouraging. http://www.abelian.demon.co.uk/tssp/tmp/dt1.624247.gif You see the current peak is well out from the center, and as hoped, the effective inductance is high: Lee: 9.60 mH Les: 7.70 mH Ldc: 6.25 mH Les is 23% above Ldc, and Lee is 54% above. However, the transfer impedance is low, only 30K ohms. Internal capacitance distribution, http://www.abelian.demon.co.uk/tssp/tmp/dt1.cint.gif External capacitance distribution, http://www.abelian.demon.co.uk/tssp/tmp/dt1.cext.gif With this model, there is next to no external capacitance near the center of the flat coil. I'm not modeling any supports or anything. Hence, no longer a bathtub shape. The capacitances are: Cee: 10.53 pF Ces: 8.44 pF Cdc: 12.68 pF We see that Cee is very high for this coil, which explains the low transimpedance. Normally it is around half (ish) of the DC capacitance. Were it not for that, we would see the full benefit of the high effective inductance - the transimpedance would be around 60kohm. So that's a little disappointing. Still, its early days and there's plenty of room for bugs in the code. I think now's the time to do some careful validation measurements on flat coils. Cheers, -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.