From: Paul
Date: Sun, 24 Mar 2002 21:28:34 +0000
Subject: Re: Ready :-)) - Re: [TSSP] short H/D and stuff
Hi Terry, There's only one possible doubt about this experiment - when the coil is pinged, the base is grounded not directly, but through the tank capacitor - 50pF I believe. With an equivalent shunt capacitance of only 10.65 pF at f1, this is enough to give a reasonable facsimile of a grounded base, but it does give some cause for concern. The predicted current profiles assume a firmly grounded base. The effect of this capacitive ground connection would be to raise the current max even further up the coil, and to increase the current at the max. Unfortunately I can't quickly reconfigure the model to check the effect of small series C in the ground connection. Can you specify just what the pinging circuit consists of, and is it possible to use a larger tank C for the impulse, say 500 pF? If Fres doesn't alter more than 1% on going from 50pF to 500pF I'd say the effect on the current profile would be neglectable. The fact that the model already gives a good account of the coil's resonances is encouraging, and means I'm probably worrying about nothing. -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.