Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcdc!hpfcdj!myers
From: myers@hpfcdj.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: Meta HV Cap Fun!
Message-ID: <11170010@hpfcdj.HP.COM>
Date: 6 Jun 89 17:51:30 GMT
References: <682@uvicctr.UVic.ca.UUCP>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 33

>1) Is is possible to make such a circuit with zero effective inductance
>assuming that the geometry of the circuit can be ideal?  What is this
>gemometry?

Off the top of my head, I don't believe that this can be done.  Inductance
results from the magnetic field induced around any current-carrying conductor;
therefore, if charge is to be moved any distance at all, a field will be
produced and so inductance will be present.

Coaxial and twisted-pair conductors negate this effect by arranging the
"forward" and "reverse" (or "source" and "return") currents so that the
induced fields from each are in opposite directions.  Given equal magnitude
currents, then, the fields exactly cancel and there is no (realistically,
very little) net inductance.  However, I do not believe that one can arrange
this circuit such that all fields cancel, in light of the fact that we're
still talking about putting two capacitors in there somehow, and the current
*must* physically separate by some small distance to make this connection.
Thus, there must always be some net inductance.

>2) Build such a "tank circuit"  in some way that prevents it from radiating,
>such a coaxially, maybe.  Dunk it in liquid He so that it superconducts.
>Does it now oscillate forever?  Remember, this is a real device, not ideal.

No can do, for similar reasons.

Of course, this response comes after a *very* quick consideration of the 
matter, and there may indeed be some novel configuration which at least
approaches this ideal.  Anybody found it yet?


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers%hpfcla@hplabs.hp.com               |  sentient life-form on this planet.