If anybody can even approach doing justice to the Q concept, including why it matters, in just two sentences, that person will have definitely earned the "Qulitzer prize" in technical journalism.
Here's my entry: "A circuit's Q is closely related to its internal energy losses compared to external energy exchanges. A high Q can mean better efficiency, better conformance with expected performance (especially in filter applications), longer ringdown times (wineglass compared to milk glass) and (unfortunately) higher price." Dana On Tue, Jan 26, 2021 at 8:14 AM Lux, Jim <j...@luxfamily.com> wrote: > On 1/26/21 5:29 AM, Dave Daniel wrote: > > That doesn’t really illustrate the fundamental concept of Q. I’ll try > and think of something that is still non-mathematical but nonetheless > illustrates the concept of Q. > > > > DaveD > > Ultimately, Q is about internal (or external) losses (leaving aside > antennas) - how much energy is stored, vs (how much is radiated) or lost > to heat > > A big heavy pendulum will swing for a lot longer than a light one, > because more energy is stored in the system, relative to the amount lost > to air and mechanical friction. > > And that, like the wine glass (which is a nice mechanical analogy - the > fine crystal has less internal damping) is a "impulse response" system, > not a "driven system" > > > > But how that relates to bandwidth is a bit tricky, because then you need > to get into a discussion "driven systems" and then into resonance - and > that is where the train will come off the rails, particularly with > respect to antennas. > > > > > >> On Jan 26, 2021, at 07:28, Ole Petter Ronningen <opronnin...@gmail.com> > wrote: > >> > >> Hi, All > >> > >> I am going to give a presentation to non-nuts, and in one of the slides > I > >> touch on Q - not wanting to spend more than a sentence or two on the > >> subject, I wonder if the following analogy works: > >> > >> "A quality long-stemmed, thin-walled wine glass will ring for a long > time > >> after we give it a little tap - this is high Q. A thick-walled, stubby > milk > >> glass will barely ring at all, just a dull "plink" - this is low Q. The > >> energy we put in dies out very quickly." > >> > >> As I am sure is embarrassingly evident, I have a rather tentative grip > on > >> the subject myself.. > >> > >> Ole > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
