From: boris petkovic
Date: Thu, 28 Dec 2000 02:35:59 -0800 (PST)
Subject: Re: [TSSP] early idle testing
> > Msms of even very high Q coils show that there is > > small,but not negligible declination from 90 deg > rule > > between bottom and top voltages. > > Few degrees allmost always. > > I must think carefuly what does this mean. > > Yes, if the drive signal is not exactly at the > resonance. > > If the drive is slightly above resonance, the top > voltage > lags the base drive voltage by a little more than 90 > deg, > > Slightly below resonance, the top voltage lags the > base > by a little less than 90 deg. ---- By resonance frequency you consider the exact frequency where input impedance of the resonance reaches its minimum? ----- > > There are no phase discontinuities, so somewhere in > between > the phase must cross -90. > > For a coil resonating around say 150 kHz, the top > volts > phase goes from 87 deg lag at Fo-10Hz to 93 deg lag, > at > Fo+10Hz, a change of 0.3 deg/Hz, so you need to be > exactly > at the resonance. > ---- Requirement for such precision,for high Q coils especially,explains all the difficulties associated with msms of this kind (and the variety of the test results I have seen). The phase shift I pointed to is extra sensitive near Fo. Regards, Boris __________________________________________________ Do You Yahoo!? Yahoo! Photos - Share your holiday photos online! http://photos.yahoo.com/
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.