[sdiy] expo accuracy? or integrator accuracy?, or both?
ijfritz at earthlink.net
Fri Feb 7 20:42:48 CET 2003
Hi Magnus --
> > The objection seems to come from soakage, not from tempco.
> > Fortunetaly it seems that soakage has not such a great impact
> > in vcos then on s&hs.
>Since it is hysteresis just look how the counterpart of the capacitor, the
>inductor work in this sense... the hysteresis causes losses, but frequency
>error? No, I don't think so.
Oh, I think it definitely could.
The origin of soakage/hysteresis is the slow dynamics of molecular or
domain reorientation. If there is a relaxation component in the audio
frequency range, then you will get more reorientation (wider loops) at low
frequencies than at high ones. Furthermore, these processes are usually
thermally activated, which means potential exponential increases in their
effects with temperature.
Even worse, there can be memory effects that will cause the exact shape of
a loops at one frequency to vary in time depending on previous history. So
you might not even get the correct initial pitch if you jump from low to
I spent some time studying these effects in ferroelectric ceramics. The
time scales range from microseconds to years in this case. Hopefully mica
isn't so bad!
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