[sdiy] why 10V

[jhaible]

> Clipping (what Jürgens question was aiming at) is nonlinear.

That's true. But I would still say the reason of my initial question was
to _avoid_ clipping / nonlienar behaviour. (;->)

> One treats
> transforms like Hilbert transforms in a linear theory where all
> intermediate values can be infinitesimal. But in real circuits thats not
> the case.

I thought the limit was one of causality, not linearity.
For a perfect 90deg shift over all frequencies, you'd need to "see into
the future". If you have a band limited signal (especially omitting
the lowest frequencies), you can introduce a _delay_ for your signal,
to compensate for this "looking into the future". The lower your
frequency range, the more delay you would need. For DC, you would
need infinite delay. (Just imagine what a 90deg phase shifted
DC voltage would look like! - I'm certain Magnus could give
the answer right away, without looking into the books. Hi Magnus!)

What looks like theory straight from the ivory tower (HT of DC) has
a very practical conclusion in the real world: All these Frequency
Shifters that offer two dome-filter-inputs instead of a local
quadrature oscillator, will not be capable of very low amount
of frequency shift. (No slow infinite phasing, for instance)

JH.