[sdiy] Shruthi 4PM (was re something else...)

[Neil Johnson]

Roman Sowa wrote:
> For example in notch filter the notch comes from summing 2 signals at
> certain frequency shifted by exactly 180 degrees

Notch and bandpass are the tricky ones indeed since we're trying to
align two or more cutoff points relative to each other.  Low pass and
high pass are certainly easier - any variation in the pole locations
will just smear the filter knee and soften the resonance.

> Let's go further - 0.1% resistors are not a big deal nowadays, I buy them
> for about 0.25EUR, but precision capacitors is a whole different story. OTOH
> I never needed them so far, so I may be wrong. Also you can always add a
> trimmer cap.

1% C0G capacitors are common these days for relatively sensible prices.

Neil
--
http://www.njohnson.co.uk