On 05/02/2011 11:43, V G wrote:
>> 4. The the gain setting resistors on the second opamp are 220K each,
>> >  designed to give the opamp a gain of 2. Do they really need to be 220=
K each?
>> >  Or can I just use something like 1K each instead? What difference doe=
s it
>> >  make, as long as the ratio is the same?
>> >



Not much to add apart from that I noticed on the page you linked to has=20
the bandpass filter cap value wrong for the LP part - it should be 10nF,=20
not 10uF for 107Hz (disregarding loading). IIRC these were the same=20
values you posted a little while back. Given this (and in general anyway=20
- I share Olins views here, don't assume some random person knows=20
something just because they put it on a web page - plenty of utter=20
nonsense out there) you should check the notch filter values and any=20
other calculations yourself.
Also remember opamp input impedances can vary hugely - e.g from ~100kohm=20
to above 2Gohm - so what may work with one might not for another.


--=20
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