[sdiy] fanning grounds vs. dirty/clean ground

[René Schmitz]

>For fast applications (audio), you
>* must make the capacitive load very small, or
>* isolate it with a resistor (as you did), or
>* use two separate feedback paths (needs some calculation).

a brute force option: interpose a buffer with a very low output
impedance, and take the feedback from its output.

>For DC buffer applications, just make the cap *big*. So big, that
>the resulting pole is outside the critical range _on the other side_.
>Example: LM324 as unity gain buffer for DC - > add 10uF directly
>from output to GND.

Obviously for the "buffered" GND, the cap would need go to either pos or neg 
rail, never to the direct GND, as this would be against the purpose of 
isolating the two. 

Cheers,
 René


-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159