[sdiy] Re:

[Roman]

Corner frequency depends on both capacitors, but changing
only one of them will change filter's characteristics.
I.e. when the cap at (+) of the opamp will be closer,
there will be peaking, or in another words, resonance.
But anyway it's much easier to make variable resistance
than capacitance. 

Roman

---- Wiadomość Oryginalna ----
Od: Todd Goodenow <toddgoodenow at yahoo.com>
Do: synth-diy at dropmix.xs4all.nl
Data: Fri, 27 Jun 2003 11:13:20 -0700 (PDT)
Temat: 

>
>Ok so lets say you take a simple circuit design like
>so
>http://www.ecircuitcenter.com/Circuits/opsalkey1/opsalkey1.htm
>
>basically a single op-amp low pass filter. Now since
>the frequency of the filter is set by one of the
>capacitors, is it possible to use a variable capacitor
>for variable frequency? For resonance could one set up
>a feedback loop with a potientiometer controlling
>amount? I'm new to this stuff but trying to figure out
>my way along. I want to build a simple filter just to
>get started (i don't want a kit either, I took a good
>physics course and want to understand this stuff from
>the ground up).
>
>thanks, todd
>
>__________________________________
>Do you Yahoo!?
>The New Yahoo! Search - Faster. Easier. Bingo.
>http://search.yahoo.com
>