Hey Olin that is about the most considered answer and best why that the
questioned could be answered. I might even learn from this one lol.

For Marcel as Olin said just think what happens when you have a
capacitor and pass different frequency sine waves through it. 

If you are not shore then I will give you a formula to work with.

_______________________________________

Roy
Tauranga
New Zealand
_______________________________________
> Marcel Birthelmer wrote:
> > apologies for the n00b-ness of my question but being a first-year EE
> > student I haven't learned enough useful things yet to figure out the
> > workings of the following circuit:
> >
> > http://marcel.carrietech.com/phase.png
> >
> > This is a phase shifting circuit (Rv being variable) that I found
> > online.
> 
> Not really.
> 
> > Could someone please explain how to calculate the output
> > voltage given the input voltage and the various components? I've
> > checked all my EE books (which are all intro level, unfortunately)
> > and have come up dry.
> 
> There is a lot that can be learned from this circuit.  It will be well
> worth
> spending some time analysing and understanding it.  However, if I just
> tell
> you the answer you won't learn as much, and I don't want to do your
> homework
> for you anyway.
> 
> Look at the circuit as two parts, the part controlling the opamp
positive
> input, and the part controlling the negative input.  Analyse what
happens
> if
> the input is driven by a symmetric sine wave around ground and the
> negative
> input were held at ground.  For example, let's say it's a perfect
opamp
> with
> +5V and -5V supply and the sine peaks also go from -5V to +5V.  Try to
> figure out what the opamp will do.  If you get stuck, look up
"positive
> feedback" or "hystersis".
> 
> Now forget about what the opamp is doing and look only at the signal
> presented to the negative input.  It's a perfect opamp, so the
negative
> input has infinite impedence.  In other words, it's not there for
purposes
> of analysing what the voltage will be.  That leaves a capacitor in
series
> with the input and a resistor to ground.  What will the result look
like
> for
> a very low frequency sine wave input?  A high frequency sine wave
input?
> 
> That's enough for now.  Answer the questions above to show you
understand
> it
> to this point and we can continue.

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