[sdiy] Filter Frequency response measurement ?

[dj hohum]

So my next question is VCO choice. The ramp is easy a 555 will do the
trick. I know this is blasphemy, but, I was thinking about using a
filter chip as a vc sin osc which will give an exponential readout in
the X domain.

Would I prefer a linear readout in frequency? If so, what's a good
choice for the vco?

tnx,
daryl


On 7/27/07, Needham, Alan <Alan.Needham at centrica.com> wrote:
> That's pretty much what I would do ...
> Ramp (or tri) at maybe 10 Hz driving scope X input (DC coupled)
> and modulating sine osc.
> Sine osc covering required range into filter
> Filter into scope Y input
>
> Why bother with anything else, you will see the response like this,
> it should be good enough to compare topologies or whatever.
>
> A noise source and FFT would be nice if you have it but I don't :-(
>
> 	Alan
>
>
> # -----Original Message-----
> # From: synth-diy-bounces at dropmix.xs4all.nl
> # [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of dj hohum
> # Sent: 27 July 2007 11:08 AM
> # To: synth-diy at dropmix.xs4all.nl
> # Subject: [sdiy] Filter Frequency response measurement ?
> #
> # My understanding of the process is that you use a ramp generator that
> # sweeps the horizontal of my scope in XY mode and a voltage controlled
> # sine wave generator at the same time. You feed the sine wave into the
> # filter and feed the output of the filter into a detector, either peak
> # or RMS?
>
>
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