[sdiy] RC filter questions + SPICE RC filter simulation questions

[cheater cheater]

On Fri, Apr 16, 2010 at 17:20, Richard Atkinson <rga24 at cantab.net> wrote:
> That will sound a bit like a diode ladder filter. Without any buffering
> after the RC circuits, each one is loaded by the one that follows it.
>
> Can you put up some plots showing the frequency response, and in particular
> the bump you refer to?

Of course. I was going to, and even saved off the images, but my
internet died so I got sidetracked. :-) Here they are:

plots: http://img709.imageshack.us/gal.php?g=rc001.gif
schematics: http://img682.imageshack.us/img682/5972/rcschematics.gif

schematic files: http://dl.dropbox.com/u/5958997/rcfilter.zip

Cheers
D.

> On Apr 16 2010, cheater cheater wrote:
>
>> Hi guys,
>> I have been playing around with pspice today, simulating and analyzing
>> some very simple circuits.
>>
>> I analyzed a simple RC filter: AC voltage source goes through R=1kR
>> and C=1uF to ground. I analyzed it and got the familiar curve.
>>
>> Then I stuck some more stages like that on it: there's a series of
>> four 1kR resistors and after each one there's a 1uF cap to ground. I
>> analyzed it and got the expected curve at the last stage, but the
>> first stage has a distinctive bump. Additionally the cutoffs of all
>> the stages are much lower. Where does the bump come from? Is there a
>> specific law that defines this?
>>
>> I am trying to find a way to filter a .wav through the filter and look
>> at the voltage output. Is this possible to do in pspice? If not, do
>> any other spice packages allow that?
>>
>> Thanks
>> D.
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>
>