[sdiy] (easy) resonant filter

[TooManySynths]

Without a doubt, what you guys need is any book by
Delton Horn.  His books are chock full of awful
designs that use an average of six parts
each..including the input and output jacks.

I built the scr vco from one of his books, and kind of
got it to work...sort of.

I understand the issue of having parts in your bin and
wanting to make something with them.  However, the
simplest designs to build are based on CEM/SSM chips. 
The 3328 is so easy to use it practically builds
itself. 

I'll see if I can dig up one of those awful Delton
designs for ya though, hopefully it will work.

Daryl


--- Tim Escobedo <tpe123 at yahoo.com> wrote:
> Go to http://www.planetee.com/ and search the Ideas
> for Design articles
> (you'll have to register for this one) for the April
> 30, 2001 article,
> "Second Order Audio Filter Performs Multiple
> Functions". It's a rundown
> on a nice state variable filter design using
> inverting op amps and
> describes how to independently adjust gain, cutoff,
> Q, with various
> responses.
> 
> The simplest resonant filter I know of is a bridged
> T or twin T using a
> single opamp (or even transistor). They can sound
> pretty good even
> though they seem to commonly be implemented with
> fixed resonance. These
> can be easily put under voltage control too.
> Unfortunately, i don't
> know of a really good online resource describing the
> ins and outs of
> this design. There is an article in PAIA site
> describing a "drum
> oscillator/filter" that is a basic voltage
> controllable twin T using a
> single op amp. 
> 
> --- Tavys Ashcroft <bigtex at cwnet.com> wrote:
> > >can anyone pont me towards the worlds simplest
> resonant filter
> > schematic-i'm
> > >bored an want to build something, doesn't have to
> be voltage
> > controllable,
> > >but no CEM chips (preferably, just diodes, and
> simple op amps).
> > nothing
> > >fancy. or anything else realy simple and fun.
> >
> > Actually, that's exactly what I'm looking for too.
>  I just bought an
> > unbelievable number of opamps (400 I think) from
> BG Micro for about
> > $8, and want to put them to use (yes, they're
> 741s, but I'm not
> > worried about it, I'm learning).  They're quad
> opamp chips, so I
> > figure 1 opamp for the input buffer and 3 for the
> filter, giving me a
> >
> > 1 chip filter.  Then I could make lots of them and
> have them really
> > tiny and give them out as party favors or
> something.  Is there an
> > easy tuneable filter (HP,LP, or BP, resonant or
> not) that can be made
> >
> > with three opamps?  I also don't care about
> voltage control,
> > linearity, a perfectly clean signal, or anything
> really.  I just want
> >
> > to experiment with filter design and I need a
> starting place.  I've
> > looked around and all the schematics for filters I
> find require some
> > sort of CEM chip.
> >
> > -Tavys
> >
> 
> 
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