[sdiy] Filter strangeness.

[synth at oldmail.charlielamm.com]

This design sounded best to me, and I tried several different variations 
before settling on this one.  

I also hand-matched the vactrols until I found two that sounded good.  
Your suggestion may eliminate that need, but, again I have to trust my 
ears above all else.

If you want to do it some other way, have at it. I encourage everyone to 
experiment and tell the group what they think sounds best.

On Thu, 29 Jul 2004, Scott Gravenhorst wrote:

> <synth at oldmail.charlielamm.com> wrote:
> >> If you wanted a photo resistor to vary cutoff, how
> >> would you setup the input
> >> stage?
> >
> >You can use opamp, with a transistor to up the current it can
> >source...examples on my site.  Look at the circuit fragment surrounding 
> >IC1D.
> >
> >http://www.charlielamm.com/synth/vactrolvcfsch2.pdf
> 
> No disrespect intended here, but wouldn't it be better to have the LEDs in
> series?  Series forces the current to be identical in both LEDs and both
> are guaranteed to light up, whereas parallel means you could have more
> current through one than the other, and you could even have one LED that
> doesn't allow the other one to turn on at all when they are in parallel. 
> It looks like you could have current sharing problems.
> 
> 
> >Vactrol filter page is here.
> >http://www.charlielamm.com/synth/vactrolvcf.php3
> >
> >There are other ways to do this...eg, check out some of the buchla clones
> >for instance on Verbos site, buchla is the grand master of using
> >photoresistors to do clever things.
> >
> >http://www.simple-answer.com/DIY.html
> >
> >
> 
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