[sdiy] Filter strangeness.

[Fernando de Izuzquiza]

>No disrespect intended here, but wouldn't it be better
>to have the LEDs in series?

...Is this what make the filter sound talk-boxish sometimes? (listen to
guitar driven samples of the env foll plus filter)
I like the result very much. May be a version with two different LED-control
circuits would rock


---------  mensaje original --------
Enviado por : Scott Gravenhorst <music.maker at gte.net>
Enviado a: synth-diy at dropmix.xs4all.nl <synth-diy at dropmix.xs4all.nl>
Asunto: Re: [sdiy] Filter strangeness.
Fecha: 29-07-04 17:50

> <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
>
>

---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/FatMan/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.
<br><br>
Direccion.com<br>
________________________________________________<br>
This
mail was sent by Direccion.com 2.0