AW: vc adsr

[Beszedes Arpad]

Hi!

Took a look at your homepage (and the adsr schema) and I can tell you
that you have some really great stuff there. I think that this is what I
wanted, thanks!

By the way, maybe this is a _REALLY_ silly question, but I simply have
to ask this: what does DIY really mean? (or am I too stupid for this
list?)    ;-)

Bye,  Arpad

Haible Juergen wrote:
> 
>         >I like the idea of using OTAs as current sources (maybe CA3080,
> beacuse
>         >it's cheaper than the LM13600), the problem is that to use it as a
>         >general vc-resistor (floating) it needs 2 opamps, so the circuit
> could
>         >be too complex (and expensive).
> 
> You don't need 2 opamps, really. You can build a VC RC lowpass
> (i.e. floating resistor connected to grounded capacitor) with just
> 1/2 LM13600 and a JFET. See my homepage for a complete
> VC ADS (easy to expand to ADSR with a couple of CMOS switches).
> The only (well known) problem with cheap OTAs in envelope
> generators is offset voltage. But it works nicely on VCFs and
> cheap pseudo linear VCAs nevertheless.
> 
> If you want an OTA solution withoutout offset problems, Joachim
> Verghese is your man - he's on the list, too.
> 
> JH.

-- 
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*  Arpad Beszedes                             *
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*  Research Group on Artificial Intelligence  *
*  Hungarian Academy of Sciences              *
*  Attila Jozsef University, Szeged, Hungary  *
*  e-mail: beszedes at cc.u-szeged.hu            *
*  tel.: (+36) 62/45-41-45                    *
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