[sdiy] Schmitz ADSR replace pots with CV control?

[Tom Bugs]

Yep - I'm still curious as hell about this too!
I did play around a bit in LTSpice but.. 2164 tests definitely weren't 
playing ball like this.
What am I / are we missing? Or should I be trying this 'physically' 
(hard given my current setup for sure..)
Cheers, Tom

On 26/11/2013 09:41, Mattias Rickardsson wrote:
> On 26 November 2013 08:19, David G Dixon <dixon at mail.ubc.ca> wrote:
>> If you put a resistor in series with a 2164 VCA, then you essentially have a
>> voltage-controlled resistor. When the VC pin voltage is 0V, then the
>> resistance is that of the fixed resistor.
> The normal way of connecting the 2164 is at an OP-amp's virtual earth
> summing node. Then it's true that it "looks like" a variable resistor
> seen from the OP-amp's point of view, since the 2164 provides a
> current that is VC controlled.
>
> But from the 2164's input side, it doesn't. It's just a regular fixed
> resistor connected to another virtual earth. So it will not, say,
> drain a capacitor in a voltage-controlled manner with its input. Also,
> the 2164 is supposed to be connected to a virtual earth in order to
> behave as specified, so I'm not sure if you could just put a 2164 in
> the place of the pots in the drawing, regardless of the voltages
> around them. But I haven't tried it! :-)
>
>>   This worked extremely well in the Quadra.
> Hurrah!
>
> /mr
>
>
>> ________________________________
>> From: navelludd at gmail.com [mailto:navelludd at gmail.com] On Behalf Of Mattias
>> Rickardsson
>> Sent: Monday, November 25, 2013 10:48 PM
>> To: David G Dixon
>> Cc: synth-diy at dropmix.xs4all.nl; Jack Jackson
>> Subject: RE: [sdiy] Schmitz ADSR replace pots with CV control?
>>
>> I don't quite see how that would be done with a 2164... do you have a
>> sketch? :-)
>>
>> /mr
>>
>> Den 25 nov 2013 22:17 skrev "David G Dixon" <dixon at mail.ubc.ca>:
>>> No, a single 2164 would do nicely, with one VCA to spare.  The response
>>> would be exponential, as it should be for an envelope.
>>>
>>>> -----Original Message-----
>>>> From: synth-diy-bounces at dropmix.xs4all.nl
>>>> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of
>>>> Mattias Rickardsson
>>>> Sent: Monday, November 25, 2013 7:38 AM
>>>> To: Jack Jackson
>>>> Cc: synth-diy at dropmix.xs4all.nl
>>>> Subject: Re: [sdiy] Schmitz ADSR replace pots with CV control?
>>>>
>>>> With Vactrols, would be the simplest solution... if you can
>>>> live with the drawbacks of slow CV response and possibly
>>>> weird range. Anything more advanced would require a very
>>>> different circuit, I'm afraid.
>>>>
>>>> /mr
>>>>
>>>>
>>>> On 24 November 2013 19:52, Jack Jackson
>>>> <jackdamery at hotmail.co.uk> wrote:
>>>>> I was looking at René Schmitz's  ADSR 2. It looks like a
>>>> neat little
>>>>> design, but I was wondering if it would be possible to
>>>> adjust it to take 0-5v CV for the parameter control instead
>>>> of using potentiometers directly in the circuit?
>>>>> http://www.schmitzbits.de/adsr2.png
>>>>> _______________________________________________
>>>>> Synth-diy mailing list
>>>>> Synth-diy at dropmix.xs4all.nl
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