[sdiy] vactrol panning (across 4 outputs?)

[alfred.pear at gmail.com]

Tom -

I was under the impression that a scanner shifted from inputs, rather
than sent a single input to multiple outputs - so I'm apologize for my
lack of clarity...

The goal is a circuit that will take one inputs and "pan" it across
four outputs, one by one, with a single voltage, preferably in a
compact design similar to the simple panning implementation (sorry
Aaron).....

I was hoping there might be a way to put a current mirror inside the
current mirror...but I don't really know..

-M


On Sun, Jan 16, 2011 at 8:24 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
> Sorry Alfred, I'm not quite clear what you're trying to do.
>
> Do you want the two extra channels to be copies of the existing two channels, or are you aiming to build a 'quadraphonic' version of the circuit?
> Or do you have a 'four channel scanner' circuit in mind, where the output can be 'panned' from output 1 to output 2 to output 3 to output 4 under the control of a CV?
>
> The circuit itself looks to be a pair of "optical" VCAs, as used in many famous compressor designs (very simple audio path, so low noise, and the slow LDR response gives a natural sound). The vactrol's LEDs are driven with a current mirror, which provides the panning action (one goes up whilst the other goes down).
>
> Thanks,
> Tom
>
>
> On 16 Jan 2011, at 05:00, alfred.pear at gmail.com wrote:
>
>> hi synthesists -
>>
>> i'm sure many of you are familiar with this very elegant two-channel
>> panning circuit, using two vactrols (based on a buchla design,
>> apparently):
>> http://www.simple-answer.com/vac-panner.jpg
>>
>> i feel like there must be a way to nest and scale several transistors
>> in there to make this circuit response across four channels of
>> output....but i'm not a very skilled designer..
>>
>> any suggestions?
>>
>> sincerely,
>> a. p.
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>