[sdiy] Envelope to Gate/Trigger circuit?

[eidorian at aladan.net]

On 2013-10-03 22:16, neil harper wrote:
> hey guys and gals,
> i'm just wondering if there already exists a circuit that can output 
> a
> gate and trigger from an existing envelope?
>
> the gate part could be a comparator, going high with an input >0V. 
> that
> seems pretty straight forward. the trigger i suppose would go high 
> when
> a falling voltage starts rising again.. seems like an easy problem 
> for a
> microcontroller, but i have no clue how that would be done analog. 
> any
> ideas?

As often is the case, Ken's your man.  Assuming a straightforward ADSR 
or AR envelope:

Gate (use the "rising" output) - 
http://www.cgs.synth.net/modules/cgs62_sd.html
Trigger (use the "rising" output from the Gate as its input) - 
http://www.cgs.synth.net/modules/cgs24_gatetotrigger.html

Cheers,
A.