[sdiy] ADSR Question

[Oren Leavitt]

Hmmm...Maybe you need to set the maximum voltage going to the RC circuit 
to a point just above that 1/2 Vdd level or use a comparator between the 
RC and the 4069.

Scott Gravenhorst wrote:

>I have played with several designs for ADSRs.  My question
>regards the attack curve.  In my lastest design, I used a
>4069UB to make all of the logic.  Because I use a gate as a
>threshhold detector, the attack portion ends when the
>integration cap reaches 1/2 Vdd.  This gives a fairly
>straight line for the attack curve.  I tried playing divider
>games to get it detect at a higher voltage, but the circuit
>became erratic when I pushed this too far.  I believe I was
>able to get it to work reliably up to about 2/3 Vdd where it
>looks pretty nice and rounded.
>
>Is there a standard threshhold that is used in most ADSRs? 
>If so, what is it?
>
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