[sdiy] ADSR Question

[Scott Gravenhorst]

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?

=========================================================  
- Hydrogen is pointless without solar.
- That which gets rewarded, gets done.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/FatMan/
-- NonFatMan: home1.gte.net/res0658s/electronics/