[sdiy] AD/AR design posted

[Ian Fritz]

Hi folks --

Going through some of my circuit documentation I realized that I have a 
nice AD/AR envelope design that never got published or posted.  Looking 
around at some of the designs on the web, I decided that this design really 
needed to be made available.  :-)

It's built around a quad op amp with no other active components.  It has a 
single input that can be driven by either a trigger or a gate signal to 
produce either the AD or AR envelope.  It has compensation for the voltage 
drop across the steering diodes, so that an accurate exponential is 
produced (no extraneous long tails).  It has a feedback loop to accurately 
hold the output at zero in the off state.  And it has the capability to 
produce truncated envelopes, useful for making VCO chirps without a long tail.

I have posted this design, along with an auxilliary delayed pulse generator 
circuit I sometimes use to drive it.

For your enjoyment or other amusement:
http://home.earthlink.net/~ijfritz/sy_cir12.htm

   Ian