I found myself short of an ADSR in my system and it annoyed me to no end I hadn’t thought of buying a few more. Instead of hitting the favourite Eurorack module dealer for my fix I went googling to see if I could cook up one of my own. Couldn’t be that difficult. Right. Turns out, there are tons of useful ADSR schematics floating around on the internet.

Since I didn’t need anything fancy, as I find myself seldom in need of those kind of features, also my excellent Tip-top audio Z4000 has already a lot of bells and whistles should the need arise. A plain and simple, easy to use, ADSR would be perfect. So the ‘feature’ list on this one is pretty straightforward:

  • trigger in
  • Attack, Decay, Sustain, Release (duh)
  • Output (x2)

The only thing I liked to add was an extra output for the ADSR. That way I don’t need to patch a mult in between when I need a second output of the same ADSR. I tend to use this feature very often on my Doepfer A-140 and it’s an easy addition.

I stumbled upon this great design by René Schmitz. (The fastest Envelop in the world) It’s based on a 555 and isn’t a very complex design. I breadboarded one and fiddled around with it for a while and it seemed to be doing exactly what was needed. I changed a few things to have it work properly with 1M pots instead of the 2M2 ones in the schematics ( who has 2m2 pots laying around anyway?). Apart from these little things nothing much has changed as there was little need to do so.. The thing worked great as is. The value of C9 or C11 determine the overall speed, the higher value the capacitor you put in here the longer attack/decay/release times you will get. You can try different values for yourself or add a third option with a 3 way switch.

Schematic

disclaimer: Expect errors

updates

Thank to reddit user /u/Colin___s for pointing out an error on the orientation of  Q1,Q2,Q3.