And the 555 ADSR does not quite do that. But it can. It has to skip the decay - sustain part if the gate is short, short like not long.
The idea is to control the discharge signal so that it disconnected if the gate goes low before it times out. I don’t know if it works yet but it simulates well. I’ll update after trying it out. Either the BJT or MOSFET circuit or even a load switch should work fine in the location. I like the MOSFET because the body doide works in place of an external diode.
So, I originally linked to a build vid that is, unfortunately, on Patreon only at the moment. I apologize for linking to that. The gist of it is that some ADSRs will behave differently with a long key press than a short flicked key press. If attack is short, sustain is all the way down, and release it turned up, then it produces an interesting behavior. With these settings, a long gate makes a fairly quick attack and decay envelope. A short flick makes an attack and release envelope which is longer. It’s counter-intuitive but Sam explains why that is a good thing in the vid “Building an 1157 ADSR” at about 1:10:50 near the end. If you have Patreon account, you can check it out. The circuit should mostly work like that with the right knob settings. The mod is also swichable in and out.
It works on the breadboard! In the first image, the long gate (or trigger, I wish I knew the difference) shows the ADSR with a fairly fast attack, a quick decay, no sustain and a long release. So all you see is attack and decay.
The second picture shows a gate that is long enough to allow the attack to come up but the decay never starts and it goes right into release. It is a longer note just with a quick key press. It provides a cool effect when playing. (see Sam’s the video on Patreon).
I used the single FET design with an old VN10 I had laying around. It has a Vth of 1.2 and a 3 Ohm on resistance.
…
