ISO: time-controlled gate schematic?

[mdcmdcmdc]

Hi folks,

I'd like to start messing about with adding a time-controlled gate to a PT2399 reverb/delay to hopefully achieve a sort of low-rent gated reverb effect. I'm slowly sifting through the copious threads on noise gates, but I haven't been able to find any suggestions on implementing a gate whose length/cutoff time is set externally rather than by input voltage etc.

There's an analog korg gated spring unit, the GR-1, which seems like a promising start but I haven't been able to find a schematic.

Thanks in advance for any direction - I assume this has been discussed in detail... somewhere? I just can't seem to dredge it up on a forum search, unfortunately!

[MikeA]

Here's the owner's manual followed by the service manual which includes schematics:  https://cdn.korg.com/us/support/download/files/d063d020a50fbbf3e72b1572ed018057.pdf

[Eb7+9]

https://patents.google.com/patent/US4584700A/en

[mdcmdcmdc]

https://patents.google.com/patent/US4584700A/en

Is this the rockman or rock box or whatever it's called?

[niektb]

can't you just use a microcontroller that drives a JFET switch?