Korg Poly-800 New (as in nobody did this before) Mod in progress - help needed

[YashN]

Once I finished and finalized the usual common mods (Moog Slayer, 12/24dB switch, FM-800, Audio Into VCF), I started experimenting with the Chorus board and sometimes its interconnection with the main board.

There is one mod which is potentially very musical and interesting, but for this, I need help tapping into the key or MIDI sections of the main board and also a small circuit.

Here is what it needs to do:

It needs to output an ON signal on every Key ON, maintain that state for a very short time (up to .5s), then it needs to go OFF without waiting for Key OFF.

I swear this is going to be good! 

[Bogus Noise]

By chance, I potentially have the exact circuit you're after in the tab right next to this

http://www.cgs.synth.net/modules/cgs24_gatetotrigger.html

I say by chance, because I read your post a second time, and am now not sure if the trigger it gives will be too short for you. Does it need to be adjustable?

[YashN]

Hey thanks, BogusNoise, I was looking at Ken's CGS site a lot but hadn't seen this.

I think it could be useful. The circuit may yield different valuable results if there is an adjustable pot or so, but it's not necessary in the beginning.

[Bogus Noise]

Cool, yeah even if it doesn't quite work out, you should be able to knock up some kind of mini on-off envelope circuit with a 555 or something better. Basically to act like an envelope hold function with a very small range, and use the Gate to Trigger to trigger it.