CGS VCS and DUSG's End out

Calkce · Joined: Nov 13, 2020 Posts: 3 Location: France

Hello,
I'm building a custom quad Slope generator from CGS design (mixing elements of VCS and DUSG), but I'm not interested using the end out gate. I would like to remove it, but i'm wondering if the trig input will still works.

To be specific, i don't understand what's the function of the connection between the 4148 diode and the end out And i'm afraid this "help" the trig to sustain the attack part.

Btw, on the DUSG schematic this connection goes to the pin 4 of the 3900, but on the VCS it goes after the final 1K resistor.

I just read Tim Stinchcombe's page about how the VCS works (http://www.timstinchcombe.co.uk/forums.html?pge=vcs), very interesting, but it didn't clarify this particular part.

Does anyone know something about that?

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cygmu · Joined: Apr 03, 2016 Posts: 9 Location: UK

The diode to the end out is to prevent triggering until the cycle is over. Without this you will be able to retrigger while the slope is falling. I’ve always wanted to try it out but for a basic build I think keeping it per the schematic is a good idea.

Calkce · Joined: Nov 13, 2020 Posts: 3 Location: France

All right, I should have thought to that. I tried both and see now the advantage of the two configurations (with and without the LED). IMO, with the LED, the only thing really interesting is the ability to perform clock divider, and so audio signal subharmonic. But for my use I rather choose to be able to retrig the full cycle whenever I want.
But anyway thanks for your reply.