FX30 noise gate - longer decay?

[blackieNYC]

I'd like to extend the maximum decay time of my DOD FX30B.  schematic http://www.americaspedal.net/fx30b/fx30bschem.jpg   shows the "Delay" pot.  I don't understand what's going on with the inverting input there, and the 4148s, if somebody can lay that out for me that would be great.  I could just try it, but I suspect my solution is not to add to the 100K pot.  That would be too easy.  Pessimistically thinking the maximum delay is at the pots minimum resistance setting.
Kipper4 asked the same question years ago but there is no answer in the thread.  Where yat, Kip?
That J113 Jfet there is N channel.
I love this thing otherwise.  I have all the wacky noisy stuff in the loop, and I set it to gate the loop return instead of the input.  Quite neutral, but I'd like to True Bypass it sometime.

[duck_arse]

try increasing that 1uF hanging off the inverting input and delay pot. maybe.

[Mark Hammer]

Does this drawing provide any better clues?

[blackieNYC]

Interesting, Mark. The delay pot in your drawing is 500k vs the DOD drawing's 100k, and the cap C4 is 10u on yours, 1u on mine.  Think that's an improvement in decay time?  Seems like it might.
Your drawing says "FX30" which I think may be inaccurate. I think the "B" version was the one with the added fx loop, which your drawing contains.
I need to crack mine open and see what values are actually in there.

[Mark Hammer]

Notwithstanding the possibility of 'B' versions, and different issues of the FX30, I was under the impression that it had always had the loop, such that the initially drawing you showed was a stripped down version.

Actually, some clever tricks in the experimentalistsanonymous factory schem.  Consider...

The gain of U2A is set by the 500k Sensitivity pot.  Whatever portion of the pot's resistance is on the CW side of the wiper is added to R4 to set the gain.  On the other side of the wiper (CCW side), we have a resistance that is in parallel with R7, going to ground.  And that resistance is in parallel with C1, effectively changing the discharge time of C1, such that the higher the gain of U2A, the longer the C1 discharge time.

Neat!

[blackieNYC]

Do you think C1 affects the decay time? Or C4?
On another front, Mark, I know you've looked into this before - the MXR gate uses a fet which conducts and drains off the signal to Vb. muting. This DOD turns the Fet (in series with the audio) on, and it conducts the otherwise muted audio. I'm guessing I could put a large pot across the source and drain to get an attenuation control, think so?

[Kipper4]

Hey Blackie
I'm back.
Why do you want to extend the decay time?
What's the goal please.
Rich

[Mark Hammer]

Do you think C1 affects the decay time? Or C4?
On another front, Mark, I know you've looked into this before - the MXR gate uses a fet which conducts and drains off the signal to Vb. muting. This DOD turns the Fet (in series with the audio) on, and it conducts the otherwise muted audio. I'm guessing I could put a large pot across the source and drain to get an attenuation control, think so?

That sounds plausible.  I know the J113 will drop down to 200R or less when "On" but I don't know how high it goes up to when "Off".  So the required pot value may be hard to get or wacky.  You may simply want to opt for a 3-position SPDT toggle to select resistance values for "full", "medium", and "courtesy" (attenuation).

[blackieNYC]

Kip- the decay time is awful short at the maximum setting. Haven't timed it but it cuts off way too fast. I'm sure I would prefer it to be doubled. 

[Mark Hammer]

If yours is the same as the factory schem I posted, then consider disconnecting the rectifier gain from the decay time by using the Sensitivity pot for ONLY Sensitivity, and using a second pot to set the pot+R7 resistance and drain-off time of C1.  As is, the one pot has the reciprocal action I described earlier.

[Kipper4]

I think I built a stripped down version with out the loop.
If I'm thinking right that's everything below r30 and D5.

Edit
Just found the schematic for the one I built over the other place.
Hut humm

[PRR]

As a general thing when tinkering speed/rates....

Leave the resistors alone, change the caps.

I can't see (403) your image for #1. In Mark's image, C1 is maybe attack, C4 is maybe release. Unless the internal logic is inverted? What-eveR, tack 10u across c1, hear what happens; un-do and tack 100u across C4, hear. This will probably get you there quicker than thinking.

[blackieNYC]

My gut reaction was to avoid thinking and start tacking on caps, but then Mark comes along with his.. thinkiness!  I'll tear this thing up and see what I can find.  I'll explore the partial attenuation thing as well.