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I  found this article useful, when I was starting out:

https://aionfx.com/resources/parts-sourcing-where-to-buy-what/

So, I made some progress    Thanks a lot for the input, much appreciated.

I breadboarded the circuit from the first half of the slew pot through to leg 3 of the depth pot.  The input was a 20Hz square wave.  Lowering the value of R39 to 100k had a small effect, it increased the signal from 700mV to 750-800mV.  Changing the ratio of R41,R42 to 9.1:9.1 and 6.8:9.1 (vs 9.1:6. both had a big effect but dramatically changed the behavior of the slew pot making it unusable (Thanks for the suggestion, Zerro!). 

What worked well was decreasing the value of C38.  Changing from 100n to 82n gives takes the output voltage close to 1V.  I'll add a socket in the build and test out some values when I can hear the effect. 

Now what I'm wondering is if the slew pot is implemented correctly?  The B half of the pot effects the shape of the output signal, it warps the triangle slightly in the first part of the rotation then pushes it more towards a square wave around 50% of the turn.  The last half of the turn flattens out the signal completely.   The A half of the pot just cuts the input signal as it is turned up. 

I'm wondering what the function of the A half of the pot is?  My input signal was 2V, maybe the output from the Attiny is larger and the A is needed.  Any ideas?  I'm contemplating using a single pot instead of the double.

Thanks Thomas! 

I've didn't find any examples of integrators that were also amplifiers.  Still learning this stuff. 

I'm looking for ~2X amplification, so, the second suggestion is going to be better for me.  I tried to breadboard this and mess with switching values, but I couldn't get it working.  I'm going to give it another shot.

This is the modulation section from Fairfield Circuitry Shallow Water.  The circuit produces a subtle effect, so, I'd like to increase the amplitude of the modulation signal and give it more range.  I'm in a little over my head here, so I was hoping someone could take a look and see if I'm understanding things correctly. 

The Randomizer is an Attiny chip producing a random square signal.  I'm interpreting the next steps as a unity gain buffer followed by an integrator.  I'm confused about the set-up of the slew control and whether or not changing any of the values of the integrating op-amp will affect the gain.   What I'm thinking about at the moment is bending out leg 2 of the MCP602 and connecting it to R64 via a resistor to create an inverting amplifier from the buffer. 

I'd love to hear what some more skilled people think. 

Great build, Dan!  Love the video.  It reminded me a little of the Wipers, Silver Sail in the beginning, which is a great album.

And thanks for the dredge bump... I missed this build!  Sweet looking pedal Bio

Thanks man!  Hitting it up on its anniversary 

Stomp Box Parts has FV-1s and 571s. 

Looks awesome!  Congratulations!

JFETs (e.g., 2N5457s).  I had just grown comfortable with the fact that SMD was going to be the new format for these, but MMBF5457s are gone too.

Awesome work, Dan!  I'm with Grant on the Belton Brick in a 1590A!! That's something I've never seen.   

Did you try the circuit outside of the box?  I'm a bit worried about the metal DC jack.  The convention is pedals is center negative, which would short your power to ground unless I don't understand the jack you are using.   

Badass!   I love to see these weirdos in the wild.

If you are into it, get a keg system, bottling sucks!

So much easier. But also, so much easier to drink it faster. If the glass never gets less than halfway empty, you're always still on "my first one". 

Fun side note: For about 5 years, I wrote a regular column in Brew Your Own magazine (the Projects column).

This was an ongoing joke at my house, when I had regular kegs.  My wife would ask, "how many beers have you had?" and I would reply, "I make beer, I don't count beer" 

That's cool, about the magazine.  I never made the plunge to whole grain.

Bio77, you homebrew?

I have a Muntons Yorkshire Bitter bubbling away, probably due for bottling right now.

Yeah, I brewed pretty regularly several years ago, not so much anymore (I have a new hobby  ).  However, it was a super handy skill early in the pandemic.  I made 3 batches right after the first lock down.  Kept me from having to do any beer runs for quite a few months.  If you are into it, get a keg system, bottling sucks!

My garage is a mess but my work station is super neat at the moment    I made a lot of key updates at the start of the pandemic because this doubled as my home office when the whole family was here online.  The most important improvement was a nice chair. That's a solid state Princeton, so, I guess I need to step up my game.