Panspermia Build Documents vs My PCB

[debrad]

Finally getting around to building my Panspermia (PCB112) and I think I just ran across an issue between the build documents and my board:

On the bottom row of the board, I have two 10k resistors on the left while the documents show a single 10k resistor beside two 100n caps. This seems to give me five 10k resistors on my PCB while the build documents only have four...

Here's mine:


Here's the build document:


In addition, one side of R2 (10k) on my PCB board has a direct connection to pin6 of the OpAmp and no connection to Q1 while the schematic in the build document shows R2 connected to the collector of Q1 and no connection to the OpAmp (having said that, I think they both connect to VCC...).

Bottom line, is it possible that there is a different set of build documents that match my PCB...and can anyone explain why my board layout appears to include 1 more 10k resistor than the schematic?

 

[Robert]

I'm working on getting the doc updated for you now.

In the meantime, omit the 10K that you don't have installed in the picture above.

Follow the silkscreen on the PCB for everything else.

 

[debrad]

Thanks @Robert.

So, based on your response and a little more probing around my PCB, it appears that the 2nd 10k resistor on the bottom left side of my board is a duplicate of the 10k resistor labelled "R2" in the build documents...is that correct (one end of each connects to "R1" and the other end of each connects to pin6 of the OpAmp (which, in turn, connects to "VCC"))?

If so, I should be able to omit either the 10k that I "don't have installed in the picture above" as you suggested, or the 2nd 10k from the left on the bottom row that I do have installed...correct?

As for the rest of the board, the silk screen seems to match the build documents nicely. You may have noticed though that I have installed D1 and D2 in reverse and also swapped the 1N34a with a 1N4148...both mods recommended by @aelling in this post: https://forum.pedalpcb.com/threads/...f-these-sustain-control-issue.7660/post-73663

 

[Robert]

Yes, you could omit either.

I just figured it would be easier to omit the one that wasn't installed yet.

 

[debrad]

I appreciate that @Robert - fortunately, I haven't soldered any of those components in place yet so I have some flexibility!

 

[debrad]

FWIW, @aelling's recommendation on changing the orientation of D1 and D2 did NOT work for me. Reversed from the build documents, I had loud thick fuzz with the Sustain fully CCW and quieter thin octave fuzz fully CW but something VERY unusual around the centre of the control..."strange" like pulsing noise that was somewhat in line with picking dynamics but nothing like what I might expect from even the mostly glitchy, gated, velcro type of fuzz. It just didn't seem right.

Reorienting the diodes to match the build documents gave me the full range between loud and thick (CCW) and thin quiet octave (CW) in as smooth transition which closely matches the demo's I've heard.

 

[leadfoot]

@debrad would you mind posting a picture of your finished PCB? I just built this and am not getting the desired results. Which resistor did you end up keeping? (sorry for jumping into this thread to ask questions, I'll be happy to make a new one).

I have posted a question in the troubleshooting section to not throw this thread off.

 

[debrad]

Here's a shot of my final assembly. Seems to work like all the other demo videos I have watched.

Did you note the comment from @aelling that says:

1N914/1N4148 work much better than 1N4001 for the two that go to the inputs on the 386. I tried some 1n34a also, and they were very very noisy, but not in a good way. The 1n4001 blocked too much signal and caused a lower output volume as well as a darker, less distorted, less prominent octaving effect even when doubled up in parallel to decrease fwd voltage drop.

 

[leadfoot]

Here's a shot of my final assembly. Seems to work like all the other demo videos I have watched.

Did you note the comment from @aelling that says:

1N914/1N4148 work much better than 1N4001 for the two that go to the inputs on the 386. I tried some 1n34a also, and they were very very noisy, but not in a good way. The 1n4001 blocked too much signal and caused a lower output volume as well as a darker, less distorted, less prominent octaving effect even when doubled up in parallel to decrease fwd voltage drop.

I did not see that note, thanks for bringing it to my attention. How sensitive to your guitar's volume control is it?

Thanks again!

 

[Feral Feline]

From the sounds of it, DeBrad, if you'd installed two 20k resistors, they'd be in parallel and you'd have 10k and used up those lazy good for nothing pesky 20k resistors.
Saves you a 10k resistor.

Those 10k resistors... I can never seem to keep enough of them!


Sorry, couldn't resist posting that.

 

[debrad]

@leadfoot, I used the 1N4148 instead of 1N34a and the pedal seems to function as it should