Build Questions: "The Low Down" (chopped OC-2) by DC6FX

[elenore19]

I'll try to make this quick as to not waste your time.
Build Doc:
https://drive.google.com/open?id=0B7QeV_7r70dTNE4xSHo4cHY3eEE
Board:
https://www.oshpark.com/shared_projects/RywmoHxm
Questions:
Are C15 and C16 supposed to be non-polar? Seems like super high values (110uF and 220uF) for non-polar to me. But I have a ton to learn, so I assume I'm wrong.
In which case--(noob question)-Would it be possible to substitute Polar caps in place of these?

Also does anyone know if the build doc "mistakes" are still in the boards you get from oshpark? I'm thinking they were fixed, but just curious.

Thanks for the help guys.

[mjg]

I'm building this one at the moment too, and there is an 'errata' document that addresses your questions - the contents are as follows:

---
Outdated bits are as follows:

You can ignore the error corrections in the build guide; I fixed and updated the PCBs. There are some mods I suggested in the build doc. After playing around with them, they aren't anything to really write home about, but the filter pot is a neat little addition, if you are so inclined.
... and responses to my newbie questions:

Q: Is V1 the LED?

A: There isn't a status LED on this board. It will have to be added offboard.  V1 is the DC input. One pad goes to ground, the other hooks up to the +9V. I don't remember which one is which on the top of my head, but you can use a digital multimeter to see which one is continuous with the other ground pad.



Q: What are ES, OS, US and MO?

A: Those other pins are for the wires for the various mods. I mention the mods in the build doc, but I don't think they add much to the pedal's usefulness. I would ignore them.



Q: Where is the 9VDC input?

A: V1 is the DC input. One pad goes to ground, the other hooks up to the +9V. I don't remember which one is which on the top of my head, but you can use a digital multimeter to see which one is continuous with the other ground pad.

Q: C15 (100u) and C16 (220u) are shown in the schematic and on the PCB layout as film caps, but ...they'd be HUUUGE!   ... I see you used electrolytic caps for C15 and C16, ... does orientation matter ...?
A: Yes, C15 and C16 have a certain orientation. The negative legs of the caps would go to the pads that are attached to ground. C16's ground pad is the lower pad, and C15's is the pad closest to the IC. You might want to double check with a multimeter.

[elenore19]

Thank you! This was a huge help.
I got it up and running, but it's super quiet and has a little background fuzziness.
Any ideas?

[mjg]

Hmm, I don't know about the noise, I've not finished mine and I'm waiting on a parts order before I'll have it running. 

[diablochris6]

It's been a while since I looked at this circuit. Thanks for sharing my insight that I wouldn't have remembered today, mjg!

I'm not sure about the background fuzz, but it seems that this circuit would do best to have a gain boost circuit at the beginning.