Pork Barrel clicking

[jkokura]

Hey there everyone. I'm getting clicking when my pork Barrel is in bypass. There's also occasionally a bit of pop when I stomp the switch. I'm thinking I need a resistor on the 3PDT...

I didn't use the Madbean switch layout, I used my usual bypass ala Beavis Audio... Maybe that's it?

Jacob

[madbean]

This is actually the second report I've gotten recently about clock noise with the PB. I'm surprised because neither of the two builds I've done (one on etched and one on the fabbed prototype) had this problem. As far as the switch wiring: as long as you have it set where the fx input is bypassed I think it's fine. Using shielded wire on the ins and outs may help. Also, take a look a how your wires are laid out. You'll want to make sure that they are not running in parallel to each other.

Couple questions: where did you get your 3101/3007 and what kind of PS are you testing it with?

[jkokura]

I'm using a Boss PSA 9VDC, and I got my chips from Smallbear.

It's weird, cause my circuit's input is grounded when it's in bypass, which usually fixes everything. I had an issue at first with having my power leaking to ground, but I found the solder bridge and it works now. I only get ticking on bypass. The trim pot doesn't affect anything.

I don't have any shielded wire right now. I thought maybe a pulldown resistor, but maybe I'm misunderstanding what that is.

Jacob

[madbean]

Hmm. Well you should definitely have some play with the trimpot. That might be a separate issue.

Here's something you can try for the clicking: add a 100pF ceramic cap on the trace side between pins 1 and 5 of the MN3101. This is added filtering for the Vd rail, and the promixity to the chip may reduce or eliminate the click.

Also, try a battery. Those Boss PSUs can definitely cause noise in the supply...mine are not regulated at all and put out close to 13v.

[maysink]

Also, take a look a how your wires are laid out. You'll want to make sure that they are not running in parallel to each other.

Brian: can you expand on this? The parallel bit? Also, slightly related, is it helpful at all to use shielded wire for the +DCv connection?

[madbean]

The gist of it is that you don't want signal wires running in parallel to DC supply wires, and probably not with themsleves either. Most of the time we use insulated wire which helps provide some protection, but unless you are using shielded wire on everything, it's best to try to keep some separation between them. You can cross them perpendicularly, but long parallel runs can result in noise, and even oscillation in high gain circuits.

I only mention this as a general rule of thumb. I break it all the time. But, when you run into noise or oscillation issues, this is one area where the problem can exist.

[jkokura]

I have my input and output wires running right next to each other and the ground to the switch. I bunch them up and zip tied them together. I'll try running the output by itself on the other side of the enclosure and see if that fixes it. If not... I might have some extra Lava Cable around, but I'd rather not use it.

Jacob

[madbean]

K. I do recommend you try the 100pF cap, too. Other values are okay.

[jkokura]

Well, I got it to work. You know what it was? None of the solutions above fixed the problem, not the power, not the input and output wires being in parallel, not even Brian's excellent cap suggestion.

I'll post the solution later tonight, but if someone wants to stab at it...

Jacob

[jkokura]

Ok, so no guessers...

The rate pot wiring was really close to the output jack, but as soon as I pushed the wires the clicking changed. I was able to move them to a spot where there was no ticking whatsoever.

The rate pot wires! Strange but true.

Jacob

[madbean]

Great! So, lead dress can definitely have an effect here. I'm glad you got it sorted out.

[B_of_H]

this is good to know, mine has some clicking noise as well.