What’s the Deal with Pedalpcb Film Cap Sizing?

[Caldo71]

I feel like I should know this already, 2 years into this obsession…

On most pedalpcb build documentation—or even if not, it can be inferred by the size of the component outline silkscreened onto the actual PCB—there is indication of whether one should use a 7mm x 2mm film cap, or the bigger 7mm x 5mm kind.

What is not USUALLY in the notes column (sometimes I HAVE seen it but not usually) is WHY that size?

Am I supposed to infer from the larger cap size suggestions that those need caps with higher voltage handling? Tighter tolerances? Something else?

If it’s the first thing (voltage) what is the negative effect if one uses a wee cap instead? How will that manifest in terms of issues with tone or performance?

Help me understand! Thanks!

 

[Bricksnbeatles]

The bigger ones are usually more accessible when it comes to stuff over 470nF

I think if there’s room to spare, Robert goes with the bigger footprint just so either can be used. It can be harder finding larger values in 2x7mm form, so they seem to be a last resort for when there’s no space to allow for 5x7mm caps

 

[jimilee]

Sometimes he likes to be symmetrical.

The bigger ones are usually more accessible when it comes to stuff over 470nF

I think if there’s room to spare, Robert goes with the bigger footprint just so either can be used. It can be harder finding larger values in 2x7mm form, so they seem to be a last resort for when there’s no space to allow for 5x7mm caps

sometimes, @Robert likes to be symmetrical.

 

[Caldo71]

sometimes, @Robert likes to be symmetrical.

SOMETIMES? I’d say that’s his mission in life!

I didn’t think about though. The symmetry obsession and the “if there’s room why not do it?” Factor.

This was the one that was making me scratch my head today…

…I was wondering why one would need a big ol’ honkin’ cap in such a low value.

 

[Robert]

Purely cosmetic in that case. You don't have to follow the dimensions listed in the build docs either, they're just given as a guideline for the folks who have no idea what sizes they're looking for.

It doesn't hurt anything if the component doesn't fill the outline or if it overlaps the outline... you can install them on the back, laying down, hovering above other components, overlapping and shoving the neighbor to the side, etc.... the listed dimensions just state what should fit without any issues.

 

[Robert]

Sometimes he likes to be symmetrical.

sometimes, @Robert likes to be symmetrical.

I hope the symmetry in your reply was intentional.

 

[Caldo71]

Here’s an even more extravagant flaunting…



…how dare you, sir? How dare you?

 

[Robert]

I take it you haven't come across one of these tricksters yet?

 

[Laundryroom David]

I take it you haven't come across one of these tricksters yet?

View attachment 46237

But does it go to ground?

 

[szukalski]

I'm still waiting on the MichaelW special edition board where every electrolytic is comically oversize.

 

[Laundryroom David]

I'm still waiting on the MichaelW special edition board where every electrolytic is comically oversize.

I have some comically large .100 uF film caps that I’m planning to use as a dedication to him.

 

[Laundryroom David]

I take it you haven't come across one of these tricksters yet?

View attachment 46237

All joking aside, I am SO relieved to know I don’t have to keep looking for a PCB598 resistor.

 

[Caldo71]

I feel I’ve suddenly fallen into an inside joke hole.

 

[iamjackslackof]

All joking aside, I am SO relieved to know I don’t have to keep looking for a PCB598 resistor.

I have some new-in-box NOS germanium black plate red dot ones I'll let go... for a price

 

[Caldo71]

…so those photos I posted earlier are from a Cetus build that I literally just finished and tried out a half hour ago…man, that thing sounds pretty f$&in’ good!

I’m hijacking my own thread here with a hard seguay into a different topic, but @Robert I was wondering if you could tell me a bit about how this thing makes the crunchy happen?

It’s the first distortion pedal I’ve built where there are no visible three leg transistors or LEDs but with three ICs on there instead, so I’m curious how those kinda designs gain stage, and what role all those little diodes at different voltages play.

 

[music6000]

I'm still waiting on the MichaelW special edition board where every electrolytic is comically oversize.

Like this one, 44 Gallon Drums might Fit!!!

 

[Barry]

…so those photos I posted earlier are from a Cetus build that I literally just finished and tried out a half hour ago…man, that thing sounds pretty f$&in’ good!

I’m hijacking my own thread here with a hard seguay into a different topic, but @Robert I was wondering if you could tell me a bit about how this thing makes the crunchy happen?

It’s the first distortion pedal I’ve built where there are no visible three leg transistors or LEDs but with three ICs on there instead, so I’m curious how those kinda designs gain stage, and what role all those little diodes at different voltages play.

I don't know, but it's got the strangest diode configuration I've seen in the feedback loops!

 

[Robert]

That's asymmetrical zener diode clipping, the stages clip at different (and higher than normal) thresholds.

 

[Feral Feline]

SOMETIMES? I’d say that’s his mission in life!

I didn’t think about though. The symmetry obsession and the “if there’s room why not do it?” Factor.

This was the one that was making me scratch my head today…
View attachment 46234
…I was wondering why one would need a big ol’ honkin’ cap in such a low value.

Cap 10n is installed upside down
Upside down installed is the 10n cap.


OCD
DCO


ADHD
DHDA

All joking aside, I am SO relieved to know I don’t have to keep looking for a PCB598 resistor.

You have some spare Virgils then?
Then some spare Virgils have you?

 

[Barry]

That's asymmetrical zener diode clipping, the stages clip at different (and higher than normal) thresholds.

Zeners, that makes sense now, very clever!