Electronics > PCB/EDA/CAD

Noisey (as in audio freq) PCB

<< < (2/2)

amspire:

--- Quote from: itdontgo on October 31, 2011, 01:36:02 pm ---It's the sound of the signal!  It's normally something like a 6-10kHz wave.  Sine-ish!

--- End quote ---

Then definitely look at the EEVBlog discussion that alm mentioned on the piezo effect in ceramic capacitors.

Replacing the capacitor with a different kind of capacitor will very likely cure the problem.  Even a different brand might solve it.

itdontgo:
Yeah that's what it is.  It's hard to see which one is making the noise but it must be one the HPF/LPF caps as they must have reasonable current flowing through them (being low Z).

I think the procurement for 1000 boards has already been done but never mind I'll market it as a 'feature'!   ;)

ejeffrey:
Any high-k ceramic capacitor in an audio frequency signal path can cause this problem.  It is very likely that the problem is not one bad capacitor, but several.  One thing to keep in mind is that the reverse happens, too.  Vibrations will be picked up as signal by the capacitors.

ivan747:
What is high K?
And, is low Z low impedance?

Thanks!

slateraptor:

--- Quote from: ivan747 on November 07, 2011, 10:45:02 pm ---What is high K?

--- End quote ---

Solid-state process jargon. You might be more familiar with the symbol epsilon_r, or relative permittivity with respect to permittivity of free-space.

http://en.wikipedia.org/wiki/High-k_dielectric for more info.



--- Quote from: ivan747 on November 07, 2011, 10:45:02 pm ---And, is low Z low impedance?

--- End quote ---

Yup.

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod