capacitor vibration noise

[Kinshoro]

I was wondering if it is possible that ceramic capacitors can have a piezo-electric effect and effect the signals on a circuit especially audio or microphone signals. If they do...... at what frequency would those effects be seen..........?????

 

[keith1200rs]

It seems that they can be microphonic:

https://en.wikipedia.org/wiki/Microphonic

I gues it's not surprising - if you compress them the capacitance must change. In fact I seem to remember a project many years ago where I used to work where they were trying to measure the pressure in hydraulics using a normal capacitor which was squashed by the hydraulic pressure.

Keith.

 

[betwixt]

I've witnessed it in commercial products too. A PLL inside a telephone product that went out of lock if you hit the keys too hard! It took some persuading to get the designer to even consider that might bet the problem but on analysis, that's exactly what was happening.

Brian.

 

[Kinshoro]

Okay so what type of capacitors won't resonate at these frequencies........ I heard film capacitors or X2Y capacitors are better for low noise applications compared to the ceramic capacitors...... are film capacitors available for any value of capacitance?