I'm interested in learn why some capacitors make noise (under what conditions?). I'm asking that because i fixed a monitor some day and after it was making some fine (acute) noise, and someone told me it was because of some capacitor.

 

Hi,

It might be that a ceramic capacitor was "singing". They sometimes exhibit piezoelectric characteristics. If tapped, they are microphonic, and generate a small electical output. Yours may be responding to a waveform and generating a mechanical motion - the noise - as a result.

 

Thanks for the answer. That makes sense.