[Hallicrafters] Piesoelectric effect case in point.

[Glen Zook]

There may not be any way that a ceramic disc capacitor can become a transducer, but I have, on very rare occasions, heard audio coming from a disc ceramic capacitor that has been used for coupling in an audio circuit.  Replacing the capacitor, usually with a "poly" type, has cured this "problem".

I have also run into an occasional problem where, when "tapped", a disc ceramic capacitor did act microphonic and introduced the "sound" into the audio chain.  Have run into this on both transmitters and receivers.

Probably, replacing with another ceramic disc might have solved the problem.  One that did not have whatever "defect" which caused it to act like a speaker.  However, when I do experience this I just replace the disc ceramic capacitor with a different type and go on to the next problem.

Glen, K9STH

Website:  http://k9sth.com


--- On Sun, 1/2/11, rbethman <rbethman at comcast.net> wrote:

Having just researched ceramic capacitor construction, I don't see ANY way that these would have the ability to become a piezo transducer, OR having anything to do with these old boatanchors.
 
You "may" want to do a bit of research also.  They also manufacture "dipped ceramic" capacitors.