[Boatanchors] Disc caps vs paper caps

[Ian Wilson]

I have noticed enormous amounts of drift in Colpitts-type crystal
oscillators using some
types of ceramic capacitors in the loop. This resulted in significant chirp
on each key down.

I don't know whether this is due to some form of self-heating, but the
capacitance changes
were so large that I can readily imagine that if you scaled the values up,
and used these
capacitors in an audio coupling network, that you should be able to detect
the nonlinear
change of time constant with input readily enough using both normal ears or
some sort
of audio spectrum analyzer.

73, ian K3IMW