[time-nuts] GC-1000 Clock Cap Choice?

[Chuck Harris]

I have found that such high dielectric constant capacitors have other
problems in some circuits.  While the capacitance value is dropping,
as much as 50% when you apply voltage, their physical volume is
changing.  They behave as piezoelectric transducers.

I have used them inappropriately, and found them singing loudly.  If
that were to happen in a switching regulator, I would think the ultrasonic
vibrations could do damage to the capacitor, the PCB, or the solder joints.

-Chuck Harris

Poul-Henning Kamp wrote:
> In message<4D336A19.40709 at freenet.de>, "Dr. Frank Stellmach" writes:
>
>> High cap value Ceramics are available since years, [...]
>
> Can you clarify one thing for me: When I studied datasheets for these
> it looked like they drop 50% of their capacitance at a DC voltage
> of 10-20V.
>
> Doesn't that make them a so-so bargain for power supply bulk capacitance ?
>