[sdiy] Are power electrolytics microphonic?

[harry]

Charge them up... scope them on AC and tap them... look for the frequency

of any ringing from the mechanical excitement...

Then run them above 105C... they'll die soon

H^) harry (who is also working on a cap decision... Big electrolytics or
Big
film caps...?.)

Toby Paddock wrote:

> Semi-OT:
> I'm doing vibration testing on some fairly large (but not real large)
> electrolytic caps. And I was wondering if I could find the resonant
> frequency of the guts by charging it up thru a high resistance and
> looking for an AC signal when the stuff starts flexing inside.
> (That sentence was way too long.)
>
> Seems like if the layers flex and move, it might change the
> capacitance. So with a constant charge, that would vary
> the voltage.
>
> They are like 450 WVDC and I don't know the C value. The
> aluminum can is about 1.25 inch dia. by 3.5 inches long.
>
> Ideas? Opinions? Advice? Point and laugh?
>
> Thanks,
>  - -- -  Toby Paddock