In article , Nick Gorham
wrote:


I just tried the experiment on a few caps I have to hand. The ones that
produces a sound when driven by a sig gen were a BC 368WKT 220nf,
Acotronics MKP 47nf and a 2.2uf ClarityCap SA. Ones that I tried that
didn't prduce any sound I could hear were from Solen and Mundorf.

Not sure what you refer to as a 'name brand' but I would think at least
the BC would fit that decsription.

Though as expected the level was very low, at the 2vRMS 5kHz from my sig
gen, it needed the cap to be against the ear, but it was clearly there.

What is the o/p impedance of your sig gen? 2.2microF at 5kHz is about 15
Ohms if my fingers just pressed the correct buttons on my hand calculator.
Implies a reactive level of over a Watt if you really were applying 5v rms.

If I understand the ClarityCap papers correctly, you'd need to find the
mechanical resonance of each cap to get a peak level of vibration. So 5k
might not give as large a response as some other frequency.

Slainte,

Jim

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