On Tue, 12 Jul 2022 08:17:33 -0800 Bob kb8tq via time-nuts <[email protected]> wrote:
> Hi > > If you have any ceramic capacitors in the mix, they are often > microphonic. The X7R versions are typically the best “high C” types. > NPO’s normally are completely non-microphonic. Other non-ceramic caps > should be ok, but who knows. > _________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe send an email to [email protected] Actually X7Rs are quite bad. Z5Us, also. Both are piezoelectric. I don't use them any more except for power supply bypass in non-critical supplies. As a part of a precision temperature controller project (microKelvin), I needed to select capacitors for low microphonics. The ceramic types mentioned above are the worst offenders; but several other types (certain film types included) show some microphonic activity. Best to evaluate every capacitor type by charging to 10 Volts, or so, AC coupling to an audio amplifier/sensitive oscilloscope/or other and tapping to see if noise is produced. Stephen Menasian _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe send an email to [email protected]
