Does anybody have any idea of typical values for capacitance and inductance of potentiometers? I have been looking at datasheets for various potentiometers from at least six different brands, and there is never any info on this or any related parameter. I am primarily interested in ordinary, panel-type potentiometers, not trimmers (although such info is welcome too). I suspect C and L wouldn't change much depending on resistance value, and maybe not much with resistive material either. The physical design will matter of course, although I suspect most pots to be so similar in design that they do not have very large variations.
I did a couple quick measurements on a 10K Allen Bradley panel mount pot, starting with a vector impedance meter. The internal strays for the resistance element are negligible if you intend to connect the pot using wires or traces. Expect a few degrees of capacitive phase shift at 1MHz- my measurements were contaminated by the very short connecting wires, but that's my guesstimate when comparing with a 1/4W 10K MF resistor. There was no connection to the shell.
The real issue is capacitance to the metal shell of the pot, which is invariably grounded to the panel. On a 1615 bridge, the capacitance between one end of the element and the shell was 17.8pF with a D of 0.14 at 1kHz, series model. There was no wiper connection. Worth thinking about if one is using high values.
The real issue is capacitance to the metal shell of the pot, which is invariably grounded to the panel. On a 1615 bridge, the capacitance between one end of the element and the shell was 17.8pF with a D of 0.14 at 1kHz, series model. There was no wiper connection. Worth thinking about if one is using high values.
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