0
$\begingroup$

I'm not sure if it's possible to do this, it's a maths problem rather than an electronic one, but the maths is beyond me so I was wondering if anyone might know.

I can't post images on maths.stack yet but this one is suitable:

https://i.stack.imgur.com/R8uWK.png

I have a RC low pass filter, simple resistor and capacitor in series, with a load resistance R2 in parallel with the capacitor who's impedance is roughly similar to that of C at the frequencies I can test at. I can measure the voltage across R2 at more than one frequency. Can I separate the C1 and R2 impedances mathematically from this to give me a value for these 2 components? The only component I know the value of is R1.

This page http://hyperphysics.phy-astr.gsu.edu/hbase/electric/filcap2.html gives a formula for Vout in terms of Vin, so in other words the voltage across C, but it does not consider a load resistance in parallel with C. Also, of course, it's not the whole solution, I believe it's a simultaneous equation I need if it's possible at all... Maybe not possible regardless.

Can anyone help? I'm well out of my depth in the maths department here. It's a real world problem for a sensor I am working on.

$\endgroup$
0
$\begingroup$

Question is answered in another question subsequent to this one:

Pythagorean question for vector calculation

The 2 amplitudes across R2 I can measure are d and e, R2 is a and b is Xc at the higher frequency and 2b is Xc at the lower frequency so you can get C by plugging in the frequencies into the equation for capacitive reactance.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.