Tell me more ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.
up vote 0 down vote favorite

I need to build a device to measure the impedance in AC, at various frequency (100Hz - 100KHz), with the quadrupole method.

No, I have quite a good understanding of the principle behind the this kind of measurements. What I have some problem with is the construction of the setup i'm gonna need beside the 4-pin probe itself.

I guess I'm gonna need a AC current generator (right?) but what is necessary to acquire the data and be able to plot them both in a Bode representation (|Z| vs. freq and PhaseAngle vs. freq) and in Nyquist representation (-Im(Z) vs. Re(Z)).

This is really a little be outside my field of study so please, kindly elaborate :)

thx

share|improve this question
2  
as the question is mainly electronics related, you might also try this on electronics.stackexchange.com – JustJeff Dec 4 '10 at 15:07
also, you might say what accuracy and how many sample points you want. if just a dozen or so frequencies would suffice, you could do reasonably well with a 2-channel oscilloscope. if you're looking for thousands of high accuracy samples, you'll probably need a more sophisticated instrument. – JustJeff Dec 4 '10 at 15:10
1  
In my opinion this is off-topic here, it's a question about engineering and not physics. – Sklivvz♦ Dec 4 '10 at 15:52
I agree, this is off topic. It's not a physics question per se. (You even say you understand the principle, which is the only physics part about it.) – Noldorin Dec 10 '10 at 22:06

closed as off topic by Noldorin Dec 10 '10 at 22:07

Questions on Physics Stack Exchange are expected to relate to physics within the scope defined in the FAQ. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about closed questions here.

1 Answer

up vote 0 down vote

I am not familiar with impedance measurement using the quadrupole method. But with the information you have given I can make some guesses. The number of signal say the how many channels you need to measure. From the frequency band you said you are interested according to the sampling theorem, your oscilloscope sampling rate needs to be at least 200 KHz.

Computer sound cards have a digitizer of 44 KHz, if measuring up to 20 kHz would do and you need only 2 channels that should be enough. It can generate the 20 kHz signal too.

Otherwise usb oscilloscope, should do the job. Supposing that you have the signal generator as you talked. And I am supposing you can code your way up to make the whole acquisition using your computer. BTW, have any online reference to the quadrupole method you are talking about?

share|improve this answer

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