Mohamed Kamal Posted January 17 Share Posted January 17 what is the difference between using 1M ohm or another resistor in the resistor options in the impedance analysis does the value affect the accuracy or smth ? Link to comment Share on other sites More sharing options...
0 JColvin Posted January 17 Share Posted January 17 Yes. Impedance Analyzers in general rely on having a known resistance/impedance to compare the unknown impedance with, specifically to compare the voltage drop and phase difference of a signal between the known and unknown loads. Using a known impedance value that is close to the unknown impedance value, ideally within an order of magnitude, will give you more accurate results as the differences will not be (effectively) attenuated. The catch of course is that you known which known resistance to use when attempting to determine the value of the unknown impedance because it's, well, unknown. WaveForms in combination with the Impedance Analyzer adapter helps to account for this by comparing initial measurements between the on-board known resistances and the unknown impedance and quickly cycling through the different known resistors to give users the closest match to provide the most accurate results (due to least amount of difference between the known and unknown values). Let me know if you have any questions. Thanks, JColvin Link to comment Share on other sites More sharing options...
0 Mohamed Kamal Posted February 3 Author Share Posted February 3 (edited) so, this means that I will get a right reading in all cases but the most accurate one cannot be determined without knowing the proper resistor? I also want an explanation for the parameters, for example: what is the series capacitance and parallel capacitance. and how to get the overall capacitance? Edited February 4 by Mohamed Kamal Link to comment Share on other sites More sharing options...
0 JColvin Posted February 6 Share Posted February 6 Hi @Mohamed Kamal, The formulas for the various calculations of the Impedance Analyzer are provided in the WaveForms Help tab: Rs and Xs have some additional clarification in this Forum thread here: As for how to get the 'overall capacitance', both series and parallel models provide the overall capacitance; which model you "should" choose depends on what kind of measurement you are making. This Application Note provides a good overview and addresses this type of question in its FAQ: https://assets.testequity.com/te1/Documents/pdf/series-parallel-impedance-parameters-an.pdf. Let me know if you have any questions. Thanks, JColvin Link to comment Share on other sites More sharing options...
0 Mohamed Kamal Posted February 25 Author Share Posted February 25 i tried to calculate the Rs depending on equations but i didn't get the same results as taken from discovery . but the impedance magnitude is fine i did the calculations and it matched the results Link to comment Share on other sites More sharing options...
0 attila Posted February 26 Share Posted February 26 Hi @Mohamed Kamal The calculations in the application take in account the probe(s) impedance. Link to comment Share on other sites More sharing options...
Question
Mohamed Kamal
what is the difference between using 1M ohm or another resistor in the resistor options in the impedance analysis
does the value affect the accuracy or smth ?
Link to comment
Share on other sites
5 answers to this question
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now