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New Method for Determining Time Constant of Resistors



Yicheng Wang, Dean G. Jarrett, Andrew D. Koffman, Stephan Schlamminger


We report a new method for determining the time constant of ac resistors with values around 10 kΩ, using a digital impedance bridge for comparison of two nominally equal resistors. The method involves adding a probing capacitor in parallel to one of the resistors to induce a quadratic frequency dependence in the real component of the admittance ratio between the two resistors. The magnitude of this quadratic effect is proportional to the self capacitance of the unperturbed resistor, enabling us to determine its value and the associated time constant with an estimated standard uncertainty (k = 1) of 0.02 pF and 0.2 ns, respectively.
Review of Scientific Instruments


ac resistor, time constant, phase angle, digital bridge, impedance standard.


Wang, Y. , Jarrett, D. , Koffman, A. and Schlamminger, S. (2023), New Method for Determining Time Constant of Resistors, Review of Scientific Instruments, [online],, (Accessed May 18, 2024)


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Created March 21, 2023, Updated June 23, 2023