Air core solenoids, possibly single layer and with significant spacing between turns, are often used to ensure low stray capacitance, as they are used as part of many sensors and instruments. The problem of the correct estimation of the stray capacitance is relevant both during design and to validate measurement results; the expected value is so low to be influenced by any stray capacitance of the external measurement instrument. A simplified method is proposed that does not perturb the stray capacitance of the solenoid under test; the method is based on resonance with an external capacitor and on the use of a linear regression technique.
In this paper a measurement system for determination of supercapacitor equivalent parameters is proposed. Specific properties of materials used for supercapacitor construction require some advanced tools and measurement procedures to be applied during tests. The measurement system allows to measure values of equivalent parameters by both the DC and AC method whilst keeping appropriate time criteria required by this type of devices. Furthermore, in this paper the most relevant properties and measurement capabilities of the proposed system are described as well as some exemplary values of the supercapacitor equivalent parameters measured experimentally are presented.