Virtual capacitance meter based on impedance modulus measurement

The capacitance can be calculated from the impedance modulus value of the object under test. It is possible, if a two-terminal network is represented by a series connection of a resistor and a capacitor and the reactance of the capacitor is considerably greater than the resistance (e.g. in a low-loss capacitor). In this case the error of the approximation can be omitted. A virtual realization of such meter has been presented in the paper. This one shows the idea of the signal processing in the quasi-balanced circuit. Quasi-balanced circuits are the AC circuits designated for impedance component measurements. Similar as the balanced circuits, the quasi-balanced circuits have a special status called a quasi-balance status. This is usually a phase shift between two selected signals of the circuits. The circuit finly 1 Liltfis driven to the quasi-balance status by controlling of me variable element and then the value of the measuredfiuic vaiuc ui me iiicasuu mpedance component can be calculated using the adjusted um var: on ich has been controlled by a software programmed : alue or the variable element. Ihe meter has been built with ie application of the data acquisition card USB N1-6009, been controlled bv a so environmen ai.