A miniature eddy current transducer developed earlier by the authors is used for nondestructive testing of metal-insulator transitions. This article describes the well-known eddy current testing method based on the analysis of electrical conductivity distribution across the surface and within the test material. The design of eddy current sensor, principles of operation, and its connection to a personal computer via sound card interface are presented along with main technical parameters, types of transducer, and coils. The paper contains a brief overview of sensor application area and an algorithm of sensor controlling software. Results obtained from eddy current testing of metal-insulator transitions show the dependence of sensor response on thickness of layered media with and without conductive substrate (copper substrate is used). A technique of layered materials development is described, and industrial significance of such materials is shown. The sensor response is proved to be dependant of various composite materials, such as aluminum-polyethylene and aluminum-paper. Sensor settings for testing of composite materials mentioned above are also provided.