A card reader for a point-of-sale system that is configured to accept both magnetic strip-type and integrated circuit chip-type payment cards. An amorphous silicon film to be crystallized is doped with a metal element that accelerates crystallization, and then irradiated with laser light from the back side of a light-transmissive substrate. The bottom substrate has a bottom waveguide coil. The system determines the presence of a cardiovascular condition by applying a sliding scale rule to heart signal feature values. In preferred embodiments, a pitch frequency parameter is generated, and generation of the lower frequency-band signal includes generating continuous sine tones that are frequency shifted with the pitch frequency parameter.