FIELD: data transfer circuits. SUBSTANCE: data transfer circuit has station and response circuit designed for card with built-in microprocessor. Station has primary coil with signal generator for building up variable carrier-frequency magnetic field and amplitude demodulator. Response circuit has secondary coil and amplitude detector for producing impact onto secondary-coil load by modulating variable carrier-frequency magnetic field by information signal. Response circuit also has phase modulator for producing impact onto electrical characteristics of secondary coil; amplitude modulator and/or phase modulator are specially designed to afford control over either of them by minimum one signal modulated by information signal. EFFECT: enhanced operating reliability. 11 cl, 6 dwg
