Abstract: A transmitting and receiving system including, a transponder always maintains a transmission function even if circuit constants of circuit elements are deviated or such circuit constants are shifted in association with temperature changes. The transponder includes a transponder coil electromagnetically coupled to an antenna coil through which a response signal is transmitted, a resonance capacitor, a main modulation circuit including a first modulation capacitor, and a supplemental modulation circuit including a second modulation capacitor whose static capacitance value is different from that of the first modulation capacitor. A response signal is transmitted in changing an impedance of a transmitting and receiving portion by the main modulation circuit when a question signal is received and by the supplemental modulation circuit when a correction command signal is received.

Abstract: In a logging device for registering the frequency of manually entered operator control functions for an electrical device, the frequency of entered operator control functions are selectively counted. Consequently, it can be established with which frequency the individual operator control functions are activated. The logging device may be connected separately to the electrical device, for example a car radio, via a bus or be integrated into the electrical device. The operating characteristics of a certain operator can be stored individually for the operator and can be output automatically when this operator enters an identification code. This simplifies the operating of an electrical device with high operating convenience. It is also advantageous that, for example in the motor vehicle, the driver is distracted less from the traffic situation when operating the car radio.