Abstract: An electronic device, e. g. a measuring transducer, has an interface circuit for communicating with and receiving power from a two-wire line, said interface circuit has a modulator connected to the two-wire line and responsive to an information signal for modulating the current in the two-wire line according to the information signal, and further has a controllable switching type DC-to-DC converter for extracting power for the electronic device from the two-wire line. To reduce energy losses, the DC-to-DC converter is designed to be controlled by said information signal and to perform the function of the modulation means.

Abstract: An electronic device, e. g. a measuring transducer, has an interface circuit for communicating with and receiving power from a two-wire line, said interface circuit has a modulator connected to the two-wire line and responsive to an information signal for modulating the current in the two-wire line according to the information signal, and further has a controllable switching type DC-to-DC converter for extracting power for the electronic device from the two-wire line. To reduce energy losses, the DC-to-DC converter is designed to be controlled by said information signal and to perform the function of the modulation means.

Abstract: A power decoupling circuit for a time-of-flight ranging or level measurement system coupled to a current loop. The level measurement system receives power from the current loop and includes a loop current regulator. The loop current regulator is responsive to signals from a controller for regulating the current in the loop to transmit level measurement data and other information. Power is also taken from the current loop to energize a transducer for generating pulses for performing level measurements. The power decoupling circuit comprises a feedback circuit and a step-up converter. The step-up converter provides charging current to an energy storage device for the transducer and may also generate a voltage gain. The feedback circuit controls the voltage drop across the loop current regulator to minimize losses on it and maximize power available for measurement.