coupling device for transmission of metverdessignaler from a metgivare via a tvatradskrets to a receiver

摘要

A circuit arrangement for transmitting signals from a measuring transducer via a two-wire circuit to a receiver which, in turn, via the same two-wire circuit supplies power for operating the transducer. The circuit arrangement comprises a voltage controller, a current switch a current generator, and a power-storage capacitor connected at the transducer end of the two-wire line. The voltage controller supplies the voltage from the two-wire circuit to the measuring transducer as a regulated voltage. Parallel to this the current switch charges the power storage capacitor in the rhythm of the frequency-analog measurement signal. Via the current generator, e.g. an ohmic resistor, the capacitor also receives the voltage input from the measuring transducer. The operating current of the measuring transducer is thus provided partly by the voltage controller and partly by the current generator or resistor. The ratio of these currents determines the modulation depth of the current pulses on the two-wire circuit.