ZWEIDRAHT-FERNMESSEINRICHTUNG

摘要

A DC powered transmitter, eg for fluid flow rate, temperature or pressure, gives a dc signal, in accordance with the sensed variable, supplied over a two-wire line W1, W2 to a receiver 13 in which a DC voltage supply is connected to the line through load resistor 12. Across resistor 12 is an output signal in a predetermined current range for operating an indicator. The same line supplies operating power to the power input terminals of the transmitter through a switching-type step down power regulator 17 that gives constant power under high voltage-low current as well as under low voltage-high current conditions, thereby making more power available to the transmitter and increasing its load drive capability. <IMAGE>