Current Loop Circuits TEMPERATURE SENSOR WITH 4 TO
20mA CURRENT LOOP
I designed a circuit similar to this one years ago to accurately measure the air
temperature inside a building 1000s of feet from a control room. The circuit
uses a very robust current loop method. It uses a highly accurate
semiconductor temperature sensor and an equally accurate voltage reference. The
circuit includes a diode bridge, so it is polarity independent. By using the
component values indicated, the circuit should not require calibration. It
has a range from –40F to +120F and an accuracy of +/- one degree F. |