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Dave's Circuits
Circuits designed by David Johnson, P.E.

Master Category List - Dave's Circuits
Last Updated on: Monday, April 21, 2008 04:18 AM


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.

Click on Drawing Below to view PDF version of Schematic

4mA to 20MA Current Loop Temperature Sensor designed by David A. Johnson, P.E. (July 4, 2000)

Current Loop Circuits
Master Schematic Category List - David A. Johnson, P.E.
 

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