Description

Four-to-twenty milliampere current loops are commonly used in the process control industry. They takeadvantage of the fact that a remote amplifier can be powered by the same 4-20 mA current that it controlsas its output signal thus using a single pair of wires for signal and power. Circuits for making 4-20 mAtransmitters are found in the LM10 LM163 and LH0045 data sheets.