Many applications related to the control of motors and other types of two-way DC loads require the monitoring of the current flowing through these loads. The circuit shown in figure 1, suggested by Intersil (www.intersil.com) in its Application Note 1298 uses an EL8170 integrated circuit.
This circuit can monitor currents up to 2 A in both directions, when the output voltage will vary from 0 V (for -2 A) to +4.0 V (for +2 A). The very low-value branch resistor practically does not "steal" any power from the fed load. In this application the amplifier has a gain 100 and is powered by a 15 voltage source.
Changing the value of Rs can modify the range of measured currents. Note, however, that the maximum voltage between X1 and X2 must be 5 V.
