Posted on Jul 15, 2012 5918
This circuit uses a Hall-effect sensor, consisting of an IC that resides in a small gap in a flux-collector torrid, to measure de current in the range of 0 to 40 A. You wrap the current-carrying wire through the toroid; the Hall voltage VH is then linearly proportional to current I. The current drain from VB is less than 30mA.
To monitor an automobile alternator"s output current, for example, connect the car battery between the circuit"s VB terminal and ground, and wrap one turn of wire through the toroid. Or, you could wrap 10 turns-if they fit-to measure 1 A full scale. When I~ 0 V current sensor CS/s VH output equals one-half of its 10 V bias voltage. Because regulators !C1 and IC2 provide a bipolar bias voltage, Vy and VoUT are zero when I is zero; you can then adjust the output gain and offset to scale VoUT at 1 V per 10 A.