Sensor. - Here is Circuit Schematic Current Sensor Module For Microcontrollers w/ ACS712 like in figure 1 below. The circuit design is centered around a fully integrated, linear current sensor ACS712 from Allegro. The sensor (in SOIC8 package) consists of a precise, low-offset, linear Hall-effect sensor circuit with a copper conduction path located near the surface of the die.
|Figure 1. Schematic Current Sensor Module For Microcontrollers w/ ACS712|
The circuit schematic above show us that it is a microcontroller-compatible current sensor module you can build yourself, using an inexpensive 8-pin chip as an ‘active shunt’ for measuring ac/dc current levels upto 20 Amperes. First of all, note that the circuit as it stands is only really intended to show how a basic current sensor module can be built and act as a stimulus for further improvement.
The internal resistance of this conductive path is 1.2 mΩ typical, providing low power loss. The do-it-yourself module described here is a simple carrier for Allegro’s ±20A ACS712 linear current sensor. This 5VDC operated little module accepts a bidirectional current input, and outputs an analog voltage (66 mV/A) centered at 2.5 V (Vcc/2) with a typical error of less than 1.5%.
It is better to rig up the whole circuit using smd components on a dedicated printed circuit board. The PCB should made with 2-oz copper to reduce unnecessary power loss in the circuit board. Photograph of a readymade ACS712 current sensor module is included here as an example.
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