Moving-Coil Meter with Separate Supply using INA193
The digital meters is lack of accuracy and resolution in comparison to drawing information upon a measurement’s rate of change or tracking a reading’s trend. To solve this problem, we should use analog moving-coil meters. Here is the schematic diagram of analog moving-coil meters :
This circuit uses 8-inch moving coil meter with a measuring current range from 0 to 100mA. This circuit also uses INA193 that amplifies the 100-mV full scale input by a gain factor of 20 V/V, full-scale output is 2 V. Besides that, OPA344 also used in this circuit to possesses rail-to-rail outputs and inputs. The maximum output voltage swing of the OPA344 is limited to 5 V because this circuit operates from a single 5-V supply.
The value of Rs1 is depends on application and is a compromise between maximum permissible voltage drop in the measurement line and small-signal accuracy. For providing better accuracy at lower currents, the values of Rs1 must be high, and for minimizing voltage loss in supply line, Rs1 must be low. [Source: Texas Instruments Application Note]