MICROCONTROLLER BASED LCR METER

A microcontroller based scheme for LCR measurement is described. The u nknown element (an inductor or a capacitor or a resistor) is measured employing a non conventional ac bridge. The element to be measured for ms one arm (side) of the bridge and the second (series) arm is made up of a simple resistor. A Multiplier type Digital to Analog Converter ( MDAC), controlled by a microcontroller, serves as the other two arms. The microcontroller, after obtaining quadrature condition between the bridge output and one of the designated bridge voltages, acquires the current through and voltage across the series connected resistor. With these values and the value of digital input to the MDAC, the paramete rs of L or C or R values are evaluated by the microcontroller and disp layed in appropriate display fields. The scheme was implemented using an Intel 8751 microcontroller. An overall accuracy of the order of +/- 1.0% was achieved for the prototype with a 12-bit MDAC having an accur acy of +/-0.2%.