《4.Microcontroller based LCR meter 》.pdf

M ~ E S S O R S AND MICROS~TEMS E L S E V I E R Microprocessors and Microsystems 20 (1996) 297-301 Technical application Microcontroller based LCR meter M.A. Atmanand, V. Jagadeesh Kumar Department of Electrical Engineering, Indian Institute of Technology,Madras 600 036,India Received 19 March 1995;revised 10May 1996 Abstract A microcontroller based scheme for LCR measurement is described. The unknown element (an inductor or a capacitor or a resistor) is measured employing a non conventional ac bridge. The element to be measured forms 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 parameters of L or C or R values are evaluated by the microcontroller and displayed in appropriate display fields. The scheme was implemented using an Inte18751 microcontroller. An overall accuracy of the order of +1.0% was achieved for the prototype with a 12-bit MDAC having an accuracy of 4-0.2%. Keywords: LCR measurement; Microcontroller-application; Quasi-balanced