A microcontroller-based quasi-balanced bridge for the measurement of L, C and R

Author

Atmanand, M.A. ; Kumar, V. Jagadeesh ; Murti, Vempati G K

Author_Institution

Dept. of Electr. Eng., Indian Inst. of Technol., Madras, India

Volume

45

Issue

3

fYear

1996

fDate

6/1/1996 12:00:00 AM

Firstpage

757

Lastpage

761

Abstract

A microcontroller-based quasi-balanced bridge for the measurement of parameters of an inductor or a capacitor is described. The unknown element (inductor or capacitor) in series with a resistor forms one-half of an ac bridge, while a multiplying digital-to-analog converter (MDAC) serves as the other half. The bridge is brought into two independent quasi-balanced conditions in succession by the microcontroller through the MDAC. The parameters of the unknown element are shown to be functions of the settings of the MDAC at the two quasi balanced conditions. The relevant expressions for these parameters are evaluated by the microcontroller and the results displayed in appropriate display fields. The proposed scheme was implemented using an Intel 8751 microcontroller and tested. The readings obtained on the prototype were compared to those obtained with a commercial LCR meter. Employing an MDAC of basic accuracy ±0.2%, over the frequency range of 100-1000 Hz, an overall uncertainty in measurement of ±0.7% for the prototype was achieved

Keywords

bridge circuits; bridge instruments; capacitance measurement; computerised instrumentation; electric impedance measurement; inductance measurement; microcontrollers; 100 to 1000 Hz; AC bridge; Intel 8751 microcontroller; LCR measurement; capacitor; inductor; multiplying digital-to-analog converter; quasi-balanced bridge; Bridges; Capacitors; Digital-analog conversion; Displays; Frequency; Inductors; Microcontrollers; Prototypes; Resistors; Testing;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.494595

Filename

494595