Current Research Bulletin

Accurate measurement of inductance and capacitance is essential in electronic circuit design, component characterization, instrumentation, and educational laboratories. However, commercially available Inductance-Capacitance-Resistance (LCR) meters with high measurement accuracy are often prohibitively expensive for many institutions of higher learning and laboratories in resource-constrained environments. This study presents the design, implementation, and experimental evaluation of a low-cost PIC16F628A-based digital Inductance-Capacitance (LC) meter employing the parallel resonance principle for inductance and capacitance measurement. The developed system determines unknown component values by measuring the resonant frequency of a resonant circuit using the microcontroller's 16-bit timer/counter, while a software-assisted three-step calibration algorithm compensates for reference component tolerances and environmental variations to improve measurement accuracy and repeatability. The hardware architecture integrates a constant-current excitation circuit, an LM311 comparator-based signal conditioning stage, a Liquid Crystal Display (LCD), and a Recommended Standard 232 (RS-232) communication interface for real-time display, data logging, and computer-based analysis. The prototype was experimentally evaluated using standard inductors (2.2–150 mH) and capacitors (2.2 nF–47 µF) with known nominal values. Experimental results showed that all tested components were measured within their specified tolerance limits, with mean absolute percentage errors of 1.8% for inductance measurements and 0.8% for capacitance measurements. Repeatability tests yielded standard deviations below 0.2% of the measured values, demonstrating stable and consistent measurement performance. The locally designed and constructed instrument combines a simple hardware architecture with software-assisted calibration to provide reliable inductance and capacitance measurements at low implementation cost. Consequently, it offers a practical and affordable alternative to commercial LCR meters for educational laboratories, electronics workshops, research environments, and field-service applications.

Digital LC meter, parallel resonance, PIC16F628A, embedded instrumentation, low-cost measurement system

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