Construction of a Digital Capacitance Meter Using a 555 Timer Circuit for Laboratory Use at Kaduna State University

Background: Capacitance measurement is a routine laboratory task in electronics courses, yet commercial capacitance meters remain expensive and unavailable in many Nigerian university laboratories. A low-cost, student-built alternative can bridge this resource gap. Aim: This project constructed and calibrated a digital capacitance meter based on the 555 timer IC for laboratory use at Kaduna State University, North West Nigeria. Methods: The 555 timer was configured in astable mode, producing a frequency inversely proportional to the unknown capacitance. An AT89C51 microcontroller computed and displayed the capacitance value on an LCD after frequency measurement. Calibration was performed against NIST-traceable standard capacitors from 10 pF to 1000 microfarads. Results: The meter measured capacitance within plus or minus 3.5% of standard values across the tested range. Minimum measurable capacitance was 15 pF. Component cost was NGN 3,200, representing a saving of over 90% compared with commercial equivalents. Conclusion: The constructed digital capacitance meter is accurate, affordable, and suitable for undergraduate electronics laboratory use. The study recommends institutional adoption and extension of the range by implementing frequency prescaling for very small capacitances. Keywords: capacitance meter, 555 timer, digital measurement, Kaduna State University, electronics laboratory.