Design of a Low-Cost Microcontroller-Based Automatic Voltage Stabiliser for Small Businesses in Kano State

Background: Voltage fluctuations from the national grid pose significant risks to electronic equipment in small businesses across Nigeria, leading to frequent equipment damage and economic losses. Automatic voltage stabilisers provide protection but commercial units remain unaffordable for many small enterprises. Aim: This project designed and implemented a low-cost microcontroller-based automatic voltage stabiliser tailored for small business applications in Kano State, North West Nigeria. Methods: An ATmega328 microcontroller was programmed to sense input voltage via a step-down transformer and voltage divider, and to switch relay-controlled autotransformer taps to maintain output within a regulated range. Proteus software was used for circuit simulation. The prototype was bench-tested against simulated grid voltage variations between 170V and 260V. Results: The stabiliser regulated output voltage to 220V plus or minus 5V across the full input range tested. Response time to voltage transients averaged 18 milliseconds. Total component cost was approximately NGN 12,500, substantially below commercial equivalents. Conclusion: The designed stabiliser is technically effective and economically accessible. Its deployment can protect valuable electronic assets in small enterprises and reduce business disruption from grid instability. Further development should incorporate digital display interfaces and overload protection circuitry. Keywords: voltage stabiliser, microcontroller, ATmega328, small businesses, Kano.