Gas leakages and smoke from early-stage fires are major safety threats in domestic, commercial and small-scale industrial environments. This risk is more severe in low-resource settings where commercial detectors may be unaffordable, difficult to maintain, or dependent on communication infrastructure that is not continuously available. This study presents the design and implementation of a low-cost gas and smoke detector intended for domestic and small-scale industrial safety. The system was developed using an Arduino-class microcontroller, an MQ-series gas/smoke sensor, local visual and audible alarms, a regulated 5 V power supply, and an optional display/telemetry interface. Three design alternatives were compared: cellular GSM alerting, standalone local audio-visual alerting, and IoT cloud-based alerting. The local audio-visual architecture was selected for the core prototype because it provides immediate response, low cost, high maintainability and independence from Wi-Fi or cellular network failures. The detector logic uses analog signal acquisition, voltage conversion, sensor-resistance estimation, digital thresholding and alarm actuation. A threshold of 600 ADC counts, equivalent to approximately 2.93 V on a 10-bit 5 V analog-to-digital converter, was used as the alarm decision level. Power-budget analysis indicated an estimated maximum continuous current demand of about 210 mA, making a 5 V, 1 A adapter sufficient while allowing short-duration battery backup. The prototype is estimated to cost less than USD 25 per unit, indicating potential for affordable deployment in households, workshops and small enterprises. Further work should include certified calibration using known gas concentrations, longer-term drift testing, multi-sensor redundancy and compliance assessment against relevant safety standards.
Emmanuel Anosisye Mwangomo (Mon,) studied this question.