Browsing by Author "NANGALAMA RICHARD"

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    DESIGN AND DEVELOPMENT OF HUMAN TOUCH SENSOR
    (BUSITEMA UNIVERSITY, 2026-08-26) NANGALAMA RICHARD
    This project focused on the design and development of a simple, low‑cost human touch sensor system that uses body heat as the detection method. Unlike expensive commercial sensors or complex microcontroller-based devices, this system is built around an NTC thermistor, which changes its electrical resistance when warmed by a finger. The thermistor is connected to the gate of a MOSFET, which acts as an electronic switch. A variable resistor is placed between the gate and ground, allowing the user to adjust the sensitivity of the system to suit different people or environmental conditions. When a warm finger touches the thermistor, its resistance drops, raising the voltage at the MOSFET gate past the threshold set by the variable resistor. The MOSFET then turns on, completing the circuit for a standard LED and a 5V buzzer. A protection diode is connected in reverse parallel across the buzzer to absorb voltage spikes that could otherwise damage the MOSFET. The entire circuit is powered by a common 9V battery, and no microcontroller or programming is required, keeping the design affordable and easy to understand for students. All components were selected because they are readily available in local electronics markets such as Kikuubo in Kampala, Uganda. The prototype was first assembled on a breadboard for testing and later transferred to a perfboard by soldering to make the connections permanent. Testing involved five different users, each performing ten touches under normal indoor conditions, for a total of 50 touches. The system achieved an overall accuracy of 94%, responding instantly to warm fingers. The few failures occurred when fingers were very cold like after washing with cold water but warming the hands or increasing the sensitivity solved the issue. The variable resistor proved effective, allowing the system to work with different finger sizes and temperatures. False triggers from non‑heat sources such as plastic objects, wood, or moving air were rare and only occurred at the highest sensitivity setting. The system also ran continuously for one hour without overheating or failing. Overall, the project successfully met its objectives, demonstrating that a reliable touch‑activated alert can be built from affordable, locally sourced parts. Potential applications include a touch‑activated buzzer at a reception desk, a doorbell alternative for small businesses, an interactive teaching tool for physics laboratories, or an assistive device for people with limited mobility. The design is open for further improvements such as adding a larger touch surface, weatherproofing the enclosure, or adding visual indicators for the sensitivity setting.