Programmable Optically Variable Resistors: Long-Range, Compact and Scalable Voltage Controlled Resistors
Sneha Ray, Abhigyan Das, Tanushree Saha, Kanta Bhattacheryya, Angsuman Sarkar, Palash Das and Aritra Acharyya
This paper introduces a novel Programmable Optically Variable Resistor (POVR) designed to address the limitations of fixed-value resistors in achieving precise resistance in electronic circuits. The POVR utilizes an optically coupled LED-LDR (Light Emitting Diode-Light Dependent Resistor) pair to provide a wide, continuously adjustable resistance range, controlled by varying the LED’s forward bias voltage. This innovative approach ensures minimized deviations between desired and actual circuit outputs, offering advantages over traditional digital potentiometers and motorized rheostats in terms of precision, compactness, and cost effectiveness.The POVR’s resistance can be tailored by selecting different LED colours, adjusting the spacer material, and modifying input voltage, providing flexibility for various circuit applications. Experimental measurements demonstrate the POVR’s wide resistance range, low parasitic capacitance, and scalability. The study also investigates the thermal stability and temperature dependence of the POVR, with results highlighting the need for heat-sinking mechanisms for stable operation at room temperature. Compared to existing solutions, the POVR offers superior performance with significantly lower error rates. The device is particularly suited for applications requiring high precision and continuous resistance variation, such as transistor biasing and RC filter circuits. Future improvements will focus on enhancing thermal stability, expanding its applications, and incorporating predictive models for automated resistance control.
Keywords: Light emitting diodes, light dependent resistors, resistance, resistance-voltage characteristics, programmable optically variable resistor, transistor biasing.