Compact and Scalable Voltage-Controlled Resistors: Programmable Optically Variable Resistors for Enhanced Circuit Precision

This paper presents a novel Programmable Optically Variable Resistor (POVR) that provides a wide, continuously adjustable resistance range using an LED-LDR (Light Emitting Diode-Light Dependent Resistor) pair, controlled by varying the LED’s forward bias voltage. The POVR addresses limitations of fixed-value resistors, offering greater precision, compactness, and cost-effectiveness over digital potentiometers and motorized rheostats. Experimental results confirm its wide resistance range, low parasitic capacitance, and scalability. Thermal stability and temperature dependence were also investigated, highlighting the need for heat-sinking. The POVR is ideal for applications like transistor biasing and RC circuits, with future improvements aimed at enhancing stability and integrating predictive models.