Rotary potentiometers are three-terminal devices: the two outer terminals connect to the ends of the resistive track, and the centre (wiper) terminal carries the variable output. For a simple volume control, connect the signal to the first outer terminal, ground to the second outer terminal, and take the output from the wiper. For a voltage divider (sensor) application, connect a fixed voltage across the outer terminals and read the wiper voltage. Always check the datasheet for the correct taper (linear or audio) and resistance value before wiring. For long cable runs, use shielded cable and ground the shield at one end to reduce noise. With wiper at the middle of travel, the output should read approximately half of the supply voltage. If the output jumps or reads incorrectly, check the ground connection and ensure the wiper is not left open circuit.