Traditional potentiometers are designed with a wiper that slides across the resister to signal the amount of voltage needed. The pot is connected by three wires: a calibrated voltage input, an output signal and a ground. The ground wire is attached on one side of resister and two voltage wires are on the other. As the wiper turns either to the ground wire or toward the voltage wires, the amount of voltage is adjusted accordingly. Movement toward the ground wire indicates less voltage. For audio volume control, turning toward ground would reduce the volume. Turning the knob toward the voltage wire results in higher volume.
Engineers often seek alternatives to pots so that the number of applications can be increased. Traditional pots tend degrade rapidly under high use and easily give out if infected with contaminants such as dirt, sand or other grime. An alternative that would be immune to both degradation from use and exposure to contaminants is preferred. Additionally, because traditional pots can break easily, alternatives that can withstand heavy vibration are desirable.
Non-contact magnetic encoders use the same three wire transmission system as do traditional potentiometers, but they are encased so that the device is useable in outdoor and underwater applications. Non-contact magnetic encoders are manufactured as solid-state devices without moving parts to prevent degradation resulting from shock or overuse.
Non-contact rotary sensors are based around the Hall-effect sensing module, which allows the device to be controlled without electrical contact with the operating dial. When the shaft or dial is turned, the sensing module detects the movement and transmits the signals necessary. Thus, no wear and tear can destroy the device. The rotary sensor is encased to prevent contamination. This alternative to potentiometers is used in cars and motorcycles.