Control knobs control devices that are controlled by operator input. These knobs are used to control and operate certain types of medical, scientific and industrial equipment, and they are also used in a number of home appliances and entertainment systems.
A control knob is most often a rotary control that provides input based on its degree of rotation. A control knob is a common component in any device's control system. It consists of a shaft that connects to the component of the device that produces the actual input, and a metal or plastic body that the operator grasps and controls.
Some control knobs are fitted with pointers or markings that indicate the device's current setting on a scale. A single device can have multiple control knobs for different functions. A clockwise rotation conventionally provides an increased input to the device, while a counterclockwise rotation decreases input, ultimately shutting down the device when the knob reaches a specific position or the point of origin of movement.
Control knobs are widely used in radios, satellites, avionics, transportation and telecommunications. A number of testing equipments are fitted with control knobs. Music and entertainment systems commonly use control knobs to adjust volume and to track radio stations.