Setting Device

an element of an automatic control system that establishes a given value of the quantity being controlled or determines a program according to which a controlled quantity changes. Setting devices may be mechanical, pneumatic, electrical, or electronic depending on the physical nature of the system and on the nature of its signals. Calibrated springs, weights, levels, electric resistances, and standard current or voltage sources may be used as setting de-vices for the establishment of the values for quantities being controlled. The float-type regulator installed in the carburetor of a motor-vehicle engine to regulate the fuel flow is an example of such a setting device. To set a program according to which a regulated quantity changes, the simplest automatic control systems use shaped cams, templates, and rheostats; computers are used in more complex systems.