Schematic drawing

(graphic arts) A presentation of the element-by-element relationship of all parts of a system. Also known as schematic drawing;

Concise, graphical symbolism whereby the engineer communicates to others the functional relationship of the parts in a component and, in turn, of the components in a system. The symbols do not attempt to describe in complete detail the characteristics or physical form of the elements, but they do suggest the functional form which the ensemble of elements will take in satisfying the functional requirements of the component. They are different from a block diagram in that schematics describe more specifically the physical process by which the functional specifications of a block diagram are satisfied.

An electrical schematic is a functional schematic which defines the interrelationship of the electrical elements in a circuit, equipment, or system. The symbols describing the electrical elements are stylized, simplified, and standardized to the point of universal acceptance (Fig. 1).

Simple transistorized code practice oscillator, using standard symbols. (Adapted from J. Markus, Sourcebook of Electronic Circuits, McGraw-Hill, 1968)

In a mechanical schematic, the graphical descriptions of elements of a mechanical system are more complex and more intimately interrelated than the symbolism of an electrical system and so the graphical characterizations are not nearly as well standardized or simplified (Fig. 2). However, a mechanical schematic illustrates such features as components, acceleration, velocity, position force sensing, and viscous damping devices. See also Drafting; Engineering drawing.

Mechanical schematic of the depth-control mechanism of a torpedo.