Schematic Diagrammes

A schematic acts as a map of a circuit, showing all of the individual components and how they interconnect with one another. According to one popular dictionary, the term schematic means of or relating to a scheme; diagrammatic. Therefore, you can call any drawing that depicts a scheme (electronic, physiological, geographic, or whatever) a schematic diagram.

One of the most common types of schematic is a road map for use in motor vehicles. The map might show all the navigable paths of travel inside a town, within a state or province, or across multiple states or provinces. Like a schematic of an electronic circuit, a road map shows all the landmarks relevant to a geographic region.

In electronics, a schematic allows a technician to extrapolate the components and interconnections when testing, troubleshooting, and repairing a small circuit, a large device, or a huge system.

Suppose that you want to drive your truck from one place to another. Your road map shows all the landmarks between these two locations. By comparison, a schematic shows all the components between any two points in an electronic circuit. But both diagrams indicate more than mere points. You need to know more than which towns lie between two fixed locations to get an idea of the overall nature of the region. You could write down the names of the various towns or landmarks along a chosen route, but such a list couldn't take the place of a good road map. From an electronics standpoint, you could do the same thing by compiling a list of the components in certain circuit, such as:

• Two 120-ohm resistors
• One 1000-ohm resistor
• One PNP transistor
• Two 0.47-microfarad capacitors
• 90 centimeters of hookup wire
• One 6-volt lantern battery
• One switch with a built-in circuit breaker

This list tells you the ingredients of the circuit, but nothing in a functional sense. You know all the components necessary to build the circuit, but you don't know what it will do when you put it together! In fact, you might combine these components in several different ways to make circuits that do different things.

A schematic must not only show all the components in a circuit, but also how these components work with each other. A road map connects towns and other points of interest with lines that represent streets and highways. A line that indicates a secondary road differs from a line that represents a four-lane highway. With practice, you can learn to tell at a glance which sorts of lines indicate which types of roads.

In electronics, a schematic uses a solid line to indicate a plain electrical conductor such as a wire or foil run; other types of lines (or sets of lines) represent cables, logical pathways, shielding enclosures, and wireless links. Whenever you draw an interconnecting line or set of lines, you portray some relationship between the connected components.