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Systems diagrams and schematic diagrams are specifically for electronic and mechanical systems.

System diagrams

Designing certain products, eg electrical products, may require a different technique known as a systems approach. This logical approach is particularly useful in electronics where there is an input, process and output, as each stage has to perform a specific function before moving on to the next step.

Block diagrams can be written, usually in boxes, with the headings input, process, and output. When planning how a circuit will function, these headings are then used to plan what the input, process and output could be.

In the case of designing an electric piano keyboard, the input is pressing the key, the process is generating the correct music note and the output is sound through the speaker. Systems approach should not be confused with schematic diagrams, which show how an electronic system should be connected together.

Systems approach flowcharts

A systems approach flowchart relates specifically to the design of a process. They can be used for programming a circuit so that a programmable chip can process an input and then turn on an output. Different shapes in a flowchart represent different types of operation, and these shapes have the same meaning worldwide.

Quality assurance decisions can also be added during the design process to ensure that problems are picked up and fixed within the system, eg a decision stage checking the dimensions of a part that has been manufactured.

Schematic diagrams

Schematic diagrams use symbols to show the layout of electrical or mechanical systems. A circuit diagram is a schematic that shows how components are connected up.

Schematics can also be used in repair manuals. Symbols are simplified and look nothing like the physical components themselves, and the schematic diagram never makes a reference to the position of components on a circuit board.

The schematic diagram describes the points of electrical connection only, and these are shown as dots. The symbols are not drawn to scale so don’t have dimension information, and they can be spaced out to avoid looking jumbled or overly complex.

Producing a schematic drawing on a computer is far neater than drawing it by hand, with computer programs available to quickly create accurate and neat schematics that can be easily shared with others.