Block Diagram - Learn about Block Diagrams, See Examples Symbols Used in Block Diagrams. When block diagrams are used in electrical engineering, the arrows connecting components represent the direction of signal flow through the system. Whatever any specific block represents should be written on the inside of that block. A block diagram can also be drawn in increasing detail if analysis requires it. Block diagram - Wikipedia In electrical engineering, a design will often begin as a very high level block diagram, becoming more and more detailed block diagrams as the design progresses, finally ending in block diagrams detailed enough that each individual block can be easily implemented (at which point the block diagram is also a schematic diagram).