Electronics Components: Integrated Circuits in Schematic Diagrams
In an electronic schematic diagram, an integrated circuit is usually represented simply as a rectangle with circuit connections placed conveniently around the rectangle without regard for the physical positioning of the pins. Each pin connection is labeled.
Notice that the pins in this schematic diagram aren’t in the same order as they are in the actual DIP package. Thus, when you build this circuit, you have to adjust the wiring layout to accommodate the pin arrangement of the DIP package.
Notice also that not all of the pins on an Integrated Circuit are always used. Unused pins are usually omitted from the schematic diagram. For example, pin 5 is not used in the circuit, so it is omitted from the schematic.
Some integrated circuits contain two or more independent circuits that share a common power supply, sort of like conjoined twins. For example, the 556 dual timer chip contains two complete 555 timer circuits within a single 14-pin package. When chips like this are used in a circuit, the schematic diagram may show them separately.
Please don’t worry about the details of this circuit. The intent here isn’t to explain how these circuits work, but only to show you how the integrated circuits are depicted in the schematic diagrams.