Many electrical components have multiple versions. For example, there are several different types of transistors that are utilized in circuitry and each of them has its own function and, appropriately, each of them has its own schematic symbol with which it is associated. The most common schematic symbols are given below. All of the schematic symbols, however, are similar enough that it is readily apparent what they are, even if they represent a variation on the schematic symbols with which you are already familiar.
It’s important to look closely at the schematics and the symbols on them for any given electronic circuit. They oftentimes reveal more information about the circuit than what a novice might assume. In reality, the schematic symbols are designed to show the function of each of the components in a very abbreviated, compact way that is easy to read once you learn how. For instance, the symbol for a variable resistor is exactly the same as the symbol for a resistor, except it has an arrow on it which indicates that the resistance can be moved up or down. A light emitting diode has the same symbol as a regular diode, except it has two arrows projecting upward at a 45° angle from the diagram, indicating that it emits energy in the form of light. Understanding these subtleties can help you to get more out of schematic diagrams and more easily ascertain what’s involved with building any circuit that is represented thereby.