Electronics Club - Circuit Symbols Advertiser Discounts and Offers. Circuit symbols are used in circuit diagrams showing how a circuit is connected together. The actual layout of the components is usually quite different from the circuit diagram. To build a circuit you need a different diagram showing the layout of the parts on breadboard (for temporary circuits), stripboard or printed circuit board. Electronic Components and Circuit diagram Symbols wwwrycircuit›BasicJan 22, 2017These are represents Power supply and bias details in circuit diagram. Symbol with + and – indicates DC (direct current) source and symbol with sin wave indicates AC (alternating current) source. Crystal and Resonators. Crystal and Resonators are important to produce clock pulse for microcontrollers and other circuit.