Circuit Symbol of Diodes

Diodes
Component Circuit Symbol Function of Component
Diode diode symbol A device which only allows current to flow in one direction.
LED Light Emitting Diode LED symbol A transducer which converts electrical energy to light.
Zener Diode zener diode symbol A special diode which is used to maintain a fixed voltage across its terminals.
Photodiode photodiode symbol A light-sensitive diode.

Circuit Symbol of capacitors

Capacitors
ComponentCircuit SymbolFunction of Component
Capacitorcapacitor symbolA capacitor stores electric charge. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but pass AC signals.
Capacitor, polarisedpolarised capacitor symbolA capacitor stores electric charge. This type must be connected the correct way round. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but pass AC signals.
VariableCapacitorvariable capacitor symbolA variable capacitor is used in a radio tuner.
Trimmer Capacitortrimmer capacitor symbolThis type of variable capacitor (a trimmer) is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment.