How to Read a Schematic

Reading a schematic is nothing more than knowing what the symbols mean, what the represented components do, and how they are annotated. There are actually hundreds of symbols, and even the most basic components have multiple variations, however I will show the most common components and explain what they do and how they can be recognized in schematics.

Symbol	Name	Description
	Resistor	A resistor, which is usually annotated on schematics by 'R', produces a voltage drop across its terminals as outlined in Ohm's Law (V = I/R). More can be learned about reading the colored bands on a resistor at the tutorial How to read Resistor Bands
	Capacitor	A capacitor, which is annotated on schematics by 'C', stores an electrical charge on two conductive plates seperated by an insulative material called a dielectric. The electrical charge on the two plates are equal in magnitude, but opposite in polarity. Capacitors have many uses on electrical circuits such as simply storing a charge or to differentiate between varying frequencies in filters.
	Ground	Ground is a term basically referring to the path to a zero voltage reference. In an alternating current situation, it is merely a fault line that leads back to electrodes connected to the Earth. In a direct current situation, it refers to the line going back to the negative terminal of the battery.
	DC Voltage Supply	A DC Voltage supply is an electrical supply, usually a battery, that provides direct current to the circuit.
	AC Voltage Supply	An AC Voltage supply is an electrical supply, usually from a wall socket or a bench supply, that provides alternating current to the circuit.
	Potentiometer / Variable Resistor / Trim	A Potentiometer is a resistor with an adjustable resistance.
	Diode	A diode is an electrical component that allows electricity to flow in only one direction. There are two other types of diodes, a Zener Diode which can be used to make sure a voltage level reaches a certain point before the circuit turns on, and a Light Emitting Diode (LED) which is usually denoted by a circle around the diode with an arrow. Diodes have two sides, the Anode and the Cathode. When voltage is presented on the Anode side, it is passed. When voltage is presented on the Cathode side, it is not passed unless the voltage overcomes the diode's breakdown voltage. Diodes are annotated on schematics by a 'D'
	Switch	A switch will allow or disallow voltage to pass depending on it's state (ON/OFF).
	Inductor	An inductor is an analog component made from a coil of wire wrapped around a core of air or some magnetic material. They are used mostly in filters. Inductors are annotated on a schematic by an 'L'
	Operational Amplifier (Op-Amp)	Op-amps have a multitude of uses, but basically they take an input an amplify it to an output. The amplification can be determined with a feedback resistor, and even inverted if desired.
	NPN Transistor	An NPN Transistor can basically be seen as two diodes with a shared anode. The uses of this type of transistor are numerous.
	Integrated Circuit (IC)	An IC is a miniature circuit with a specific purpose. Functions, pinout, min/max operating conditions, etc... is described in each IC's data sheet, which can easily be found online. IC's on a schematic are usually annotated by a 'U'