How to Read Circuit Diagrams

May 23, 2024


Circuit diagrams are important tools in the field of electronics, providing a visual representation of circuits. These diagrams are crucial for designing, troubleshooting, and understanding how electronic components are interconnected. Whether you are a beginner or an experienced engineer, mastering the skill of reading circuit diagrams is the foundation for successfully engaging in electronic work. In this guide, we will explore the basics of circuit diagrams, common symbols, and how to effectively interpret them.



What is a circuit diagram?

A circuit diagram, also known as a schematic, is a graphical representation of a circuit. It uses standardized symbols to represent components and displays their connection methods through lines representing wires. Circuit diagrams are used to design and document electrical systems and have significant value in both educational and professional environments.



Basic components and symbols

To read circuit diagrams, you need to be familiar with common symbols used to represent various electronic components. Here are some of the most commonly used symbols:


1. Resistor

  • Symbol: A zigzag line (USA) or a rectangle (IEC).
  • Function: Restrict the current flow in the circuit.


2. Capacitors

  • Symbol: Two parallel lines (one straight and one curved for polarizing capacitors).
  • Function: Store and release electrical energy.


3. Inductor

  • Symbol: A series of rings or a curled line.
  • Function: Store energy in the magnetic field when current passes through.


4. Diode

  • Symbol: A triangle pointing towards a line (indicating the direction of current flow).
  • Function: Only allows unidirectional current flow.


5. Transistor

  • Symbol: Three terminals are marked as base (B), collector (C), and emitter (E) for BJT; The gate (G), drain (D), and source (S) are used for FET.
  • Function: Amplify or switch electronic signals.


6. Integrated Circuit (IC)

  • Symbol: A rectangle with pin numbers or markings.
  • Function: Execute multiple functions based on internal circuits.


7. Switch

  • Symbol: An interrupt in a line that can be connected or disconnected.
  • Function: Control the current flow by opening or closing the circuit.


8. Power Source

  • Symbol: A long and short line (battery) or a circle with positive (+) and negative (-) symbols.
  • Function: Provide necessary voltage and current for the circuit.


Understanding connections and layouts

1. Wires and connections

  • The lines represent the wires connecting the components.
  • There is a point at the intersection of two lines indicating a connection.
  • Lines without dots crossing indicate that the wires are not connected.


2. Series and parallel circuits

  • Series connection: The components are connected end-to-end, and current flows through each component.
  • Parallel connection: Components are connected in parallel at the same two points, with the same voltage on each component.


3. Grounding and power symbols

  • Grounding: Refers to a line with three horizontal lines below.
  • Power supply: represented as a positive (+) and negative (-) sign or a line with two parallel lines.


Reading Circuit Diagrams Step-by-Step

1. Identifying components

Firstly, identify all symbols used in the diagram. If there is a component list, please refer to that list.


2. Understanding current flow

Determine the current flow through various components from the power supply. Pay attention to the direction of the diode and the direction of the polarizing capacitor.


3. Analyze sub circuits

Decompose complex graphs into smaller sub circuits. Understand each part separately and then see how they interconnect.


4. Tracking signal path

Track the signal path from input to output. This is particularly important in amplifiers and signal processing circuits.


5. Finding Key Points

Identify key points such as voltage dividers, feedback loops, and grounding points.


Practical skills for beginners

1. Start Simple

Start with simple circuits such as LED scintillators or basic amplifiers. Gradually shift towards more complex graphs.


2. Using reference materials

Keep the symbol reference guide at hand. Online resources and textbooks are very helpful.


3. Regular practice

Regular practice is essential. Attempt to redraw the circuit diagram to enhance understanding.


4. Simulate Circuitsa

Use circuit simulation software to test and understand the working principle of the circuit. Tools such as LTspice, Multisim, or online emulators are very suitable.


Interlinking and Resources

For more in-depth information on electronic components and circuits, you can explore these pages on our DRex Electronics blog:


External Resources

For additional learning, you might find these external resources helpful:



Reading circuit diagrams is a fundamental skill in electronics that enables you to effectively design, troubleshoot, and understand electronic circuits. By becoming familiar with common symbols, understanding circuit layouts, and regularly practicing, you can master this important skill. Whether you aspire to become an engineer or an electronics enthusiast, mastering the ability to read circuit diagrams will enhance your ability to innovate and handle complex electronic systems. To learn more about electronic components and their applications, please visit our DRex Electronics website.