How to read electrical diagrams

Written by kim lewis
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How to read electrical diagrams
Omegatron/, Dr. C

Electrical diagrams range from the very simple to the very complicated, but they all are based on the same elementary principles. To learn how to read them, it is necessary to have a basic understanding of the parts used in circuits, including their symbols, what they are used for, and how they are placed inside a circuit.

Skill level:
Moderately Challenging

Things you need

  • Circuit diagram
  • Introductory physics or electricity text
  • Handbook or data sheets on electrical components

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  1. 1

    Identify the most common symbols for electrical components. Resistors, capacitors, inductors, transistors, op-amps and diodes all have different symbols. Wires are represented as straight lines. They are treated as perfect conductors, so are considered to have zero resistance.

  2. 2

    Study the rules that are used to wire these components together. These are found in basic physics and electronics texts. They may also be found on the back of the component packages and on some data sheets. For example, the rules for connecting resistors are different from those of capacitors or inductors. An extremely important rule for components is that they may be wired in series or parallel. Points connected by the same wire are at the same potential and are electrically equivalent.

    How to read electrical diagrams
    Series and parallel circuits
  3. 3

    Memorise the symbols for voltage sources. A voltage source, such as a power supply or battery, may be symbolised in more than one way on a diagram. A direct current may come from a power supply or battery, while an alternating current comes from a power supply. A voltage source is polarised, which means that the way it is placed into a diagram is important. The anode is the + (plus) or positive side, and the cathode is the -- (minus) or negative side. The negative side is also referred to as the ground.

  4. 4

    Recognise the difference between polarised and non-polarised components. Like voltage sources, some components are also polarised. The way they are placed into the circuit with respect to the voltage source is important, while others are independent of their circuit direction. Some capacitors are polarised, while resistors are not.

  5. 5

    Learn the most common fundamental circuit combinations. These are certain electrical components that are always wired the same way using the same parts. Their role is to form mini-circuits that are used to perform certain tasks for a larger circuit. They may be viewed as building blocks. Examples of such are voltage dividers, diode clamping circuits and filters. Once you have mastered the basic analogue circuits, you may proceed to logic circuits.

Tips and warnings

  • To learn to read electrical diagrams of simple circuits, it is recommended that you buy educational electronics kits. They are inexpensive and typically include data sheets on the components used, as well as schematics for the project you are to build. They also detailed explanations on how the circuit works.
  • After you are comfortable with educational kits, you may wish to purchase educational project labs or the lower-end electrical trainers. They may also cover digital and advanced analogue circuits.

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