A Beginner’s Guide to Circuit Diagrams

A first look at a circuit diagram may be confusing, but if you can read a subway map, you can read schematics. The purpose is the same: getting from point A to point B. Literally, a circuit is the path that allows electricity to flow. If you know what to look for, it’ll become second nature. While at first you’ll just be reading them, eventually you will start creating your own. This guide will show you a few of the common symbols that you are sure to see in your future electrical engineering career.

The Language of Circuitry

First, let’s look at some of terms that you will need to know:

  • Voltage: Measured in volts (V), voltage is the ‘pressure’ or ‘force’ of electricity. This is generally supplied by a battery (such as a 9V battery) or “mains electricity,” the outlets in your house operate at 120V. Outlets in other countries operate at a different voltage, which is why you need a converter when traveling.
  • Current: Current is the flow of electricity, or more specifically, the flow of electrons. It is measured in Amperes (Amps), and can only flow when a voltage supply is connected.
  • Resistance: Measured in Ohms (R or Ω), resistance defines how easily electrons can flow through a material. Materials such as gold or copper, are called conductors, as they easily allow flow of movement (low resistance). Plastic, wood, and air are examples of insulators, inhibiting the movement of electrons (high resistance).
  • DC (Direct Current). DC is a continuous flow of current in one direction. DC can flow not just through conductors, but semi-conductors, insulators, and even a vacuum.
  • AC (Alternating Current). In AC, the flow of current periodically alternates between two directions, often forming a sine wave. The frequency of AC is measured in Hertz (Hz), and is typically 60 Hz for electricity in residential and business purposes.

The Schematics

Now’s the fun stuff. Completing an electrical engineering degree and then getting a job in the field means you will see a lot a lot a lot of these schematics. It’s important to understand exactly what is going on with these. While they can (and will) get very complex, these are just a few of the common graphics to get your footing on.

Starting to make sense? These are the basics and may even seem obvious or intuitive to you, such as the wires and if they are connected. Whenever you determine your specific field of electrical engineering, you may see more complex diagrams and symbols. You’ll learn also that different countries use different symbols. For example, of the two symbols for resistors above, the first one is used in the U.S., while the second is used in Europe. You will also learn about the various symbols used for switches, other power supplies, inductors, meters, lamps, LEDs, transistors, antennas, and much more.

As you consider what electrical engineering program is right for you, it’s important to keep the basics of the field in mind. As mentioned earlier, these symbols and schematics will be all over the place. The sooner you familiarize yourself with the verbal and pictorial languages of engineering, the more prepared you will be in your quest for a degree. If you want to see more 1) it means you’re on the right path, and 2) consider this table as your digital cheat sheet.