A Simple Schematic Drawing Tutorial for Eagle

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This is my step-by-step guide to schematic drawing in Eagle. Let us say we find the circuit above interesting and want to build a real electronic circuit out of it to test in the real world. The first step is to recreate the schematics in Eagle.

Beginner’s guide to Eagle CAD

Create new project and schematic

We start our schematic drawing by creating a new project and a new schematic in Eagle. Open Eagle’s Control Panel and choose “File->New->Project” from the menu.

Add a new schematic to the project by selecting “File->New->Schematic” from the menu.You now have a blank schematic ready for drawing.

Add components

We continue by adding the four resistors to the schematic. Select “Edit->Add..” from the menu in the schematic editor. The “ADD” dialog box appears. Here we want to locate a resistor.

Write “resistor” in the search field and press Enter. You will probably find many alternatives. I chose a through-hole resistor called R-EU_0207/10 from the “resistor”-library. Choose one and press “Ok”.

Place the resistor on your schematic by left-clicking. Do this four times to get four resistors, then press ESC to return to the “ADD” dialog box.Continue to add the capacitors, transistors and LEDs in the same way.

Tips: To place the two transistor as mirrors to one another like I did, use the Mirror function “Edit->Mirror” in the menu.

Add component values

Now we’ll add values to the components. To do this choose “Edit->Value..” from the menu. Then click on the component you want to set value for. Enter the value and press Ok.

Add connection between components

To connect the components we need to add nets between them. Add nets by choosing “Draw->Net” from the menu.

Note: Never use “Wire”, always use “Nets”. The “Wire” does not always create the electrical connection you want.

Tips: If you want diagonal lines, choose the second “Wire bend” button from the toolbar.

Add power connection

If you want to create a practicable electronic circuit you will also need to connect power somehow. You can add two header pins for this. Search for “2 pin header” in the “ADD” dialog box to find a suitable part in the “con-molex” library. Add this and connect the two pins to the circuit.

Electrical Rule Check

Now we are ready to run an Electrical Rule Check (ERC) to see if there are any mistakes that need to be fixed.

Select “Tools->Erc” from the menu.

When I run it I get two warnings telling me that the LEDs don’t have any defined values. I know that this is not necessary for the LEDs so I click “Approve” on both of them.

Our schematic drawing is now complete.

Now, it’s time to create a PCB from the schematics.

Return from Schematic Drawing to Electronic Schematics

24 thoughts on “A Simple Schematic Drawing Tutorial for Eagle”

  1. Hi!
    Could you help me a little ?
    How do i know to choose the right component when I need one ?
    There are a lot !
    For example if need a common 12 v zener diode .
    Thanks !

    Reply

    • Hey! If you don’t have any other requirements, then one way is to just pick any 12V Zenerdiode with the preferred component package. Another way is to google for schematics similar to the one you are making and then see what they picked, maybe send them an email and ask why they chose that one..

      Cheers!
      Oyvind

      Reply
  4. Pingback: Tutorial: Building cool projects with MCUs (Part 4) | Bits & Pieces from the Embedded Design World

  8. Hey commentary ! I am thankful for the info – Does anyone know where I could possibly obtain a fillable NY DTF ET-117 version to work with ?

    Reply

  9. Hi there!

    I want to add a loudspeak to my circuit, but I can’t find that symbol in Eagle.

    What can I do to add it ?

    Thanks in advance !

    Reply

    • Think about how you will connect the speakers to the board. If you want to use a screw terminal for example, use that in eagle. Or just a 2-pin pin header if you want to holes to solder the wires into.

      Best,
      Oyvind

      Reply

    • Hi Heinrich,

      There aren’t different symbols for different capacitor types (except for polarized vs non-polarized). But electrolyte capacitors are usually (or maybe always) polarized, so just just a polaried one.

      Best,
      Oyvind

      Reply

  13. Downloaded the Eagle program for MAC and installed w/o difficulty. Following steps above..
    File->New->Project ….. OK
    File->New->Schematic….OK
    but
    Edit->Add brought up the dialog box OK
    typing in resistor in the search field resulted in “No Matches” so could not proceed further…

    Reply

    • You probably need to tell Eagle to “use” your libraries. In the Control Panel window if you right-click the library name there is an option “Use All”. If a library is used you will see a “green ball” after its name.

      Reply

  14. I don’t understand where the electricity from the capacitor goes(after it’s charged and I disconnect the battery, or am I supposed to do it?) it can’t go back to the led and it can’t go back to the resistor because it has a resistance of 47k oms, so how does it work and where does the electricity go? And if it electricity goed to the transistor, how? It cant flow from the negative side…

    Reply

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