How To Design A PCB – Part 2

So you have completed Part 1 of How To Design A PCB.  Now on to part 2 where we will finish designing a very simple LED circuit.

Once you have your first component on your schematic it is time to wire up your whole circuit. Start by searching for a resistor. Again go to the parts library.




and type in ‘resistor’ in the Search field at the bottom of the popup window.  You will notice a huge number of available parts.  Please find a 1206 part.  0402, 0603, 0805, 1206 reference the size of SMD components and applies to resistors, capacitors and more.




Click OK and now place the resistor symbol on your schematic.  You can rotate this component just by clicking your RIGHT mouse button.




Next we will find an LED.   Again there are a huge number of options for an LED in the library. To simplify things type into the Search field ‘1206’ instead of ‘led’.  Find a part that says LED1206 from the list of options.  If you are using Eagle CAD version 7.6 you should see a SparkFun-LED library.  Pick the LED1206 component and place this into your schematic. Your schematic should look something like this.




We will now wire up this circuit which will complete your schematic.   Now click on the WIRE BUTTON on the left menu bar.




We will now connect all of these components.  This part is a little tricky.  Click on the right end of the resistor.   This will create a light green wire that you can now pull to your next component.




Please click on the anode side (top) of the LED component. Notice how the wire turns from a light green color to a dark green color.  Once you have done this you should see the diagram above.




You will also notice that as you drag around your mouse the EAGLE CAD software is expecting you to connect the next component.  We want to stop this by clicking on the round STOP BUTTON at the top of the schematic window.




We will now wire up the rest of this circuit.  Again, click the WIRE BUTTON on the left side of the schematic window and click on the bottom side of the LED component and then click on the bottom of the BATTERY component.  You will notice during this process that the wire lines do not allows follow a way we want it to go.  Try clicking the RIGHT mouse button.  This changes the orientation of how the wire is being drawn by the software.

To help learn the user controls, please create a U shape connection that connects the cathode side (bottom) of the LED to the negative terminal (bottom) of the battery. While in the WIRE mode, you will need to click on a location underneath the battery terminal like the diagram below before you connect to the negative terminal of the BATTERY component.

Because the user interface can be difficult to use you will make mistakes.  You can always UNDO and start over by going to Edit -> Undo.




Now connect up the positive terminal (top) of the battery to the resistor and we are done. Again. You need to click the STOP BUTTON and then the WIRE BUTTON each time you start connecting a wire from a new location.   This is what you should see.




Congratulations! You’ve just finished wiring up your first PCB schematic.  Now go make something.


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