PCB Circuit Design using EAGLE

When I started my first electronics project, A Variable Power Supply, the first thing I did was to draw the schematic diagram of the circuit on pen and paper. Problem arise when I do not know how transfer it on a PCB for etching. That's when I turned to Google to help me. I found this open-source software for PCB designing called EAGLE.

The name EAGLE is an acronym, which stands for Easily Applicable Graphical Layout Editor. This award winning software offers user friendly, powerful and affordable solutions for PCB design, including Schematic Capture, Board Layout and Autorouter. User Language Programs enable features such as simulation and 3D-visualization.
EAGLE is perfect for students and professionals because of its user-friendly interface and lots of features for your simple to hands-down complicated circuit designs. Because of the many things you can do with EAGLE I will not  just focus on the tools and the steps that I used in making my VPS and how I did it.

(For those who want to print the Variable power supply circuit and schematic click the download link below)

First download EAGLE (Windows/ Mac/ Linux) on their site, and Install. It takes up only a small space.

After installing it click on the icon, at the EAGLE Control Panel Right Click on Project > New Project - a new project folder will appear (you can rename the folder if you like).

Now right click on the folder and go to "New" > "Schematic". This will create a schematic file and an EAGLE "Schematic" window will appear.

To be able to place components to the work area we need to select the component libraries to be used. To do that click on "Library > Use..." and a window will appear. Locate the component library that you'll use. Usually the component library will be similar to the name of the component.

On my version of EAGLE I can only open a single library at a time so its a bit exhausting, but I think newer versions will be able to open more than one.

Anyway, once you're done we can now add components on the work area and start making your schematic diagram! On the command buttons at the left side on the window click on the"Add" button, then locate the element in the search bar at the bottom left. Hit the escape button when you're done.

Other tools that I used on making my Schematic are the

Move tool for moving the components within the work area,

Selection tool for defining a group,

Delete tool for deleting components,

Rotate tool for rotating, and

the Net tool for making the connections.

The Name tool is used to define the name of the element

and the Value tool to indicate the value.

After the connections are finished, you'll have something like this

This one's the schematic for the power supply that I made for my project. Another thing that I liked about EAGLE is once you're done with the schematic all of the elements placed will be transferred to the board for arranging and etching. To design the board click on the "Board" button, this will take you to the board window. Clicking this button again will take you back into the Schematic window - just in case you need to change or add something.

The board window is connected to your schematic so the components that you've placed will also appear in the board diagram not in terms of its schematic symbol, but as a drawing of the component itself. Also since what your working on the board is your schematic diagram, any changes on it will affect the board.

With the use of the move tool and rotate tool arrange the circuit to your liking. Make sure that no yellow line will intersect so that the next step will be easier.

Another tool that I would like to introduce is the "Rats nest" tool.

What it basically does is to further simplify the connections of your circuit, making it much more easier to arrange and design. I had problems of properly placing the wires so that they won't overlap, this tool really helped me on doing that.

After lots of moving, rotating and 'ratsnest'-ing you'll have something like this.

the last step in making your design is to use the Autorouter tool (the tool next to the ratsnest tool).

The yellow lines are not really the connections on your PCB it just indicates how your components are connected to each other. Using this tool will replace the yellow lines with solid and thicker wires, perfect to use for PCB etching.

A window will appear with lots of tabs and options bur I just hit OK and I went well. Your circuit will now look like this.

At this stage you should be finished. But I encountered problems here as some wires overlapped since I'm using a single-sided PCB (I think the red wire indicate one side of the PCB and blue wire are another side).

One solution the I found is to use the Route tool and the Ripup tool.

Route tool, as the name implies, manually routes the connections on your circuit - you can even use this instead of the Autoroute tool.

Ripup tool removes the 'routes' or the wires on the circuit and return back to the yellow lines, to be routed again.

Finally your circuit is finished! You can now print the circuit on a glossy paper. I recommend this type of glossy paper as it worked for me but I don't know what is the minimum gsm of the glossy paper or if that even matter.

I think I bought the right glossy paper when I saw this one at the back.

You're now ready to print! But don't print just yet! 
You don't want to print your board with the pictures of the components intact, only the wires (and holes) are needed to be printed.

The layers tool will remove the unnecessary layers in your circuit. just pick out the layers for the dimension of your board, wires, and holes.

NOW you're ready to print! In printing your circuit I printed over it twice for thicker ink and for easier ironing but the disadvantage of doing such is when I  removed the ink after etching (there was a lot of smudges and a lot of acetone were used) still it was just for aesthetic purposes and I realized that I will not be seen anyway.

Tune in as we continue our four part project series! Prepare your iron and PCB, and your ironing skills 'coz next time we'll transfer the toner!

For the ready to print circuit and the schematic diagram just hit download below (opens in a new window)