CAD(Computer Aided Design) software is used to create a schematic and convert the schematic to a PCB.
Eagle Cadsoft software is available at:
There is a lite version that is free and what I am using. This version will limit you to PCBs 100x80mm(4x3.2 inches) and two layers(Top and Bottom). So far this is adequate for my purposes. I’m not going to go into a lot of detail as there are a lot of other tutorials that do a better job. I will add some tips that I used.
Here is a great Instructable for newbies:
Basic: Install and run Eagle Cadsoft, start a new project and draw schematic.
TIP: I installed it on a Windows 7 machine. It installed under:
C:\Program Files (x86)\EAGLE-6.2.0\
The first step is to create a schematic.
Components have two basic characteristics, electrical and physical: When adding parts or components, make sure you have the right package. The package is what it will look like on the PCB.
Integrated Circuits have two basic types. SMD is surface mount. But most hobbyists use through hole. These are the ones with the pins with long legs. See picture. These are sometimes referred to as DIP(Dual In Line Package).
Resistors and Capacitors: The above Instructable has some great tips on selecting these. Most can be found in the resistors library. Resistors can be installed vertically to save some space.
Finding library parts that match what you buy/have can be a challenge especially if you use ebay like I do. The stock library has a lot but it is often confusing and hard to find what you are looking for. I do a lot of internet searching to look for Eagle Cadsoft library parts.
Libraries I added:
The .lbr files are added to this directory on my PC:
C:\Program Files (x86)\EAGLE-6.2.0\lbr
TIP: I like to use all libraries to search for parts. To use all libraries, on the Eagle command line type use *. See picture for command line
TIP: Do not use Wire to connect components. Use NET. Net will automatically form junctions when terminated on pins or other nets.
Tip: Some ICs do not show power and ground connections. Put the part on the schematic, right click on it, select Invoke,select P (Pwr) and add connections. Then you can place it on the schematic
Tip: move a cluster of components. Use the group (select box) to select a rectangular group of parts, then select Move tool. CNTRL+RIGHT-CLICK, move the whole selection to where you want the group to go.
Advanced: You may have to create or modify your own library part. Here's a good Instructable:
http://www.instructables.com/id/How-to-make-a-custom-library-part-in-Eagle-CAD-too/It is really hard to do this. Avoid this if you can.