Orcad is a suite of tools from Cadence for the design and layout of printed circuit boards (PCBs). We are currently using version 9.2 of the Orcad suite. This document will give you a crash course in designing an entire circuit board from start to finish. This will be a very small and simple circuit, but it will demonstrate the major concepts and introduce thetools behind completing a PCB design. After you have completed this tutorial, you will know all the steps needed to make PCBs using Orcad. The circuit you will design is shown in the figure below. It is a dual polarity adjustable power supply. A center tapped transformer, some diodes, 2 IC’s and few resistors and capacitors are included in the circuit.
Orcad really consists of two tools. Captureis used for design entry in schematic form. Layout is a tool for designing the physical layout of components and circuits on a PCB. During the design process, you will move back and forth between these two tools. WARNING : Save your work frequently while working on this tutorial. NOTE : It is recommended that you read this tutorial in 1024x768 display resolution.
2. Before You Begin
It ishelpful to be very organized when you are designing. First thing is to have a separate folder for every project. If you have a folder called Projects on your drive, don’t put all your projects directly in that folder or you will create a mess that will waste your time in locating a particular file of a particular project. Instead you must have a new subfolder in it for your every project. Also Orcadwill create many types of files for a single project and if you keep all of them in the same directory, it can quickly become very confusing. I like to make a directory hierarchy and put associated files into subdirectories. As you will progress working in Orcad you will realize the importance of this strategy. So ready for some action and create a folder called PowerSupply on a convenientlocation on your drive because you are going to browse it several times during this whole tutorial. Then create inside the PowerSupply folder three new folders.
schematic – for your schematic files. libraries – for symbol and footprint libraries. board – for your board files.
Your directory structure should look like the figure below.
3. Starting a New Schematic Project
To create a newproject, first start Orcad Capture CIS then click File New Project. You will see the following dialog box. Browse to the PowerSupply\schematic directory that you created and name the project psu (short for Power Supply Unit). The project name is more important than the name of your project folder. It is used as the name of all the files in your project. So give the project a meaningful and short name.Select the PC Board Wizard radio button and click OK. In the next dialog box uncheck Enable project simulation. Click Next and then remove all libraries from RHS then click Finish. You should see an empty schematic page and a project window like the following.
4. About Libraries and Parts
Orcad allows you to have libraries of part symbols for use in schematic entry. These libraries are kept inseparate files that are included in the project workspace. This allows you to reuse libraries in other designs. Enormous parts are already in existing Orcad libraries. You can use these parts directly from these libraries. Open your schematic page from the Project window if it is not open. Your schematic is located in psu.dsn SCHEMATIC1 PAGE1 in the project window. Now click on the Place Parttool from the right toolbar. The following dialog box appears.
This dialog box currently displays only the Design Cache. To use any of the part from Orcad built-in libraries, you need to add the library in which the part resides. Click on the Add Library button. Orcad Capture keeps all of its libraries in the path:
Browse to the said path and you will...
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