In this module the main commands and options for designing of a low complexity schematic will be learned. At the end of the module the student should be able to design a simple schematic and to make difference between the several components, items and objects.

·        Adding  parts

The command to bring symbols in the work area, PLACE PART, is an option that allows the user to call the part libraries and acces the desired part. Part libraries are oragnized in files with *.olb extension, from Orcad Library. They contain parts used in electronic schematics desgin. The libraries may contain the graphical description of the symbols of some physical parts ,for example transistors ,operational amplifiers, TTL digital circuits and also symbols for power sources or ground or pointing cartridges which might be attached in different pages of the designing schematics.

 

Pay attention with the notions used in CAD programs that might create confusions. By symbol, we strictly understand graphia representation of an electronic component.A part is visualized in the Schematic block by a symbol and may take different forms and informations diplay as the footprint associated to the PCB block,the number of units contained in  a footprint (i.e. de four gates AND-NOR contained by the  DIP16 footprint of the SN7400 intregrated circuit), other information related to the electric defining of the terminals (input,output,open collector),pin or gate swapping etc

 

ORCAD program understands by part the minimal logical unit placed in the drawing board used to design the schematic. If the desired schematic is to be simulated with SPICE then a part can represent a certain model or circuit function. If the schematic is inserted in Capture in ordere to realize the PCB usually the parts have correpsondent in real components. transistors, integrated circuits,connectors etc. These eletronic components are physically encountered with the form of footprints- package. A package is in fact a physical component (electronic  component or part)  which is planted on the PCB to realize the electronic mode functions.