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09-23-2018, 03:12 PM
Hi guys
In Eagle and other PCB layout software, the components are stored in a parts "library". Eagle comes with some libraries developed over the years by its developers, and to which you can add your own parts. It is your choice whether to use the default libraries or to make your own for things that you use all the time, as this can save a lot of scrolling through the existing libraries.
Note that the libraries are listed alphabetically in the library directory. If you create your own directory it is convenient if it shows up at the top of the list. To force this, use numbers at least as the first part of the library name, or as the entire name. I use a couple of libraries named this way: one for laying out schematics, and another for laying out mechanical drawings for chassis and face plates.
Each component is called a DEVICE. A DEVICE is comprised of a SYMBOL that goes on the schematic and a PACKAGE that goes on the board. Each device can have s many packages as you wish, and some devices might actually require more than one symbol to be complete. For example, a resistor has only one functional element and thus has only one symbol, but because the resistor can be many different physical sizes, it can have many packages. A dual-triode, like a 12AX7, has three functional elements: two triodes and a heater. If the DUAL-TRIODE device is made correctly to assure proper schematic flow, the DEVICE will have three symbols and then one or more packages as required. Ideally, the 12AX7 should have two packages: one for mounting on the top side of the board and one for mounting on the bottom side. Alternatively, you can have one package and use the MIRROR tool once the package is placed on the board.
You can go in to the library directly, but it is usual to have a schematic open before invoking the Library directory.
In Eagle and other PCB layout software, the components are stored in a parts "library". Eagle comes with some libraries developed over the years by its developers, and to which you can add your own parts. It is your choice whether to use the default libraries or to make your own for things that you use all the time, as this can save a lot of scrolling through the existing libraries.
Note that the libraries are listed alphabetically in the library directory. If you create your own directory it is convenient if it shows up at the top of the list. To force this, use numbers at least as the first part of the library name, or as the entire name. I use a couple of libraries named this way: one for laying out schematics, and another for laying out mechanical drawings for chassis and face plates.
Each component is called a DEVICE. A DEVICE is comprised of a SYMBOL that goes on the schematic and a PACKAGE that goes on the board. Each device can have s many packages as you wish, and some devices might actually require more than one symbol to be complete. For example, a resistor has only one functional element and thus has only one symbol, but because the resistor can be many different physical sizes, it can have many packages. A dual-triode, like a 12AX7, has three functional elements: two triodes and a heater. If the DUAL-TRIODE device is made correctly to assure proper schematic flow, the DEVICE will have three symbols and then one or more packages as required. Ideally, the 12AX7 should have two packages: one for mounting on the top side of the board and one for mounting on the bottom side. Alternatively, you can have one package and use the MIRROR tool once the package is placed on the board.
You can go in to the library directly, but it is usual to have a schematic open before invoking the Library directory.
