User Symbol and Footprint Libraries

I had trouble loading a LM338T symbol and footprint from two different well known sources.
I went ahead, following a kind member suggestion, using a different component from the same family, with identical pinouts and package.


I want to study this aspect and solve it “well done”

I have read many posts and how to’s about User Libraries, and I am now current with paths, tables, and so on.

I am missing:

A document to describe the internal structure of lib and kicad_mod files.
I found it for Version 2.3 but I was unable to find the Version 2.4 file struc document.

For instance, in LM338T files, either from SnapEda and, the F2 line points to TO254xxx instead of TO-220, as follows:

EESchema-LIBRARY Version 2.3
#encoding utf-8
#© SnapEDA 2016 (
#This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License (CC BY-SA) with Design Exception 1.0


DEF LM338T U 0 40 Y Y 1 L N
F0 “U” -500 239 50 H V L BNN
F1 “LM338T” -500 -357 50 H V L BNN
F2 “TO254P1054X470X1955-3” 0 0 50 H I L BNN

Thanks for any help or suggested articles.

Kind regards,

I’d suggest you use the standard KiCad libs first and only go to others as needed.

While the symbol lib MAY point to a footprint, that link is not necessary.

This document is the only description of KiCad file formats I know.

But why are you interested in it?

In older KiCad versions it was relatively common to edit files directly because of missing functionality in KiCad, but that was years ago. Sometimes it is still convenient to hack into those files, for example for bulk search & replace, but in KiCad V5.1.x you can do al regular library maintenance from within the GUI and with a few mouse clicks.

A short peek at the LM338T datasheet suggests that you can just use it as an alias of the LM317. Or (if I missed something) you can always simply make a copy of the LM338
7 schematic symbol as a starting point, modify it for the LM338 and save it in a custom library.

I do not have much experience with external libraries, because I find KiCad’s own libraries of better quality. The editors for Schematic Symbols and Footprint are also quite good in KiCad. So I do not even bother to go to sites like snapeda, but just make the parts myself if needed.

Schematic symbols are usually fairly simple Just a rectangle with some pins.

And regardless of whether you want to create your own parts, or get them from an external source, you should know how to manage libraries in KiCad.

If you do not already have a User Footprint Library for a TO-220-3 part, then you can NOT point the Symbol library part to that User Footprint. You can point your User Symbol to a Kicad KLC compliant Footprint (that might change in the future).

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.