Several developers maintain updated 74HCT collections on GitHub, such as Hennie Peters' LTSpice collection or the KiCad-Spice-Library. How to Install and Use the Library
Once you have downloaded the .lib (model) and .zip (symbols) files, you can integrate them using one of these two methods: Method 1: Project-Specific (Recommended for Portability)
The most comprehensive resource is the LTwiki-Wiki for LTspice , which hosts the massive collection of models curated by Alexander Bordodynov. You can find files like 74hct.lib directly in their library subdirectory . ltspice 74hct library download
Press F2 , change the "Top Directory" dropdown to your local folder, and select the desired 74HCT part.
On your schematic, press S to open the Spice Directive box and type: .inc 74hct.lib . Press F2 , change the "Top Directory" dropdown
Copy 74hct.lib and the corresponding .asy (symbol) files into the same folder as your .asc schematic.
To simulate logic gates in LTspice with realistic timing and voltage levels, you often need to go beyond the built-in [Digital] gates and download specific 74HCT libraries. This is especially true for the 74HCT series, which uses CMOS technology with TTL-compatible input thresholds. Where to Download 74HCT Libraries To simulate logic gates in LTspice with realistic
Because Analog Devices (the maker of LTspice) does not include a full 7400-series library by default, most users rely on community-maintained files.