files for PWM controllers like the SG3524, SG3525, and TL494 on the All About Circuits forum SnapMagic (formerly SnapEDA) : Useful for obtaining the SG3524N Symbol and Footprint

When downloading and using libraries from third-party sources, ensure that:

Search for "Proteus-Library-Collection" to find community-maintained .LIB and .IDX files. Labcenter Electronics (Official):