Down load the files to your PC and put in the LTspice lib folder.
\Documents\LTspiceXVII\lib\sub


2N7000.sub         Nmos

TP0606.sub          Pmos

1N4002.sub         Rectifier

NJM4556A.sub   Hi current OPamp
 
TL494.sub            PWM controler

TL494.asy            put in Documents\LTspiceXVII\lib\sym

LM311.sub           LM311 comparator

LM311.asy           LM311 put in Documents\LTspiceXVII\lib\sym