I can't find this particular Ic in the local market, is there anything which can replace it.

 

http://www.alibaba.com/showroom/voltage-comparator-ic.html

Scroll through these chips, several different IC voltage comparators are given. Perhaps one would work in your application.

 

Will any of these will work in this circuit http://www.coolcircuit.com/circuit/light_switch/index.html

 

Yeah the LM393 as well as the LM2903 should work fine. Also, if you look it up, most general purpose ICs can be used as comparators. I know that the LM324, AD817, and a couple of others have worked really well as comparators in a couple of projects that I have created.

 

Remember though that comparators typically have open collector (or open drain) outputs. Most amplifiers have some kind of push-pull output stage, so you probably cannot use them to drive a load returned to a voltage outside their own rails.