my obc-ncl category rank is 20000 and 75000 in general can I get dtu or nsit ..I am from outside delhi..

I hope the following links may help you :
1) JEE Main 2015 College Predictor
2) JEE Main Expected Marks or Rank to take admission in NIT Colleges 2015
3) List of colleges that accept JEE Main scores
4) JEE Main 2015 Participating Institutes

You can also find the closing ranks of various branches of different institutes (category-wise) from CENTRAL SEAT ALLOCATION BOARD( csab.nic.in ) website,for eg. http:// csab.nic.in /csab2014/PDF/Closing_Rank_After_Round_III.pdf

The chances are less if you are outside of Delhi to get admission in DTU & NSIT. But you can try there can be the possibilities for the same.