IIT lecture notes

http://www.nptel.iitm.ac.in/

Electronics Tutorials

http://www.eleinmec.com/

http://www.kpsec.freeuk.com/

http://www.hobbyprojects.com

http://www.allaboutcircuits.com

http://www.williamson-labs.com/

http://www.electronics-tutorials.ws/

http://www.ecircuitcenter.com/

http://www.technologystudent.com/elec1/elecex.htm

www.play-hookey.com

Circuits & Circuit Analysis

http://www.aaroncake.net/CIRCUITS/index.asp

www.et.uncc.edu/elet_info/CircuitTutor/CircuitTutor.html

PCB Design

      www.alternatezone.com

Electronic Components

http://ourworld.cs.com/gknott5413/

http://science-ebooks.com/electronics/table_of_contents.htm

Operational Amplifiers

http://www.cs.manchester.ac.uk/Study_subweb/Ugrad/coursenotes/CS1231/tutorials/index.html

Microcontrollers and Microprocessors

http://mic.unn.ac.uk/miclearning/modules/micros/ch1/micro01notes.html

http://www.hobbyprojects.com

Semiconductors

http://ece-www.colorado.edu/~bart/book/title.htm

http://www.boin-gmbh.com/linkpage/indgui.htm

http://www.play-hookey.com/semiconductors/