I am preparing to publish a technical book on programming that contains figures and charts (like, compiler, linker, ASCII table, keywords list) created by myself by taking references from many sources. Can I still need copyright clearance for using them in my book as the diagrams and charts are not originally designed by mine? Is the common conceptual figures like flowcharts of compilers, and list of programming keywords or ASCII table comes under copyright?
You don't own the copyright from anything that you've taken as "references from many sources."
You'll need to check under what kind of copyright those sources are. You'll need copyright clearance and/or source attribution (eg, if those materials are under a Creative Commons licence).