source & sink input/output

pretty much how it sounds.

Sinking provides a path to supply common (-) npn

Sourcing provides a path to supply source (+) pnp

http://www.automationdirect.com/static/specs/sinksource.pdf

http://wiki.answers.com/Q/How_is_npn_transistor_different_from_pnp_transistor

With you question between the differences if your working with sensors, one would ans should know the differences. neither are interchangable.

I hope this helps.

I had an experience Electrical Engineer who did a project for me and screw this up. It custing I mean costed me dearly. As far as experienced EE, later found out he had a weakness for Jamison Whiskey

hello everyone, had an interview yesterday where the kind gentleman asked me what a sourcing and sinking input was. I got that sinking feeling when i couldn't answer the question. Looking for the answer just now i saw your signature and what you said about Jesus. this is not a co-incidence. I stubornly went to this interview by not listening to God, and here is the answer to the question i didn't have the answer to, and here also is the answer to that job. I should pay more attention to Jesus and less to my own desires.

God BLess