Sometimes, there's a question that almost answers one that you have. Perhaps the title is similar, or the other question specifically excludes a point that you're interested in.
For an example case, this old question, about PNP transistors, has an answer about their operation accepted without comment. It doesn't mention the physics behind the behavior, but Federico wants to know this information.
What should be done here? There are a few options:
- Ask your question, explaining the differences between yours and the [preferably linked] pre-existing question.
- Edit the previous question to include yours.
- Ask the poster of the previous question whether they'd like to include your topic, and take option 1 or 2 based on the result of this communication. Note that this may take some time (or never happen) if the OP doesn't visit regularly.
My opinion is currently quite firmly fixed on option 1, but I'd be interested to hear arguments from all sides.