I should have been more specific - yes, you can "dim" AC fans and it's purely electrical. "Dimming" DC fans and similar switching loads requires detecting shaped pulses, and is really dirty and not something you want to do.
I should have been more specific - yes, you can "dim" AC fans and it's purely electrical. "Dimming" DC fans and similar switching loads requires detecting shaped pulses, and is really dirty and not something you want to do.