DC to AC generator

[aadharmg]

If I make a generator which uses magnets as the rotor and the current-carrying coils as the stator, and the lights attached to it flicker when it's being fed mechanical energy, does this mean that I have a DC generator at hand? If so, what would I have to add/remove to make it an AC generator? I'm quite not clear on the whole commutator story in terms of AC generators - different places tell me different things on what I reckon shouldn't be such a complicated issue.