Simple timing circuit

Hi, I'm working on a project that requires an adjustable timing circuit. The output of the circuit needs to be on/off voltage from either a set of watch batteries or AA batteries (I haven't decided yet). I need to be able to adjust the input voltage so I can get different time intervals between the output pulses. Any help on how to get started with this would be great. Thanks in advance.

Have you looked at 555 timers?

Details...details...details!

Output pulse width?
Time range between pulses?
What does the output drive?

Ken