I need to power a small circuit that needs 7-12v 250mah.
I guess my choices are using 6 AA's in series, or a 9v.
If I use 6AAs, I'll get about 7.2 to 8.4 volts. I think that the best AA's are about 2500mah. Does that mean I should get *10 hrs* if my circuit needs 250mah???
If I used a single 9v, which is 180mah, I'll just get under an hour?
Question two is about battery life indicators.
I need a small easy circuit that shows some idea of how much power I have, or just that the battery is still good. Maybe just an LED that comes on as the batteries are getting low?
Any pointers to a simple circuit for this?