Tower pro SG 5010 servo current

I have been powering a hobby servo from an Arduino but want to use an external source - a wall wart, 8v/500mA regulated with a 7806. This fails to run the servo. Nor does a 9v battery. I've read that these typically need as much as one amp each. The project needs three. Any ideas?

If the servo is under load, it may take 1a or more.