Current from 2600/7800 controller port

[Viso]

I'm working on a new peripheral for the Atari 2600 & 7800 that connects to the controller port. I would like it to get its power from the controller port, which I have gotten it to do (at least for a short test), but I'm not sure how much current is too much. The device cannot be powered by the serial port of a PC, which I know can't manage much current, but I don't know how little it is. I'm doing some guess work without an ammeter. When I add together what the components claim to use, I get 3mA continous and 8mA peak.

 

I don't want to make the game systems' 7805 overheat. As it is, my 7800's gets pretty hot.

 

Thanks for the help!