The 7805 series voltage regulators require a 2V dropout. That means you have to have at least 7 volts input to give a constant 5V1A output. Wire up two 9V batteries, they drain faster, and heat up faster as well.

Perhaps using 7805SR/2575/1375 would be better. I heard it stays cool constantly. It's a switching regulator btw. Not too sure how much it costs though.


3:14PM
Aborted switching regulators.
You need a fast diode.
An inductor that does not saturate under high currents.
A low equivalent series resistance capacitor
.
I think it's overly complex for a damned charger.

3:24PM
I don't really need red jumper wire to differentiate polarity
I don't really need extra 9V clips
I don't really need USB sockets
I don't really need audio pin that urgently.
I only need batteries.

I can probably connect the battery in parallel to give it a lower difference and hence lower heat dissipated. (i don't quite recall my physics..)
Oh yeh, I have 2 voltage regulators to test though.