Right now I am powering my circuit off of a 12V@1A wall-wort. The regulator is really hot to touch. The overall draw of the circuit is never over 350mA and typically around 225mA.

1. Why is it so hot to touch or why am I dissapating so much heat?

2. Why would someone use a 7805, when you could make a voltage divider? Is it because the voltage divider is not as constant voltage of different current draws as 7805?

The heat in the project box is a problem, because I am using this as a termostat and it is raising my temp sensor apx 3 degrees.

Thanks!