I designed a circuit that consumes about 0.7 to 0.9 amperes depending on the state of its components.
I use a 7805 regulator to feed the circuit with 5V and the regulator is connected to a 12V adapter.
The regulator has to drop about 7 volts at 0.9 amperes maximum and it means about 6.3 watts of heat generated in the regulator. Changing the adapter is not an option because this circuit is a part of another circuit that needs 12V.
My question is: Is it possible to use a resistor to drop a couple of volts before the regulator? This may split wasted power between resistor and regulator. Am I right?