Automotive Use

[Archangel]

Is this the "proper" way of sensing the state of a 12V source?

I have also seen voltage dividers or transistors used. Whats the best method for a 12V sense? (just detecting on (0V) or off (12V))

I decided to use the suggestion below, I would never use just 1 resistor, 2 would make a voltage divider, I wanted 5 volts across the useful voltage range an automotive system spans, and that's what the suggestion below provides, you do not have to go the expense of 1 amp regulators either, just the little TO-92 cased ones work fine.
JS

One thing I have seen used, but not used myself, is to use 78L05 regulators with the input to the high voltage you want to detect, and the 5v output going to the PIC input pin.
Seems pretty good in theory, as any variations in the input will just be absorbed by the regulator. A bit better than voltage divider etc???