> i need to connect a pic to my car, using the 12v car battery...umm i
> assume i can't just wire up the car battery to like a 7805 to control the
> voltage..or maybe im wrong...Suggestions?

Linear regulators work fine for automotive use.  Just keep in mind that the
regulator will be dissipating more power than the circuit itself in this
configuration.  There will be 5V accross your circuit, but 7 to 9 volts accross
the regulator with the same current all the way through.  Also, if you want
your device to be really reliable in automotive use, you should design it so
that it can survive supply voltage up to about 20V (not normal, but it can
happen when the car's electrical system is malfunctioning), and down to
about 8V (cranking with very cold or low battery).  Automotive electrical
power is noisy, but it's not too hard to deal with unless your application has
some sensitive analog circuitry.  I typically use a 220uF electrolytic cap on
the input side of the regulator, and a 1000uF electrolytic in parallel with a
0.1uF ceramic on the output side.  Works great for powering PIC's.


---
                                        Peace,
                                        William Kitchen
                                        bill@iglobal.net

The future is ours to create.