I am planning a LCD display application for my car using a PIC. I want it to be powered by the car's 12v system, and Im worried about electrical noise, surges, etc.
I was going to use a LM7805 voltage regulator and Capacitor to drop it to 5v. Is there anything else I should use to prevent noise or protect the circuit in other ways? Any added components have to be pretty small (TO-92 or similar size).
Im a bit of a newbie so specific part numbers would be helpful. Thanks.
There are lots of things you could add, including extra filtering, in-line chokes, over-volt zeners - but a 7805 will most probably be perfectly OK on it's own. As you are struggling for space, I would try it and see! - a car can be a very noisey electrical environment, with potentially large voltage spikes - it's a good idea to try and prevent these, even though they may not actually occur.
Yeah- use 2 capacitors, not 1. 0.33uF on input, 0.1uF on output. That's from the LM7805 spec sheet I just pulled from Digikey, if you do not use them the device may oscillate, this is very bad. Be sure you have a large voltage rating on the input cap, 30V is great. I believe larger caps is fine. Don't try to fix a problem that doesn't exist by putting in huge caps, though.