Hmm . I didn't use any zener, fuse, series resistors for my automotive applications. But still my PIC controlled Digital TACHO ( which is running for over 5 years now), 3rd break light, PIC Controlled LED UNDER CAR lightings are working fine without a problem. And I used 7805 with 100uf and 0.1uf cap for all of above mentioned projects.
Ya, blue is for snow removal vehicles here in my part of the world. We get all sorts of hassles about that here. Even headlights with too much blue tint.
I have to agree with Mark. Others have used non automotive regulators but I would not do so esp on a device I was selling. Murphy will get you. If there were no possibility of problem they would just use common regulators on cars.
The LM2931 are under $1 each. I have purchased them in 25 unit lots for maybe 35 cents. It is 100mA but I have found similar regulators in the TO-92 case up to 300mA. Next time you order pick up a few.
I've been taking apart automotive electronics for years and I've seen 7805's in quite a few automotive "modules". I'm going to look at some of the old spares I keep around and see what else they have in conjunction with the 7805 to see if they're taking special precautions.
Heh yeah its not legal here either.. .the most is a ticket. Its not my car tho. It was a job for a friend. Charged him $40. Hes like family. Now he has 3 customers lined up for it and im charging $150 each. Custom sequences too (4 included)... $20 each extra sequence.
It uses a CAR phone charger heh to supply power...
I would tell them not to drive around with those on, it would be seen by police as something like 'impersonating' the police car. People would probably start pulling off to side of road when they drive with those on!