Solved ignition noise problem...thanks all!

[Sandy]

That is very similar to what I have, main power through a fuse, a TVS to
ground, 3 Amp diode feeding an inductors and related filter caps.  I think
the inductor does more then I think, but who knows, I have not tried it
without it. The diode in series is costly, but I think could be worth it.
The Low Drop out Regs are nice, and they are not that hard to get from
Digi-Key. The best thing is they are drop in, and high temp to boot.

Sandy

>For my own designs, I use a 1N4004 in series with the power then
>a 27V transient suppressor in parallel with a few hundred uF.
>This cuts out a lot of the nasties before my regulator which
>is a regular 7805.  A low dropout regulator would be better
>since I eat almost a volt with the diode.
>
>Orin.
>