power supply

[Krister Wikstrom]

>Anyone out there have any solid simple cheap ideas for a 5V power supply for an

I'm making a simple ignition controller and would also like to get some
opinions on power supply for automotive application.

I have made a simple one like this (hope it is readable):

 
  --L---D-------[7805]----- +5V
      |   |  |         |  |
      C   Z  EC        C  Z
      |   |  |         |  |
      -   -  -         -  -

The first L and C should filter most high frequencies, the diode and the
large EC capasitor prevents sudden drops in voltage, and the first zener 
( I have 22V) should ease up voltage spikes. The last zener is just in case, 
and it actually sits in the CPU board along with some tantal. capacitors. 

Should this be enough?

  Krister Wikstrom
  kwi at mamma.icl.fi